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International Journal of Operational Research

International Journal of Operational Research (IJOR)

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International Journal of Operational Research (171 papers in press)

Regular Issues

  • Combinatorial Artificial Bee Colony algorithm hybridized with a new release of Iterated Local Search for Job-shop Scheduling Problem   Order a copy of this article
    by Amaria Ouis Khedim, Mehdi Souier, Zaki Sari 
    Abstract: Job shop Scheduling Problem (JSP) is recognized as an attractive subject in production management and combinatorial optimization. However, it is known as one of the most difficult scheduling problems. The present paper investigates the job shop scheduling problem in order to minimize the Makespan with a new hybrid combinatorial artificial bee colony algorithm. Firstly, the proposed combinatorial version integrates a Position Based Crossover for the updating of solutions and the Rank-Based Selection for selecting solutions to be updated in the onlooker bees phase. Another purpose of this study consists to highlight the impact of its sequential hybridization with a new release of iterated local search method called “Simple Iterated Local Search (SILS)”. The proposed approaches are tested on many benchmark problems taken from the Operations Research Library (OR-Library). The simulation results show that the hybrid CABC performs the best in most of the studied cases.
    Keywords: Job shop Scheduling Problem (JSP); Metaheuristics; Artificial bee colony Algorithm; Iterated Local Search.
    DOI: 10.1504/IJOR.2021.10028675
    by Sandeep Handa, Tilak Raj, Sandeep Grover 
    Abstract: In recent decades increase in environmental awareness has motivated the manufacturers towards minimizing the use of exhaustible resources. Green manufacturing focuses on manufacturing technologies and initiatives that optimize energy usage and resource conservation. Green manufacturing aims to minimize environmental impact of manufacturing activities. The central objective of green paradigm is the combination of economic and ecological efficiency. This study aims to identify the key enablers for green manufacturing. The study uses an integration of Decision Making Trial and Evaluation Laboratory (DEMATEL) and Analytic Network Process (ANP). The analysis reflects the interdependencies among the enablers of green manufacturing. The results indicates that Customer demand, Implementing eco innovation and Availability of collaborative suppliers are the top three enablers for the transition towards green manufacturing.
    Keywords: Green Manufacturing; Enablers; DEMATEL; ANP.
    DOI: 10.1504/IJOR.2021.10028924
  • Application of a Mobile Facility Routing Problem in a delivery company   Order a copy of this article
    by Sonia Avilés-Sacoto, Osmar Salvador-Grijalva, Galo Mosquera-Recalde 
    Abstract: Nowadays e-commerce business has created new distribution channels to reach customers. This setting includes policies and changes in the delivery process, such as small orders, short delivery schedules, and variables workloads. One approach to meet these requirements is mobiles facilities, which place products closer to customers with known location and product requirements. However, finding out the right position for the mobile facilities considering time and demand variability constitutes a challenge. This study proposes a methodology to determine the location and time where mobile facilities should be to optimize the delivery of products. Several tools such as clustering, routing problem optimization, and Monte Carlo simulation are combined with the aim to minimize the transportation costs associated to the delivery of the products and the cost associated to the unmet demand. A real case study is presented with the optimal route for two mobile facilities for a 15-minutes time window.
    Keywords: Mobile Facility; Routing Problem; Monte Carlo Simulation; Clustering; Delivery; Transportation; Costs; Vehicles; Demand; Strategic Points; Time window.
    DOI: 10.1504/IJOR.2021.10029093
  • An EOQ model for non-instantaneous deteriorating items with time-dependent quadratic demand and two-level pricing strategies under trade credit policy.   Order a copy of this article
    by Babangida Bature, Yakubu Mamman Baraya 
    Abstract: In this paper, an EOQ model for non-instantaneous deteriorating items with two phase demand rates and two-level pricing strategies under trade credit policy is considered. It is assumed that the unit selling price before deterioration sets in is greater than that after deterioration sets in. Also, the demand rate before deterioration sets in is assumed to be continuous time-dependent quadratic and that after deterioration sets in is considered as constant and shortages are not allowed. The main purpose of this research work is to determine the optimal cycle length and corresponding economic order quantity such that the total profit of the inventory system is optimise. The necessary and sufficient conditions for the existence and uniqueness of the optimal solutions are established. Numerical examples are given to illustrate the theoretical result of the model, Sensitivity analyses of some model parameters on the decision variables were carried.
    Keywords: economic order quantity; non-instantaneous deteriorating items; time-dependent quadratic demand rate; two-level pricing strategies; trade credit policy.
    DOI: 10.1504/IJOR.2020.10030065
  • Hierarchical learning model for early prediction of coronary artery atherosclerosis   Order a copy of this article
    by Muruganantham Sowmiya, B. Banu Rekha, Elangeeran Malar, K.R. Ashwin Kumaran 
    Abstract: Drastic improvement in the field of science and technology have made the lives of humans more sophisticated. As a result, physical activities in which the people indulged have reduced and this has made them prone to Coronary Artery Disease (CAD). Coronary Artery Atherosclerosis (CAA) is one of the main causes of CAD and therefore, early prediction of CAA is indispensable to prevent the risk of people getting affected by CAD and sudden deaths. This work presents the machine learning model which provides more information on the exceptional cases while retaining the existing traditional classifier model. The proposed model performs outliner detection using Local Outlier Factor (LOF) and class balancing using Synthetic Minority Oversampling Technique (SMOTE). Genetic algorithm is used for prominent feature selection and utilizes Support Vector Machine (SVM) and Neural Network (NN) as classifier. UCI and South African Heart disease datasets are used to implement the proposed model.
    Keywords: Machine learning; support vector machine; neural network; local outlier factor; feature selection.
    DOI: 10.1504/IJOR.2020.10033098
  • Fuzzy multi-objective programming for supplier portfolio formation: A credibility based approach   Order a copy of this article
    by Garima Mittal 
    Abstract: In a multiple-sourcing environment, supplier selection plays an integral role in efficiently managing a supply chain of an organization. This paper proposes a fuzzy multi-objective programming model using a credibility measure, for forming a portfolio of suppliers. Credibility measure has an advantage of self-duality over more prevalent possibility measure. In this paper credibility measure of a fuzzy event is used to model the three objectives of minimizing expected cost, maximizing expected quality and maximizing the expected on-time delivery, along with other realistic constraints that are integral part of the supplier selection problems. The proposed credibilistic model is solved using a fuzzy goal programming approach that has then been extended to three different scenarios in order to address decision maker's satisfaction with respect to the achievement level of the various objectives. A numerical illustration is also provided to depict the utility of the proposed model and approach.
    Keywords: Fuzzy supplier portfolio; Expected value model; Fuzzy multi-criteria decision making; Credibility measure; Fuzzy goal programming; Supplier selection.
    DOI: 10.1504/IJOR.2021.10030523
  • A Multiple Criteria Decision Making improvement strategy in complex manufacturing processes   Order a copy of this article
    by Soltani Mohyiddine, AOUAG Hichem, Mouss Mohamed Djamel 
    Abstract: The purpose of this paper is to propose an improvement strategy based on multi-criteria decision making approaches, including fuzzy analytic hierarchy process (AHP), preference ranking organisation method for enrichment evaluation II (PROMETHEE) and viekriterijumsko kompromisno rangiranje (VIKOR) for the objective of simplifying and organising the improvement process in complex manufacturing processes. Firstly, the proposed strategy started with decision makers selection including leaders company to determine performance indicators. Than fuzzy AHP is used to quantify the weight of each defined indicators, finally, the weights carried out from fuzzy AHP approach are used as input in VIKOR and PROMETHE II to rank the operations according to their improvement priority. The results obtained from each outranking method are compared and the best method is determined.
    Keywords: analytic hierarchy process (AHP); VIĀšekriterijumsko KOmpromisno Rangiranje (VIKOR); Fuzzy Logic; PROMETHE; improvement priority; Complex manufacturing process.
    DOI: 10.1504/IJOR.2021.10030582
  • Multi-Criteria Optimization of Fire Station Location in Gaza Strip   Order a copy of this article
    by Abdelrahman Abuserriya, Sadiq Abdelall, Salah Agha 
    Abstract: Fire stations along with their locations in Gaza Strip are extremely important because of the political situation This paper evaluated fire stations locations and suggested how to improve their performance in Gaza Strip The paper uses two models, these models include set covering and goal programing models, the models were solved in two stages: the first stage used the set covering model to determine the number of fire stations needed for given time limits (6, 8 minutes) The output of the first model was inputted into second model to determine the locations of fire stations Further, several scenarios were proposed for sensitivity analysis The first scenario freely identified the locations of each fire station, while the second scenario was forced model to select/unselect given locations based on decision makers preferences Based on fire department request which called for expansion through identifying the optimum number and locations of new fire stations.
    Keywords: fire stations location; goal programing; Gaza Strip; multi criteria; set covering.
    DOI: 10.1504/IJOR.2020.10030604
  • Optimal Production Output and Frequency of Rest-Breaks for a Worker Subjected to Fatigue   Order a copy of this article
    by Mohammed Darwish, Khaled Alali, Adel Alshayji 
    Abstract: It is reported by many researchers that the quality of produced items deteriorates and work-related incidents increase when a worker is subjected to high level of fatigue at workplace. As a direct consequence, the daily production yield of the worker decreases which, in turn, reduces the profit of a company. Some authors suggested short breaks at workplace so that the worker overcomes fatigue and improve productivity. In this paper, we mathematically study this relationship and develop a model that finds the optimal work-rest schedule such that the daily production output of a worker is maximized. We assume that the worker fatigue increases exponentially during work. Unlike the models used in the literature, the reduction in the worker fatigue level is modeled by utilizing concepts in the preventive maintenance engineering literature. This simplifies the solution method significantly.
    Keywords: Operations research; production; worker safety; rest-breaks; worker fatigue; exponential fatigue function.
    DOI: 10.1504/IJOR.2020.10030660
    by SONIA GOEL, Deepak Gupta 
    Abstract: This paper is an attempt to schedule n-jobs on two machines with parallel equipotential machines at every stage. The operating costs of all jobs on all parallel equipotential machines are given. The dispensation time of all the jobs on all the two machines is given and the time for which parallel equipotential machines are available is also known. The purpose of this work is to find the best possible schedule of jobs with the intention to diminish the entire elapsed time. The algorithm developed is illustrated with the help of example.
    Keywords: Scheduling; Elapsed time; equipotential machines; operating cost.
    DOI: 10.1504/IJOR.2020.10030702
  • Optimizing Fully Fuzzy Interval Integer Transshipment Problems   Order a copy of this article
    by A. Akilbasha, Pandian Ponnaiah, Natarajan G 
    Abstract: In this paper, we focus on solving fully fuzzy interval integer transshipment (FIIT) problems where the unit shipping costs, available supply capacities, and required destination demands are triangular fuzzy interval integers. An innovative method namely, back order sequence method has been developed for finding an optimal solution of the fully FIIT problem. The proposed method provides that the optimal values of decision variables and objective function value for the fully FIIT problem are fuzzy interval integers. A numerical example is presented to illustrate the solution procedure of optimizing fully FIIT problems. The optimal solution to the transshipment problem by the proposed method can help the managers to take an appropriate decision regarding transshipments.
    Keywords: Interval; Fuzzy set; Fuzzy interval; Transshipment problem; Optimal solution; Back order sequence method.
    DOI: 10.1504/IJOR.2020.10030761
  • In-House Production vs Outsourcing: the Effect of Volume-Based Learning on Quality Competition   Order a copy of this article
    by Yanni Ping, Seung-Lae Kim 
    Abstract: This paper considers an original equipment manufacturer (OEM) who outsources finished products to a contract manufacturer (CM), who adopts the OEMs existing technology and achieves quality improvement through learning-by-doing. Besides the role of upstream partner, the CM also becomes a downstream competitor. We examine learning-by-doing and quality dynamically under a two-period model both for cases when quality competition exists and does not exist. We identify the conditions under which pure outsourcing, partial outsourcing, or non-outsourcing is most advantageous. When there is no quality competition and when the CMs quality improvement does not hurt the OEMs future demand, we find that it would still be beneficial for the OEM to apply a partial outsourcing strategy. When quality competition exists, the OEMs decision in the second period follows the same pattern as the non-competition case, while the CMs wholesale price depends on the trade-off between selling through the OEM and selling independently.
    Keywords: learning-by-doing; outsourcing; quality-improvement; competitive CM.
    DOI: 10.1504/IJOR.2020.10030816
  • Research on Optimal Product Supply Strategies for Manufacturer-to-Group Customer under a Real Demand Pattern   Order a copy of this article
    by Zhiyi Zhuo 
    Abstract: In a product supply chain, customer demand determines the market and supply as well as the benefits accruing to manufacturers and retailers. Customer demand has three different patterns: real, false, and semi-real. This paper develops a mathematical model to investigate the factors that determine manufacturers design and plan of product supply strategies for group customers under the real demand pattern and solve for maximum profit. We use numerical examples to verify the validity of the model. This papers contribution is the construction of two mathematical models for off-invoice mode and unsold recycling mode of manufacturer-to-group customer product supply strategies under a real demand pattern.
    Keywords: Real demand pattern; Product supply strategies; Profit function; Optimal method.
    DOI: 10.1504/IJOR.2020.10030854
  • A Complete Information PCA-Imprecise DEA Approach for Constructing Composite Indicator with Interval Data: an Application for Finding Development Degree of Cities   Order a copy of this article
    by Hashem Omrani, Kolsoom Zamani 
    Abstract: Composite indicator approach is widely used for finding development degree of regions.This paper presents a complete information principal component analysis (CIPCA)-Imprecise data envelopment analysis (IDEA) approach for finding development degree of cities with uncertain data. CIPCA is applied to reduce the number of indicators. The output of the CIPCA is a set of new indicators with lower and upper bounds. These indicators are considered as indicators of IDEA and final ranks of cities are calculated by IDEA model. To illustrate the capability of CIPCA-IDEA approach, the development degrees of cities in Kurdistan province of Iran are calculated. First, 62 development indicators are selected and the related interval data for year 2015 are gathered. Then, the proposed approach is applied for nine cities of Kurdistan province and development degree for each city is finally calculated. The results indicate that in the overall ranking, Bijar city is top ranked.
    Keywords: Composite indicator; CIPCA; IDEA; Development degree.
    DOI: 10.1504/IJOR.2020.10030855
  • Development of a Heuristic for No-Wait Flowshop Production Process to Minimize Makespan   Order a copy of this article
    by Azahar Alam 
    Abstract: No-wait flow shop production system has much practical application in manufacturing industries. Minimisation total completion time of no-wait flow shop comes under the NP-complete category. Consequently, getting effective and efficient quality of result for such types of problems is a challenge where effective means optimal or near-optimal solution and efficient means which taking less computational time. A heuristic is proposed for the problem under consideration, in which problem is getting solved in two phases. The first phase is the initial sequence generation, and the second one is the improvement phase. Proposed heuristic is compared with four best-known heuristics, and for smaller size problem exhaustive enumeration is used to check the performance of the heuristic. Moreover, heuristic performance is tested over 600 randomly generated problem of different sizes. For large size problem, it showed that proposed heuristic is very much efficient.
    Keywords: Heuristic; No-wait flowshop problem; Makespan minimisation; Computational complexity.
    DOI: 10.1504/IJOR.2020.10030900
  • JACKKNIFING THEN MODEL AVERAGING: Investigating the Improvements to Fitness to Data and Prediction Accuracy of Two-Input Under- and Just-Fitted Response Models   Order a copy of this article
    by Domingo Pavolo, Delson Chikobvu 
    Abstract: The possibility of improving the fitness to data and prediction accuracy of models in a multi-response surface methodology environment of under and just-fitted ordinary least squares response models by jackknifing then combining the resultant partial estimates and the pseudo-values using arithmetic averaging or criterion-based frequentist model averaging was investigated. Jackknifing is known to reduce parametric and model bias. Model averaging is known to reduce model bidirectional bias and variance. A typical multi-response surface methodology dataset and resultant validation dataset were used as example. Results suggest that it is possible to obtain better fitness to data and prediction accuracy by jackknifing a just-fitted response model of interest and combining the resultant partial estimates using arithmetic averaging. The combining of pseudo-values using arithmetic averaging or criterion-based frequentist model averaging gave mixed results. The actual jackknife model estimators gave good performance with under-fitted models.
    Keywords: KEY TERMS: multiresponse surface methodology; jackknifing; partial estimates; pseudo-values; arithmetic model averaging; criterion-based frequentist model averaging.
    DOI: 10.1504/IJOR.2020.10030928
  • Detection of the Diffusion Nanoparticle in the Turbulent Flows Using the Random Walk Model   Order a copy of this article
    by Mohamed El-hadidy 
    Abstract: A probabilistic detection model is proposed to determine the location of random walk nanoparticles in the turbulent flows. This model maximises the benefits for the environmental, industrial and biological applications. In this paper, we present a generalised coordinated linear detection technique to find a one-dimensional random walk nanoparticle between two layers in turbulent flows. We have two sensors start the searching process from any point rather than the origin. The initial position of the nanoparticle is a random variable that has a known probability distribution. More than showing the existence of a finite search plan, we derive some auxiliary results related to optimal search plan which minimises the expected value of the first meeting time between one of the sensors and the nanoparticle. A numerical example is provided to illustrate the effectiveness of this technique.
    Keywords: Turbulent flows; Random Walk nanoparticle; Probability space.
    DOI: 10.1504/IJOR.2020.10030931
  • Solving the Team Orienteering Problem with Time Windows and Mandatory Visits Using a Constraint Programming Approach   Order a copy of this article
    by Ridvan Gedik, Emre Kirac, Furkan Oztanriseven 
    Abstract: This paper presents a constraint programming (CP) approach for solving the team orienteering problem with time windows and mandatory visits (TOPTW-MV), which has many real-world implementations, such as tourist tour planning, routing technicians, and disaster relief routing. In the TOPTW-MV, a set of locations is given; some locations must be visited, while others are optional. For each location, the profit, service time, and service time window information are known. A fleet of homogeneous vehicles is available for visiting locations and collecting the profits. The objective in solving this problem is to create a set of vehicle routes that begin and end at a depot, visit mandatory locations exactly once and optional locations at most once, while observing other restrictions such as time windows and sequence-based travel times. The CP-based approach finds 99 of the best-known solutions and explores 64 new best-known solutions for the benchmark instances.
    Keywords: Team orienteering problem; time windows; mandatory visits; vehicle routing; constraint programming; CP; optimization.
    DOI: 10.1504/IJOR.2020.10030954
  • Distribution and inventory planning in multi-echelon supply chains under demand uncertainty   Order a copy of this article
    by Joaquim Jorge Vicente, Susana Relvas, Ana Barbosa-Póvoa 
    Abstract: Distribution and inventory planning in a multi-echelon system are studied under an uncertain demand context. To deal with this problem a mixed integer linear programming (MILP) model is proposed. This considers a multi-echelon system formed by N-warehouses and M-retailers. The problem consists on determining the optimal reordering plan for the operating network, which minimises the overall systems operation cost. The uncertain demand faced by retailers is addressed by defining the optimal safety stock that guarantees a given service level at each regional warehouse and each retailer. Also, the risk pooling effect is taken into account when determining inventory levels in each entity. A case study based on a real retailer distribution chain is presented and solved.
    Keywords: supply chain management; inventory planning; mixed integer linear programming; MILP; guaranteed service approach; demand uncertainty; risk pooling.
    DOI: 10.1504/IJOR.2021.10031096
  • The problem of detecting nonlinearity in time series generated by a state-dependent autoregressive model. A simulation study   Order a copy of this article
    by Fabio Gobbi 
    Abstract: The aim of the paper is to try to measure, through a Monte Carlo experiment, nonlinearity in time series generated by a strictly stationary and uniformly ergodic state-dependent autoregressive process. The model under study is intrinsically nonlinear but the choice of parameters strongly impacts on the type of serial dependence making its identification complicated. For this reason, the paper exploits two statistical tests of independence and linearity in order to select the parameter values which ensure the joint rejection of both hypothesis. After that, our study uses two measures of nonlinear dependence in time series recently introduced in the literature, the auto-distance correlation function and the autodependence function, in order to identify nonlinearity induced by the proposed model.
    Keywords: nonlinear time series; independence test; linearity test; auto-distance correlation; autodependogram.
    DOI: 10.1504/IJOR.2020.10031177
  • Real Coded Self-Organizing Migrating Genetic Algorithm for nonlinear constrained optimization problems   Order a copy of this article
    by Avijit Duary, Nirmal Kumar, Md. Akhtar, Ali Akbar Shaikh, Asoke Kumar Bhunia 
    Abstract: The objective of this article is to propose a new hybrid algorithm named as real coded self-organising migrating genetic algorithm (C-RCSOMGA) by combining real coded genetic algorithm (RCGA) and modified self-organising migrating algorithm (SOMA) for solving the nonlinear constrained optimisation problems. In RCGA, a modified mutation operator called as double mutation operator has been introduced combining two different existing mutation operators, whereas in SOMA, a modified strategy has been proposed. To test the performance of the proposed algorithm, a set of test problems taken from the existing literature has been solved and the simulated results have been compared numerically as well as graphically with the existing algorithms. In the graphical comparison, a modification of performance index (PI) has been made. Finally, with the help of modified performance index (MPI), it has been shown that the proposed hybrid algorithm has performed much better than the existing algorithms.
    Keywords: genetic algorithm; self-organising migrating algorithm; SOMA; performance index; nonlinear constrained optimisation; global optimisation.
    DOI: 10.1504/IJOR.2020.10031300
  • Aggregate Production Planning of Abu Ghraib Dairy Factories based on Forecasting and Goal Programming   Order a copy of this article
    by Wakas Khalaf, Mustafa G. Ali 
    Abstract: The aim of this article is to build a comprehensive multi-objective production plan for Al-Rafidain plant spanning 12 months based on two methods the auto regression integrated moving averages (ARIMA) model to forecast the market demand for the products and the method of goal programming (GP) to find compatible solutions among the goals to be achieved. The ready-made program MATLAB was used to find the future values of the time series and also to solve the multi-objective mathematical model. For the most important results achieved, the mathematical model was able to achieve the first goal by 97%, which was the maximisation of profits; the total profits achieved a value of USD3,625,856. The second goal was achieved successfully because of the decrease that occurred in the costs, the value of which was USD2,456,625. Finally, the third goal was achieved by 98%, in that the plants return on investment was decreased to 1.476.
