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A new model for open-pit production and waste-dump scheduling

ENGINEERING OPTIMIZATION 2019年第4期51卷 718-732页

作者： Fu, Zhao Asad, Mohammad Waqar Ali Topal, Erkan Curtin Univ Western Australian Sch Mines Dept Min Engn & Met Engn Kalgoorlie Australia

An open-pit mine schedule defines the optimal sequence of mining valuable (ore) and waste material with the objective of maximizing the value of the project. Given this production schedule, a waste-dump schedule is then developed to determine the optimal waste-rock allocation in waste dumps. Thus, production and waste-dump schedules are managed separately, which leads to an inappropriate consideration of the material haulage cost, suboptimal schedules generating less value, and the incorrect classification of ore and waste. This article proposes a mixed-integer programming-based model that determines the optimal production and waste-rock dumping schedule concurrently with the objective of maximizing the discounted cash flow [net present value (NPV)] of the project. An implementation of the proposed model on a gold-mining operation outperforms the two existing methods [traditional and two-step mixed-integer programming (TSMIP) model] in the context of project NPV as well as its practicality.

关键词： Operations Research in natural resources open-pit mining mixed-integer programming production scheduling mine waste management

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Traffic Signal Optimization: Combining Static and Dynamic Models

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TRANSPORTATION SCIENCE 2019年第1期53卷 21-41页

作者： Koehler, Ekkehard Strehler, Martin Brandenburg Tech Univ Cottbus D-03046 Cottbus Germany

In this paper, we present a cyclically time-expanded network model for simultaneous optimization of traffic assignment and traffic signal parameters, in particular, offsets, split times, and phase orders. Since travel times are of great importance for developing realistic solutions for traffic assignment and traffic signal coordination in urban road networks, we perform an extensive analysis of the model. We give an example showing that a linear time-expanded model can reproduce realistic nonconvex travel times especially for use with traffic signals and we verify this by simulation. Furthermore, we show how exact mathematical programming techniques-namely, mixed-integer linear programming-can be used for optimizing the control of traffic signals. We provide computational results for real-world instances and demonstrate the capabilities of the cyclically time-expanded model by simulation results obtained with state-of-the-art traffic simulation tools.

关键词： traffic signal optimization traffic assignment cyclically time-expanded network flow over time link performance mixed-integer programming

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Exact methods for order acceptance and scheduling on unrelated parallel machines

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COMPUTERS & OPERATIONS RESEARCH 2019年 104卷 159-173页

作者： Wang, Shijin Ye, Benyan Tongji Univ Sch Econ & Management Shanghai 200092 Peoples R China

This paper studies an order acceptance and scheduling (OAS) problem on unrelated parallel machines to maximize the total net revenue of accepted orders, which is the difference between sum of revenues and total weighted tardiness. Two mixed-integer programming (MIP) models are formulated, which are further improved with various enhancement techniques. A formulation-based branch-and-bound algorithm is developed in an attempt to handle complicated instances following the principle of "divide and conquer". Extensive computational experiments on various instances are conducted, and the results demonstrate the efficiency of the enhancement techniques for the formulations, as well as the effectiveness and efficiency of the formulation-based branch-and-bound algorithm. The proposed branch-and-bound algorithm can optimally solve instances with up to 50 jobs and different number of machines within the time limit of half an hour. (C) 2018 Elsevier Ltd. All rights reserved.

关键词： Order acceptance and scheduling Unrelated parallel machines mixed-integer programming Branch-and-bound

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Models and a solution algorithm for planning transfer synchronization of bus timetables

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TRANSPORTATION RESEARCH PART E-LOGISTICS AND TRANSPORTATION REVIEW 2019年 131卷 247-266页

作者： Chu, James C. Korsesthakarn, Kanticha Hsu, Yu-Ting Wu, Hua-Yen Natl Taiwan Univ Dept Civil Engn Taipei Taiwan

mixed-integer linear programming models and a heuristic algorithm are proposed for the transfer synchronization planning of bus timetables. The most important novelty of the proposed methodology is that the bus timetables and passenger choices of travel paths are simultaneously optimized in the model. The possibilities of transfer synchronization are fully explored in the timetable optimization because passengers select their paths to the destination in response to the timetables. Hence, bus timetables can be planned with high precision, and bus timetabling can be improved.

