Showing papers on "Modeling and simulation published in 2006"

System Dynamics: Modeling and Simulation of Mechatronic Systems

Abstract: The standard in the field, updated and revised for today's complex mechatronic systemsMore than ever before, engineers are responsible for the total system design of the products they create. While traditional modeling and simulation methods are useful in the design of static components, they are of little assistance to those charged with designing mechatronic systems comprising a variety of technologies and energy domains. Engineers who design such complex systems need more sophisticated tools to help them think and visualize on a dynamic systems level. This book arms them with one of the most important of those tools-bond graph modeling, a powerful unified graphic modeling language.System Dynamics, Third Edition is the only comprehensive guide to modeling, designing, simulating, and analyzing dynamic systems comprising any number of electrical, mechanical, hydraulic, pneumatic, thermal, and magnetic subsystems. While it has been updated and expanded to include many new illustrations, expanded coverage of computer simulation models, and more detailed information on dynamic system analysis, it has lost none of the qualities that have helped make it the standard text/reference in the field worldwide. With the help of more than 400 illustrations, the authors demonstrate step by step how to:* Model a wide range of mechatronic systems using bond graphs* Experiment with subsystem models to verify or disprove modeling decisions* Extract system characteristics and predict system behaviors* Translate graphical models into complex mathematical simulations* Combine bond graph modeling with state-of-the-art software simulation toolsSystem Dynamics, Third Edition is an indispensable resource for practicing engineers as well as students of mechanical, electrical, aeronautical, and chemical engineering.

A systematic approach to exploring embedded system architectures at multiple abstraction levels

Abstract: The sheer complexity of today's embedded systems forces designers to start with modeling and simulating system components and their interactions in the very early design stages. It is therefore imperative to have good tools for exploring a wide range of design choices, especially during the early design stages, where the design space is at its largest. This paper presents an overview of the Sesame framework, which provides high-level modeling and simulation methods and tools for system-level performance evaluation and exploration of heterogeneous embedded systems. More specifically, we describe Sesame's modeling methodology and trajectory. It takes a designer systematically along the path from selecting candidate architectures, using analytical modeling and multiobjective optimization, to simulating these candidate architectures with our system-level simulation environment. This simulation environment subsequently allows for architectural exploration at different levels of abstraction while maintaining high-level and architecture-independent application specifications. We illustrate all these aspects using a case study in which we traverse Sesame's exploration trajectory for a motion-JPEG encoder application.

Development of a Unified Design, Test, and Research Platform for Wind Energy Systems Based on Hardware-in-the-Loop Real-Time Simulation

Abstract: Traditionally, offline modeling and simulation has been the tool of choice for improving wind energy system control strategies and their utility system integration. This paper exploits how a newly established real-time hardware-in-the-loop (HIL) test facility, which is designed for testing all-electric ship propulsion systems, can be utilized for wind energy research. The test site uses two 2.5-MW/220-rpm dynamometers and a 5-MW variable voltage and frequency converter to emulate a realistic dynamic environment, both mechanically and electrically. The facility is controlled by a digital real-time electric power system simulator that is capable of simulating electrical networks and control systems of substantial complexity, typically with a 50-mus time step. Substantial input/output allows the feedback of measured quantities into the simulation. A 15-kW mock-up motor-generator set is used to demonstrate some critical aspects of the concept including the implementation of a proposed neural-network-based sensorless maximum wind energy capture control. From the dynamic test results presented, it is concluded that the proposed system shows great potential for the development of a unified wind energy design, test, and research platform

A charge-modulated FET for detection of biomolecular processes: conception, modeling, and simulation

Abstract: A novel, solid-state sensor for charge detection in biomolecular processes is proposed. The device, called charge-modulated field-effect transistor, is compatible with a standard CMOS process, thus allowing fully electronic readout and large scale of integration of biosensors on a single chip. The detection mechanism is based on the field-effect modulation induced by electric charge changes related to the bioprocess. A model of the device was developed, to provide a manageable relationship between its output and geometric, design and process parameters. Extensive two- and three-dimensional simulations of the proposed structure validated the model and the working principle.

