Showing papers on "Flow shop scheduling published in 2020"

A Knowledge-Based Cooperative Algorithm for Energy-Efficient Scheduling of Distributed Flow-Shop

Abstract: Facing increasingly serious ecological problems, sustainable development and green manufacturing have attracted much attention. Meanwhile, with the development of globalization, distributed manufacturing is becoming widespread. This paper addresses an energy-efficient scheduling of the distributed permutation flow-shop (EEDPFSP) with the criteria of minimizing both makespan and total energy consumption. Considering the distributed and multiobjective optimization complexity, a knowledge-based cooperative algorithm (KCA) is proposed to solve the EEDPFSP. First, a cooperative initialization scheme is presented with both extended energy-efficient Nawaz–Enscore–Ham heuristic and slowest allowable speed rule that are specially designed to produce good initial solutions with certain diversity. Second, several properties of the nondominated solutions are investigated based on the characteristics of the bi-objective problem, which are used to develop the knowledge-based search operators. Third, a cooperative search strategy of multiple operators is designed for the solutions with different characteristics to tradeoff two objectives. Fourth, a knowledge-based local intensification is used for exploiting better nondominated solutions sufficiently. Moreover, an energy saving method based on the critical path is used to further improve the performance. The effect of parameter setting on the KCA is investigated with the Taguchi method of design-of-experiment. Extensive computational tests and comparisons are carried out, which verify the effectiveness of the special designs of the KCA in solving the EEDPFSP.

Fuzzy Mathematical Programming and Self-Adaptive Artificial Fish Swarm Algorithm for Just-in-Time Energy-Aware Flow Shop Scheduling Problem With Outsourcing Option

Abstract: Flow shop scheduling (FSS) problem constitutes a major part of production planning in every manufacturing organization. It aims at determining the optimal sequence of processing jobs on available machines within a given customer order. In this article, a novel biobjective mixed-integer linear programming (MILP) model is proposed for FSS with an outsourcing option and just-in-time delivery in order to simultaneously minimize the total cost of the production system and total energy consumption. Each job is considered to be either scheduled in-house or to be outsourced to one of the possible subcontractors. To efficiently solve the problem, a hybrid technique is proposed based on an interactive fuzzy solution technique and a self-adaptive artificial fish swarm algorithm (SAAFSA). The proposed model is treated as a single objective MILP using a multiobjective fuzzy mathematical programming technique based on the ϵ-constraint, and SAAFSA is then applied to provide Pareto optimal solutions. The obtained results demonstrate the usefulness of the suggested methodology and high efficiency of the algorithm in comparison with CPLEX solver in different problem instances. Finally, a sensitivity analysis is implemented on the main parameters to study the behavior of the objectives according to the real-world conditions.

Hybrid Artificial Bee Colony Algorithm for a Parallel Batching Distributed Flow-Shop Problem With Deteriorating Jobs

Abstract: In this article, we propose a hybrid artificial bee colony (ABC) algorithm to solve a parallel batching distributed flow-shop problem (DFSP) with deteriorating jobs. In the considered problem, there are two stages as follows: 1) in the first stage, a DFSP is studied and 2) after the first stage has been completed, each job is transferred and assembled in the second stage, where the parallel batching constraint is investigated. In the two stages, the deteriorating job constraint is considered. In the proposed algorithm, first, two types of problem-specific heuristics are proposed, namely, the batch assignment and the right-shifting heuristics, which can substantially improve the makespan. Next, the encoding and decoding approaches are developed according to the problem constraints and objectives. Five types of local search operators are designed for the distributed flow shop and parallel batching stages. In addition, a novel scout bee heuristic that considers the useful information that is collected by the global and local best solutions is investigated, which can enhance searching performance. Finally, based on several well-known benchmarks and realistic industrial instances and via comprehensive computational comparison and statistical analysis, the highly effective performance of the proposed algorithm is favorably compared against several algorithms in terms of both solution quality and population diversity.

Scheduling Dual-Objective Stochastic Hybrid Flow Shop With Deteriorating Jobs via Bi-Population Evolutionary Algorithm

Abstract: Hybrid flow shop scheduling problems have gained an increasing attention in recent years because of its wide applications in real-world production systems. Most of the prior studies assume that the processing time of jobs is deterministic and constant. In practice, jobs’ processing time is usually difficult to be exactly known in advance and can be influenced by many factors, e.g., machines’ abrasion and jobs’ feature, thereby leading to their uncertain and variable processing time. In this paper, a dual-objective stochastic hybrid flow shop deteriorating scheduling problem is presented with the goal to minimize makespan and total tardiness. In the formulated problem, the normal processing time of jobs follows a known stochastic distribution, and their actual processing time is a linear function of their start time. In order to solve it effectively, this paper develops a hybrid multiobjective optimization algorithm that maintains two populations executing the global search in the whole solution space and the local search in promising regions, respectively. An information sharing mechanism and resource allocating method are designed to enhance its exploration and exploitation ability. The simulation experiments are carried out on a set of instances, and several classical algorithms are chosen as its peers for comparison. The results demonstrate that the proposed algorithm has a great advantage in dealing with the investigated problem.

