Showing papers on "Modeling and simulation published in 1993"

Generating explanations of device behavior using compositional modeling and causal ordering

Abstract: Generating explanations of device behavior is a long-standmg goal of AI research in reasoning about physical systems. Much of the relevant work has concentrated on new methods for modeling and simulation, such as qualitative physics, or on sophisticated natural language generation, in which the device models are specially crafted for explanatory purposes. We show how two techniques from the modeling research--compositional modeling and causal ordering-- can be effectively combined to generate natural language explanations of device behavior from engineering models. The explanations offer three advances over the data displays produced by conventional simulation software: (1) causal interpretations of the data, (2) summaries at appropriate levels of abstraction (physical mechanisms and component operating modes), and (3) query-driven, natural language summaries. Furthermore, combining the compositional modeling and causal ordering techniques allows models that are more scalable and less brittle than models designed solely for explanation. However, these techniques produce models with detail that can be distracting in explanations and would be removed in hand-crafted models (e.g., intermediate variables). We present domain-independent filtering and aggregation techniques that overcome these problems.

Resource-Oriented Modeling and Simulation in Construction

Abstract: In modeling for simulation, the proper representation of crucial real-world variables is of prime importance. This paper describes the creation of a model that allows simulation of the construction process to be conducted in a simple fashion, in the field, and in a way that is oriented to the attributes of the specific resources available for the process. The developed model uses resources and their attributes as variables. This allows for consideration of resources of different sizes for the same work task, calculation of running task durations during simulation, rule-based release of resources from queues, and maintenance of detailed statistics on each type and size of resource used in the system. Experimentation with established equipment mixes and conditions as shown in published handbooks for earthwork processes has verified the capability of the system to predict production rates for differing equipment mixes and site conditions.

Modeling and simulation of hot-carrier-induced device degradation in MOS circuits

Abstract: The physical models and an integrated simulation tool are presented for estimating the hot-carrier-induced degradation of nMOS transistor characteristics and circuit performance. The proposed reliability simulation tool incorporates an accurate one-dimensional MOSFET model for representing the electrical behavior of locally damaged transistors. The hot-carrier-induced oxide damage can be specified by only a few parameters, avoiding extensive parameter extractions for the characterization of device damage. The physical degradation model includes both fundamental device degradation mechanisms, i.e., charge trapping and interface trap generation. A repetitive simulation scheme has been adopted to ensure accurate prediction of the circuit-level degradation process under dynamic operating conditions. >

On accurate modeling and efficient simulation of CMOS opens

Abstract: This paper presents a new modeling and simulation technique for CMOS opens. The significance of the method is that both the hazard and charge-sharing effects of all possible opens are modeled in terms of a set of detecting conditions. They are efficiently represented at logic level. Then during fault simulations only these detecting conditions are evaluated to decide if the opens are detected. In this way, all efficient simulation techniques developed at logic level can be applied. The paper shows how the detecting conditions are derived for arbitrary opens. Results of a parallel pattern simulator show a good trade-off of accuracy versus efficiency. >

SPICE Modeling and Simulation 1 of Hysteretic Current-Controlled C uk Converter

Abstract: Based on some new techniques which we have pro- posed for the modeling of PWM-controlled converters, the low- frequency behavior models of hysteretic current-mode controlled C uk converters, including the ones with coupled inductors, are developed. These models are simple, accurate and easy to use. Computer simulations based on such models are carried out for the analysis of the all/al: and al;/aI~ transfer characteristics and transient responses. The simulations are also verified by experimental measurements.

Mathematical modeling and simulation analysis of a pointing, acquisition, and tracking system for laser-based intersatellite communication

Abstract: A mathematical model of a pointing, acquisition, and tracking (PAT) system intended for laser-based intersatellite communication is developed and implemented in software in the form of a simulator. It represents major dynamic channels of the system and complex interaction of operational conditions, disturbances, and design parameters thus facilitating the solution of various analysis, design, and control problems. Application of computer graphics and animated schematics, driven by the model, provides accurate display of the most intricate phenomena behind the PAT operation. Coupled with a working laboratory prototype of the PAT system through a data communication board, the simulator is capable of displaying both simulated and real variables serving as a diagnostic tool. The simulator has been applied for development and verification of a novel jitter compensation scheme.