    Keywords: aggregate production planning; APP; goal programming; forecasting; auto regression integrated moving averages; ARIMA.
    DOI: 10.1504/IJOR.2020.10031453
  • Multi-objective optimization for solving cooperative continuous static games using Karush   Order a copy of this article
    by PAVAN KUMAR, Hamiden Abd El- Wahed Khalifa 
    Abstract: This paper introduces cooperative continuous static games (CCSG) with parameters in the cost functions of the players and in the right-hand side of the constraints. The CCSG is converted into the corresponding multi-objective nonlinear programming problem. The resulted nonlinear programming problem is converted into the single objective nonlinear programming problem through the use of the weighted sum method. A solution method for obtaining the stability set of the second kind without differentiability for the CCSG is presented using Karush-Kuhn-Tucker conditions. A numerical example is given for the illustration.
    Keywords: Cooperative continuous static games; Efficient solution; Weighted sum method; optimal solution; Karush-Kuhn-Tucker conditions; Stability.
    DOI: 10.1504/IJOR.2020.10031969
  • Misspecification of Data Envelopment Analysis   Order a copy of this article
    Abstract: Data envelopment analysis (DEA), a non-parametric efficiency estimator uses linear programming technique for the computation of estimates of decision-making units, such as, universities, schools, hospitals, banks, or mutual funds. There has been an ongoing debate about the application of the DEA model for model misspecification and in particular the inefficiency error of production for input and output variables. This paper contributes to this debate by examining several misspecifications of the DEA model in Monte Carlo (MC) simulations. MC simulations are conducted to examine the performance of the DEA model under two different data generating processes, stochastic and deterministic, and across five different misspecification scenarios, inefficiency distributions (traditional and proposed approaches), sample sizes, production functions, input distributions, and curse of dimensionality.
    Keywords: data envelopment analysis; DEA; inefficiency distributions; Monte Carlo simulations.
    DOI: 10.1504/IJOR.2021.10032036
  • Markov manpower planning models: a review   Order a copy of this article
    by Virtue Ekhosuehi, Vincent A. Amenaghawon, Augustine Osagiede 
    Abstract: A manpower system is a network of individuals working together in an organisation for the purpose of achieving the common goal of the organisation. To ensure that the right number of individuals is available to meet the task to be performed by the organisation, manpower planning techniques are needed. This paper reviews the manpower planning literature with specific interest on manpower systems modelled within the Markov chain context. Markov chains provide a convenient framework to: analyse the structural mechanisms, which underlie social change, and extrapolate shifts in the state distribution of the system; control personnel structures by framing optimal promotion and recruitment strategies; evaluate personnel policies; and deal with heterogeneity and uncertainty in the system configuration. This paper surveys these applications areas and highlights the methodological issues arising from varying the unit interval of the Markov manpower system in discrete time.
    Keywords: embeddability problem; heterogeneity; manpower planning; manpower system; Markov chain; personnel structure; stochastic matrix; sub-stochastic matrix; transition matrix.
    DOI: 10.1504/IJOR.2020.10032112
  • Agent-based modelling in Capacitated Lot Sizing Problem with Sequence dependent Setup time   Order a copy of this article
    by P. Raghuram 
    Abstract: Setups are indispensable in production, but consume substantial amount of productive time It is vital to consider sequence dependent setup times for determining production lots to satisfy demand for diversified product types on parallel production lines Optimisation is the most used technique to generate detailed schedules for such sequencing problems But the feasibility of the solution is not guaranteed under uncertainty conditions Thus, evaluating the solution configurations under uncertainty is necessary to confirm feasibility In this paper, an agent-based, discrete event simulation technique is used to develop a flowshop model which faces demand for multiple product varieties, and has sequence dependent setup time The simulation aims at evaluating various results in the solution space of an optimisation model to check their feasibility under various uncertain conditions in the form of setup time, processing time, and demand Results indicate that uncertainty influences overtime cost, holding cost, and lost sales.
    Keywords: Agent-based modelling; capacitated lot sizing model; flow shop scheduling; optimization; simulation.
    DOI: 10.1504/IJOR.2020.10032542
    by Lav Ishan 
    Abstract: The Indian insurance industry is moving towards integrating the latest technology in their business activities, as this can help in increasing the company’s efficiency. The use of mobile is high among the current generation, using this platform by insurance companies as a part of their business activities can help the company in many ways. This paper focuses on the use of mobile software by the customer and what are the factors which drive its use. Quantitative data were collected using questionnaire and interview of the respondent was taken to get an in-depth perspective regarding the mobile application. It was found out that the mobile application of insurance companies is used less by the customers and the way of increasing the use of the application is discussed. Findings can help the companies in determining how they can popularise their company’s mobile application among their existing and targeted customers.
    Keywords: Indian Insurance Industry; Insuretech; Multi-Criteria Decision Making; Analytical Hierarchal Process.
    DOI: 10.1504/IJOR.2020.10032564
  • Multi-resource balancing: A case of a German kitchen manufacturer   Order a copy of this article
    by Sina Glaeser, Christian Ullrich 
    Abstract: We address a multi-resource balancing-problem at Nobilia-Werke J. Stickling GmbH & Co. KG, the leading kitchen manufacturer in Germany. Nobilia maintains no warehouse for finished goods. The customised cabinets of a kitchen are manufactured in parallel and aggregated just in sequence for loading into trucks immediately after production. A smooth flow of materials is essential to ensure on-time completion and loading of a whole kitchen. Nowadays, changing customer tastes drive customisation. Due to an increasing number of capacity restrictions in its production processes, Nobilias current planning method has reached its limits. We present an integer programming model to address a variant of the multi-resource generalised assignment problem (MRGAP). We consider a multi-criteria objective function and a set of constraints reflecting Nobilias requirements. We propose a software-based solution approach for Nobilias instance sizes. The results of our computational experiments on real-world data demonstrate that our approach provides significant benefits.
    Keywords: resource balancing; integer programming; multi-criteria; production planning; machine assignment; mass customisation; generalised assignment problem; GAP; real-world application; LINGO.
    DOI: 10.1504/IJOR.2021.10032585
  • Numerical Optimization of Loss System with Retrial Phenomenon in Cellular Networks   Order a copy of this article
    by Vidyottama Jain, Raina Raj, Dharmaraja Selvamuthu 
    Abstract: In this study, we extend upon the model by Haring et al. [IEEE Trans. Veh. Technol. 50, 664-673 (2001)] by introducing retrial phenomenon in multi- server queueing system. When at most g number of guard channels are available, it allows new calls to join the retrial group. This retrial group is called orbit and can hold a maximum of m retrial calls. The impact of retrial over certain performance measures is numerically investigated. The focus of this work is to construct optimization problems to determine the optimal number of channels, the optimal number of guard channels and the optimal orbit size. Further, it has been emphasized that the proposed model with retrial phenomenon reduces the blocking probability of new calls in the system.
    Keywords: Multi-server queueing model; retrial phenomenon; cellular network; blocking probability; optimization.
    DOI: 10.1504/IJOR.2020.10032709
  • Efficiency Analysis of Selected Bank-Sponsored Mutual Fund Schemes in India   Order a copy of this article
    by RAJIB DEB, Soma Panja 
    Abstract: There has been growing literature related to performance analysis of the mutual fund (MF) industry concentrating on the non-parametric approach. Because of the practical and academic importance of mutual funds, it is becoming a vital area of research in finance. The present study seeks to gauge the efficiency of 40 equity mutual fund schemes that belong to seven asset management companies categorised as bank-sponsored under AMFI in India. The study uses data envelopment analysis technique as the prime tool for knowing the efficiency of selected schemes. The study discovers only seven schemes as efficient out of total sampled schemes and in which Canara Robeco Asset Management Co. Ltd offers the maximum number of efficient schemes as compared to others. The present study will offer direction for future research and will also provide individual investors with a guideline for selecting funds.
    Keywords: bank-sponsored mutual funds; data envelopment analysis; performance efficiency.
    DOI: 10.1504/IJOR.2021.10032840
  • Simulation-Based Optimization Approach to Multi-Choice Transportation Problem   Order a copy of this article
    by N.Tuba Y?lmaz Soydan, Ahmet Mete Çilingirtürk 
    Abstract: The classical transportation problem assumes that freight costs from source to destination are constant and that the supply and demand quantities are equal and strictly known, so the market for the product is well-balanced It thus involves a special type of linear integer programming, which becomes stochastic since the constraints or parameters are random variables from a known or unknown distribution Several studies have formulated well-known deterministic models under probabilistic restrictions The transformed models mostly keep the confidence level at a given minimum constant or else minimize the error level Also, there is a multi-choice stochastic transportation problem, which introduces several unit costs In this study, we try to simulate Roy’s (2014) multi-choice stochastic transport model with random supply and demand quantities from a given Weibull distribution and compare the results of distribution and total costs.
    Keywords: Simulation-Based Optimization; Multi-Choice Transportation Problem; Weibull Distribution.
    DOI: 10.1504/IJOR.2020.10033235
  • A Bibliometric and content analysis of core researches on Operations Research   Order a copy of this article
    by Nikunja Mohan Modak, Alok Raj, Shib Sana 
    Abstract: Operations research emerged as a discipline after the Second World War due to its efficiency to make better decisions. The socio-economic environment world over has changed over the last 50 years, and operations research has played a vital role in complex decision-making. Advanced analytical methods of operations research are effective for improving decision-making and solving real life problems in business, industry, and society. This work presents a bibliometric and content analysis of core publications of operations research. This study exclusively considers publications with operations research in their title. We have used SCOPUS, a reliable database, to collect relevant data. It presents overall publications and structure of citations. It comprehensively studies the significant contributions of journals, universities, and countries on this topic. Using the visualisation of similarities viewer software, it presents network visualisations and analyses co-occurrence of keywords, co-citations, and bibliographic coupling of institutions and countries. Finally, the paper reviews highly influential articles in this field and provides comprehensive direction for future research in this field.
    Keywords: operations research; Scopus; bibliometrics; VOS viewer.
    DOI: 10.1504/IJOR.2020.10033633
  • Cash discount associated permissible delay sensitive Economic Order Quantity (EOQ) systems in favor of deteriorating commodity of Weibull distribution receptive demand and Shortages   Order a copy of this article
    by Rakesh Tripathi, Hari Shyam Pandey 
    Abstract: Inflation is a major problem in the entire world. Inflation and time value of currency both are analogous to each other. In this learning demand is measured two Weibull parameters. Shortages and deterioration both are taken into account. Main goal of this work is to find the most favorable replenishment planning so that total cost in minimized. Mathematical models are consequential under the four dissimilar circumstances. Optimal solution is obtained by solution procedure. Numerical designs are offered to confirm the model expected in study. Sensitivity analysis is specified for distinction of dissimilar parameters. Mathematics 7.0 is used for finding numerical outcomes.
    Keywords: Cash- discount; trade credits; Weibull distribution; deterioration; cycle time; Demand.
    DOI: 10.1504/IJOR.2021.10033798
  • A Comparison of Different Mathematical Models for the Job Sequencing and Tool Switching Problem with non-identical Parallel Machines   Order a copy of this article
    by Dorothea Calmels 
    Abstract: This paper addresses the generalisation of the NP-hard job sequencing and tool switching problem with non-identical parallel machines and sequence-dependent setup times where a set of jobs is to be scheduled on unrelated parallel machines with machine-dependent processing and tool switching times. Three different mathematical models for two different objectives are presented and applied to newly generated test instances. The instances are compared and analysed using a commercial solver and an iterated local search heuristic. Overall, it is shown that the solution quality obtained by the mathematical models depends on the size of the problem instance as well as the tool requirements. The precedence-based formulation is superior in general to the position-based and time-index-based formulation for dense problem instances while the position-based formulation works well for sparse problems. With an increasing problem size, the metaheuristic requires significantly less time to find near-optimal solutions than the mathematical models.
    Keywords: mixed integer programming; job sequencing and tool switching; tooling constraints; parallel machines; sequence-dependent setup times.
    DOI: 10.1504/IJOR.2021.10034075
  • Replenishment Decision for Ameliorating Inventory with Time Dependent Demand and Partial Backlogging Rate   Order a copy of this article
    by Vijay Vir Singh, Yusuf Ibrahim Gwanda 
    Abstract: In contrast to deterioration, amelioration refers to a situation where stocked items incur increased value, quantity, or utility while in stock. It is generally seen in poultry, piggeries, wine industries, etc. when these items are kept on the farm or the sales counter, they usually incur increase in quantity and value. In this research, we study an inventory model that outlines the optimal replenishment decision for ameliorating items with a partially backlogged time-varying demand rate to raise productivity and understand opportunity cost due to lost sales. Until recently, most of the research in inventory has been focused essentially on deteriorating inventory, giving little or no attention to its ameliorative nature. Therefore, in this research, we developed an EOQ model for such items with time-dependent demand and partial backlogging rate. Using the differential calculus concept, the various Inventory optimizing functions, like total cost, number of replenishments, backlogging factors, etc. are computed.
    Keywords: Ameliorating Inventory; Time dependent demand; Replenishment decision; Partial backlogging; Lost sales.
    DOI: 10.1504/IJOR.2020.10034078
  • A multi-objective optimization model for production and transportation planning in a marine shrimp farming supply chain network   Order a copy of this article
    by Mr.Chaimongkol Limpianchob, Masahiro Sasabe, Shoji Kasahara 
    Abstract: The traditional operation of marine shrimp farming is widely practiced in Southeast Asia. Giant freshwater prawn farming is one of the main types of farming that also still operates traditionally. Many of these farms operate without advanced techniques for production planning, inventory control, and transportation strategic decisions throughout the supply chain network which are among the most important managerial activities in commercial farming. Maintaining product freshness is of vital importance for aquaculture product Therefore, this paper develops a multi-objective mixed-integer linear programming model for a marine shrimp farming supply chain network design problem. The problem is to plan production and control inventory according to constraints while maximize total profit surplus and minimize shortest route. A multi-echelon, multi-facility, and multi-period mathematical model is proposed such that real conditions are considered. In the end, some numerical illustrations are provided to show the proper Pareto solutions considering all of the objectives
    Keywords: supply chain network; mixed-integer linear programming; marine shrimp farming; giant freshwater prawns; multi-objective optimization; production planning and inventory control; transportation planning.
    DOI: 10.1504/IJOR.2020.10034355
  • Time Paradox in Transportation Problems   Order a copy of this article
    by Sonia, Subramanian Chidambaran 
    Abstract: The boom in E-commerce industry in recent years is reshaping delivery landscape and logistics needs to keep pace with this rapid e-commerce growth. One of the most important customer satisfaction KPIs in the e-commerce industry is to reduce the delivery time and is a key focus area for the market players.The present paper attempts to address this challenge by introducing the concept of a paradox in a time minimizing transportation problem (TMTP) which is a concave minimization problem. The paradoxical situations in cost minimizing transportation problems, fixed charge transportation problems, minimum cost flow problems and in many other variants of transportation problem have been extensively researched and well applied except for TMTPs. After defining the time paradox in a TMTP, we develop the condition of its existence. Further, a comparative study of paradox for a cost minimizing and time minimizing transportation problems has also been carried out.
    Keywords: Time paradox; Time Minimizing Transportation Problem; Bottleneck Transportation Problem.
    DOI: 10.1504/IJOR.2020.10034414
  • A Hybrid Tournament Differential Evolution Algorithm for Solving Optimization Problems and Applications   Order a copy of this article
    by Md Akhtar, Amalesh Kumar Manna, Avijit Duary, Asoke Kumar Bhunia 
    Abstract: The goal of this work is to propose a hybrid algorithm, combining Differential Evolution algorithm and Tournamenting process, for solving constrained and bound-constrained optimization problems. Considering different options of binary tournamenting, six variants of the proposed hybrid algorithm are developed. To test the efficiency and performance of the proposed hybrid algorithm, twelve benchmark optimization problems are considered and solved. From the obtained results of these benchmark problems, proposed six different variants of the hybrid algorithm are compared numerically as well as graphically. From these comparisons, the best variants of the hybrid algorithm for solving constrained and bound-constrained optimization problems are identified separately. Then by using these best variants, three well known engineering design problems are considered and solved. The computational results are compared with the results of some of the existing algorithms available in the literature. In each case, it is observed that the proposed algorithm performs well.
    Keywords: Global Optimization; Constrained Optimization; Bound-constrained Optimization;Differential Evolution; Tournamenting.
    DOI: 10.1504/IJOR.2021.10034505
  • Modeling and simulation of Bernoulli feedback queue with general customers' impatience under variant vacation policy   Order a copy of this article
    by Amina Bouchentouf, Mouloud Cherfaoui, Mohamed Boualem 
    Abstract: This article deals with a feedback queueing system with variant of a multiple vacation policy, balking, reneging, retention of reneged customers. On arrival a customer activates an impatience timer which is generally distributed. If a customer's service has not been completed before the customer's timer expires, the customer leaves the system. It is supposed that the impatience timer depends on the states of the server. The general distribution of impatience times as well as server's states-dependent reneging makes the analysis of the considered model difficult. We establish the equilibrium analysis of the queueing model, we derive its performance measures and examine it by a series of simulation experiments through a discrete-event simulation (EDS). This approach is appropriate for modeling such complex environment, it attempts to replicate the behavior of the system providing the system characteristic estimations.
    Keywords: queueing; vacation; balking; reneging; general customers' impatience; discrete-event simulation.
    DOI: 10.1504/IJOR.2020.10034866
  • Application and Technique of Inventory Control Theory in Pharmaceutical Sciences.   Order a copy of this article
    by Atma Nand 
    Abstract: The pharmaceutical inventory product management poses a unique problem in the hospitals and pharmacy shops. The inventory control theory plays a significant part in a pharmacological business. For every business, the simple and intuitive interpretation of all the available stocks is important. The determination of the importance of a pharmaceutical drug item should also consider other considerations, such as how severely its unavailability would affect patients. All the drugs are associated with an expiry date, so it is necessary to keep minimal safety stocks of pharmaceuticals products. In this article, we have been suitably classified all available pharmaceutical models and discussed in detail. This article is an overall review of most of the available pharmaceuticals Inventory literature.
    Keywords: medicinal inventory; pharmacological inventory; inventory; perishable products; RFID technology.
    DOI: 10.1504/IJOR.2020.10035052
  • A Demand and Supply Chain Inventory Management with Probabilistic and Time Dependent Price   Order a copy of this article
    by Nabendu Sen, Nabajyoti Bhattacharjee 
    Abstract: In real world, it has been a challenging part for the vendors and stockholders selling the perishable product. Especially, when price of the product reduces with time, due to high rate of deterioration and eventually vanishes. The products like vegetable scrap, food products, wood stock, etc. comes under this category. In this paper, we develop a demand and supply chain inventory model with deterioration and exponential demand to maximise the profit of a stockholder selling a perishable product. The selling price is probabilistic and a decreasing function of time so that, after a finite time limit the product has no market value. We consider three probability distributions uniform, triangular and gamma and compare the total profit under three distributions and represent the result graphically. We perform sensitivity analysis and interpret the result both theoretically and graphically. Further, we study the model under different situation and provide managerial implications.
    Keywords: inventory modelling; probabilistic price; total cost; total revenue; total profit; optimisation.
    DOI: 10.1504/IJOR.2021.10035173
  • Theoretical and Empirical Advances in the Assessment of Productive Efficiency since the introduction of DEA: A Bibliometric Analysis   Order a copy of this article
    by Thyago Celso C. Nepomuceno, Ana Paula C. S. Costa, Cinzia Daraio 
    Abstract: The field of productivity and efficiency analysis is growing exponentially, both in terms of new methods and approaches proposed to assess the efficiency of productive decision making units (DMUs), and in terms of innovative and traditional empirical application of existing methods. This survey provides a bibliometric investigation on the advances of the data envelopment analysis (DEA) from the seminal work of Charnes et al. (1978) to the most recent empirical and theoretical contributions. The most influential authors, outlets, contributions and frontier models are investigated through a timeline-based mapping and distance-based clusters of the state-of-the-art in the field of productivity and efficiency analysis with the support of the analytic tools CitNetExplorer and VOSviewer. The visualisation of the DEA relevant extensions is presented with the identification of application gaps and the evaluation of so far proposed methodologies based on a network of co-citations and bibliometric coupling. We provide a valuable reference for researchers to understand and overview potential advances in this field.
    Keywords: heritage of Abraham Charnes; data envelopment analysis; DEA; frontier efficiency; scientific landscape; bibliometric network.
    DOI: 10.1504/IJOR.2020.10035180
  • Sensitivity in Efficiency and Super Efficiency Evaluation: Case of a Private Educational Institution   Order a copy of this article
    by Sandeep Kumar Mogha 
    Abstract: In this paper the performance of academic departments of a selected private institution is assessed for the academic year 2014 to 2015 using DEA-based dual CCR model. At the first stage, we use academic staff and non-academic staff as the input variables and total enrolled students, total pass students, students placed for jobs and research index as output variables. At the second stage, sensitivity analysis is used to assess the super efficiency and the ranking of the academic departments. The new slack model is also applied to measure the impact of slacks on evaluated efficiencies. The results suggest that four academic departments are technically efficient with an average efficiency score of 0.899 and the remaining three are inefficient and operating on increasing returns to scale. The super efficiency scores also suggest the outliers.
    Keywords: dual CCR model; NSM model; sensitivity analysis; NorthCap University; NCU.
    DOI: 10.1504/IJOR.2020.10035261
  • An efficient approach for the Petrol Station Replenishment Problem: An Algerian case study   Order a copy of this article
    by Besma ZEDDAM, Faycal Belkaid, Mohammed BENNEKROUF 
    Abstract: In a logistic process, the goods distribution is an important task. It is also a critical activity that needs to be optimised according to company policy. the petrol station replenishment problem (PSRP) is one of the transportation problems concerned with replenishing a set of fuel stations with the different petroleum products. This problem presents a particular case of the multi-compartment vehicle routing problem (MC-VPR). In this paper, a new bi-objective approach is proposed in order to treat the PSRP. A novel MILP model is proposed based on a real life case study (the Algerian company of fuel distribution NAFTAL). Two objectives are considered: gain maximisation and carbon emissions minimisation. The economic objective is optimised independently of the environmental one, then they are joined by adapting a multi-objective method LP-metric. Finally, computational results are presented in order to show the efficiency of our green approach for a sustainable transportation system.