Modeling the fluid dynamics of electrowetting on dielectric (EWOD)

Abstract: This paper discusses the modeling and simulation of a parallel-plate Electrowetting On Dielectric (EWOD) device that moves fluid droplets through surface tension effects. We model the fluid dynamics by using Hele-Shaw type equations with a focus on including the relevant boundary phenomena. Specifically, we show that contact angle saturation and hysteresis are needed to predict the correct shape and time scale of droplet motion. We demonstrate this by comparing our simulation to experimental data for a splitting droplet. Without these boundary effects, the simulation shows the droplet splitting into three pieces instead of two and the motion is over 15 times faster than the experiment. We then show how including the saturation characteristics of the device, and a simple model of contact angle hysteresis, allows the simulation to better predict the splitting experiment. The match is not perfect and suffers mainly because contact line pinning is not included. This is followed by a comparison between our simulation, whose parameters are now frozen, and a new experiment involving bulk droplet motion. Our numerical implementation uses the level set method, is fast, and is being used to design algorithms for the precise control of microdroplet motion, mixing, and splitting

Inverter EMI modeling and simulation methodologies

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 electromagnetic compatibility cost by minimizing late redesign 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 three-dimensional (3-D) finite-element-analysis (FEA)-based parasitic parameter extraction tool-Ansoft Spicelink has been used substantially. To gain additional degree of confidence, the results obtained from FEA are verified with closed-form solutions and actual measurements.

Real-Time Finite-Element Simulation of Linear Viscoelastic Tissue Behavior Based on Experimental Data

Abstract: We propose an end-to-end solution to real-time and realistic finite-element modeling and simulation of viscoelastic soft tissue behavior. We provide an efficient numerical scheme for solving a linear viscoelastic FEM model derived from the generalized Maxwell solid, and present methods for measuring and integrating experimental data on the viscoelastic material properties of soft tissues into the model for realistic display of visual deformations and interaction forces. Our precomputation scheme and multilayer computational architecture enable the model's real-time execution with visual and haptic feedback to the user. Our approach includes time- and rate-dependent effects, which requires considering a node's loading history in our displacement computations at each cycle of the simulation

Contributions to the Modeling and Simulation of Mechanical Systems with Detailed Contact Analyses

Abstract: The motivation for this thesis was the need for further development of multibody dynamics simulation packages focused on detailed contact analysis. The thesis makes contributions in three different ...

SeSAm: implementation of agent-based simulation using visual programming

Abstract: In this paper, we present the most important features of SeSAm, a modeling and simulation platform for multi-agent simulations. Based on a declarative, explicit model representation and visual programming, it allows implementing models on specification level. Optimizing compilation allows efficient simulation of the explicit model representation. It was successfully applied in different areas, like biology, traffic or logistics simulation.

Unconstrained Paving and Plastering: Progress Update

Abstract: Modeling and simulation has become an essential step in the engineering design process. Modeling and simulation can be used during either the original design phases, or on assessment of existing designs. In either case, the end result is increased confidence in the design, faster time to market, and reduced engineering cost. An essential step in modeling and simulation is the creation of a finite element mesh which accurately models the geometric features of the model being analyzed. Meshes generated for three-dimensional models are typically composed of either all-tetrahedral or all-hexahedral elements. Some methods exist for the generation and analysis of hybrid meshes

Modeling of Microturbine Power Generation Systems

Abstract: This article presents the modeling and simulation of a microturbine generation system suitable for isolated as well as grid-connected operation. The system comprises of a permanent magnet synchronous generator driven by a microturbine. A brief description of the overall system is given, and mathematical models for the microturbine and permanent magnet synchronous generator are presented. Also, the use of power electronics in conditioning the power output of the generating system is demonstrated. Simulation studies have been carried out in MATLAB/Simulink under different load conditions.

Modeling, Simulation, and Optimization of Electrowetting

Abstract: Electrowetting is an elegant method to realize the motion, dispensing, splitting, and mixing of single droplets in a microfluidic system without the need for any mechanical—and fault-prone—components. By only applying an electric voltage, the interfacial energy of the fluid–solid interface is altered and the contact line of the droplet is changed. However, since the droplet shape is usually heavily distorted, it is difficult to estimate the droplet shape during the process. Further, it is often necessary to know if a process, e.g., droplet splitting on a given geometry, is possible at all, and what can be done to increase the system's reliability. It is thus important to use computer simulations to gain an understanding about the behavior of a droplet for a given electrode geometry and voltage curve. Special care must be exercised when considering surface-tension effects. We present computer simulations done with the Surface Evolver program and a template library combined with a graphical user interface (GUI) that facilitates standard tasks in the simulation of electrowetting arrays.

A Variational Approach to Modeling and Simulation of Grain Growth

Abstract: Most technologically useful materials arise as polycrystalline microstructures, composed of a myriad of small crystallites, called grains, separated by their interfaces, called grain boundaries. The orientations and arrangements of the grains and their network of boundaries are implicated in many properties across wide scales, for example, functional properties, like conductivity in microprocessors, and lifetime properties, like fracture toughness in structures. Simulation is becoming an important tool for understanding both materials properties and their processing requirements. Here we offer a consistent variational approach to the mesoscale simulation of these systems subject to the Mullins equation of curvature-driven growth in a two-dimensional setting. The main objective is to provide a calibration for future two-dimensional and three-dimensional efforts. We discuss several novel features of our approach, which we anticipate will render it a flexible, scalable, and robust tool to aid in microstructural prediction. Simulation results offer compelling evidence of the predictability and robustness of statistical properties of large systems, such as grain size distribution and texture, that are of immediate interest in materials science.

