Peter Lendermann

Distributed simulation with incorporated APS procedures for high-fidelity supply chain optimization

Tactical and operational planning for manufacturing enterprises are more important today than ever before as their supply chains span the globe. Two state-of-the-art technologies that are critical to success are discrete event simulation and advanced planning and scheduling. They are commonly applied in designing and executing operations at each site within the supply chain. However, as supply chains become leaner and more responsive, operational constraints and stochastic influences within the manufacturing sites and the logistics network require a combination of both technologies applied to the entire supply chain. This paper describes a novel framework for advanced distributed simulation with integrated APS procedures for collaborative supply chain optimization. The framework can be used for fast optimization of both planning procedures and execution policies and also provides a base for easy implementation of simulation results. A prototype of a distributed semiconductor supply chain simulation has been developed and is currently being refined.

Panel session: opportunities for simulation in supply chain management

It has become a matter of survival that many companies improve their supply chain efficiency. This presents an opportunity for simulation. However, there are many challenges that must be overcome for simulation to be a contributor to play an effective role. Four contributors discuss the opportunities that they see for simulation to play a meaningful role in the area of supply chain management.

Distributed Supply Chain Simulation as a Decision Support Tool for the Semiconductor Industry

The need for better understanding, control, and optimization of supply chains is being recognized more than ever in the new economy. Simulation holds a great potential in portraying the dynamic evolution of supply chains and providing appropriate decision support to address challenges arising from high variability and stochastic uncertainty. Realizing high-fidelity supply chain simulation will require integration of individual supply chain component simulation models and planning systems, shielding to prevent sensitive data from being shared indiscriminately, and even the geographical distribution of the supply chain component models. The authors discuss various conceptual and technical issues that have been successfully addressed to realize a prototype of distributed semiconductor supply chain simulation as well as implementation approaches that can be pursued. The prototype emulates a semiconductor supply chain consisting of two wafer fabs, an assembly and test facility, a distribution center, a warehouse, a supply chain planning module, a logistics provider, and customers.

A survey of challenges in modelling and decision-making for discrete event logistics systems

In this paper, we consider discrete event logistics systems (DELS). DELS are networks of resources through which material flow. They have been the subject of a large body of analytic research. A huge variety of specific models exists that generally require application by model and/or solution experts to answer narrowly-defined logistics questions about inventory, sourcing, scheduling, routing, etc. It has, however, proven difficult to integrate these models in any comprehensive way into information systems for logistics because of the lack of conceptual alignment between the models produced by researchers and the information systems deployed in practice with which they should be integrated. In this paper, we systematically identify several challenges for DELS research. We analyse the root of the difficulties for applying academic research results in DELS, and indicate some potential future research directions.

Analysis of a borderless fab using interoperating AutoSched AP models

Semiconductor front-end manufacturing is a complex process involving a large number of fabrication steps that require capital-intensive equipment. To address shortages that can arise in individual wafer fabs in situations such as machine breakdowns or unexpected surge in demand for some products, the concept of a borderless fab is presented in this paper. In a borderless fab, multiple wafer fabs pool their capacity together, allowing movement of partially completed wafer lots from one fab to another. This enables the redistribution of workload to other similar resources in alternative fabs to maintain the targeted production cycle time. For the purpose of this study, two wafer fabs within close proximity and with similar processing capabilities were modeled using the AutoSched AP (ASAP) simulation package. Instead of creating one single large model, each wafer fab is modeled as an individual ASAP model. Simulation is executed on two computers interconnected by a local area network. The High Level Architecture (HLA) standard is adopted to enable the distributed execution. A novel time synchronization algorithm is proposed that is approximately ten times more efficient compared to conventional algorithms. The interoperating ASAP models were then used to investigate the effect of different lot batching sizes on lot transfer frequency and the average production cycle time in a borderless fab scenario. The experimental results show how an optimal operating point for lot batching size can be obtained from the intersection point of normalized contradictory performance indices. The operating point yields a balance between the number of lot movements between fabs and average cycle time.

An integrated and adaptive decision-support framework for high-tech manufacturing and service networks

This article gives an update on a major international collaborative project under the integrated manufacturing and service systems initiative pursued by the Agency for Science, Technology and Research in Singapore. The objective of the project is to investigate how design, analysis, enhancement and implementation of critical business processes in a manufacturing and service network can be realized using one single simulation/application framework. The overall architecture of the framework outlines how commercial simulation packages and web service-based business process application components can be connected through a commercial application framework to achieve maximum leverage and re-usability of the application components involved. The project also addresses research issues with regard to mechanisms for interoperation between commercial simulation packages, symbiotic interaction between simulation-based decision support components and physical systems, and simulation speed-up through multi-objective optimal computing budget allocation techniques on a grid/cluster infrastructure.

Interoperating autosched AP using the high level architecture

The high Level Architecture (HLA) is an IEEE standard for interoperating simulation federates. In this paper, we describe a set of requirements that simulation packages need to satisfy in order to be made interoperable using the HLA standard. AutoSched AP, a commercial off-the-shelf simulation package (CSP) which is widely used in the semiconductor industry, was used as a case study for this interoperation exercise. We demonstrated that a straightforward customization of the CSP through a middleware that provides standard functions for interoperation may not provide a satisfactory solution. A specially optimized time synchronization mechanism needs to be installed to ensure good execution efficiency. Experimental results using a Borderless Fab model that comprises of two factory models show that an optimized time synchronization mechanism results in an execution time that is ten times better than a straightforward application of the HLA runtime infrastructures time synchronization mechanism.

About the need for distributed simulation technology for the resolution of real-world manufacturing and logistics problems

Distributed simulation has undergone several cycles of ups and downs in recent years. Although successful in the military domain, it appears that the idea of applying distributed simulation in other fields for modeling and analysis of large-scale, heterogeneous systems such as communication networks or supply chains has still not taken off until today. Is this because of inherent limitations or lack of applicability as such? Or is it because of additional research issues that are yet to be resolved to make distributed simulation applicable? In this paper, the problem is discussed specifically with regard to the application of distributed simulation for design, operation and performance enhancement of manufacturing and logistics systems

Application of multi-objective simulation-optimization techniques to inventory management problems

In this paper, we present how a solution framework developed for (a special case of) the multi-objective simulation-optimization problems can be applied to evaluate and optimally select the non-dominated set of inventory policies for two case study problems. Based on the concept of Pareto optimality, the solution framework mainly includes how to evaluate the quality of the selected Pareto set by two types of errors, and how to allocate the simulation replications according to some asymptotic allocation rules. Given a fixed set of inventory policies for both case study problems, the proposed solution method is applied to allocate the simulation replications. Results show that the solution framework is efficient and robust in terms of the total number of simulation replications needed to find the non-dominated Pareto set of inventory policies

Symbiotic simulation for business process re-engineering in high-tech manufacturing and service networks

In todays highly competitive business environment, the speed of a companys response to changes by adapting its own business processes is vital to its survival. In this paper, we propose a symbiotic simulation system that can monitor the real-world operations of high-tech manufacturing and service networks, carry out what-if analysis and optimization on service-oriented based business workflow, and dynamically deploy the optimized business workflow onto the real-world operations. A case study of an aerospace spare parts logistics system was carried out to investigate the viability of the system.