scholarly journals Decision of Lead-Time Compression and Stable Operation of Supply Chain

Complexity ◽  
2017 ◽  
Vol 2017 ◽  
pp. 1-11 ◽  
Author(s):  
Songtao Zhang ◽  
Shuangshuang Li ◽  
Siqi Zhang ◽  
Min Zhang
Keyword(s):  
Supply Chain ◽  
Robust Control ◽  
Control Strategy ◽  
Lead Time ◽  
Cost Optimization ◽  
Inventory Level ◽  
Lead Times ◽  
Stable Operation ◽  
Optimization Strategy ◽  
Time Compression

A cost optimization strategy and a robust control strategy were studied to realize the low-cost robust operation of the supply chain with lead times. Firstly, for the multiple production lead times which existed in the supply chain, a corresponding inventory state model and a supply chain cost model were constructed based on the Takagi-Sugeno fuzzy control system. Then, by considering the actual inventory level, the lead-time compression cost, and the stock-out cost, a cost optimization strategy was proposed. Furthermore, a fuzzy robust control strategy was proposed to realize the flexible switching among the models. Finally, the simulation results show that the total cost of the supply chain could be reduced effectively by the cost optimization strategy, and the stable operation of the supply chain could be realized by the proposed fuzzy robust control strategy.

scholarly journals Discrete Switched Model and Fuzzy Robust Control of Dynamic Supply Chain Network

Complexity ◽  
2018 ◽  
Vol 2018 ◽  
pp. 1-11 ◽  
Author(s):  
Songtao Zhang ◽  
Chunyang Zhang ◽  
Siqi Zhang ◽  
Min Zhang
Keyword(s):  
Supply Chain ◽  
Fuzzy Control ◽  
Control Strategy ◽  
Low Cost ◽  
Lead Times ◽  
Stable Operation ◽  
Supply Chain Network ◽  
Customer Demand ◽  
The Common ◽  
Fuzzy Control Strategy

Supply chain network is more complex and dynamic under the uncertain demand and the lead time. Robustness is a key index of the stable operation for the supply chain network. We investigate a fuzzy robust strategy to realize the robust operation of the supply chain network with the production lead times and the ordering lead times under the uncertain customer demand. A discrete switched model of the dynamic supply chain network with the lead times and the uncertain customer demand is established based on T-S fuzzy systems. Then a fuzzy switched strategy is proposed to control the switching actions among subsystems. Furthermore, by introducing the inhibition rate γ, a fuzzy control strategy for the dynamic supply chain network is put forward to suppress the impacts of the lead times and the uncertain customer demand on the operation of the dynamic supply chain network. The fuzzy robust strategy composed of the fuzzy switched strategy and the fuzzy control strategy can guarantee the robust operation of the supply chain network at low cost. Finally, the simulation researches show the advantage of the proposed fuzzy robust strategy through the comparisons with the common robust strategy.

scholarly journals Fuzzy Control Model and Simulation for Nonlinear Supply Chain System with Lead Times

Complexity ◽  
2017 ◽  
Vol 2017 ◽  
pp. 1-11 ◽  
Author(s):  
Songtao Zhang ◽  
Yanting Hou ◽  
Siqi Zhang ◽  
Min Zhang
Keyword(s):  
Supply Chain ◽  
Fuzzy Control ◽  
Control Strategy ◽  
Control Model ◽  
Lead Times ◽  
Supply Chain System ◽  
Chain System ◽  
Model And Simulation ◽  
Definition Of ◽  
System Variables

A new fuzzy robust control strategy for the nonlinear supply chain system in the presence of lead times is proposed. Based on Takagi-Sugeno fuzzy control system, the fuzzy control model of the nonlinear supply chain system with lead times is constructed. Additionally, we design a fuzzy robust H∞ control strategy taking the definition of maximal overlapped-rules group into consideration to restrain the impacts such as those caused by lead times, switching actions among submodels, and customers’ stochastic demands. This control strategy can not only guarantee that the nonlinear supply chain system is robustly asymptotically stable but also realize soft switching among subsystems of the nonlinear supply chain to make the less fluctuation of the system variables by introducing the membership function of fuzzy system. The comparisons between the proposed fuzzy robust H∞ control strategy and the robust H∞ control strategy are finally illustrated through numerical simulations on a two-stage nonlinear supply chain with lead times.

scholarly journals Increasing Productivity by Reducing Manufacturing Lead Time through Value Stream Mapping

2012 ◽  
pp. 225-229
Author(s):  
Renu Yadav ◽  
Ashish Shastri ◽  
Mithlesh Rathore
Keyword(s):  
Lead Time ◽  
Value Added ◽  
Value Stream Mapping ◽  
Mapping Technique ◽  
Inventory Level ◽  
Lead Times ◽  
Business World ◽  
Value Stream ◽  
Current State ◽  
Future State