A Three-Stage Multiobjective Approach Based on Decomposition for an Energy-Efficient Hybrid Flow Shop Scheduling Problem

Abstract: This paper investigates an energy-efficient hybrid flowshop scheduling problem with the consideration of machines with different energy usage ratios, sequence-dependent setups, and machine-to-machine transportation operations. To minimize the makespan and total energy consumption simultaneously, a mixed-integer linear programming (MILP) model is developed. To solve this problem, a three-stage multiobjective approach based on decomposition (TMOA/D) is suggested, in which each solution is bound with a main weight vector and a set of its neighbors. Accordingly, a variable direction strategy is developed to ensure each solution along its main direction is thoroughly exploited and can jump to the neighboring directions using a proximity principle. To ensure an active schedule of arranging jobs to machines, a two-level solution representation is employed. In the first phase, each solution attempts to improve itself along its current weight vector through a developed neighborhood-based local search. In the second phase, the promising solutions are selected through the technique for order preference by similarity to an ideal solution. Then, they attempt to update themselves with a proposed global replacement strategy via incorporation with their closing solutions. In the third phase, a solution conducts a large perturbation when it goes through all its assigned weight vectors. Extensive experiments are conducted to test the performance of TMOA/D, and the results demonstrate that TMOA/D has a very competitive performance.

Modeling and multi-neighborhood iterated greedy algorithm for distributed hybrid flow shop scheduling problem

Abstract: As economic globalization, large manufacturing enterprises build production centers in different places to maximize profit. Therefore, scheduling problems among multiple production centers should be considered. This paper studies a distributed hybrid flow shop scheduling problem (DHFSP) with makespan criterion, which combines the characteristic of distributed flow shop scheduling and parallel machine scheduling. In the DHFSP, a set of jobs are assigned into a set of identical factories to process. Each job needs to be through same route with a set of stages, and each stage has several machines in parallel and at least one of stage has more than one machine. For solving the DHFSP, this paper proposes two algorithms: DNEH with smallest-medium rule and multi-neighborhood iterated greedy algorithm. The DNEH with smallest-medium rule constructive heuristic first generates a seed sequence by decomposition and smallest-medium rule, and then uses a greedy iteration to assign jobs to factories. In the iterated greedy algorithm, a multi-search construction is proposed, which applies the greedy insertion to the factory again after inserting a new job. Then, a multi-neighborhood local search is utilized to enhance local search ability. The proposed algorithms are evaluated by a comprehensive comparison, and the experimental results demonstrate that the proposed algorithms are very competitive for solving the DHFSP.

Energy-efficient flexible flow shop scheduling with worker flexibility

Abstract: The classical flexible flow shop scheduling problem (FFSP) only considers machine flexibility. Thus far, the relevant literature has not studied FFSPs with worker flexibility, which is widely seen in practical manufacturing systems. Worker flexibility may greatly affect production efficiency and productivity. Furthermore, with the increase of environmental pollution and energy consumption, manufacturers require innovative methods to improve energy efficiency. In this paper, we propose an energy-efficient FFSP with worker flexibility (EFFSPW), in which the flexibility of machines and workers as well as the processing time, energy consumption and worker cost related factors are considered simultaneously. A hybrid evolutionary algorithm (HEA) is then presented to solve the proposed EFFSPW, where some effective operators and a new variable neighborhood search approach are designed. Comprehensive experiments including 54 benchmark instances of the EFFSPW are carried out, and Taguchi analysis is used to determine the best combination of key parameters for the HEA. Experimental results show that the proposed HEA can obtain better solutions for most of these benchmark instances compared to two other well-known algorithms, demonstrating its superior performance in terms of both solution quality and computational efficiency.

