共查询到20条相似文献，搜索用时 15 毫秒
1.
Multiobjective multiproduct parcel distribution timetabling problem is concerned with generating effective timetables for parcel distribution companies that provide interdependent services (products) and have more than one objective. A parcel distribution timetabling problem is inherently multiobjective because of the multitude of criteria that can measure the performance of a timetable. This paper provides the mathematical formulation of the problem and applies the model to a real‐world case study. The application shows that without a common ground with the practitioners, it would be impossible to define the actual requirements and objectives of the company; problem definition is as important as model construction and solution method. 相似文献
2.
Ahmad Hemmati Lars Magnus Hvattum 《International Transactions in Operational Research》2017,24(5):929-942
Randomization is common in many implementations of metaheuristics, and is typically a main ingredient while considering adaptive large neighborhood search (ALNS). This paper considers a standard implementation of ALNS for maritime pickup and delivery problems, identifies seven randomized components in that implementation, and proposes and analyzes simple nonrandomized alternatives to those components. The results reveal that the randomized alternatives perform slightly better for one of seven components, the deterministic alternatives perform better for one component, while the randomized and deterministic alternatives have similar performance for the remaining five components. When analyzing runs with different initial solutions, there seems to be a larger variance in the results obtained with only randomized components, compared to the results with only deterministic components, even when the average results are similar. 相似文献
3.
This technical note concerns the predictive control of discrete‐time linear models subject to state, input and avoidance polyhedral constraints. Owing to the presence of avoidance constraints, the optimization associated with the predictive control law is non‐convex, even though the constraints themselves are convex. The inclusion of the avoidance constraints in the predictive control law is achieved by the use of a modified version of a mixed‐integer programming approach previously derived in the literature. The proposed modification consists of adding constraints to ensure that linear segments of the system trajectories between consecutive sampling times do not cross existing obstacles. This avoids the significant extra computation that would be incurred if the sampling time was reduced to prevent these crossings. Simulation results show that the inclusion of these additional constraints successfully prevents obstacle collisions that would otherwise occur. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
4.
Victor Cunha Iuri Santos Luciana Pessoa Silvio Hamacher 《International Transactions in Operational Research》2020,27(1):197-218
This paper addresses a real‐life rescheduling problem of a pipe‐laying support vessel (PLSV) fleet in charge of subsea oil well connections. The short‐term schedule of these vessels is subject to uncertainties inherent to its operations, resulting in ships idleness or delays in oil production. The objective of this study is to develop methods to support a Brazilian oil and gas company in overcoming impacts caused by operational disruptions, while reaching its planned production level. The PLSV rescheduling problem was treated as an identical parallel machine scheduling problem, where the machines represent the vessels and the jobs are the activities for the subsea well connections. We propose a mathematical programming model and a method based on the iterated local search (ILS) metaheuristic to solve the problem. This paper contributes to this by considering simultaneously setup times, machine eligibility, release dates, due dates, and machine availability. Both methods were applied on 10 instances based on real PLSV data. Taking into account an objective function that measures the operational impact on schedules, the ILS provided an average improvement above 91% in schedules when compared to the initial solution provided by the studied company. The ILS outperformed a mathematical programming model for the problem, in eight instances, within a 30‐minute execution time limit, fitting to the company process. 相似文献
5.
Martin Riedler Thomas Jatschka Johannes Maschler Günther R. Raidl 《International Transactions in Operational Research》2020,27(1):573-613
We consider a resource‐constrained project scheduling problem originating in particle therapy for cancer treatment, in which the scheduling has to be done in high resolution. Traditional mixed integer linear programming techniques such as time‐indexed formulations or discrete‐event formulations are known to have severe limitations in such cases, that is, growing too fast or having weak linear programming relaxations. We suggest a relaxation based on partitioning time into so‐called time‐buckets. This relaxation is iteratively solved and serves as basis for deriving feasible solutions using heuristics. Based on these primal and dual solutions and bounds, the time‐buckets are successively refined. Combining these parts, we obtain an algorithm that provides good approximate solutions soon and eventually converges to an optimal solution. Diverse strategies for performing the time‐bucket refinement are investigated. The approach shows excellent performance in comparison to the traditional formulations and a metaheuristic. 相似文献
6.