An Efficient TLM/T Modeling and Simulation Environment Based on Conservative Parallel Discrete Event Principles

Abstract: The paper presents an innovative simulation scheme to speed-up simulations of multi-clusters multi-processors SoCs at the TLM/T (Transaction Level Model with Time) abstraction level. The hardware components of the SoC architecture are written in standard SystemC. The goal is to describe the dynamic behavior of a given software application running on a given hardware architecture (including the dynamic contention in the interconnect and the cache effects), in order to provide the system designer with the same reliable timing information as a cycle accurate simulation, with a simulation speed similar to a TLM simulation. The key idea is to apply Parallel Discrete Event Simulation (PDES) techniques to a collection of communicating SystemC SC THREAD. Experimental results show a simulation speedup of a factor up to 50 versus a BCA simulation (Bus Cycle Accurate), for a timing error lower than 10−3.

Operation Control and Modeling-Simulation of AC-excited Variable-speed Constant-frequency(AEVSCF) Wind Power Generator

Abstract: The function principle of AC-exited VSCF wind power generation system is discussed and the control task and run characteristic of doubly-fed asynchronous wind generator before and after grid-connection are analyzed in this paper. Grid-connection control and maximal wind power tracing control of generator are investigated based on stator field-oriented vector control technique. By modeling generator respectively and time-sharing simulation, the AC-exited VSCF wind power generation simulation system is founded, which includes two modules named grid-connection module and wind power tracing module. These modules in which generator model and control strategy are different can simulate the whole progress before and after grid-connection based on time-sharing and data-transferring method. Fully simulation verified the correctness and validity of the modeling and control of AC-exited VSCF wind power generator discussed in this paper.

Efficient Representation and Simulation of Model-Based Designs.

Abstract: Actor-based design is based on composing a system of communicating processes called actors, which can only communicate with each other via channels. However, actor-based design does not constrain the communication behavior of its actors therefore making analyses of the system in general impossible. In a model-based design methodology the underlying Model of Computation (MoC) is known additionally which is given by a predefined type of communication behavior and a scheduling strategy for the actors. In this paper, we propose a library based on the design language SystemC called SysteMoC which provides a simulation environment for model-based designs. We will introduce the syntax and semantics supported by SysteMoC as well as discuss the simulation environment and present first results of using SysteMoC for modeling and simulation of signal processing applications. The library-based approach unites the advantage of executability with analyzability of many expressive MoCs. Finally, we compare the simulative performance of SysteMoC with other executable languages such as C++, regular SystemC, and modelling environments such as Ptolemy II.

Applying Cell-DEVS Methodology for Modeling the Environment

Abstract: Recent research efforts have focused on the analysis of environmental systems using cellular models. Although most of the existing solutions are based on the cellular automata formalism, this technique has some problems that constrain its power, usability and feasibility for studying large complex systems. Instead, combining cellular automata with discrete event systems specifications (DEVS) showed excellent results in terms of quality and performance. Despite these encouraging results, the environmental science/engineering community still prefers more traditional approaches, as DEVS-based techniques require a fundamental change of the modeling and simulation paradigm, while entailing expertise in advanced programming, distributed computing, etc. Cell-DEVS and the CD++ toolkit were created to address these problems: they simplify the construction of complex cellular models by allowing simple and intuitive model specification. The discrete event nature of the formalism provides better precision and performance, and models can run in different simulation environments (single user, real-time, distributed/parallel) without special expertise required. Environmental applications can be easily constructed, making it possible for users with basic training in the techniques and software tools to face the study of complex problems. We present the definition of different models of environmental applications, including the pollution on a basin, fire spreading, watershed formation and viability of a population, focusing on how to define such applications using Cell-DEVS methodology, using an approach that facilitates this paradigm shift.

