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Showing papers on "Modeling and simulation published in 2003"


Journal ArticleDOI
TL;DR: Verification and validation of computational simulations are the primary methods for building and quantifying this confidence in modeling and simulation.
Abstract: Developers of computer codes, analysts who use the codes, and decision makers who rely on the results of the analyses face a critical question: How should confidence in modeling and simulation be critically assessed? Verification and validation (V&V) of computational simulations are the primary methods for building and quantifying this confidence. Briefly, verification is the assessment of the accuracy of the solution to a computational model. Validation is the assessment of the accuracy of a computational simulation by comparison with experimental data. In verification, the relationship of the simulation to the real world is not an issue. In validation, the relationship between computation and the real world, i.e., experimental data, is the issue.

735 citations


Book
30 Dec 2003
TL;DR: This is the first book to present complete simulation models built with MATLAB that can serve as virtual laboratories for predicting the impact of system design changes.
Abstract: The hands-on, example-rich guide to modeling and simulating advanced communications systemsSimulation is an important tool used by engineers to design and implement advanced communication systems that deliver optimal performance This book is a hands-on, example-rich guide to modeling and simulating advanced communications systems The authors take a systems-level approach, integrating digital communications, channel modeling, coding, elementary statistical estimation techniques, and other essential facets of modeling and simulation This is the first book to present complete simulation models built with MATLAB that can serve as virtual laboratories for predicting the impact of system design changes Coverage includes: Role of simulation in communication systems engineering Simulation approaches and methodologies Signal and system representations, filter models, noise generation, Monte Carlo simulation, and postprocessing Advanced techniques for modeling and simulating nonlinear and time-varying systems Waveform level and discrete channel models Performance estimation via Monte Carlo simulation Semianalytic simulation techniques Variance reduction techniques Co-channel interference in wireless communication systems, and more The authors also present detailed case studies covering phase-locked loops, CDMA systems, multichannel nonlinear systems, as well as a start-to-finish simulation of an advanced cellular radio systemPrentice Hall Series in Communications Engineering & Emerging Technologies, Theodore S Rappaport, Editor

418 citations


Journal ArticleDOI
TL;DR: Four algorithms for the identification of contact stiffness and damping during robot constrained motion are reviewed and the results indicate that the indirect adaptive controller has the best combination of performance and ease of use.
Abstract: In this paper, we review and compare four algorithms for the identification of contact stiffness and damping during robot constrained motion. The intended application is dynamics modeling and simulation of robotic assembly operations in space. Accurate simulation of these tasks requires contact dynamics models, which in turn use contact stiffness and damping to calculate contact forces. Hence, our primary interest in identifying contact parameters stems from their use as inputs to simulation software with contact dynamics capability. Estimates of environmental stiffness and damping are also valuable for force tracking and stability of impedance controllers. The algorithms considered in this work include: a signal processing method, an indirect adaptive controller with modifications to identify environment damping, a model reference adaptive controller and a recursive least-squares estimation technique. The last three methods have been proposed for real-time implementation in impedance and force-tracking c...

195 citations


Journal ArticleDOI
TL;DR: An advanced multimode-fiber-link model that was used to aid the development of Telecommunication Industry Association standard specifications for a next-generation 50-/spl mu/m-core laser-optimized multimode fiber is described.
Abstract: This paper describes an advanced multimode-fiber-link model that was used to aid the development of Telecommunication Industry Association standard specifications for a next-generation 50-/spl mu/m-core laser-optimized multimode fiber. The multimode-link model takes into account the interactions of the laser, the transmitter optical subassembly, and the fiber, as well as effects of connections and the receiver preamplifier. We present models for each of these components. Based on these models, we also develop an efficient and simple formalism for the calculation of the fiber transfer function and the signal at the link output in any link configuration. We demonstrate how the model may be used to develop specifications on transmitters and fibers that guarantee any desired level of performance.