用于炼油厂原油库存调度的混合模拟退火算法 总被引：1，自引：0，他引：1
现有的数学规划法在解决原油库存调度优化问题时存在着组合爆炸的问题,是阻碍调度优化实用化的主要原因。由于实践中往往只要求快速地获得一个较好解,因此作为启发式算法之一的模拟退火法,在解决调度问题的实用化方面具有很大的优越性。但由于模拟退火法较适于处理无约束的整数规划问题,而在原油库存调度优化模型中却存在着大量的实数约束,所以在其中直接应用模拟退火法比较困难。该文将模拟退火法与线性规划法相结合,以前者调动后者,后者为前者提供可行解判据,构成了一种优化混合算法。在将混合算法应用于原油库存调度问题时,该文采用了特定的编码方式,使各控制变量在随机变化时尽量满足相关的约束条件,从而避免了许多无效解的产生。实例计算结果表明,同传统的混合整数线性规划方法相比,这种混合算法可以快速地给出优化解,其优化值与全局最优值差别不大,表明混合算法可以更好地解决实际原油调度问题。 相似文献
7.
Ana Anoki&#x; Zorica Stanimirovi&#x; Tatjana Davidovi&#x; &#x;or&#x;e Staki&#x; 《International Transactions in Operational Research》2020,27(1):26-56
A vehicle scheduling problem (VSP) that arises from sugar beet transportation within minimum working time under the set of constraints reflecting a real‐life situation is considered. A mixed integer quadratically constrained programming (MIQCP) model of the considered VSP and reformulation to a mixed integer linear program (MILP) are proposed and used within the framework of Lingo 17 solver, producing optimal solutions only for small‐sized problem instances. Two variants of the variable neighborhood search (VNS) metaheuristic—basic VNS (BVNS) and skewed VNS (SVNS) are designed to efficiently deal with large‐sized problem instances. The proposed VNS approaches are evaluated and compared against Lingo 17 and each other on the set of real‐life and generated problem instances. Computational results show that both BVNS and SVNS reach all known optimal solutions on small‐sized instances and are comparable on medium‐ and large‐sized instances. In general, SVNS significantly outperforms BVNS in terms of running times. 相似文献
8.
Claudia Archetti Nicola Bianchessi Stefan Irnich M. Grazia Speranza 《International Transactions in Operational Research》2014,21(3):353-374
In this paper, we present and compare formulations for the inventory routing problem (IRP) where the demand of customers has to be served, over a discrete time horizon, by capacitated vehicles starting and ending their routes at a depot. The objective of the IRP is the minimization of the sum of inventory and transportation costs. The formulations include known and new mathematical programming formulations. Valid inequalities are also presented. The formulations are tested on a large set of benchmark instances. One of the most significant conclusions is that the formulations that use vehicle‐indexed variables are superior to the more compact, aggregate formulations. 相似文献
9.
Sydney C.K. Chu 《International Transactions in Operational Research》1994,1(3):271-283
The background of this study is a rather classical but complex inventory control/production planning/line scheduling problem of a major soft-drink company in Hong Kong. The issue that stands out for this many-product high-sales manufacturer is the storage space of its central warehouse, which often finds itself in the state of overflow or near capacity with finished goods and work-in-process inventory. This phenomenon can create immediate interruptions of production, capital tie-ups and subsequent potential of lost sales. Another obviously important concern is the meeting of forecast demands. A mathematical modelling approach that entails techniques of multi-period aggregate optimization is proposed to tackle the overall problem. The dual objectives are to achieve better production planning and line scheduling in order to minimize inventory build-up and maximize demand satisfaction. Numerical results for a sample problem are reported as an illustration to this proposed two-phase approach. 相似文献
10.
