Showing papers on "Job shop published in 2002"
TL;DR: This paper proposes a Pareto approach based on the hybridization of fuzzy logic (FL) and evolutionary algorithms (EAs) to solve the flexible job-shop scheduling problem (FJSP).
499 citations
TL;DR: It is shown that several key properties, used to design heuristic procedures, do not hold in the blocking and no-wait cases, while some of the most effective ideas used to develop branch and bound algorithms can be easily extended.
448 citations
TL;DR: In this paper, a modified shifting bottleneck heuristic is developed for minimizing the total weighted tardiness in a semiconductor wafer fabrication facility, which is characterized by re-entrant or re-circulating product flow through a number of different tool groups (one or more machines operating in parallel).
Abstract: Increases in the demand for integrated circuits have highlighted the importance of meeting customer quality and on-time delivery expectations in the semiconductor industry A modified shifting bottleneck heuristic is developed for minimizing the total weighted tardiness in a semiconductor wafer fabrication facility This ‘complex’ job shop is characterized by re-entrant or re-circulating product flow through a number of different tool groups (one or more machines operating in parallel) These tool groups typically contain batching machines, as well as machines that are subject to sequence-dependent setups The disjunctive graph of the complex job shop is presented, along with a description of the proposed heuristic Preliminary results indicate the heuristic's potential for promoting on-time deliveries by semiconductor manufacturers for their customers' orders Copyright © 2002 John Wiley & Sons, Ltd
179 citations
TL;DR: An extension of the job shop models that are used in the theoretical studies is proposed that can explain the differences between the results of theoretical studies and empirical studies into the effects of workload control on performance and shows that, under certain conditions, without workload control the shop performance can become unstable.
Abstract: In this paper we propose an extension of the job shop models that are used in the theoretical studies, that can explain the differences between the results of theoretical studies and empirical studies into the effects of workload control on performance. The extension assumes that the workload level affects the effective processing times in a shop and is based on the results of empirical research on the relationship between workload and shop performance. Using computer simulation we investigate the effects of workload based work order release on the shop performance under the new job shop model. The simulation results confirm the effect of workload control on shop performance found in empirical studies, and show that, under certain conditions, without workload control the shop performance can become unstable
107 citations
TL;DR: This paper addresses job-shop scheduling problems with deteriorating jobs, i.e. jobs whose processing times are an increasing function of their starting time, and proves NP-hardness of the job- shop problem even for two machines.
103 citations
TL;DR: The theoretical and practical knowledge regarding the WLC concept are brought together and a review and classification of strengths and weaknesses reported from analytical research and the extensions that have been developed based on practical experiences are discussed.
Abstract: Workload control (WLC) has been elaborated in the early 1980s to a hierarchical production control concept for job shop manufacturing. In the 1990s the analytical research at the University of Groningen focused on assessing the strengths and weaknesses of this concept and on developing alternatives. Research at the University of Hannover focused on improving the practical applicability of the WLC concept. While the practical experiences confirm the strengths of the WLC concept, some extensions of the basic concept have been developed which may overcome some weaknesses suggested in literature. This paper aims at bringing the theoretical and practical knowledge regarding the WLC concept together. It gives a review and classification of strengths and weaknesses reported from analytical research and it discusses the extensions that have been developed based on practical experiences.
96 citations
TL;DR: The ANN-based simulations were able to fairly capture the underlying relationship between jobs' machine sequences and their resulting average flowtimes, which proves that ANNs are a viable tool for stochastic simulation metamodeling.
86 citations
08 Apr 2002
TL;DR: This paper shows how the problem of job-shop scheduling where the jobs are preemptible can be modeled naturally as a shortest path problem defined on an extension of timed automata, namely stopwatch automata where some of the clocks might be freezed at certain states.
Abstract: In this paper we show how the problem of job-shop scheduling where the jobs are preemptible can be modeled naturally as a shortest path problem defined on an extension of timed automata, namely stopwatch automata where some of the clocks might be freezed at certain states. Although general verification problems on stopwatch automata are known to be undecidable, we show that due to particular properties of optimal schedules, the shortest path in the automaton belongs to a finite subset of the set of acyclic paths and hence the problem is solvable. We present several algorithms and heuristics for finding the shortest paths in such automata and test their implementation on numerous benchmark examples.
83 citations
TL;DR: In this article, an enhanced genetic algorithm is proposed for job shop scheduling, where an effective crossover operation for operation-based representation is used to guarantee the feasibility of the solutions, which are decoded into active schedules during the search process.