    Keywords: petrol station replenishment problem; PSRP; multi compartment; carbon emissions; bi-objective; LP-metric.
    DOI: 10.1504/IJOR.2021.10035387
  • The Kalos Balanced: a novel integrated performance assessment and improvement method   Order a copy of this article
    by Seyed Mostafa Bahadornia, Seyed Mohammad Khalili 
    Abstract: These days, managers are surrounded by the extensive spectrum of decision-making environments which are more acute both in quantity and quality. Consequently, it is necessary to utilise expert multiple attribute decision-making methods which are fit to the mentioned environment. To achieve this goal, a novel balanced multiple criteria improvement method, Kalos balanced has been proposed in this article which not only evaluates candidates but also provides a mathematical model for improving the desired candidate. Despite the traditional weight multiplication methods, a novel smooth weighing function has been offered in this study which leads to moderate assessment and balanced improvement based on mathematical proofs. Finally, an example has been assessed and improved based on the mentioned system.
    Keywords: multiple attribute decision making; performance assessment; performance improvement.
    DOI: 10.1504/IJOR.2020.10035391
  • Factors affecting suppliers’ capacity in outsourcing: a study of the Water and Wastewater Company of Iran   Order a copy of this article
    by Hadi Sarvari, Masoud Raeisi Dehkordi, Matteo Cristofaro, Daniel W. M. Chan, Nerija Banaitien? 
    Abstract: What are the major factors able to increase the capacity of suppliers in outsourcing processes? To answer this research question, a three-round Delphi survey was administered to an expert panel composed of 50 industrial experts of the water and wastewater company (WWC) in Iran. The administered questionnaire
    Keywords: water industry; wastewater industry; outsourcing; Delphi; supplier capacity; Iran.
    DOI: 10.1504/IJOR.2021.10035756
  • Hybridized Ant Colony Optimization for the Multi-depot Multi-compartment capacitated arc routing problem   Order a copy of this article
    by Ali Kansou, Bilal Kanso, Adnan Yassine 
    Abstract: This paper considers the multi-depot multi-compartment capacitated arc routing problem. It consists to find a set of vehicle routes with minimal travelled distance that satisfy the demands of a set of customers for several products. This problem has some important applications such as in the fields of transportation, distribution and logistics since companies are increasingly using multiple depots to store their products and separate compartments which are necessary since each product has its own specific characteristics and cannot be mixed during transportation. In this paper, a new approach based on the ant colony optimisation that is hybridised with a simulated annealing algorithm is developed. Computational experiments are performed on a benchmark of instances taken from the literature, and a set of real-life instances, and on another new set of random large-scale instances. The proposed metaheuristic generates high-quality solutions compared to the existing algorithms and particularly the results on the new instances seem promising, purposeful and powerful.
    Keywords: metaheuristic; arc routing problem; multi-depot; multi-compartment; ant colony optimisation; ACO; simulated annealing algorithm.
    DOI: 10.1504/IJOR.2021.10035821
  • Empirical Analysis of Employees’ Commitment, Organizational fitness Elements and Intention-to-Stay in the Malaysian Construction Companies: Mediating Influence of Organizational Commitment   Order a copy of this article
    by Taofeeq Durojaye Moshood, Gusman Nawanir, Fatimah Mahmud 
    Abstract: A concept that is commonly adopted in corporate settings is employee-intention-to-stay. At the same time, a variety of studies have been conducted on this same concept. While a large number of studies relating to management approaches have concentrated on employees motivation, very few studies have been undertaken concerning employees intention to remain in their various companies. Because it is a very significant criterion in deciding a workers stay in the company, this study, therefore, intends to explore the connection between fit organisation elements and staffs intention to remain in the construction industry, with the organisational commitments as a mediating variable. Also, the approach was structured to concentrate on the studys issues and objectives through quantitative analysis design using a positivist research paradigm. The findings showed a direct correlation between organisational fit elements and the workers intention-to-stay in their various companies. Organisational commitment fully mediates the relationship that fits the organisations elements had with the intention-to-stay. Findings suggest that the three components of organisational commitment, as well as workers intention-to-stay, have a high possibility of making employees to stay in their various organisations.
    Keywords: intention-to-stay; fit organisation; organisational commitment; construction industry; PLS-SEM.
    DOI: 10.1504/IJOR.2020.10036157
  • Absolute and Relative Weight Restrictions in DEA - An Comparison   Order a copy of this article
    by Gerald Fugger 
    Abstract: In most data envelopment analysis (DEA) models, the decision maker (DM) only selects inputs and outputs and does not have to make any previous assumptions about the underlying production process. Without additional weight restrictions, the linear program may assign zero weights to inputs and outputs of certain decision-making units (DMUs). Specialised DMUs can be calculated as efficient because only subsets of the data are included in their efficiency calculation. In most cases, however, it is not desirable to ignore inputs or outputs previously selected by the DM, so technical efficiency can overestimate true efficiency. Additional weight restrictions can avoid specialised DMUs, further improve discrimination between DMUs, and allow the implementation of prior knowledge of the production process. This publication provides a comprehensive literature review of relevant studies on additional weight restrictions in the DEA and discusses their implementation and effects. The latter aspects are demonstrated first for five artificial DMUs and then for 1,000,000 simulated DMUs.
    Keywords: data envelopment analysis; DEA; weight restrictions; assurance regions.
    DOI: 10.1504/IJOR.2020.10036541
  • Algorithm for Automation of the Teacher-Course Allotment   Order a copy of this article
    by Sanjeev Kumar, Rakesh Pandey, R.P. Mohanty 
    Abstract: The university course timetabling problem (UCTP) is one of the important scheduling problem, which is a NP-hard category problem. The teacher-course allotment is a sub-problem in this category. It is a time-consuming and complicated exercise in academic institutions and influences the quality of teaching due to subjectivity in allocation decision. This problem is solved manually by holding a number of meetings at institute level and even after such involved interactions, there is no guarantee that courses are allocated in a correct fashion in order to meet program and course objectives as well as for the satisfaction of all stakeholders. To overcome this subjective practice, it is proposed to develop and validate an algorithm to automate this tedious job. The proposed algorithm consists of two phases. In Phase-I, a bipartite graph is used to obtain the teacher-course preferences-based initial solution of the problem, and then conflict free final solution of teacher-course allocation is achieved in Phase-II. To validate, a software application with rich graphic user interface (GUI) is also developed and tested on an Indian university dataset. The results have been implemented with a good degree of stakeholder’s satisfaction.
    Keywords: university course timetabling; teacher-course allotment; bipartite graph; NP-hard; algorithms; scheduling; teaching-learning process.
    DOI: 10.1504/IJOR.2020.10036542
  • A Classical Retrial Queueing Inventory System with Two Component Demand Rate   Order a copy of this article
    by M. Abdul Reiyas, Kathirvel Jeganathan 
    Abstract: We deal a two component demand rate inventory system that composed of two arrival patterns of customers called as homogeneous and non-homogeneous arrival patterns. The homogeneous arrival pattern occurs at zero inventory and the arriving customer compulsorily enters into an infinite orbit. But at the time of positive inventory, the non-homogeneous arrival pattern occurs at a rate which depends on the present stock level (PSL). We set a classical retrial policy (CRP) for an orbital demand and (s, Q) ordering policy to fix for any reorder. In this model, Laplace-Stieltjes transform (LST) is used to investigate the waiting time of a retrial demand under the stability condition and all the necessary system characteristics are measured under matrix-geometric approach and further the sufficient numerical tabulations and illustrations are detailed to explore the goodness of the proposed model.
    Keywords: stock-dependent; retrial queue; waiting time; lead time.
    DOI: 10.1504/IJOR.2020.10036684
  • Evaluation of enablers of supply chain resilience and responsibility in India during large-scale disruptions: An ISM-ANP approach   Order a copy of this article
    by Rohit Sindhwani, Venkataramanaiah Saddikuti, Omkarprasad S. Vaidya 
    Abstract: The healthcare and economic distress caused by large-scale disruptive events is most severe. The recent pandemic, SARS-CoV-2, has affected the entire world with its relentless energy. Only few supply chains (SCs) have remained resilient during disruptions. We highlight that these organisations do not just focus on SC resilience; the innate nature of being responsible has helped them stay afloat. Thus, we understand and identify various enablers of resilient and responsible SCs for survival during large-scale disruptions in India. 15 enablers and 30 sub-enablers for SC survivability are identified from literature and verified by experts. Integrated ISM-ANP approach and MICMAC analysis is adopted to develop a conceptual framework and prioritise enablers for SC survivability. The three most important sub-enablers in near term are advanced tracking and tracing system (0.0807), information sharing of business objectives (0.0776) and multi-way partnership (0.0776), respectively.
    Keywords: survivability; responsible supply chain; supply chain resilience; pandemic disruption; SARS-CoV-2; ISM-ANP; India.
    DOI: 10.1504/IJOR.2021.10036699
  • An optimal pricing and quality assessment model for consumer returns in a multi-period closed-loop supply chain   Order a copy of this article
    by Kamil Ciftci, Yertai Tanai, George R. Wilson 
    Abstract: We propose a framework for a single demand and its returns occurring in a multi-period setting. The goal of this study is to determine price and processing quantities of returns for a retailer when she is faced with stochastic returns and numerous quality conditions for returns specific to a particular period. We formulate the expected profit function of a single demand and its returns over the sales periods and analytically derive the optimum price expression. Furthermore, we develop an extensive numerical experiment to analyse the effect of key parameters on the profit and price. The research herein shows that an increasing number of quality categories for returns improves the total profit significantly over the sales periods. Likewise, we find that the number of quality categories for returns can also affect changes in the price indicating the importance of sensitivity of the retail price to the returns quality.
    Keywords: closed-loop supply chain; returns quality; consumer returns management; multi-period planning; pricing decisions.
    DOI: 10.1504/IJOR.2020.10036702
  • Portfolio Optimization in Emerging Markets: Mean and Median Models Assessment   Order a copy of this article
    by Mai Ibrahim, Mohammed El-Beltagy, Motaz Khorshid 
    Abstract: Portfolio optimisation is instrumental in financial decision making. The basic Markowitz model is considered a milestone in financial theory but many examples including emerging markets were shown not to follow Markowitz’s assumption of normality, hence alternative models have been suggested. The traditional mathematical programming that suits well the Markowitz model falls short in other complex situations of alternative portfolio models. Multi-objective evolutionary algorithms are well suited to solve these models with conflicting objectives regardless of their complexity and mathematical nature. Four models that belong to the mean models are compared to three median models and are formulated as multi-objective problems and solved using the non-dominated sorting genetic algorithm-II. The models are tested on real data of the Egyptian index and compared to two other emerging markets. The results show the outperformance of the median models over the mean models and the tail risk measures over the symmetric risk measures.
    Keywords: evolutionary computations; multi-objective programming; conditional value at risk; CVaR; value at risk; VaR; mean models; median models.
    DOI: 10.1504/IJOR.2020.10037075
  • Multi-item EOQ model for deteriorating items having multivariate dependent demand with variable holding cost and trade credit   Order a copy of this article
    by Dharmendra Yadav, S.R. Pundir, Manisha Sarin 
    Abstract: In the present study, a multi-item EOQ inventory model for deteriorating items is explored by considering customers demand as a function of stock and selling price. Further, holding cost is considered as the function of stock-level and shortages are allowed, which partially backlogged. Further, trade credit policy is one of the attractive policies adopted by the supplier in the competitive market to boost the demand. Two different inventory models are investigated by considering the two situations, namely: a) the end stock level is negative; b) the end stock level is positive or zero. Different lemmas and theorems are provided to develop the search algorithm to obtain the optimal solution. The study shows the importance of multivariate demand and trade credit of the optimal policy of inventory. The feasibility of the proposed model is analysed with the help of a numerical example. Sensitivity is also carried out for critical parameters.
    Keywords: Multi-Item; Multi-variate Demand; Variable Holding Cost; Partial Backlogging; Trade Credit.
    DOI: 10.1504/IJOR.2020.10037238
  • Comparative Analysis between Serial Systems with Cold Standby Units   Order a copy of this article
    by Ibrahim Yusuf, Humairah Baballe Ilah 
    Abstract: This paper studied reliability assessment of three dissimilar systems configured as series-parallel systems. Three probabilistic models are discussed. Each system consists of six units. It is supposed that the failure and repair time of all components are considered to be exponentially distributed. Using linear differential-difference equations, mathematical models for the steady state availability and mean time to failure are derived, examined and compared for each system. Through numerical examples, the systems are compared and ranked to determine the optimal system.
    Keywords: reliability; cost-benefit; serial; cold standby; performance.
    DOI: 10.1504/IJOR.2020.10037239
  • Selection of Materials Formulation for Non-Asbestos Friction Materials using Entropy Weight Based-TOPSIS & COPRAS Multi-Criteria Decision Making   Order a copy of this article
    by Neet Vadgaonkar, Tejas Fulwala, Saurav Mahajani, Dinesh Shinde 
    Abstract: Friction materials are the prime materials which should have higher as well as stable coefficient of friction and lower wear at various braking applications. The demand of these diverse tribological characteristics makes the selection of materials formulation for the friction materials, a critical task. This paper presents an attempt to select the materials formulation for the friction material using two advanced MCDM methods (TOPSIS and COPRAS). Friction materials were prepared at one of the manufacturer from three materials formulation under study (FM01, FM02 and FM03). The experimental set up was developed dedicated to the testing of the friction materials at actual operating conditions. Based on the experimental results, seven criterions were chosen for assessment of the materials formulation in the MCDM approach. TOPSIS and COPRAS methodologies have systematically implemented for evaluation of the materials formulations. Based on the assessments it was concluded that the current approach is useful in evaluation of materials formulation based on the experimental performance. The formulation FM03 was found as a best material formulation among three.
    Keywords: friction materials; materials formulation; Taguchi method; multi-criteria decision making; MCDM; TOPSIS; COPRAS.
    DOI: 10.1504/IJOR.2021.10037243
  • A study on optimization of vehicle allocation for evacuation during a site emergency at a nuclear power plant   Order a copy of this article
    by Anirudh Chandra, Murali Seshadri, Probal Chaudhury 
    Abstract: Indian nuclear power plants have graded engineered safety features because of which accidents with large scale consequences are highly improbable. However, regulatory requirements state the necessity of a site evacuation following a site emergency or an off-site emergency. Planning for this emergency requires allocation of evacuating vehicles. This study provides a simplified model of evacuation, with focus on minimising the travel time. The vehicle allocation was considered to be an optimisation problem. Mixed integer linear programming (MILP) was used to solve this constrained optimisation problem for a particular nuclear facility site. Different evacuation modes were formulated and the evacuation travel times for each mode was estimated. The most reasonable mode of evacuation was found to be a simultaneous supply of vehicles from vehicle depot to facilities, followed by a sequential evacuation of each facility to the exit. This solution reduces unnecessary congestion at exits and also reduces the travel time.
    Keywords: site emergency; evacuation; mixed integer linear programming; MILP; optimisation; emergency response management; nuclear emergency.
    DOI: 10.1504/IJOR.2021.10037361
  • Correlation coefficients in T-spherical fuzzy environment using statistical viewpoint and their applications   Order a copy of this article
    by Dinesh K. Sharma, Surender Singh, Abdul Ganie 
    Abstract: A T-spherical fuzzy set (T-SFS) is a generalisation of spherical fuzzy sets (SFSs), picture fuzzy sets (SFSs), intuitionistic fuzzy sets (IFSs), and fuzzy sets (FSs) in which the sum of the qth power of membership, the qth power of non-membership and qth power of neutrality values is at most one. The correlation coefficient is a crucial tool in fuzzy/non-standard fuzzy theory and has been applied in various fields such as clustering, pattern recognition, medical diagnosis, decision-making, etc. However, the existing correlation coefficients for T-SFSs give only the degree of correlation between two T-SFSs but do not tell us the nature of correlation (negative or positive). In this study, we propose two correlation coefficients for T-SFSs, which not only give the strength of correlation between two T-SFSs but also tell us whether the two T-SFSs are positively correlated or negatively correlated. We also discuss several properties of these correlation coefficients. We apply these correlation coefficients to solve a pattern recognition problem in the T-spherical fuzzy environment and compare the results with some existing measures. Further, by considering linguistic hedges, we theoretically and empirically contrast the performance of the proposed coefficients of correlation for T-SFSs with several existing measures.
    Keywords: correlation coefficient; picture fuzzy set; PIFS; linguistic hedges; spherical fuzzy set; pattern recognition; T-spherical fuzzy set; T-SFS.
    DOI: 10.1504/IJOR.2020.10037551
  • Stochastic closed-loop supply chain models: literature review, recent developments, and future research directions   Order a copy of this article
    by Omar Mohamed Omar Elfarouk, Kuan Yew Wong, Shamraiz Ahmad 
    Abstract: A closed-loop supply chain (CLSC) has been defined as a path that the material flows, starting from suppliers till it arrives at customers as a final product, including product recovery from customers to manufacturers for various usages. A stochastic CLSC handles uncertainty in critical parameters that affect CLSC design. This novel study presents a stochastic CLSC review and categorises uncertainty types applied to stochastic parameters under analysis. Also, the study describes various algorithms that are suitable for solving the different stochastic CLSC models. The research benefits practitioners and researchers by creating guidelines for stochastic CLSC design and discusses the strengths and weaknesses of algorithms used. The results showed the significance of a hybrid genetic, particle swarm optimisation (hybrid GA-PSO) in optimising constrained stochastic CLSC models and the advancement of stochastic CLSC research in the automotive industry. Future research should explore more uncertain parameters, methods of modelling social aspects, and new strategies to implement in stochastic CLSC.
    Keywords: closed-loop supply chain; CLSC; stochastic CLSC; solution algorithms; modelling techniques; uncertainty types; uncertainty parameters; reverse logistics; hybrid particle swarm optimisation.
    DOI: 10.1504/IJOR.2020.10037600
  • A modified presidential election algorithm for optimal tuning of proportional   Order a copy of this article
    by Hojjat Emami 
    Abstract: This paper uses a socio-politically inspired meta-heuristic algorithm based on the behaviour of voters and candidates named modified presidential election algorithm (PEA-II) for proportional-integral-derivative (PID) controller design. The incentive mechanism of PEA-II is enhancing the knowledge sharing and search capability of the canonical presidential election algorithm (PEA) by introducing a new positive advertisement and migration operator. By the new positive advertisement, PEA-II employs the best local and global knowledge of the agents to conduct the searching process in the solution space. The migration operator maintains diversity in the population and keeps the algorithm away from converging too fast before exploring the entire solution space. The proposed approach is evaluated using three well-known PID controller plants. The results show the superiority of the proposed algorithm in comparison with other counterparts.
    Keywords: engineering optimisation problem; control; PID tuning; modified presidential election algorithm; PEA-II.
    DOI: 10.1504/IJOR.2021.10037644
  • Performance of some discriminant analysis techniques   Order a copy of this article
    by Michael O. Olusola, Sidney I. Onyeagu 
    Abstract: This paper re-appraises the use of the minimised sum of deviations by proportion method (MSDP), the linear discriminant analysis (LDA) embodied in Minitab and the logit discriminant analysis (LoDA), for allocating observations into one of two mutually exclusive groups using some examples. In a recent paper, the MSDP was proposed as a means of generating a discriminant function that separates observations in a training sample (or development sample) of known group membership into specified groups. In the MSDP formulation, the sum of the proportion of exterior deviations is minimised subject to the group separation constraints, the normalisation constraint, the upper bound constraints on proportions of exterior deviations and the sign unrestriction vis a vis the non-negativity constraints. The decision rule on group-membership prediction is constructed using the apparent error rate. This study compares the performance of the MSDP with the LDA and LoDA based on their classification accuracy. The obtained results indicate that the LoDA is not suitable for the examples considered and that the MSDP is an appropriate alternative to the LDA.
    Keywords: binary classification; hit rate; linear discriminant function; linear programming; minimised sum of deviation by proportion method.
    DOI: 10.1504/IJOR.2020.10037889
  • Data Envelopment Analysis in Efficiency Measuring of District Central Cooperative Banks in India: a case study   Order a copy of this article
    by Mohd Shamim Ansari, Monika, Irfan Ali 
    Abstract: Over time, cooperative banks lost their dominance in agricultural credit which they enjoyed earlier, and presently they are facing many issues such as deposit management, liquidity management, deterioration in asset quality and so on which affect the performance and efficiency of banks. This study will help the policymakers and management to understand the nature and extent of inefficiency in District Central Cooperative Banks (DCCBs). Efficiency is essential for profitable growth of any decision-making units (DMUs), which will ensure value appreciation and survival in the long run. This paper is an attempt to measure the technical efficiency of DCCBs of Uttar Pradesh by applying Charnes, Cooper and Rhodes (CCR) model (Charnes et al., 1978) of data envelopment analysis. For the study purpose, all the 50 DCCBs operating in the Uttar Pradesh state of India has divided into 18 divisions as per the zonal classification of Uttar Pradesh administration. The estimated result shows that two-division are relatively most efficient, while three-division are less efficient. By improving the management of NPA, deposit management, increasing borrowing, loans and advances, less efficient banks can improve their efficiency.
    Keywords: ooperative; non-performing asset; NPA; technical efficiency; Charnes; Cooper and Rhodes; CCR model; data envelopment analysis; DEA.
    DOI: 10.1504/IJOR.2020.10037905
  • Inventory Policy Determination in MSMEs using Intuitionistic Fuzzy Sets based on Learning Aided Decision Support System   Order a copy of this article
    by Mahuya Deb, Kandarpa Kumar Sarma 
    Abstract: The successful operation of micro, small and medium enterprises (MSME) requires an effective supply chain linking manufacturers and distributors so as to minimise cost, reinvent channel models, and optimise collaborative relationships. In order to overcome the uncertainty present in this chain, inventory management policies are adopted which are crucial for enhancing, smooth production plans, and lower operation costs. Intuitionistic fuzzy (IF) set is considered to be an appropriate tool to model uncertainty in the chain. This paper deals with inventory policies regulated by IFS which would be applicable to the MSMEs. Normalised Euclidean distance method is used to measure the difference between each enterprise and each inventory policy respectively so as to select the best set of inventory management policy suitable for a unit. Further, the work involves the design of a decision support system (DSS) based on learning aided technique which provides an automated approach to the work.
