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An optimisation model for the design of global multi-echelon supply chains under lead time constraints

INTERNATIONAL JOURNAL OF PRODUCTION RESEARCH 2013年第9期51卷 2760-2775页

作者： Hammami, Ramzi Frein, Yannick ESC Rennes Sch Business Dept Finance & Operat Rennes France UJF CNRS Grenoble INP G SCOP Grenoble France

This article presents a mixed integer programming model for the design of global multi-echelon supply chains while considering lead time constraints. Indeed, we impose that the delivery lead time that can be promised by the company must be smaller than the lead time required by the customer. The delivery lead time is calculated based on the lead times of purchasing, manufacturing and transportation that are triggered by the customer order while considering the stock levels of purchased, intermediate and final products that must be kept at the different facilities. Computational studies are conducted in order to analyse the impacts of including lead times on the supply chain design decisions and to prove the solvability of the model.

关键词： supply chain design lead times global logistics networks mixed integer programming

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Hybridization of Bound-and-Decompose and mixed integer Feasibility Checking to Measure Redundancy in Structured Linear Systems

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IEEE TRANSACTIONS ON AUTOMATION SCIENCE AND ENGINEERING 2013年第4期10卷 1151-1157页

作者： Bansal, Manish Kianfar, Kiavash Ding, Yu Moreno-Centeno, Erick Texas A&M Univ Dept Ind & Syst Engn College Stn TX 77843 USA

Computing the degree of redundancy for structured linear systems is proven to be NP-hard. A linear system whose model matrix is of size n x p is considered structured if some p row vectors in the model matrix are linearly dependent. Bound-and-decompose and 0-1 mixed integer programming (MIP) are two approaches to compute the degree of redundancy, which were previously proposed and compared in the literature. In this paper, first we present an enhanced version of the bound-and-decompose algorithm, which is substantially (up to 30 times) faster than the original version. We then present a novel hybrid algorithm to measure redundancy in structured linear systems. This algorithm uses a 0-1 mixed integer feasibility checking algorithm embedded within a bound-and-decompose framework. Our computational study indicates that this new hybrid approach significantly outperforms the existing algorithms as well as our enhanced version of bound-and-decompose in several instances. We also perform a computational study that shows matrix density has a significant effect on the runtime of the algorithms. Note to Practitioners-People have long realized the importance of having sensor or measurement redundancy in a system as this redundancy safeguards the system against sensor failures or measurement anomalies, so much so that the degree of redundancy is a reflection of the system's reliability or fault-tolerance capability. Because of dependence relationship among the system's components or subsystems, computing the degree of redundancy is not a straightforward matter for practical systems which embed certain structure. Our paper presents an enhanced version of an existing method as well as a novel hybrid algorithm to calculate degree of redundancy, which are significantly faster than the existing methods in many cases. These algorithms are a step forward in addressing this challenging problem.

关键词： Degree of redundancy mixed integer programming bound-and-decompose NP-hard structured linear model

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An MILP Based Formulation for Short-Term Hydro Generation Scheduling With Analysis of the Linearization Effects on Solution Feasibility

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IEEE TRANSACTIONS ON POWER SYSTEMS 2013年第4期28卷 3588-3599页

作者： Tong, Bo Zhai, Qiaozhu Guan, Xiaohong Xi An Jiao Tong Univ Syst Engn Inst Xian 710049 Peoples R China Xi An Jiao Tong Univ MOE KLINNS Lab Xian 710049 Peoples R China Tsinghua Univ Ctr Intelligent & Networked Syst Beijing 100084 Peoples R China

mixed integer linear programming (MILP) based formulations and solution methods for short-term hydro generation scheduling (HGS) have been widely adopted by researchers, hydropower producers, and system operators in recent years. This approach calls for the nonlinear forebay level, tailrace level, penstock loss, and hydropower production functions to be replaced with their piecewise linear approximations. However, the effects of the linearization of the nonlinear functions and related constraints on solution feasibility have not been fully discussed in the literature. In this paper, the issues concerning solution feasibility are discussed in detail and a method is presented to ensure that the solution obtained based on the approximated MILP formulation remains feasible for the original nonlinear formulation. Furthermore, it is found that the real number water delay can be handled in the formulation without destroying the linear structure of the water balance constraints. Numerical testing results show that the method presented in this paper is effective.

关键词： Cascaded reservoirs error analysis head-dependent hydro generation mixed integer programming short-term hydro generation scheduling

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Process design and supply chain optimization of supercritical biodiesel synthesis from waste cooking oils

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CHEMICAL ENGINEERING RESEARCH & DESIGN 2013年第8期91卷 1456-1466页

作者： Kelloway, Adam Marvin, W. Alex Schmidt, Lanny D. Daoutidis, Prodromos Univ Minnesota Dept Chem Engn & Mat Sci Minneapolis MN 55455 USA

A small scale biodiesel production facility based on the Mcgyan process is simulated in HYSYS and a follow-up techno-economic analysis is performed. Two feedstocks are analyzed: a soybean oil and waste cooking oil analogs. It is found that the soybean oil based process is not economical at such small scales, whereas the waste oil case has an NPV of $618K with an internal rate of return of 80%. The economic feasibility of a distributed system of small scale biodiesel production facilities in Greater London using waste vegetable cooking feedstock is also investigated. It is found that this system is feasible with a total of 20 installed facilities and an NPV of $1.1MM. A scheme is then implemented which reduces the total capital expenditure per facility based on the mass production of similar facilities. As expected, this scheme reduces the total capital cost of the system. Finally, a Monte Carlo scheme is implemented to study how the variability in economic parameters affects the system. It is found that the system is most sensitive to the sale price of biodiesel but that in all cases a positive NPV is returned. These analyses support the feasibility of small scale locally based biofuel production from locally sourced feestocks. (C) 2013 The Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.