Hybrid enhanced discrete fruit fly optimization algorithm for scheduling blocking flow-shop in distributed environment

Abstract: Scheduling in distributed production environments is becoming widespread in recent years due to the increasing advantages of multi-factory manufacture. This paper investigates the distributed blocking flow-shop scheduling problem (DBFSP) with the objective of minimizing the makespan. To solve this problem, a hybrid enhanced discrete fruit fly optimization algorithm (HEDFOA) is proposed. In the proposed algorithm, an effective constructive heuristic is developed based on a new assignment rule of jobs and an insertion-based improvement procedure to initialize the common central location of all fruit fly swarms. In the smell-based foraging, an effective insertion-based neighborhood operator is designed for exploration in global scope. In the vision-based foraging, a local search is embedded to intensify the exploitation ability of algorithm in local region. Meanwhile, a simulated annealing-like acceptance criterion is employed to help algorithm escape from the local optimum. Finally, an extensive computational experiment is conducted. Experimental results show that the proposed HEDFOA is more effective than the existing state-of-the-art methods. Furthermore, 516 best known solutions out of 720 benchmark instances are also updated.

A cooperative coevolution algorithm for multi-objective fuzzy distributed hybrid flow shop

Abstract: With consideration of uncertainty in the distributed manufacturing systems, this paper addresses a multi-objective fuzzy distributed hybrid flow shop scheduling problem with fuzzy processing times and fuzzy due dates. To optimize the fuzzy total tardiness and robustness simultaneously, a cooperative coevolution algorithm with problem-specific strategies is proposed by reasonably combining the estimation of distribution algorithm (EDA) and the iterated greedy (IG) search. In the EDA-mode search, a problem-specific probability model is established to reduce the solution space and a sample mechanism is proposed to generate new individuals. To enhance exploitation, a specific local search is designed to improve performance of non-dominated solutions. Moreover, destruction and reconstruction methods in the IG-mode search are employed for further exploiting better solutions. To balance exploration and exploitation capabilities, a cooperation scheme for mode switching is designed based on the information entropy and the diversity of elite solutions. The effect of the key parameters on the performances of the proposed algorithm is investigated by Taguchi design of experiment method. Comparative results and statistical analysis demonstrate the effectiveness of the proposed algorithm in solving the problem.

An energy-efficient two-stage hybrid flow shop scheduling problem in a glass production

Abstract: Energy-efficient scheduling is highly necessary for energy-intensive industries, such as glass, mould or chemical production. Inspired by a real-world glass-ceramics production process, this paper investigates a bi-criteria energy-efficient two-stage hybrid flow shop scheduling problem, in which parallel machines with eligibility are at stage 1 and a batch machine is at stage 2. The performance measures considered are makespan and total energy consumption. Time-of-use (TOU) electricity prices and different states of machines (working, idle and turnoff) are integrated. To tackle this problem, a mixed integer programming (MIP) is formulated, based on which an augmented e-constraint (AUGMECON) method is adopted to obtain the exact Pareto front. A problem-tailored constructive heuristic method with local search strategy, a bi-objective tabu search algorithm and a bi-objective ant colony optimisation algorithm are developed to deal with medium- and large-scale problems. Extensive computational experiments are conducted, and a real-world case is solved. The results show effectiveness of the proposed methods, in particular the bi-objective tabu search.

Energy-efficient distributed permutation flow shop scheduling problem using a multi-objective whale swarm algorithm

Abstract: Production scheduling is of great significance in improving production effectiveness while the energy-efficient problem is one of most concerned problems for researchers and manufacturers. Thus, this study investigates the energy-efficient distributed permutation flow shop scheduling problem (DPFSP) with the objectives of makespan and energy consumption. The DPFSP is an extension of permutation flow shop problem (PFSP) considering a set of identical factories. This paper presents a multi-objective mixed integer programming model based on the three sub-problems: allocating jobs among factories, scheduling the jobs in each factory and determining speed upon each job. A multi-objective whale swarm algorithm (MOWSA) is proposed to solve this energy-efficient DPFSP. A new problem-dependent local search is developed to improve the exploitation capability of MOWSA. Moreover, the updating exploitation mechanism is presented to enhance energy efficiency without affecting production efficiency. Finally, the extensive comparison experiments are designed to demonstrate the effectiveness of proposed MOWSA, problem-dependent local search and updating exploitation mechanism. The results indicate the effectiveness of MOWSA and the superior performance over NSGA-II, SPEA2, PAES and MDEA, and also demonstrate that the proposed algorithm can significantly reduce the energy consumption compared with other algorithms.

