1,721,040 research outputs found
Capacity and resource allocation in flexible production networks by a game theory model
No full textIn many production applications, plants that produce multiple products with random demands share the required items among suppliers. The decision of how to allocate requests between suppliers to achieve the desired level of customer service is relevant to the efficiency of the production network. The literature highlighted how the long chain has the same level of performance as the full flexible network. This research proposes a decision model based on the game theory model to improve the performance of the production network. The model uses the Gale-Shapley algorithm with low computational complexity to share the demand among the suppliers. A simulation environment allows the evaluation of the proposed model in different conditions, and the model is compared to the dedicated, full flexibility, and long chain models. The numerical results show how the proposed model improves the efficiency of the production environment by keeping the number of connections with the supplier closer to the long chain model
Design model for assembly lines including fractional tasks and parallel workstations
No full textIn recent years, the use of robots and cobots allow to increase productivity and quality of products. Due to the higher investment, the robustness and efficiency of flow lines are crucial to reduce the throughput loss. The solution of installing buffers between stations increases costs and factory space. To improve the efficiency and robustness of assembly lines, the literature proposed some variants to the simple assembly line balancing problem. The introduction of fractional tasks and parallel workstations are two promising models proposed in recent works to reduce throughput loss caused by short failures. The potential of the two approaches has been studied individually, but no work has evaluated the integration of fractional and parallel tasks can further improve the efficiency of the production lines. This paper proposes a matheurstic method to design assembly lines integrating fractional tasks and parallel workstations. The approach proposed aims to reduce the computational complexity of the design of the assembly lines and provides a series of design alternatives. The simulation model tests the robustness of the design alternatives against short failures. The numerical results highlight how the proposed model improves the performance and the robustness of the assembly line when unforeseen events such as failures occur. The integration of fractional tasks and parallel tasks can improve the robustness against short failures. This benefit is relevant for robotic assembly lines, and the increasing use of cobots that are mainly used in the automotive, electronics sector, and metal machinery industries
Performance analysis of matrix-structured manufacturing systems compared to dedicated flow and reconfigurable manufacturing lines
No full textManufacturing systems encounter various unpredictable external and internal changes that diminish efficiency. These alterations in assembly systems, resulting in variations in processing times, failures, and multiple product types, often lead to issues such as starvation or blocking at workstations. Improving routing flexibility, as opposed to using fixed routing, can enhance the efficiency of assembly lines. A reconfigurable manufacturing system introduces limited routing flexibility, while a matrix-structured manufacturing system (MMS) incorporates complete routing flexibility. This research evaluates the performance of MMS configurations with different levels of flexibility and two allocation rules compared to reconfigurable manufacturing and dedicated systems. The simulation analysis conducted highlights the benefits of MMS compared to reconfigurable and dedicated systems in terms of performance measures and energy consumption. The numerical results emphasize the significant advantages of MMS for both production performance and energy consumption when the setup time accounts for approximately 10% of the average processing time of the tasks. This setup time enables the realization of benefits with a moderate level of machine flexibility within the MMS. However, when the setup time is higher, the reconfigurable system becomes a valid alternative to improve performance
Workload control order release with controllable processing time policies: an assessment by simulation
No full textWorkload Control is used in manufacturing systems to obtain more predictable throughput times and accurate delivery dates. The models proposed in the literature are typically focused on machines with fixed processing time. This study, therefore, uses simulation to investigate the performance of the Workload Control method with a controllable processing time of the machines. This research proposes four models to support the decisions on the time to reconfigure the machines and the number of machines reconfigured. The time decision follows two strategies as periodic and continuous, while the machines reconfigured can be all or two considering the workload. The combinations of these strategies lead to four models that are tested in different conditions of reconfiguration times and the number of bottlenecks. The results suggest as the proposed models allow to improve delivery time performance and a more uniform distribution of workload among the machines of the manufacturing systems
Evaluation of redundant configurations in assembly lines with fractional tasks
No full textAssembly lines with fractional tasks increase the throughput with a better workload balancing among the stations. The possibility to share tasks between two consecutive stations can also support the design of assembly lines with redundancies of the tasks. The redundancy of the tasks allows reacting to short failures or variations in processing time. This paper proposes a framework to support the design and control of redundancy assembly lines. The first problem concerns a modified mixed-integer linear programming model used for the fractional allocation assembly line problem to design redundancy assembly lines. Then, this research proposes control policies to manage the allocation of the tasks shared between two consecutive stations. Finally, the simulation evaluates the performance of the proposed methods to handle short failures and uncertain processing times. The numerical results show the potential improvements of the proposed methods with a limited number of redundancies. The main improvements concern the reduction of throughput time and work in process