162 citations


Journal ArticleDOI
TL;DR: In this paper, the authors developed a mathematical model for investigating the dynamic performance of a polymer electrolyte membrane fuel cell, which is based on physical laws having clear significance in replicating the fuel cell system and can easily be used to set up different operational strategies.

155 citations


Journal ArticleDOI
TL;DR: A new model for highway traffic networks based on a detailed description of the junctions, using multilane equations, is presented for network simulation and optimization.
Abstract: A new model for highway traffic networks based on a detailed description of the junctions is presented. To obtain suitable conditions at the junctions, multilane equations are introduced and investigated. The new model is compared with currently known models for traffic flow networks for several situations. Finally, the model is used for network simulation and optimization.

155 citations


Proceedings ArticleDOI
07 Dec 2003
TL;DR: In this paper, the authors propose a framework for integration of modeling, simulation, and visualization tools for emergency response, which will significantly improve the nation's capability in the emergency response area.
Abstract: A number of modeling and simulation tools have been developed and more are being developed for emergency response applications. The available simulation tools are meant mostly for standalone use. Addressing an emergency incident requires addressing multiple interdependent aspects of the situation. The simulation tools addressing different aspects of an emergency situation need to be integrated to provide the whole picture to planners, trainers, and responders. A framework is required to ensure that modeling and simulation tools can be systematically integrated together to address the overall response. This paper proposes a framework for integration of modeling, simulation, and visualization tools for emergency response. The development and implementation of the proposed framework will significantly improve the nation's capability in the emergency response area.

134 citations


Proceedings ArticleDOI
07 Dec 2003
TL;DR: This paper discusses a number of key issues regarding a simulation team, how to conduct a simulation study, the skills required and the steps involved, and provides project management guidelines and outlines pitfalls to avoid.
Abstract: Simulation is a powerful tool for the analysis of new system designs, retrofits to existing systems and proposed changes to operating rules. Conducting a valid simulation is both an art and a science. This paper provides an introduction to simulation and modeling and the main concepts underlying simulation. It discusses a number of key issues regarding a simulation team, how to conduct a simulation study, the skills required and the steps involved. It also provides project management guidelines and outlines pitfalls to avoid.

117 citations



Proceedings ArticleDOI
07 Dec 2003
TL;DR: The development and implementation of the proposed framework for integration of modeling, simulation and visualization tools for emergency response will significantly improve the nation's capability in the emergency response area.
Abstract: A number of modeling and simulation tools have been developed and more are being developed for emergency response applications. The available simulation tools are mostly meant for standalone use. Addressing an emergency incident requires addressing multiple interdependent aspects of the situation. The simulation tools addressing different aspects of an emergency situation need to be integrated to provide the whole picture to planners, trainers and responders. A framework is required to ensure that modeling and simulation tools can be systematically integrated together to address the overall response. This paper proposes a framework for integration of modeling, simulation and visualization tools for emergency response. The development and implementation of the proposed framework will significantly improve the nation's capability in the emergency response area.

79 citations


Proceedings ArticleDOI
10 Jun 2003
TL;DR: An analytical approach for estimating the queuing delay distribution on an Internet link carrying realistic TCP traffic, such as that produced by a large number of finite-size connections transferring files whose sizes are taken from a long-tail distribution is described.
Abstract: In this paper we describe an analytical approach for estimating the queuing delay distribution on an Internet link carrying realistic TCP traffic, such as that produced by a large number of finite-size connections transferring files whose sizes are taken from a long-tail distribution. The analytical predictions are validated against detailed simulation experiments and real network measurements. Despite its simplicity, our model proves to be accurate and robust under a variety of operating conditions, and offers novel insights into the impact on the network of long-tail flow length distributions. Our contribution is a performance evaluation methodology that could be usefully employed in network dimensioning and engineering.

