International Journal of Operational Research (146 papers in press)

Regular Issues

• An EOQ model for non-instantaneous deteriorating items with time-dependent quadratic demand and two-level pricing strategies under trade credit policy.  
  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
   
  
• Hybridized Ant Colony Optimization for the Multi-depot Multi-compartment capacitated arc routing problem  
  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  
  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
   
  
• A Classical Retrial Queueing Inventory System with Two Component Demand Rate  
  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  
  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  
  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  
  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
   
  
• Comparative Analysis between Serial Systems with Cold Standby Units  
  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  
  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  
  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  
  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  
  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  
  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  
  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  
  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
   
  
• How to Bring Manufacturing Back?  
  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  
  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
   
  
• INVENTORY MODEL FOR THE GROWING ITEMS WITH PRICE DEPENDENT DEMAND, MORTALITY AND DETERIORATION  
  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  
  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
   
  
• Statistical distribution and analysis of secondary queue of railway passengers  
  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
   
  
• ORDER PICKING AND STORAGE OPTIMIZATION IN A WAREHOUSE USING AGENT BASED MODELING  
  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  
  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  
  by Toky RAVALIMINOARIMALALASON, Mirisoa RAKOTOMALALA, Falimanana RANDIMBINDRAINIBE 
  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  
  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  
  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  
  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
   
  
• Improving healthcare services in Trauma Emergency Centre for patient safety under COVID-19 pandemic crises  
  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  
  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  
  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 Metaheuristic for the Multiple Minimum Latency Problem with the Min-Max Objective  
  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
   
  
• An Optimization-Simulation Framework for Integrated Inventory and Cash Replenishment Problem of Automated Teller Machines in India  
  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  
  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  
  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  
  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  
  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  
  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  
  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.  
  by SAURABH SRIVASTAVA 
  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  
  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  
  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
   
  
• Analyzing a queueing network of the emergency department with deteriorating health in post-disaster situations  
  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  
  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  
  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  
  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  
  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  
  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  
  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  
  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  
  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  
  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  
  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  
  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  
  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
   
  
• Pascal’s Triangle Graded Mean Defuzzification Approach For Solving Fuzzy Assignment Models by Using Pentagonal Fuzzy Numbers  
  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  
  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  
  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  
  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  
  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  
  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  
  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  
  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  
  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  
  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  
  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  
  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  
  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  
  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  
  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  
  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  
  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  
  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  
  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  
  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  
  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  
  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  
  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  
  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  
  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  
  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  
  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  
  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  
  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  
  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  
  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  
  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  
  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
   
  
• 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  
  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  
  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  
  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  
  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  
  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  
  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  
  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  
  by Toky RAVALIMINOARIMALALASON, Mirisoa RAKOTOMALALA, Falimanana RANDIMBINDRAINIBE 
  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
   
  
• A NEW GENERALIZED MEDIAN BASED ESTIMATOR OF THE FINITE POPULATION MEAN  
  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  
  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  
  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  
  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  
  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  
  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  
  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
   
  
• Performance Analysis of Reverse Osmosis System using Reliability Availability Maintainability and Dependability (RAMD) Technique  
  by Anas Maihulla, Ibrahim Yusuf 
  Abstract: Reverse osmosis systems have recently made significant contributions to the growth of renewable filtered water sources. RAMD (reliability, availability, maintainability, and dependability) is an engineering tool for addressing operational and safety risks in systems. It seeks to identify a system's weakest areas in order to improve overall system dependability. Elaborate RAMD analysis of these systems is presented starting from the subsystem level, then the overall system. Further, an improved reliability block diagram is presented to estimate the RAMD performance of six practical reverse osmosis system. A novel approach is also presented in order to estimate the best probability subsystem. The monitoring of the critical subassemblies of reverse osmosis system will increase the possibility not only for improving the availability of the system, but also to optimise the mean time to the system failure (MTTF). It will also inform the operators about the status of the various subsystems of the system.
  Keywords: reverse osmosis; reliability; availability; safety; maintainability; subsystems; dependability.
  DOI: 10.1504/IJOR.2021.10049213
   
  
• A Novel Technique for Solving Bi-Level Linear Fractional Programming Problems with Fuzzy Interval Coefficients  
  by Nejmaddin Sulaiman, Gulnar Wasim, Basiya Kakawla 
  Abstract: In this paper, a bi-level linear fractional programming problem (BILLFPP) with fuzzy interval coefficient (FIC) is contemplate where really all of it is coefficients in the goal function and constraints are fuzzy intervals (FIs). Firstly, to resolve this issue, we are going to construct two LFPP with fuzzy coefficients. Before all else, of these issues is a LFPP where all of coefficients are upper approximations of FIs and the other is a LFPP where all of coefficients are lower approximations of FIs. Secondly, the BILLFPP is transformed to the form of single goal LFPP and QFPP. We address problems with a factorised or non-factorised optimisation problem and homogeneous or non-homogeneous constraints. Our proposed technique is based on a mathematical model that converts the QFPP to a LPP by solving the problem in an algebraic expression with a Taylor series. This technique, which is based on the LPP solution, can be applied to specific problems. NLFPP containing nonlinear constraints, on iterative processes, it decreases the overall processing time. To explain, the novel technique for solving BILLFPP by taking numerical examples and compare with Jayalakshmi (2015) and Syaripuddin et al. (2017).
  Keywords: LFPP; bi-level linear fractional programming problem; BILLFPP; FBILLFPP; BILLFPP with fuzzy interval; FBILLFPP with FIC; QFPP; Taylor series; a novel technique.
  DOI: 10.1504/IJOR.2022.10049559
   