Abstract: As a class of typical production scheduling problems, job shop scheduling is one of the strongly NP-complete combinatorial optimisation problems, for which an enhanced genetic algorithm is proposed in this paper. An effective crossover operation for operation-based representation is used to guarantee the feasibility of the solutions, which are decoded into active schedules during the search process. The classical mutation operator is replaced by the metropolis sample process of simulated annealing with a probabilistic jumping property, to enhance the neighbourhood search and to avoid premature convergence with controllable deteriorating probability, as well as avoiding the difficulty of choosing the mutation rate. Multiple state generators are applied in a hybrid way to enhance the exploring potential and to enrich the diversity of neighbourhoods. Simulation results demonstrate the effectiveness of the proposed algorithm, whose optimisation performance is markedly superior to that of a simple genetic algorithm and simulated annealing and is comparable to the best result reported in the literature.
82 citations
TL;DR: In this paper, a mixed integer program model of the problem is presented, along with a local search scheme that utilizes a property identified to reduce computation time and establishes a performance bound.
82 citations
TL;DR: In this article, a comprehensive review of the literature on reactive recovery of job shop schedules is presented, and further research work in this area is proposed to further improve the reactive recovery.
Abstract: In the recent past, a great deal of time and effort has been devoted to the development of job shop schedules. These schedules are able to cope with the dynamic and stochastic nature of job shops that consist of the uncertainties both at the planning stages and on on-line execution. Deviations from predictive schedules occur when the job shop experiences both external disturbances (e.g. urgent job arrivals) and internal disruptions (e.g. machine breakdowns). To avoid complete rescheduling of the job shop a repair and recovery strategy for the schedule becomes essential. This paper provides a comprehensive review of the literature on the reactive recovery of job shop schedules and proposes further research work in this area.
06 Oct 2002
TL;DR: The problem considered in this paper is an important extension of the classical job shop scheduling problem, where the same operation can be performed on more than one machine.
Abstract: The problem considered in this paper is an important extension of the classical job shop scheduling problem, where the same operation can be performed on more than one machine. The problem is to assign each operation to a machine and to sequence the operations on the machines, such that the makespan of a set of jobs Is minimized. A generalized job shop problem is defined in detail. A variation of the simulated annealing method is proposed and computational results are provided.
TL;DR: In this article, a graph representation that looks at specific characteristics of production scheduling in chemical processes is proposed, where the nodes represent the production tasks, the arcs of the precedence relationships among them.
Abstract: The production scheduling of multipurpose batch plants is considered. A novel graph representation that looks at the specific characteristics of production scheduling in chemical processes is proposed. In these graphs, the nodes represent the production tasks, the arcs of the precedence relationships among them. The representation is flexible enough to consider a wide variety of production structures, including complex recipes. Both nonintermediate storage (NIS) and unlimited intermediate storage (UIS) transfer policies can be considered simply by choosing the appropriate precedence relationships. This representation provides the opportunity of incorporating highly efficient graph algorithms together with an appropriate branch-and-bound algorithm for solving multipurpose scheduling problems. The efficiency of the proposed method is established by solving examples and a complex case study.
TL;DR: Numerical results show that the auction-based approach outperforms the distributed dispatching approaches and can be used to create schedules for a wide range of scheduling objectives.
Abstract: Developments in computing and communication technology coupled with the inability to address real-time issues in scheduling algorithms based on central control, has led to an interest in solving the problem of a distributed decision-making environment. This paper presents a new job shop formulation that schedules jobs using auctions for distributing control. A theoretical basis is presented for problem decomposition, bid construction, and bid evaluation for the auction using standard mathematical programming tools. Numerical results show that the auction-based approach outperforms the distributed dispatching approaches and can be used to create schedules for a wide range of scheduling objectives.
TL;DR: This work considers a single-machine scheduling problem which arises as a subproblem in a job-shop environment where the jobs have to be transported between the machines by a single transport robot and presents a local search algorithm where an appropriate neighborhood structure is defined using problem-specific properties.
TL;DR: In this article, a general class of multiprocessor shop scheduling problems, preemptive or non-preemptive, with precedence constraints between operations, with job or operation release dates, and with a class of objective functions including weighted sums of job, operations and stage completion times, are considered.
