检索结果-内蒙古大学图书馆

Robotic mobile fulfillment systems: a mathematical modelling framework for e-commerce applications

INTERNATIONAL JOURNAL OF PRODUCTION RESEARCH 2022年第11期60卷 3589-3605页

作者： Rimele, Adrien Gamache, Michel Gendreau, Michel Grangier, Philippe Rousseau, Louis-Martin Polytech Montreal Dept Math & Ind Engn Montreal PQ Canada CIRRELT Interuniv Res Ctr Enterprise Networks Logist & Tr Montreal PQ Canada GERAD Grp Res Decis Anal Montreal PQ Canada IVADO Labs Montreal PQ Canada

Robotic Mobile Fulfillment Systems (RMFSs) are a recent type of automated warehouse deployed in e-commerce. In this parts-to-picker system, a fleet of small robots is tasked with retrieving and storing shelves of items in the warehouse. Due to the nature of the e-commerce market, and the high flexibility of RMFSs, there are many opportunities to improve the productivity of the warehouse by optimising operational decisions. Online retailers promise extremely fast deliveries, which requires that new orders be included in the set of requests to fulfil as soon as they are revealed. For this reason, and because of the very dynamic nature of the robots' cycles, decision-making needs to be done in real time, in an uncertain environment. Because such a problem often lacks a formal description, we propose a mathematical framework that models the operational decisions taking place in an RMFS as a stochastic dynamic program. Our objective is to formalise optimisation opportunities, to allow researchers to develop more advanced methods in a well-defined environment. Embedded in a discrete event simulator, this model is illustrated by simulations to compare against standard storage decision rules.

关键词： warehouse e-commerce robotic mobile fulfillment system stochastic dynamic programming mathematical modelling simulations

来源：评论

学校读者我要写书评

暂无评论

The economic value of coordination in large-scale multireservoir systems: The Parana River case

引用

WATER RESOURCES RESEARCH 2013年第11期49卷 7546-7557页

作者： Marques, Guilherme Fernandes Tilmant, A. Ctr Fed Educ Tecnol Minas Gerais Dept Civil Engn BR-30510000 Belo Horizonte MG Brazil Univ Laval Dept Civil & Water Engn Quebec City PQ Canada

The coordination of reservoir operation is critical for water systems' efficiency. Improved coordination requires sharing information, demanding a clear understanding of the potential gains and its distribution among the users to motivate engagement in coordinated operations and bearing of transaction costs. In a multiuser, multireservoir system, the evaluation of the potential coordination gains is not trivial because it requires the simultaneous evaluation of numerous trade offs. This paper presents a methodology to identify the likely upper and lower bounds in multireservoir system benefits, providing a reference framework for analyzing the economic value of coordination. The methodology is applied to a large-scale multireservoir system in Brazil. The methods rely on the comparison between two management scenarios. The first one mimics typical system operation based on individually designed rule curves, which are likely to perform on the lower bound. This is compared with fullscale system-wide optimization through an stochastic Dual dynamic programming algorithm to represent fully coordinated reservoir operation (upper bound). For our case study, results indicate that better coordination reduced spills and improved releases timing according to reservoirs characteristics and location, allowing overall gains between 3% and 8% in energy and 7.9% in revenues, with revenues mostly improved by coordination in dry years. Larger reservoirs presented the highest gains in absolute terms, while the smaller ones presented the highest relative increases. By indicating individual gains at each reservoir, valuable information is produced to support future negotiations and benefit sharing among different agents, being water agencies or power companies.

关键词： reservoir operation hydropower optimization stochastic dynamic programming water systems coordination stochastic dual dynamic programming

来源：评论

学校读者我要写书评

暂无评论

Invasive species control in a one-dimensional metapopulation network

引用

ECOLOGICAL MODELLING 2015年 316卷 176-184页

作者： Walker, Adam N. Poos, Jan-Jaap Groeneveld, Rolf A. Wageningen UR Social Sci Grp NL-6706 KN Wageningen Netherlands Wageningen IMARES Inst Marine Resources & Ecosyst Studies NL-1970 AB Ijmuiden Netherlands

The growth and spread of established Invasive Alien Species (IAS) cause significant ecological and economic damages. Minimising the costs of controlling, and the damages from, IAS depends on the spatial dynamics and uncertainty regarding IAS spread. This study expands on existing modelling approaches by allowing for varying stock sizes within patches and stochastic spread between patches. The objective of this study is to demonstrate the added value from this more detailed modelling approach. This is achieved in the context of coastal and riparian systems, which can be accurately modelled one-dimensional landscape, i.e., a series of patches connected in a line. The model allows for two types of intervention, namely (1) partial or complete removal of the population in within any patch;and (2) containment to reduce spread between patches. We analyse the general properties of the model using a two-patch setup to determine how the optimal policy depends on both the location and size of the invasion in patches. We find that allowing for varying stock sizes within patches facilitates optimal timing of the application of containment. We also identify two novel optimal policies: the combination of containment and removal to stop spread between patches and the application of up to four distinct policies for a single patch depending on the size of the invasion in that patch. (C) 2015 Elsevier B.V. All rights reserved.