  
• An integrated Systematic Layout Planning (SLP), Analytical Hierarchy Process (AHP) and Non-Linear Programming (NLP) approach to facility layout design  
  by Vikas Singla 
  Abstract: This study has three aims: 1) finding alternative layout designs through procedural approach of SLP of a large-scale auto component manufacturer; 2) examine optimality of identified alternatives by using both qualitative and quantitative criteria and ranking them by using AHP method by collecting data from decision-makers of similar 132 manufacturers; 3) identifying most optimal design by using mathematical optimisation model of NLP. Results of SLP provided three prominent quantitative criteria by comparing key performance indicators of four alternative designs with those of existing layout. Informal discussions extracted major qualitative criteria. Rating of all six criteria indicated distance and cost of change being primary influencers. Results of NLP were able to identify one most optimal alternative from feasible four derived from SLP. The study derives its originality by dealing with shortcoming of SLP approach of over emphasis on subjective criteria and of metaheuristic methods of assigning excessive importance to metaheuristic methods.
  Keywords: facility layout; systematic layout planning; SLP; analytic hierarchy process; AHP; nonlinear programming; NLP; quadratic assignment problem; QAP.
  DOI: 10.1504/IJOR.2022.10049593
   
  
• PROPOSAL OF A NUMERICAL APPROXIMATION THEORY TO SOLVE THE ROBUST CONVEX PROBLEM OF PRODUCTION PLANNING  
  by Marcelo Gonçalves, Rafael Wollmann, Raimundo Sampaio 
  Abstract: his research seeks to solve the production planning problem modelled as a queuing system to propose to managers a production planning model that uses efficient, simple and robust methods. First, a robust mathematical model of nonlinear programming was proposed considering the concepts of queuing systems to estimate production capacity. Next, this model was approximated by a family of affine functions using the strategy of approximating a convex set by a polyhedral set. Finally, a theorem was proposed to demonstrate that a robust nonlinear programming model can be approximated by a robust linear programming model. From a numerical experiment with data from an electronic equipment company, it was possible to observe the effectiveness of the approximation method.
  Keywords: robust optimisation; linear programming; convex programming; queuing systems.
  DOI: 10.1504/IJOR.2022.10049618
   
  
• Optimal Location Prediction for Emergency Stations using Machine Learning  
  by Prasham Sheth, Praxal Patel, Priyank Thakkar 
  Abstract: Time is a critical aspect in emergency circumstances like medical crises, natural disasters, breaking out of a fire, etc. The average response time of emergency services is on the rise in recent times owing to the growing traffic. This has raised some serious concerns for people’s safety. It is easy to perceive that optimally located emergency stations (e.g., ambulance, fire station) can help in these situations by minimising travel time to reach the location of casualty. With this motivation, we propose an approach which employs K-medoids driven by extreme gradient boosting (XGBoost) for predicting optimal locations of emergency stations. The proposed approach is validated on real datasets, namely: New York City, USA 100-metre Grid Coordinates, NYC Taxi Trip Duration, KNYC Metars 2016 and FDNY Firehouse Listing dataset and the results demonstrate that the proposed method reduces normal average response time and allows serving more locations.
  Keywords: emergency station; optimal location prediction; OLP; machine learning; XGBoost; K-medoids; average response time.
  DOI: 10.1504/IJOR.2022.10049826
   
  
• An EOQ Model for Deteriorating Item with Ramp type Linear Time Dependent Demand and Time Dependent Partial Backorder  
  by Prokash Mondal, Asim K. Das, Tapan Kumar Roy, Surajit Naskar 
  Abstract: In this present article we have developed an economic order quantity (EOQ) model over a finite time horizon for an item with a liner time dependent demand rate with constant rate of deterioration in consideration of shortages (SFI policy) in inventory under permissible delay in payments and partial backlogging. Studied witnessed that the demand always play a pivot role in the inventory model, due to COVID crisis there is a shift in the paradigm on the demand characteristics. This model studied the shifting demand rate after stock out period. Mathematical models are also developed under two distinct circumstances, i.e., case 1: the trade credit is before the stock out period and case 2: the trade credit scheduled after stock out period. The results are illustrated with numerically and graphically. The sensitivity analysis of key parameters of the optimal solution has also been conducted to study the effect of the parameter.
  Keywords: inventory; economic order quantity; EOQ; deterioration; delay in payment; trade credit; backlog dependent.
  DOI: 10.1504/IJOR.2022.10049855
   
  
• Linearization of Non-Linear Programs using the Essence of Calculus and Integer Programming  
  by Matthew Zilvar 
  Abstract: This paper contains an approach to solve nonlinear programming (NLP) problems using a linearisation approach based on theorems of calculus. The solution method relies upon dividing functions with finite domains into a series of domains and coefficients used to model linear and nonlinear functions within a mixed integer linear program (MILP). Nonlinear terms are solved for in the objective function and constraints while achieving global optimality at a specified resolution using the international system of units (SI). An efficient solution method is provided by creating a set of MILPs that represent the same problem with different complexities and using the solutions to achieve global optimality. Numerical results and a comparison are provided. From the results an argument in the P versus NP problem is formed.
  Keywords: linearisation; nonlinear programming; integer programming; P vs. NP; calculus; logarithmic programming; transportation problem; set forming; complexity theory; global optimality.
  DOI: 10.1504/IJOR.2022.10050354
   