Abstract: We consider a general class of multiprocessor shop scheduling problems, preemptive or non-preemptive, with precedence constraints between operations, with job or operation release dates, and with a class of objective functions including weighted sums of job, operations and stage completion times. We present a general approximation method combining a linear programming relaxation in the operation completion times, with any algorithm for the makespan version of these problems without release dates. If the latter produces a schedule with makespan no larger than ρ times the ‘trivial lower bound’ consisting of the largest of all stage average loads (or ‘congestion’) and job lengths (or ‘dilation’), then our method produces a feasible schedule with minsum objective no larger than 2eρ times the optimum where 2e≈5.44. This leads, in particular, to a polynomial time algorithm with polylogarithmic performance guarantee for the minsum multiprocessor dag-shop problem J(P)∣rij, dagj∣ΣSwSCS where ΣSwSCS is a general minsum objective including weighted sum of operation and job completion times, stages makespans and others, whereas the best known earlier performance guarantees were O(m) (where m is the number of stages) for the special cases J∥ΣCj, F(P)∣rj∣ ΣwjCj and O∥ΣCj. We also obtain a O(1) performance guarantee for the acyclic job shop problem J∣pij=1, acyclic-dagj∣ΣSwSCS with unit processing times and weighted sum of operation (or job) completion time objective. Our results extend to a broad class of minsum objective functions including some convex objectives related to load balancing. We then present an improved 5.83-approximation algorithm for the open shop problem O∣rj∣ΣwjCj with total weighted job completion time objective. We conclude with a very simple method which yields O(m)-approximation algorithms for various job shop problems (preemptive, non-preemptive, and no-wait) with m single-processor stages and total weighted job completion time objective. Copyright © 2002 John Wiley & Sons, Ltd.
TL;DR: In this paper, the performances of three workload limiting policies are analysed, and the following are the three objectives: assessing whether the method of workload limiting affects the performance of Order Review and Release strategies; investigating the performances when the mix imbalance changes; evaluating the robustness of the workload limiting methods considered.
Abstract: The performances of three workload limiting policies are analysed, and the following are the three objectives: (i) assessing whether the method of workload limiting affects the performances of Order Review and Release strategies; (ii) investigating the performances of the workload limiting methods when the mix imbalance changes; (iii) evaluating the robustness of the workload limiting methods considered. The methodological pattern followed required a simulation model of a dynamic job shop system and all the workload limiting methods are tested by resorting to a fractional factorial experimental design with repetitions. Results coming from simulation campaign show that the 'upper bound only' method is the best performer. Furthermore three different mix imbalance levels have been tested, showing that 'workload balancing' method allows closer performances to those of the 'upper bound only'. Finally 'workload balancing' is proven to be the most robust, but not all the results are statistically significant for...
TL;DR: A new flowtime estimation method is proposed that utilizes the detailed job, shop and route information for operations of jobs as well as the machine imbalance information and is quite robust to changing shop conditions.
Abstract: In the scheduling literature, estimation of job flowtimes has been an important issue since the late 1960s. The previous studies focus on the problem in the context of due date assignment and develop methods using aggregate information in the estimation process. In this study, we propose a new flowtime estimation method that utilizes the detailed job, shop and route information for operations of jobs as well as the machine imbalance information. This type of information is now available in computer-integrated manufacturing systems. The performance of the proposed method is measured by computer simulation under various experimental conditions. It is compared with the existing flowtime estimation methods for a wide variety of performance measures. The results indicate that the proposed method outperforms all the other flowtime estimation methods. Moreover, it is quite robust to changing shop conditions (i.e., machine breakdowns, arrival rate and processing time variations, etc.). A comprehensive bibliography is also provided in the paper.
TL;DR: FLC is used to adaptively regulate the crossover ratio and the mutation ratio of the proposed algorithm and various experiments show that the results of pro-fGA outperform those ofpro-GA.
TL;DR: In this article, the authors demonstrate the usefulness of employing TOC-based global performance measures to make operational decisions (e.g., product mix, continuous improvement, inventory management, production planning and scheduling) to strengthen the internal supply chain in a relatively complex manufacturing environment.
Abstract: Theory of constraints (TOC) views a company as a set of interdependent processes working in harmony to achieve the profit goal of the company as a whole, and thus it emphasizes total system performance over localized measures to guide operational decisions. This paper demonstrates the usefulness of employing TOCbased global performance measures to make operational-decisions (e.g. product mix, continuous improvement, inventory management, production planning and scheduling) to strengthen the internal supply chain in a relatively complex manufacturing environment, i.e. a job shop. An ARENA-based simulation model is presented and a number of scenarios are discussed that provide insights regarding the characteristic features of TOC, such as goals and necessary conditions, performance measures, five-focusing steps for continuous improvement, and drumbuffer-rope scheduling. These insights will assist managers in making important decisions regarding approaches to successful TOC implementations, and will provide ...