关键词： Spatial modelling stochastic dynamic programming Invasive alien species

来源：评论

学校读者我要写书评

暂无评论

Optimal production control policy in unreliable batch processing manufacturing systems with transportation delay

引用

INTERNATIONAL JOURNAL OF PRODUCTION RESEARCH 2013年第1期51卷 264-280页

作者： Bouslah, B. Gharbi, A. Pellerin, R. Hajji, A. Univ Quebec Ecole Technol Super Automated Prod Engn Dept Quebec City PQ Canada Ecole Polytech Dept Math & Ind Engn Montreal PQ H3C 3A7 Canada Univ Laval Dept Operat & Decis Syst Quebec City PQ Canada

This paper considers the problem of production planning of unreliable batch processing manufacturing systems. The finished goods are produced in lots, and are then transported to a storage area in order to continuously meet a constant demand rate. The main objective of this work is to jointly determine the optimal lot sizing and optimal production control policy that minimise the total expected cost of inventory/backlog and transportation, over an infinite time horizon. The decision variables are the lot sizing and the production rate. The problem is formulated with a stochastic dynamic programming model and the impulse control theory is applied to establish the Hamilton-Jacobi-Bellman (HJB) equations. Based on a numerical resolution of the HJB equations, it is shown that the optimal control policy is governed by a base stock policy for production rate control and economic lot size for batch processing. A thorough analysis and practical issues are addressed with a simulation-based approach. Thus, a combined discrete-continuous simulation model is developed to determine the optimal parameters of the proposed policy when the failure and repair times follow general distributions. The results are illustrated with numerical examples and confirmed through sensitivity analysis.

关键词： unreliable manufacturing systems economic production quantity feedback production planning stochastic dynamic programming simulation

来源：评论

学校读者我要写书评

暂无评论

AVERAGE COST OPTIMAL POLICIES FOR MARKOV CONTROL PROCESSES WITH BOREL STATE-SPACE AND UNBOUNDED COSTS

引用

SYSTEMS & CONTROL LETTERS 1990年第4期15卷 349-356页

作者： HERNANDEZLERMA, O LASSERRE, JB INST POLITECN NACL CINVESTAV DEPT MATEMAT MEXICO CITY 07000 DF MEXICO CNRS AUTOMAT & ANAL SYST F-31077 TOULOUSE FRANCE

We show the existence of average cost optimal stationary policies for Markov control processes with Borel state space and unbounded costs per stage, under a set of assumptions recently introduced by L.I. Sennott (1989... 详细信息

关键词： Controlled Markov chains (discrete-time Markov control processes) average cost stochastic dynamic programming optimal stationary policies

来源：评论

学校读者我要写书评

暂无评论

Optimal MAV operations in an uncertain environment

引用

INTERNATIONAL JOURNAL OF ROBUST AND NONLINEAR CONTROL 2008年第2期18卷 248-262页

作者： Pachter, Meir Chandler, Phillip R. Darbha, Swaroop AFRL VACA Wright Patterson AFB OH 45433 USA AFIT ENG Wright Patterson AFB OH 45433 USA Texas A&M Univ Dept Mech Engn College Stn TX 77843 USA

In this paper, we consider a problem of sequential resource allocation. Such a problem arises in a simplified intelligence, surveillance and reconnaissance scenario where a micro air vehicle (MAV) is tasked with classification in an environment with false, that is, clutter, targets. The MAV visits the objects of interest in a specified sequence. A human operator is tasked with aiding the MAV's automatic target recognition system with the classification of objects, based on the images sent to him from the MAVs. If the images do not resolve the ambiguity concerning the status of the object being classified, the operator may request that the object be revisited. In this paper, for the sake of exposition of the employed methods and clarity of presentation, we assume that every object may be revisited at most once. Each object can be revisited and re-examined in L >= I ways. There is an information gain whose value is given by the running reward. The information gain depends on the way an object is re-examined, and the feedback from the operator but it is the same for all the objects. There is a random operator delay in communicating his findings to the MAV and the probability density function of the delay is assumed known. The MAV has a limited fuel reserve and upon getting feedback from the operator (and hence, knowing the delay associated with the object of interest only and not with those that it must revisit in the future), it must decide whether to revisit the object and if so, which of the L ways is optimal so as to maximize the total expected reward. In every revisit, fuel is expended from the reserve and is proportional to twice the delay plus a fixed cost, which is dependent on the way in which the object is re-examined. We employ a stochastic dynamic programming approach to solve this problem. Specifically, for the case when L = 1, we show that there is an optimal threshold for each object and it is optimal to revisit the object if the delay is at most the thr