  
• A Comparison of a novel single reference point Multi-Attribute Decision Making Method with EDAS method  
  by Sirine Boujelben, Mohamed Souissi 
  Abstract: The present work aims to introduce a new method called the evaluation based on deviation from median attribute values (EDMAV) to solve the multi-attribute decision problems. This method is based on the deviation of each alternative from to the reference median solution with respect to each criterion. However, the proposed method combines the results of two different models to get the global score of each alternative, namely weighted arithmetic mean (WAM) and weighted median model (WMed). A ranking of alternatives is performed based on the value of a joint generalised criteria computed according to the results of these models. The proposed method is applied on illustrative example in order to illustrate its applicability, usefulness, and effectiveness and it has been compared with the evaluation based on distance from average solution (EDAS) method.
  Keywords: multi-attribute decision; operational research; weighted median; average; single reference point.
  DOI: 10.1504/IJOR.2022.10050398
   
  
• A Double-Pivot Degenerate-Robust Simplex Algorithm for Linear Programming  
  by Yaguang Yang, Fabio Vitor 
  Abstract: A double pivot simplex algorithm that combines features of two recently published papers by these authors is proposed. The proposed algorithm is implemented in MATLAB. The MATLAB implementation is tested, along with a MATLAB implemention of Dantzig’s algorithm, for several test sets, including a set of cycling linear programming problems, Klee-Minty’s problems, randomly generated linear programs, and Netlib benchmark problems. The test results show that the proposed algorithm, with a careful implementation is: 1) degenerate-robust as expected; 2) more efficient than Dantzig’s algorithm for large size randomly generated linear programming problems, but less efficient for Netlib benchmark problems and small size randomly generated problems in terms of CPU time.
  Keywords: double pivots; degenerate-robust; simplex method; linear programming; Klee-Minty cube.
  DOI: 10.1504/IJOR.2022.10050447
   
  
• Three phases algorithms in solving full fuzzy transportation problem by using fuzzy analytical hierarchy process  
  by Muhammad Sam'an, Farikhin Farikhin, Bayu Surarso 
  Abstract: In the fuzzy transportation problem, the ranking function is widely used to order fuzzy number or convert fuzzy number to crisp number. Its process is easy to understand and implement. However, the ranking fuzzy number still has significant weakness in which there is still subjectivity or do not pay attention to real life such that sometimes the input and output disconnected the fully fuzzy transportation problem (FFTP) such as there is negative fuzzy optimal solution. In some cases, it was found that FFTP had equal values of the fuzzy distribution least costs such that the existing methods will be generated two or more fuzzy initial basic feasible values. The proposed algorithm, i.e., three-phase algorithm-based fuzzy AHP is capable to obtain the fuzzy optimal solution of FFTP. Based on the numerical example used to evaluate the performance of the three phases algorithm. The computational performances have been compared to the existing methods in the literature and the results shown this algorithm can solve the FFTP with similar values fuzzy optimal solution even better minimal solutions than existing methods.
  Keywords: fuzzy number; fully fuzzy transportation problem; FFTP; ranking function; fuzzy AHP; fuzzy optimal solution.
  DOI: 10.1504/IJOR.2021.10050449
   
  
• General finite approximation of noncooperative games played in staircase-function continuous spaces  
  by Vadim Romanuke 
  Abstract: A method of general finite approximation of N-person games played with staircase-function strategies is presented. A continuous staircase N-person game is approximated to a staircase N-dimensional-matrix game by sampling the player’s pure strategy value set. The method consists in irregularly sampling the player’s pure strategy value set, finding the best equilibria in
  Keywords: game theory; payoff functional; staircase-function strategy; multidimensional-matrix game; approximate equilibrium consistency; equilibrium stacking.
  DOI: 10.1504/IJOR.2022.10050526
   
  
• DEVELOPMENT AND VALIDATION OF A HYBRIDIZED ALGORITHM INVOLVING AHP AND MACHINE LEARNING FOR AUTOMOBILE VEHICLE SELECTION  
  by Sanjeev Kumar, Ashirbad Sarangi, Rakesh P. Badoni, R.P. Mohanty 
  Abstract: The problem of selecting an automobile has always been one of the most complex decisions to make, given a person’s social and economic life. It is often resolved either through a qualitative judgement of vehicles or through multiple criteria decision-making (MCDM) methods in an algorithmic way. However, the modern machine learning (ML) procedures have surfaced themselves as efficient techniques in the field of recommendation engines (REs) to predict the items that may be useful to the customers according to their preferences. In this paper, an attempt has been made to study the automobile vehicle selection (AVS) problem in an innovative manner by hybridising the analytic hierarchical process (AHP) with the collaborative filtering (CF) technique to construct a selector to recommend the customers precisely one pair of cars that would suit best to their preference. The proposed algorithm provides an efficient way to map the satisfaction level of the customers by eliminating the vagueness and complexity in the selection process. We have validated the algorithm using real-life datasets collected by administering an exploratory survey across geographies, including India.
  Keywords: multiple criteria decision-making; MCDM; analytic hierarchical process; AHP; automobile vehicle selection; AVS; collaborative filtering; CF; recommendation engine.
  DOI: 10.1504/IJOR.2022.10050616
   
