Template-Type: ReDIF-Article 1.0 Author-Name: Nejah Ben Mabrouk Author-X-Name-First: Nejah Ben Author-X-Name-Last: Mabrouk Author-Name: Bassem Jarboui Author-X-Name-First: Bassem Author-X-Name-Last: Jarboui Author-Name: Mansour Eddaly Author-X-Name-First: Mansour Author-X-Name-Last: Eddaly Title: Solving the joint production distribution problem by the variable neighbourhood search algorithm Abstract: This paper addressed the dynamic integrated production routing problem where the objective is to minimise the total cost including production, inventory and distribution. Since this problem is NP-hard, we developed a variable neighbourhood search algorithm (VNS) to solve it. Therefore, two VNS algorithms were proposed: the first one is used to determine the produced quantity of each day and the second aims to determine the routing map. Insert and swap moves were used in the local search step. The obtained results showed the effectiveness of our proposed approach according to previous works, including greedy heuristic and memetic algorithm, in the literature. Journal: Int. J. of Mathematics in Operational Research Pages: 484-502 Issue: 4 Volume: 18 Year: 2021 Keywords: production planning; vehicle routing; inventory; variable neighbourhood search. File-URL: http://www.inderscience.com/link.php?id=114202 File-Format: text/html File-Restriction: Access to full text is restricted to subscribers. Handle: RePEc:ids:ijmore:v:18:y:2021:i:4:p:484-502 Template-Type: ReDIF-Article 1.0 Author-Name: Pushkar Jaisawal Author-X-Name-First: Pushkar Author-X-Name-Last: Jaisawal Author-Name: Tadeusz Antczak Author-X-Name-First: Tadeusz Author-X-Name-Last: Antczak Author-Name: Vivek Laha Author-X-Name-First: Vivek Author-X-Name-Last: Laha Title: On sufficiency and duality for semi-infinite multiobjective optimisation problems involving V-invexity Abstract: In the present paper, we study a non-convex non-smooth semi-infinite multiobjective programming problem with a finite number of Lipschitz continuous objective functions and infinite number of inequality constraints which is applicable in economics, engineering, optimal control theory, robust optimisation, social work and in different fields of mathematics. We derive sufficient conditions for the optimality of a feasible point under <i>V</i>-invexity and generalised <i>V</i>-invexity assumptions in terms of Clarke subdifferential. We formulate Mond-Weir type dual model for the primal non-smooth semi-infinite multiobjective programming problem and establish weak, strong and strict converse duality results under the <i>V</i>-invexity and generalised <i>V</i>-invexity conditions. The results established in the paper extend and unify several similar results in the literature. Journal: Int. J. of Mathematics in Operational Research Pages: 465-483 Issue: 4 Volume: 18 Year: 2021 Keywords: non-smooth analysis; semi-infinite optimisation; efficient solution; optimality conditions; Mond-Weir duality; V-invexity. File-URL: http://www.inderscience.com/link.php?id=114204 File-Format: text/html File-Restriction: Access to full text is restricted to subscribers. Handle: RePEc:ids:ijmore:v:18:y:2021:i:4:p:465-483 Template-Type: ReDIF-Article 1.0 Author-Name: Dipak Barman Author-X-Name-First: Dipak Author-X-Name-Last: Barman Author-Name: Anjana Kuiri Author-X-Name-First: Anjana Author-X-Name-Last: Kuiri Author-Name: Barun Das Author-X-Name-First: Barun Author-X-Name-Last: Das Title: A two-vehicle two-stage solid transportation problem with bi-fuzzy coefficients through genetic algorithm Abstract: This study deals a two-stage solid transportation problem where on in each stage and each path there are two different capacitated vehicles. As per the quantity of transportation, the larger and/or smaller capacitance vehicles are used. Moreover, the coefficients of the model are assumed bi-fuzzy in nature. The items are breakable in nature and to reduce the breakability rate of the item extra safety cost is introduced here. Finally, the model is justified through a numerical example by using evolutionary genetic algorithm. Also a statistical test illustrates and signifies the feasibility and validity of the proposed model and techniques with a high rate of probability. Journal: Int. J. of Mathematics in Operational Research Pages: 444-464 Issue: 4 Volume: 18 Year: 2021 Keywords: two-stage solid transportation problem; vehicle's capacity; bi-fuzzy; genetic algorithm; analysis of variance. File-URL: http://www.inderscience.com/link.php?id=114205 File-Format: text/html File-Restriction: Access to full text is restricted to subscribers. Handle: RePEc:ids:ijmore:v:18:y:2021:i:4:p:444-464 Template-Type: ReDIF-Article 1.0 Author-Name: Mohsen Shafiei Nikabadi Author-X-Name-First: Mohsen Shafiei Author-X-Name-Last: Nikabadi Author-Name: Hossein Fallah Moghaddam Author-X-Name-First: Hossein Fallah Author-X-Name-Last: Moghaddam Title: An integrated approach of adaptive neuro-fuzzy inference system and dynamic data envelopment analysis for supplier selection Abstract: In this study, in order to consider the future efficiency of suppliers as well as their precedent efficiency in supplier selection process, first, the input, output and link of the suppliers were forecasted by adaptive neuro-fuzzy inference system (ANFIS). Then, the future and precedent efficiency of the suppliers were determined using the forecasted values and dynamic DEA. Then, the more efficient supplier was selected with regard to the efficiency concepts. Some further studies have been also taken for application of the recommended procedure, as using the confirmatory factor analysis (CFA), the criteria including price, delivery, quality, service, eco-costs and capacity of electronic trading were considered for selection of suppliers. The findings indicated that the recommended method has more accuracy and less error for forecasting the efficiency of suppliers. Also, two candidates have been selected eventually as the most efficient suppliers of the company. Journal: Int. J. of Mathematics in Operational Research Pages: 503-527 Issue: 4 Volume: 18 Year: 2021 Keywords: supplier selection; adaptive neuro-fuzzy inference system; ANFIS; dynamic data envelopment analysis; efficiency. File-URL: http://www.inderscience.com/link.php?id=114206 File-Format: text/html File-Restriction: Access to full text is restricted to subscribers. Handle: RePEc:ids:ijmore:v:18:y:2021:i:4:p:503-527 Template-Type: ReDIF-Article 1.0 Author-Name: Mohanad Al-Behadili Author-X-Name-First: Mohanad Author-X-Name-Last: Al-Behadili Author-Name: Huda Zaki Author-X-Name-First: Huda Author-X-Name-Last: Zaki Author-Name: Khaldoun Al-Yasiri Author-X-Name-First: Khaldoun Author-X-Name-Last: Al-Yasiri Title: Locust swarm optimisation for the permutation flow shop scheduling problem Abstract: The permutation flow shop scheduling problem (PFSP) is one of the most prominent types of combinatorial optimisation problems. The fact comes from its wide applications in manufactures and industries. In this paper, the locust swarm optimisation algorithm (LO) is proposed to find high quality solution for the PFSP, it simulates the behaviour of locust swarm. In this work, the LO algorithm is adapted to solve the PFSP with the objective of minimising the makespan where a heuristic rule called smallest position value (SPV) is triggered to transform the random numbers into sequences of jobs. Then the NEH heuristic of Nawaz-Enscore-Ham is applied to generate good quality initial population. Also, a simple and efficient iterated local search method is employed to explore the solution space efficiently. An experimental study is discussed in this paper to evaluate the performance of the introduced algorithm. Different well-known PFSP benchmarks of small, medium and large size instances are used for this purpose. The computational and statistical studies demonstrate that the proposed algorithm is evidently outperforming the recent algorithms in obtaining better solutions. Journal: Int. J. of Mathematics in Operational Research Pages: 545-565 Issue: 4 Volume: 18 Year: 2021 Keywords: locust swarm optimisation algorithm; permutation flow shop scheduling problem; PFSP; NEH heuristic; local search method. File-URL: http://www.inderscience.com/link.php?id=114207 File-Format: text/html File-Restriction: Access to full text is restricted to subscribers. Handle: RePEc:ids:ijmore:v:18:y:2021:i:4:p:545-565 Template-Type: ReDIF-Article 1.0 Author-Name: Houria Djafri Author-X-Name-First: Houria Author-X-Name-Last: Djafri Author-Name: Soumia Kharfouchi Author-X-Name-First: Soumia Author-X-Name-Last: Kharfouchi Title: Unilateral 2D Markov-switching autoregressive model Abstract: For nonlinear two-dimensional spatial data, a 2D Markov-switching unilateral autoregressive model is defined. Strict stationarity is studied and parameter estimation via the variational expectation maximisation (VEM) algorithm is performed. First, a 2D Markov random field (<i>MRF</i>) is constructed for which an imposed causality allows to establish an analogy between this 2<i>D</i> <i>MRF</i> and the Markov chain representation. Based on the proposed 2<i>D</i> MRF, the 2<i>D</i> <i>MS</i>-<i>AR</i> model is defined under some necessary assumptions and useful notations. Finally, parameter estimation of the model is discussed paving the way to broad exploitation perspectives of the proposed 2<i>D</i> <i>MS</i>-<i>AR</i> processes to efficiently model several phenomena exhibiting a structural break in spatial data. Journal: Int. J. of Mathematics in Operational Research Pages: 433-443 Issue: 4 Volume: 18 Year: 2021 Keywords: Markov-switching autoregressive; regional volatility; Markov random field; MRF. File-URL: http://www.inderscience.com/link.php?id=114208 File-Format: text/html File-Restriction: Access to full text is restricted to subscribers. Handle: RePEc:ids:ijmore:v:18:y:2021:i:4:p:433-443 Template-Type: ReDIF-Article 1.0 Author-Name: Mohamed Abd Allah El-Hadidy Author-X-Name-First: Mohamed Abd Allah Author-X-Name-Last: El-Hadidy Author-Name: M. Fakharany Author-X-Name-First: M. Author-X-Name-Last: Fakharany Title: Optimal 3-dimensional search model to find the underwater randomly hidden target Abstract: The searcher's path for finding a 3-dimensional underwater randomly located target like a black box for the air plan crash is studied. The searcher moves along slinky-turn-spiral curve and starts its motion from a known point (<i>X</i><SUB align="right"><SMALL>0</SMALL></SUB>, <i>Y</i><SUB align="right"><SMALL>0</SMALL></SUB>, <i>Z</i><SUB align="right"><SMALL>0</SMALL></SUB>). We focus on the geometry features such as curvature and torsion of the search path for the target position that has a known distribution. The searcher is desired to search in an optimal manner by obtaining the optimal values of the curvature and the torsion that minimise the expected time for detecting the target. An illustrative example has been given to demonstrate the applicability of this technique. Journal: Int. J. of Mathematics in Operational Research Pages: 210-235 Issue: 2 Volume: 18 Year: 2021 Keywords: optimal search theory; trivariate normal distribution; slinky-turn-spiral; geometry features. File-URL: http://www.inderscience.com/link.php?id=112929 File-Format: text/html File-Restriction: Access to full text is restricted to subscribers. Handle: RePEc:ids:ijmore:v:18:y:2021:i:2:p:210-235 Template-Type: ReDIF-Article 1.0 Author-Name: P.V. Ushakumari Author-X-Name-First: P.V. Author-X-Name-Last: Ushakumari Title: On a two-server reliability system with one-server idle below a threshold Abstract: In this work, we study a two-server <i>k</i>-out-of-<i>n</i>: <i>G</i> repairable system with identical components. Lifetimes of components follow an exponential distribution with parameter <i>λ</i>. For the repair of failed components, we consider two servers called server1 and server2 and the repair times are independent exponential random variables with parameters <i>μ</i><SUB align="right"><SMALL>1</SMALL></SUB> and <i>μ</i><SUB align="right"><SMALL>2</SMALL></SUB> (<i>μ</i><SUB align="right"><SMALL>1</SMALL></SUB> < <i>μ</i><SUB align="right"><SMALL>2</SMALL></SUB>) respectively for server1 and server2. It is assumed that server1 alone is active if the number of failed components is below a prescribed threshold say <i>N</i> (>1), whereas both servers are active above that threshold. That is, activating server2 only when the number of failed components reaches the threshold <i>N</i> and when it falls below that threshold, switch off the server. It will again reactivate only on the accumulation of <i>N</i> units. We obtained the system state distributions in finite time and the steady-state, by analysing a continuous time Markov chain and derived several other characteristics of the system such as system reliability, mean time to failure, mean busy period of the servers, etc. Also, we investigated a control problem and proved that the total expected cost of the system is convex in <i>N</i> and hence global minimum exists. Some numerical illustrations also provided. Journal: Int. J. of Mathematics in Operational Research Pages: 528-544 Issue: 4 Volume: 18 Year: 2021 Keywords: reliability; k-out-of-n system; busy period analysis; Markov chain; optimisation. File-URL: http://www.inderscience.com/link.php?id=114209 File-Format: text/html File-Restriction: Access to full text is restricted to subscribers. Handle: RePEc:ids:ijmore:v:18:y:2021:i:4:p:528-544 Template-Type: ReDIF-Article 1.0 Author-Name: Luis Felipe Godoy Vaca Author-X-Name-First: Luis Felipe Godoy Author-X-Name-Last: Vaca Author-Name: Javier Martínez Gómez Author-X-Name-First: Javier Martínez Author-X-Name-Last: Gómez Author-Name: Mario Fernando Bustamante Crespo Author-X-Name-First: Mario Fernando Bustamante Author-X-Name-Last: Crespo Author-Name: A. Jonathan Riofrio Trujillo Author-X-Name-First: A. Jonathan Riofrio Author-X-Name-Last: Trujillo Title: Energy analysis of adobe performance as a housing construction material in Ecuador Abstract: For housing construction designs in Ecuador, mechanical characteristics of constructive materials are highly prioritised instead of thermal considerations. In this sense, promoting the use of local materials with good energy efficient features appears as a suitable solution. As a consequence, in this article, energy performance of adobe is analysed in household energy performance. For this purpose, the following steps were