Representing and constructing system specifications using the system entity structure concepts

Abstract: A generative approach to constructing system specifications is discussed. This process is intended to support design of hierarchical, multicomponent systems. In previous work, a systems design methodology called Knowledge-Based Simulation Design (KBSD) was developed. KBSD focuses on the use of modeling and simulation techniques to build and evaluate models of the system being designed. To represent families of design components, a knowledge representation scheme called system entity structure (SES) is used. Various modeling formalisms may be used for system specifications in the methodology. Thus, an efficient, generative procedure is needed for constructing specifications for systems represented by an SES. It is shown how system specifications can be managed using a canonical SES representation.

An environment for DEVS-based multiformalism simulation in Common Lisp/CLOS

Abstract: The paper presents the realization of an object-oriented kernel of a new modeling and simulation environment. The kernel system stands out as it is based on systems theoretical concepts and facilitates combined discrete-continuous, modular, hierarchical modeling. Its implementation language is the AI language Common Lisp and its object-oriented superset CLOS. The kernel system serves as the basis for a knowledge-based modeling and simulation environment supporting interactive modeling and simulation and automatic model construction.

Automated modeling of physical systems in the presence of incomplete knowledge

Abstract: This dissertation presents an approach to automated reasoning about physical systems in the presence of incomplete knowledge which both supports formal analysis and proof of guarantees, and has been fully implemented and applied to substantial domain modeling problems. Predicting and reasoning about the behavior of physical systems is a difficult and important task that is essential to everyday commonsense reasoning and to complex engineering tasks such as design, monitoring, control, or diagnosis. A capability for automated modeling and simulation requires (1) expressiveness to represent incomplete knowledge, (2) algorithms to draw useful inferences about non-trivial systems, and (3) precise semantics to support meaningful guarantees of correctness. In order to clarify the structure of the knowledge required for reasoning about the behavior of physical systems, we distinguish between the model building task which builds a model to describe the system, and the simulation task which uses the model to generate a description of the possible behaviors of the system. This dissertation describes QPC, an implemented approach to reasoning about physical systems that builds on the expressiveness of Qualitative Process Theory (Forbus, 1986) and the mathematical rigor of the QSIM qualitative simulation algorithm (Kuipers, 1986). The semantics of QPC's modeling language are grounded in the mathematics of ordinary differential equations and their solutions. This formalization enables the statement and proof of QPC's correctness. If the domain theory is adequate and the initial description of the system is correct, then the actual behavior of the system must be in the set of possible behaviors QPC predicts. QPC has been successfully applied to problems in Botany and complex examples drawn from Chemical Engineering, as well as numerous smaller problems. Experience has shown that the modeling language is expressive enough to describe complex domains and that the inference mechanism is powerful enough to predict the behavior of substantial systems.

Modeling and simulation of advanced read channels

Abstract: As the density in digital magnetic recording is increased, various linear as well as nonlinear signal distortions affect the performance of detection algorithms. These include transition noise and electronics noise. The objective of this work is to evaluate the performances of several detection techniques at different linear densities, noise environments, and channel mismatch conditions using Monte Carlo simulation. The algorithms considered are the conventional peak detection, various maximum likelihood sequence detection methods and decision feedback type techniques. >

Computer modeling and simulation of camera defocus

Abstract: A computer model is presented for the formation and sensing of defocused images in a typical CCD camera system. A computer simulation system named IDS has been developed based on the computer model. IDS takes as input the camera parameters and the scene parameters. It produces as output a digital image of the scene as sensed by the camera. IDS consists of a number of distinct modules each implementing one step in the computer model. The modules are independent and can be easily modified to enhance the simulation system. IDS is being used by our group for research on methods and systems for determining depth from defocused images. IDS is also being used for research on image restoration. It can be easily extended and used as a research tool in other areas of machine vision. IDS is a machine independent and hence portable. It provides a friendly user interface which gives the user full access and control to the parameters and intermediate results.© (1993) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