    Keywords: micro; small and medium enterprise; MSME; inventory policy; decision support system; DSS; Euclidean distance; triangular intuitionistic fuzzy number; TIFN.
    DOI: 10.1504/IJOR.2020.10037911
  • How to Bring Manufacturing Back?   Order a copy of this article
    by Ziping Wang, Huafan Ma 
    Abstract: Moving manufacturing back to the US has been in many fierce debates. While many believe that reshoring is beneficial to the US through creating more jobs, our paper intends to gain more insights into this issue by studying a sourcing game between global firms and governments. Global firms may choose between offshoring and reshoring. Governments, as tax policy makers, aim at improving social welfare. First, our analysis indicates that firms may choose reshoring even if there are cost advantages to offshoring. Secondly, while reshoring may increase employment in the US, it may also have a negative effect on the overall social welfare. Thirdly, when the labour cost in the US is moderately higher, the government may launch new tax policies to motivate reshoring and improve social welfare. Finally, numerical examples demonstrate that reshoring improves social welfare in labour-intensive industry, while tax policies may curb such improvement with high tax rates.
    Keywords: reshoring; supply chain management; tax policy; social welfare; production function.
    DOI: 10.1504/IJOR.2021.10038294
  • A Nonlinear Goal Programming Approach with a Modified Search Algorithm to Achieve Student Outcomes in College Education   Order a copy of this article
    by Murat Cal, Sibel Atan 
    Abstract: We introduce a modified search algorithm to solve a nonlinear goal programming model to achieve multiple goals to the highest extent while minimising the total deviation from these targeted goals. We develop our model in an education environment that implements gamification in teaching hours, and learning outcomes are evaluated by assessments. Our parameters are then evaluated through experimental analysis and we provide insights on their accuracy. It is shown that our algorithm finds solutions within 1 to 10 per cent of the optimal solutions for different intervals, and these solutions are found instantaneously. Our model answers how much time of a teaching hour should be allocated for gamified elements, and how a game-based environment can be established together with an evaluation system. The study in that sense is unique as it combines a nonlinear goal programming model with gamification in teaching and it provides a framework to evaluate student outcomes to cope with educational objectives.
    Keywords: nonlinear goal programming; heuristic algorithms; education theory; optimisation.
    DOI: 10.1504/IJOR.2021.10038481
    by Amit Kumar Saraswat, Ashish Sharma 
    Abstract: Growing items like live stocks, chicks, etc. gain weight in the growing phase but some of them are lost due to mortality. In the selling phase, some inventory lost due to deterioration. Such aspects make procurement decision quite difficult for these items. In the light of such aspects, we developed an inventory model for the growing items with price dependent demand, mortality and deterioration. Shortages are partially backlogged. Our aim is to optimise the total cost by determining the optimal ordered quantity and total cycle length. Convexity of the cost function with respect to the decision variables has been discussed analytically. Solution procedure along with numerical example at different percentage of backlogged quantity is provided to show the applicability and validity of our model. Sensitivity analysis shows that total cycle length is the most sensitive among all the decision variables and parameters.
    Keywords: growing items; price dependent demand; deterioration; mortality; inventory model.
    DOI: 10.1504/IJOR.2021.10038488
  • Optimal Warehouse Location and Size In Practice   Order a copy of this article
    by Richard Caron, Tareq Oshan 
    Abstract: Facility location decisions are crucial in supply chain network design because they affect a firm’s profitability and success. We present an example of the optimal selection of the location and size of warehouses for a Canadian company with operations across the nation. We begin with a description of the optimisation model that will be used to determine the size and location of new warehouses as well as the allocation of branches to warehouse. We will then discuss the characteristics of the company and explain the challenges that were overcome in fitting the application to the model. We continue with an analysis of the solutions and follow that with a summary of lessons learned.
    Keywords: supply chain network design; application; case study.
    DOI: 10.1504/IJOR.2021.10038494
  • Joint inventory, promotion and preservation decisions for deteriorating items with maximum lifetime and stochastic demand under two-level partial trade credit   Order a copy of this article
    by Hardik Soni, Ashaba Chauhan 
    Abstract: This study models a joint inventory, promotional effort and preservation decision-making problem for deteriorating items with maximum lifetime under a two-level partial trade credit and allowable shortages. This paper considers a supplier-retailer-customer supply chain model which allows: 1) for settling the cost of purchasing, the supplier offers a partial trade credit to the retailer and at the same time retailer offers a partial trade credit to the customer; 2) the upstream(supplier-retailer) credit period increases sales of the supplier and revenue of the retailer, the downstream (retailer-customer) credit period not only lifts demand but also the opportunity cost; 3) the deteriorating product not only deteriorate continuously but also it have maximum lifetime and to reduce the deterioration rate we use the preservation technology; 4) price and promotional effort dependent random demand; 5) shortages are considered. The objective is to find the optimal promotional effort, preservation technology investment, length of time for the inventory level reaches zero and replenishment cycle strategies while maximising the total profit per unit time. Numerical examples are included to illustrate the algorithmic procedure and the effect of key parameters is studied to analyse the behaviour of the model.
    Keywords: inventory; deterioration; preservation technology; promotion; maximum lifetime; partial trade credit; supply chain.
    DOI: 10.1504/IJOR.2020.10038506
  • De-i-fuzzification of Linear Interval-Valued Intuitionistic Fuzzy Number, and its Application in Operation Research Arena   Order a copy of this article
    by Sankar Prasad Mondal, Avishek Chakraborty, Shilpi Pal, Shariful Alam 
    Abstract: In this article, we have envisaged the linear interval valued intuitionistic fuzzy number (IVIFN) from various viewpoints. We have introduced the technique of ranking by using the concept of distance measure of linear interval valued intuitionistic fuzzy number. Additionally, the concept of de-i-fuzzification is introduced here using two disjunctive logical approaches and its result is explained in this article which will help us converting a linear interval valued intuitionistic fuzzy number into a crisp number. Lastly, the validation of the model is observed by using two different real life problems firstly, in inventory control and secondly, in transportation arena. The paper suggests two different methods of de-intuitification in linear interval valued intuitionistic fuzzy domain and the comparison between the two methods by using a suitable algorithm has been observed in above real life scenarios that connects all invented results.
    Keywords: inear IVIFN; ranking; distance measure; de-i-fuzzification; inventory control; transportation problem.
    DOI: 10.1504/IJOR.2020.10038562
  • Statistical distribution and analysis of secondary queue of railway passengers   Order a copy of this article
    by S.M. QASIM, Jamal Ahmad Farooqui 
    Abstract: Millions of passengers commute through trains in India every day. Still, thousands of waitlisted tickets are cancelled due to the non-availability of accommodation in the desired train on a particular day. Such cancellations result in dissatisfaction and discomfort to the waitlisted ticket holders and loss of business to Indian Railways. The queue of waitlisted ticket holders, called secondary queue, form when the berths in demand are less than the number of berths available in the desired class of accommodation in a particular train on a specific date. The small number of passengers from this queue are served with confirmed tickets surrendered by the passenger from the primary queue holding confirmed tickets. This paper, a portion of a larger study, attempts to identify the statistical distribution of arrivals and service for the secondary queue. Stationarity and interdependence have been examined for inter-arrival time and service time in context of sleeper (SL) class accommodation of Vaishali superfast express train. This has been found the secondary queue of Indian Railways advanced reservation passenger system follows G/G/C/K model of queuing theory. The results are expected to help the Indian Railways determine various queue parameters and hence optimise the system.
    Keywords: railway reservation; primary queue; secondary queue; statistical distribution; stationarity.
    DOI: 10.1504/IJOR.2021.10038639
    by P. Raghuram, Anuj.S Jain, Souryadeep Mazumder 
    Abstract: Warehouse management is an integral part of the supply chain and optimisation of warehouse operations can minimise redundant movements of pickers and can reduce processing time, thereby maximising the profits. In this paper, our objective is to develop a simulation model to find the optimal number of forklifts and arrival rate of goods by considering various factors like distance travelled by pickers, picker utilisation, storage and retrieval times. The warehouse layout is found through the number of racks, number of vertical levels and aisle width using genetic algorithm in MATLAB. The objective function is to minimise the total operational costs considering space and arrival constraints. The warehouse design parameters after optimisation are used in the simulation model to develop a new layout. The number of pickers and arrival rate of goods is obtained, analysed and compared. It is observed that further reduction in the aforementioned factors are obtained.
    Keywords: warehouse optimisation; order picking; storage; handling; agent-based modelling; genetic algorithms.
    DOI: 10.1504/IJOR.2021.10038694
  • An Optimization Approach in Trough Angle Selection of Conveyor Five Roll   Order a copy of this article
    by Theerasak Srimitrungroj, Tarit Rattanamanee 
    Abstract: This paper study the optimisation techniques by using numerical method for analysing selection problems, choosing the size, length and angle of inclination for the conveyor belt roller of conveyor five rolls to obtain the maximum material transfer rate. The mathematical model is formulated as nonlinear programming. The Lagrange multiplier technique is used to solve the solution. The numerical result shows that setting trough set angle number two (?2) twice as trough set angle number one (?1) yields the maximum material transfer rate.
    Keywords: trough angle selection; belt conveyor; bulk material handling; optimisation.
    DOI: 10.1504/IJOR.2021.10039045
  • Distribution of occupied resources on a fractional resource sharing in a queueing system   Order a copy of this article
    Abstract: Many server systems can share their resources by fractional way not discrete. It can be found in major cases of communication systems sharing power, spectrum or bandwidth resources for example. The objective of this work is to build analytical expressions of the amount of occupied resources in a structure modelled as queueing system. The queue server shares its resources to customers that request services to him. Both infinite and finite capacity are highlighted and the requested resources can be fractional. The amount of occupied resources as real-valued random variable is characterised by its distribution functions that we proposed in this paper. They are validated by simulations, and then can be used to predict the performances of such system or to dimension the appropriate needed capacity. Impacts of system load factor and system capacity has been also analysed.
    Keywords: queueing; dimensioning; load factor; resource occupation; resource sharing.
    DOI: 10.1504/IJOR.2021.10039107
  • Operational Performance Evaluation & Efficiency Assessment of Thermal Power Sectors of Pakistan Using Data Envelopment Analysis   Order a copy of this article
    by Sadam Hussain, Faheemullah Shaikh, Laveet Kumar, Zulifqar Ali 
    Abstract: Energy is a life-line for almost all human activities and progress. Retrospective analysis of the increase in energy demand shows that meeting future energy requirements would be one of the severe problems to sustain the socio-economic activities in the world. The aims and objective of this study is to evaluate the power generation capacity of different thermal power plant in Pakistan using data envelopment analysis (DEA). Performance comparison includes refined furnace oil versus natural gas versus dual fuel versus coal and also GENCOs versus IPPs versus K-Electric power plants. Finding from the results indicates that natural gas outperformed as compared with refined furnace oil-based power plants dual fuel-based, coal-based thermal power plants. Results show that the performance of IPPs is high in comparison to KElectric and GENCOs. Accordingly, based on these results several policy implications have been planned to increase the performance of available thermal power sector in Pakistan.
    Keywords: operational performance; efficiency assessment; data envelopment analysis; thermal power plants; Pakistan.
    DOI: 10.1504/IJOR.2021.10039185
  • Using Constructivist Multi Criteria Decision Aid to Evaluate the Workforce Sizing in Public Organizations: The case of a Brazilian University   Order a copy of this article
    by Juliana Flores, Andre Longaray, Leonardo Ensslin, ADEMAR DUTRA, Sandra Ensslin, Vilmar Tondolo 
    Abstract: When addressing staff sizing management, the workforce that is required to meet the institutions objectives must be quantitatively and qualitatively identified and analysed, taking the institutions environment into account. Most studies concerning workforce sizing in learning institutions are limited to measuring faculty performance. Therefore, a gap in the literature exists concerning a performance evaluation of the sizing procedures for the administrative workforce at universities. We developed model to determine the requirements for a workforce sizing at a Brazilian public university. The research was classified as applied, exploratory, and descriptive, and it was divided into qualitative and quantitative steps. Utilising a constructivist multicriteria decision aid approach, 83 primary evaluation elements and 119 descriptors were identified. The status quo analysis revealed three areas with performance levels significantly lower and 50 indicators that are at a compromising level, for which action plans were proposed. The built model supported the manager in the performance evaluation of the staff sizing procedures.
    Keywords: performance evaluation; MCDA-C; staff sizing; universities; human resources.
    DOI: 10.1504/IJOR.2021.10039187
  • A separable programming approach for resource optimization in controlling epidemics   Order a copy of this article
    by Anuradha Mahasinghe, Sanjeewa Perera, Hasitha Erandi 
    Abstract: Optimal resource allocation in controlling epidemics is a topic of importance, in particular to health-planners in developing countries. Commonly practised resource allocation criteria depend on some trivial statistics, hence critical factors such as human mobility are often ignored in making health decisions. In this work we propose to incorporate inter-regional mobility factor into the decision-making process. Starting from the well-known compartment models for epidemic transmission, we formulate a nonlinear optimisation problem for the regional allocation of resources, aimed at minimising the total number of infectious persons in the country. Computational challenges in finding the global optimum to this problem are overcome by restating it in the form of a separable program, which is eventually reduced down into an efficiently solvable mixed-integer linear program. We derive numerical results by applying our solution techniques to relevant data on dengue transmission in Sri Lanka. Finally, we interpret the results and show that resource allocations are inadequate unless the mobility factor is taken into account.
    Keywords: resource optimisation; separable programming; linear programming; epidemic models.
    DOI: 10.1504/IJOR.2021.10039192
  • Evaluation of Student’s University Selection Decision-Making using an Instilled Fuzzy AHP Approach   Order a copy of this article
    by Neha Gupta, Mohini Agarwal, Pratibha Garg 
    Abstract: The purpose of this study is to identify and rank the potential factors that can benefit the students in making an optimal decision for university selection in learning process. To achieve this purpose, informational architype, along with the questionnaire, was circulated, which was followed by analysing the responses. For the data collection purpose, a structured questionnaire was constructed, and responses of 100 prospective students of Indian origin who are likely to take admission in universities were recorded. After reviewing the literature, six prominent factors have been considered, and AHP followed by FAHP techniques have been employed for computing weights corresponding to assumed factors. The results indicated that the highest weightage had been given to location followed by fee structure in both the cases. Further, utility theory has been used, which shows the superiority of FAHP over AHP analysis.
    Keywords: university selection; decision-making; analytical hierarchy process; AHP; fuzzy analytical hierarchy process; FAHP; utility theory.
    DOI: 10.1504/IJOR.2020.10039273
  • A linear programming model for airline schedule recovery after disruption   Order a copy of this article
    by Jakob Kotas 
    Abstract: We present a decision support framework for optimal flight rescheduling on an airline’s day of operations under unanticipated system disruption. We consider disruptions which add an unforeseen need to extend each aircraft’s turnaround time on the ground, not necessarily uniformly across all flights or airports in the system. Our model optimally reschedules remaining flights of the day to minimise system delays and cancellations. The model is formulated as a mixed integer linear program. We prove that structural properties of the model allow it to be decomposed into a finite set of linear programs, and a computationally tractable algorithm for its solution is described. The model is solvable exactly and quickly, even for large airlines. Numerical simulations are presented for a case study of a winter weather event impacting Horizon Air, a regional airline based in the Pacific Northwest of the USA.
    Keywords: decision support framework; disruption management; scheduling; airline scheduling; airline operations; linear programming; mixed integer linear programming; winter weather; snow; de-icing.
    DOI: 10.1504/IJOR.2020.10039384
  • Transient analysis of various vacation interruption policies in a Markovian queue with differentiated multiple vacations   Order a copy of this article
    by A. Azhagappan, T. Deepa 
    Abstract: Two different types of interruptions (partial and complete) of server’s vacation are discussed in this research work along with two different types of vacations (types 1 and 2). The transient analysis of an M/M/1 queueing model with differentiated multiple vacations, partial and complete interruption of vacations is carried out. Two types of vacations are studied in this research work. Type 1 vacation is taken after serving all the customers in the system exhaustively. Type 2 vacation is resumed after returning from type 1 vacation and finding the empty system. Partial interruption is the one in which the interruption happens only in type 2 vacation whereas complete interruption can occur in both types 1 and 2 vacations. The system size distributions are derived using generating function and Laplace transforms under transient case. The average and variance are also obtained. Further, numerical simulations are presented.
    Keywords: the M/M/1 queue; differentiated multiple vacations; partial and complete interruption of vacations; transient probabilities.
    DOI: 10.1504/IJOR.2021.10039385
  • Improving healthcare services in Trauma Emergency Centre for patient safety under COVID-19 pandemic crises   Order a copy of this article
    by Dilbagh Panchal 
    Abstract: This work presents an application of structured decision support model for improving health service related quality in Indian Trauma Emergency Centre (TEC) under COVID-19 pandemic crisis. Fuzzy failure mode and effect analysis (FMEA) tool built decision support model has been applied for pinpointing the most precarious causes/barriers which result in poor health service quality. Various causes/barriers responsible for poor service quality associated with TEC has been listed under FMEA sheet thorough carrying a brainstorming session with hospital management. Feedback in the form of linguistic ratings were filled by the three experts against three risk elements. For overcoming the drawback of traditional FMEA approach in term of uncertainty/vagueness effect and same ranking problems, fuzzy FMEA was applied and the fuzzy output-based rankings are equated with traditional FMEA approach-based results in order to take necessary action for minimising the total service time for patient’s safety during this pandemic period.
    Keywords: trauma emergency centre; patient safety; COVID-19; health service; fuzzy FMEA; service time.
    DOI: 10.1504/IJOR.2021.10039386
  • Integrated Bioethanol-Gasoline Supply Chain evolved by changing US government policies   Order a copy of this article
    by Davoud Ghahremanlou, Wieslaw Kubiak 
    Abstract: COVID-19 travel restrictions caused gasoline consumption reduction. Global warming and crude oil dependency had already driven policymakers to make policies to reduce consumption of gasoline. The US had created policies to regulate bioethanol production and blending with gasoline. Although these regulations created opportunities, they also placed new burdens on the obligated parties. The effect of the policy change on the integrated bioethanol-gasoline supply chain (IBGSC) is therefore important for both government and business to study to reduce bankruptcies in current market refineries and bio-refineries. To that end, we extend the IBGSC studied by Ghahremanlou and Kubiak (2020a) to include both first and second generation bioethanol, import and export, and existing infrastructure. We develop a two-stage stochastic programming model. Solving this model leads toward solving NP-hard problems, therefore, we develop an algorithm and overcome the computational complexity. The ELM can be employed to evaluate sustainability of the IBGSC under different policies.
    Keywords: COVID-19; supply chain management; operations management; location-allocation; sustainability; stochastic programming; oil war.
    DOI: 10.1504/IJOR.2021.10039501
  • A Mixed-Integer Quadratic Programming Production-Transportation Problem   Order a copy of this article
    by Dominic Otoo, Bernard A. Adjei, Sampson T. Appiah 
    Abstract: One economic challenge encountered by most companies that produce and haul their local products to independent distributors is accurately identifying the optimal routes to each distribution centre and assigning production machinery. The authors in this paper have collaboratively developed a mixed-integer quadratic model that optimally assigns machines and vehicles to produce and properly distribute goods to multiple distributors in 105 locations dotted across the 16 regions of the country based on their demand constraints. Our formulated model and analysis show that the production cost accounts for 0.7933 and transportation cost accounts for 0.2066 of the total cost. Our results have convincingly shown a cost reduction of 10% and 25% respectively in terms of production and transportation cost as compared to the cost currently operated by the two local factories under consideration.
    Keywords: optimal; integer programing; production; transportation; distributors.
    DOI: 10.1504/IJOR.2021.10039544
  • A two-level supply chain with price sensitive random demand, random yield, inspection, and rework process   Order a copy of this article
    by Farzaneh Mohammadia, Maryam Esmaeili, Jiang Zhang 
    Abstract: This paper studies a two-level supply chain consisting of a manufacturer and a retailer. The manufacturer’s production output follows a random process due to the presence of defective goods. The retailer faces random price dependent customer demand. We propose that the manufacturer can reduce the number of defective items manufactured by performing inspection and rework. We first consider both decentralised and centralised supply chain models to determine the manufacturer’s production size, the retailer’s order quantity, the manufacturer’s rework cost, and the retailer’s sales price, as well as the retailer’s and the manufacturer’s expected profit. We then propose a buy-back contract to coordinate the supply chain. We also use numerical examples to illustrate our findings and perform sensitivity analysis on the price elasticity of the demand and tensile coefficient of rework cost.
    Keywords: random yield; random demand; rework process; pricing; supply chain; buy-back contract.
    DOI: 10.1504/IJOR.2020.10039635
  • A Metaheuristic for the Multiple Minimum Latency Problem with the Min-Max Objective   Order a copy of this article
    by Ha-Bang Ban 
    Abstract: The multiple minimum latency problem with the min-max objective (mMLPMM) is an extension of the multiple minimum latency problem (mMLP). The mMLPMM requires to find a tour that aims to equally distribute the latency among routes by minimising the maximum route latency. To solve medium and large size instances, an effective metaheuristic algorithm is introduced, which combines greedy randomised adaptive search procedure (GRASP) for an initial solution construction, and general variable neighbourhood search (GVNS) for solution improvement. The proposed algorithm is tested on the benchmark instances derived from the literature. The results indicate that the GRASP-GVNS can produce efficient and effective solutions for the mMLPMM at a reasonable computation time.
    Keywords: multiple minimum latency problem with min-max objective; mMLPMM; greedy randomised adaptive search procedure; GRASP; general variable neighbourhood search; GVNS; metaheuristic.
    DOI: 10.1504/IJOR.2021.10039701
  • Dynamic Programming approach to achieve higher view-count for YouTube Videos   Order a copy of this article
    by Mohammed Shahid .Irshad, Adarsh Anand, Sankar Kumar Roy 
    Abstract: Broadcast media telecasts their programs at fixed timing, which forces the viewer to be presented at the time of broadcast whereas online streaming platforms allows viewers to watch videos any time. YouTube being the free streaming platform attracts lot of viewers where short videos are uploaded. With its growing popularity content creators have started uploading series of scripted or non-scripted content (video) in episode forms known as a web series. A web series usually has 5 to 10 episodes, and each episode is uploaded independently. The producers desire maximum view-counts with minimum promotional expenditure on each web series. This paper presents an optimisation modelling framework for budget allocation in order to achieve a greater number of view-counts. The proposed framework takes into consideration the aspiration level for the episodes wherein; dynamic programming approach has been utilised to numerically illustrate the validation on two web series on YouTube.