taken: thermal characterisation of adobe (thermal conductivity). Adobe is obtained from quarries located in Pichincha province, Ecuador and its conductivity was the major thermal parameter tested. The research was carried out by means of experimental and statistical techniques. In addition, a strong state of the art review is presented, considering national and international standards. Finally, field tests show that adobe reaches an average conductivity around 0.22 W/m K. This value tends to increase due to the density of the sample and the technique used during the manufacture process. In addition, some studies demonstrate that by using adobe, for instance, on the frontage of a building, thermal comfort improves in some regions of the country, and energy consumption is reduced by 10%. Journal: Int. J. of Mathematics in Operational Research Pages: 154-168 Issue: 2 Volume: 18 Year: 2021 Keywords: energy performance; housing; thermal conductivity; adobe; Ecuador. File-URL: http://www.inderscience.com/link.php?id=112930 File-Format: text/html File-Restriction: Access to full text is restricted to subscribers. Handle: RePEc:ids:ijmore:v:18:y:2021:i:2:p:154-168 Template-Type: ReDIF-Article 1.0 Author-Name: Prem Prakash Mishra Author-X-Name-First: Prem Prakash Author-X-Name-Last: Mishra Author-Name: T. Poongodi Author-X-Name-First: T. Author-X-Name-Last: Poongodi Author-Name: S.K. Yadav Author-X-Name-First: S.K. Author-X-Name-Last: Yadav Author-Name: S.S. Mishra Author-X-Name-First: S.S. Author-X-Name-Last: Mishra Title: Algorithmic approach to time-cost analysis of queued commodity flowing through critical path Abstract: Here, an attempt has been made to develop an algorithm for optimisation of queued commodity flow under finite capacity constraints. It is a simulation of optimum queued commodity-flow in random network as an extension of Ford Fulkerson algorithm used in the notion of delivery scheduling. The execution of the queued commodity-flow through different routes of deliveries and its scheduling using CPM/PERT has been made. By this execution, the total delivery completion time is minimised in order to meet the scheduled time. Implementation of algorithm has been done through appropriate illustration of network to yield intended results for future application of the model. Final results are exhibited in three tables. Journal: Int. J. of Mathematics in Operational Research Pages: 169-186 Issue: 2 Volume: 18 Year: 2021 Keywords: cost function; development of algorithm; CPM/PERT; M/M/1/N queuing model. File-URL: http://www.inderscience.com/link.php?id=112934 File-Format: text/html File-Restriction: Access to full text is restricted to subscribers. Handle: RePEc:ids:ijmore:v:18:y:2021:i:2:p:169-186 Template-Type: ReDIF-Article 1.0 Author-Name: Oualid Saci Author-X-Name-First: Oualid Author-X-Name-Last: Saci Author-Name: Megdouda Ourbih-Tari Author-X-Name-First: Megdouda Author-X-Name-Last: Ourbih-Tari Title: Refined descriptive sample inference in the estimation of the cumulative distribution function Abstract: In this paper, we compare the estimators of the cumulative distribution function obtained by the refined descriptive (RD) sample and simple random (SR) sample, and show that the one obtained by RD sample is more efficient than that obtained by SR sample. For this purpose, we have compared the probability structure of RD sample and SR sample where the latter is generated using the principle of the RD sampling method. Simulation results of different distributions are given to validate the proposed theoretical comparison. Journal: Int. J. of Mathematics in Operational Research Pages: 264-287 Issue: 2 Volume: 18 Year: 2021 Keywords: refined descriptive sampling; RDS; Monte Carlo method; statistic order; multinomial vector; cumulative distribution function; cdf. File-URL: http://www.inderscience.com/link.php?id=112938 File-Format: text/html File-Restriction: Access to full text is restricted to subscribers. Handle: RePEc:ids:ijmore:v:18:y:2021:i:2:p:264-287 Template-Type: ReDIF-Article 1.0 Author-Name: Srikumar Acharya Author-X-Name-First: Srikumar Author-X-Name-Last: Acharya Author-Name: Berhanu Belay Author-X-Name-First: Berhanu Author-X-Name-Last: Belay Author-Name: Rajashree Mishra Author-X-Name-First: Rajashree Author-X-Name-Last: Mishra Title: Solving multi-objective chance constrained programming problem involving three parameters log normal distribution Abstract: The main point of this paper is to find the compromise solution of multi-objective chance constrained mathematical programming problem by considering the parameters of the right hand side restrictions as uncertain variables having three parameters log normal distribution. In the first step, we convert the multi-objective chance constrained mathematical programming problem to a deterministic equivalent multi-objective mathematical programming problem. After converting the multi-objective chance constrained programming problem into deterministic equivalent multi-objective programming problem, fuzzy programming method is used to find the solution which is closest to ideal solution. Numerical example is presented to illustrate the technique. Finally, case study on crop land and water management for irrigation is presented. Journal: Int. J. of Mathematics in Operational Research Pages: 236-253 Issue: 2 Volume: 18 Year: 2021 Keywords: operational research; multi-objective programming; chance constrained programming; deterministic programming; log normal distribution; fuzzy programming method; crop land management. File-URL: http://www.inderscience.com/link.php?id=112939 File-Format: text/html File-Restriction: Access to full text is restricted to subscribers. Handle: RePEc:ids:ijmore:v:18:y:2021:i:2:p:236-253 Template-Type: ReDIF-Article 1.0 Author-Name: Tanja Van Hecke Author-X-Name-First: Tanja Van Author-X-Name-Last: Hecke Title: Multiplicative determination of priority weights in a fuzzy analytic hierarchy process Abstract: Many application fields need evaluation tools and ranking techniques of several alternatives. The multi-criteria decision-making approach, known as the analytic hierarchy process, has yet been extended by a variant based on fuzzy logic, which is useful when dealing with uncertain judgements. This paper describes an important alternative method to determine the fuzzy priority weights of pairwise comparison matrices based on logarithmic calculus as a natural companion of the geometric mean. A significant advantage of our approach is the linear character of the resulting mathematical problem. The linearity allows the use of well-known linear programming techniques. The functioning of the method is illustrated by a numerical example which exposes the consistent way of priority weight determination. Journal: Int. J. of Mathematics in Operational Research Pages: 254-263 Issue: 2 Volume: 18 Year: 2021 Keywords: analytic hierarchy process; AHP; multi-criteria decision-making; MCDM; simplex method; priority weights; fuzzy logic; evaluation criteria; ranking. File-URL: http://www.inderscience.com/link.php?id=112940 File-Format: text/html File-Restriction: Access to full text is restricted to subscribers. Handle: RePEc:ids:ijmore:v:18:y:2021:i:2:p:254-263 Template-Type: ReDIF-Article 1.0 Author-Name: Andrés Villarruel-Jaramillo Author-X-Name-First: Andrés Author-X-Name-Last: Villarruel-Jaramillo Author-Name: Juan Carlos Rocha-Hoyos Author-X-Name-First: Juan Carlos Author-X-Name-Last: Rocha-Hoyos Author-Name: Edilberto Antonio Llanes Cedeño Author-X-Name-First: Edilberto Antonio Llanes Author-X-Name-Last: Cedeño Author-Name: Javier Martínez-Gómez Author-X-Name-First: Javier Author-X-Name-Last: Martínez-Gómez Title: Multi-criteria decision making for lower bumper stiffener material change in a sports utility vehicle with CAE simulation Abstract: This article describes the steps to replace the lower bumper stiffener material of a sport utility vehicle. It was taken as the main characteristics to obtain the behaviour principles as the lower bumper stiffener. A static structural simulation was developed according to the regulation of physical trials of the EuroNCAP. Three multi-criteria selection methods called TOPSIS, VIKOR and ENTROPY were applied. Polylactic acid was determined as the optimal material. A dynamic simulation between of the contact of the leg form impactor and pedestrian protection system, at a speed of 40 km/h was performed. The simulation evaluates the acceleration of the tibia, equivalent strain of Von Misses and deformation in the three nodes of the lower bumper stiffener. It was determined that the optimal material is the PLA, where it is appreciated that the main factors to consider for the decision making is the acceleration and the nodal deformation of the dynamic simulation. Journal: Int. J. of Mathematics in Operational Research Pages: 187-209 Issue: 2 Volume: 18 Year: 2021 Keywords: materials; lower bumper stiffener; LBS; MCDM; pedestrian protection system; PPS; CAE simulation. File-URL: http://www.inderscience.com/link.php?id=112943 File-Format: text/html File-Restriction: Access to full text is restricted to subscribers. Handle: RePEc:ids:ijmore:v:18:y:2021:i:2:p:187-209 Template-Type: ReDIF-Article 1.0 Author-Name: Sulekha Rani Author-X-Name-First: Sulekha Author-X-Name-Last: Rani Author-Name: Priyanka Agarwal Author-X-Name-First: Priyanka Author-X-Name-Last: Agarwal Author-Name: Madhu Jain Author-X-Name-First: Madhu Author-X-Name-Last: Jain Author-Name: Rahul Solanki Author-X-Name-First: Rahul Author-X-Name-Last: Solanki Title: A software reliability growth model considering testing coverage subject to field environment Abstract: Software reliability growth models are the basic models which predict essential information such as software cost and reliability required for the software development activities. It was assumed that the software behave in the field in the same way as they perform during testing but this assumption may not be true in every situation. In this paper, we discuss such a software reliability growth model which will predict the reliability according to the field environment incorporating two types of S-shaped testing coverage factors. Total expected cost (with warranty and risk cost) and optimal release time for the proposed reliability growth model is proposed. Numerical results using software 'MATLAB' help the software engineers for making their best decision. Journal: Int. J. of Mathematics in Operational Research Pages: 145-153 Issue: 2 Volume: 18 Year: 2021 Keywords: NHPP based SRGM; testing coverage; expected cost; risk cost. File-URL: http://www.inderscience.com/link.php?id=112944 File-Format: text/html File-Restriction: Access to full text is restricted to subscribers. Handle: RePEc:ids:ijmore:v:18:y:2021:i:2:p:145-153 Template-Type: ReDIF-Article 1.0 Author-Name: Mohamed Abd Allah El-Hadidy Author-X-Name-First: Mohamed Abd Allah Author-X-Name-Last: El-Hadidy Title: Existence of optimal N-slinky-turn-spiral search paths for finding N-dimensional Brownian target Abstract: This paper presents more effective search technique for finding the <i>N</i>-dimensional Brownian target in <i>N</i>-dimensional space by using <i>N</i>-searchers. Each searcher moves along slinky-turn-spiral curve and starts its motion from the origin. An adaptive geometric features such as curvature and torsion of each searching path to meet the target is proposed. Rather than showing the existence of finite and optimal search paths, we find these optimal search paths which minimise the expected value of the first meeting time between one of the searchers and the target based on its geometric characteristics and features. A simulation study has been discussed to demonstrate the applicability of this technique. Journal: Int. J. of Mathematics in Operational Research Pages: 180-203 Issue: 2 Volume: 19 Year: 2021 Keywords: optimal search theory; geometric features; N-dimensional Brownian target; first meeting time. File-URL: http://www.inderscience.com/link.php?id=116313 File-Format: text/html File-Restriction: Access to full text is restricted to subscribers. Handle: RePEc:ids:ijmore:v:19:y:2021:i:2:p:180-203 Template-Type: ReDIF-Article 1.0 Author-Name: Andres Mendez Author-X-Name-First: Andres Author-X-Name-Last: Mendez Author-Name: Javier Martínez-Gómez Author-X-Name-First: Javier Author-X-Name-Last: Martínez-Gómez Author-Name: Nicolalde Juan Francisco Author-X-Name-First: Nicolalde Juan Author-X-Name-Last: Francisco Title: Selection of a phase change material by using the multi-criteria selection method for use in an automotive thermal insulation system Abstract: The temperature that a car can reach inside is between 25°C to 40°C in certain environmental circumstances, for this reason studies have been carried out in the field of materials science that allow to control the interior environment of a car. This study proposes the use of alternative materials chosen through multi-criteria selection in order to apply them in thermal insulation, to control the interior temperature of the vehicle when it is parked. Starting from a list of candidate materials, the best material that meets the objective of constantly controlling the interior temperature of a car is determined by multi-criteria analysis, taking into accounts that when using a thermal insulation based on a PCM, an electrical control system would not be needed. It was determined that the ideal PCM for this application is paraffin, given its melting point that is 37°C. Journal: Int. J. of Mathematics in Operational Research Pages: 220-246 Issue: 2 Volume: 19 Year: 2021 Keywords: automobile; simulation; thermal storage; TES; phase change materials; PCMs; alternative materials; comparison; thermal insulation; energy; heat. File-URL: http://www.inderscience.com/link.php?id=116314 File-Format: text/html File-Restriction: Access to full text is restricted to subscribers. Handle: RePEc:ids:ijmore:v:19:y:2021:i:2:p:220-246 Template-Type: ReDIF-Article 1.0 Author-Name: Shaveta Kumari Author-X-Name-First: Shaveta Author-X-Name-Last: Kumari Author-Name: Saurabh Srivastava Author-X-Name-First: Saurabh Author-X-Name-Last: Srivastava Title: On optimality conditions for interval optimisation problems using generalised Hukuhara difference and constrained interval arithmetic Abstract: In the presented paper we derive necessary optimality conditions for mathematical optimisation problems which involve both objective function