9836575
Optimal production-distribution planning in supply chain management using a hybrid simulation-analytic approach
Production-distribution planning is the most important activity in supply chain management (SCM). To solve this planning problem, either analytic or simulation approaches have been used. However these two approaches have their own demerits in problem solving. We propose a hybrid approach which is a specific problem solving procedure combining analytic and simulation methods to solve production-distribution problems in supply chains. The machine capacity and distribution capacity constraints in the analytic model are considered as stochastic factors and are adjusted by the proposed specific process according to the results from an independently developed simulation model which includes general production-distribution characteristics.
10452928
Detecting truncation point in steady-state simulation using chaos theory
In the steady-state simulation, it is important to identify initialization bias for the correct estimates of the simulation model under study. In this paper, the methods from chaos theory are applied to the determination of truncation points in the simulation data for controlling the initial bias. Two methods are proposed and evaluated based on their effectiveness for estimating the average waiting time in M/M/1(/spl infin/) queueing model.
14604625
Single run optimization using the reverse-simulation method
An efticient “Simulation Optimization” technique is developed to solve system design problems which can not be expressed in explicit analytical or mathematical models. In particular, we explore a new paradigm called the “Reverse-Simulation optimization method” which is quite Merent from current simulation optimization methods in the literature. This paper focuses on the method of on-line determination of steady-state, which is a very important issue in ReverseSimulation optimization, and the construction of a Reverse-Simulation algorithm with expert systems. The proposed algorithm finds the steady-state of a system and an optimal state. The algorithm employs the Lyapunov exponent of Chaos theory to determine both the steady-state and optimal state of a system.
46434197
Flow Control Strategy for Flexible Machining and Assembly System
Abstract In this paper an effective flow control strategy for a Flexible Machining and Assembly System is proposed using the concepts of operation-oriented and, combined push and pull control method. The proposed flow control mechanism could meet production demands with a minimum makespan while satisfying assigned due-dates and keeping a low volume of work-in-process at the same time. It also considers machine failures and rush jobs.
6327868
A schedulable garbage collection for embedded applications in CLI
Common language infrastructure (CLI) has been introduced as a core technology of Microsoft .NET. It enables "writing in multiple languages, running in multiple platforms" by providing virtual execution system (VES), common intermediate language, and common type system etc. The advantages of using CLI, including portability, compactness, and interoperability, could benefit the productivity of application software development and deployment. However, for embedded real-time systems, the applications' time-constraints cannot be satisfied easily due to several features of CLI runtime environment, such as thread priority, thread scheduling, garbage collection etc. In this paper, we aim to have a garbage collection mechanism applicable on real-time applications in CLI and other virtual machine environments. We achieve the goal by making the pause time of garbage collection operations predictable, and the invocation of garbage collection and applications schedulable. A cost model based on measured WCET is established to predict the execution time and overhead of garbage collection operations.
5961676
Total Data Quality Management: The Case of IRI
Abstract Implementing a Total Data Quality Management (TDQM) program is not a trivial undertaking. Two key steps are (1) to clearly define what an organization means by data quality and (2) to develop metrics that measure data quality dimensions and that are linked to the organization’s goals and objectives. This paper presents the case of Information Resources, Inc., which exemplifies how a company can develop a viable TDQM program.
5304492
Design specifications of a generic supply chain simulator
This paper describes a design specification for a generic, supply-chain-simulation system. The proposed simulation system is based on schedule-driven and stock-driven control methods to support the supply chain management. The simulation system includes three processing modes: business process flows, material process flows, and information process flows. The paper also discusses interface data requirements for the proposed supply-chain-simulation system.
6621245
Application of Machine Shop Data Model in Manufacturing Simulation
Simulation technology holds tremendous promise for the manufacturing industry. A machine shop data model has been developed at the National Institute of Standards and Technology (NIST) to represent neutral machine shop data for supporting machine shop manufacturing simulation [1]. This paper discusses the data model and its application in manufacturing simulation. The paper also proposes an application framework that integrates the simulation model, machine shop database, and machine shop XML (Extensible Markup Language) data document. A prototype system is developed to present the application of machine shop data model using the proposed framework.
749990
Optimal Checkpointing of Real-Time Tasks
Analytical models for the design and evaluation of checkpointing of real-time tasks are developed. First, the execution of a real-time task is modeled under a common assumption of perfect coverage of on-line detection mechanisms (which is termed a basic model). Then, the model is generalized (to an extended model) to include more realistic cases, i.e., imperfect coverages of on-line detection mechanisms and acceptance tests. Finally, we determine an optimal placement of checkpoints to minimize the mean task execution time while the probability of an unreliable result (or lack of confidence) is kept below a specified level. In the basic model, it is shown that equidistant intercheckpoint intervals are optimal, whereas this is not necessarily true in the extended model. An algorithm for calculating the optimal number of checkpoints and intercheckpoint intervals is presented with some numerical examples for the extended model.