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Newsvendor problem with multiple unreliable suppliers

INTERNATIONAL JOURNAL OF PRODUCTION RESEARCH 2014年第1期52卷 221-242页

作者： Merzifonluoglu, Yasemin Feng, Yazhe Middle E Tech Univ Guzelyurt Turkey Virginia Tech Dept Ind & Syst Engn Blacksburg VA USA

This paper focuses on supplier-related decisions in a newsvendor setting. We build upon the current literature by analysing the newsvendor problem with multiple unreliable and non-identical suppliers. We also incorporate both fixed ordering costs and capacity limits for supplier selection. We develop an exact algorithm to solve the problem optimally and a heuristic algorithm to solve the problem efficiently. Through structural properties of the optimal solution and a numerical study, we provide useful managerial implications regarding optimal sourcing strategies in complex supply chains. Previous literature concludes that with multiple unreliable (independent) suppliers, cost is the order qualifier and reliability is the order winner. We found that when fixed ordering costs and supply capacities exist, this insight no longer holds. We also examine the sensitivity of the sourcing decisions to supplier capacity levels, demand uncertainty, salvage value and shortage cost. Our results show that high levels of demand uncertainty lead firms to turn to a single-sourcing strategy whereas high salvage values and high shortage cost suggest multi-sourcing strategy.

关键词： inventory branch and bound non-linear programming supply chain management

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A novel algorithm for solving optimal path planning problems based on parametrization method and fuzzy aggregation

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PHYSICS LETTERS A 2009年第38期373卷 3439-3449页

作者： Zamirian, M. Kamyad, A. V. Farahi, M. H. Ferdowsi Univ Mashhad Dept Math Mashhad 917751159 Iran

In this Letter a new approach for solving optimal path planning problems for a single rigid and free moving object in a two and three dimensional space in the presence of stationary or moving obstacles is presented. In this approach the path planning problems have some incompatible objectives such as the length of path that must be minimized, the distance between the path and obstacles that must be maximized and etc., then a multi-objective dynamic optimization problem (MODOP) is achieved. Considering the imprecise nature of decision maker's (DM) judgment, these multiple objectives are viewed as fuzzy variables. By determining intervals for the values of these fuzzy variables, flexible monotonic decreasing or increasing membership functions are determined as the degrees of satisfaction of these fuzzy variables on their intervals. Then, the optimal path planning policy is searched by maximizing the aggregated fuzzy decision values, resulting in a fuzzy multi-objective dynamic optimization problem (FMODOP). Using a suitable t-norm, the FMODOP is converted into a non-linear dynamic optimization problem (NLDOP). By using parametrization method and some calculations, the NLDOP is converted into the sequence of conventional non-linear programming problems (NLPP). It is proved that the solution of this sequence of the NLPPs tends to a Pareto optimal solution which, among other Pareto optimal solutions, has the best satisfaction of DM for the MODOP. Finally. the above procedure as a novel algorithm integrating parametrization method and fuzzy aggregation to solve the MODOP is proposed. Efficiency of our approach is confirmed by some numerical examples. (C) 2009 Elsevier B.V. All rights reserved.

关键词： Optimal path planning Multi-objective dynamic optimization Fuzzy aggregation Parametrization method non-linear programming Membership function

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Numerical solution of the time-delayed optimal control problems with hybrid functions

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IMA JOURNAL OF MATHEMATICAL CONTROL AND INFORMATION 2015年第3期32卷 623-638页

作者： Nazemi, Alireza Shabani, Mohammad Mehdi Shahrood Univ Sch Math Sci Dept Math Shahrood Iran

We consider an approximation scheme using hybrid functions for solving time-delayed optimal control problems with terminal inequality constraints. Using a Pade approximation, the problem is first transformed into one without a time-delayed argument. A computational method based on hybrid functions in time-domain is then proposed for solving the obtained non-delay optimal control problem. Hybrid functions integral operational matrix and direct collocation method are utilized to find the approximated optimal trajectory and the optimal control law of the original problem. Numerical results are also given to demonstrate the efficiency of the method.