New algorithms for macromolecular simulation

Abstract: Macromolecular Models: From Theories to Effective Algorithms.- Membrane Protein Simulations: Modelling a Complex Environment.- Modeling and Simulation Based Approaches for Investigating Allosteric Regulation in Enzymes.- Exploring the Connection Between Synthetic and Natural RNAs in Genomes: A Novel Computational Approach.- Learning to Align Sequences: A Maximum-Margin Approach.- Minimization of Complex Molecular Landscapes.- Overcoming Energetic and Time Scale Barriers Using the Potential Energy Surface.- The Protein Folding Problem.- Dynamical and Stochastic-Dynamical Foundations for Macromolecular Modelling.- Biomolecular Sampling: Algorithms, Test Molecules, and Metrics.- Approach to Thermal Equilibrium in Biomolecular Simulation.- The Targeted Shadowing Hybrid Monte Carlo (TSHMC) Method.- The Langevin Equation for Generalized Coordinates.- Metastability and Dominant Eigenvalues of Transfer Operators.- Computation of the Free Energy.- Free Energy Calculations in Biological Systems. How Useful Are They in Practice?.- Numerical Methods for Calculating the Potential of Mean Force.- Replica-Exchange-Based Free-Energy Methods.- Fast Electrostatics and Enhanced Solvation Models.- Implicit Solvent Electrostatics in Biomolecular Simulation.- New Distributed Multipole Metdhods for Accurate Electrostatics in Large-Scale Biomolecular Simulations.- Quantum-Chemical Models for Macromolecular Simulation.- Towards Fast and Reliable Quantum Chemical Modelling of Macromolecules.- Quantum Chemistry Simulations of Glycopeptide Antibiotics.- Panel Discussion.

Modeling and Simulation of the VideoRay Pro III Underwater Vehicle

Abstract: Accurate modeling and simulation of underwater vehicles is essential for autonomous control. In this paper, we present a dynamic model of the VideoRay Pro III microROV, in which the hydrodynamic derivatives are determined both theoretically and experimentally, based on the assumption that the motions in different directions are decoupled. The experiments show that this assumption is reasonable within operating conditions of the VideoRay Pro III. A computer simulation with 3D graphics is also developed to help user to visualize the vehicle's motion.

Particle-Based Stochastic Simulation in Systems Biology

Abstract: Computational modeling and simulation have become invaluable tools for the biological sciences. Both aid in the formulation of new hypothesis and supplement traditional experimental research. Many different types of models us- ing various mathematical formalisms can be created to represent any given biological system. Here we review a class of modeling techniques based on particle-based stochastic approaches. In these models, every reacting molecule is repre- sented individually. Reactions between molecules occur in a probabilistic manner. Modeling problems caused by spatial heterogeneity and combinatorial complexity, features common to biochemical and cellular systems, are best addressed us- ing Monte-Carlo single-particle methods. Several software tools implementing single-particle based modeling techniques are introduced and their various advantages and pitfalls discussed.

Modeling, simulation and optimization of gas networks with compressors

Abstract: We consider gas flow in pipeline networks governed by the isothermal Euler equations and introduce a new modeling of compressors in gas networks. Compressor units are modeled as pipe–to–pipe intersections with additional algebraic coupling conditions for the compressor behavior. We prove existence and uniqueness of solutions with respect to these conditions and use the results for numerical simulation and optimization of gas networks.

Intelligent agents, simulation, and gaming

Abstract: Artificial intelligence and intelligent agents are sources of synergy for simulation and computer-based games. They support striking realism of the physical environment and provide unique opportunities for learning and complex operations. This article's purpose is to explore the relationship of software agents to simulation and games. This includes agents with advanced cognitive abilities (introspection, perception, anticipation, and understanding) as well as those representing personality, emotion, and cultural aspects of individuals and societies including issues. A recent special issue of Simulation: Transactions of the Society for Modeling and Simulation International on agent-directed simulation (ADS) is introduced. As a prelude to its presentation, the promising synergy of artificial intelligence, simulation, and gaming is elaborated on. A unifying paradigm for the synergy of agents and simulation and gaming--namely, ADS--is presented. It includes agent simulation, agent-supported simulation, and agent-based simulation. Also, two different usages of the term agent-based simulation are clarified.

Numerically Efficient Finite Element Formulation for Modeling Active Composite Laminates

Abstract: Active systems have attracted a great deal of attention in the last few decades due to the potential benefits they offer over the conventional passive systems in various applications. Dealing with active systems requires the possibility of modeling and simulation of their behavior. The paper considers thin-walled active structures with laminate architecture featuring fiber reinforced composite as a passive material and utilizing piezoelectric patches as both sensor and actuator components. The objective is the development of numerically effective finite element tool for their modeling. A 9-node degenerate shell element is described in the paper and the main aspects of the application of the element are discussed through a set of numerical examples.

IED modelling for IEC61850 based substation automation system performance simulation

Abstract: This paper introduces the modeling of intelligent electronic device (IED) on OPNET modeler, a communication network modeling and simulation tool developed by OPNET TECHNOLOGIES. These configurable IED models allow to easily build substation automation system (SAS) network model with different topologies for all kinds of substations so that the dynamic performance issues could be studied during the planning stage and network performance problem could be caught ahead of the deployment stage. An example of using those models to construct SAS network on OPNET Modeller as well as the network performance simulation results is also included in this paper.