The Manutec r3 benchmark models for the dynamic simulation of robots

Abstract: A detailed dynamic model of the industrial robot Siemens manutec r3 is described The parameters of the model have been acquired by measurements in our laboratory Simulation results of the model are presented as generated by the ANDECS (R) simulation environment The model serves as a demanding benchmark problem to test the modeling and simulation capabilities of robot simulation packages It is also used to investigate computer aided methods for control system design and dynamic trajectory planning

Hierarchical object nets—a methodology for graphical modeling of discrete event systems

Abstract: In this paper we introduce Hierarchical Object Nets as a modeling methodology for discrete event systems based on the DEVS (Discrete Event System Specification) formalism. We explain the modifications we propose and show how the methodology may serve as a basis for an open visual object-oriented modeling and simulation system. Further, the advanced concepts of active simulation objects and the prototype oriented model base are explained. The advantages of the concept for modeling, simulation and evaluation are reviewed.

Modeling and simulation of space robots

Abstract: A method based on the natural orthogonal complement is proposed for the development of dynamic models of space robots. As an illustration, the method is used to develop a computer simulation of a space manipulator that moves on a plane. The simulation results can be displayed using an animation program that has been developed in parallel to this research.

Modeling and Simulation of Coupling Structures for Quasi-Optical Systems

Abstract: Heron, Patrick Lascelles Modeling and Simulation of Coupling Structures for Quasi-Optical Systems. Under the direction of Michael B. Steer and James W. Mink Sponsored research was directed toward developing millimeter wave power sources utilizing quasi-optical techniques. A system consisting of an array of oscillators that radiated into a quasi-optical resonator was analyzed. Each oscillator was comprised of a solid state device and a radiating structure. A dyadic Green’s function was developed for a Fabry-Perot resonator which consisted of a metallic planar reflector and a shallow spherical metallic reflector. The Green’s function was applied to determine the driving point impedance matrix for an array of electrically small antennas within the resonator. An experimental X-band resonator was designed and fabricated, then one and two-port measurements were used to validate the theoretical calculations. A technique was determined for simulation of antennas that are not electrically small which radiate into the cavity. These techniques are shown to be applicable to coupling structures for quasi-optical systems in general. Practical considerations regarding the simulation of nonlinear solid state driving elements were addressed. A a technique for efficient Jacobian calculation using the multidimensional fast Fourier transform as well as a technique for simulator time-domain oversampling were developed so that multiple oscillator systems can be efficiently simulated. These simulation techniques were implemented and tested in a harmonic balance circuit simulator. I wish to dedicate this work to Karen. Without her patience, support, and sacrifice this work would not have been possible. I would like to thank Gregory Monahan for his assistance in design and construction of the experimental apparatus as well as for devising and applying the experimental measurement and de-embedding procedures. Gratitude is also due to Arthur Morris for his useful insights into electromagnetics and microwave systems. Finally, I wish to express my appreciation to the many largemouth bass who have waited patiently for this work to be completed. Biographical Summary Patrick L. Heron received the B.S.E.E. degree in 1983 from California State University Sacramento, the M.S.E.E. degree from University of Central Florida in 1987, and the Ph.D. in Electrical Engineering at North Carolina State University in 1993. From 1983 to 1987 he taught the Physics, Electrical Engineering, and Controls subjects at the United States Naval Nuclear Power School in Orlando, Florida. He is presently employed at Geophex Ltd. in Raleigh, NC. His research interests include, instrumentation and measurement, microwave and analog circuits, electromagnetics, and simulation of high speed circuits.

Analysis on steady state behavior of DEVS models

Abstract: B. P. Zeigler's (1984) DEVS formalism supports a unified modeling and simulation framework for discrete event systems, but it lacks an analytic means for reasoning about system behavior. To provide both analytic and simulation means for the formalism, an approach to analyzing the steady state behavior of DEVS models without simulation experiments is proposed. By establishing correspondence between a DEVS model and a continuous-time Markov chain in steady state, the approach transforms the given DEVS model into an equivalent continuous time Markov chain. By analyzing the Markov chain, various steady state probabilities, such as mean sojourn time and mean waiting time, are obtained. The proposed approach is validated by comparing the results from the approach with those from simulation experiments. >