关键词： time-delayed optimal control problems approximation terminal condition hybrid functions non-linear programming Bernoulli polynomials block-pulse

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Quasi-continuous dynamic equilibrium assignment with departure time choice in congested unidirectional pedestrian networks

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JOURNAL OF THE OPERATIONAL RESEARCH SOCIETY 2002年第1期53卷 97-107页

作者： Huang, HJ Lam, WHK Beijing Univ Aeronaut & Astronaut Sch Management Beijing 100083 Peoples R China Hong Kong Polytech Univ Hong Kong Hong Kong Peoples R China

Although walking has been considered as an important transport mode, pedestrian modelling has received little attention in either academic or practising circles. There is an increasing need for methods that can be used to help the planning, design and management of pedestrian traffic systems. This paper presents a nonlinear programming formulation of the dynamic pedestrian equilibrium assignment problem based on the following assumptions. The pedestrian traffic system in a congested urban area can be modelled as a capacitated network with alternative walkway sections. People in this pedestrian network make such decisions as selecting departure time and walking path between origins and destinations (OD). The study horizon is divided equally into shorter time intervals of 5-10 minutes each, for which the pedestrian departure time matrices are given by a logit formula. It is dependent on the predetermined departure time costs and the equilibrium OD walking costs. In the proposed model, a 'quasi-continuous' technique is adopted to smooth out the transitions of various variables between time intervals and to satisfy the first-in-first-out discipline. A heuristic algorithm that generates approximate solutions to the model is presented. The numerical results in a real network shows that the model and algorithm proposed in this paper are able to capture the main characteristics of the departure time and route choices in congested unidirectional pedestrian traffic systems.

关键词： transport non-linear programming pedestrian network dynamic equilibrium assignment logit-based departure time choice

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Multi-Objective Optimization of Energy-Efficient Buffer Allocation Problem for non-Homogeneous Unreliable Production Lines

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IEEE ACCESS 2022年 10卷 3320-3335页

作者： Alaouchiche, Yasmine Ouazene, Yassine Yalaoui, Farouk Univ Technol Troyes Comp Sci & Digital Soc Lab LIST3N F-10004 Troyes France

The current context of rising ecological awareness and high competitiveness, reveals a strong necessity to integrate the sustainability paradigm into the design of production systems. The buffer allocation problem is of particular interest since buffers absorb disruptions in the production line. However, despite the rich literature addressing the BAP, there are no studies that use a multi-objective framework to deal with energetic considerations. In this study, the energy-efficient buffer allocation problem (EE-BAP) is studied through a multi-objective resolution approach. The multi-objective problem is solved to optimize two conflicting objectives: maximizing production throughput and minimizing its energy consumption, under a total storage capacity available. The weighted sum and epsilon-constraint methods as well as the elitist non-dominated sorting genetic algorithm (NSGA- II) are adapted and implemented to solve the EE-BAP. The obtained solutions are analyzed and compared using different performance metrics. Numerical experiments show that epsilon-constraint outperforms the NSGA- II when considering comparable computational time. The Pareto solutions obtained are trade-offs between the two objectives, enabling decision making that balances productivity maximization with energy economics in the design of production lines.

关键词： Optimization Throughput Energy efficiency Resource management Energy consumption linear programming Production Buffer allocation problem energy efficiency multi-objective optimization unreliable production lines non-linear programming

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Impact of a price-maker pumped storage hydro unit on the integration of wind energy in power systems

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ENERGY 2014年 69卷 3-11页

作者： Sousa, Jorge A. M. Teixeira, Fabio Faias, Sergio ISEL Lisbon Engn Super Inst Dept Elect Engn & Automat P-1950062 Lisbon Portugal INESC ID Lisbon Portugal

The increasing integration of larger amounts of wind energy into power systems raises important operational issues, such as the balance between power generation and demand. The pumped storage hydro (PSH) units are one possible solution to mitigate this problem, once they can store the excess of energy in the periods of higher generation and lower demand. However, the behavior of a PSH unit may differ considerably from the expected in terms of wind power integration when it operates in a liberalized electricity market under a price-maker context. In this regard, this paper models and computes the optimal PSH weekly scheduling in a price-taker and price-maker scenarios, either when the PSH unit operates in standalone and integrated in a portfolio of other generation assets. Results show that the price-maker standalone PSH will integrate less wind power in comparison with the price-taker situation. Moreover, when the PSH unit is integrated in a portfolio with a base load power plant, the role of the price elasticity of demand may completely change the operational profile of the PSH unit. (C) 2014 Elsevier Ltd. All rights reserved.