Book ChapterDOI
01 Jan 2003
TL;DR: A perspective on modeling of complex systems leading up to the recent development of Modelica, which draws on object oriented methodology in computer science, differential algebraic equations in numerical mathematics and control theory.
Abstract: The role of modeling is becoming increasingly important in design and operation of complex natural and man-made systems. Models are also appearing as components of control systems because of the increased use of model based control strategies such as Kalman filters and model predictive control. Mechanized tools are necessary to fully exploit modeling. The development of modeling is therefore closely associated with the development of computational tools for simulation. There has been a very dynamic development from the beginning in the 1920s. At that time, the technology was available only at a handful of university groups who had access to mechanical differential analyzers. Today modeling and simulation are available at low cost on the desk of everyone who needs it. This paper presents a perspective on modeling of complex systems leading up to the recent development of Modelica, which draws on object oriented methodology in computer science, differential algebraic equations in numerical mathematics and control theory.

Proceedings ArticleDOI
02 Nov 2003
TL;DR: In this article, the authors describe two simulation approaches with time and frequency domain simulations and verifies them with experimental results, as long as the noise source and propagation path are properly modeled.
Abstract: A numerical prediction of electromagnetic interference (EMI) allows evaluation of EMI performances at the design stage and before prototyping. It can also help reduce the post-prototype EMC cost by minimizing late re-design and modifications of a drive implementation. This paper describes two simulation approaches with time and frequency domain simulations and verifies them with experimental results. Both time and frequency domain simulation approaches are found effective as long as the noise source and propagation path are properly modeled. The 3 dimensional finite element analysis (FEA) based parasitic parameter extraction tool - Ansoft Spicelink/spl trade//spl trade/ has been used substantially. To gain additional degree of confidence, the results obtained from FEA are verified with closed-form solutions and actual measurements.

Journal ArticleDOI
TL;DR: This paper reviews the research work on real-time physics-based modeling and simulation for AUVs and presents the rationale for the simulation architecture and the lessons learned.
Abstract: Autonomous underwater vehicles (AUVs) have many scientific, military, and commercial applications because of their potential capabilities and significant cost-performance improvements over traditional means for performing search and survey. The development of a reliable sampling platform requires a thorough system design and many costly at-sea trials during which systems specifications can be validated. Modeling and simulation provides a cost-effective measure to carry out preliminary component, system (hardware and software), and mission testing and verification, thereby reducing the number of potential failures in at-sea trials. An accurate simulation can help engineers to find hidden errors in the AUV embedded software and gain insights into the AUV operations and dynamics. This paper reviews our research work on real-time physics-based modeling and simulation for our AUVs. The modeling component includes vehicle dynamics, environment and sensor characteristics. The simulation component consists of stand-alone versus hardware-in-the-loop (HIL) implementation, for both single as well as multiple vehicles. In particular, implementation issues with regard to multitasking system resources will be addressed. The main contribution of this paper is to present the rationale for our simulation architecture and the lessons learned.

Book ChapterDOI
03 Apr 2003
TL;DR: A method for the hybrid modeling and simulation of genetic regulatory networks, based on a class of piecewiselinear (PL) differential equations that has been well-studied in mathematical biology, which makes qualitative predictions of the behavior of regulatory systems.
Abstract: The study of genetic regulatory networks has received a major impetus from the recent development of experimental techniques allowing the measurement of patterns of gene expression in a massively parallel way. This experimental progress calls for the development of appropriate computer tools for the modeling and simulation of gene regulation processes. We present a method for the hybrid modeling and simulation of genetic regulatory networks, based on a class of piecewiselinear (PL) differential equations that has been well-studied in mathematical biology. Distinguishing characteristics of the method are that it makes qualitative predictions of the behavior of regulatory systems and that it deals with discontinuities in the right-hand side of the differential equations. The simulation method has been implemented in Java in the computer tool Genetic Network Analyzer (GNA). The method and the tool have been used to analyze several networks of biological interest, including the network underlying the initiation of sporulation in Bacillus subtilis.