and inequality constraints in interval form. In the proposed work both objective function and inequality constraints are derived from continuous function. For the formation of continuous function we used the idea of generalised Hukuhara difference (gH-difference), generalised Hukuhara derivative and constrained interval arithmetic. The objective of this paper is to derive new necessary optimality conditions for interval valued optimisation problem on the basis of classical optimality conditions given by Karush-Kuhn-Tucker (KKT). Finally, the proposed conditions are illustrated with the help of numerical examples. Journal: Int. J. of Mathematics in Operational Research Pages: 204-219 Issue: 2 Volume: 19 Year: 2021 Keywords: generalised Hukuhara difference; generalised Hukuhara derivative; constrained interval arithmetic. File-URL: http://www.inderscience.com/link.php?id=116315 File-Format: text/html File-Restriction: Access to full text is restricted to subscribers. Handle: RePEc:ids:ijmore:v:19:y:2021:i:2:p:204-219 Template-Type: ReDIF-Article 1.0 Author-Name: Reza Jafari Author-X-Name-First: Reza Author-X-Name-Last: Jafari Title: Operational matrix method for solving Riccati differential equation by using hybrid third kind Chebyshev polynomials and block-pulse functions Abstract: The present operational matrix method reduces the Riccati differential equation to a system of algebraic equations. The algebraic system has been solved numerically by Tau method. Convergence analysis of the present method has been discussed in this article. Meanwhile, a numerical method is presented for solving Riccati differential equation. There has also been introduced the operational matrices of derivative and product based on hybrid third kind Chebyshev polynomials and block-pulse functions. Moreover, numerical examples have been included to demonstrate the validity and applicability of the technique. Journal: Int. J. of Mathematics in Operational Research Pages: 161-179 Issue: 2 Volume: 19 Year: 2021 Keywords: hybrid functions; Chebyshev polynomials; block-pulse functions; operational matrix of derivative; Riccati differential equation. File-URL: http://www.inderscience.com/link.php?id=116316 File-Format: text/html File-Restriction: Access to full text is restricted to subscribers. Handle: RePEc:ids:ijmore:v:19:y:2021:i:2:p:161-179 Template-Type: ReDIF-Article 1.0 Author-Name: R. Sivasamy Author-X-Name-First: R. Author-X-Name-Last: Sivasamy Author-Name: N. Paranjothi Author-X-Name-First: N. Author-X-Name-Last: Paranjothi Author-Name: Keoagile Thaga Author-X-Name-First: Keoagile Author-X-Name-Last: Thaga Author-Name: G. Paulraj Author-X-Name-First: G. Author-X-Name-Last: Paulraj Title: Poisson queues with Markov modulated service rates Abstract: In this paper we investigate an M/MM/1 queueing system that makes transitions between two service rates 'S(slow) and F(fast)' only at service completion epochs. Switching between these 'S and F' states occurs according to an embedded Markov chain rule. Both inter arrival times and service times follow exponential distributions. We also discuss an extension for an M/MM/1/(0, <i>N</i>] &cup; (<i>N</i>, &infin;) system. Under steady state conditions, the stationary probability distribution for the system size is obtained by spectral expansion method. To exemplify the tractability of the dynamics of the switching probabilities on the offered work load and the mean waiting time, we provide numerical illustrations. Journal: Int. J. of Mathematics in Operational Research Pages: 145-160 Issue: 2 Volume: 19 Year: 2021 Keywords: Markov modulated service; fast and slow service rates; stationary probability distribution. File-URL: http://www.inderscience.com/link.php?id=116317 File-Format: text/html File-Restriction: Access to full text is restricted to subscribers. Handle: RePEc:ids:ijmore:v:19:y:2021:i:2:p:145-160 Template-Type: ReDIF-Article 1.0 Author-Name: N. Sangeetha Author-X-Name-First: N. Author-X-Name-Last: Sangeetha Author-Name: B. Sivakumar Author-X-Name-First: B. Author-X-Name-Last: Sivakumar Author-Name: P. Anitha Author-X-Name-First: P. Author-X-Name-Last: Anitha Title: Optimal control of production time of perishable inventory system with postponed demands Abstract: We consider a continuous review production inventory system in which the demands arrive according to a Poisson process. We assume that the demands that occur during stock out periods enter a pool which has finite capacity. Any demand that arrives when the pool is full and the inventory level is zero, is also assumed to be lost. The demands in the pool are selected one by one, if the stock is above the prefixed value, with interval time between any two successive selections is distributed as exponential. In order to replenish stock, a production facility is switched on when the inventory level drops to prefixed value <i>s</i> and items are produced one by one until the stock level reaches a maximum capacity <i>S</i>(> <i>s</i>). The successive production time is assumed to follow an exponential distribution whose parameter is chosen from a given set of positive values. The objective of this paper is to investigate the optimal set of production rates that minimises the total expected cost per unit time. We formulate this problem as a semi-Markov decision problem. The stationary optimal policy is computed using linear programming algorithm and the results are illustrated numerically. Journal: Int. J. of Mathematics in Operational Research Pages: 129-144 Issue: 2 Volume: 19 Year: 2021 Keywords: inventory control; postponed demands; control of production rates; semi-Markov decision process; continuous review perishable inventory system. File-URL: http://www.inderscience.com/link.php?id=116343 File-Format: text/html File-Restriction: Access to full text is restricted to subscribers. Handle: RePEc:ids:ijmore:v:19:y:2021:i:2:p:129-144 Template-Type: ReDIF-Article 1.0 Author-Name: Mohamed Abd Allah El-Hadidy Author-X-Name-First: Mohamed Abd Allah Author-X-Name-Last: El-Hadidy Title: Stochastically escaping model in a tumour cell growth system driven by a Poisson process Abstract: We present a new model for the stochastic escaping phenomenon from the chemical treatment in a tumour cell growth system subjected to a Poisson process. This phenomenon has the same behaviour of the reneging units in <i>M</i>/<i>M</i>/1/<i>N</i> queue where these units have stochastically grown by a Poisson process. More than finding the statistical distribution of these cells (reneging units), we get the expected value and the variance of these units at any time. This time is depending on the total number of infected cells (<i>N</i> units) in the system. In addition, by knowing the average number of units in <i>M</i>/<i>M</i>/1/<i>N</i> queue, we can get the expected value of the treatment cells (servicing units number). Journal: Int. J. of Mathematics in Operational Research Pages: 490-499 Issue: 4 Volume: 19 Year: 2021 Keywords: statistical physics; tumour cells growth system; Poisson process; stochastic growth. File-URL: http://www.inderscience.com/link.php?id=117623 File-Format: text/html File-Restriction: Access to full text is restricted to subscribers. Handle: RePEc:ids:ijmore:v:19:y:2021:i:4:p:490-499 Template-Type: ReDIF-Article 1.0 Author-Name: V. Lavanya Author-X-Name-First: V. Author-X-Name-Last: Lavanya Author-Name: M. Sai Mohini Author-X-Name-First: M. Sai Author-X-Name-Last: Mohini Title: Malmquist Luenberger productivity index for microfinance productivity measurement Abstract: The objective of the study is to measure the microfinance institutions (MFIs) productivity by integrating the undesirable output, i.e., the non-performing loans (NPLs). We have calculated the productivity growth of MFIs over its two components, such as catch up effect and frontier shift effect by measuring the variation in efficiency and technology, respectively. The study is based on data of 72 Indian MFIs over five years from 2013-2017. We have employed a directional distance function (DDF) model to compute the Malmquist Luenberger productivity index (MLPI), output-oriented with undesirable output assuming a constant return to scale. The study also attempted to find a significant difference between two methodologies, i.e., Malmquist productivity index (MPI) and MLPI, to show the effect of NPL through testing of hypothesis. Furthermore we have classified the MFIs into four groups using a categorisation rule to infer the relationship between productivity growth, technical changes (TC), and efficiency change (EC) components to give noteworthy economic information for benchmarking and policymaking. The findings indicated that rather than the technological change component, the efficiency changes are contributing more to the productivity growth of MFIs. It implies that Indian MFIs need to strengthen more technically, to enhance their productivity and efficiency. Journal: Int. J. of Mathematics in Operational Research Pages: 456-489 Issue: 4 Volume: 19 Year: 2021 Keywords: microfinance; productivity growth; DEA; Malmquist Luenberger productivity index; MLPI; directional distance function; DDF; undesirable output. File-URL: http://www.inderscience.com/link.php?id=117625 File-Format: text/html File-Restriction: Access to full text is restricted to subscribers. Handle: RePEc:ids:ijmore:v:19:y:2021:i:4:p:456-489 Template-Type: ReDIF-Article 1.0 Author-Name: Andres P. Mendez Author-X-Name-First: Andres P. Author-X-Name-Last: Mendez Author-Name: Javier Martínez-Gómez Author-X-Name-First: Javier Author-X-Name-Last: Martínez-Gómez Author-Name: Juan Francisco Nicolalde Author-X-Name-First: Juan Francisco Author-X-Name-Last: Nicolalde Title: Simulation of a phase change material for an automotive thermal insulation system Abstract: The temperature that a car can reach inside is between 25°C to 40°C in certain environmental circumstances, for this reason, studies have been carried out in the field of materials science that allows controlling the interior environment of a car. This study proposes the use of paraffin as PCM, which was chosen through multi-criteria given its melting point that is 37°C. The result of simulating this material as a heat insulator is that in a 50°C of incidence in the roof of a vehicle, the internal temperature of the part is kept in 20°C. Journal: Int. J. of Mathematics in Operational Research Pages: 437-455 Issue: 4 Volume: 19 Year: 2021 Keywords: automobile; simulation; thermal storage; phase change; alternative materials; comparison; thermal insulation; energy; heat. File-URL: http://www.inderscience.com/link.php?id=117626 File-Format: text/html File-Restriction: Access to full text is restricted to subscribers. Handle: RePEc:ids:ijmore:v:19:y:2021:i:4:p:437-455 Template-Type: ReDIF-Article 1.0 Author-Name: R.H. Waliv Author-X-Name-First: R.H. Author-X-Name-Last: Waliv Title: Optimising a fuzzy multi-objective inventory model under different solution method Abstract: A multi-objective, multi-item fuzzy inventory model is constructed for deteriorating items under limited storage space as well as a budget constraint. The demand function is considered to be an increasing exponential time function. This study integrates fuzzy nonlinear programming (FNLP) and intuitionistic fuzzy optimisation (IFO) techniques. The objective of this work is to use FNLP and IFO techniques for multi-item, multi-objective fuzzy inventory model and to compare these techniques through numerical analysis. This work is also intended to find the optimal quantity to be replenished and identify the time point when shortages occurred. Another objective is to determine which method either FNLP or IFO gives efficient compromise solutions. In the case of IFO profit is observed more in the case with the membership function represented by linear than membership function represented by an exponential membership function. FNLP method with linear membership gives better results for maximising profit as compared to exponential membership function. FNLP works better than IFO in case of minimising shortage cost. The results along with the relation of profit and shortage cost with budget, warehouse space are studied through sensitivity analysis. Journal: Int. J. of Mathematics in Operational Research Pages: 247-268 Issue: 2 Volume: 19 Year: 2021 Keywords: fuzzy nonlinear programming; intuitionistic fuzzy optimisation; IFO; multi-objective inventory model; fuzzy multi-objective inventory model. File-URL: http://www.inderscience.com/link.php?id=116347 File-Format: text/html File-Restriction: Access to full text is restricted to subscribers. Handle: RePEc:ids:ijmore:v:19:y:2021:i:2:p:247-268 Template-Type: ReDIF-Article 1.0 Author-Name: Felipe S. Torres Author-X-Name-First: Felipe S. Author-X-Name-Last: Torres Author-Name: Javier Martínez-Gómez Author-X-Name-First: Javier Author-X-Name-Last: Martínez-Gómez Author-Name: Marcelo Moya Author-X-Name-First: Marcelo Author-X-Name-Last: Moya Author-Name: Ricardo A. Narvaez C. Author-X-Name-First: Ricardo A. Narvaez Author-X-Name-Last: C. Title: Characterisation and simulation of polymer membrane and PVC HDPE to use in an automotive application Abstract: The work aims to determine the necessary characteristics of the polymer membrane and PVC HDPE, which include good thermal, physical properties low cost, high weatherability and simulated for automotive application. The results obtained from two PVC and HDPE membranes in two different thicknesses are compared, considering controllable variables such as tension, elongation at break, working temperature and others. These tests are subject to ASTM standards which are collated to determine the membrane with better properties. The simulation was performed in software appropriate for calculating the polymer membrane to determine the stress, displacement and the safety factor of the membrane. HDPE membranes are superior to ABS and other membranes. At the same time help standards and design manual geosynthetics helped validate and determine that the geomembrane can be used in the automotive industry. Journal: Int. J. of Mathematics in Operational Research Pages: 417-436 Issue: 4 Volume: 19 Year: 2021 Keywords: simulation; geomembranes; safety; mechanical characterisation. File-URL: http://www.inderscience.com/link.php?id=117627 File-Format: text/html File-Restriction: Access to full text is restricted to subscribers. Handle: RePEc:ids:ijmore:v:19:y:2021:i:4:p:417-436 