Decision Support for the Design of a New Production Plant Using Visual Interactive Simulation

Following promising results in test markets and successful pilot-scale manufacturing, the Board of a major Canadian manufacturer took the decision to proceed to develop the design for a full-scale production plant for a new advanced-technology product. The success of this new product was seen as critical to the Company's future, but Company personnel had limited experience with the new production technology and with the design of plants of this large scale. Finally, competitors from the USA and Europe were known to be working on similar products resulting in a sense of urgency in getting the product to the marketplace. A visual interactive decision support system built around a simulation model was developed using a methodology designed to help management understand the plant design issues and to help them resolve various key plant design options. When completed, the model gave management a tool which was used to analyse alternative plant designs and different production and manpower scheduling scenarios under a broad range of production conditions. The intensity of worldwide competition in this new product market, and the critical importance of this product to this Canadian corporation, have led to the decision to omit the name of the corporation from this article. In addition, certain production details have been disguised.     

Dynamics Modelling and Simulation Environment for Rapid Manipulator Design

For rapid development of space robotics mission scenarios, DLR provides an efficient assembly and simulation environment. It combines a CAD based robotic subsystems data base with kinematic and kinetic software tools for modeling and simulating the behaviour of the entire robotic system. In space environment, redundant manipulators are prefered. This paper addresses two implemented approaches for solving inverse kinematics and kinetics of such kind of systems.     

一种智能入侵检测系统设计与模拟实现

针对目前大多数的入侵检测系统存在的局限性,提出一种较完善的入侵检测模型,将专家系统和神经网络技术同时应用于入侵检测系统中.设计专家系统模块检测已知攻击,设计神经网络模块实现未知攻击的检测,提高了检测准确性.同时在神经网络模块应用PCA方法降低入侵数据维数,提高检测效率.仿真实验验证,该设计能有效降低入侵检测系统的漏报率和误报率.     

Decision-Making and the Simulation of Employment at Plant Level

This paper describes a manpower model devised to examine decision-making at plant level, and provides the results from its use in a paper mill in northern Scotland. Both supply and demand for manpower is simulated and possible rules used by management to evaluate and reconcile the situation are examined. Thus in the paper, the effect of "action-orientated" decision rules-minimal overstocking, fast line cutback/expansion, and swift moves towards voluntary redundancy if required-can be compared to "soft" decision rules under a variety of demand patterns.The results suggest that in number terms, the effect of management decision-taking is fairly small; however, in practice even the small divergence might be of considerable monetary value.     

A Computer Simulation Model Applied to Design Problems of a Petrochemical Complex

This paper describes a computer simulation model which was developed by BP Chemicals International and applied to some of the design problems of a petrochemical complex. The individual plants in this type of complex are closely interlinked in terms of input and output of raw materials, usage from common storage tanks and utilities requirements. Thus decisions taken within a particular area can have serious effects on overall site performance. The simulation model was constructed to assist management in evaluating the consequences of alternative design decisions.The structure and data requirements of the model are described and special mention is made of the decision rules used to arrive at a feasible mass balance. Limitations of the model are discussed and some sample applications are presented, including the problem of the sizing of storage tanks.     

Computer Simulation Models for a Multi-Specialty Ward

This paper describes computer simulation models of the utilization of shared resources by two E.N.T. consultants and two ophthalmology consultants in an English hospital. The resources in question are the hospital beds used by their patients, which are in the same wards, and the operating theatre, whose use they share.The validity of the models in relation to the actual system studied is assessed and experiments are described which evaluate alternative arrangements for the use of these resources.The models are discussed both as part of a continuing programme of research into hospital decision-making and as tools aiding the evaluation of the options open to hospital staff faced with a specific problem.     

A Metamodel Specification for a Tomato Processing Plant

This paper reports on the specification of a tomato processing plant cost-function using the Schruben-Cogliano (S-C) experimental procedure for response surface identification. The method is applied to a simulation model of a tomato processing plant in order to generate a cost-function metamodel that can be used to derive conditional factor-demand equations. The results suggest that the S-C methodology provides a means of deriving conditional factor-demand equations which reduces cost-function specification error.     