  
• Modelling MX/G/1 queuing system with optional second service under disaster and repairs with multiple adapted vacation policy  
  by S. Jeyakumar, B. Logapriya 
  Abstract: In this article, the queuing system with disaster is considered in which every customer will receive the essential service and demanded customer alone will receive second optional service. When the system is affected by any of the disaster, the server initiates the repair period and operates under multiple adapted vacation (MAV) policy causing all waiting and served customer to leave the system. Using supplementary variable technique, we procure the queue size distribution with few measures of performance. Expected queue length, expected waiting times and certain special cases are discussed. In addition, the effect of parameters is studied with a numerical illustration.
  Keywords: supplementary variable technique; second optional service; disaster; multiple adapted vacation policy.
  DOI: 10.1504/IJOR.2022.10050810
   
  
• A systematic literature review to measure lean, green and agile in manufacturing organisations  
  by Fadwa Bouhannana, Akram Elkorchi 
  Abstract: Most manufacturing companies are mainly interested in strengthening competiveness by concentrating on competitive priorities. The majority of companies have started implementing lean, green and agile paradigms in order to become more efficient and highly productive. To achieve those objectives, researchers around the world have been increasingly interested in developing tools to control the process of implementing these three paradigms in organisations. In this context, various approaches have previously been proposed in the literature. Consequently, a systematic review of measurement methods, such as leanness, greenness and agility, in manufacturing organisations was performed for the purpose of defining some guidance for managers and practitioners who are interested in measuring these three concepts. Therefore, 121 methods have been selected and analysed based on a set of comparative dimensions. The main strengths and weaknesses of the selected approaches are mentioned. Some literature gaps are highlighted, and a number of directions are provided for future research.
  Keywords: manufacturing; leanness; greenness; agility; literature review; score.
  DOI: 10.1504/IJOR.2022.10050966
   
  
• A multi-objective portfolio selection problem with parameters as interval type fuzzy set.  
  by Jayanti Nath, Sanjoy Chhatri, Debasish Bhattacharya 
  Abstract: A multi-objective portfolio selection problem with fuzzy parameters is studied here based on the possibility concept of fuzzy set theory. Here, for a given degree of membership ? of the fuzzy parameters, the problem has been reduced to an equivalent crisp problem. This reduced problem is then solved by the min-max goal programming (GP) method in one step. This approach gives the decision maker the flexibility to choose the solution of the problem for an assigned degree of satisfaction ? and concomitant risk (1
  Keywords: portfolio optimisation; fuzzy multi-objective linear programming; capital growth; return; risk; liquidity; dividend; min-max GP.
  DOI: 10.1504/IJOR.2022.10051487
   
  
• Applying Mathematical Modeling to the Factor Analyses of Obtaining GASR Funds for Universities in Japan  
  by Masashi Miyagawa, Takuro Matsumoto, Atsushi Inoue, Tatsuo Oyama 
  Abstract: First, we briefly explain the historical trend of the Japanese competitive research funding system, focusing on the grants-in-aid for scientific research (GASR). We provide mathematical models, such as logistic curves and Zipf’s model, to explain the trend of budgets for research promotion funds and their allocation to Japanese universities and research institutions. Subsequently, we evaluate the performance of Japanese universities from the perspective of obtaining GASR funds using Gini coefficients. We then build multiple regression models to quantitatively investigate the factors that determine and affect the dependent variables, such as the number of accepted GASR projects and number of distributed funds of the GASF projects, in which independent variables including the number of undergraduate students, external funds, operating expenses grants, and operating expenses grants to all university-specific project expenses, or the ratio of external funds per faculty member, may also be considered as influential factors. We apply multivariate analysis techniques such as cluster analysis and principal component analysis to determine the key factors for obtaining GASR, to classify Japanese universities with respect to their recent scenario for obtaining GASR funds and reveal the determining factors underlying these results.
  Keywords: competitive research fund; scientific research fund; mathematical model; logistic curve; Zipf’s model; multiple regression model; cluster analysis; principal component analysis.
  DOI: 10.1504/IJOR.2022.10051636
   
  
• Priority Study on Commodity Market Operation and Performance for Indian Investors  
  by Sanat Rout, Sadananda Sahoo, Rabindra Kumar Mishra 
  Abstract: The present research explores the investors’ behavioural intention towards the commodity market in an emerging economy. Drawing cues from the extant literature, this research identifies and empirically prioritises the dimensions of investor intention regarding commodity trading. Based on the RIDIT analysis, the findings indicate that a lower degree of risk, geopolitical changes, and a higher rate of return are the most important dimensions based on the respondent perceptions. These findings offer newer insights on this under-explored domain to facilitate conceptual development and policy formulation. The portfolio managers, market regulators, and financial institutions can take cues from the study findings to redesign their strategies for attracting investors to commodity exchanges.
  Keywords: commodities; investor; behavioural intention; emerging economy; RIDIT.
  DOI: 10.1504/IJOR.2022.10051839
   