Yuh-Chyun Luo Monique Guignard Chun-Hung Chen 《Journal of Intelligent Manufacturing》2001,12(5-6):509-519
Hybrid methods are promising tools in integer programming, as they combine the best features of different methods in a complementary fashion. This paper presents such a framework, integrating the notions of genetic algorithm, linear programming, and ordinal optimization in an effort to shorten computation times for large and/or difficult integer programming problems. Capitalizing on the central idea of ordinal optimization and on the learning capability of genetic algorithms to quickly generate good feasible solutions, and then using linear programming to solve the problem that results from fixing the integer part of the solution, one may be able to obtain solutions that are close to optimal. Indeed ordinal optimization guarantees the quality of the solutions found. Numerical testing on a real-life complex scheduling problem demonstrates the effectiveness and efficiency of this approach. 相似文献
11.
Sameh Al‐Shihabi Mohammad M. AlDurgam 《International Transactions in Operational Research》2020,27(6):2841-2877
Contractors in the construction sector face several trade‐offs between time and cost. The time–cost trade‐off (TCT) is one of these trade‐offs where contractors can reduce a project completion time by assigning more resources to activities, which means spending more money, to shorten the execution times of project activities. On the other hand, contractors who finance their projects through credit lines from banks such that if they reach their credit limits, then the start times of some project activities can be delayed until cash is available again, which might lead to an increase in the project execution time; thus, contractors need to consider the time–credit trade‐off. In this work, we simultaneously consider these two trade‐offs that affect the project completion time and use mixed integer linear programming (MILP) to model the contractor time–cost–credit trade‐off (TCCT) problem. The MILP model minimizes the project execution time given the contractor's budgetary and financial constraints. In addition to the MILP model, we also develop a heuristic solution algorithm to solve the problem. Through a set of benchmark instances, we study the effectiveness of the heuristic algorithm and the computation time of the exact model. It is found that a good upper bound for the MILP results in less computation time. We also study some practical aspects of the problem where we highlight the importance of expediting contractor payments in addition to selecting a financially stable contractor. Finally, we use our MILP model to help a contractor bid for a project. 相似文献
12.
Marcela Monroy‐Licht Ciro Alberto Amaya André Langevin Louis‐Martin Rousseau 《International Transactions in Operational Research》2017,24(6):1325-1346
In this paper, the rescheduling arc routing problem is introduced. This is a dynamic routing and scheduling problem that considers adjustments to an initial routing itinerary when one or more vehicle failures occur during the execution stage and the original plan must be modified. We minimize the operational and schedule disruption costs. Formulations based on mixed‐integer programming are presented to compare different policies in the rerouting phase. A solution strategy is developed when both costs are evaluated and it is necessary to find a solution quickly. Computational tests on a large set of instances compare the different decision‐maker policies. 相似文献
13.
Mateus Martin Ernesto G. Birgin Rafael D. Lobato Reinaldo Morabito Pedro Munari 《International Transactions in Operational Research》2020,27(2):767-793
In this paper, we address the constrained two‐dimensional rectangular guillotine single large placement problem (2D_R_CG_SLOPP). This problem involves cutting a rectangular object to produce smaller rectangular items from orthogonal guillotine cuts. In addition, there is an upper limit on the number of copies that can be produced of each item type. To model this problem, we propose a new pseudopolynomial integer nonlinear programming (INLP) formulation and obtain an equivalent integer linear programming (ILP) formulation from it. Additionally, we developed a procedure to reduce the numbers of variables and constraints of the integer linear programming (ILP) formulation, without loss of optimality. From the ILP formulation, we derive two new pseudopolynomial models for particular cases of the 2D_R_CG_SLOPP, which consider only two‐staged or one‐group patterns. Finally, as a specific solution method for the 2D_R_CG_SLOPP, we apply Benders decomposition to the proposed ILP formulation and develop a branch‐and‐Benders‐cut algorithm. All proposed approaches are evaluated through computational experiments using benchmark instances and compared with other formulations available in the literature. The results show that the new formulations are appropriate in scenarios characterized by few item types that are large with respect to the object's dimensions. 相似文献
14.