Book ChapterDOI
13 Jan 2003
TL;DR: The goal is to combine the strengths of functional programming and non-causal modeling to create a powerful, strongly typed fully declarative modeling language that provides modeling and simulation capabilities beyond the current state of the art.
Abstract: The modeling and simulation of physical systems is of key importance in many areas of science and engineering, and thus can benefit from high-quality software tools. In previous research we have demonstrated how functional programming can form the basis of an expressive language for causal hybrid modeling and simulation. There is a growing realization, however, that a move toward non-causal modeling is necessary for coping with the ever increasing size and complexity of modeling problems. Our goal is to combine the strengths of functional programming and non-causal modeling to create a powerful, strongly typed fully declarative modeling language that provides modeling and simulation capabilities beyond the current state of the art. Although our work is still in its very early stages, we believe that this paper clearly articulates the need for improved modeling languages and shows how functional programming techniques can play a pivotal role in meeting this need.

Book
01 Jan 2003
TL;DR: Using nanofiltration membranes for the recovery of phosphorous with a second type of technology for theovery of nitrogen is suggest to be a viable process.
Abstract: .................................................................................................................................IV ACKNOWLEDGMENTS ............................................ERROR! BOOKMARK NOT DEFINED. TABLE OF CONTENTS .......................................................................................................... VII LIST OF TABLES ........................................................................................................................ X List of Figures...............................................................................................................................XI

Proceedings ArticleDOI
09 Mar 2003
TL;DR: It is shown that Sesame significantly reduces model construction time through the use of modeling component libraries, hierarchy, and advanced model structure description features.
Abstract: The Sesame environment provides modeling and simulation methods and tools for the efficient design space exploration of heterogeneous embedded multimedia systems. In this paper we describe the Sesame software system and demonstrate its capabilities using several examples. We show that Sesame significantly reduces model construction time through the use of modeling component libraries, hierarchy, and advanced model structure description features.

Journal ArticleDOI
TL;DR: In this article, the authors presented a model in Simulink, which consists of a three-phase matrix converter, an induction motor, a field-oriented controller, and a power supply.
Abstract: This paper presents a model in Simulink, which consists of a three-phase matrix converter, an induction motor, a field-oriented controller, and a power supply. A simplified Venturini's modulation algorithm is used in the simulation model. This algorithm provides unity fundamental displacement factor at the input regardless of the load displacement factor and can be easily implemented in closed loop operation. Simulation results are presented for both input and output sides of the converter. These results demonstrate a high-performance matrix converter-fed induction motor drive with unity input displacement factor.

Journal ArticleDOI
TL;DR: This article presents the Heterogeneous Flow System Specification (HFSS), a formalism aimed to represent hierarchical and modular hybrid flow systems with dynamic structure and exploits the ability of the HFSS formalism to represent mutirate numerical integrators.
Abstract: This article presents the Heterogeneous Flow System Specification (HFSS), a formalism aimed to represent hierarchical and modular hybrid flow systems with dynamic structure. The concept of hybrid flow systems provides a generalization of the conventional concept of hybrid system and it can represent a whole plethora of systems, namely: discrete event systems, multicomponent and multirate numerical methods, multirate and multicomponent sampling systems, event locators and time-varying systems. The ability to join all these types of models makes HFSS an excellent framework for merging components built in different paradigms. We present several examples of model definition in the HFSS formalism and we also exploit the ability of the HFSS formalism to represent mutirate numerical integrators.