TL;DR: The results provide a map of the computational complexity of cycle time minimization problems that is analogous to that in the literature for makespan problems, and establish that some generalizations of this problem are unary NP-complete.
Abstract: We consider scheduling problems for shops in which a job set is manufactured repetitively. Jobs are scheduled to minimize the cycle time of the job set, which is equivalent to maximizing the throughput rate. We characterize the complexity of the scheduling problem for several types of job shops. Polynomial time algorithms are presented for open shops, and for job shops where each job has at most two operations. When there are two machines and the maximum number of operations of any job is a constant k⩾3, the recognition version of the job shop problem is shown to be binary NP-complete. We describe a pseudopolynomial time algorithm for a special case of the problem when k=3. We also establish that some generalizations of this problem are unary NP-complete. One consequence of these results is that the recognition version of the two machine job shop makespan problem with at most five operations per job is unary NP-complete. This resolves a question posed by Lenstra et al. (Ann. Discrete Math. 1977; 1: 343). More generally, our results provide a map of the computational complexity of cycle time minimization problems that is analogous to that in the literature for makespan problems. Copyright © 2002 John Wiley & Sons, Ltd.
01 Jun 2002
TL;DR: In this paper, the authors considered the job shop scheduling problem to minimize the total weighted tardiness with job-specific due dates and delay penalties, and a heuristic algorithm based on the tree search procedure was developed for solving the problem.
Abstract: This paper considers the job shop scheduling problem to minimize the total weighted tardiness with job-specific due dates and delay penalties, and a heuristic algorithm based on the tree search procedure is developed for solving the problem. A certain job shop scheduling to minimize the maximum tardiness subject to fixed sub-schedules is solved at each node of the search tree, and the successor nodes are generated, where the sub-schedules of the operations are fixed. Thus, a schedule is obtained at each node, and the sub-optimum solution is determined among the obtained schedules. Computational results on some 10 jobs and 10 machines problems and 15 jobs and 15 machines problems show that the proposed algorithm can find the sub-optimum solutions with a little computation time.
TL;DR: This paper describes how the job shop environment may be formulated as an open queueing network, and initial results suggest that treating each work station as an independent queueing system leads to significant under-estimation of the manufacturing lead times, even for such a simple manufacturing system.
TL;DR: Two methods, namely the branch and bound technique and a heuristic based on a multistage programming approach, have been applied to solve the chosen problem and data sets have been generated to compare these two methods in terms of quality of solution and demand on computational time.
Abstract: Many algorithms for cell formation have been developed for past three decades in cellular manufacturing. Some use binary data for cell formation and others use production data such as operation sequence, processing times,production volumes, etc. for cell formation. All these algorithms assume that the conversion of job shop to cellular manufacturing is performed comprehensively. (In other words, they assume that all the cells are formed at a time.) However, this is far from reality. In practice, cell formation is done incrementally, one after the other, rather than comprehensively. None of the algorithms developed so far addresses the issue of incremental cell formation. In this paper, the incremental cell formation problem is defined and various categories of problems are mentioned. One type of those categories is selected for solving. Two methods, namely the branch and bound technique and a heuristic based on a multistage programming approach, have been applied to solve the chosen problem. Data sets have been generated to compare these two methods in terms of quality of solution and demand on computational time. It has been found that the branch and bound technique gives a superior quality solution, but is computationally more demanding, where as heuristic based on a multistage programming approach is computationally far superior.
TL;DR: In this paper, a job shop scheduling procedure, known to provide near-optimal solutions to industrial-sized problems, is enhanced to include transportation elements in the fundamental model, and a lower bound calculation is compared to the procedure's solutions on a number of large-scale test problems.
Abstract: A procedure is developed for the simultaneous scheduling of multi-factory supply chains, including inter-factory transportation. A job-shop scheduling procedure, known to provide near-optimal solutions to industrial-sized problems, is enhanced to include transportation elements in the fundamental model. In order to demonstrate the quality of the solutions, a lower bound calculation is compared to the procedure's solutions on a number of large-scale test problems. The lower bound is an enhancement of the classic lower bound calculation for the N-job, M-machine job shop. The computational effort in scheduling is linear in the size of the problem, and high quality solutions to large-scale problems can be obtained in seconds.