关键词： stochastic dynamic programming UAV MAV

来源：评论

学校读者我要写书评

暂无评论

Index heuristics for multiclass M/G/1 systems with nonpreemptive service and convex holding costs

引用

QUEUEING SYSTEMS 2003年第2期45卷 81-111页

作者： Glazebrook, KD Lumley, RR Ansell, PS Univ Edinburgh Sch Management Edinburgh EH8 9JY Midlothian Scotland Univ Newcastle Upon Tyne Dept Stat Newcastle Upon Tyne NE1 7RU Tyne & Wear England

We consider the optimal service control of a multiclass M/G/1 queueing system in which customers are served nonpreemptively and the system cost rate is additive across classes and increasing convex in the numbers present in each class. Following Whittle's approach to a class of restless bandit problems, we develop a Langrangian relaxation of the service control problem which serves to motivate the development of a class of index heuristics. The index for a particular customer class is characterised as a fair charge for service of that class. The paper develops these indices and reports an extensive numerical investigation which exhibits strong performance of the index heuristics for both discounted and average costs.

关键词： indexability index policy service control stochastic dynamic programming restless bandit

来源：评论

学校读者我要写书评

暂无评论

Coordinated quality control in a two-stage system

引用

IEEE TRANSACTIONS ON AUTOMATIC CONTROL 1999年第6期44卷 1166-1179页

作者： Yao, DD Zheng, SH Columbia Univ Dept Ind Engn & Operat Res New York NY 10027 USA Hong Kong Univ Sci & Technol Dept Informat & Syst Management Kowloon Peoples R China

The authors study a quality control problem in a two-stage system. They assume that at each stage units are processed in batches, and the rates are random variables with known distributions. Final products are supplied to customers under warranties or service contracts, with penalty costs associated with defective units. The focus is on coordinating the inspection procedures at the two stages. Using a stochastic dynamic programming approach, the authors show that the optimal policy at stage 1 is characterized by a sequence of thresholds, and at stage 2, by a priority structure, as well as a threshold structure. The key to optimality is a so-called K-submodularity property, which is a strengthening of the usual notion of submodularity.

关键词： quality control sequential threshold policy stochastic dynamic programming submodularity

来源：评论

学校读者我要写书评

暂无评论

ADAPT: A Price-Stabilizing Compliance Policy for Renewable Energy Certificates: The Case of SREC Markets

引用

OPERATIONS RESEARCH 2017年第6期65卷 1429-1445页

作者： Khazaei, Javad Coulon, Michael Powell, Warren B. Princeton Univ Dept Operat Res & Financial Engn Princeton NJ 08540 USA Univ Sussex Dept Business & Management Brighton BN1 9SL E Sussex England

Currently, most Renewable Energy Certificate (REC) markets are defined based on targets that create an artificial step demand function resembling a cliff. This target policy produces volatile prices that can make investing in renewables a risky proposition. In this paper, we propose an alternative policy called Adjustable dynamic Assignment of Penalties and Targets (ADAPT) that uses a sloped compliance penalty and a self-regulating requirement schedule, both designed to stabilize REC prices, helping to alleviate a common weakness of environmental markets. To capture market behavior, we model the market as a stochastic dynamic programming problem to understand how the market might balance the decision to use a REC now versus holding it for future periods (in the face of uncertain new supply). Then, we present and prove some of the properties of this market, and finally we show that this mechanism reduces the volatility of REC prices, which should stabilize the market and encourage long-term investment in renewables.

关键词： compliance policy renewable energy certificates stochastic dynamic programming price volatility mechanism design

来源：评论

学校读者我要写书评

暂无评论

Optimal stopping analysis of a radiation detection system to protect cities from a nuclear terrorist attack

引用

RISK ANALYSIS 2008年第2期28卷 353-371页

作者： Atkinson, Michael P. Cao, Zheng Wein, Lawrence M. Stanford Univ Grad Sch Business Stanford CA 94305 USA Inst Computat & Math Engn Stanford CA 94305 USA Stanford Univ Dept Phys Stanford CA 94305 USA

We formulate and analyze an optimal stopping problem concerning a terrorist who is attempting to drive a nuclear or radiological weapon toward a target in a city center. In our model, the terrorist needs to travel through a two-dimensional lattice containing imperfect radiation sensors at some of the nodes, and decides at each node whether to detonate the bomb or proceed. We consider five different scenarios containing various informational structures and two different sensor array topologies: the sensors are placed randomly or they form an outer wall around the periphery of the city. We find that sensors can act as a deterrent in some cases, and that the government prefers the outer wall topology unless the sensors have a very low detection probability and the budget is tight (so that they are sparsely deployed).

关键词： homeland security Stackelberg game stochastic dynamic programming

来源：评论

学校读者我要写书评

暂无评论

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案：

请选择收藏分类：

通借通还

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：