Proceedings ArticleDOI
01 Oct 2003
TL;DR: A optimization software tool, implementing an evolutionary algorithm from the literature, has been developed to achieve a set of best alternative mapping decisions under multiple criteria, some of which were further evaluated by the Sesame simulation framework.
Abstract: In the Sesame framework, we develop a modeling and simulation environment for the efficient design space exploration of heterogeneous embedded systems. Since Sesame recognizes separate application and architecture models within a single system simulation, it needs an explicit mapping step to relate these models for co-simulation. So far in Sesame, the mapping decision has been assumed to be made by an experienced designer, intuitively. However, this assumption is increasingly becoming inappropriate for the following reasons: already the realistic systems are far too complex for making intuitive decisions at an early design stage where the design space is very large. Likely, these systems will even get more complex in the near future. Besides, there exist multiple criteria to consider, like processing times, power consumption and cost of the architecture, which make the decision problem even harder.In this paper, the mapping decision problem is formulated as a multiobjective combinatorial optimization problem. For a solution approach, an optimization software tool, implementing an evolutionary algorithm from the literature, has been developed to achieve a set of best alternative mapping decisions under multiple criteria. In a case study, we have used our optimization tool to obtain a set of mapping decisions, some of which were further evaluated by the Sesame simulation framework.

Journal ArticleDOI
TL;DR: This paper presents a new methodology to simulate CDM behavior at chip level and a hierarchical approach associated with a CDM macromodel is developed to model a full-chip structure comprised of several functional subsystems and multiple power supplies.
Abstract: Electrostatic discharge (ESD) accounts for over 30% of chip failure which occurred during chip manufacturing. Inadvertent touching by human body or contact with assembler tray can lead to such ESD failures. The most dominant ESD model is the charged-device model (CDM) wherein energy-destructive failure is incorporated resulting from rapid inflow, or outflow, of high current. Conventional modeling and simulations of the CDM are engineered to describe the behavior of ESD protection circuits, hence have a limitation to account for chip-level charge transfer. This paper presents a new methodology to simulate CDM behavior at chip level. A hierarchical approach associated with a CDM macromodel is developed to model a full-chip structure comprised of several functional subsystems and multiple power supplies. Full-chip CDM simulation provides the analysis of chip-level discharge paths and failure mechanisms, especially focusing on the gate oxide reliability. The proposed method can easily be applied to the CDM failure analysis of any product ICs in the early design stage. As an example, simulation results of a mixed-signal application-specific integrated circuit processed in a 0.25-/spl mu/m CMOS technology show high correlation with the measurement data.

01 Jan 2003
TL;DR: This paper shows how a set of physical objects can be used as a modeling and simulation tool, merging hands-on tinkering with computer simulation, and hopes that System Blocks will enable children younger than sixth grade to model, simulate and analyze systems that are meaningful to them.
Abstract: We present System Blocks, a physical interface that makes it easier for children to model and explore dynamic systems. A set of computationally enhanced blocks, made of wood and electronics, System Blocks can assist K-6 educators to teach the complex concepts of system dynamics and causalities. Learning to understand dynamic systems is an essential step in understanding the world around us. However, learning it at university, high school or even middle school level might be too late. By this age children have already developed their own models of how the world works. In this paper we will show how a set of physical objects can be used as a modeling and simulation tool, merging hands-on tinkering with computer simulation. Using blocks that behave as stocks, flows, variables and constants, our hope is that System Blocks will enable children younger than sixth grade to model, simulate and analyze systems that are meaningful to them.


Proceedings ArticleDOI
01 Dec 2003
TL;DR: Three case studies are presented to highlight the importance of following well-established simulation techniques, of carefully describing experimental study scenarios, and of understanding assumptions sometimes unstated in the framework of a simulator.
Abstract: This paper calls attention to important practices in the modeling and the simulation of wireless ad hoc networks. We present three case studies to highlight the importance of following well-established simulation techniques, of carefully describing experimental study scenarios, and, finally, of understanding assumptions sometimes unstated in the framework of a simulator. The first case addresses the initial transient problem inherent to mobility and traffic generation sub-models. We quantitatively demonstrate how these transients can affect the simulation. Our second case illustrates the fact that strong scientific contributions can only be made via simulation studies when the models used are unambiguously specified. The example we use are simulations with and without a model for the ARP protocol. Finally, our third case discusses the importance of understanding the simulation tool and any default values used for model parameters. The example used relates to the use of the limited interference model.