  
• On state dependent batch service queue with single and multiple vacation under Markovian arrival process  
  by Gagan Kumar Tamrakar, Anuradha Banerjee 
  Abstract: : An infinite buffer batch service vacation queue has been studied where service rate of the batch is dependent on the size of the batch and vacation rate is dependent on the queue size at vacation initiation epoch. The arrivals follow the Markovian arrival process (MAP). For service rule, general bulk service (GBS) rule is considered. The service time and vacation time both are considered to be generally distributed. Several joint distributions of interest are obtained using the bivariate vector generating function method and the supplementary variable technique (SVT). Numerical results are presented to show the behaviour of the system performance to validate the analytical results.
  Keywords: Markovian arrival process; infinite buffer; GBS rule; bivariate VGF; supplementary variable technique.
  DOI: 10.1504/IJOR.2022.10052122
   
  
• On Solving Game Problem using Octagonal Neutrosophic Fuzzy Number  
  by R. Narmada Devi, S. Sowmiya 
  Abstract: Game theory deals with competitive situation where there are two or more opposing parties with conflicting interests are involved. A competitive situation will be called a game. In this paper, a new approach for selecting a best strategy for increasing the shares for two companies using octagonal neutrosophic fuzzy number is proposed. Further, convert a octagonal neutrosophic fuzzy number to neutrosophic fuzzy number by using deneutrosophication and finally get the fuzzy number by using fuzzification method. The obtained matrix represents fuzzy game matrix. This matrix is solved using game theory to obtain the best strategy for these companies.
  Keywords: octagonal neutrosophic fuzzy number; ONFN; DTNON: de-neutrosophication of trueness; DINON: de-neutrosophication of indeterminacy; DFNON: de-neutrosophication of falsity.
  DOI: 10.1504/IJOR.2022.10056357
   
  
• Multi-Echelon Reverse Supply Chain Network Design using New Ant Colony Optimization Algorithms  
  by Mostafa Ashour, Raafat Elshaer 
  Abstract: Reverse logistics (RL) is becoming more important in the general area of the industry due to environmental and business factors. Planning and implementing a suitable RL network can lead to more benefits, customer satisfaction, and a nice social image for businesses. Since such network design challenges belong to the NP-hard problem class, three proposed ant colony algorithms that differ in the heuristic information, and artificial pheromone trail calculation rules were developed to solve a designed distribution-allocation problem in multi-stage RL network with a fixed transportation cost in distribution network as well as variable cost of the route. Five network characteristics with different sizes are designed, and thirty instances are randomly generated for each network characteristic to evaluate the performance of the three developed ant colony optimisation (ACO) algorithms. Computational analysis of the results reveals the high quality and validity of the developed ACO algorithms when compared with the exact results.
  Keywords: logistics network; forward/reverse supply chain; single-objective; ant colony optimisation; ACO.
  DOI: 10.1504/IJOR.2022.10052168
   
  
• A LINMAP Approach for Determining Subjective Attribute Weights for Neutrosophic Multi Attribute Decision Making Models  
  by S. Paulraj, G. Tamilarasi 
  Abstract: The linear programming technique for multidimensional analysis of preference (LINMAP) is one of the well-known methods involved to solve multi-attribute decision-making (MADM) problems. Many authors developed LINMAP method based on fuzzy and intuitionistic fuzzy environment. In this paper, we develop a new method called neutrosophic Linear programming technique for multidimensional analysis of preference (LINMAP), which combines the single valued neutrosophic sets with LINMAP method. This paper establish the conventional LINMAP method to a neutrosophic MADM framework using single valued trapezoidal neutrosophic numbers and we obtain the attributes weight and ideal solution. A practical example is provided to show that our method is very effective for solving MADM problems with single valued trapezoidal neutrosophic number information. Comparative analyses with existing method are also furnished to shows the advantage of our proposed method.
  Keywords: single valued trapezoidal neutrosophic number; LINMAP; consistency and inconsistency measures; multi-attribute decision making; MADM.
  DOI: 10.1504/IJOR.2022.10052436
   
  
• Parallelization of multiple traveling salesman problem without returning to the starting node  
  by Vadim Romanuke 
  Abstract: A method of heuristically solving the non-classic multiple travelling salesman problem is suggested, where a dramatic computational speedup is guaranteed. The salesmen covering the route must not return to the starting node in this problem. A specific genetic algorithm is the solver. To get the speedup, the nodes should be separable so that they could be divided into two or more groups. Every two adjacent groups are connected by a node called the isthmus. The respective subproblems are solved independently, in parallel, whereupon their subroutes are aggregated through the isthmuses. This shortens the aggregated route on average, although it may be slightly longer in specific cases. Such an accuracy loss is 1% to 2% in the worst case for a few hundred thousands to millions of nodes, but instead the saved computational time is counted in days, weeks, and months. The efficiency of such a parallelisation dramatically grows as more isthmuses as distinct node group separators are found. If two successive subroutes are covered by the same number of salesmen, the constraint of that every node can be visited only by one salesman is easily satisfied by correcting the subroutes at the isthmus.
  Keywords: multiple travelling salesman problem; route length; genetic algorithm; parallelisation; isthmus; node group separability.
  DOI: 10.1504/IJOR.2022.10052526
   