Energy-efficient no-wait permutation flow shop scheduling by adaptive multi-objective variable neighborhood search

Abstract: This paper considers an energy-efficient no-wait permutation flow shop scheduling problem to minimize makespan and total energy consumption, simultaneously. The processing speeds of machines can be dynamically adjusted for different jobs. In general, lower processing speeds require less energy consumption but result in longer processing times, while higher speeds take the opposite effect. To reach the Pareto front of the problem, we propose an adaptive multi-objective variable neighborhood search (AM-VNS) algorithm. Specifically, we first design two basic speed adjusting heuristics which can reduce the energy consumption of a given solution without worsening its makespan. Two widely used neighborhood-generating operations, i.e., insertion and swap, are adapted and integrated into the variable neighborhood descent phase. With respect to their executing order, two variable neighborhood descent structures can be designed. We adopt an adaptive mechanism to dynamically determine which structure will be selected to handle the current solution. To further improve the performance of the algorithm, we develop a novel problem-specific shake procedure. We also introduce accelerating techniques to speed up the algorithm. Computational results show that the AM-VNS algorithm outperforms multi-objective evolutionary algorithms NSGA-II and SPEA-II.

A hybrid energy–Aware virtual machine placement algorithm for cloud environments

Abstract: The high energy consumption of cloud data centers presents a significant challenge from both economic and environmental perspectives. Server consolidation using virtualization technology is widely used to reduce the energy consumption rates of data centers. Efficient Virtual Machine Placement (VMP) plays an important role in server consolidation technology. VMP is an NP-hard problem for which optimal solutions are not possible, even for small-scale data centers. In this paper, a hybrid VMP algorithm is proposed based on another proposed improved permutation-based genetic algorithm and multidimensional resource-aware best fit allocation strategy. The proposed VMP algorithm aims to improve the energy consumption rate of cloud data centers through minimizing the number of active servers that host Virtual Machines (VMs). Additionally, the proposed VMP algorithm attempts to achieve balanced usage of the multidimensional resources (CPU, RAM, and Bandwidth) of active servers, which in turn, reduces resource wastage. The performance of both proposed algorithms are validated through intensive experiments. The obtained results show that the proposed improved permutation-based genetic algorithm outperforms several other permutation-based algorithms on two classical problems (the Traveling Salesman Problem and the Flow Shop Scheduling Problem) using various standard datasets. Additionally, this study shows that the proposed hybrid VMP algorithm has promising energy saving and resource wastage performance compared to other heuristics and metaheuristics. Moreover, this study reveals that the proposed VMP algorithm achieves a balanced usage of the multidimensional resources of active servers while others cannot.

Multi-objective genetic algorithm for energy-efficient hybrid flow shop scheduling with lot streaming

Abstract: Hybrid flow shop scheduling problems are encountered in many real-world manufacturing operations such as computer assembly, TFT-LCD module assembly, and solar cell manufacturing. Most research considers the scheduling problem in regard to time requirements and the steps needed to improve production efficiency. However, the increasing amount of carbon emissions worldwide is contributing to the worsening global warming problem. Many countries and international organizations have started to pay attention to this problem, even creating mechanisms to reduce carbon emissions. Furthermore, manufacturing enterprises are showing growing interest in realizing energy savings. Thus, the present research study focuses on reducing energy costs and completion time at the manufacturing-system level. This paper proposed a multi-objective mixed-integer programming for energy-efficient hybrid flow shop scheduling with lot streaming in order to minimize both the production makespan and electric power consumption. Due to a trade-off between these objectives and the computational complexity of the proposed multi-objective mixed-integer program, this study adopts the genetic algorithm (GA) to obtain approximate Pareto solutions more efficiently. In addition, a multi-objective energy efficiency scheduling algorithm is also developed to calculate the fitness values of each chromosome in GA.

More MILP models for hybrid flow shop scheduling problem and its extended problems

Abstract: With the rapid development of computer technology and related softwares for mathematical models, mathematical modelling of scheduling problems is receiving growing attention from researchers. In th...

Energy-efficient scheduling for multi-objective two-stage flow shop using a hybrid ant colony optimisation algorithm

Abstract: Reducing energy costs has become an important concern for sustainable manufacturing systems, owing to concern for the environment. We present a multi-objective hybrid ant colony optimisation (MHACO...

Effective heuristics and metaheuristics for the distributed fuzzy blocking flow-shop scheduling problem

Abstract: In consideration of the uncertainty of manufacturing system, this paper investigates a distributed fuzzy blocking flow-shop scheduling problem (DFBFSP) in which there are multiple homogeneous factories and each one is set as a flow shop with no intermediate buffers between any consecutive machines. The processing time is uncertain and represented by the fuzzy number. The objective is to minimize the fuzzy makespan among all factories. To address this problem, two constructive heuristics (i.e., INEH and DPFNEH) are firstly proposed based on the problem-specific knowledge and the NEH heuristic. The INEH employs the spread value of fuzzy processing time to generate the initial job sequence. The DPFNEH assigns the partial jobs to factories by reducing the total expected idle time and blocking time. Afterwards, two iterated greedy (IG) methods are presented in which the proposed constructive heuristic is employed to generate the initial solution with high quality. A novel plateau exploration-based local search is incorporated to enhance the quality of solutions. To keep the search vitality, an improved acceptance criterion based on the fuzzy characteristic is designed to avoid falling into the local optimum. Finally, a comprehensive computational experiment and comparisons with the state-of-the-art methods in the literature are conducted based on an extended benchmark set and a new evaluation indicator. The results show that the proposed constructive heuristics and IG methods can effectively and efficiently solve the considered problem.