    Keywords: budget allocation; dynamic programming; view-count; web series; YouTube.
    DOI: 10.1504/IJOR.2020.10039748
  • An Optimization-Simulation Framework for Integrated Inventory and Cash Replenishment Problem of Automated Teller Machines in India   Order a copy of this article
    by Ankush Kamthane, Prashant Singh, Ajinkya N. Tanksale 
    Abstract: This work is motivated by the problem of managing inventory and the optimal replenishment schedule for a network of automated teller machines (ATMs) in India The objective is to minimise the occurrences of shortages at the ATMs and in turn to achieve a higher service levels while minimising the cost of holding inventory and replenishment of ATMs The problem is casted as a rich variant of inventory routing problem with several practical restrictions such as maximum inventory at the ATMs. A two-phase iterative decomposition heuristic is proposed to efficiently solve the practical size problem instance. The computational experiments based on synthetic data are conducted to assess the efficiency and effectiveness of the proposed solution approach and a case of Varanasi city in India is presented for the analysis. The results shows the effectiveness of our proposed approach over the conventional replenishment policies.
    Keywords: automated teller machine; ATM; inventory routing problem; IRP; mixed-integer programming; heuristic; simulation.
    DOI: 10.1504/IJOR.2021.10040003
  • Application of Fintech in Financial Inclusion: A Bibliometric Review   Order a copy of this article
    by S.M.Rakibul Anwar, Riduanul Mustafa, Md. Abul Kalam Azad 
    Abstract: This study examines the literature on fintech application in financial inclusion applying a citation mapping-based review technique-bibliometric analysis. The results of bibliometric review are then manually validated with content analysis. A total of 46 published documents from Scopus database are examined. Major findings from bibliometric review reveal three distinct research areas in literature: 1) generic application of fintech; 2) methodological and implication of fintech in credit scoring; 3) country performances. Future research directions are also identified.
    Keywords: fintech; financial inclusion; bibliometric; financial exclusion.
    DOI: 10.1504/IJOR.2021.10040041
  • A Modified Method for Solving the Unbalanced TP   Order a copy of this article
    by Anju Khandelwal, Avnish Kumar 
    Abstract: Most of the methods suggested for the unbalanced transportation problems, in the literature are based on an adding of dummy source/destination with zero cost to make it balance transportation problem first and then to obtain the basic feasible solution (BFS). The present paper suggests a modified algorithm for finding a BFS to an unbalanced transportation problem through which we get the optimum solution without adding the dummy source/ destination. The method is presented in an algorithmic form and implemented on several sets of input data to test the performance and effectiveness of the algorithm. A comparison is also made with the existing approach and it is found that the suggested algorithm shows better performance.
    Keywords: unbalanced transportation problem; UTP; Vogel’s approximation method; VAM; initial basic feasible solution; IBFS; basic feasible solution; BFS; optimal cost.
    DOI: 10.1504/IJOR.2021.10040356
  • Decision Making and Martial Arts   Order a copy of this article
    by José Soeiro Ferreira  
    Abstract: Martial arts (MAs) are a global training system that goes far beyond physical preparation and self-defence. They have been known for a long time, and their wisdom and impact are impressive. The paper illustrates matters about MAs which are relevant to decision making (DM). The recognition of the limitations of the sole dependence on physical ability (hard approaches) is a breakthrough in MAs. The pillars of body and technique are not enough to reach a global vision and overcome severe problems. MAs are committed to mastering faculties linked to intuition, emotions, and thought-free operations, signifying the pillar mind. These revelations have insightful implications for DM and the promptness in approaching the growing complexity of decision problems. Special attention is devoted to the mind, representing a soft paradigm, emphasising the human dimension, integrating intuition and complying with ethics. Finally, the paper delineates a MAs way to improve DM as science and art.
    Keywords: decision making; martial arts; operational research; hard and soft methodologies; intuition; emotions; ethics.
    DOI: 10.1504/IJOR.2021.10040444
  • Locating a Rectangular Barrier Facility on the Plane: A Bi-Objective Approach   Order a copy of this article
    by Mustafa Canbolat, George O. Wesolowsky, Michael Von Massow 
    Abstract: We study the problem of finding a minimax location for a rectangular barrier facility on the plane and simultaneously minimising the interference of the barrier facility to the interactions among the existing facilities using rectilinear distances. This provides an ex post opportunity to modify an existing network or layout while minimising the disruption. The problem is formulated as a bi-objective problem and a mixed integer program is proposed as a solution methodology. A simulated annealing algorithm is presented for an extension of the problem where expropriation or removal of existing facilities is also possible. We consider expropriation or removal of existing facilities only if such policy is necessary or cost-beneficial.
    Keywords: planar facility location; facility layout; barriers; expropriation; optimisation; heuristics.
    DOI: 10.1504/IJOR.2021.10040445
  • Redundancy optimization for tandem production systems under queueing and availability constraints   Order a copy of this article
    by Fong-Fan Wang 
    Abstract: Equipment selection is an important issue during the initial phases of implementing a production system. In this paper, one type of product manufactured on a production line composed of several stages with redundant and unreliable machines is studied. Assume available version of machines with respective cost and operating characteristics are available for each subsystem, the objective is to minimise the purchase cost subject to average system availability and total waiting time constraints. We propose two techniques for evaluating the studied system. Using simulation, we justify that matrix analytical method can approximate the system behaviour better than another method based on Allen-Cunneen approximation. We employ three meta-heuristics, including genetic algorithm, particle swarm optimisation and simulated annealing to optimise the system structure. We provide numerical examples for performance evaluation and comparison of the efficiency and efficacy of the proposed optimisation methods.
    Keywords: tandem production system; redundancy optimisation; matrix analytical method; metaheuristics.
    DOI: 10.1504/IJOR.2021.10040597
  • A new Secant-like quasi-Newton method for unconstrained optimization   Order a copy of this article
    by Issam A.R. Moghrabi  
    Abstract: The secant equation traditionally constitutes the basis of quasi-Newton methods, as the updated Hessian approximations satisfy the equation on each iteration. Modified versions of the secant relation have recently been the focus of several papers with encouraging outcomes. This paper continues with that idea where a secant-like modification that utilises nonlinear quantities in constructing the Hessian (or its inverse) approximation updates is derived. The technique takes advantage of data readily computed from the two most recent steps. Thus, it offers a substitute to the secant equation to produce better Hessian approximations that result in accelerated convergence to the objective function minimiser. The reported results provide adequate evidence to suggest that the proposed method is promising and deserves attention.
    Keywords: quasi-Newton methods; secant-like methods; BFGS; unconstrained optimisation; multi-step methods.
    DOI: 10.1504/IJOR.2021.10040598
  • An inventory model for perishables with fixed storage life and diminishing ability to buy in their life expectancy.   Order a copy of this article
    Abstract: In present market scenario, health-conscious customers embrace a policy to purchase a perishable product with more storage life as it is fresher and can be stored for successful time. Additionally, a large variety of goods in market influence customers to buy the most recent and quality improved items propelled by the companies. In this paper, these two relevant factors are incorporated and an optimal inventory model for the demand pattern depending on the willingness of buyers under fixed storage life has been developed. The demand process includes the willingness of customers to buy such items subject to their desired degree of satisfaction. To study such demand fluctuation, a stochastic mathematical model using the Gaussian distribution has been presented. The optimised values of parameters have been determined and the results are analysed with the help of numerical example. A sensitivity analysis for the involved parameters over optimal results is also provided.
    Keywords: inventory; stochastic model; storage life; perishable; Gaussian distribution; willingness; life expectancy.
    DOI: 10.1504/IJOR.2021.10040828
  • A Fuzzy Random Periodic Review Mixture Inventory Model with Backorder Price discount   Order a copy of this article
    by Wasim F. Khan, Oshmita Dey 
    Abstract: In this paper, a periodic review inventory model with a mixture of backorders and lost sales is developed under mixed fuzzy random environment. It is assumed that the supplier provides some price discount to control the backorder rate and gives an incentive to the customers to wait for the arrival of their orders rather than take their orders elsewhere. The annual customer demand is considered to be continuous fuzzy random variable following normal distribution. The model is analysed under three scenarios no price discount, fixed price discount and controllable price discount. An algorithm is presented to simultaneously determine the optimal values of the review period, the target inventory level and the backorder price discount so that the total annual cost is minimised. Numerical examples show that the case of controllable backorder price discount leads to the system incurring lowest operational costs.
    Keywords: inventory; periodic review; backorder price discount; continuous fuzzy random variable; normal distribution.
    DOI: 10.1504/IJOR.2021.10040829
  • “Novel Approach to Data Envelopment Analysis   Order a copy of this article
    by Drinko Kurevija 
    Abstract: This article analyses the performances of the Austrian Research Promotion Agencys (ARPA) general program by applying a novel approach to data envelopment analysis (DEA) namely the adjusted DEA (A-DEA). Considering the previous findings of Sowlati and Paradi (2004) by defining a new practical frontier and utilising management input, a modified linear programming model and a methodology for improving the efficiency of empirically efficient units was applied. The aim was to find the output for the novel different units in order to identify an alternative frontier of both already empirically efficient and these new DMUs considering the performances of ARPAs general program.
    Keywords: data envelopment analysis; DEA; novel DEA; unobserved DMUs; weight restrictions; multicriteria decision making; stochastic frontier analysis; programs; projects; efficiency.
    DOI: 10.1504/IJOR.2021.10040904
  • A game theory framework for newly launch greening product in two-echelon supply chain   Order a copy of this article
    by Sukhendu Bera, Raghu Giri, Dipak Kumar Jana, KAJLA BASU, Manoranjan Maiti 
    Abstract: A two-echelon supply chain model is considered where one manufacturer and one retailer reduce the customers’ sensitivity to the product price and stimulate the demand of the product by introducing facilities such as product’s greenness, service level and promotional effort. They share the costs jointly on the above facilities following some agreements. The models are formulated as profit maximisation problems for the whole system and chain members under centralised and decentralised decision scenarios and solved using game theoretical approach. As particular cases, several models with greenness, service level and promotional effort separately (one or two facilities at a time) are formulated and solved. Finally, numerical experiments are conducted and some managerial decisions are presented from the optimal results and sensitivity analyses. It is demonstrated that the greenness, service level and promotional effort activities stimulate higher demand and fetch more profits for supply chain and its members.
    Keywords: supply chain; greening investment; promotional effort; service level; Stackelberg game.
    DOI: 10.1504/IJOR.2020.10041210
  • Analyzing a queueing network of the emergency department with deteriorating health in post-disaster situations   Order a copy of this article
    by Sara Benvidi, Tooba Asghari, Amir Aghsami, Fariborz Jolai 
    Abstract: Providing appropriate healthcare services in emergency departments (ED) after a disaster is a good way to reduce casualties. This study attempts to model an ED as a three-stage queue with a deteriorating patient’s health condition where the system experiences a disaster. Triage has been considered as the primary stage which classifies patients into two types. The paper aims to present the best budget planning and capacity planning to minimise total death and waiting times. Queueing networks are used to model the mentioned situation. Finally, three mathematical formulations are accompanied by numerical experiments. We observed the behaviour of each model to support managers in policy makings. We conclude that exigent plays a significant role in the total death number and service rate of triage and semi-urgent, significantly impacting the total waiting time.
    Keywords: emergency department; healthcare; Markovian queueing systems; budget and capacity planning; triage; deterioration; disaster.
    DOI: 10.1504/IJOR.2021.10041212
  • Lot Sizing Model for multiple products over Finite Planning Horizon under the Effect of Learning and Time-Value of Money with cap-and-trade and carbon tax regulations: A Fuzzy Framework   Order a copy of this article
    by Narendra Kumar, Rachna Kumari, Dharmendra Yadav 
    Abstract: This study presents a multi-item manufacturing process by assuming that the demand for different products depends on the selling price and awareness program. The manufacturer adopts a system improvement program to reduce the defective items and an investment policy on green technology to curb carbon emission. Article also explores the influence of learning on unit production time. Impreciseness in different costs is handled with fuzzy set theory. The optimal solution is obtained with the help of the classical optimisation technique. Further, obtained results indicate the advantage of carbon regulation policies as carbon tax and carbon cap and trade policy. The result also shows a significant improvement in the system's profit by considering the learning effect. Whole of the study is carried out under the impact of inflation. The developed model is investigated further with the help of a numerical example. In the end, sensitivity analysis is performed for important parameters.
    Keywords: multi-items; learning effect; promotional activity; selling price dependent demand; imprecise costs; signed distance method; inflation; finite planning horizon.
    DOI: 10.1504/IJOR.2021.10041538
  • A Simplified Multi-Granular Linguistic Term Sets Method   Order a copy of this article
    by Harliza Mohd Hanif, Daud Mohamad, Rosma Mohd Dom 
    Abstract: The multi-granular concept involves many parts of a complex system or model. Since the late 1990s, many researchers have started to incorporate multi-granular concepts in their research areas. This paper focuses on the use of multi-granular linguistic (MGL) term sets in the decision-making method. The use of the MGL method in decision-making may impose a high level of complexity since it offers flexibility to the decision maker. The flexibility given is by determining the output of the cardinality. Complexity in a method may impose disadvantages in terms of, for example, inaccuracy of outcomes, loss of information, and time consumption. Hence, a simplified multi-granular linguistic term sets (SMM) method is proposed with a lower complexity level to overcome the disadvantages of complexity. This was achieved by introducing a parallel process of cardinality (PPC) into the simplified multi-granular linguistic term sets method (SMM). After proposing the simplified multi-granular linguistic term sets method, the complexity level of this method is compared with other methods based on the relative complexity index (RCI).
    Keywords: cardinality; multi-granular; parallel-process; simplified.
    DOI: 10.1504/IJOR.2021.10041842
  • A new model for physician assignment based on fuzzy rules extraction from climatic factors   Order a copy of this article
    by Sima Hadadian, Zahra Naji Azimi, Nasser Motahari Farimani, Behrouz Minaei-Bidgoli 
    Abstract: The number of patients should be predicted to meet the physicians demands in hospitals. In this study, a new multi-objective physician assignment model was designed based on the number of the patients estimated by the climatic factors. The number of patients was predicted through multiple linear regression (MLR) and fuzzy inference system (FIS). In the FIS, the feature selection was performed by the genetic-K-nearest neighbours algorithm. Then, fuzzy rules were extracted using fuzzy associative classification. After predicting the number of patients, the physician assignment model was designed. The case study is a paediatric hospital with four wards. The results indicated some medical fuzzy rules based on climatic factors. In addition, RMSE and MAE, as compared with MLR in all hospital wards, had a lower value in the FIS. Finally, the advantage of the assignment model could be attributed to its sensitivity to changes in the number of the patients.
    Keywords: multi-objective model; physician assignment; fuzzy associative classification; FAC; fuzzy inference system; FIS; genetic-K-nearest neighbours algorithm; multiple linear regression; MLR.
    DOI: 10.1504/IJOR.2021.10041843
  • An Inventory System Using Preservation Technology Investment for Ameliorating and Deteriorating Items with Ramp-Type Demand Dependent on Price and Time and Partial Backlogging   Order a copy of this article
    by AJOY HATIBARUAH, Sumit Saha 
    Abstract: This article describes an inventory model developed for ameliorating items considering ramp type demand dependent on price and time with partially backlogged shortages. Ameliorating items such as livestock are raised in the farm when their size and quantity are small. The quantity and size of these items increase due to their high growth rate. However, their quantity may decrease due to certain diseases or death. Amelioration rate is described by Weibull distribution. Preservation technology is adopted to reduce the deterioration effect. Ramp type demand results in two possible cases, for which two different models were developed. Our goal is to estimate optimal preservation technology cost, selling price and the time at which maximum inventory and shortage occurs while total cost is minimised. Some numerical examples for two different cases are solved. Impact of the parameters on optimal solution is analysed through sensitivity analysis while the results obtained are discussed accordingly.
    Keywords: inventory; amelioration; deterioration; price and ramp-type time dependent demand; preservation technology investment; partial backlogging.
    DOI: 10.1504/IJOR.2021.10041900
  • A technique to solve mixed strategy non-cooperative zero sum games with more than two players   Order a copy of this article
    by RANJAN GUPTA, Debdip Khan 
    Abstract: In this paper, we have proposed a technique, capable of solving m
    Keywords: game theory; N-persons mixed strategy game; two-dimensional representation; two persons zero sum game; genetic algorithm.
    DOI: 10.1504/IJOR.2021.10041969
  • Restructuring of units under inter-temporal dependence: Method and application   Order a copy of this article
    by Mona Avand, Seaid Ghobadi 
    Abstract: This paper deals with the generalised restructuring decision making units under inter-temporal dependence data. An important issue for generalised restructuring of a set of decision making units is the estimation of the input and output levels inherited from pre-restructuring decision making units between post-restructuring decision making units to achieve full dynamically efficiency levels. This issue, the input and output-estimation for achieving efficiency targets, is investigated via the inverse data envelopment analysis concept. An effective method is provided that allows managers to incorporate their preference in targets setting of a restructuring for saving/producing specific input/output levels in each time period of the assessment window as much as possible. Sufficient conditions are derived for input and output estimation using multiple-objective programming problems. The applicability of the proposed method is illustrated through a banking sector example.
    Keywords: data envelopment analysis; DEA; inverse DEA; generalised restructuring; inter-temporal dependence; multiple-objective programming; MOP.
    DOI: 10.1504/IJOR.2021.10042139
  • Two-Commodity Multi-Server Queueing-Inventory System with Compliment Product and Classical Retrial Facility   Order a copy of this article
    by Jeganathan Kathirvel, Nithya M, C. SUGAPRIYA, Selvakumar Subramanian 
    Abstract: This article explores a two-commodity stochastic queueing-inventory system (TCSQIS) along with a multi-server and a classical retrial facility. In this two-commodity, the first one is called a primary product (PP) and the second one is called a complimentary product (CP). The TCSQIS provides a multi-server service facility to an arriving customer in order to reduce the loss of arrival and increase more sales and profit. Suppose the arriving customer sees that all the servers are engaged or there are no sufficient products in the system, they go to an infinite orbit compulsorily. The customers in orbit can approach the system under classical retrial policy, whenever they confirm that the system must consist of at least one server that is free and positive stock. The stationary probability vector is obtained by the matix-geometric approach (MGA). Further, adequate examples are provided to explore the proposed model.
    Keywords: multi-server; compliment product; infinite orbit; classical retrial policy; waiting time.
    DOI: 10.1504/IJOR.2021.10042182
  • Advanced Payment Strategy for EOQ Model regarding Perishable Product With Maximum Lifetime,Customer Return, Preservation Technology and Partial backlogging   Order a copy of this article
    by Ravendra Kumar, Ravish Kumar Yadav 
    Abstract: Many products, like fruits, vegetables, etc. have a certain life that depends on the preserving conditions and also the demand of these products depends on their life. Selling price and the investment in a preservation mechanism are the most important factors in inventory management. An economic order quantity model is proposed focusing on perishable products having a certain lifetime. A preservation mechanism has been implemented to extend the products lifetime. Two different models with or without shortages are presented here. Concavity of objective function is established using several theorems. Developed model is validated with the help of numerical examples. Sensitivity is also carried out. The results show that the retailers profit reduces when dealing with products for which customers are more concerned about the products lifetime. The findings also suggest that in order to increase profit, retailers should design an inventory policy that controls purchase costs and interest.
    Keywords: advanced payment; EOQ; perishable product; customer return; preservation technology; partial backlogging.
    DOI: 10.1504/IJOR.2021.10042219
  • Investigation of Production Systems for two-level Supply planning with Breakdown and Lead Times Uncertainties   Order a copy of this article
    by Parimah Zandi, Heibatolah Sadeghi, Hiwa Farughi 
    Abstract: This paper investigates the supply planning of two-level and multi-period inventory control with stochastic lead time and random machine breakdown. Due to the probability of lead time, the actual lead time may be longer than the planned time in each production cycle, which will delay the delivery of the final product to the final customer, and it is also possible that the final product will be ready to be delivered to the customer sooner than the specified time, in which case the product is maintained and delivered to the customer at the specified time, which imposes additional maintenance cost on the production system. Also, due to the random machine breakdown, the machine may break during production or outside the production cycle. Demand for the final product and the policy of supplying demand is considered as periodic order quantity. The purpose of the problem is to determine the planned lead time and time interval between production orders based on periodic order quantity policy and uses the genetic algorithm to minimise the total system costs. Finally, a numerical example is explained, based on which the main parameters of the proposed model are analysed.
    Keywords: planned lead time; stochastic lead time; order quantity policy; maintenance.
    DOI: 10.1504/IJOR.2021.10042232
  • Credit rating ranking of Iranian Banks based on CAMELS and Hybrid Multi-Criteria Decision Analysis methods in uncertain environment   Order a copy of this article
    by Amir Karbassi Yazdi, Precious Okereke, Peter F. Wanke, Seyed Arash ShahrAeini, Amir MehdiAbadi 
    Abstract: This research aims to rank Iranian banks by CAMELS and multi-criteria decision analysis (MCDA) methods in uncertain environments. Ranking banks can lead to a better understanding of how customers select them and use their services. Since there is close competition between private and government banks in Iran, the most popular rating system (CAMELS) can help customers gain a better understanding of their situation. The CAMELS method consists of a rating based on bank performance factors. For finding the best bank in Iran once the CAMELS factors are considered, banks are then ranked by the COmbined COmpromise SOlution (CoCoSo) method, which also requires the stepwise weight assessment ratio analysis (SWARA) method to be used. The environment, however, is changing, thus affecting decision makers (DMs), so using uncertainty methods such as Pythagorean fuzzy numbers (PFN) is essential, which helps DMs make better decisions. The sample population of this research is eight public banks in Iran. The result indicates the best bank based on CAMELS and MCDA methods in uncertain environments with the result also pointing out how banks with a lower performance can do benchmarking to improve their performances according to CAMELS factors.