  
• Effect of Quadratic Price-Dependent demand with Quadratic Time-Dependent Demand in EOQ Inventory Models for Deteriorative items  
  by Selvaraju P, Sivashankari C.K. 
  Abstract: This research focuses on impact of quadratic price-dependent and time-dependent demand in EOQ inventory models for deteriorative products in higher-order equations is examined in this article. Linear, constant, exponential, quadratic, stock dependent, price dependent, and other demand models have been discovered in the literature. In real practice, the price of the item and the time it takes to sell has a significant impact on the demand rate. Three models are developed: Quadratic time-dependent and price-dependent demands are used in the first model. In second model quadratic-time dependent and in the third model quadratic price dependent demands are used. The aim of this study is to identify the optimum cycle time and the optimum quantity that minimises the total cost. Each model has its own set of mathematical models. A sensitivity analysis is performed after solving and studying many numerical examples. Visual Basic 6.0 was used to create the required data.
  Keywords: EOQ inventory; quadratic price-dependent demand; quadratic time-dependent demand; integrate; optimality; sensibility analysis.
  DOI: 10.1504/IJOR.2022.10053350
   
  
• Examining Interrelationship amid Behavioural Biases affecting Investment Decisions- using DEMATEL Approach  
  by Manika Sharma, Mohammad Firoz, Neha Gupta 
  Abstract: Decision-making in choosing the investment alternative is a tough task. There are several factors that affect the investment decisions. One such factor is the behavioural biases that affect the decision of investor while making the investments. This study aims in studying the cause-and-effect relationship between the various behavioural biases. For this purpose, 11 biases have been identified through the literature review. Then, by using a prepared questionnaire on linguistic scale, data have been collected through 70 portfolio managers and decision-making trial and evaluation laboratory (DEMATEL) technique is used to find the interrelationship between these biases. Identified behavioural biases are also ranked according to the magnitude of influence that affects the investor in the decision-making process. The paper will contribute to the current literature on behavioural finance, and it will also help the portfolio managers to develop a precise strategy whereby they may select a biased free investment avenue and can design a strong portfolio for investors and can save them from making incorrect decisions which result into flawed outcomes.
  Keywords: behavioural biases; decision-making; DEMATEL.
  DOI: 10.1504/IJOR.2021.10053397
   
  
• A Vendor-Managed Inventory Model for Deteriorating Products  
  by Anyarin Sakrujiratham, Huynh Trung Luong 
  Abstract: This paper develops a vendor-managed inventory model for deteriorating products in a two-level supply chain which is comprised of one vendor and one retailer in the case when the time to deterioration of the product follows Weibull distribution. It is assumed that the market demand is price-sensitive and shortages are fully backlogged. The proposed inventory model helps to determine the replenishment cycle length and the optimal replenishment quantity to help minimise the total cost of the entire supply chain. Numerical experiments and sensitivity analyses are conducted to illustrate the applicability of the proposed model. Some future research directions are also discussed.
  Keywords: vendor-managed inventory; VMI; inventory control; deteriorating products; supply chain management.
  DOI: 10.1504/IJOR.2022.10053513
   
  
• A novel hybrid BSC-DEA model for performance assessment in knowledge enterprises using balanced scorecard and data envelopment analysis approach  
  by Bakhtiar Ostadi, Masoud Sadri, Ehsan Nikbakhsh 
  Abstract: The importance of knowledge enterprises (knowledge-based companies) in countries’ economies and their role in GDP has recently increased, and many efforts have been made to achieve a comprehensive and consistent benchmark and model for evaluating these companies. Therefore, the purpose of this paper is to provide a hybrid model for performance assessment in knowledge enterprises. So, the primary indicators have been extracted by reviewing the literature and structure of knowledge enterprises. After collecting data from knowledge enterprises and combining the balanced scorecard (BSC) and data envelopment analysis (DEA) approach, a hybrid BSC-DEA model developed to assess the partial efficiency of each unit and the total efficiency of each knowledge enterprises. Finding mentioned that the ability of start-ups and knowledge enterprises to be compared with large and old ones. Also, there will be no significant difference in the performance of companies with respect to their type.
  Keywords: performance assessment; knowledge enterprises (knowledge-based companies); data envelopment analysis; DEA; balanced scorecard; BSC.
  DOI: 10.1504/IJOR.2023.10053850
   
  
• Optimizing Production and Operational Cost in a Limestone Mine by MINLP Approach: An End-to-End Case Study  
  by Anindita Desarkar, Aaditya Umasankar, Viswa Janith Paidisetty, Abhishek Sarma, Santosh Kumar Annabattula Venkata Varaha, Vishwanathan Raman, Mahesh Mahajan 
  Abstract: Prediction is always a challenging task; it gets harder especially in mining where lots of complexities and uncertainties are present in the system. Optimizing the production output by adhering to the ore quality, minimizing fuel consumption towards operational cost reduction, maximizing utilization and minimizing the idle time of the fleets are a few major goals in the mining industry. However, all these things depend upon the optimal distribution of resources and equipment in appropriate places. Though manual allocation can be one solution, but optimal result is not always achieved because it's quite difficult to optimize so many parameters on a day-to-day basis. The present research proposes a multistage and multi-objective optimization approach based on mixed integer non-linear programming to achieve the aforesaid goals. The experimental results show the efficacy of the method, and it is also implemented in one real mine scenario where all the above-mentioned goals are achieved.
  Keywords: Optimization; Mixed-Integer Non-linear programming; Production maximization; Fuel minimization; Resource allocation; Utilization; Productivity; Truck dispatching.
  DOI: 10.1504/IJOR.2023.10053952
   