Susanne Heipcke Yves Colombani Cristina C. B. Cavalcante Cid C. de Souza 《Constraints》2000,5(4):415-422
In this paper we introducean optimisation problem extracted from an industrial application:the scheduling problem under labour constraints. After givinga short summary of the origins of this problem and its mathematicalformulation, the different methods used for solving it (at leastpartially) are briefly described. In the last part, we presenta set of 25 instances of different sizes for benchmark purposes.So far, only 5 of these test instances have been solved to optimality,the others remaining open. 相似文献
15.
为解决自动化码头岸桥、AGV、场桥三个资源协同调度中AGV的路口碰撞问题,考虑任务分配、AGV的避碰约束,建立一个所有任务最大完工时间最小化为目标的混合整数规划模型.通过设置路口的相容和冲突相位,使处于相容相位的AGV可以同时通过.对考虑避碰规则和不考虑避碰规则的实验数组进行分析,比较其解的优劣性.实验结果表明在考虑避... 相似文献
16.
This paper studies a nurse scheduling problem of assigning a set of nurses to surgeries scheduled on each workday in an operating room (OR) suite. This problem plays a decisive role in utilizing nurses efficiently, which is of paramount importance for OR suites to provide high-quality service at ever reduced cost. Due to significant uncertainty in surgery durations, designing schedules that achieve high nurse efficiency is complicated by the competing objective of ensuring on-time starts of surgeries. For trading off between the two performance criteria, we formulate the problem as a mixed integer programming (MIP) model with explicit probability modeling of uncertainty. We are concerned about improving nurse efficiency in terms of overtime and idle time of nurses while mastering the risk of delay of surgeries. The MIP model is applied in a large size Chinese hospital, and the results are compared with the actual performance of the OR suite. The comparisons reveal that through examining the trade-off between the performance criteria, important nurse efficiency improvements can be achieved with good on-time start performance. Moreover, the applicability of the MIP model in various problem settings is also investigated. 相似文献
17.
文中提出三种新方法来解决汽车装配车间生产计划与调度的同时优化问题.首先将汽车装配线简化为一个Flow shop问题,并建立其混合整数规划模型,以求得使各装配工位的准备成本和空闲时间尽可能少并尽可能满足产品需求的粗生产计划.然后在粗生产计划的基础上考虑装配线的细节,用Tabu搜索法与快速调度仿真相结合的三种不同启发式算法使生产计划与调度同时得到优化,并给出了三种算法的复杂性.大量算例的比较研究表明了这些算法的有效性和适用性. 相似文献
18.
针对烘干窑生产周期长、成本高的问题,为提高其生产效率,缩短生产周期,对烘干窑的生产调度进行了优化,描述了一个现实中存在的烘干窑调度问题,提出了一种改进的融入了回溯思想的禁忌搜索算法,并给出了算法优化前后的生产计划比较。实际应用结果显示,该算法能有效地缩短生产周期,减少生产成本,提高设备利用率和合同准时率。 相似文献
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20.
This study considers a production lot sizing and scheduling problem in the brewery industry. The underlying manufacturing process can be basically divided into two main production stages: preparing the liquids including fermentation and maturation inside the fermentation tanks; and bottling the liquids on the filling lines, making products of different liquids and sizes. This problem differs from other problems in beverage industries due to the relatively long lead times required for the fermentation and maturation processes and because the “ready” liquid can remain in the tanks for some time before being bottled. The main planning challenge is to synchronize the two stages (considering the possibility of a “ready” liquid staying in the tank until bottling), as the production bottlenecks may alternate between these stages during the planning horizon. This study presents a novel mixed integer programming model that represents the problem appropriately and integrates both stages. In order to solve real-world problem instances, MIP-based heuristics are developed, which explore the model structure. The results show that the model is able to comprise the problem requirements and the heuristics produce relatively good-quality solutions. 相似文献