Template-Type: ReDIF-Article 1.0 Author-Name: Taufik Hidayat Author-X-Name-First: Taufik Author-X-Name-Last: Hidayat Author-Name: Rahutomo Mahardiko Author-X-Name-First: Rahutomo Author-X-Name-Last: Mahardiko Title: A mathematical model to forecast future banking income Abstract: The positive growth of operating income before pandemic of covid-19 had been felt by banking industry. The data shows that the pandemic of covid-19 changes the world condition especially the industry. This paper presents a mathematical model on recent data of bank revenue, the number of transactions and the information technology (IT) investment and forecasts future banking revenue, the number of transactions and IT investment for the next few years. The results show that, while there are problems faced in banking industry, the revenue, the number of transactions and the IT investment are significantly increasing. This mathematical model can be used for other industry. Journal: Int. J. of Mathematics in Operational Research Pages: 515-529 Issue: 4 Volume: 19 Year: 2021 Keywords: banking; covid-19; future forecast; Markov chain analysis. File-URL: http://www.inderscience.com/link.php?id=117628 File-Format: text/html File-Restriction: Access to full text is restricted to subscribers. Handle: RePEc:ids:ijmore:v:19:y:2021:i:4:p:515-529 Template-Type: ReDIF-Article 1.0 Author-Name: Ibrahim Yusuf Author-X-Name-First: Ibrahim Author-X-Name-Last: Yusuf Author-Name: Ismail Muhammad Musa Author-X-Name-First: Ismail Muhammad Author-X-Name-Last: Musa Title: Availability analysis of a complex system consisting of two subsystems in parallel configuration with replacement at failure Abstract: In this paper, investigation of the profit of parallel system consisting of two subsystems A and B is carried out. Each of the subsystem consists of two dissimilar components in active parallel. Two different replacement models are considered. Model 1 addresses the availability of the system by considering group replacement of the two subsystems at the system failure. Model 2 addresses the availability of the system by considering individual replacement of subsystem at its failure. In order to examine the validity of the models introduced and conduct sensitivity analysis, some diagrams are drawn for each model. Through the linear differential difference equation, explicit expressions for steady state availability for the two models are derived. Numerical examples are presented to illustrate the obtained results and to analyse the effect of group and individual replacement on the availability. Journal: Int. J. of Mathematics in Operational Research Pages: 530-550 Issue: 4 Volume: 19 Year: 2021 Keywords: availability; parallel; model; configuration; group replacement; individual replacement subsystem; complex system. File-URL: http://www.inderscience.com/link.php?id=117629 File-Format: text/html File-Restriction: Access to full text is restricted to subscribers. Handle: RePEc:ids:ijmore:v:19:y:2021:i:4:p:530-550 Template-Type: ReDIF-Article 1.0 Author-Name: Debasis Sharma Author-X-Name-First: Debasis Author-X-Name-Last: Sharma Author-Name: Sanjaya Kumar Parhi Author-X-Name-First: Sanjaya Kumar Author-X-Name-Last: Parhi Title: Local convergence of two Newton-like methods under Hölder continuity condition in Banach spaces Abstract: The main objective of this paper is to study the local convergence analysis of two cubically convergent Newton-like methods, harmonic mean Newton's method (HNM) and midpoint Newton's method (MNM), for approximating a unique solution of a nonlinear operator equation in Banach spaces. Unlike the earlier works using hypotheses up to the third-order Fréchet-derivative, we provide the convergence analysis using the only assumption that the first-order Fréchet derivative is Hölder continuous. Therefore, this study not only boosts the applicability of these schemes but also offers the convergence radii of these methods. Furthermore, the uniqueness of the solution and the error estimates are discussed. Finally, various numerical examples are provided to show that our study is applicable to solve such problems where earlier studies fail. Journal: Int. J. of Mathematics in Operational Research Pages: 500-514 Issue: 4 Volume: 19 Year: 2021 Keywords: Banach space; Hölder continuity; local convergence; harmonic mean Newton's method; HNM; midpoint Newton's method; MNM. File-URL: http://www.inderscience.com/link.php?id=117630 File-Format: text/html File-Restriction: Access to full text is restricted to subscribers. Handle: RePEc:ids:ijmore:v:19:y:2021:i:4:p:500-514 Template-Type: ReDIF-Article 1.0 Author-Name: Zineb Dahmane Author-X-Name-First: Zineb Author-X-Name-Last: Dahmane Author-Name: Amar Aissani Author-X-Name-First: Amar Author-X-Name-Last: Aissani Title: Optimal routing control of a retrial queue with two-phase service Abstract: Consider the problem of dynamic routing control in a retrial queue with a single server that provides two phases of service. All arriving customers join an ordinary queue and wait to be served. Every customer must receive service in both phases before leaving the system. After completion of the first phase, the server can either continue with the second phase for the same customer or stop the current service sequence in the first phase (to support a new customer that is on hold). In the latter case, the customer is placed in the retrial box, from where he is recalled for the second phase before leaving the system. Using Markov decision theory, we prove that an optimal policy exists that minimises the expected waiting cost for the system. We show that such a policy can be described by a switching curve that divides the state space into two contiguous regions. We present two conjectures regarding the structure of this policy, taking into account two different retrial policies. Journal: Int. J. of Mathematics in Operational Research Pages: 20-40 Issue: 1 Volume: 20 Year: 2021 Keywords: dynamic routing? two-phase service? ordinary queue? retrial box? Markov decision theory? threshold policy? classical retrial? constant retrial. File-URL: http://www.inderscience.com/link.php?id=117631 File-Format: text/html File-Restriction: Access to full text is restricted to subscribers. Handle: RePEc:ids:ijmore:v:20:y:2021:i:1:p:20-40 Template-Type: ReDIF-Article 1.0 Author-Name: R. Sivasamy Author-X-Name-First: R. Author-X-Name-Last: Sivasamy Author-Name: Peter O. Peter Author-X-Name-First: Peter O. Author-X-Name-Last: Peter Title: A c-server Poisson queue with customer impatience due to a slow-phase service Abstract: In this paper, we investigate a queue with <i>c</i>-servers in a Markovian environment (ME) under two phases (<i>S</i> - slow and <i>F</i> - fast). We assume that the sojourn times follow an exponential distribution at states <i>S</i> and <i>F</i> with parameters <i>ν</i> and <i>η</i> respectively. Each customer chooses a random relative deadline duration (RDD), which follows an exponential law with parameter <i>α</i> under <i>S</i>-phase but abandons the system as soon as its RDD expires and never returns. When the environment remains under phase <i>j</i> (= <i>S</i>, <i>F</i>), customers arrive according to a Poisson process with rate <i>λ<SUB align="right"><SMALL>j</SMALL></SUB></i>, and are served according to an exponential distribution with rate <i>μ<SUB align="right"><SMALL>j</SMALL></SUB></i> where <i>μ<SUB align="right"><SMALL>S</SMALL></SUB></i> < <i>μ<SUB align="right"><SMALL>F</SMALL></SUB></i>. We formulate the queue length process <i>Y</i><SUB align="right"><SMALL>(<i>j</i>,<i>n</i>)</SMALL></SUB>(<i>t</i>), representing the number of customers <i>n</i>(<i>t</i>), waiting in the phase <i>j</i> at time <i>t</i> as level dependent quasi birth-death (LDQBD) process in a 2-dimensional space. We apply matrix analytic methods on computational procedures and iterative methods to obtain scalar types of explicit expressions for the stationary probability distributions of <i>Y</i><SUB align="right"><SMALL>(<i>j</i>,<i>n</i>)</SMALL></SUB>(<i>t</i>) as <i>t</i> tends to infinity. We present comparable charts to highlight the variations between the steady state measures of an <i>M</i>(<i>λ</i><SUB align="right"><SMALL>0</SMALL></SUB>)/<i>M</i>(<i>μ</i><SUB align="right"><SMALL>0</SMALL></SUB> + <i>α</i>)/<i>c</i> queue with customer impatience (CI) and of another <i>M</i>(<i>λ</i>)/<i>M</i>(<i>μ</i>)/<i>c</i> facility without CI. Journal: Int. J. of Mathematics in Operational Research Pages: 85-98 Issue: 1 Volume: 20 Year: 2021 Keywords: two-phase service? fast-service? slow-service? stationary? probability distribution. File-URL: http://www.inderscience.com/link.php?id=117632 File-Format: text/html File-Restriction: Access to full text is restricted to subscribers. Handle: RePEc:ids:ijmore:v:20:y:2021:i:1:p:85-98 Template-Type: ReDIF-Article 1.0 Author-Name: Ajoy Hatibaruah Author-X-Name-First: Ajoy Author-X-Name-Last: Hatibaruah Author-Name: Sumit Saha Author-X-Name-First: Sumit Author-X-Name-Last: Saha Title: An inventory model for ameliorating and deteriorating items with stock and price dependent demand and time dependent holding cost with preservation technology investment Abstract: An inventory model is developed for ameliorating and deteriorating items considering stock and price dependent demand with completely backlogged shortages. Fast growing animals such as chicken, duck, etc. when are small in size and stock are purchased and raised in the farm. Stock and value of these items increases because of their high growth rate while stock may reduce due to death or other factors. Amelioration rate is assumed to follow Weibull distribution. Deterioration rate is considered to be constant and is controlled through an investment in preservation technology. The objective is to minimise the total cost per unit time and determine optimal selling price, preservation technology investment, time of occurrence of maximum inventory and shortage. To illustrate our model, some numerical examples are solved using an algorithm while convexity is shown graphically. Sensitivity analysis is performed to study the impact of variation of the parameters on optimal solution. Journal: Int. J. of Mathematics in Operational Research Pages: 99-122 Issue: 1 Volume: 20 Year: 2021 Keywords: amelioration? deterioration? preservation technology investment? stock and price dependent demand. File-URL: http://www.inderscience.com/link.php?id=117633 File-Format: text/html File-Restriction: Access to full text is restricted to subscribers. Handle: RePEc:ids:ijmore:v:20:y:2021:i:1:p:99-122 Template-Type: ReDIF-Article 1.0 Author-Name: A.S. Dibu Author-X-Name-First: A.S. Author-X-Name-Last: Dibu Author-Name: M.J. Jacob Author-X-Name-First: M.J. Author-X-Name-Last: Jacob Title: On the Gerber-Shiu function of a MAP risk model with possible delayed phase-type by-claims Abstract: This paper introduces the delayed claim settlement feature in a MAP risk model. Surplus process of the model incorporates two kinds of phase-type claims, the main claim and the by-claim. The delay feature is defined in such a way that every main claim may induce a by-claim with probability '<i>θ</i>' and payment of the by-claim is delayed until the next claim arrival. An appropriate Gerber-Shiu function under an auxiliary (delayed) timeline is assumed to analyse the Gerber-Shiu function under the primary (original) timeline. Transient analysis of the Markovian fluid flow models is tailored to develop defective renewal equations satisfying Gerber-Shiu functions. An explicit solution for renewal equations is derived in terms of the Lundberg roots. Further, a Neumann series solution is also provided. A numerical example on the moment of surplus before ruin in a two-state model. Journal: Int. J. of Mathematics in Operational Research Pages: 60-84 Issue: 1 Volume: 20 Year: 2021 Keywords: Gerber-Shiu function? MAP risk model? PH claims? delayed by-claims? system of Volterra integro-differential equation? matrix Lundberg equation. File-URL: http://www.inderscience.com/link.php?id=117634 File-Format: text/html File-Restriction: Access to full text is restricted to subscribers. Handle: RePEc:ids:ijmore:v:20:y:2021:i:1:p:60-84 Template-Type: ReDIF-Article 1.0 Author-Name: Rakhee Kulshrestha Author-X-Name-First: Rakhee Author-X-Name-Last: Kulshrestha Author-Name: Shruti Author-X-Name-First: Author-X-Name-Last: Shruti Title: Performance evaluation of call admission control based on signal quality in cellular mobile networks Abstract: The subscription of cellular networks is continuing to experience a growth at an unprecedented rate. It becomes a significant challenge for the cellular service provider to accommodate huge traffic demands while satisfying the desired quality of service (QoS) level perceived by the users. This paper proposes a new call admission control (CAC) scheme based on the quality of signals to support the guarantees of QoS. The proposed scheme also provides an algorithm to determine the optimal value of acceptance probability of new calls under the fractional guard channel (FGC) scheme which minimises the new call blocking probability. Moreover, there is a provision of finite buffer for handoff calls to further enhance the QoS of handoff users. Also, the paper includes numerical results to validate the effectiveness of the proposed scheme. Overall, this work provides an effective CAC model for optimising the performance of cellular networks. Journal: Int. J. of Mathematics in Operational Research Pages: 1-19 Issue: 1 Volume: 20 Year: 2021 Keywords: call admission control; CAC; fractional guard channel; FGC; signal quality; handoff; optimisation; Markov chain; cellular networks. File-URL: http://www.inderscience.com/link.php?id=117635 File-Format: text/html File-Restriction: Access to full text is restricted to subscribers. Handle: RePEc:ids:ijmore:v:20:y:2021:i:1:p:1-19 Template-Type: ReDIF-Article 1.0 Author-Name: S. Sindhuja Author-X-Name-First: S. Author-X-Name-Last: Sindhuja Author-Name: P. Arathi Author-X-Name-First: P. Author-X-Name-Last: Arathi Author-Name: Varun Mohan Author-X-Name-First: Varun Author-X-Name-Last: Mohan Title: A quadratic demand EOQ model for deteriorating items with time dependent shortage Abstract: In an inventory model, optimising the time and cost is a challenging task. This article focuses on an economic order quantity model (EOQ model) with a quadratic demand and constant deterioration of items. The