  
• Waste Management by Bilevel Optimisation: A Survey  
  by Massimiliano Caramia, Emanuele Pizzari 
  Abstract: Waste Management is a complex and broad field of research. In problems falling under this category, several decision-makers have conflicting objectives and hierarchies. Therefore, the common approaches of single-objective optimisation or multiobjective optimisation may fail to capture the nuances of the situation. Hierarchical problems are best handled from a mathematical optimisation point of view via bilevel programming. In this paper, we survey contributions modelling waste management issues employing bilevel optimisation, a relatively new yet promising field of research. We start by providing a general analysis of these contributions and then describe the latter in macro-subjects. Finally, we draw some conclusions by providing open problems and follow-ups.
  Keywords: Bilevel optimisation ; Waste management ; Literature review.
  DOI: 10.1504/IJOR.2022.10054097
   
  
• A Production Model for Deteriorative items with Time Dependent Demand and Possible Adjustment of the Production Rate  
  by Sivashankari C.K., Valarmathi R. 
  Abstract: In this paper, two different rates of production problem of production inventory system for deteriorative items having constant demand, linear demand as well as quadratic demand is considered and in order to cut costs, it is preferable to begin production at a low rate (X1) and gradually increase to a higher rate (X2) over time. This is because starting with a low rate of production prevents an excessive quantity of manufactured goods from being stored at the outset. The variability in production rate offers a means both of resulting in the happiness of customers and of generating possible profit. There will be three models created. There is a consideration of demand that is constant demand in the first model, demand that is linear demand in the second model, along with quadratic demand in the third model. In all models, triangular inequality is used for evaluating production time and Bernoulli’s integration is used for integration in all three models.
  Keywords: Constant; Linear and Quadratic Demands; Two Rates of Productions; Optimality and comparative study.
  DOI: 10.1504/IJOR.2023.10054233
   
  
• Multi-objective optimization of surplus food recovery and redistribution units in India  
  by Nistha Dubey, Ajinkya N. Tanksale 
  Abstract: Food banks are not-for-profit organizations that collects surplus and leftover food and distribute it to unfortunate people of society with an aim to alleviate hunger. The problem can be modeled as multi depot-VRP. We endeavour three primary objectives of food banks - efficiency, effectiveness, and equity. The measure for efficiency is minimum total transportation cost, minimum total shortage for effectiveness, and minimum of the maximum shortage of network is taken for equity. This paper proposes a MILP model for multi-objective optimization of surplus food recovery and redistribution in India. Our study is the first to evaluate Indian food banks from a multi-objective perspective. To solve the proposed problem, state-of-the-art-solver Gurobi is used for weighted sum method, augmented ?-constraint method, and augmented weighted Tchebycheff methods. Non-Sorted Genetic Algorithm is developed to solve the larger network problems. The results of the computational experiments show significant trade-off behavior between efficiency and effectiveness.
  Keywords: Food banks; VRP; Multi-depot; NSGA-II; Multi-objective; Split loads.
  DOI: 10.1504/IJOR.2023.10055079
   
  
• Interaction Model Development in Determining House Prices by Using Goal Programming  
  by Nerda Zura Zaibidi, Nor Syuhaddah Saiddin, Adyda Ibrahim, Siti Aisyah Saupi 
  Abstract: The buyer, the real estate developer, and the government are typically the three main parties engaged in housing projects. The interaction between these parties affects the housing market, particularly the prices of homes. The interaction has become more difficult because of the disparities in preferences between the parties. The ideal strategy for creating a fruitful partnership between these parties is still a mystery. As a result, this study has established a decision maker interaction model for getting mutual understanding on a housing project. Goal programming and a simulation method were used in this work to develop a successful interaction model. The average dwelling price that all the parties had mutually agreed upon was represented by the mean value of RM 169,878 and it is skewed between RM 85,000 and RM 350,000. The results of this study can be used by developers in Malaysia to design homes that are affordable and appealing to buyers, preventing problems with long-term unsold homes.
  Keywords: interaction model; house prices; multi-objective optimisation; goal programming.
  DOI: 10.1504/IJOR.2023.10055108
   
  
• Genetic and Hybrid algorithms to solve the container stacking problem at Tripoli-Lebanon seaport.  
  by Nobar Kassabian, Zakaria Hammoudan, Olivier Grunder, Lhassane Idoumghar 
  Abstract: Several factors determined the survival of the seaport: logistics, storage and distribution. A storage strategy dependent on container stacking rules is an important factor in the competence of the container terminal. This article focuses on solving the problem of stacking incoming containers in the storage yard, taking into account several criteria regarding the port of Tripoli-Lebanon. A mathematical model with a mixed integer linear program for the container stacking problem is considered in this paper. As this problem is NP-hard, large instances cannot be solved by optimisation solvers as Gurobi. We develop four algorithms to tackle this problem: a genetic algorithm (GA), a randomised greedy algorithm (RGA), an iterated local search (ILS) and a hybridisation approach between RGA and ILS. Finally, numerical simulations prove the efficiency of the GA which produces results close to the optimal solution on real instances taken from the containers terminal for small and medium sizes.
  Keywords: container stacking problem; CSP; mathematical modelling; optimisation; Gurobi optimiser; genetic algorithm; GA; randomise greedy algorithm; RGA.
  DOI: 10.1504/IJOR.2023.10055823
   
