| In the development process of the manufacturing industry,the efficient assembly line has promoted the entire industrialization process.H owever,in today's multi-variety and small-batch market demand,the rigid drawbacks of the assembly line are increasingly evident.Seru production is an emerging production method based on assembly line.The production m ode combines the fl exibility of single production with the high efficiency of mass production,and is well adapted to the current market environment.A large number of companies have achieved considerable profits through the implementation Seru production.Therefore,the related theoretical research of Seru p roduction has become one of the most active research fields in today's operation management.Although many problem s such as the background,implementation conditions of Seru production and Line-Seru conversion have been clarified,the inherent mechanism of Seru production superior to the assembly line has not been systematically elaborated.Based on the implementation experience of Seru production and a large number of related research results,this study first confirms the effectiveness of Seru production relative to the assembly line.Subsequently,the inherent mechanism Seru production efficiency,flexibility and robustness,is studied in depth.First,the effectiveness of Seru production in a flexible production environment with multiple varieties and small batches is studied.According to the process design features of the two production systems,Seru production and assembly line,and the actual situation of random arrival batch products,the two production systems were com pared with products waiting service tim e as an index.The queuing theory and Markov chain theory are used to construct the average waiting queue length formulas of the two systems.The formula parameters corresponding to different scenarios are set and the average waiting queue length changed by Line-Seru conversion is analyzed.The results show that Seru production is more suitable for the flexible production environment of multi-variety and small-batch,which confirms the effectiveness of Seru production relative to the assembly line.Second,the flexibility of Seru production system is studied.The flexible production structure is determined according to the number of product types which each seru in the Seru production system is responsible for.Considering the efficien cy of flexible production structures,this paper focuses on a class of symmetric flexible structures called d-chains.Since the maximum expected sales represent the production quantity that meets the demand to the greatest extent and does not generate inventory,this paper uses the maximum expected sales of Seru production system realized by the d-chain to measure the flexible performance of this structure.The 2-chain structure is first studied and found that the maximum expected sales can be determined by solving the maximum flow problem.Since the 2-chain belongs to a closed chain,it is not easy to study the maximum flow.The 2-open chain with approximate structure is studied to get the maximum flow using the Markov chain theory.Finally,the maximum expected sales of the 2-chain system,that is,the metric expression of the 2-chain performance,is obtained.Next,the research idea of 2-chain flexibility is extended to the study of any d-chain flexibility.The difference is that the open chain corresponding to the d-chain structure has modular properties,and it is necessary to utilize the Markov chain theory for each part.Through numerical simulation,the following conclusions are drawn:(1)As the d-chain d value and system scale increase,the maximum expected sales of the Seru production system gradually increases.(2)The greater the degree of demand dispersion is,the more flexible the symmetry chain needs to be configured to improve system flexibility.Using the d-chain performance measurement method proposed in this paper,the flexible allocation decisions of Seru production system under general flexible production strategy and production strategy with partial stock are studied.In general flexible production strategy,based on operating leverage,a flexible configuration decision model with the goal of maximizing the expected profit is constructed to determine the optimal symmetrical flexible structure of the Seru production system.production strategy with partial stock is essentially a two-stage production process of the first stage of stock production and the second stage of flexible production.The performance of the Seru production system of the d-chain design is measured by the expected mismatch quantity of the stochastic demand and the two-stage capacity.The numerical simulation shows that although increasing the degree of flexibility(d value)can reduce the expected mismatch cost,it also increases the configuration cost.Comparing the increase and the decrease in cost,the ideal flexible production structure of the Seru production system under this strategy is determined.Third,the robust construction of Seru production system is studied.The construction of Seru production system is mainly composed of facility construction and cross-trained workers assignment.Since Seru production system with dispersed serus involves many areas,the probability unexpected facility failure and cross-trained workers shortage is high and the situation is complex.Therefore,this paper focuses on the robustness construction of this system from two aspects of serus location and cross-trained workers assignment.(1)The problem of reliable serus location considering backup supply strategy is studied.In response to the supply disruption caused by facility failure,a robust strategy of allocating backup supply serus to each customer is adopted.All serus may be interrupted at the same time in practice,so there is an expected loss cost that the customer's demand cannot be satisfied,and then a new customer allocation criterion is proposed.With the goal of minimizing the total cost of serus construction,expected transportation and expected losses,a reliable serus location allocation model is established,and the genetic algorithm is designed to solve the model.Taking the real supply network composed of a large chain enterprise in China as an example,the optimal serus location and multi-level customer allocation are determined to verify the validity of the model.Compared with the existing location allocation model,the proposed model considers the capacity constraint and reduces the total cost.It shows that the model is more in line with the actual situation and the optimized scheme has economic benefits.(2)The problem of reliable cross-trained workers assignment under the expected allocation strategy is investigated.The shortage of cross-trained workers is likely to lead to the loss of external services.In this paper,a robust strategy from the normal serus deployment to the damaged serus is used to help recover the operational capability.In view of this situation,considering the initial allocation of damaged serus and the number of shortages,the expected allocation criteria are formulated.The cross-trained workers optimization configuration model with the goal of operational efficiency and expected deployment cost is constructed,and NSGA-?is designed to solve the model.Take the assignment of cross-trained workers in six production bases of a large enterprise as an example,the validity of the model is verified.In the Pareto solution,the extreme pursuit of the expected deployment cost solution will lead to the idle of some cross-trained workers,and the lower bound of operational efficiency should be reasonably set according to the actual situation.Sensitivity analysis of the probability of cross-trained workers shortages shows that when the probability of shortage is small,the expected deployment cost will be less,and the shortage situation has less influence on the allocation decision.When the probability of shortage is increased by a small margin,the expected deployment cost is significantly increased.At this time,the shortage situation will significantly affect the allocation decision of the cross-trained workers.Seru production is a new form of production organization.The research results of this paper will improve the theoretical system of Seru production,and play a positive role in further conducting the research of Seru production and promoting the implementation of Seru production. |
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