关键词： Biodiesel Facility location mixed integer programming

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Power optimization in ad hoc wireless network topology control with biconnectivity requirements

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COMPUTERS & OPERATIONS RESEARCH 2013年第12期40卷 3188-3196页

作者： Moraes, Renato E. N. Ribeiro, Celso C. Univ Fed Fluminense Dept Comp Sci BR-24210240 Niteroi RJ Brazil

We consider the problem of assigning transmission powers to the nodes of an ad hoc wireless network, so that the total power consumed is minimized and the resulting network is biconnected, i.e., there are at least two node-disjoint paths between any pair of nodes. Biconnected communication graphs are important to ensure fault tolerance, since ad hoc networks are used in critical application domains where failures are likely to occur. A mixed integer programming formulation of the problem can be exactly solved to optimality by a commercial solver only for moderately sized problems. We recall a mixed integer programming formulation that can be exactly solved to optimality by a commercial solver only for very moderately sized problems. We propose a quick greedy algorithm and a GRASP with path-relinking heuristic for solving real-life sized problems. Computational experiments involving practical issues such as energy consumption and interference have been performed and reported for problems with up to 800 nodes, illustrating the effectiveness and the efficiency of the new algorithms. Both the greedy algorithm and the GRASP heuristic outperformed the best heuristic in the literature for very large problem sizes. (C) 2012 Elsevier Ltd. All rights reserved.

关键词： Wireless networks Ad hoc networks Topology control Biconnectivity Fault tolerance Energy consumption optimization GRASP Path-relinking mixed integer programming

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Coordinated decisions for transmission and generation expansion planning in electricity markets

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INTERNATIONAL TRANSACTIONS ON ELECTRICAL ENERGY SYSTEMS 2013年第8期23卷 1452-1467页

作者： Moghaddam, Maziar Mirhosseini Javidi, Mohammad Hossein Moghaddam, Mohsen Parsa Buygi, Majid Oloomi Islamic Azad Univ Sci & Res Branch Dept Elect Engn Tehran Iran Ferdowsi Univ Mashhad Dept Elect Engn Mashhad Iran Tarbiat Modares Univ Dept Elect Engn Tehran Iran

This paper presents a new approach to coordinate the decisions of transmission and generation capacity expansion planning for a competitive electricity market in which only the generation sector is deregulated. The independent system operator (ISO) as transmission planner has a regulatory role in the strategic behavior of generation companies. To reach coordinated decisions, the model relies on an interactive and iterative process between generation expansion planning and transmission expansion planning. This repetitive process continues until reaching a converging point or fulfilling the stopping criterion assigned by the ISO. In order to consider random outages of network components as well as uncertainty of load and bid prices of generating units, the Monte Carlo simulation method is applied. The simulation results confirm the efficacy of the proposed model in the coordinated generation and transmission planning problem considering the uncertainties. Copyright (c) 2012 John Wiley & Sons, Ltd.

关键词： competitive electricity market coordinated decisions between generation and transmission planning mixed integer programming Monte Carlo simulation random outages and uncertainty system reliability

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Optimization-based decision support for scenario analysis in electronic sourcing markets with volume discounts

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ELECTRONIC COMMERCE RESEARCH AND APPLICATIONS 2013年第3期12卷 152-165页

作者： Hass, Christian Bichler, Martin Guler, Kemal Tech Univ Munich Dept Informat Munich Germany Hewlett Packard Labs Palo Alto CA USA

E-Sourcing software has become an integral part of electronic commerce. Beyond the use of single-lot auction formats, there has been an emerging interest in using e-sourcing software for complex negotiations. Procurement markets typically exhibit scale economies leading to various types of volume discounts which are in wide-spread use in practice. The analysis of bids in such negotiations typically leads to computationally hard optimization problems. Scenario analysis describes a process, in which procurement managers compute different award allocations as a result of different allocation constraints and parameters that they put in place. This paper discusses an optimization model and computational methods which allow for effective scenario analysis with allocation problems in the presence of different types of discount policies and allocation constraints. The model reduces the number of parameter settings to explore considerably. The models are such that they can often not be solved exactly for realistic problem sizes in practically acceptable time frames. Therefore, we provide results of numerical experiments using exact algorithms and heuristics to solve the problem. We find that RINS and Variable Neighborhood Search can be effectively used in traditional branch-and-cut algorithms for this problem. Overall, new computational approaches allow procurement managers to evaluate offers even in markets with a complex set of volume discounts and multiple allocation constraints. (C) 2013 Elsevier B.V. All rights reserved.