Controllable processing times with limited resources and energy consumption in flow shops: an assessment by simulation
No full textIn production systems, the total energy available is a constraint due to energy costs or power consumption. The control of the processing time can affect the total energy consumed for the task performed. This paper proposes two control policies to change the processing time of stations that composes a flow line under resource consumption constraint in a production period. The first reduces the processing time of one station (centralized), while the second reduces the processing time of more stations (distributed). The introduction of an accumulator of the resources (such as a battery) can use any residual energy of a period in the following period. A multi-agent architecture has been developed to support the proposed models. This architecture decomposes the main problem into several sub-tasks, reducing the computational complexity and enabling the solution of larger and industrial problems. The simulation results highlight how the centralized approach works better when fewer resources are available, and the production line is unbalanced. On the other hand, the distributed model is more suitable for a balanced flow line. The introduction of an accumulator improves the performance of the centralized model compared to the distributed model
A dynamic adjusted aggregate load method to support workload control policies
No full textWorkload control mechanisms are widely studied in the literature for the control of job-shop systems. The control of these systems involves acceptance, order release and priority dispatching. At the release level, the workload norm controls the "enters" of the jobs; it is relevant how the aggregate workload is computed. Few works have studied new computation methods of the aggregate workload but use the adjusted aggregate workload proposed in the literature. This paper proposes a dynamically adjusted aggregate workload to improve the performance of the workload control mechanism in job-shop systems. The adjusted aggregate workload is updated when each part exits from a workstation; this means that the workload used to release the orders is related to the state of the job shop in real-time. Simulation is used to evaluate and compare the proposed model to the classical models proposed in the literature. The simulation experiments demonstrate improvement of performance and how the model proposed is robust under different manufacturing system conditions
Tasks Allocation Based on Fuzzy Rules in Fractional Assembly Line with Redundancy
No full textIn recent years, assembly line design methodologies have included the possibility of sharing tasks between stations. These approaches increase the throughput, improving the workload balance among the stations. Sharing operations can support the management of assembly lines with task redundancy. The redundancy of the tasks between two consecutive stations improves the robustness of the assembly line to unforeseen events. A control policy that allocates the shared tasks between two adjacent stations is crucial for the performance of the assembly line. This paper proposes a fuzzy approach to distributing the workload of the shared tasks between two consecutive stations. The fuzzy model allows for the distribution of the workload between the stations in a more gradual way. Simulations were conducted to allow for a performance evaluation with a model proposed in the literature. The results show how the fuzzy model improves all the performance measures evaluated; in particular, when the inter-arrival of the raw items is rather stable. In these conditions, the reduction of the average time and its standard deviation is about 50% to 80%, while the reduction of the work in process is about 60% to 90%. These benefits are obtained with a relevant increase of the variations of the average utilization of the stations
Comparison of Dynamic Decoupling Point and Dynamic Buffer Level for Flexible Flow Shops in a Hybrid MTS–MTO Production Model
No full textThe competition and the volatility of today’s production context require that enterprises are able to rapidly adapt to changes, reducing total costs in production. The main relationship between producer and consumer can be conducted through Make-To-Order (MTO) or Make-To-Stock (MTS) systems. This study proposes a hybrid MTS and MTO production system with a dynamic decoupling point. The proposed model concerns the monitoring of earliness and tardiness of customer orders to move the decoupling point towards MTS or MTO. Simulation models are proposed to test the proposed model following periodic or continuous review. The numerical results highlight that the best dynamic approach is the periodic review, which is more effective when the customer demand rate is higher
A Review of Game Theory Models to Support Production Planning, Scheduling, Cloud Manufacturing and Sustainable Production Systems
No full textCyber-physical systems, cloud computing, the Internet of Things, and big data play significant roles in shaping digital and automated landscape manufacturing. However, to fully realize the potential of these technologies and achieve tangible benefits, such as reduced manufacturing lead times, improved product quality, and enhanced organizational performance, new decision support models need development. Game theory offers a promising approach to address multi-objective problems and streamline decision-making processes, thereby reducing computational time. This paper aims to provide a comprehensive and up-to-date systematic review of the literature on the application of game theory models in various areas of digital manufacturing, including production and capacity planning, scheduling, sustainable production systems, and cloud manufacturing. This review identifies key research themes that have been explored and examines the main research gaps that exist within these domains. Furthermore, this paper outlines potential future research directions to inspire both researchers and practitioners to further explore and develop game theory models that can effectively support the digital transformation of manufacturing systems
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