TL;DR: This study shows that material requirements planning can be done more effectively in a job shop environment using a resource constrained project scheduling model and provides improved schedules with considerable reductions in inventory carrying costs.
Abstract: One of the most difficult tasks in a job shop manufacturing environment is to balance schedule and capacity in an ongoing basis. MRP systems are commonly used for scheduling, although their inability to deal with capacity constraints adequately is a severe drawback. In this study, we show that material requirements planning can be done more effectively in a job shop environment using a resource constrained project scheduling model. The proposed model augments MRP models by incorporating capacity constraints and using variable lead time lengths. The efficacy of this approach is tested on MRP systems by comparing the inventory carrying costs and resource allocation of the solutions obtained by the proposed model to those obtained by using a traditional MRP model. In general, it is concluded that the proposed model provides improved schedules with considerable reductions in inventory carrying costs.
TL;DR: In this article, the authors consider a cyclic job shop where some operations of an MPS instance are processed prior to some previous operations of the previous MPS instances and show that for a given processing sequence of the operations at each machine, under some conditions, an OCJS has a stable earliest starting schedule such that each operation starts as soon as its preceding operations are completed, the schedule repeats an identical timing pattern for each MPSinstance, and the cycle time is kept to be minimal.
Abstract: A cyclic shop is a production system that repeatedly produces identical sets of parts of multiple types, called minimal part sets (MPSs), in the same loading and processing sequence. A different part type may have a different machine visit sequence. We consider a version of cyclic job shop where some operations of an MPS instance are processed prior to some operations of the previous MPS instances. We call such a shop an overtaking cyclic job shop (OCJS). The overtaking degree can be specified by how many MPS instances the operations of an MPS instance can overtake. More overtaking results in more work-in-progress, but reduces the cycle time, in general. We prove that for a given processing sequence of the operations at each machine, under some conditions, an OCJS has a stable earliest starting schedule such that each operation starts as soon as its preceding operations are completed, the schedule repeats an identical timing pattern for each MPS instance, and the cycle time is kept to be minimal. To do these, we propose a specialized approach to analyzing steady states for an event graph model of an OCJS that has a cyclic structure, which can keep the MPS-based scheduling concept. Based on the steady-state results, we develop a mixed integer programming model for finding a processing sequence of the operations at each machine and the overtaking degrees, if necessary, that minimize the cycle time.
TL;DR: The main result is a (2 + e)- approximation algorithm for this problem that is a generalized version of the classical preemptive open shop problem with sum of weighted job completion times objective.
Patent•
27 Dec 2002TL;DR: In this article, the authors propose a serial processing environment where three different standalone processing apparatuses for different steps constitute the job shop environment, and two different serial processing apparatus constitute the flow shop environment.
Abstract: A flagship line 1 includes a job shop environment and a flow shop environment where three different standalone processing apparatuses for different steps constitute the job shop environment and two different serial processing apparatuses constitute the flow shop environment. One of the two serial processing apparatuses as a first serial processing apparatus 8 consists of a die bonder 5 , a clean cure unit 6 , and a wire bonder 7 and sequentially performs die bonding, clean cure and wire bonding. The other or second serial processing apparatus 13 consists of a marking unit 9 , a cutting unit 10 , a testing unit 11 , and a visual inspection unit 12 and sequentially performs marking, lead cutting, testing, and visual inspection. The three standalone processing apparatuses are a dicing apparatus 2 , a molding apparatus 4 , and a visual inspection apparatus 3 . This not only minimizes the possibility of a stagnant flow of workpieces between steps but also substantially shortens the overall processing time.
TL;DR: This paper considers problems of finding non-periodic and periodic schedules in a cycle shop which is a special case of a job shop but an extension of a flow shop and proposes a classification of cycle shops.
Abstract: This paper considers problems of finding non-periodic and periodic schedules in a cycle shop which is a special case of a job shop but an extension of a flow shop. The cycle shop means the machine environment where all jobs have to pass the machines over the same route like in a flow shop but some of the machines in the route can be met more than once. We propose a classification of cycle shops and show that recently studied reentrant flow shops, robotic flow shops, loop reentrant flow shops and V shops are special cases of cycle shops. Problems solvable in polynomial time, pseudopolynomial time, NP-hard problems and performance guarantee approximations are presented. Related earlier results are surveyed. Copyright © 2002 John Wiley & Sons, Ltd.