    Keywords: CoCoSo method; SWARA; CAMELS method; bank credit rating; Pythagorean fuzzy numbers; PFN.
    DOI: 10.1504/IJOR.2021.10042454
  • Analysis of MAP/PH(1), PH(2), PH(3)/1 Queueing System with Two Modes of Heterogeneous Service, Standby Server, Vacation, Impatient Behavior of Customers, Additional Service, Startup Time, Breakdown and Phase Type Repairs   Order a copy of this article
    by AYYAPPAN Govindan, Thilagavathy Karthikeyan 
    Abstract: In this article, we consider a single server queue in which customers arrive according to the Markovian arrival process (MAP) and their corresponding two modes of service based on phase-type (PH) distribution. While the main server is offering either two modes of service or additional service, the server may affect by breakdown immediately go for the repair process. At that moment, the service process switches over to the standby server until the main server rejuvenated from the phase-type repair. When vacation completion epoch, the main server will do the startup process. Using the Matrix-Analytic method, we investigated the total number of customers in the system under the steady-state probability vector. We examined the stability condition, busy period and characteristics of some performance measures of the system are discussed. Numerical results are tabulated and graphical representations are provided for a clear view of our model.
    Keywords: Phase-Type Distribution; Markovian Arrival Process; Standby Server; Impatient Behavior; Additional service.
    DOI: 10.1504/IJOR.2021.10042582
  • Multi-Objective Faculty Course Timeslot Assignment Problem for Tutorial and Laboratory Courses   Order a copy of this article
    by Sunil Bhoi, Jayesh Dhodiya 
    Abstract: This study applied a multi-objective zero-one integer programming model to resolve the university timetabling problem of assigning timeslots to faculty member for tutorial and laboratory courses. The model helps prepare an efficient and effective timetable by optimising the satisfaction levels of faculty members, administrators, and students. It ensures that no conflict occurs between tutorial and laboratory courses and their proper distribution across days and sessions. Furthermore, the model assigns all batches of the same course to one faculty member to save preparation/laboratory setup time. Appropriate scheduling allows each batch to utilise their time for self-study courses, library, and extracurricular activities. The model systematically incorporates two-hour laboratory courses in two consecutive break-free timeslots and the proper utilisation of the library and preparation for self-study courses by students. The model was applied to a technical institute using hypothetical data, and effectual and feasible schedules were generated using fuzzy programming. The solutions were obtained using LINGO 18.0 software.
    Keywords: timetabling; university course scheduling; multi-objective programming; zero-one linear programming; fuzzy programming technique.
    DOI: 10.1504/IJOR.2021.10046716
  • A novel inverse DEA model for restructuring DMUs with negative data   Order a copy of this article
    by Seaid Ghobadi, Khosro Soleimani, Ehsan Zanboori 
    Abstract: One of the important issues in generalised restructuring of a set of units is the identification of the input and output levels from a new set of post-restructuring units. This paper deals with the generalised restructuring of decision making units (DMUs) in the presence of negative data for achieving efficiency targets. A novel inverse DEA model is proposed for modelling the generalised restructuring of a set of DMUs in the presence of negative data. Sufficient conditions are given for estimation of inputs and outputs of the new set of post-restructuring units to realise efficiency targets. A numerical example is employed to illustrate the developed theory.
    Keywords: data envelopment analysis; DEA; inverse DEA; multiple objective programming; MOP; generalised restructuring; efficiency; negative data.
    DOI: 10.1504/IJOR.2020.10042860
  • Pascal’s Triangle Graded Mean Defuzzification Approach For Solving Fuzzy Assignment Models by Using Pentagonal Fuzzy Numbers   Order a copy of this article
    by Zeina Mohammed  
    Abstract: The fuzzy assignment models (FAMs) have been explored by various literature to access classical values, which are more precise in our real-life accomplishment. The novelty of this paper contributed positively to a unique application of pentagonal fuzzy numbers for the evaluation of FAMs. The new method namely Pascal’s triangle graded mean (PT-GM) has presented a new algorithm in accessing the critical path to solve the assignment problems (AP) based on the fuzzy objective function of minimising total cost. The results obtained have been compared to the existing methods such as, the centroid formula (CF) and centroid formula integration (CFI). It has been demonstrated that operational efficiency of this conducted method is exquisitely developing an optimal solution (Opt. Sol.) depending on the corresponding path by the new tender algorithm.
    Keywords: centroid formula; centroid formula integration; CFI; fuzzy assignment models; FAMs; optimal solution; Opt. Sol.
    DOI: 10.1504/IJOR.2021.10042897
  • Pricing and Ordering Strategy for New Product and Buyback Strategy for Used Product from Retailer’s Point   Order a copy of this article
    by DHARMESH KATARIYA, Kunal Shukla 
    Abstract: Today environmental spectrums are much considered while purchasing a new product because of global awareness about sustainability of environment, hence an interest for use of restored products has increased. The retailer is a decision-maker; retailer sells a new product to the consumers and also collects the used sold products for reselling. In this deteriorating inventory model, the demand rate of new products is a nonlinear function and demand rate of used buyback products is linear function of selling price and time-dependent respectively. Shortages are allowed and the unsatisfied demand is partially backlogged. The objective is to maximise total profit per time unit for a retailer concerning to optimise selling price, order quantity for a new product, and quantity of used buyback products simultaneously. Global optimality is verified by Hessian matrix method and graphically. This model is explained through a numerical example, sensitivity analysis, and managerial insights. Ultimately, some concluding remarks with future scopes are discussed.
    Keywords: inventory; used buyback product; price dependent demand; deterioration; partial backlogging.
    DOI: 10.1504/IJOR.2021.10042898
  • An Adaptive Large Neighborhood Search Algorithm for Blocking Flowshop Scheduling Problem with Sequence-Dependent Setup Times   Order a copy of this article
    by Faezeh Bagheri, Morteza Kazemi, Ardavan Asef-Vaziri, Mahsa Mahdavisharif 
    Abstract: Flowshop scheduling problem (FSP) belongs to the classical combinatorial optimisation problem and takes different forms under different production conditions. To make the general form of FSP closer to the real production environment, two assumptions, including blocking and sequence-dependent setup time, were added. The first attempt of the current research work is proposing a mathematical model according to two different viewpoints about blocking occurrence affected by sequence-dependent setup time that try to use the dead time (blocking or idle time) for setting-up the next job. Due to the complex intrinsic of combinatorial problems, achieving the exact result on a large-scale through a mathematical model is almost complicated. The second attempt is developing an adaptive large neighbourhood search algorithm to solve the problem on a large-scale which is accelerated by a new constructive heuristic algorithm. Extensive computational experiments on various size problems support the efficiency of the proposed algorithms.
    Keywords: flowshop; blocking; sequence-dependent setup time; heuristics algorithm; adaptive large neighbourhood search algorithm; mathematical modelling.
    DOI: 10.1504/IJOR.2021.10042973
  • Impact of Waste Management and Regulatory Mechanism on Sustainable EOQ Model with Controllable Non-Instantaneous Deterioration and Trade Credit-and Carbon-Sensitive Demand   Order a copy of this article
    by Sharad Kumar, Seema Agarwal, Dharmendra Yadav 
    Abstract: Non-instantaneous deterioration, trade credit, waste management, carbon sensitive demand, and preservation technology all have a significant impact on inventory control policies. So, taking into cognisance of these issues, an economic order quantity model has been developed to minimise the total inventory cost by considering the preservation technology (PT) to mitigate the rate of deterioration and to increase the length of the non-deterioration period. The objective of achieving financial sustainability is accomplished by taking into account the trade credit period. Consumers are becoming more environmentally conscious. As a result, it is assumed that demand rate is a function of the trade credit period and carbon level. Shortages are allowed with partially backlogging at a constant rate. To reduce carbon emissions, two different mechanisms, namely carbon tax and carbon cap-and-trade, are used. A solution algorithm is developed to obtain an optimal solution. The findings revealed that total inventory costs are reduced efficiently due to preservation technology and trade credit. According to the findings, environmentally friendly decision-makers preferred a carbon tax mechanism over a carbon cap-and-trade system. Analysis also suggested that the trade credit period has a positive impact on the total inventory cost.
    Keywords: waste management; trade credit; carbon tax; carbon cap-and-trade; partial backlogging.
    DOI: 10.1504/IJOR.2021.10043154
  • Three Rates of Production Inventory Models for Deteriorating Items with Constant, Linear and Quadratic Demand   Order a copy of this article
    by Sivashankari C.K., Valarmathi R. 
    Abstract: Three-rates of production inventory models with constant, linear and quadratic demand for deteriorative items are considered in this study. The demand models found in the literature include constant, linear, quadratic, exponential, price dependent and stock dependent among others. To wit, no study exists that uses three-rates of production inventory models with constant, linear and quadratic demands. The first model uses three-rates of production inventory model with constant demand rate for deteriorative items, the second model uses three-rates of production inventory model with linear demand for deteriorative item, and the third model uses three-rates of production inventory model with quadratic demand for deteriorative item. Mathematical models are delineated for each model and relevant examples are provided to elucidate the proposed procedure. The objective herein is to obtain optimum order quantities and order intervals concerning the overall cost. Sensitivity analysis is provided for each of the three models. The necessary data was generated using Visual Basic 6.0. Three models are developed: the variation in production rate provides a way resulting consumer’s gratification and earning potential profit.
    Keywords: constant; linear and quadratic demands; three-rates of productions; optimality; comparative study.
    DOI: 10.1504/IJOR.2021.10043155
  • Scheduling with team production effects   Order a copy of this article
    by Tobias Wiens, Christian A. Ullrich 
    Abstract: This paper introduces the new research field of team assignment and scheduling, while taking into account the team production effect. In contrast to the opinions prevalent in the literature on job-splitting, a given job’s processing time is not simply its default processing time on one machine divided by the number of machines assigned to that job. Synergies may lead to nonlinear relations between the number of assigned machines and the resulting processing times. After combining team production and scheduling theory in general, we focus on two common problem areas: minimising the maximum completion time and minimising the total tardiness. In the face of NP-hardness, we propose a specialised genetic algorithm which is general enough to tackle both problem areas. Computational experiments demonstrate the effectiveness of the approach.
    Keywords: scheduling; team production; parallel machines; genetic algorithm; neighbourhood search.
    DOI: 10.1504/IJOR.2021.10043215
  • Optimization, Planning and Mutualization of Chicken Production in a Multi-Supplier, Multi-Period, and Multi-Horizon Poultry Network: Case Study   Order a copy of this article
    by Tahraoui Nacéra, Lamia Triqui-Sari, Mohammed BENNEKROUF 
    Abstract: This study addresses the planning issue related to the broilers production in a poultry network. where the major problem is the imbalance between the supply and the demand. To this fact, the produced quantity is unstable, which influences selling prices. To effectively solve this problem, we have developed a generic linear programming model in order to facilitate the decision-making in production. The formulation is motivated by a real application case of the poultry chain in the city of Tlemcen. In this context, several configurations were tested: an economic configuration determined by financial planning, and a mutual configuration promoting the service quality. Also, we have developed a mathematical model for an integrated multi-horizon approach to organise the production rotation of all breeding farms over the long-term. Promising results have increased the breeder’s profit, and the service quality where all actors, breeders as well as consumers, will be in a win-win situation.
    Keywords: production planning; broilers chicken; linear programming; cooperative planning; integrated multi-horizon optimisation; case study.
    DOI: 10.1504/IJOR.2021.10043657
  • Analysis on multi service interruption in the Queuing system   Order a copy of this article
    by S. Maragathasundari, P. Manikandan 
    Abstract: This article is about a queuing system in which the server is interrupted twice and then the repair process is carried out immediately without delay. After the service ends, if there is no client in the system, the server can choose to take a Bernoulli vacation. In addition, consequent occurrence of interruption of the system is an inevitable feature in our daily life activities. Also, during the repair process of second type interruption, process of Reneging happens. The queuing issue is drawn closer through supplementary variable technique of queuing hypothesis and the comparing framework likelihood producing capacity of the line length and the various queue measures are determined. Also, the queuing model is well explained by means of real-life application and processed by the way of numerical structure and graphic representation. This model means making a supervisor aware of the structural difficulties of a client-server-based framework and recognising the basic rules of investigation.
    Keywords: web server; reneging; service interruption; repair process.
    DOI: 10.1504/IJOR.2021.10043989
  • Expectation and Fractile Models for Decentralized Distribution Systems under Demand Uncertainty and their Computational Methods   Order a copy of this article
    by Ichiro Nishizaki, Tomohiro Hayashida, Shinya Sekizaki, Naomichi Tani 
    Abstract: In this study, we deal with the expectation and the fractile models for obtaining a Nash equilibrium point of the two-stage game for describing the competition and cooperation in decentralised distribution systems with stochastic demands, and develop computational methods. In the first stage of the equilibrium problem, each retailer independently determines the inventory level, and in the second stage for the coordination of retailers, the addition profit arising from the transshipment of the leftover inventories of all the retailers is maximised. Formulating the transshipment of the leftover inventories as a two-stage programming problem with simple recourse, we define an allocation rule based on the optimal dual solution of the transshipment problem which belongs to the core of the cooperative game. Using numerical examples, we demonstrate the effectiveness of the expectation and the fractile models, and examine the validity of their computational methods.
    Keywords: decentralised distribution systems; equilibrium points; expectation and fractile models; two-stage games; computational methods.
    DOI: 10.1504/IJOR.2021.10044002
  • Arbitrage Opportunity Estimation: The Case of the Cobb-Douglas Production Function   Order a copy of this article
    by Sergey Anokhin, Maxim Bushuev, Elena Akerman, Vladislav Spitsin, Dmitry Anokhin 
    Abstract: The entrepreneurship literature has recently become aware of the phenomenal promise of efficiency evaluation techniques for gauging one of its key concepts arbitrage opportunities. Unfortunately, the use of DEA, the dominant efficiency evaluation approach, for this purpose is limited by some of the properties of the method. In this paper we develop an alternative method that could be used to assess opportunities for imitation (arbitrage) available to entrepreneurial firms. We adapt the minimum performance inefficiency technique to the Cobb-Douglas production function, compare the new method to the dominant efficiency estimation techniques that could be used to measure arbitrage opportunity, and run a Monte-Carlo experiment to explore its applicability to alternative types of production functions typically tackled with data envelopment analysis. We show that the new method may provide more accurate results than the mainstream approaches, and demonstrate a real-life application of the technique in the publishing industry setting.
    Keywords: data envelopment analysis; DEA; minimum performance inefficiency; MPI; entrepreneurship; arbitrage opportunities; Cobb-Douglas.
    DOI: 10.1504/IJOR.2021.10044099
  • An Advanced Fuzzy Approach for Assessing Supply Chain Resilience in Developing Economies   Order a copy of this article
    by Saleh Fahed Alkhatib  
    Abstract: This paper aims to develop an advanced fuzzy approach to assess the supply chain resilience (SCRE) in the developing economies under high uncertainty. The new approach incorporates the fuzzy decision-making trial and evaluation laboratory (FDEMATEL), the modified fuzzy best worst method (FBWM), and fuzzy techniques to order preferences by similarity to ideal solution (FTOPSIS) in a novel way to employ their merits. A systematic literature review of the SCRE dimensions was conducted to identify main SCRE factors. The FDEMATEL method obtained the relationships among these dimensions to provide a better understanding of this system. The FBWM weights these dimensions and identify their relative importance, and finally, the SCRE level was evaluated by the FTOPSIS method. A real case of the leading non-financial companies in the Middle East and North Africa (MENA) region were investigated. The research results revel several findings that provide useful insight for the MENA companies and academia.
    Keywords: supply chain resilience; SCRE; MENA region; fuzzy set theory; FDEMATEL; fuzzy best worst method; FBWM; FTOPSIS.
    DOI: 10.1504/IJOR.2021.10044173
  • Examination and Class Timetabling Problem: A Case Study of an Indian University   Order a copy of this article
    by A.K. Agrawal, Susheel Yadav, Amit Ambar Gupta, Shubhendu Pandey 
    Abstract: Timetabling problem is basically an optimisation problem and is a subset of scheduling problems. A timetabling problem is a problem where events (classes, examination and student) have to be ordered in time slots while satisfying some basic constraints. Here the basic aim is to satisfy various constraints, such as, no student can be scheduled for more than one course at the same time and the maximum number of students that can be scheduled to any particular class must not exceed the sitting capacity of the class. So the timetabling problem is basically arranging the given set of values (class, subject and students) in such a manner such that the resulting schedule should fulfil all the above stated hard constraints and try to give more close values near to the soft constraints (such as proper distribution of classes over available slots). In the present work, examination timetable and class timetable problems have been considered with several practical features. The problems are formulated as mathematical models and heuristic approach is also proposed to solve them. The heuristic uses the basic framework of genetic algorithm.
    Keywords: timetabling; soft constraints; heuristics; genetic algorithm; mathematical modelling.
    DOI: 10.1504/IJOR.2021.10044175
  • On Modeling and Lot Sizing of the Newsvendor Problem with Surrogate Product   Order a copy of this article
    by Layek Abdel-Malek, Pinyuan Shan, Roberto Montanari 
    Abstract: There is a growing interest in the newsvendor problem and its extensions. One of these extensions is in the area of product substitution. In this work, we model the situation where two perishable products are considered, a primary product and a surrogate one. The primary product yields higher profit than the surrogate. The objective of the model is to find the optimal lot sizes of both products that minimise the total ordering cost (alternatively, maximise the profit). Numerical analysis and examples to show the contribution of the surrogate approach to the overall performance of the policy are presented as well as some managerial insights. The applications of this model can occur in retail of perishable commodities, fashion sector, and products of high rates of technological obsolescence as well as service industries such as hotel reservation and car rentals.
    Keywords: newsvendor problem; stochastic optimisation; supply chain management; product substitute; decision making.
    DOI: 10.1504/IJOR.2021.10044176
  • Pythagorean Fuzzy Goal Programming: A Novel Approach and its Application   Order a copy of this article
    by Sayan Deb, Sahidul Islam 
    Abstract: The present study discusses a novel goal programming technique for solving multi-objective problems. The technique is named Pythagorean fuzzy goal programming. The improved score function of the Pythagorean fuzzy sets has been used to develop the technique. Goal programming (GP) techniques have been proven to be very useful in the field of operations research. GP techniques are used to find the best compromise solutions for a multi-objective programming problem. An example of a supplier selection model is provided where the traditional intuitionistic fuzzy GP technique fails to optimise but the proposed technique provides an optimal solution. This technique is useful for the systems where the other GP techniques fail to provide any results.
    Keywords: Pythagorean fuzzy goal programming; goal programming; Pythagorean fuzzy sets; supplier selection model.
    DOI: 10.1504/IJOR.2021.10044247
  • A Fuzzy Logic Approach for Housing Affordability Level Analysis   Order a copy of this article
    by Nerda Zura Zaibidi, Adyda Ibrahim, Nor Syuhaddah Saiddin 
    Abstract: The issue of house prices are either too high or unaffordable is widely discussed. The price index indicates residential units’ prices continue to climb from one year to another. Consequently, the number of unsold residential units becomes high. This issue has raised concern among researchers to analyse about the affordability level among house buyers. This study aims to measure the affordability level of house buyers in Malaysia by using a fuzzy logic approach. Two inputs are being considered; house price ranges and household incomes while for the output is the affordability level. The findings show that the affordability level for the middle-income earners in Malaysia is low. This finding can help the authorised body to look carefully into this issue and find a strategic solution to overcome the problems to avoid the housing development turning into a slump.
    Keywords: fuzzy logic; house prices; housing affordability; housing market.
    DOI: 10.1504/IJOR.2021.10044471
  • Addressing Stock Market Time Series Trends and Volatility Using Optimized DE-LSTM Model   Order a copy of this article
    by Raghavendra Kumar, Pardeep Kumar, Yugal Kumar 
    Abstract: Accurate time series prediction is a most challenging trend before research communities in the machine learning era. Stock market data is the most dynamic and volatile time series data that holds the world economy. Recent studies proposed various core and hybrid machine learning models to get accurate stock forecasting. Existing work put forward long short-term memory (LSTM) to implement sequential time series data. In this paper, a new nonlinear hybrid model is proposed using customised LSTM and differential evolution (DE) algorithms. DE brings the optimisation of selection of parameters and provides stability between complexity and learning performance of the hybrid model. The paper explores the forecasting accuracy of the stock market trends and volatility using hybrid model DE-LSTM. The proposed hybrid model obtained significant improvement as MAE, RMSE and MAPE are 0.21167, 2.48198 and 2.68331 respectively, practiced for a diversified portfolio of Bombay Stock Exchange, India (BSE30).
    Keywords: stock market trends; volatility; time series data; long short-term memory; LSTM; differential evolution; DE.
    DOI: 10.1504/IJOR.2021.10044472
  • A tabu search heuristic for the outsourcing risk management problem in multi-echelon supply chains   Order a copy of this article
    by Arian Nahangi, Mohamed Awwad 
    Abstract: Globalisation has made supply chains more vulnerable to risk factors, increasing the associated costs of outsourcing goods. This paper considers a multi-echelon supply chain model with global and domestic raw material suppliers, manufacturing plants, warehouses, and markets. The problem is formulated as a mixed-integer linear programming model. Due to the NP-hard nature of the problem, a tabu search heuristic is proposed to solve small, medium, and large problem instances. A quadratic multi-regression analysis is used to analyse the performance of the proposed tabu search heuristic. The statistical analysis shows that increasing the number of iterations and neighbours will increase run time and reduce total supply chain cost. The proposed tabu search heuristic proved to provide an efficient solution, including large problem instances, in a timely manner.
    Keywords: multi-echelon supply chain; risk management; outsourcing; tabu search; multi-regression.
    DOI: 10.1504/IJOR.2021.10044473
  • Integrated Bioethanol-Gasoline Supply Chains (IBGSCs) created in response to government policy changes in Nebraska   Order a copy of this article
    by Davoud Ghahremanlou, Wieslaw Kubiak 
    Abstract: The US Government applied its policy-making power to mitigate the negative impact of COVID-19 on integrated bioethanol-gasoline supply chains (IBGSCs). In order to study the IBGSCs which evolve in response to change of policies, Ghahremanlou and Kubiak (2021) developed an algorithm, referred to as extended lean model (ELM). In this paper, we apply the ELM to real-life data for the State of Nebraska and solve 21,420 alternative policy scenarios to optimality to investigate and compare IBGSCs created due to the changes in policies. The case study shows that minimum tariffs for blending US and non-US bioethanol with gasoline needs to be 0.531 and 0.35 $ gal respectively to permit the government to shift bioethanol production in order to meet demand for ethanol used for producing sanitisers to avert COVID-19 from spreading. Finally, we provide a number of policy recommendations and directions for further research.