Proceedings ArticleDOI
16 Mar 2003
TL;DR: The work shows that generating random numbers using the designed hardware can significantly increase the performance of simulation applications that require many random numbers.
Abstract: In modeling and simulation tools, random numbers from a variety of probability distribution functions are generated to simulate the behavior of random events. Inefficient generation of these numbers can be a significant bottleneck for simulation applications. Generating these random numbers imprecisely can skew results. An efficient and scalable fixed-point method for generating random numbers for any probability distribution function in a Field Programmable Gate Array (FPGA) is developed. A Pi estimator, a Monte Carlo integrator, and a stochastic simulator for chemical species are developed in software. Estimates are made regarding their potential to be accelerated using the designed FPGA. Results are presented which examine trade-offs between the number of gates used by the FPGA and the accuracy of the random numbers generated. The work shows that generating random numbers using the designed hardware can significantly increase the performance of simulation applications that require many random numbers.

Journal ArticleDOI
TL;DR: In this paper, the dynamic behavior of a hybrid actuator is studied by applying numerical simulation on the whole system, and Lagrangian mechanics is applied to derive equations of motion.

Journal ArticleDOI
TL;DR: The technological possibilities offered by the interoperability standard High Level Architecture (HLA) are introduced and discussed and the main focus is hereby on manufacturing applications, but the same approach is applicable to a wide range of other scenarios, e.g. in the area of supply chains, logistics, product simulation etc.
Abstract: In this article the technological possibilities offered by the interoperability standard High Level Architecture (HLA) are introduced and discussed. The main focus is hereby on manufacturing applications, but the same approach is applicable to a wide range of other scenarios, e.g. in the area of supply chains, logistics, product simulation etc. Especially for challenging objectives like the digital factory which many enterprises are currently facing, simulation applications are gaining growing importance. While simulations nowadays are often still applied for isolated problems, the consideration of the global context has a growing importance. A solution for solving this problem is offered by the distributed simulation paradigm: simulations are no longer single purpose applications. Rather, individual simulation models can be combined with each other for serving different purposes. Coupled simulations of different parts of a factory can be used to perform global optimizations. The same paradigm can be used for entire supply chains. For applying the distributed simulation paradigm, technological as well as organizational aspects have to be considered. On the technological side, it is necessary to integrate a certain interoperability standard into the tools which need to be coupled with each other. On the organizational level, an enterprise wide process has to be established, which defines how distributed modeling and simulation shall be applied. This article discusses solutions for both issues and illustrates them using a practical application scenario.

Proceedings ArticleDOI
02 Jun 2003
TL;DR: The design of state-of-the-art, complex embedded system requires the capability of modeling and simulating the complex networked environment in which such systems operate, and this implies the availability of both a networking modeling environment and traditional system-level modeling and simulation methodology.
Abstract: The design of state-of-the-art, complex embedded systems requires the capability of modeling and simulating the complex networked environment in which such systems operate. This implies the availability of both a networking modeling environment and traditional system-level modeling capabilities. In this paper we present a modeling and simulation methodology based on a timing accurate integration of a system-level modeling language (SystemC) and a network simulation environment (NS-2). The efficiency of the proposed design environment has been demonstrated on a description of a 802.11 MAC layer.

Book ChapterDOI
22 Sep 2003
TL;DR: The integrated environment SeSam and recent extensions are presented, that allow creating simulated environments for agent based software as well as actually developing and deploying software agents.
Abstract: In this paper we want to show the possibilities to use agent-based modeling and simulation for software development. Therefore we present the integrated environment SeSam and recent extensions, that allow creating simulated environments for agent based software as well as actually developing and deploying software agents.