A Dynamic Simulation Comparing Classical and Emergent-Network Models: Organizational Design Implications

In the last decade, organizations have spent more on the creation, transformation, and communication of information than on the production of physical goods. The information age has been ushered in by the widespread assimilation of information and communication technologies. Many contemporary practitioners and organizational theorists predict the demise of the classical organizational design because of its inability to accommodate the sociological change engendered by the information age.The current study advances an emergent-network model of organizational design and compares it to the classical approach through a dynamic simulation of prototypical organizational activities. Organizational activities approximating one year were simulated in each of five organizations under constant baseline conditions and over one hundred experimental design conditions. The emergent network model manifested higher levels of goal attainment, resource utilization, and organizational capacity for accommodating change. These findings suggest that organizations will benefit from conformance to the design principals of the emergent-network model.Bernard D. Hill Jr. earned his Ph.D. in Public Policy and Administration from Virginia Commonwealth University. He also holds a Master of Science in Business and a Bachelor of Science in Education. Bernard is currently employed as a Chief Information Officer with the Commonwealth of Virginia. He has held a broad array of technology leadership positions in both the public and private sectors and the academic arena. Bernard was selected as one of Computerworld’s Premier 100 IT Leaders for 2002. As CIO for the Virginia Department of Transportation, he also brokered a public-private partnership that won a nationwide Government Technology Leadership Award. This partnership provides security awareness training for employees in Virginia State government, as well as cities, counties, and localities throughout Virginia.Heinz Roland Weistroffer is an Associate Professor of Information Systems in the School of Business at Virginia Commonwealth University. Roland holds a Doctor of Science degree from the Free University Berlin, Germany, and a Master of Arts degree from Duke University. Previous appointments include Chief Research Officer at the Council for Scientific and Industrial Research in Pretoria, South Africa, and Senior Lecturer at the University of Natal in Durban, South Africa. Roland’s current research interests include computer assisted decision support, computer simulation modeling, object oriented modeling, and software engineering. He has published in IEEE Transactions on Software Engineering, IEEE Transactions on Systems, Man and Cybernetics, the Journal of Multi-Criteria Decision Analysis, and Socio-Economic Planning Sciences, among other journals.Peter Aiken is Director of the Institute for Data Research and an Associate Professor of Information Systems at Virginia Commonwealth University. His research has widely explored the area of data engineering and its relationship to systems and business reengineering. He is the author of Data Reverse Engineering and Clive Finkelstein’s co-author of Corporate Information Portals (McGraw-Hill 1996/99). His sixth book is titled XML in Data Management and is co-authored with David Allen. He has held leadership positions with the US Department of Defense and consulted with more than 50 organizations in 14 different counties. His research publications have appeared in the Communications of the ACM, IBM Systems Journal, IEEE Software and many others. He is a member of ACM, and the IEEE (Senior Member). He has been a DAMA International Advisor since 1999 and received their 2001 International Achievement Award. He has lectured internationally on these and related topics.     

Simulation for business process re-engineering: case study of a database management system

This paper describes the use of discrete event simulation in the resource, throughput and content analysis and improvement of a business process in the Iranian Information and Documentation Centre (IRANDOC). The process was initially mapped using Data Flow Diagrams (DFD), and the objectives of the study for a range of users were captured using the Delphi method. The time taken for the tasks in the process were estimated by work study, and the simulation was developed in ServiceModel?. The simulation was valuable in understanding why the current systems were not performing satisfactorily and led to a number of proposals for improvement. This mixed use of hard (simulation) and soft (Delphi) methods proved a fruitful way to gain process improvements and could be employed in other organisations.     

Simulation for high Weissenberg number: Viscoelastic flow by a finite element method

In this work, we discuss a finite element/operator-splitting method for simulating viscoelastic flow at high Weissenberg numbers. This scheme is stable when simulating lid-driven cavity Stokes flow at high Weissenberg numbers.     

Simulation methods for queues: An overview

This paper gives an overview of those aspects of simulation methodology that are (to some extent) peculiar to the simulation of queueing systems. A generalized semi-Markov process framework for describing queueing systems is used through much of the paper. The main topics covered are: output analysis for simulation of transient and steady-state quantities, variance reduction methods that exploit queueing structure, and gradient estimation methods for performance parameters associated with queueing networks.The research of this author was supported by the U.S. Army Research Office under Contract DAAG29-84-K-0030.The research of this author was supported by the U.S. Army Research Office under Contract DAAG29-84-K-0030 and National Science Foundation Grant DCR-85-09668.     