    Keywords: COVID-19; oil war; supply chain management; operations management; stochastic programming; location allocation; government policies; sustainability.
    DOI: 10.1504/IJOR.2021.10044574
  • Operational Research Application to Minimize the Uncertainty of Time and Cost in the Main Domains of Industrial Engineering by Using Quality Engineering Techniques   Order a copy of this article
    by Ramin Rostamkhani, Mohammad Hossein Karimi Gavareshki, Morteza Abbasi, Mahdi Karbasian 
    Abstract: The present research attempts to introduce an operational research model to minimise the uncertainty of time and cost in the main domains of industrial engineering (IE) by using quality engineering techniques (QET). The research approach is based on three processes. The first process reviews QET among the most important IEF. The second process relates to the influential factors. The third process concentrates on the operational research model by applying the fuzzy multi-objective linear programming. A numerical application for the third process is explained. The assessment results are endorsed by the management representatives’ views in the organisation. The first innovative aspect of the research is the combination of QET and IE in the operational research model to save time and cost within the organisation. The second novelty of the current study is the use of quantum mechanics perspectives for the time concept in the long-term.
    Keywords: uncertainty; industrial engineering; quality engineering techniques; QET; multi-objective linear programming.
    DOI: 10.1504/IJOR.2021.10044581
  • An Efficient Merge Search Matheuristic for Maximising Net Present Value in Project Scheduling   Order a copy of this article
    by Dhananjay Thiruvady, Su Nguyen, Christian Blum, Andreas Ernst 
    Abstract: Resource constrained project scheduling (RCPS) is an important combinatorial optimisation problem with many practical applications. With complex requirements such as precedence constraints, limited resources, and finance-based objectives, finding optimal solutions for large problem instances is very challenging. To address this challenge, we propose a new matheuristic algorithm based on merge search and parallel computing to solve RCPS with the aim of maximising the net present value. This paper presents merge search, a novel matheuristic designed for RCPS, which is a variable partitioning and merging mechanism to formulate restricted integer programs. Parallel ant colony optimisation can generate excellent solutions for RCPS, and we use this method to generate the solution pool. The experimental results show that the proposed method outperforms the current state-of-the-art algorithms on known benchmark problem instances. Further analyses also demonstrate that the proposed algorithm is substantially more efficient compared to its counterparts in respect to its convergence properties.
    Keywords: project scheduling; net present value; NPV; merge search; construct; merge; solve and adapt; CMSA; parallel ant colony optimisation.
    DOI: 10.1504/IJOR.2021.10044652
  • Efficient mixed-integer linear programming formulations for the satellite broadcast scheduling problem   Order a copy of this article
    by Ananthu Krishna S, GIRISH B. S, Devendra Prakash Ghate 
    Abstract: Satellite broadcast scheduling problem (SBSP) is an important optimisation problem in satellite communication systems and is known to be NP-complete. The existing state-of-the-art solution methodologies for the SBSP include neural networks, evolutionary algorithms, and other heuristic approaches. This paper proposes two new mixed-integer linear programming (MILP) formulations for the problem. The performance of the proposed MILP formulations has been evaluated using benchmark problem instances and several other test instances on a commercial MILP solver. Computational results show that the proposed formulations outperform the existing approaches in terms of solution accuracy and computation time.
    Keywords: satellite communications; satellite broadcast scheduling; NP-complete problem; mixed-integer linear programming.
    DOI: 10.1504/IJOR.2021.10044724
  • Technical note: A closed form solution to the k-centra location problem   Order a copy of this article
    by Trevor Hale, Crystal Welker, Ryan Pepper, Faizul Huq 
    Abstract: This research delineates a new heuristic that solves the k-centra location problem on a simple distribution network. This treatise differs from most location research in that we employ a novel, graph theoretic based k-centra approach that seeks to find the location that minimises the sum of the distances to the k furthest existing facilities. The k-centra problem generalises the classic minimax and minisum location problems: If k = 2, the problem reduces to the centre (minimax) location problem, whereas if k = n, the problem reduces to the median (minisum) location problem. This research has direct application to the location of a distribution centre on a simple origin-to-destination distribution network to improve service levels.
    Keywords: facility location; k-centra location; distribution network.
    DOI: 10.1504/IJOR.2021.10044729
  • An Improved Clustering Heuristic in Cellular Manufacturing Systems   Order a copy of this article
    by Arindam Majumder, Dipak Laha 
    Abstract: This paper presents a construction heuristic in cellular manufacturing systems with the objective of maximising grouping efficacy. The proposed method is derived from three criteria, namely, Pearson correlation coefficient, the concentration of operations for a particular machine cell pair or a part family pair, and the density of operations for a particular machine-part cell comprising a machine cell and a part family. The proposed method consists of two phases. In the first phase, the machine-groups and part-families are constructed using Pearson correlation coefficient clustering technique. The second phase involves in selecting the machine-groups and part-families to build the respective machine-part cells to cluster machines and parts into the corresponding machine-groups and part families for the cellular manufacturing problem. The exhaustive computational results based on a set of different benchmark problem instances demonstrate that the proposed method is relatively superior to some well-known state-of-the-art methods.
    Keywords: cellular manufacturing; group technology; grouping efficacy; construction heuristic; correlation coefficient; concentration of operations; density of operations; optimisation.
    DOI: 10.1504/IJOR.2021.10044762
  • Improving Passenger Satisfaction at Kuwait International Airport by using Multi Objective Optimization   Order a copy of this article
    by Ahmad Al-Sultan, Ahmad Alsaber 
    Abstract: Efforts to optimise the quality of services that passengers experience during the check-in process at major airport terminals are important discriminators in deciding the overall quality of the airports themselves. Improvement of passenger services during check-in involves reduction in queues and waiting times. This however, may require additional expansion projects to be undertaken by the authority. Nevertheless, such expansion projects involve conflicting ideas from multiple interest groups due to the absence of any existing efficient simulation model. This paper presents a multi-dimensional approach towards finding an optimal and feasible solution to the resource allocation problem at check-in stages in airports. The proposed methods employ optimisation techniques such as mixed integer goal programming (MIGP) and genetic algorithm (GA) to offer a comparative multi-solution outcome towards optimising the passenger quality of services at airport departure check-in. By adopting the proposed approaches, one can expect to achieve the following objectives: 1) finding an optimum allocation for airlines to different check-in zone area; 2) obtain a feasible planning to undertake decisions concerning check-in area expansion projects reaching their desired goals to improve passenger level of service under limited budget and area space.
    Keywords: airport terminal; integer programming; simulation; mixed integer goal programming; MIGP; Kuwait.
    DOI: 10.1504/IJOR.2021.10044942
  • A new stochastic model in emergency location problem   Order a copy of this article
    by Farshid Esmaeeli Kakhaki, Alireza Pooya, Zahra Naji-azimi, Ahmad Tavakoli 
    Abstract: We propose a new hybrid approach to solve the emergency location problem with stochastic demand. The new method incorporates GIS, system dynamics, Coburn and Spence model, stochastic programming and Monte Carlo simulation. In the proposed method, first, candidate places are extracted using GIS. Since in this paper demand is considered as a stochastic parameter depending on different scenarios of earthquake, in the next step a combination of the system dynamic model and the Coburn and Spence casualty estimation method is used to estimate this parameter. Next, proposing a stochastic location-allocation model, the demand is assigned to candidate places and finally, a Monte Carlo simulation is used to solve the introduced problem. The results of this hybrid model show that if the south fault of Mashhad is activated in the greatest severity, it has the highest possible casualties, in which more than 45 percent of the residents will lose their lives.
    Keywords: Emergency location; Two-stage stochastic programming; System dynamics; Monte Carlo Simulation; Coburn and Spence model; GIS.
    DOI: 10.1504/IJOR.2021.10044952
  • Imperfect EPQ model for substitutable products with pollution costs under uncertain planning horizon   Order a copy of this article
    by Raghu Giri, Shyamal Mondal, Manoranjan Maiti 
    Abstract: The investigation determines optimal pricing decision, greening level, production rate, and cycle length of two substitutable products in an imperfect production process over an uncertain planning horizon, which is taken as random, fuzzy, and rough for maximum profit. Here, products are manufactured and simultaneously defective items are detected during the screening process in the out-of-control state at a random proportion of production rate, which are instantly reworked. The unit production cost is accounted for raw material, labour and energy, greening investment, and wear and tear costs. The carbon emission in the production process due to manufacturing, setup of the production system, and holding of items is considered in the model formulation. Also, introduced the learning effects on the setup and maintenance and operating costs. The profit maximisation problem with some constraints is solved using a genetic algorithm with variable population and realistic suggestions for the managers are presented.
    Keywords: economic production quantity; EPQ; substitute products; imperfect production; cap-and-trade regulation; uncertain planning horizon; learning effects.
    DOI: 10.1504/IJOR.2021.10045057
  • A Multi-Item EOQ Model for Deterioration Items with Ramp-Type Demand and Partial Backlogging under Carbon Emission and Inflationary Environment   Order a copy of this article
    by Vipin Kumar, Anupama Sharma, C.B. Gupta 
    Abstract: Carbon emissions contribute most in the global warming. To minimise the adverse effect of global warming on society, countries are focussing to control CO2 and industries are investing in green products. All of this, inclined the regulatory authorities and customers towards the environment. Thus, present study considers a novel multi-item inventory model for green products. Here, demand rate is considered as a function of initial inventory level, time, and carbon emission. This study also incorporates the carbon emissions associated with different attributes of inventory management such as procurement, purchasing, and holding inventory. Shortages are allowed and depend on the waiting time. The retailer adopts the supplier’s trade credit strategy and study is carried out the inflationary environment. This model aims to optimise the total inventory cost subject to the upper cap of carbon emission. Observation based on analysis indicates some empirical observation. The sensitivity analysis concerning critical parameters showed that the optimal policy for green products is highly sensitive to the costs of shortages, and backlogging. Results indicate that incorporation of carbon issue while modelling for the green products is worthwhile for environment. Around 38% changed is observed in the inventory cost due to the change in scale parameter of demand.
    Keywords: green products; trade credit; partial backlogging; multivariate ramp-type demand; deterioration.
    DOI: 10.1504/IJOR.2021.10045067
  • Multi-Start Constructive Heuristic Through Descriptive Statistical Metrics: The Dhouib-Matrix-4 (DM4) Metaheuristic   Order a copy of this article
    by Souhail Dhouib 
    Abstract: In this paper, we design and develop a new metaheuristic named Dhouib-Matrix-4 (DM4). This method is based on a multi-start structure, where in each start a diversification phase is ensured by a constructive heuristic entitled Dhouib-Matrix-TSP1 (DM-TSP1) and an intensification phase is guaranteed by a novel local search method named far-to-near (FtN). Several descriptive statistical metrics (range, mode, standard deviation, etc.) are used in the heuristic DM-TSP1 in order to explore different realisable solutions. Respectively, these realisable solutions are exploited as starting points by the FtN method using several perturbation techniques (insertion, exchange and 2opt). The performance of the proposed method DM4 is tested on the travelling salesman problem using the well-known TSP-LIB benchmark instances with integer and real distances. Experimental results demonstrate that our approach DM4 is very competitive compared to the last developed metaheuristics.
    Keywords: Operational research; Combinatorial optimization; Travelling Salesman Problem; Optimization; Metaheuristic; Heuristic; Dhouib-Matrix; Computer Science; Artificial Intelligence.
    DOI: 10.1504/IJOR.2021.10045069
  • Optimal Ordering Policies for Stock-dependent Demand under Partial Linked-to-Order Credit Period   Order a copy of this article
    by Nita Shah, Ekta Patel, Kavita Rabari, Hardik Soni 
    Abstract: Trade credit is recognised as an important strategy to increase productivity in inventory management. Hence, an economic order quantity model for stock-dependent demand is proposed under linked-to-order fully and partial delay in payment by considering the practical scenario. The items gradually deteriorate. More precisely, the payment scheme is structured as follows: the order quantity is greater than or equal to a predetermined quantity then full trade credit is offered else partial trade is offered. Shortages are not allowed. The algorithmic procedure to find the optimal replenishment cycle is developed. Finally, managerial insights are drawn to observe the applicability of the proposed model and perform sensitivity analysis on different inventory parameters.
    Keywords: inventory model; trade credit; partial trade credit; linked-to-order trade credit; stock-dependent demand; deterioration.
    DOI: 10.1504/IJOR.2022.10045390
  • Cooperative Advertising Coordination in Two-Level Supply Channel using Differential Game   Order a copy of this article
    by Peter Ezimadu, Jonathan Tsetimi 
    Abstract: There are a lot of models in the cooperative advertising literature, however, only a few have considered channel coordination, and much fewer on the possibility of implementation. This work examines cooperative advertising in a bilateral monopoly using game theory. It considers a two-way coordination strategy in which the manufacturer who is the Stackelberg leader engages in national advertising and provides subsidy for retail advertising, while the retailer who is the follower engages in local advertising and provides motivational advertising support to the manufacturer. The work considers four game scenarios. For each scenario, it determines the players’ optimal advertising efforts and payoffs based on the advertising supports. The work observes that the players’ performances and channel performance are worst with non-provision of support. The retailer performs best with manufacturer’s support, while the manufacturer and the entire channel performances are best with mutual support for each other.
    Keywords: bilateral monopoly; channel coordination; cooperative advertising; co-op advertising; differential game; local advertising; national advertising; Stackelberg game; supply chain; supply channel.
    DOI: 10.1504/IJOR.2022.10045561
  • An optimal integrated inventory management for vendor buyer with substitutable deteriorating product under joint replenishment and cost of substitution   Order a copy of this article
    by Ranu Singh, Vinod Kumar Mishra 
    Abstract: Today’s supply chain network needs a new paradigm shift in the way the buyer and the vendor collaborate. The present article develops an integrated approach for vendor-buyer considering substitutable deteriorating products under joint replenishment. In this study, we consider two mutually substitutable products, and substitution is only taken for the buyer end. In case of one product is out of inventory, the demand for that product can be partially met by the stock of the other product otherwise demand is lost. In the case of substitution, an extra cost of substitution gets involved. The demand, deterioration, and production rate are assumed to be deterministic and constant. The objective of this study is to find the optimal number of deliveries, lot size, production quantity, and stock levels to minimise the integrated entire cost incurred by vendor and buyer. The solution method is suggested to derive the optimal value. A numerical study is provided to show the applicability of the model. Sensitivity analysis and managerial implications are presented to illustrate the validity of the integrated model. The comparative analysis shows that in case of product substitution the effective integrated cost is considerably reduced.
    Keywords: vendor-buyer; optimal policy; deterioration; substitutable product; integrated model; joint replenishment.
    DOI: 10.1504/IJOR.2022.10045692
  • Metaheuristics for Time-Dependent Vehicle Routing Problem with Time Windows   Order a copy of this article
    by Yun-Chia Liang, Vanny Minanda, Aldy Gunawan, Hsiang-Ling Chen 
    Abstract: Vehicle routing problem (VRP), a combinatorial problem, deals with the vehicle’s capacity visiting a particular set of nodes while its variants attempt to fit real-world scenarios. Our study aims to minimise total travelling time, total distance, and the number of vehicles under time-dependent and time windows constraints (TDVRPTW). The harmony search algorithm (HSA) focuses on the harmony memory and pitch adjustment mechanism for new solution construction. Several local search operators and a roulette wheel for the performance improvement were verified via 56 Solomon’s VRP instances by adding a speed matrix. The performance comparison with a genetic algorithm (GA) was completed with the same number of parameters and ran in the same computer specification to justify its performance. The results show that HSA can outperform the GA in some instances. The research outcomes suggest that HSA can solve TDVRPTW with comparable results to other commonly used metaheuristic approaches.
    Keywords: vehicle routing problem; VRP; time window; harmony search algorithm; HSA; genetic algorithm; metaheuristic.
    DOI: 10.1504/IJOR.2022.10045858
  • Marketing Mix Optimisation with Practical Constraints   Order a copy of this article
    by Hsin-Chan Huang, Jiefeng Xu, Alvin Lim 
    Abstract: In this paper, we address a variant of the marketing mix optimisation (MMO) problem which is commonly encountered in many industries, e.g., retail and consumer packaged goods (CPGs) industries. This problem requires the spend for each marketing activity, if adjusted, be changed by a non-negligible degree (minimum change) and also the total number of activities with spend change be limited (maximum number of changes). With these two additional practical requirements, the original resource allocation problem is formulated as a mixed integer nonlinear program (MINLP). Given the size of a realistic problem in the industrial setting, the state-of-the-art integer programming solvers may not be able to solve the problem to optimality in a straightforward way within a reasonable amount of time. Hence, we propose a systematic reformulation to ease the computational burden. Computational tests show significant improvements in the solution process.
    Keywords: marketing mix optimisation; MMO; optimisation; semi-continuous variable; cardinality constraint; perspective reformulation; mixed integer quadratic program; MIQP.
    DOI: 10.1504/IJOR.2021.10045955
  • A note on a two-warehouse partial backlogging inventory model for deteriorating items with permissible delay in payment under inflation
    by Hui-Ling Yang 
    Abstract: In order to satisfy the customer demand, we know that many fashionable product or high-tech electronic items do not allow shortages at the beginning of the replenishment cycle. Furthermore, if the retailer wants to satisfy the demand and increase sales, they do not hope the shortages occur at the beginning of the replenishment cycle. Thus, an alternative inventory model which is different from Yang and Chang (2013) is proposed. The inventory model is assumed shortages are allowed at the end of the replenishment cycle, not at the beginning. The aim is also to derive the retailers optimal replenishment policy that maximises the net present value of the profit per unit time. The theoretical results ensure the optimal solution exists uniquely is presented. Numerical examples and some comprehensive sensitivity analysis are performed. From the numerical results, if the permissible delay period is not long, the proposed model is still practical.
    Keywords: two-warehouse; partial-backlogging; permissible delay in payment; inflation.

  • ABC classification using MCDA, DDF and TOPSIS approach
    by Subhadip Sarkar 
    Abstract: This paper outlines the way of classifying stocking items using multi-criteria decision analysis into A, B and C classes. A combination of directional distance function and technique for order of preference by similarity to ideal solution are suggested in this regard to select the pair of ideal points. The prescribed model argues in favour of designing two frontiers to aid in the categorisation of items with an underlying assumption of convexity. Moreover, the proposed approach has a guaranteed solution in the presence of negative data where the conventional data envelopment analysis models find difficulties in measuring the convex efficiency scores for the given set of alternatives. The two frontier approach is meant for enclosing each alternative inside the worst and best frontiers. Unlike the traditional data envelopment analysis models two convex efficiency scores are computed. inefficiency scores deduced from these two frontiers are then used for measuring a proximity score which ultimately discriminates the items into three categories.
    Keywords: directional distance model; TOPSIS; multi-criteria decision making; MCDM.

  • Application of Hat function for delay fractional optimal control problems
    by Amir Ahmad Khajehnasiri 
    Abstract: In this paper, we present a special class of fractional operational matrices to find the solution of the delay optimal control problems of fractional order. The solution is based on the Hat functions. Despite the complexity of the solution for delay systems, the most advantages of using Hat functions are the efficiency, reliability, and simplicity. To illustrate the proposed method, some numerical examples have been presented. Comparison with other methods and the numerical results show that the given numerical method is so accurate and effective to find the approximate solution of fractional delay systems as well as the delay fractional optimal control problems.
    Keywords: delay; Hat functions; operational matrix; optimal control problems; block pulse function; BPF.

  • Modelling and simulation of multi-compartment vehicle routing problems to transport different types of solid waste
    by Yousra Bouleft, Ahmed Elhilali Alaoui 
    Abstract: : The waste management problem is an important sign of development in every city in the world. In this work, we introduce a new scheme that divides the entire waste management system into three levels: 1) transfer separated solid waste from different sources to the compartmentalised transfer station, each compartment accommodating one or more supplies of the same type of waste; 2) transport the separated solid waste from the transfer station to the treatment plants, each plant belonging to a specific specialty via a compartmentalised fleet; 3) transfer the waste produced from the treatment plants to the nearest landfill. In this context, we present mathematical formulations of the waste management system using linear programs. Since the problem is NP-hard, we adapt a genetic algorithm to solve the second level. Numerical experiments show that after adapting our proposed approach, we get high-quality solutions to collect and transport a large quantity every day.
    Keywords: multi-compartment vehicle routing problems; solid waste management system; separated solid waste transport; genetic algorithm.

  • A simple use of OR techniques to complete seismic records without magnitude value   Order a copy of this article
    by M.C.M. Rodrigues, C.S. Oliveira 
    Abstract: We are working on modelling the phenomenon of seismic occurrences in the Azores region which requires, among other characteristics, the knowledge of the magnitude of past events. Approximately 18,000 seismic records are available, but more than 3,000 (17%) have no information on magnitude. In this paper, we propose a methodology to generate the missing values of magnitude. This is based on an unusual but very simple application of OR, where pseudo-random values of magnitude are generated according to the statistical distribution of magnitude in records where information is complete. Special care is exercised on the upper tail of the distribution. The procedure does not determine the magnitude of an earthquake at a specific date, but the records become more complete in the sense that the generated values have a statistical distribution identical to the observed values. Statistical tests and the confirmation of the Gutenberg-Richter law validate the methodology.
    Keywords: natural phenomena simulation; simulation to complete missing values; upper tail generation; OR application; magnitude estimation; seismic process of occurrences; earthquake hazards; Azores.