aim of the paper is to provide a methodology to minimise the total cost in an EOQ model. This is achieved by increasing the deteriorating items, under the normal market conditions and considering the demand as a quadratic demand. Shortage in cost is similarly considered. A numerical example is discussed and compared with an existing model to illustrate the behaviour of the quadratic demand rate. There is a considerable reduction in total cost in the proposed model when compared with the existing model. Sensitivity analysis concerning the changes in parameters is carried out through the graphical representations. Complex algebraic equations are solved using MATLAB R2013a. Journal: Int. J. of Mathematics in Operational Research Pages: 41-59 Issue: 1 Volume: 20 Year: 2021 Keywords: economic order quantity model? quadratic demand rate? inventory? shortage? deterioration. File-URL: http://www.inderscience.com/link.php?id=117636 File-Format: text/html File-Restriction: Access to full text is restricted to subscribers. Handle: RePEc:ids:ijmore:v:20:y:2021:i:1:p:41-59 Template-Type: ReDIF-Article 1.0 Author-Name: Haimanti Pal Author-X-Name-First: Haimanti Author-X-Name-Last: Pal Author-Name: Sudarshan Bardhan Author-X-Name-First: Sudarshan Author-X-Name-Last: Bardhan Author-Name: Bibhas Chandra Giri Author-X-Name-First: Bibhas Chandra Author-X-Name-Last: Giri Title: Optimal production time and preservation technology investment for seasonal deteriorating products with a generalised ramp-type demand Abstract: A production-inventory model with price- and ramp-type time-dependent demand is developed in this paper. In view of the observation that the demand for a seasonal product initially increases with time and then becomes almost steady, and finally declines as time moves towards the end of the season, an EPQ model is considered with a generalised (two-parameter) ramp-type demand linearly dependent on sales price. The inventoried items are subject to continuous deterioration since production, and the rate of deterioration may be reduced by investing in preservation technology. The proposed model is developed under three different scenarios depending on the production time length. The optimal decisions, i.e., the optimal cycle length and preservation technology investment are obtained in each case. Certain conditions are derived to identify situations where the retailer should or should not invest in preservation technology. The proposed model is further illustrated numerically, and sensitivity analysis is carried out to investigate the impacts of key model-parameters on optimal decisions. Journal: Int. J. of Mathematics in Operational Research Pages: 123-148 Issue: 1 Volume: 20 Year: 2021 Keywords: economic production quantity? EPQ? generalised ramp-type demand? price-dependent demand? deterioration? preservation technology. File-URL: http://www.inderscience.com/link.php?id=117637 File-Format: text/html File-Restriction: Access to full text is restricted to subscribers. Handle: RePEc:ids:ijmore:v:20:y:2021:i:1:p:123-148 Template-Type: ReDIF-Article 1.0 Author-Name: Mehdi Safaei Author-X-Name-First: Mehdi Author-X-Name-Last: Safaei Author-Name: Meisam Nasrollahi Author-X-Name-First: Meisam Author-X-Name-Last: Nasrollahi Title: A multi-objective model to allocate multiple facilities at proposed locations in the multi-floor organisation, using an improved genetic algorithm. Case study: Isfahan Governorate Abstract: The impressive role in the proper design of facility layout on productivity cannot be simply overlooked. So far, many models of the genetic algorithm have been introduced to solve such problems. The common approach of all these methods is to eliminate unacceptable answers. But given that unacceptable responses also have positive characteristics that can have a positive effect on next-generation fitness, this positive character can be exploited. In the multi-objective and multi-scale model presented, graded punishment is intended for such solutions, but will benefit from their positive features. Finally, the effectiveness of this method was evaluated by studying a case study. The results confirm the model's ability to improve the existing conditions. The main application of this model, in multi-layered organizations, is the allocation of several facilities to one location, depending on its capacity. It is also used to design workshop facility layouts. Journal: Int. J. of Mathematics in Operational Research Pages: 126-144 Issue: 1 Volume: 18 Year: 2021 Keywords: genetic algorithm; basic layout model; fitness function; objective function; mutation; crossover. File-URL: http://www.inderscience.com/link.php?id=112269 File-Format: text/html File-Restriction: Access to full text is restricted to subscribers. Handle: RePEc:ids:ijmore:v:18:y:2021:i:1:p:126-144 Template-Type: ReDIF-Article 1.0 Author-Name: Minakshi Parida Author-X-Name-First: Minakshi Author-X-Name-Last: Parida Author-Name: Sunita Chand Author-X-Name-First: Sunita Author-X-Name-Last: Chand Title: Hermite Hadamard and Fejer type integral inequalities for harmonic convex (concave) fuzzy mappings Abstract: In this paper the Hermite Hadamard and Fejer type integral inequalities for harmonic convex (H-convex) and harmonic concave (H-concave) fuzzy mappings have been studied by using ranking value function. Furthermore, Hermite Hadamard inequality via Sugeno fuzzy integral has been given for H-concave fuzzy mappings. Moreover, the upper bound of the Sugeno fuzzy integral has been obtained for the H-concave fuzzy mapping by using ranking value function and the results have been justified with suitable examples. Journal: Int. J. of Mathematics in Operational Research Pages: 1-20 Issue: 1 Volume: 18 Year: 2021 Keywords: fuzzy numbers; H-convex (H-concave) fuzzy mappings; Hermite Hadamard inequality; Fejer type inequality; Sugeno fuzzy integral. File-URL: http://www.inderscience.com/link.php?id=112270 File-Format: text/html File-Restriction: Access to full text is restricted to subscribers. Handle: RePEc:ids:ijmore:v:18:y:2021:i:1:p:1-20 Template-Type: ReDIF-Article 1.0 Author-Name: S.K. Yadav Author-X-Name-First: S.K. Author-X-Name-Last: Yadav Author-Name: Cem Kadilar Author-X-Name-First: Cem Author-X-Name-Last: Kadilar Author-Name: Dinesh K. Sharma Author-X-Name-First: Dinesh K. Author-X-Name-Last: Sharma Title: New family of estimators for population mean using regression-cum-ratio exponential estimators Abstract: Sampling is inevitable whenever the population is vast, and one estimates the population mean rather than to calculate it. This article improves the estimation for the population mean of the primary variable through a new ratio-cum-exponential ratio family of estimators. The estimation properties, mainly bias and mean squared errors (MSE), are studied up to an approximation of order one for the suggested family. We make a comparison of the suggested family of estimators with the existing competing estimators of the population mean of the main variable in theory. In this way, the efficiency conditions for the suggested family are obtained. These conditions are satisfied in practice using the numerical example. Journal: Int. J. of Mathematics in Operational Research Pages: 85-114 Issue: 1 Volume: 18 Year: 2021 Keywords: main variable; supplementary variable; ratio-cum-exponential estimators; bias; mean squared errors; MSE; efficiency. File-URL: http://www.inderscience.com/link.php?id=112271 File-Format: text/html File-Restriction: Access to full text is restricted to subscribers. Handle: RePEc:ids:ijmore:v:18:y:2021:i:1:p:85-114 Template-Type: ReDIF-Article 1.0 Author-Name: Gregory Gurevich Author-X-Name-First: Gregory Author-X-Name-Last: Gurevich Author-Name: Baruch Keren Author-X-Name-First: Baruch Author-X-Name-Last: Keren Author-Name: Zohar Laslo Author-X-Name-First: Zohar Author-X-Name-Last: Laslo Title: Activity couple with interdependent durations: serial, parallel or partly overlapping scheduling? Abstract: This paper explores a problem of a hammock (sub-project) with two remaining activities, both eligible for execution. The activities can be scheduled in a serial mode, a parallel mode, or a partly overlapping mode. Each activity has alternative execution-modes that are related to the amount of budget allocated. We assume an interdependency between the activity time-cost trade-offs functions that are defined differently if the activities are scheduled separately, or if their schedule is overlapping. The aim is to determine, in the context of different objective functions and budget constraints, the optimal scheduling of the activities, with the appropriate allocation of budget to the activities. The paper presents a deterministic time-cost trade-offs model that takes into account the interdependency between the activity durations and enables decision makers to meet the above aim. Extension of the model and the analysis for the case where the activity durations are stochastic, are also examined. The paper reveals that when activity durations are stochastic, the optimal scheduling can be completely different from that of the deterministic case. Theoretical analysis and a case study provide numeric results that illustrate the difference between the deterministic and the stochastic solutions. Journal: Int. J. of Mathematics in Operational Research Pages: 45-70 Issue: 1 Volume: 18 Year: 2021 Keywords: project schedule; overlapping; time-cost trade-off; duration interdependencies; stochastic durations. File-URL: http://www.inderscience.com/link.php?id=112273 File-Format: text/html File-Restriction: Access to full text is restricted to subscribers. Handle: RePEc:ids:ijmore:v:18:y:2021:i:1:p:45-70 Template-Type: ReDIF-Article 1.0 Author-Name: Sameer Sharma Author-X-Name-First: Sameer Author-X-Name-Last: Sharma Author-Name: Mehak Chadha Author-X-Name-First: Mehak Author-X-Name-Last: Chadha Author-Name: Harpreet Kaur Author-X-Name-First: Harpreet Author-X-Name-Last: Kaur Title: Multi-step crossover genetic algorithm for bi-criteria parallel machine scheduling problems Abstract: This paper propounds the bi-criteria scheduling problem with identical parallel machines, volatile due dates and processing times. A robust and simple structured nature inspired approach has been applied for minimisation of maximum tardiness as the primary and the number of tardy jobs as the secondary criteria. The optimal values of both criteria are evaluated on the trot confined with a constraint that optimal value of secondary criteria does not infringe the primary criteria in the opposite sense of the requirement. To unfold such kind of NP hard optimisation problems, genetic algorithm (GA) has shown a great advantage in solving the combinatorial optimisation problems in view of its characteristic that has high efficiency and is the best fit for practical application. In this paper, a multi-step crossover fusion operator of genetic algorithms (MSXF) has been introduced and applied to a set of randomly generated problems of different sizes. The results obtained are correlated with the other crossover operators. Computational results show that MSXF operator outperforms all the most every time on randomly generated problems analogous to the parameter under consideration. Journal: Int. J. of Mathematics in Operational Research Pages: 71-84 Issue: 1 Volume: 18 Year: 2021 Keywords: bi-criteria; scheduling; tardiness; due dates; genetic algorithm. File-URL: http://www.inderscience.com/link.php?id=112275 File-Format: text/html File-Restriction: Access to full text is restricted to subscribers. Handle: RePEc:ids:ijmore:v:18:y:2021:i:1:p:71-84 Template-Type: ReDIF-Article 1.0 Author-Name: Nemat Allah Taghi-Nezhad Author-X-Name-First: Nemat Allah Author-X-Name-Last: Taghi-Nezhad Author-Name: Sadjad Moradi Author-X-Name-First: Sadjad Author-X-Name-Last: Moradi Author-Name: Gholamreza Karamali Author-X-Name-First: Gholamreza Author-X-Name-Last: Karamali Title: Fuzzy facility location problem with point and rectangular destinations Abstract: Facility location problem with point and area destinations is a special kinds of location problems in which, some demand centres considered as areas. Based on our knowledge, this issue has not been addressed in fuzzy literature and we have tried to investigate this issue in fuzzy environment. For this purpose, all customer demands are considered as fuzzy numbers, and the distances between points and destinations are calculated by <i>L</i><SUB align="right"><SMALL>1</SMALL></SUB> norm. To solve this fuzzy problem, three fuzzy theorems are proved which show that the objective function is separable, convex and piecewise continuous. Then, by using these fuzzy theorems, two fuzzy algorithms named fuzzy critical point algorithm and fuzzy weighting average algorithm are presented to obtain the best place for locating the facility centre. These two algorithms are based on piecewise differentiability of objective function and weighted average property, respectively. Finally, the applicability of our two presented algorithms is demonstrated by solving some numerical examples. Journal: Int. J. of Mathematics in Operational Research Pages: 21-44 Issue: 1 Volume: 18 Year: 2021 Keywords: fuzzy number; location problem; continues location problem; rectangular destinations; fuzzy weights. File-URL: http://www.inderscience.com/link.php?id=112288 File-Format: text/html File-Restriction: Access to full text is restricted to subscribers. Handle: RePEc:ids:ijmore:v:18:y:2021:i:1:p:21-44 Template-Type: ReDIF-Article 1.0 Author-Name: S.P. Singh Author-X-Name-First: S.P. Author-X-Name-Last: Singh Author-Name: Varsha Singh Author-X-Name-First: Varsha Author-X-Name-Last: Singh Author-Name: V.P. Singh Author-X-Name-First: V.P. Author-X-Name-Last: Singh Title: Symbiotic organisms search algorithm based model reduction of higher order continuous systems Abstract: This contribution proposes an approximation technique for reduction of higher order continuous systems (HOCS) using symbiotic organisms search (SOS) algorithm. The parameters of reduced-order model (ROM) of HOCS are obtained by minimising the normalised errors in between the Markov parameters and time moments of ROM and HOCS. The proposed technique always generates stable ROM for stable HOCS. Hurwitz criterion is utilised for ensuring the stability of ROM. The SOS algorithm is used for finding the ROM due to being simple and being free from algorithm-specific parameters. The