To survive in today’s competitive business world, companies require small lead times, low costs and high customer service levels. As such, companies pay more effort to reduce their manufacturing lead times. Value stream mapping (VSM) technique has been used on a broad scale in big companies such as Toyota and Boeing. This paper considers the implementation of value stream mapping technique in manufacturing helical springs by railway spring manufacturing company. It focuses on product family, current state map improvements and the future state map. The aim is to identify waste in the form of non value added activities & processes and then removing them to improve the performance of the company. Current state map is prepared to describe the existing position and various problem areas.. Future state map is prepared to show the proposed improvement action plans. The achievements of value stream implementation are reduction in lead time, cycle time and inventory level. It was found that even a small company can make significant improvements by adopting VSM technology. It was concluded that if we adopt the VSM technique the company could reduce the manufacturing lead time from 36.86 days to 34.06 days.

scholarly journals Robust Control of Supply Chain Networks with Multiple Lead Times and Demand Uncertainties

2019 ◽  
Vol 52 (13) ◽  
pp. 784-789
Author(s):  
Yongchang Wei ◽  
Song Zhu ◽  
Fangyu Chen
Keyword(s):  
Supply Chain ◽  
Robust Control ◽  
Lead Times ◽  
Supply Chain Networks

Comparative multi criteria analysis and dependent optimisation through integrated supply chain

2014 ◽  
Vol 63 (8) ◽  
pp. 1046-1069 ◽  
Author(s):  
Sanjay Sharma ◽  
Akshat Sisodia
Keyword(s):  
Supply Chain ◽  
Lead Time ◽  
Service Level ◽  
Inventory Level ◽  
Inventory Policies ◽  
Inventory Cost ◽  
Content Type ◽  
Customer Service Level ◽  
Integrated Supply Chain ◽  
Different Levels

Purpose – The purpose of this paper is to compare various inventory policies and their effect on various performance metrics at different levels of a multi stage supply chain. Later the model is integrated to include optimization of entire supply chain through implementation of collaborative supply chain model. Design/methodology/approach – Alternative inventory policies have been developed at different echelons and a comparison reflecting the usability on various factors such as inventory level, inventory cost and service level is presented so as to support the decision-making process. Various inventory policies such as economic order quantity, periodic ordering (T, M) and stock to demand have been considered. Along with the basic assumptions; lead time, demand variability, variability in demand during lead time, stock out costs have also been included to make the model more applicable to practical situations. Findings – After the selection of most appropriate inventory policy at each level through a decision matrix, the total cost of operating such a supply chain is calculated along with other parameters such as service level and inventory turns. The approach is of aggregating the optimized value at each echelon referred to as aggregated supply chain in the paper. Then the concept of integrated supply chain is introduced which optimizes the supply chain as a whole, rather than aggregating local optima. The comparison is made between the two approaches that prove the integrated supply chain's superiority. Furthermore, dependent optimization is run as it is not practically possible for each echelon to optimize at the same time. Originality/value – Each echelon is allowed to optimize at a time and other echelons assume corresponding values. This final comparative multi criterion analysis is based on the three factors, i.e. inventory cost, customer service level and inventory turnover with different weights assigned to each factor at different levels of a supply chain. Finally a consolidation of results is made to reflect the overall preference which proves that an integrated supply chain best serves all the parameters combined together.

Switchgear Component Commonality Design Method Considering Delivery Lead-Time and Inventory Level

2007 ◽  
Author(s):  
Haruki Kariya ◽  
Kazuhiro Izui ◽  
Shinji Nishiwaki ◽  
Masataka Yoshimura ◽  
Yoshiya Ogihara ◽  
...  
Keyword(s):  
Production System ◽  
Design Problem ◽  
Lead Time ◽  
Design Method ◽  
Inventory Level ◽  
Lead Times ◽  
Scale Production ◽  
Objective Functions ◽  
Inventory Cost ◽  
Production Problem

Product families are groups of related products that take advantage of part commonalities at various levels to streamline delivery of maximal product variety with minimal cost impact and as short as possible lead-times. This paper proposes a new integrated product design method for build-to-order production system based products, using the product family concept, which considers product performance, delivery lead-time and inventory cost. The development and discussion of this method uses a switchgear design problem as a concrete and practical design case. A build-to-order production system has been applied to switchgear manufacturing due to its small-scale production and a variety of customer requirements. However, if the risk of maintaining unsold inventory can be decreased, manufacturers can justify holding an amount of versatile inventory. In this paper, inventory production system is applied to the switchgear production problem to shorten the delivery lead-time. The switchgear design and production problem is formulated using three objective functions, which are subassembly procurement lead-time, inventory cost and area occupied by various switchgear configurations. Moreover, to assist inventory cost evaluations, a simulation procedure for the inventory system is proposed. The proposed method is used to obtain a Pareto optimal solution set of the three objective functions. Finally, an example switchgear design problem is solved to illustrate that optimal use of component commonalities across different modules can significantly reduce inventory costs, while also shortening product delivery lead-times.

