Simulation Based Study of Safety Stocks under Short-Term Demand Volatility in Integrated Device Manufacturing.

© IEOM Society InternationalA problem faced by integrated device manufacturers (IDMs) relates to fluctuating demand and can be reflected in long-term demand, middle-term demand, and short-term demand fluctuations. This paper explores safety stock under short term demand fluctuations in integrated device manufacturing. The manufacturing flow of integrated circuits is conceptualized into front end and back end operations with a die bank in between. Using a model of the back-end operations of integrated circuit manufacturing, simulation experiments were conducted based on three scenarios namely a production environment of low demand volatility and high capacity reliability (Scenario A), an environment with lower capacity reliability than scenario A (Scenario B), and an environment of high demand volatility and low capacity reliability (Scenario C). Results show trade-off relation between inventory levels and delivery performance with varied degree of severity between the different scenarios studied. Generally, higher safety stock levels are required to achieve competitive delivery performance as uncertainty in demand increases and manufacturing capability reliability decreases. Back-end cycle time are also found to have detrimental impact on delivery performance as the cycle time increases. It is suggested that success of finished goods safety stock policy relies significantly on having appropriate capacity amongst others to support fluctuations

Supply chain collaboration

In the past, research in operations management focused on single-firm analysis. Its goal was to provide managers in practice with suitable tools to improve the performance of their firm by calculating optimal inventory quantities, among others. Nowadays, business decisions are dominated by the globalization of markets and increased competition among firms. Further, more and more products reach the customer through supply chains that are composed of independent firms. Following these trends, research in operations management has shifted its focus from single-firm analysis to multi-firm analysis, in particular to improving the efficiency and performance of supply chains under decentralized control. The main characteristics of such chains are that the firms in the chain are independent actors who try to optimize their individual objectives, and that the decisions taken by a firm do also affect the performance of the other parties in the supply chain. These interactions among firms’ decisions ask for alignment and coordination of actions. Therefore, game theory, the study of situations of cooperation or conflict among heterogenous actors, is very well suited to deal with these interactions. This has been recognized by researchers in the field, since there are an ever increasing number of papers that applies tools, methods and models from game theory to supply chain problems

Guide for certifying pressure vessels and systems

This guide is intended to provide methodology and describe the intent of the Pressure Vessel and System (PV/S) Certification program. It is not meant to be a mandated document, but is intended to transmit a basic understanding of the PV/S program, and include examples. After the reader has familiarized himself with this publication, he should have a basic understanding of how to go about developing a PV/S certification program

Serbia - public sector accounting review : report on the enhancement of public sector financial reporting

The government’s public financial management (PFM) Reform Program 2016-2020 foresees the gradual transition of public sector financial reporting from a cash basis to an accrual basis of accounting and the application of International Public Sector Accounting Standards (IPSAS). This will significantly improve the quality of financial information and should enable better informed decision-making, more efficient use of public funds and resources and improved fiscal performance. This Report on the Enhancement of Public Sector Financial Reporting is one output of the Serbia Public Sector Accounting Reform Technical Assistance project funded by the Swiss State Secretariat for Economic Affairs (SECO) through the Strengthening Accountability and Fiduciary Environment (SAFE) Trust Fund under the Public Sector Accounting and Reporting Program (PULSAR) which provides support for the development and implementation of public sector accounting standards. This report supports the development of a plan towards that goal by assessing the institutional framework for public sector accounting as well as the gap between Serbian public sector generally accepted accounting principles (PS GAAP) and IPSAS

The causes and determination of safety stocks in upstream supply chains for mass production of customized products

In an upstream supply chain dedicated to the mass production of customized products, many sources create production instability: the level and structure of production in the final assembly line, variability of lead times, quality issues, packaging and loading constraints on transportation, demand anticipation, and the synchronization of the flows of components sent, received, and produced. For periodic replenishment systems, each member of the supply chain must have two different safety stocks to prevent some sources of fluctuations: a safety stock of produced components to meet the demand of downstream links and a safety stock of supplied components to ensure its own production. Procedures must take the organizational framework of information and products exchanges into account. The relevance of supply and production rules depends on the relevance of structural information broadcast along the supply chain