电厂冷却水在湖泊和水库中热扩散过程的数学模拟

本文对电厂冷却水排入湖泊和水库后的热扩散过程进行了数学模拟,建立了三维扩散方程,给出了一维、二维和三维计算湖泊和水库中任意点任意时刻水温上升量的计算公式,并通过实例对一维情形的计算公式进行了验证,结果很好.     

Design and verify: a new scheme for generating cutting-planes

A cutting-plane procedure for integer programming (IP) problems usually involves invoking a black-box procedure (such as the Gomory–Chvátal procedure) to compute a cutting-plane. In this paper, we describe an alternative paradigm of using the same cutting-plane black-box. This involves two steps. In the first step, we design an inequality $cx \le d$ where $c$ and $d$ are integral, independent of the cutting-plane black-box. In the second step, we verify that the designed inequality is a valid inequality by verifying that the set $P \cap \{x\in \mathbb R ^n \mid cx \ge d + 1\} \cap \mathbb Z ^n$ is empty using cutting-planes from the black-box. Here $P$ is the feasible region of the linear-programming relaxation of the IP. We refer to the closure of all cutting-planes that can be verified to be valid using a specific cutting-plane black-box as the verification closure of the considered cutting-plane black-box. This paper undertakes a systematic study of properties of verification closures of various cutting-plane black-box procedures.     

Knowledge-Based Design and Simulation Environment (KBDSE): Foundational Concepts and Implementation

Research developments leading to implementation of an intelligent software environment supporting system design and simulation are presented. Knowledge-based system design and multifaceted simulation methodologies are a foundation for the system realization. The paper describes the major theoretical concepts and processes employed to develop and simulate design models. The environment implementing these concepts and methods consists of two basic components: one serves as a front end supporting the model construction processes; the other is an object-oriented, discrete-event simulator supporting evaluation of hierarchical, multi-component models. Current state of the system implementation and future work are discussed.     

纳米流体强化传热问题的高效算法设计及其高精度数值模拟

对周期性温度边界条件下方腔内Copper-水纳米流体的对流传热问题建立了完全四阶高精度紧致差分格式,并探讨了该格式高效算法设计,同时引入伪时间导数项采用Von Neumann方法证明了格式的绝对稳定性.研究了不同Ri数下纳米颗粒体积分数、左右边界温度的正弦振幅比和相位偏差对纳米流体传热效率的影响.数值结果表明,对于给定的Ri数,随着纳米颗粒体积分数的增大和边界温度的正弦振幅比的增加,纳米流体的传热效果会显著增强,而相位偏差只影响方腔右侧的温度分布.     

Simulation Study for the Clan of Ancestors in a Perfect Simulation Scheme of a Continuous One-Dimensional Loss Network

Perfect simulation of a one-dimensional loss network on ℝ with length distribution π and cable capacity C is performed using the clan of ancestors method. Previous works estimated the region of convergence of this scheme using a domination by a branching process. In this work, we show that the domination by the branching process is far from sharp and that there is room for improvement. Moreover, we derive an empirical relation concerning the critical value using simulation studies on the number of rectangles present in the clan of ancestors.      

Infinitesimal Perturbation Analysis: A Tool for Simulation

Perturbation analysis is a technique that expedites the process of performing experiments on discrete-event simulation models. This makes it possible to derive sensitivity estimates from one computer execution of a simulation model. Infinitesimal perturbation analysis (IPA) is one class of algorithms used in perturbation analysis. In this paper, the techniques and algorithms used in simulation to perform infinitesimal perturbation analysis are examined. Each algorithm is discussed in detail, with comments concerning implementation problems and examples with experimental results for serial transfer lines. The results of this paper show that for simple systems, IPA can be easily implemented in a general-purpose simulation language such as SIMAN. Unfortunately, for any given system, parameter or performance measure, the algorithm used to generate the gradient may vary. Additionally, algorithms for more complex classes of problems do not yet exist. This problem hampers the current possibility of incorporating IPA into general-purpose simulation languages.     

Perfect Simulation for a Stationary Silo with Absorbing Walls

The objective of this work is to generate random samples of the unique stationary distribution associated to the stochastic model for grain storage in a finite bidimensional silo. The support of this measure is an unbounded and continuous state space and therefore a truncation was necessary to apply the CFTP perfect simulation scheme. The performance of the algorithm was measured by comparing the sample moments to the theoretical ones.