关键词： Electricity markets Electricity systems modeling Pumped storage hydro scheduling Price-maker Wind power integration non-linear programming

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A decomposition approach for the fuel-constrained economic power-dispatch problem

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EUROPEAN JOURNAL OF OPERATIONAL RESEARCH 1999年第2期112卷 460-466页

作者： Takriti, S Krasenbrink, B IBM Corp Thomas J Watson Res Ctr Dept Math Sci Yorktown Heights NY 10598 USA

We consider a special class of non-convex programs that are encountered in dispatching the generating units of an electric company. The general form of these problems is {min c(T)x:l(j) less than or equal to A(j)x(j)less than or equal to u(j),x(j) greater than or equal to 0, Sigma(j=1)(m) x(i,t)(j) = f(i)(y(i,t)), By = d,y greater than or equal to 0}, where c greater than or equal to 0, all entries in A are non-negative, and f(i)(y(i,t))greater than or equal to 0. We show that one call achieve global optimality in the case of l(j) = 0. For the special case in which A(j) is a vector of ones, we suggest an alternative formulation in which the non-linearity is moved to the objective function. Numerical results indicate significant improvement in the number of iterations and computer time needed to solve the problem. (C) 1999 Elsevier Science B.V. All rights reserved.

关键词： decomposition techniques economic power dispatch non-linear programming

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An FPTAS for minimizing a class of low-rank quasi-concave functions over a convex set

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OPERATIONS RESEARCH LETTERS 2013年第2期41卷 191-196页

作者： Goyal, Vineet Ravi, R. Columbia Univ New York NY 10027 USA Carnegie Mellon Univ Tepper Sch Business Pittsburgh PA 15213 USA

We consider the problem of minimizing a class of quasi-concave functions over a convex set. Quasi-concave functions are generalizations of concave functions and NP-hard to minimize in general. We present a simple fully polynomial time approximation scheme (FPTAS) for minimizing a class of low-rank quasi-concave functions. Our algorithm solves a polynomial number of linear minimization problems and computes an extreme point near-optimal solution. Therefore, it applies directly to combinatorial 0-1 problems where the convex hull of feasible solutions is known. (C) 2013 Elsevier B.V. All rights reserved.

关键词： Quasi-concave programming non-linear programming non-convex programming Polynomial approximation schemes

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Power-aware scheduling of preemptable jobs on identical parallel processors to meet deadlines

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EUROPEAN JOURNAL OF OPERATIONAL RESEARCH 2012年第1期218卷 68-75页

作者： Rozycki, R. Weglarz, J. Poznan Univ Tech Inst Comp Sci PL-60965 Poznan Poland

This paper deals with a power-aware scheduling of preemptable independent jobs on identical parallel processors where ready time for each job is given and its completion time has to meet a given deadline. Jobs are described by (different) continuous, strictly concave functions relating their processing speeds at a time to the amount of power allotted at the moment. Power is a continuous, doubly constrained resource, i.e. both: its availability at each time instant and consumption over scheduling horizon are constrained. A methodology based on properties of minimum-length schedules is utilized to determine the existence of a feasible schedule for given amounts of energy and power. The question about minimum levels of power and energy ensuring the existence of a feasible schedule for a given set of jobs is also studied. (C) 2011 Elsevier B.V. All rights reserved.

关键词： Power-aware computing Preemptable jobs Ready times Deadlines non-linear programming

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An evolutionary strategic weight manipulation approach for multi-attribute decision making: TOPSIS method

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INTERNATIONAL JOURNAL OF APPROXIMATE REASONING 2021年 129卷 64-83页

作者： Dutta, Bapi Dao, Son Duy Martinez, Luis Goh, Mark Natl Univ Singapore Logist Inst Asia Pacific 21 Heng Mui Keng Terrace Singapore 119613 Singapore IMT Atlantique Brest France Univ Jaen Dept Comp Sci Jaen Spain

Weight information of the attributes plays a pivotal role in multi-attribute decision making (MADM) problems. Oftentimes, a decision maker may try to manipulate this weight information to persuade a particular rank order of the alternatives of his/her interest. In the literature, this type of manipulation is known as strategic manipulation of the weight information. In this study, we consider the manipulation of weight information strategically in a TOPSIS MADM method under two scenarios: (1) completely unknown weight information i.e. the decision maker does not provide any weight information;(2) incomplete weight information i.e. the decision maker provides only partial preference information over the attributes. This weight manipulation problem is formulated as a mixed integer non-linear programming (MINLP) problem which is highly constrained. Therefore, for solving the MINLP model, a genetic algorithm based solution procedure is developed. A practical example is presented to illustrate the strategic manipulation procedure. (C) 2020 Elsevier Inc. All rights reserved.

关键词： Multi-attribute decision making TOPSIS method Genetic optimization non-linear programming

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