  
• Metaheuristic-based approaches for the multi-centre open home healthcare routing problem  
  by Bilal Kanso, Ali Kansou, Adnan Yassine 
  Abstract: This paper presents the multi-centre open home healthcare (MC-OHHC) problem with time windows and synchronisation constraints. The MC-OHHC can be described as the problem of designing least cost routes from several centres to a set of visits, without forcing them to return to the centres. Some services require simultaneous visits by using different routes to be accomplished. The contribution of the paper is three-fold: 1) it presents the corresponding mathematical linear model; 2) it gives the results related to the CPLEX resolution and an adapted constructive heuristic solution of such a problem; 3) it provides the results related to a variable neighborhood descent algorithm, a simulating annealing algorithm and a hybrid genetic algorithm. Computational results on adapted set of benchmark instances from the literature are reported and show that our proposed approaches are fast, efficient and competitive compared to the solutions provided by the CPLEX software. Some optimal solutions are provided in short computational times, and greatly improve the initial solutions obtained by the proposed efficient constructive method.
  Keywords: home healthcare problem with multi-centres; window time; synchronisation; constructive heuristic; variable neighbourhood descent metaheuristic; simulating annealing metaheuristic.
  DOI: 10.1504/IJOR.2023.10056210
   
  
• Energy Demand Forecasting Using A Novel Optimised Fourier Grey Markov Based Approach  
  by Noorshanaaz Khodabaccus, Aslam A. E. F. Saib 
  Abstract: Energy supply affects the sustainable development of an economy, hence making its modelling and forecasting crucial to policymakers. Conventional statistical models often require either prior assumptions on the distribution of the data or large historical datasets. This paper proposes the optimised Fourier-Markov grey model (OFGM), which alleviates the former two assumptions. Two test scenarios are proposed for assessing the model's performance: data prior to the COVID-19 pandemic (20102019) and data extending over the pandemic period (20102020). Numerical experiments demonstrate that the proposed algorithm very well models both scenarios and a significant improvement in the prediction accuracy is achieved.
  Keywords: grey prediction model; Fourier; Markov; metaheuristic algorithm; energy forecasting.
  DOI: 10.1504/IJOR.2023.10056840
   
  
• The Reduction of Realized Variance in Deductible Insurance  
  by Christopher Gaffney 
  Abstract: We derive a series of mathematical identities that connect insurance purchasers with insurance companies. In particular, we focus on the way in which variance is shared between the parties. We argue that, from the perspective of governmental oversight, a desirable property of insurance is that the total amount of variance experienced by the involved parties is smaller under an insurance contract than in the uninsured case. It is shown that this always holds in the case of a single insurer and a single insured, while for the case of a single insurer and multiple insured, we derive a condition which guarantees the relationship.
  Keywords: deductible insurance; Affordable Care Act; ACA; insurance coverage; mean-variance analysis; variance reduction.
  DOI: 10.1504/IJOR.2023.10056842
   
  
• A State Dependent Arrival Analysis In a Non-Markovian Bulk Queue with Server Failures  
  by Palaniammal S, Pradeep S 
  Abstract: Breakdown brings a huge impact in the queueing system which causes complicated consequences. This paper comprises the results of functioning and malfunctioning of the queueing system due to continuous server breakdown. This work examines the failure of the server without interruption in state-dependent arrivals and numerous vacations. Even if a failure happens, the Server is not stopped for maintenance before finishing a batch of service. The queue size PGF at an irrational time period, as well as the probability generating functions of vacation, service, and renovation completion epochs, are derived using the additional variable technique. The queueing system's unique qualities and key features are provided, along with a cost model. An extensive numerical research is done using real-world examples.
  Keywords: state dependent arrivals; server breakdown; supplementary variable method; queue; bulk service; multiple vacations; cost model.
  DOI: 10.1504/IJOR.2023.10056844
   
  
• De-i-fuzzification of linear interval-valued intuitionistic fuzzy number and its application in operation research arena  
  by Avishek Chakraborty, Shilpi Pal, Sankar Prasad Mondal, 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: linear IVIFN; ranking; distance measure; de-i-fuzzification; inventory control; transportation problem.
  DOI: 10.1504/IJOR.2020.10038562
   
  
• Factors affecting suppliers' capacity in outsourcing: a study of the Water and Wastewater Company of Iran  
  by Hadi Sarvari, Masoud Raeisi Dehkordi, Daniel W.M. Chan, Matteo Cristofaro, Nerija Banaitienė 
  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 - based on 50 items categorised into four groups: judicial-legal, contract, management and financial - was developed based on prior literature and experts' answers. Respondents have been asked to evaluate each item with regard to the capacity of suppliers in outsourcing processes on a five-point Likert scale. Factor analysis, one-sample t-test and the Friedman test were used for data analysis. Results show that the factor categories able to increase the capacity of suppliers in outsourcing processes at WWC are the following, in order of importance: financial, judicial-legal, contracts and management. The findings help to focus on shortcomings and deficiencies of current outsourcing processes.
  Keywords: water industry; wastewater industry; outsourcing; Delphi; supplier capacity; Iran.
  DOI: 10.1504/IJOR.2021.10035756
   
  
• Multi-item EOQ model for deteriorating items having multivariate dependent demand with variable holding cost and trade credit  
  by Dharmendra Yadav, S.R. Singh, Manisha Sarin 
  Abstract: In the present study, a multi-item EOQ inventory model for deteriorating items is explored by considering customer's 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; multivariate demand; variable holding cost; partial backlogging; trade credit.
  DOI: 10.1504/IJOR.2020.10037238
   
  
• Absolute and relative weight restrictions in DEA - a comparison  
  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