关键词： Bus timetabling Passenger transfer Transfer synchronization mixed-integer programming Heuristic algorithm

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Simultaneous lotsizing and scheduling considering secondary resources: a general model, literature review and classification

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OR SPECTRUM 2019年第1期41卷 1-43页

作者： Woerbelauer, Martin Meyr, Herbert Almada-Lobo, Bernardo Univ Hohenheim Dept Supply Chain Management Stuttgart Germany Univ Porto INESC TEC Fac Engn Porto Portugal

Typical simultaneous lotsizing and scheduling models consider the limited capacity of the production system by respecting a maximum time the respective machines or production lines can be available. Further limitations of the production quantities can arise by the scarce availability of, e.g., setup tools, setup operators or raw materials which thus cannot be neglected in optimization models. In the literature on simultaneous lotsizing and scheduling, these production factors are called secondary resources. This paper provides a structured overview of the literature on simultaneous lotsizing and scheduling involving secondary resources. The proposed classification yields for the first time a unified view of scarce production factors. The insights about different types of secondary resources help to develop a new model formulation generalizing and extending the currently used approaches that are specific for some settings. Some illustrative examples demonstrate the functional principle and flexibility of this new formulation which can thus be used for a wide range of applications.

关键词： Scheduling Dynamic lotsizing Secondary resources mixed-integer programming

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Scheduling elective patients based on sequence-dependent setup times in an open-heart surgical department using an optimization and simulation approach

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SIMULATION-TRANSACTIONS OF THE SOCIETY FOR MODELING AND SIMULATION INTERNATIONAL 2019年第12期95卷 1141-1164页

作者： Hamid, Mahdi Hamid, Mojtaba Musavi, MirMohammad Azadeh, Ali Univ Tehran Coll Engn Sch Ind Engn Field Ind Engn Tehran Iran Iran Univ Sci & Technol Dept Ind Engn Tehran Iran Univ Tehran Coll Engn Sch Ind Engn POB 515-14395 Tehran Iran

The surgery ward is the most expensive and profitable section of a hospital. The decisions made in this section therefore produce significant effects on the overall performance of the hospital. Planning and scheduling of the surgeries in the operating rooms would obviously lead to the enhancement of the performance of the operating rooms. The setup time of the operating rooms is a very important factor in initiating next surgeries and consequently in the scheduling of elective patients. The preparation time is usually affected by the sequence of the surgeries, especially in critical and longer surgeries, such as open-heart surgeries. In this study, a two-stage procedure is applied to improve the performance of the open-heart surgical department. In the first stage, a mathematical model is proposed for planning and scheduling of the surgeries in the open-heart surgery ward, considering the sequence-dependent setup times. In the next stage, an estimation of the optimum number of intensive care unit beds is provided using the discrete event simulation method. Finally, using a real-life example, the applicability of the proposed model is demonstrated and an analysis of the effect of the recommended number of intensive care unit beds-extracted from the simulation model-on the performance of the surgical theater is performed.

关键词： Operating room scheduling sequence-dependent setup time mixed-integer programming intensive care unit discrete event simulation

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Learning in Combinatorial Optimization: What and How to Explore

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OPERATIONS RESEARCH 2020年第5期68卷 1585-1604页

作者： Modaresi, Sajad Saure, Denis Vielma, Juan Pablo Univ N Carolina Kenan Flagler Business Sch Chapel Hill NC 27599 USA Univ Chile Ind Engn Dept Beauchef 851 Santiago 8370456 Chile MIT Sloan Sch Management Cambridge MA 02142 USA

We study dynamic decision making under uncertainty when, at each period, a decision maker implements a solution to a combinatorial optimization problem. The objective coefficient vectors of said problem, which are unobserved before implementation, vary from period to period. These vectors, however, are known to be random draws from an initially unknown distribution with known range. By implementing different solutions, the decision maker extracts information about the underlying distribution but at the same time experiences the cost associated with said solutions. We show that resolving the implied exploration versus exploitation tradeoff efficiently is related to solving a lower-bound problem (LBP), which simultaneously answers the questions of what to explore and how to do so. We establish a fundamental limit on the asymptotic performance of any admissible policy that is proportional to the optimal objective value of the LBP problem. We show that such a lower bound might be asymptotically attained by policies that adaptively reconstruct and solve the LBP at an exponentially decreasing frequency. Because the LBP is likely intractable in practice, we propose policies that instead reconstruct and solve a proxy for the LBP, which we call the optimality cover problem (OCP). We provide strong evidence of the practical tractability of the OCP, which implies that the proposed policies can be implemented in real time. We test the performance of the proposed policies through extensive numerical experiments, and we show that they significantly outperform relevant benchmarks in the long-term and are competitive in the short-term.