A Bi-Population Cooperative Memetic Algorithm for Distributed Hybrid Flow-Shop Scheduling

Abstract: In the context of globalization and decentralized economies, the distributed manufacturing and scheduling systems have become emerging in large enterprises. This article addresses the distributed hybrid flow-shop scheduling problem (DHFSP) with heterogeneous factories to minimize makespan. Different from single-factory scheduling problem, DHFSP contains several strongly coupled sub-problems, i.e., factory assignment of jobs and the job sequencing in each hybrid flow-shop. In this article, we present a mixed integer linear programming model for the DHFSP and make a first attempt to propose a bi-population cooperative memetic algorithm (BCMA) for solving such a strongly NP-hard problem. The proposed optimization framework comprises collaborative initialization, bi-population cooperation and local intensification. To generate diverse solutions with small makespan, two knowledge-based heuristics are designed for collaborative initialization by utilizing the lower bound of the problem and the historic information of elite solutions during search process. To balance exploration and exploitation, two populations are evolved in a cooperative way. To further enhance the optimization capability, intensification search with multiple problem-specific operators is incorporated. The effect of parameter setting is investigated and extensive computational tests are carried out. The comparative results show that the BCMA is more effective than both the Math solver Gurobi and the existing iterated greedy algorithm, and the effectiveness of each specific design is also verified in solving DHFSP.

Stochastic optimization of two-machine flow shop robotic cells with controllable inspection times: From theory toward practice

Abstract: This paper considers the stochastic scheduling of a two-machine flow shop robotic cell with controllable inspection times. The inspection here is performed by a multi-function robot which can inspect identical parts with two alternatives for the inspection strategy: either at the back of the upstream machine or in transit between upstream and downstream machines. A characteristic of the inspection process is that its time is changed by altering the inspection cost. If the inspection time is reduced, more failures in parts may result regardless of when failures are identified. The challenge is therefore to find a suitable trade-off between inspection time and internal and external quality costs to increase reliability benefits. Initially, we complete a structural analysis of costs of quality and partial cycles, and then consider a simultaneous analysis of them. Then, through a sensitivity analysis, an epsilon-constraint method is used to find useful upper bounds on costs of quality and partial cycle times. The outcomes of the research are (i) an integrated framework for designing robotic cells with different levels of quality: low (e.g., disassembly industries), medium (e.g., automotive industries), and high (e.g., aerospace industries); and (ii) a sensitivity analysis for studying the impact of inspection strategies to assist production and quality managers with decision-making processes in stochastic environments. Finally, we extend the analysis to show that the given framework can be generalized for subtle variations found in practical applications with regard to (i) the quality of the part and (ii) accuracy of the inspection process. Robotic cells with scrap consideration and robotic cells with decreasing failure rates of the inspection process are studied as examples of the former, and robotic cells with either convex cost function or discrete cost function are studied for the latter.

Effective Constructive Heuristic and Metaheuristic for the Distributed Assembly Blocking Flow-shop Scheduling Problem

Abstract: Scheduling in distributed production system has become an active research field in recent years. This paper investigates the distributed assembly blocking flow-shop scheduling problem (DABFSP), which consists of two stages: production and assembly. The first stage is processing jobs in several identical factories. Each factory has a series of machines no intermediate buffers existing between adjacent ones. The second stage assembles the processed jobs into the final products through a single machine. The objective is to minimize the maximum completion time or makespan of all products. To address this problem, a constructive heuristic is proposed based on a new assignment rule of jobs and a product-based insertion procedure. Afterwards, an iterated local search (ILS) is presented, which integrates an integrated encoding scheme, a multi-type perturbation procedure containing four kinds of perturbed operators based on problem-specific knowledge and a critical-job-based variable neighborhood search. Finally, a comprehensive computational experiment and comparisons with the closely related and well performing methods in the literature are carried out. The experimental and comparison results show that the proposed constructive heuristic and ILS can solve the DABFSP effectively and efficiently.