    DOI: 10.1504/IJOR.2022.10047772
  • The impact of project network topology and resource restrictions on the performance of schedule generation schemes: a comparative study
    by Raafat Elshaer 
    Abstract: Parallel, and serial schedule generation schemes (SGS) are the core of most heuristic solution procedures for the resource-constrained project scheduling problem. The solution-quality of the generated schedules using the two schemes depends on the projects network topology and resource restrictions. According to the most recent publication, the network topology is measured using four indicators: serial/parallel, activity distribution, length of arcs, and topological float, whereas resource restrictions are assessed using two parameters: resource use and resource-constrainedness. The main objective is to investigate the impact of the projects network topology and resource parameters on the performance of the two schemes. A study-based generated datasets has been applied using a genetic algorithm with the two schemes. The computational results demonstrate that out of four indicators, serial/parallel has the most significant impact on distinguishing between the performance of the two SGS schemes. Moreover, resource use also impacts the discrimination between the two schemes
    Keywords: project network topology; resource-constrained project; schedule generation schemes; SGS.

  • Optimal testing resource allocation for software system: an approach combining interval-valued intuitionistic fuzzy sets and AHP
    by Rubina Mittal, Rajat Arora, Anu Gupta Aggarwal 
    Abstract: Among all the phases of the software development process, testing consumes the majority of the total available resources. Therefore, it is vital to efficiently manage the testing resources for the development of quality software. In this study, we propose an approach for allocating the resources optimally among the modules of the software system considering the quality characteristics discussed in the literature. The methodology incorporates interval-valued intuitionistic fuzzy analytic hierarchy process (IVIF-AHP) in the optimisation problem to maximise the reliability of the software subject to the availability of resources. Optimisation is grounded on Weibull testing effort-dependent failure phenomenon considering change point and logistic fault reduction factor. The weights obtained for modules through IVIF-AHP are further used in prioritising them in the optimisation problem. The detailed methodology has been discussed followed by a numerical illustration.
    Keywords: interval-valued intuitionistic fuzzy sets; analytic hierarchy process; AHP; resource allocation; software reliability growth model; SRGM; testing effort; optimisation.

  • A Conditional Value-at-Risk (CVaR) approach to studying the Sustainable Crude Oil Supply Chains (SCOSCs) evolved due to change in government policies   Order a copy of this article
    by Davoud Ghahremanlou, Wieslaw Kubiak 
    Abstract: Recently US oil and bioethanol industries have faced drastic economic damage due to the 2020 Saudi Arabia-Russia oil price war and coronavirus disease (COVID-19), resulting in many bankruptcies. Government policies have brought these two main industries together to ensure sustainable crude oil supply chains, to combat global warming and energy insecurity. This motivated us to extend the study of Ghahremanlou and Kubiak (2021a) to protect the current and new SCOSCs against financial risks during economic crises by providing insights for the government and the investors, working to rescue the industries. We employ conditional value-at-risk, and develop a two-stage stochastic programming model. We perform a case study of the State of Nebraska by carrying out a computational experiment with 10,710 different policy scenarios. We recommend robust strategic investment decisions to businesses during policy changes within economic crises. We also identify resilient strategic investment decisions.
    Keywords: COVID-19; conditional value-at-risk; CVaR; government policies; economic crises; sustainable crude oil supply chain; two-stage stochastic programming.
    DOI: 10.1504/IJOR.2022.10046294
  • Optimal Testing Resource Allocation for Software System: An approach combining Interval Valued Intuitionistic Fuzzy Sets and AHP   Order a copy of this article
    by RUBINA MITTAL, RAJAT ARORA, Anu G. Aggarwal 
    Abstract: Among all the phases of the software development process, testing consumes the majority of the total available resources. Therefore, it is vital to efficiently manage the testing resources for the development of quality software. In this study, we propose an approach for allocating the resources optimally among the modules of the software system considering the quality characteristics discussed in the literature. The methodology incorporates interval-valued intuitionistic fuzzy analytic hierarchy process (IVIF-AHP) in the optimisation problem to maximise the reliability of the software subject to the availability of resources. Optimisation is grounded on Weibull testing effort-dependent failure phenomenon considering change point and logistic fault reduction factor. The weights obtained for modules through IVIF-AHP are further used in prioritising them in the optimisation problem. The detailed methodology has been discussed followed by a numerical illustration.
    Keywords: interval-valued intuitionistic fuzzy sets; analytic hierarchy process; AHP; resource allocation; software reliability growth model; SRGM; testing effort; optimisation.
    DOI: 10.1504/IJOR.2022.10046600
  • The impact of project network topology and resource restrictions on the performance of schedule generation schemes: A comparative study   Order a copy of this article
    by Raafat Elshaer 
    Abstract: Parallel, and serial schedule generation schemes (SGS) are the core of most heuristic solution procedures for the resource-constrained project scheduling problem. The solution-quality of the generated schedules using the two schemes depends on the project’s network topology and resource restrictions. According to the most recent publication, the network topology is measured using four indicators: serial/parallel, activity distribution, length of arcs, and topological float, whereas resource restrictions are assessed using two parameters: resource use and resource-constrainedness. The main objective is to investigate the impact of the project’s network topology and resource parameters on the performance of the two schemes. A study-based generated datasets has been applied using a genetic algorithm with the two schemes. The computational results demonstrate that out of four indicators, serial/parallel has the most significant impact on distinguishing between the performance of the two SGS schemes. Moreover, resource use also impacts the discrimination between the two schemes.
    Keywords: project network topology; resource-constrained project; schedule generation schemes; SGS.
    DOI: 10.1504/IJOR.2022.10046619
  • A Fuzzy Economic Order Quantity Model for Multiple Stage Supply Chain with Fully Backlogged Shortages Derived without Derivatives under the Effect of Human Learning   Order a copy of this article
    by Richi Singh, Ashok Kumar, Dharmendra Yadav 
    Abstract: In industries, inventory managers face major difficulties in inventory planning when the available information fluctuates abruptly or is unclear. This ambiguity can be treated appropriately by using fuzzy sets. Moreover, human learning is effective in reducing the level of fuzziness over the infinite horizon. In the present study, a fuzzy three-stage (buyer-distributor-vendor) EOQ model is developed. In this model, all the cost parameters are taken as fuzzy parameters. Shortages are allowed but fully backlogged at the buyer end. The novelty of the paper lies in deriving the fuzzy model by using the arithmetic-geometric inequality method and proposing four theorems based on optimal frequency for vendor and distributor, along with incorporating the concept of learning in fuzziness. Some numerical examples are taken to demonstrate the model in a better way. Also, a comparison among the results of this paper, and other papers are done with the help of an example, which shows that the present model better represents the practical financial situations. At last, sensitivity analysis concerning all parameters and managerial insights are presented to justify the significance of the model.
    Keywords: supply chain; arithmetic geometric inequality; fuzzy costs; learning; backlogging.
    DOI: 10.1504/IJOR.2022.10046637
  • Comparative Study of Maximization Assignment Model by Existing Method and Newly Proposed Methods   Order a copy of this article
    by Agnivesh Tiwari, Kabir Chaudhary, Rahul Boadh, Yogendra Rajoria 
    Abstract: One of the simplest uses of linear programming is known as the assignment problem, which is a special case of the transportation problem. The assignment problem manages the inquiry about to dole out n-items to m-different items in the most ideal way for production planning, telecommunication, VLSI design, economics, etc. Many researchers developed newly proposed methods for solving assignment problems and others modified the Hungarian method. Therefore, in the present study, an effort has been made to solve the real-life balance and unbalance type profit maximisation assignment problem used by ten newly proposed methods such as MAP, MSEI, ATOC, NAZs and six others methods, and compared results with Hungarian method. This study found that Method 8 takes the least time for computation of both type problems as compared with other methods. This paper advocates that new researchers and scientists may use the newly proposed Method 8 in place of the existing method.
    Keywords: assignment problem; Hungarian method; optimal solution; profit maximisation.
    DOI: 10.1504/IJOR.2022.10046644
  • Application of Hat function for delay fractional optimal control problems   Order a copy of this article
    by Amirahmad Khajehnasiri, Reza Ezzati, Mostafa Safavi, Akbar Jafari 
    Abstract: In this paper, we present a special class of fractional operational matrices to find the solution of the delay optimal control problems of fractional order. The solution is based on the Hat functions. Despite the complexity of the solution for delay systems, the most advantages of using Hat functions are the efficiency, reliability, and simplicity. To illustrate the proposed method, some numerical examples have been presented. Comparison with other methods and the numerical results show that the given numerical method is so accurate and effective to find the approximate solution of fractional delay systems as well as the delay fractional optimal control problems.
    Keywords: delay; Hat functions; operational matrix; optimal control problems; block pulse function; BPF.
    DOI: 10.1504/IJOR.2021.10046675
  • On the number of occupied resources in a system with resource sharing between service-oriented customers   Order a copy of this article
    Abstract: We present analytical and generalised expressions of the numbers of occupied resources in a system providing several services to its customers. This system can be assimilated to a multi-service queue. We considered that the required numbers of resources for each service are deterministic, then random variables number of resources is studied in second part. Analysis carried out on the resource occupations have made possible the dimensioning of the total number of necessary resources that must be deployed on the queue server. They are to serve the customers up to a certain quality of service in terms of the probability of congestion. Reported to a single-service case, we found from the analytical expressions established in this work the probability of congestion in the Fry-Molina traffic model. The results are illustrated with numerical case studies.
    Keywords: queueing; dimensioning; multi-service; resource occupation; resource sharing.
    DOI: 10.1504/IJOR.2022.10046726
    by Dharmendra Yadav, Dinesh K. Sharma, S.K. Yadav 
    Abstract: To enhance the performance of an estimator, the use of additional information on study variables instead of the auxiliary variables may be a good alternative in survey sampling as it does not increase the survey cost. One of the examples of such additional information is the use of the median of the main variable. As there is no need for full information on units of the population under consideration for the median, so many times it is known to us. In the present article, we have developed an extended ratio estimator for the population mean utilising a given population median of the study variable. We have driven out the expressions for Bias of suggested estimator along with its MSE up to the approximation of degree one. The optimal value of the characterising scalar has also been derived using the method of maxima and minima. The conditions under which the suggested estimator is more efficient than previous estimators are also obtained. Our findings, in theory, are supported by the numerical illustration consisting of three different natural populations. The efficiency of the suggested estimator over competing estimators is also presented in the form of graphical representation.
    Keywords: median; ratio estimator; bias; MSE; efficiency.
    DOI: 10.1504/IJOR.2021.10046753
  • Optimal route selection model in freight transport with customer collection approach using genetic and fuzzy algorithms   Order a copy of this article
    by Mohammad Saeid Erfannejad, Ali Paydar, Salman Safavi 
    Abstract: In this research, a vehicle routing problem model is presented by considering fuzzy capacity, where vehicles must collect goods from various customers and return them to the central building via the shortest route possible. since customers inaccurately declare space needed for freight transport and the size of cargo being collected is not clear hence proving necessary to use fuzzy logic in modelling the vehicle routing problem. Therefore, after generalising the vehicle routing problem to the fuzzy model and considering the two parameters of remaining capacity and occupied capacity, the details of a framework based on the metaheuristic genetic optimisation algorithm is introduced to solve this optimisation problem. According to the results from 10 scenarios where the vehicle problem is obtained through this research via Matlab software, it could be concluded that solutions from the genetic algorithms with crossover and mutation operations are always converged with fuzzy constraints for the vehicle routing problem.
    Keywords: optimal route; genetic algorithms; freight transport; fuzzy; customer.
    DOI: 10.1504/IJOR.2021.10046754
  • International Journal of Operational Research: A Retrospective Overview between 2005 and 2020   Order a copy of this article
    by Santosh Baheti 
    Abstract: The study presents a retrospective analysis of the International Journal of Operational Research (IJOR) across its 16 years of publication, 2005 to 2020. IJOR is a journal of international repute that publishes original and peer-reviewed research in the management sciences, decision sciences, and operation research domain. The journal reached its 17th year of publishing in 2021. This study provides a comprehensive overview of 1,023 publications using the bibliometric data analysis technique. The study focuses on the contribution of IJOR to the knowledge domain through publishing trends, authorship patterns, dominant authors, prominent articles, nature of studies, and thematic analysis. Co-occurrence analysis of all keywords, co-authorship, citation and co-citation analysis of authors, countries, and institutions is performed through VOS Viewer software. The findings of the study emphasise the relationship of IJOR to different fields.
    Keywords: bibliometrics; Scopus; operational research; VOS Viewer.
    DOI: 10.1504/IJOR.2021.10047331
  • Solution of a mining equipment maintenance system model in imprecise environment   Order a copy of this article
    by Ashok Kumar Shaw, Mostafijur Rahman, Sankar Prasad Mondal, Banashree Chatterjee, Shariful Alam 
    Abstract: In this paper, a mining equipment maintenance system is depicted by a mathematical model described in terms of a pair of differential equations. The impreciseness involved in a real-life situation is accounted in this paper letting the initial condition and associated parameters to be imprecise in nature. Two most popular mathematical knowledge dealing with the sense of uncertainty, namely the fuzzy and interval environments are utilised here to analyse and solve the proposed model under uncertainty. The solutions of the uncertain differential equations (both interval and fuzzy) corresponding to the model are getting inspired by the generalised Hukuhara derivative of a set valued function. Different crispification techniques of converting the fuzzy and interval solutions into their crisp representatives are manifested to compute and compare the score of feasible decisions under uncertainty.
    Keywords: mining equipment maintenance problem; generalised Hukuhara derivative; fuzzy differential equation; FDE; interval differential equation; removal area method; mean of centre method.
    DOI: 10.1504/IJOR.2022.10047628
  • MSTL: A Seasonal-Trend Decomposition Algorithm for Time Series with Multiple Seasonal Patterns   Order a copy of this article
    by Kasun Bandara, Rob Hyndman, Christoph Bergmeir 
    Abstract: The decomposition of time series into components is an important task that helps to understand time series and can enable better forecasting. Nowadays, with high sampling rates leading to high-frequency data (such as daily, hourly, or minutely data), many datasets contain time series data that can exhibit multiple seasonal patterns. Although several methods have been proposed to decompose time series better under these circumstances, they are often computationally inefficient or inaccurate. We propose a procedure to decompose time series with multiple seasonal patterns that is suited to a wide range of high-frequency data. The procedure for multiple seasonal trend decomposition (MSTL) introduced in this paper extends the traditional seasonal-trend decomposition using Loess (STL) algorithm, allowing the decomposition of time series with multiple seasonal patterns. In our evaluation on synthetic and a perturbed real-world time series dataset, compared to other decomposition benchmarks, MSTL demonstrates competitive results with lower computational cost. The implementation of MSTL is available in the R package forecast.
    Keywords: time series decomposition; multiple seasonality; MSTL; TBATS; STR.
    DOI: 10.1504/IJOR.2022.10048281
  • Analysis of (MAP, PH)/(PH, PH)/1 Retrial Queueing Model with Standby Server, Collision of Orbital Customers, Breakdowns, Two-way communication, Phase Type Repairs, Constant Retrial Rate and Impatient Behaviour of Customers   Order a copy of this article
    by AYYAPPAN Govindan, Thilagavathy Karthikeyan 
    Abstract: Having modelled our system using standby server whenever the main server unavailable due to breakdowns and analysed the constant retrial policy for the orbital customers. The incoming arrival (IA) of customers follows the Markovian arrival process (MAP). The outgoing arrival (OA) of customers, service for both incoming and outgoing arrival of customers, repairs are all based on the phase-type (PH) distributions. Using Matrix analytic method, we investigate the steady state probability vector of the system. We described the busy period, cost analysis of the system and some characteristics of the system measures. We evaluate some numerical and graphical representation for the elucidation of our proposed model.
    Keywords: PH Distribution; MAP; Standby Server; Impatient Behaviour; Constant retrial rate; Two-way Communication.
    DOI: 10.1504/IJOR.2022.10048364
  • The Effect of Lead-Time Variability on Inventory: Expected On-Hand Inventory Vs. Safety Stock   Order a copy of this article
    by Xiaoming Li, Chunxing Fan 
    Abstract: Many papers and textbooks use safety stock as the inventory performance measure. But, this is only an approximation. Moreover, the lead-time variability causes conflicting effects on safety stock. In this paper, we argue that the right performance measure should be the expected on-hand inventory, which is consistent with the standard newsvendor problem. Then, the results always call for lead-time variability reduction, which always reduces both the expected on-hand inventory and the expected shortage inventory. These results are consistent and also indicate increased fill rates or service levels. We further show that the expected on-hand inventory and the expected shortage inventory are convex functions. When lead-time variability increases, lead-time demand spreads out further to both left and right tails, and thus causes higher expected on-hand inventory, higher expected shortage inventory, and higher cost. We finally present numerical examples to show managerial insights for decision makers in industry.
    Keywords: Lead-time reduction; Safety stocks; Expected on-hand inventory.
    DOI: 10.1504/IJOR.2021.10048762
  • Transient analysis of a Markovian N-policy queue with system disaster repair closedown setup times and control of admission   Order a copy of this article
    by A. Azhagappan, T. Deepa 
    Abstract: The main objective of this research work is to study the time-dependent behaviour of performance measures and probabilities for an M / M / 1 queueing model with some interesting parameters such as closedown, setup periods, disastrous breakdown of the system, repair, N-policy and different control mechanism for the arrivals when the server is under repair as well as busy. In order to reduce the cost of production and to increase the profit, the manufacturing industries follow a technique of not to start the service until the number of work pieces reaches a fixed threshold value. Shutting down the machines when no jobs are available and setting up before the commencement of service play significant contributions to reach the goals in business organisations. The probabilities of the model under consideration are derived by the method of generating function for the transient case. Some system performance measures and numerical simulations are also presented.
    Keywords: N-policy queue; disaster and repair; closedown and setup times; control of admission; transient probabilities.
    DOI: 10.1504/IJOR.2021.10025819
  • State-of-the-art in optimisation and heuristics to solve manufacturing scheduling problem   Order a copy of this article
    by Puja Bharti, Sushma Jain 
    Abstract: Manufacturing scheduling is known to be one of the most complex optimisation problems and falls in the category of NP-hard problems. Continuous efforts have been made by the researchers in the past to find convincingly accurate solutions for the instances in a reasonable time. It is valuable to compile the abundant literature available in this area for better understanding as well as convenience. This survey presents a systematic review of the optimisation approaches to solve manufacturing scheduling problem. Primarily, the research published during the period 2001-March 2019 has been considered. For this, a total of 456 research papers were examined. A comprehensive, well-informed examination and realistic analysis of the available literature provides an insight into major developments that has taken place pertaining to the use of heuristics/meta-heuristics in solving this problem. A classification based on objectives, optimisation techniques, benchmark instances, software tools, etc., highlights the research trends in this field along with future directions.
    Keywords: optimisation; heuristics; NP-hard; job shop scheduling; review; meta-heuristics; state-of-art; single objective; multi-objective; multi-objective evolutionary algorithms; MOEAs; manufacturing scheduling.
    DOI: 10.1504/IJOR.2022.10048486
  • Optimal deductible and coinsurance policies under mean-variance preferences   Order a copy of this article
    by Christopher Gaffney 
    Abstract: The paper presents a mean-variance analysis of optimal insurance coverage, showing how the relationship between the attitudes of the insured, in the form of their risk tolerance level, and the insurer, in the form of the insurance premium, affects insurance demand. Optimal parameter values (deductible, coverage limit, coinsurance level, and stop-loss limit) are derived, and policies which include coinsurance and either a stop-loss limit or a deductible reduce to a straight deductible policy in the optimum, are shown. Also shown was that straight coinsurance is inferior to these policies.
    Keywords: mean variance; optimal deductible; coinsurance; stop-loss; risk aversion.
    DOI: 10.1504/IJOR.2021.10026224
  • Modelling and optimisation of reverse logistics network under fuzzy environment   Order a copy of this article
    by Chandra Prakash Garg 
    Abstract: Resource recovery, environmental protection, sustainable production and consumption have got much attention in recent times because of growing ecological and social concern, economic issues and government regulations. In order to recover products, which include reuse, refurbishing, recycling and proper disposal of wastes that can help reduce their impact on environment, human and society, demands an effective reverse logistics (RL) network structure. In this paper, multi-product, multi-facility and multi-stage RL network is designed under uncertain environment and optimisation of the proposed network is analysed by fuzzy mixed integer linear programming (MILP) model with the aim of optimising total RL profit, quantity flows and facility locations. The proposed model is further supported by a numerical example of electronics products. Subsequently, the robustness of the model verifies the balanced relationship between the degree of feasibility and the degree of satisfaction of the management.
    Keywords: reverse logistics network; mixed integer linear programming; MILP; fuzzy; electronics products.
    DOI: 10.1504/IJOR.2022.10048487
  • Improved memetic programming algorithm   Order a copy of this article
    by Souhir Elleuch, Bassem Jarboui 
    Abstract: Automatic programming is an efficient technique that has contributed to an important development in the field of artificial intelligence. Genetic programming (GP) is a well known automatic programming algorithm based on genetic algorithm and evolves programs. In the present paper, we propose a new automatic programming method called two-dimensional memetic programming. It combines GP with local searches. We also introduce a new program representation for automatic programming algorithms. For this reason, the memetic programming algorithm is extended to evolve this program specific structure. To show the effectiveness of our method, we tested it on benchmark problems drawn from time series prediction and medical datasets classification, and we compared it with the related techniques.
    Keywords: genetic programming; memetic programming; local search; time-series forecasting; classification.
    DOI: 10.1504/IJOR.2021.10032941
  • An exact approach to the integration of non-cyclical preventive maintenance scheduling and production planning for a series-parallel production system   Order a copy of this article
    by Abdessamad Ait El Cadi, Nizar El Hachemi, Mohamed Anouar Jamali, Abdelhakim Artiba, Louis-Martin Rousseau 
    Abstract: In this paper, we generalise a model for integrated non-cyclical preventive maintenance scheduling and production planning from a single machine to a series-parallel production line. As for a single machine, we consider a set of products that must be produced in lots during a given time horizon. The maintenance strategy involves possible preventive replacements at the beginning of each maintenance period and minimal repair at machine failure. The model, an integer linear program, determines the optimal production plan and preventive replacement for each machine of the production line. The objective is to minimise the total cost (preventive and corrective maintenance costs, setup costs, holding costs, backorder costs, and production costs) while meeting the demand for each product over the horizon. We performed experiments using CPLEX 12.5.1, and almost all instances were solved within five minutes with a reasonable gap.
    Keywords: production planning; preventive maintenance; series-parallel production line; integer linear program; CPLEX.
    DOI: 10.1504/IJOR.2021.10028946