effectiveness of proposed method is illustrated with the help of one test system. A comparative study is also accomplished for the results obtained using SOS algorithm and other optimisation techniques. The analysis indicates that the SOS algorithm outperforms when compared to other algorithms. Journal: Int. J. of Mathematics in Operational Research Pages: 115-125 Issue: 1 Volume: 18 Year: 2021 Keywords: model reduction; optimisation; Padé method; Routh approximation; symbiotic organisms search; SOS. File-URL: http://www.inderscience.com/link.php?id=112289 File-Format: text/html File-Restriction: Access to full text is restricted to subscribers. Handle: RePEc:ids:ijmore:v:18:y:2021:i:1:p:115-125 Template-Type: ReDIF-Article 1.0 Author-Name: Tuhin Bera Author-X-Name-First: Tuhin Author-X-Name-Last: Bera Author-Name: Nirmal Kumar Mahapatra Author-X-Name-First: Nirmal Kumar Author-X-Name-Last: Mahapatra Title: On solving linear programming problem by duality approach in neutrosophic environment Abstract: This paper extends the concept of crisp linear programming problem (<i>lpp</i>) by adopting the coefficients in objective function, technical coefficients, the right hand side coefficients and the decision variables as single valued triangular neutrosophic numbers (<i>S<SUB align="right"><SMALL>υt<SUB align="right"><SMALL>r</SMALL></SUB>n</SMALL></SUB></i> number). It is a special type of neutrosophic set. This modified concept is here called neutrosophic linear programming problem (<i>N<SUB align="right"><SMALL>lp</SMALL></SUB></i> problem). To develop this notion, a linear ranking function is newly constructed from geometrical concept first. Then the validity of existing crisp results are tested with the help of that ranking function in this new arena. An attempt is also taken to solve an <i>N<SUB align="right"><SMALL>lp</SMALL></SUB></i> problem by duality approach. For that, an efficient solution algorithm is developed by obeying the properties of ranking function. Finally, this proposed algorithm is demonstrated to solve a real life problem and some special cases are also illustrated by numerical examples. Journal: Int. J. of Mathematics in Operational Research Pages: 310-335 Issue: 3 Volume: 18 Year: 2021 Keywords: neutrosophic set; single valued triangular neutrosophic number; neutrosophic linear programming problem; duality. File-URL: http://www.inderscience.com/link.php?id=113576 File-Format: text/html File-Restriction: Access to full text is restricted to subscribers. Handle: RePEc:ids:ijmore:v:18:y:2021:i:3:p:310-335 Template-Type: ReDIF-Article 1.0 Author-Name: Aphisak Witthayapraphakorn Author-X-Name-First: Aphisak Author-X-Name-Last: Witthayapraphakorn Author-Name: Sasarose Jaijit Author-X-Name-First: Sasarose Author-X-Name-Last: Jaijit Author-Name: Peerayuth Charnsethikul Author-X-Name-First: Peerayuth Author-X-Name-Last: Charnsethikul Title: Solving the one-dimensional cutting stock problem under discrete, uncertain, time-varying demands using a hybrid of special-purpose Benders' decomposition and column generation Abstract: This study shows the integration of Benders' decomposition, column generation, and a special-purpose algorithm for solving the one-dimensional cutting stock problem under discrete, uncertain, time-varying demands. The results show that there is a linear relationship between the processing time and the number of scenarios involved in the raw material cutting patterns. Moreover, the algorithm results are not different from using column generation. During the search for production patterns, the quality of the solutions relies on the convergence tolerance. As the tolerance approaches zero, the solutions become near-optimal, but the computational time increases substantially. In addition, the experimental results indicate that the proposed method is suitable for large-scale problems. Journal: Int. J. of Mathematics in Operational Research Pages: 360-383 Issue: 3 Volume: 18 Year: 2021 Keywords: stochastic linear programming; one-dimensional cutting stock problem; uncertain demands; large-scale linear programming; Benders' decomposition. File-URL: http://www.inderscience.com/link.php?id=113578 File-Format: text/html File-Restriction: Access to full text is restricted to subscribers. Handle: RePEc:ids:ijmore:v:18:y:2021:i:3:p:360-383 Template-Type: ReDIF-Article 1.0 Author-Name: Rajesh Kumar Author-X-Name-First: Rajesh Author-X-Name-Last: Kumar Author-Name: Souvik Ghosh Author-X-Name-First: Souvik Author-X-Name-Last: Ghosh Author-Name: Abhijit Datta Banik Author-X-Name-First: Abhijit Datta Author-X-Name-Last: Banik Title: Numerical study on transient behaviour of finite bulk arrival or service queues with multiple working vacations Abstract: The transient behaviour of single server bulk queues with finite-buffer capacity is discussed numerically under the assumption that the server may take multiple working vacations after completing a busy period. It is considered that the inter-arrival and the service times are exponentially distributed and independent of each other. The buffer space is limited, therefore partial and full batch rejection policies are studied for the bulk arrival queueing model. However, for the batch service, the general bulk service rule is considered. Using probabilistic arguments and relating the state of the systems at two consecutive time epochs, differential equations are obtained to model such phenomena. Further, these equations are solved numerically by Runge-Kutta method and the time dependent numerical solutions are compared with the exact stationary solutions. The blocking probability and the mean waiting time of the first, last and an arbitrary customer are also reviewed mathematically and computed numerically. Journal: Int. J. of Mathematics in Operational Research Pages: 384-403 Issue: 3 Volume: 18 Year: 2021 Keywords: queuing theory; batch arrival; bulk service; multiple working vacations; MWVs; transient solution; Runge-Kutta. File-URL: http://www.inderscience.com/link.php?id=113586 File-Format: text/html File-Restriction: Access to full text is restricted to subscribers. Handle: RePEc:ids:ijmore:v:18:y:2021:i:3:p:384-403 Template-Type: ReDIF-Article 1.0 Author-Name: Arindam Garai Author-X-Name-First: Arindam Author-X-Name-Last: Garai Title: Fractile criterion iterative-interactive optimisation process for multi-objective stochastic linear programming problems in fuzzy environment Abstract: Present article focuses on one general fractile criterion iterative-interactive optimisation process in order to obtain the preferable Pareto optimal solution, subject to specified <i>main</i> objective function to multi-objective stochastic linear programming problems in fuzzy environment. This asks the managers to identify the <i>main</i> objective function among all objective functions without specifying any weights or utility functions. Unlike existing articles, the reference membership levels to conflicting objective functions are analytically determined by employing the trade-off ratios among objective functions in this process. Moreover, the necessity of only very few interactions with decision-makers saves the precious time and money of organisations. Numerical applications demonstrate the efficiency of proposed process. Finally, conclusions are drawn. Journal: Int. J. of Mathematics in Operational Research Pages: 289-309 Issue: 3 Volume: 18 Year: 2021 Keywords: fractile criterion optimisation; trade-off ratio; iterative-interactive optimisation; main objective function; multi-objective stochastic optimisation; chance constrained programming. File-URL: http://www.inderscience.com/link.php?id=113588 File-Format: text/html File-Restriction: Access to full text is restricted to subscribers. Handle: RePEc:ids:ijmore:v:18:y:2021:i:3:p:289-309 Template-Type: ReDIF-Article 1.0 Author-Name: Subhankar Adhikari Author-X-Name-First: Subhankar Author-X-Name-Last: Adhikari Author-Name: Brojeswar Pal Author-X-Name-First: Brojeswar Author-X-Name-Last: Pal Title: Random machine breakdown and stochastic corrective maintenance period on a production inventory system with safe period Abstract: This study deals with a production inventory model with random machine breakdown and corrective maintenance. Here the concept of the 'safe period' is introduced in which the machine is running uninterruptedly. 'Safe period' of the production system begins when production starts/commences either at the beginning of the inventory cycle or after corrective maintenance. When a mechanical breakdown occurs, it will be brought under corrective maintenance immediately. The period for corrective maintenance is also uncertain. As a result, shortages may occur. Here, a production system is adopted where a single machine is responsible for total production and all the produced items are good. The objective of this problem is to minimise the total expected cost per unit item because of how much amount is to be produced. An example is given to analyse the model numerically and sensitivity analysis also has been done for key parameters to test the feasibility of our model. Journal: Int. J. of Mathematics in Operational Research Pages: 404-432 Issue: 3 Volume: 18 Year: 2021 Keywords: production inventory; machine breakdown; corrective maintenance; safe period; backlogging. File-URL: http://www.inderscience.com/link.php?id=113590 File-Format: text/html File-Restriction: Access to full text is restricted to subscribers. Handle: RePEc:ids:ijmore:v:18:y:2021:i:3:p:404-432 Template-Type: ReDIF-Article 1.0 Author-Name: Reza Keykhaei Author-X-Name-First: Reza Author-X-Name-Last: Keykhaei Title: Multi-period mean-variance portfolio selection in a regime-switching market with a bankruptcy state and a state-dependent uncertain exit-time Abstract: In this paper, we study optimal multi-period portfolio selection problem with uncertain exit-time under mean-variance criterion in a Markovian regime-switching market. The market state space contains an absorbing state which represents the bankruptcy state. It is assumed that all random key parameters, i.e., asset returns, the recovery rate, and the exit-time depend on the current market state. Three common mean-variance formulations are considered, i.e., minimum variance formulation, maximum expected return formulation and the trade-off formulation. First, the problem with an uncertain exit-time is reformulated as a problem with a certain exit-time. Then, by applying the Lagrange duality method and the dynamic programming approach, the optimal multi-period portfolio strategies and the efficient frontier are derived in a closed form. Moreover, the conditions under which the aforementioned three problems are (mutually) equivalent are given. A numerical example is provided to illustrate the results. Journal: Int. J. of Mathematics in Operational Research Pages: 336-359 Issue: 3 Volume: 18 Year: 2021 Keywords: mean-variance portfolio selection; regime switching; bankruptcy state; state-dependent uncertain exit-time; dynamic programming. File-URL: http://www.inderscience.com/link.php?id=113591 File-Format: text/html File-Restriction: Access to full text is restricted to subscribers. Handle: RePEc:ids:ijmore:v:18:y:2021:i:3:p:336-359 Template-Type: ReDIF-Article 1.0 Author-Name: Anmar Abuhamdah Author-X-Name-First: Anmar Author-X-Name-Last: Abuhamdah Title: Adaptive black widow optimisation algorithm for data clustering Abstract: Generally, local search approaches are better than population-based approaches in exploiting the search space and worse for exploration. Recently, the black widow optimisation (BWO) algorithm was proposed for engineering optimisation problems as an algorithm balancing between the exploration and exploitation phases. However, the BWO algorithm employed three essential parameter rates, in which a different experiment is needed for each problem. The adaptive black widow optimisation (ABWO) algorithm is proposed to tune the parameters adaptively and accept worse solutions by relying on a local search, using the solutions' qualities average. Six medical datasets are used as a test domain with two calculations criteria to calculate the minimal distance. In order to evaluate the effectiveness of ABWO, a comparison is made between ABWO, BWO and other methods' performances that have been drawn from the acknowledged literature. Outcomes show ABWO is capable of obtaining better cluster qualities, thus outperforming many other methods. Journal: Int. J. of Mathematics in Operational Research Pages: 239-263 Issue: 2 Volume: 20 Year: 2021 Keywords: medical clustering problem; distance function; population-based algorithm; black widow optimisation algorithm; adaptive. File-URL: http://www.inderscience.com/link.php?id=118740 File-Format: text/html File-Restriction: Access to full text is restricted to subscribers. Handle: RePEc:ids:ijmore:v:20:y:2021:i:2:p:239-263 Template-Type: ReDIF-Article 1.0 Author-Name: Nabajyoti Bhattacharjee Author-X-Name-First: Nabajyoti Author-X-Name-Last: Bhattacharjee Author-Name: Nabendu Sen Author-X-Name-First: Nabendu Author-X-Name-Last: Sen Title: A multi-stage model to study inventory management of raw materials with shortages Abstract: The research on raw material procurement and maintenance in bio-ethanol production together with its socio-economic impact has been done. Most of the studies focus on sustainable utilisation and procurement policies of raw materials which includes transportations and maintenance of raw material inventory. In this present work we propose an interconnected multistage framework to minimise the cost involved in four stages of raw material procurement such as, purchase and transportation, primary storage without preservation, cleaning room and final storage with preservation. Further we establish that maintenance cost can be minimised by regulating the quantity of raw materials flowing from primary storage to final storage. We provide an algorithm to formulate a linear programming problem to optimise the cost involved in both purchase and transportation together. We perform sensitivity analysis to test flexibility of the model and represent the result graphically. Journal: Int. J. of Mathematics in Operational Research Pages: 207-238 Issue: 2 Volume: 20 Year: 2021 Keywords: multistage modelling; optimisation; raw material inventory; deterioration; waiting period; processing period; transportation problem; linear differential equation; linear programming