关键词： combinatorial optimization multiarmed bandit mixed-integer programming

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Ten years of feasibility pump, and counting

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EURO JOURNAL ON COMPUTATIONAL OPTIMIZATION 2019年第1期7卷 1-14页

作者： Berthold, Timo Lodi, Andrea Salvagnin, Domenico Fair Isaac Berlin Germany CERC Montreal PQ Canada Ecole Polytech Montreal Montreal PQ Canada Univ Padua DEI Padua Italy

The Feasibility Pump (fp) is probably the best-known primal heuristic for mixed-integer programming. The original work by Fischetti et al. (Math Program 104(1):91-104, 2005), which introduced the heuristic for 0-1 mixed-integer linear programs, has been succeeded by more than twenty follow-up publications which improve the performance of the fp and extend it to other problem classes. Year 2015 was the tenth anniversary of the first fp publication. The present paper provides an overview of the diverse Feasibility Pump literature that has been presented over the last decade.

关键词： mixed-integer programming Primal heuristics mixed-integer programming solvers

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A Mechanism for Pricing and Allocation of Mobility Permits on Single-Bottleneck Roadways 5

A Mechanism for Pricing and Allocation of Mobility Permits o...

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5th International Conference on Transportation Information and Safety (ICTIS)

作者： Lessan, Javad Fu, Liping Bachmann, Chris Univ Waterloo Dept Civil & Environm Engn Waterloo ON N2L 3G1 Canada Southwest Jiaotong Univ Sch Transportat & Logist Chengdu 610031 Peoples R China

ISBN: (纸本)9781728104898

This paper deals with the pricing and allocation problems that arise in a mobility permit (MP)-based traffic management system on single bottleneck roadways. We present a permit endowment (pricing and allocation) mechanism and address the efficiency of such a system in mitigating the congestion at bottlenecks under users' preferences and incomplete information setting. To perform an efficient permit allocation, we develop a mixed-integer programming (MIP) optimization model restrained by user priority and MP availability constraints. For the pricing problem, we present an iterative auction mechanism on top of the MIP-based permit allocation module. We present a performance comparison of the presented mechanism against hypothetical coordinated and centralized efficiency-oriented and equity-oriented systems. Computational results show the potential of the proposed pricing and allocation mechanism for managing MPs in a network with a single-bottleneck roadway where the mobility users, mobility service provider, and system regulator's concerns must be integrated into a MP-based traffic congestion management solution.

关键词： Traffic congestion Single-bottleneck Roadways Mobility Permits Pricing and Allocation Efficiency mixed-integer programming

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A variable MIP neighborhood descent for the multi-attribute inventory routing problem

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TRANSPORTATION RESEARCH PART E-LOGISTICS AND TRANSPORTATION REVIEW 2020年 144卷

作者： Coelho, Leandro Callegari De Maio, Annarita Lagana, Demetrio Univ Laval CIRRELT Quebec City PQ Canada Univ Laval Canada Res Chair Integrated Logist Quebec City PQ Canada Univ Calabria Dept Mech Energy & Management Engn DIMEG Via P BucciCubo 41C I-87036 Arcavacata Di Rende CS Italy

In this paper we study a Multi-Attribute Inventory Routing Problem (MAIRP). A mathematical formulation and exact solution algorithms are introduced for this problem. More precisely, we extend the Multi-Depot Inventory Routing Problem (MDIRP) in order to consider the multiproduct case with a heterogeneous fleet of vehicles and explicit constraints for the route duration. The MAIRP is an NP-hard problem more complex than the classical Inventory Routing Problem. Moreover, it captures many features that can be found in real applications of a vendor managed inventory strategy. We introduce a hybrid exact algorithm to solve it, in which several mixed integer programming (MIP) models are solved to explore the neighborhoods of a Variable Neighborhood Search (VNS) scheme applied to the MAIRP. We design several neighborhoods that are based on the features of the problem. The impact of this hybridization is a faster convergence of the model and an accelerated resolution process with respect to a branch-and-cut algorithm applied to the regular MIP formulation. Extensive computational results on new and existing instances from the literature on two benchmark problems and a real data set confirm the high efficiency of our algorithm.

关键词： Variable neighborhood search mixed-integer programming Inventory routing problem Exact algorithm

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