Quantitative analysis of multi-periodic supply chain contracts with options via stochastic programming

We propose a stochastic programming approach for quantitative analysis of supply contracts, involving flexibility, between a buyer and a supplier, in a supply chain framework. Specifically, we consider the case of multi-periodic contracts in the face of correlated demands. To design such contracts, one has to estimate the savings or costs induced for both parties, as well as the optimal orders and commitments. We show how to model the stochastic process of the demand and the decision problem for both parties using the algebraic modeling language AMPL. The resulting linear programs are solved with a commercial linear programming solver; we compute the economic performance of these contracts, giving evidence that this methodology allows to gain insight into realistic problems.stochastic programming; supply contract; linear programming; modeling software; decision tree

Theory and Practice of Supply Chain Synchronization

In this dissertation, we develop strategies to synchronize component procurement in assemble-to-order (ATO) production and overhaul operations. We focus on the high-tech and mass customization industries which are not only considered to be very important to create or keep U.S. manufacturing jobs, but also suffer most from component inventory burden. In the second chapter, we address the deterministic joint replenishment inventory problem with batch size constraints (JRPB). We characterize system regeneration points, derive a closed-form expression of the average product inventory, and formulate the problem of finding the optimal joint reorder interval to minimize inventory and ordering costs per unit of time. Thereafter, we discuss exact solution approaches and the case of variable reorder intervals. Computational examples demonstrate the power of our methodology. In the third chapter, we incorporate stochastic demand to the JRPB. We propose a joint part replenishment policy that balances inventory and ordering costs while providing a desired service level. A case study and guided computational experiments show the magnitudes of savings that are possible using our methodology. In the fourth chapter, we show how lack of synchronization in assembly systems with long and highly variable component supply lead times can rapidly deteriorate system performance. We develop a full synchronization strategy through time buffering of component orders, which not only guarantees meeting planned production dates but also drastically reduces inventory holding costs. A case study has been carried out to prove the practical relevance, assess potential risks, and evaluate phased implementation policies. The fifth chapter explores the use of condition information from a large number of distributed working units in the field to improve the management of the inventory of spare parts required to maintain those units. Synchronization is again paramount here since spare part inventory needs to adapt to the condition of the engine fleet. All needed parts must be available to complete the overhaul of a unit. We develop a complex simulation environment to assess the performance of different inventory policies and the value of health monitoring. The sixth chapter concludes this dissertation and outlines future research plans as well as opportunities

Developing an analysis tool for risk calculation in supply chain operations

Problem: The case study company, BorgWarner, currently has no quantitative method for evaluating the risks connected to different inventory levels throughout their internal supply chain. Meanwhile there are internal goals for lowering the amount of capital tied in inventory. Purpose: The purpose of this thesis is to investigate how changes in the component and finished goods inventory levels affect the service level. Currently, the inventory level in each instance of inventory is set manually by the material and production planners and is based on their experience. Consequently, there is no way to evaluate the impact or quantify the risks of stock-outs if there is a decision to lower the inventory levels. The outcome of this thesis is a quantitative tool that shows how changes in inventory will affect the service level towards the customers and the capital tied in inventory. Delimitations: The scope is limited to only include BorgWarner TTS Landskrona and to only analyze the effect on the customers and products associated with the serial production. Only the immediate suppliers and customers will be included. Spare parts and any return flows are excluded from the scope of this thesis. Methodology: The thesis work was carried out by a comprehensive value stream mapping of all activities and processes connected to the internal supply chain, such as; forecasting, product assembly and stock keeping. The value stream map formed the basis for the data analysis from which statistical conclusions could be drawn. Finally, the analysis formed the basis for the quantitative tool. Result & conclusion: To fulfill the thesis’ purpose, a computerized analysis tool has been developed. The tool evaluates the effect a change in inventory level has on the service level and capital tied in inventory. The approach during this thesis has both contributed to the effectiveness of obtaining the results and for the validation of the analysis model