problem; Hessian matrix. File-URL: http://www.inderscience.com/link.php?id=118743 File-Format: text/html File-Restriction: Access to full text is restricted to subscribers. Handle: RePEc:ids:ijmore:v:20:y:2021:i:2:p:207-238 Template-Type: ReDIF-Article 1.0 Author-Name: Biman Kanti Nath Author-X-Name-First: Biman Kanti Author-X-Name-Last: Nath Author-Name: Nabendu Sen Author-X-Name-First: Nabendu Author-X-Name-Last: Sen Title: A partially backlogged two-warehouse EOQ model with non-instantaneous deteriorating items, price and time dependent demand and preservation technology using interval number Abstract: In this paper, a two-warehouse EOQ model for non-instantaneous deteriorating item with price and time dependent demand is developed under imprecise environment. To reduce the loss due to deterioration, the concept of preservation technology investment is incorporated. In order to make the model more general, shortages are allowed and are partially backlogged. Further, the impreciseness of the parameters like coefficients of demand rate, holding costs, deterioration costs, shortage cost and lost sale cost are assumed as interval numbers which are made crisp by parametric functional form representation of interval numbers. The objective of this model is to find an optimal ordering policy with a view to minimise total average cost. To illustrate the developed model, a numerical example is taken in its support and also sensitivity analysis is carried out with respect to some important parameters. Journal: Int. J. of Mathematics in Operational Research Pages: 149-181 Issue: 2 Volume: 20 Year: 2021 Keywords: two-warehouse; non-instantaneous deteriorating item; preservation; partial backlogging; interval number; parametric functional form. File-URL: http://www.inderscience.com/link.php?id=118744 File-Format: text/html File-Restriction: Access to full text is restricted to subscribers. Handle: RePEc:ids:ijmore:v:20:y:2021:i:2:p:149-181 Template-Type: ReDIF-Article 1.0 Author-Name: Adeeba Umar Author-X-Name-First: Adeeba Author-X-Name-Last: Umar Author-Name: Ram Naresh Saraswat Author-X-Name-First: Ram Naresh Author-X-Name-Last: Saraswat Title: Neoteric divergence measure for refined interval-valued neutrosophic sets and its application in decision making Abstract: Smarandache originally initiated the theory of neutrosophic sets, which combined non-standard analysis and a tri-component set to handle indeterminate and inconsistent information. To deal with vagueness and uncertainty, the three functions which are truth membership function, indeterminacy membership function and falsity membership function play an important role and the sum of these three membership functions is less than three. This theory is used to depict information more appropriately. The prime aim of this paper is to introduce a novel divergence measure for refined interval-valued neutrosophic sets with the proof of its validity. Some other properties of the proposed divergence measure are given with their proofs. An application of novel divergence measure is shown with illustration for decision making in construction project selection in order to exhibit the legitimacy of the proposed method. The obtained results using the proposed model are compared with the results of existing methods and it was observed that proposed method gives better results for decision-making problems. Journal: Int. J. of Mathematics in Operational Research Pages: 182-206 Issue: 2 Volume: 20 Year: 2021 Keywords: divergence measure; neutrosophic sets; refined interval-valued neutrosophic sets; decision making. File-URL: http://www.inderscience.com/link.php?id=118745 File-Format: text/html File-Restriction: Access to full text is restricted to subscribers. Handle: RePEc:ids:ijmore:v:20:y:2021:i:2:p:182-206 Template-Type: ReDIF-Article 1.0 Author-Name: Ramiro Torres Author-X-Name-First: Ramiro Author-X-Name-Last: Torres Title: Line planning and passenger routing problem with application to the Quito transportation system Abstract: An important phase in the strategic planning process of a public transportation system is the line planning problem. It consists in determining a set of lines together with their frequencies such that a given transportation demand is satisfied. In this work an integer programming model for the integrated line planning and passenger routing problem is proposed. The model aims to improve the benefit and comfort of the passengers, namely maximising direct connection trips, and it also proposes to minimise the total cost for the operator. Restricted to linear transportation networks that are relevant for the Quito public transportation system, NP-hardness results and polynomial algorithms for special cases are presented. Performance of heuristic procedures for solving the integrated problem is evaluated over real-world and simulated instances. Journal: Int. J. of Mathematics in Operational Research Pages: 332-353 Issue: 3 Volume: 19 Year: 2021 Keywords: public transport optimisation; line planning problem; LPP passenger routing; computational complexity. File-URL: http://www.inderscience.com/link.php?id=116960 File-Format: text/html File-Restriction: Access to full text is restricted to subscribers. Handle: RePEc:ids:ijmore:v:19:y:2021:i:3:p:332-353 Template-Type: ReDIF-Article 1.0 Author-Name: Parakramaweera Sunil Dharmapala Author-X-Name-First: Parakramaweera Sunil Author-X-Name-Last: Dharmapala Title: Detecting outliers in DEA after correcting biases in efficiency scores using simulated beta samples Abstract: We address the issue that data used in DEA are possibly contaminated with statistical noise, and as a result, efficiency scores deviate from actual values due to statistical bias. In such situation, detecting outliers could be misleading. Therefore, we propose a method to correct the biases and compute DEA efficiency scores that follow underlying beta distributions, and we use Thompson et al.'s (1996) DEA model with assurance regions. Then, we demonstrate the bias-correction process of the DEA frontier estimates by constructing confidence intervals for the mean scores and use them to detect outliers. Journal: Int. J. of Mathematics in Operational Research Pages: 387-400 Issue: 3 Volume: 19 Year: 2021 Keywords: data envelopment analysis; DEA; assurance regions; order statistics; beta distribution; bias-correction; outliers. File-URL: http://www.inderscience.com/link.php?id=116961 File-Format: text/html File-Restriction: Access to full text is restricted to subscribers. Handle: RePEc:ids:ijmore:v:19:y:2021:i:3:p:387-400 Template-Type: ReDIF-Article 1.0 Author-Name: Abdelkader Mohamed Sghaier Derbali Author-X-Name-First: Abdelkader Mohamed Sghaier Author-X-Name-Last: Derbali Author-Name: Ali Lamouchi Author-X-Name-First: Ali Author-X-Name-Last: Lamouchi Title: Capital heterogeneity, entrepreneurship and two-way capital flows Abstract: This paper examines the drivers of two-way capital flow phenomenon in various developing countries where flows of portfolio investment and direct investment through borders prove contradictory directions. We try to claim that the scarcity of entrepreneurs in fewer developed countries, who improve firm productivity across unobservable (and thus not contractible) entrepreneurship effort, is an essential resource of two-way capital flows. Building upon the context of venture capital studies, this paper describes in a straightforward model that the lack of entrepreneurs would leave some domestic investment opportunities forgone, following in lower investment, lower interest rate, and lower savings compared optimality. Allowing foreign entrepreneurs to raise money from domestic financial market in the form of portfolio investment outflow and then to invest in the domestic firms in the form of direct investment inflow would help alleviate the situation. In this regard, two-way capital flows bring domestic economy benefit of learning through opening-up. Journal: Int. J. of Mathematics in Operational Research Pages: 375-386 Issue: 3 Volume: 19 Year: 2021 Keywords: entrepreneurship; two-way capital flows; portfolio investment; direct investment. File-URL: http://www.inderscience.com/link.php?id=116962 File-Format: text/html File-Restriction: Access to full text is restricted to subscribers. Handle: RePEc:ids:ijmore:v:19:y:2021:i:3:p:375-386 Template-Type: ReDIF-Article 1.0 Author-Name: Rajeev Prasad Author-X-Name-First: Rajeev Author-X-Name-Last: Prasad Author-Name: Sapan Kumar Das Author-X-Name-First: Sapan Kumar Author-X-Name-Last: Das Author-Name: Tarni Mandal Author-X-Name-First: Tarni Author-X-Name-Last: Mandal Author-Name: Jatindra Kumar Dash Author-X-Name-First: Jatindra Kumar Author-X-Name-Last: Dash Title: A modified ranking function of linear programming problem directly approach to fuzzy environment Abstract: This work introduced a modified ranking function which produced crisp linear programming (CLP) problems. A fully fuzzy linear programming (FFLP) problem in its balanced form having all the parameters and variables are triangular fuzzy numbers is taken into account during this study. Within the literature of the sector, the prevailing proposed approaches have many shortcomings, i.e., incorporate the rule of surplus variable and does not satisfy the constraints. Here, we bearing in mind of the prevailing shortcomings, a constructive solution is approached to beat the restrictions. For better exactness of the answer which is proposed by us, we use fuzzy number. Two numerical examples are illustrated and compared with the pre-existing methods. Journal: Int. J. of Mathematics in Operational Research Pages: 401-416 Issue: 3 Volume: 19 Year: 2021 Keywords: fully fuzzy linear programming; FFLP; fuzzy optimal solution; triangular fuzzy numbers; ranking function. File-URL: http://www.inderscience.com/link.php?id=116963 File-Format: text/html File-Restriction: Access to full text is restricted to subscribers. Handle: RePEc:ids:ijmore:v:19:y:2021:i:3:p:401-416 Template-Type: ReDIF-Article 1.0 Author-Name: Ritu Gupta Author-X-Name-First: Ritu Author-X-Name-Last: Gupta Author-Name: Divya Agarwal Author-X-Name-First: Divya Author-X-Name-Last: Agarwal Title: Cost analysis of N-policy vacation machine repair problem with optional repair Abstract: In this paper, we deal with the N-policy machine repairable system with warm spares and two repairmen under optional repair. The first repairman is always available to serve the failed units in the system while the second repairman leaves for a vacation of random length when the number of failed units is less than <i>N</i>. The second repairmen firstly performs essential repair to all failed units and then may provide second optional repair to some failed units which demand for it. We construct the system state governing equations and the system performance measures under transient condition which are examined by using a numerical approach based on Runge-Kutta method of the fourth order. Further, the sensitivity and cost analysis are facilitated to demonstrate the validity of the model by taking a numerical illustration. The effect of different parameters on system performance indices is demonstrated graphically. Journal: Int. J. of Mathematics in Operational Research Pages: 354-374 Issue: 3 Volume: 19 Year: 2021 Keywords: machine repair problem; warm spares; N-policy; first essential repair; FER; second optional repair; SOR; reliability; vacation; cost function; Markov process; Runge-Kutta method. File-URL: http://www.inderscience.com/link.php?id=116964 File-Format: text/html File-Restriction: Access to full text is restricted to subscribers. Handle: RePEc:ids:ijmore:v:19:y:2021:i:3:p:354-374 Template-Type: ReDIF-Article 1.0 Author-Name: Muhammad Al-Salamah Author-X-Name-First: Muhammad Author-X-Name-Last: Al-Salamah Title: Economic order quantity models for the remanufacturing industry with imperfect process, two-state Markovian and two types of inventory Abstract: An economic order quantity model for an imperfect manufacturing process and imperfect items is proposed. The remanufacturing industry converts used parts to aftermarket usable parts. The remanufacturing process is imperfect; a probability is known that an item after manufacturing is not repaired, and hence, this item is sent back to the inventory of damaged items for another round of remanufacturing. A discrete Markov chains model describes the transitional probabilities of the state of the item after the remanufacture. The first inventory model is proposed to identify the optimal order size of imperfect items, assuming the imperfect items arrive at a constant and finite rate. The second proposed model assumes an infinite arrival rate; hence, in essence imperfect items arrive in one batch. For both cases of the inventory models, the optimal economic order quantity is derived based on the expected average cost functions per time to the remanufacturer. Journal: Int. J. of Mathematics in Operational Research Pages: 85-103 Issue: 1 Volume: 19 Year: 2021 Keywords: economic order quantity; imperfect items; imperfect process; inventory; Markov chains. File-URL: http://www.inderscience.com/link.php?id=115429 File-Format: text/html File-Restriction: Access to full text is restricted to subscribers. Handle: RePEc:ids:ijmore:v:19:y:2021:i:1:p:85-103 Template-Type: ReDIF-Article 1.0 Author-Name: Nitin Panwar Author-X-Name-First: Nitin Author-X-Name-Last: Panwar Author-Name: Sanjeev Kumar Author-X-Name-First: Sanjeev Author-X-Name-Last: Kumar Title: Stochastic modelling and performance analysis of feeding unit in paper plant Abstract: In the present paper a probabilistic method for stochastic modelling and performance evaluation of a feeding unit is suggested. The paper plant consists of various units like feeding, pulping unit, bleaching unit, screening unit and paper production unit. Feeding unit is one of the paper plant's most significant functional units, consisting of three repairable subunits. Using Markov process, differential equations are created after drawing transition diagram and these models are then used to discover the feeding unit's availability by considering the repair and failure information acquired from maintenance personnel. Based upon the various performance values obtained for each subunit priority ranking is formulated for blower subunit. Journal: Int. J. of Mathematics in Operational Research Pages: 302-316 Issue: 3 Volume: 19 Year: 2021 Keywords: Markovian process; stochastic