Supply chain redesign for lead-time reduction through Kraljic purchasing portfolio and AHP integration

2019 ◽  
Vol 26 (4) ◽  
pp. 1194-1209 ◽  
Author(s):  
Augusto Bianchini ◽  
Andrea Benci ◽  
Marco Pellegrini ◽  
Jessica Rossi
Keyword(s):  
Supply Chain ◽  
Business Strategy ◽  
Lead Time ◽  
Small And Medium Enterprises ◽  
Evaluation Criteria ◽  
Portfolio Analysis ◽  
Lead Times ◽  
Content Type ◽  
Lead Time Reduction ◽  
Time Reduction

Purpose The purpose of this paper is to provide a flexible and extensible model for the classification of suppliers, within the purchasing guidelines and market trends of an Italian small company, leader in the production of street lamps. The model is applied to identify critical supply chains with the final objective of lead-time reduction. Design/methodology/approach The model is obtained by the application of the purchasing portfolio analysis through the construction of Kraljic matrix. Profit impact and supply risk criteria are selected according to the main company requirements, and then prioritized by the analytical hierarchy process (AHP). Finally, supply chain lead-times are analyzed with Gantt diagrams. Findings The application of the model allows the determination of company criticalities in terms of high lead-times and of the involved suppliers. The analysis of critical suppliers positioning in the Kraljic matrix allows the definition of some possible strategies to implement for lead-time reduction. Research limitations/implications Purchasing portfolio analysis and Kraljic matrix are practical instruments to quickly frame company purchasing situation, but their application is not simple due to the numerous and different factors involved, especially in small and medium enterprises (SMEs), where resource are scarce and several constraints limit operations. The objective of the research is the development of a practical tool for strategic purchasing, simple and robust to be implemented in SMEs, with limited resources and access to quantitative supplier data. Originality/value Evaluation criteria definition is one of the most difficult phases, such as their univocal and quantitative comparison. The problem of selecting and prioritizing both quantitative and qualitative criteria for suppliers classification is overcome with the combined application of Kraljic matrix and AHP. The newly integration of the two methodologies allows the realization of a reliable and robust model for suppliers classification, which can be easily adapted to company business strategy changes.

Order Penetration Point: Just a Stock within Production?

2013 ◽  
Vol 769 ◽  
pp. 367-373
Author(s):  
Johannes Nywlt ◽  
Michael Grigutsch
Keyword(s):  
Supply Chain ◽  
Lead Time ◽  
Raw Materials ◽  
Lead Times ◽  
Industrial Companies ◽  
Delivery Times ◽  
Work In Process ◽  
Schedule Reliability ◽  
Schedule Adherence ◽  
Downstream Processes

Nowadays, for customers the logistical performance of industrial companies is as important as the price and quality when buying decisions have to be made. It can be observed that considering the KPIs of logistical performance as quality figures, similar to the product quality, becomes quite popular within national and international markets. Two logistical performance key figures that can be pointed out in that context are short lead times and high schedule reliability. The delivery times demanded by markets often are shorter than the realizable lead times of products or the replenishment time of raw materials or purchased parts. In order to deliver the products in time, companies have the opportunity to implement so called order penetration point (OPP) within their productions. The OPP specifies the point within a production which connects upstream processes linked with work orders and downstream processes link with costumer orders. The OPP is often built up as a stock of unfinished goods. Currently companies position their OPP only with the goal to satisfy the demand of short lead times set by the market. Other logistical targets such as a low work-in-process (WIP), high schedule reliability or a high utilization are usually not taken into account. Hence, due to the complexity of positioning the OPP companies underestimate the logistical potentials that can be achieved by positioning the OPP optimally. In this publication the fundamental determining factors which both influence the position of the OPP and are influenced by the selected position of the OPP are presented. In particular the dependencies between the four logistical targets, lead time, WIP, schedule reliability and the grade of utilization, and the position of the OPP are discussed. Exemplarily the correlation between the position of OPP and the schedule adherence at the end of the supply chain are presented. It can be assumed that the schedule adherence increases by moving the OPP towards the end of the supply chain. Possible reasons that explain this particular effect, like the reduction of lead time variation, will be discussed in detail.

Distributed Control Strategy for Dynamic Supply Chain Network

2012 ◽  
Vol 562-564 ◽  
pp. 1728-1731
Author(s):  
Hai Dong ◽  
Shi Nan Yuan ◽  
Wei Ling Zhao
Keyword(s):  
Supply Chain ◽  
Distributed Control ◽  
Control Strategy ◽  
Dynamic Performance ◽  
Rate Of Change ◽  
Inventory Level ◽  
Supply Chain Network ◽  
Deterministic Demand ◽  
Control Framework ◽  
Product Inventory

A distributed control strategy based on model predictive control is applied to dynamic supply chain network. The optimisation-based controller aims at maximising customer satisfaction with the least operating costs. The model proves to be very useful in maintaining an inventory level that is just enough to satisfy customer demand. A move suppression term that penalises the rate of change in the transported quantities through the network increases the robustness of the control system. Dedicated feedback controllers are utilised to maintain product inventory at all nodes of the supply chain network within pre-specified target levels that are subsequently embedded within the optimisation-based control framework. Simulated results exhibit good dynamic performance under both stochastic and deterministic demand variations.

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