关键词： Electronic market Volume discount mixed integer programming

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Lower and upper bounds for location-arc routing problems with vehicle capacity constraints

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EUROPEAN JOURNAL OF OPERATIONAL RESEARCH 2013年第1期224卷 189-208页

作者： Doulabi, Seyed Hossein Hashemi Seifi, Abbas Amirkabir Univ Technol Dept Ind Engn Tehran Iran Amirkabir Univ Technol Ind Engn & Prod Res Ctr Tehran Iran

This paper addresses multi-depot location arc routing problems with vehicle capacity constraints. Two mixed integer programming models are presented for single and multi-depot problems. Relaxing these formulations leads to other integer programming models whose solutions provide good lower bounds for the total cost. A powerful insertion heuristic has been developed for solving the underlying capacitated arc routing problem. This heuristic is used together with a novel location-allocation heuristic to solve the problem within a simulated annealing framework. Extensive computational results demonstrate that the proposed algorithm can find high quality solutions. We also show that the potential cost saving resulting from adding location decisions to the capacitated arc routing problem is significant. (C) 2012 Elsevier B.V. All rights reserved.

关键词： Location-arc routing Arc routing Integrated logistics mixed integer programming Heuristics

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Scheduling of Intelligent and Autonomous Vehicles under pairing/unpairing collaboration strategy in container terminals

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TRANSPORTATION RESEARCH PART C-EMERGING TECHNOLOGIES 2013年 33卷 1-21页

作者： Gelareh, Shahin Merzouki, Rochdi McGinley, Kay Murray, Roisin UArtois LGI2A F-62400 Bethune France Ecole Polytech Lille CNRS LAGIS UMR 8219 F-59655 Villeneuve Dascq France Univ Lille Nord France F-59000 Lille France Ecole Polytech Lille F-59655 Villeneuve Dascq France Dublin Inst Technol Dept Transport Engn Dublin 1 Ireland

A new class of Intelligent and Autonomous Vehicles (IAVs) has been designed in the framework of Intelligent Transportation for Dynamic Environment (InTraDE) project funded by European Union. This type of vehicles is technologically superior to the existing Automated Guided Vehicles (AGVs), in many respects. They offer more flexibility and intelligence in maneuvering within confined spaces where the logistic operations take place. This includes the ability of pairing/unpairing enabling a pair of 1-TEU (20-foot Equivalent Unit) lAVs dynamically to join, transport containers of any size between 1-TEU and 1-FFE (40-foot Equivalent) and disjoin again. Deploying IAVs helps port operators to remain efficient in coping with the ever increasing volume of container traffic at ports and eliminate the need for deploying more 40-ft transporters in the very confined area of ports. In order to accommodate this new feature of IAVs, we review and extend one of the existing mixed integer programming models of AGV scheduling in order to minimize the makespan of operations for transporting a set of containers of different sizes between quay cranes and yard cranes. In particular, we study the case of Dublin Ferryport Terminal. In order to deal with the complexity of the scheduling model, we develop a Lagrangian relaxation-based decomposition approach equipped with a variable fixing procedure and a primal heuristics to obtain high-quality solution of instances of the problem. (C) 2013 Elsevier Ltd. All rights reserved.

关键词： Intelligent Autonomous Vehicle Automated guided vehicle mixed integer programming Scheduling Lagrangian relaxation Discrete-event simulation

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A combined optimization-simulation approach to the master surgical scheduling problem

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IMA JOURNAL OF MANAGEMENT MATHEMATICS 2013年第2期24卷 155-187页

作者： Banditori, Carlo Cappanera, Paola Visintin, Filippo Univ Florence Informat Based Ind Serv Lab Dept Ind Engn Florence Italy Univ Florence Informat Based Ind Serv Lab Dipartimento Sistemi & Informat Florence Italy

This paper addresses the master surgical scheduling problem. First, we present a mixed integer programming model. The model assumes that the cases in a hospital's waiting list can be classified into homogeneous surgery groups based on the resources (e.g. operating room, post-surgical beds) that they are expected to require. Hence, it produces a solution that indicates, for each day of the month and for each time slot of the day, the number of cases to treat and the surgery group these cases must belong to. The model maximizes the patient throughput, takes into account the cases' due dates and allows for control of the waiting list. Secondly, we illustrate the results of a simulation study through which we test the model solution's robustness against the randomness of surgery duration and the length of stay. Finally, we present a combined optimization simulation approach that allows us to fine tune the optimization model to trade-off robustness and efficiency. Our study shows that, by planning surgery groups instead of individual cases and by combining optimization and simulation, it is possible to obtain schedules that are both robust and easy to implement. In addition, it shows that such a combined approach allows for the performance of more accurate scenario analyses. The results presented in this paper are based on real data from the Meyer University Children's Hospital in Florence, which is one of the most renowned children's hospitals in Italy.

关键词： master surgical schedule mixed integer programming simulation children's hospital health care

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