modelling; steady state availability; criticality analysis. File-URL: http://www.inderscience.com/link.php?id=116965 File-Format: text/html File-Restriction: Access to full text is restricted to subscribers. Handle: RePEc:ids:ijmore:v:19:y:2021:i:3:p:302-316 Template-Type: ReDIF-Article 1.0 Author-Name: Neelanjana Rajput Author-X-Name-First: Neelanjana Author-X-Name-Last: Rajput Author-Name: Anand Chauhan Author-X-Name-First: Anand Author-X-Name-Last: Chauhan Author-Name: R.K. Pandey Author-X-Name-First: R.K. Author-X-Name-Last: Pandey Title: EOQ model with a discount rate of inflation and optimisation with pentagonal fuzzy number Abstract: An EOQ model for deteriorating items under inflation over a finite time horizon is to be discussed here. This article derived a classical and fuzzy model for the effects of deterioration and inflation without any shortage. Due to uncertainty in parameters, we used a pentagonal fuzzy number and then optimise the total inventory cost. For the defuzzification of fuzzy total cost, we use two different methods namely the signed distance method and the graded mean integration method (GMI). Lastly, we discuss some numerical examples, comparative study along with graphical structures, and how this fuzzy model is more reliable for industries. Journal: Int. J. of Mathematics in Operational Research Pages: 264-280 Issue: 2 Volume: 20 Year: 2021 Keywords: fuzzy EOQ model; inflation; discount rate; deterioration; graded mean integration method; pentagonal fuzzy number; signed distance method. File-URL: http://www.inderscience.com/link.php?id=118757 File-Format: text/html File-Restriction: Access to full text is restricted to subscribers. Handle: RePEc:ids:ijmore:v:20:y:2021:i:2:p:264-280 Template-Type: ReDIF-Article 1.0 Author-Name: Bam Bahadur Sinha Author-X-Name-First: Bam Bahadur Author-X-Name-Last: Sinha Author-Name: R. Dhanalakshmi Author-X-Name-First: R. Author-X-Name-Last: Dhanalakshmi Title: An effective movie recommender system enhanced with time series analysis of user rating behaviour Abstract: Recommender system aims at improvising user satisfaction by taking decision on what movie or item to recommend next. Over time though, learners and learning behaviours shift regularly. This paper introduces a novel behaviour-inspired suggestion algorithm named the TimeFly-PPSE algorithm, which operates on the concept of changing user's motives around time. The suggested model takes temporal knowledge into account and monitors the progression of consumers and items that are useful in providing adequate recommendations. The latter outlines a framework that enrolls the user's shifting behaviour to include guidance for personalisation. TimeFly's findings are contrasted with those of other well-known algorithms. Simulation test on 100K MovieLens dataset shows that utilising TimeFly contributes to recommendations that are exceptionally efficient and reliable. Journal: Int. J. of Mathematics in Operational Research Pages: 317-331 Issue: 3 Volume: 19 Year: 2021 Keywords: recommendation; prediction; MovieLens; time-aware; genres; mean absolute error; MAE. File-URL: http://www.inderscience.com/link.php?id=116966 File-Format: text/html File-Restriction: Access to full text is restricted to subscribers. Handle: RePEc:ids:ijmore:v:19:y:2021:i:3:p:317-331 Template-Type: ReDIF-Article 1.0 Author-Name: S.K. Yadav Author-X-Name-First: S.K. Author-X-Name-Last: Yadav Author-Name: Dinesh K. Sharma Author-X-Name-First: Dinesh K. Author-X-Name-Last: Sharma Author-Name: Kate Brown Author-X-Name-First: Kate Author-X-Name-Last: Brown Title: New class of estimators for enhanced estimation of average production of peppermint yield utilising known auxiliary variable Abstract: The arithmetic mean is the best measure of central tendency for a homogenous population for the characteristics under study. Estimation can be improved by including auxiliary information and various estimators have been suggested in the literature. In this paper, a new class of estimators using known auxiliary parameters for estimation of the average yield of peppermint oil is suggested. The proposed estimator's sampling properties, the bias and mean squared error (MSE) up to the approximation of first order are studied. The suggested estimator is compared theoretically to some existing estimators of population mean that an auxiliary variable. The theoretical efficiency conditions are verified using real primary data collected from the Siddaur Block of Barabanki District at Uttar Pradesh State (India). The performances of various estimators are judged from their calculated MSEs using this primary data. Journal: Int. J. of Mathematics in Operational Research Pages: 281-295 Issue: 2 Volume: 20 Year: 2021 Keywords: primary variable; auxiliary variable; estimator; bias; mean squared error; MSE; PRE. File-URL: http://www.inderscience.com/link.php?id=118758 File-Format: text/html File-Restriction: Access to full text is restricted to subscribers. Handle: RePEc:ids:ijmore:v:20:y:2021:i:2:p:281-295 Template-Type: ReDIF-Article 1.0 Author-Name: Sandipa Bhattacharya Author-X-Name-First: Sandipa Author-X-Name-Last: Bhattacharya Author-Name: Seema Sarkar Mondal Author-X-Name-First: Seema Sarkar Author-X-Name-Last: Mondal Title: A seller-buyer supply chain model with fixed and variable labour capacity along with advertising cost and demand Abstract: In this paper, supply chain models of single seller and single buyer are proposed in crisp and fuzzy environment to maximise the profit under a manageable inventory policy. These models incorporate the advertising expenditure a part of which is shared by the seller to cooperate with the buyer to have a overall compromised gain of the entire chain. In this case shortages are not permitted so that the rate of production is always greater than or equal to the rate of demand. Keeping all these in view, cooperative and non-cooperative seller-buyer models are developed with fixed and variable labour capacity. The non-cooperative model is solved by seller-buyer Stackelberg strategy while the cooperative problem is solved for pareto optimal solution. Numerical examples are considered to verify the model and the nonlinear problem is solved using nonlinear optimisation technique. Journal: Int. J. of Mathematics in Operational Research Pages: 65-84 Issue: 1 Volume: 19 Year: 2021 Keywords: cooperative and non-cooperative seller-buyer model; fixed and variable labour capacity; advertisement cost sharing; crisp and fuzzy environment. File-URL: http://www.inderscience.com/link.php?id=115431 File-Format: text/html File-Restriction: Access to full text is restricted to subscribers. Handle: RePEc:ids:ijmore:v:19:y:2021:i:1:p:65-84 Template-Type: ReDIF-Article 1.0 Author-Name: Fouzia Ghellab Author-X-Name-First: Fouzia Author-X-Name-Last: Ghellab Author-Name: Mohand Ouamer Bibi Author-X-Name-First: Mohand Ouamer Author-X-Name-Last: Bibi Title: Optimality and suboptimality criteria in a quadratic problem of optimal control with a piecewise linear entry Abstract: In the present paper, we intend to minimise a terminal quadratic functional of optimal control with a piecewise linear entry and that by using a support concept. The latter is connected to the existence of a non-degenerate matrix used to calculate the Lagrange multiplier <i>y</i> and the conjugate function <i>Ψ</i> via a direct way, contrary to the traditional maximum principle. We prove the optimality criterion by means of the implicit functions theorem. Then, we reformulate it as a support maximum principle from which we derive a sufficient condition of suboptimality. The obtained results are illustrated by a numerical example on mechanics. Journal: Int. J. of Mathematics in Operational Research Pages: 1-18 Issue: 1 Volume: 19 Year: 2021 Keywords: optimality criterion; sufficient condition of suboptimality; quadratic optimal control problem; piecewise linear entry. File-URL: http://www.inderscience.com/link.php?id=115433 File-Format: text/html File-Restriction: Access to full text is restricted to subscribers. Handle: RePEc:ids:ijmore:v:19:y:2021:i:1:p:1-18 Template-Type: ReDIF-Article 1.0 Author-Name: A. Azhagappan Author-X-Name-First: A. Author-X-Name-Last: Azhagappan Author-Name: T. Deepa Author-X-Name-First: T. Author-X-Name-Last: Deepa Title: Transient behaviour of a Markovian vacation queue with re-service balking control of admission closedown and setup times Abstract: This paper studies an <i>M</i>/<i>M</i>/1 queueing model with single as well as multiple vacation, closedown, setup times, re-service, balking and control of admission. All the arriving customers are not allowed to join the queue all the time. They are either permitted to join the queue or rejected. Whenever the system becomes empty and the server resumes closedown work. If any customer joins the queue before the completion of closedown, the closedown work is interrupted and the server commences an exhaustive busy period. Otherwise, it starts the vacation after the completion of closedown period. During the vacation period, the permitted arrivals may join the queue or balk. At the moment of completion of vacation, the server begins the setup work before the commencement of service. After the service, each customer has the option to get immediate re-service. The transient and stationary system size probabilities are derived. The time-dependent mean and variance are also obtained. Numerical simulations are also presented. Journal: Int. J. of Mathematics in Operational Research Pages: 19-44 Issue: 1 Volume: 19 Year: 2021 Keywords: the M/M/1 queue; single and multiple vacations; closedown setup times and re-service; balking and admission control. File-URL: http://www.inderscience.com/link.php?id=115445 File-Format: text/html File-Restriction: Access to full text is restricted to subscribers. Handle: RePEc:ids:ijmore:v:19:y:2021:i:1:p:19-44 Template-Type: ReDIF-Article 1.0 Author-Name: G. Ayyappan Author-X-Name-First: G. Author-X-Name-Last: Ayyappan Author-Name: K. Thilagavathy Author-X-Name-First: K. Author-X-Name-Last: Thilagavathy Title: Analysis of MAP/PH/1 queueing model with immediate feedback, starting failures, single vacation, standby server, delayed repair, breakdown and impatient customers Abstract: We have analysed the queueing model with a single server in which customers arrive according to the Markovian arrival process, the service process according to phase type distributions and the standby server who is serving at a lower rate also follows the phase type distribution. The total number of customers are present in the system under the steady-state probability vector has been probed by using matrix-analytic method (MAM). We have examined the stability condition, the analysis of the busy period and derived some important performance measures of our model. Numerical results and graphical representation are discussed for the proposed model. Journal: Int. J. of Mathematics in Operational Research Pages: 269-301 Issue: 3 Volume: 19 Year: 2021 Keywords: Markovian arrival process; MAP; phase type distributions; immediate feedback; standby server; delay time to repair; single vacation. File-URL: http://www.inderscience.com/link.php?id=116981 File-Format: text/html File-Restriction: Access to full text is restricted to subscribers. Handle: RePEc:ids:ijmore:v:19:y:2021:i:3:p:269-301 Template-Type: ReDIF-Article 1.0 Author-Name: K. Senbagam Author-X-Name-First: K. Author-X-Name-Last: Senbagam Author-Name: M. Kokilamani Author-X-Name-First: M. Author-X-Name-Last: Kokilamani Title: Analysis of fuzzy inventory model for Gompertz deteriorating items with linear demand and shortages Abstract: This article establishes a fuzzy inventory model for Gompertz deteriorating items with linear demand and constant holding cost. Stock-out is permitted and completely back-ordered. The goal is to find the optimum cycle times to maximise the overall profit by using a graded mean representation method. In this study, we first developed an arithmetical model to find the most favourable solution. The solution process is also developed in order to maximise the total profit. The total profit is calculated on the basis of various principles. The deterioration cost, shortage cost, holding cost and demand rate are assumed as a heptagonal and octagonal fuzzy numbers. Some numerical examples are provided to support the solution procedure. Finally, a sensitivity analysis of some parameters and the conclusion of the proposed model will be discussed. Journal: Int. J. of Mathematics in Operational Research Pages: 104-128 Issue: 1 Volume: 19 Year: 2021 Keywords: inventory system; Gompertz deterioration; linear function; heptagonal fuzzy numbers; octagonal fuzzy numbers; graded mean representation method. File-URL: http://www.inderscience.com/link.php?id=115446 File-Format: text/html File-Restriction: Access to full text is restricted to subscribers. Handle: RePEc:ids:ijmore:v:19:y:2021:i:1:p:104-128 Template-Type: ReDIF-Article 1.0 Author-Name: Vijaya Laxmi Pikkala Author-X-Name-First: Vijaya Laxmi Author-X-Name-Last: Pikkala Author-Name: Girija Bhavani Edadasari Author-X-Name-First: Girija Bhavani Author-X-Name-Last: Edadasari Title: Variant working vacation Markovian queue with second optional service, unreliable server and retention of reneged customers Abstract: In this paper, a variant working vacation queueing system with second optional service, unreliable server, and retention of reneged customers is studied. This model has potential applications in tele-services, banks, manufacturing processes, etc. The expressions of the steady-state probabilities and the system sizes when the server is in different states are obtained using probability generating functions. This paper also discusses an optimisation problem under a given cost structure. Direct search method and quadratic fit search method (QFSM) are applied to obtain the optimum number of working vacations and optimum service rates during regular busy period and working vacation period, respectively. Journal: Int. J. of Mathematics in Operational Research Pages: 45-64 Issue: 1 Volume: 19 Year: 2021 Keywords: first essential service; FES; second optional service; SOS; working vacation; unreliable server; reneging; retention. File-URL: http://www.inderscience.com/link.php?id=115447 File-Format: text/html File-Restriction: Access to full text is restricted to subscribers. Handle: RePEc:ids:ijmore:v:19:y:2021:i:1:p:45-64