Simulation of semiconductor devices and processes, vol. 5

Abstract: The SISDEP 93 conference proceedings present outstanding research and development results in the area of numerical process and device simulation. The miniaturization of today's semiconductor devices, the usage of new materials and advanced process steps in the development of new semiconductor technologies suggests the design of new computer programs. This trend towards more complex structures and increasingly sophisticated processes demands advanced simulators, such as fully three-dimensional tools for almost arbitrarily complicated geometries. With the increasing need for better models and improved understanding of physical effects, these proceedings support the simulation community and the process- and device engineers who need reliable numerical simulation tools for characterization, prediction, and development. This book covers the following topics: process simulation and equipment modeling, device modeling and simulation of complex structures, device simulation and parameter extraction for circuit models, integration of process, device and circuit simulation, practical applications of simulation, algorithms and software.

Cylinder Pressure Feedback Control Analysis Model

Abstract: This paper contains a brief description of a mathematical model suitable for systematic cylinder pressure based analysis and control design. A linearized form and a simplified discrete form of the model are presented to illustrate the synthesis of a control system that resulted in cylinder-by-cylinder dilution limit control with coordinated optimal spark timing control. The control law was initially embedded into a rigorous dynamic-thermodynamic engine model characterization followed by implementation on an engine system and trimming of the control law gains in an experimental environment. Comparative modeling and simulation results are presented.

The joint modeling and simulation system: a common modeling architecture for the DoD

Abstract: The Joint Modeling and Simulation System (J-MASS) is developing an architecture which will enhance the modeling and simulation (M&S) capability of the Department of Defense (DoD) community. The development standards and software tools implemented by J-MASS supports a disciplined approach to the development, configuration, operation, and analysis of digital models and simulations. J-MASS is an object-based modeling system designed to enhance supportability and maintainability. J-MASS will provide a library of verified and validated software components and models of weapon systems developed by the RDT&E community, models of threat systems developed by the intelligence community, and models of environmental effects provided by the scientific community. Because the models developed under J-MASS will have software components that are designed to consistent standards, the components can be reused to rapidly build other models and simulations. This ability to readily access and reuse existing models and components will result in large savings to the DoD in an era of shrinking budgets. J-MASS will truly provide the DoD with a common modeling architecture.

An object oriented methodology integrating design, analysis, modelling, and simulation of systems of systems

Abstract: Development of systems of systems outstrips the current software systems development strategy. A development strategy which integrates design, analysis, modeling and simulation using a methodology which integrates aspects of modular decomposition, object-oriented design, and distributed system design is reported. The methodology is illustrated in the design of a high bandwidth communications infrastructure for tactical armed forces. >

Overview of Modeling and Simulation

Abstract: This chapter contains sections titled: The Nature of Solar Processes, Numerical and Physical Experiments, Utility of Simulation, Simulation Programs, Design, Controls, Economic Analyses and Optimization, Meteorological Data Requirements, Validation, Problems and Accomplishments

Towards An Object-oriented Simulation Environment For Manufacturing Systems Analysis

Abstract: Industrial decision-makers need integrated simulation tools to assist them in the modeling, design-of-experiment and output analysis tasks. The object-oriented concept moves the focus towards the a more useful everyday-type of tool that would be organised around the model, the simulation module and a set of instruments. The whole would be tied into the manufacturing system to monitor its behavior according to important variables. This paper introduces COGNOSCO, a modular and evolutionary environment currently under development which follows these principles. It enhances model and component reusability and will encourage the use of the model on a real-time basis to assist in control and management. It will have the ability to learn both from the system and the user and to propose solutions to the problem of recovery from shocks. the creation of reusable blocks, which results in more user-friendly and modular software, which can be applied to a wider range of studies, providing better assistance to the user in completing these studies. This paper introduces an 00 manufacturing simulator developed within the framework of the ASMEMA project (Assistance MEcanique d la MAnutention), the aim of which is to create a tool for the multi-criteria evaluation of manned workspaces. This simulator is the first step towards the development of a "simulation environment" for the analysis of manufacturing systems in accordance with Norman's viewpoint. First, a brief overview of the uses of simulation in manufacturing and of simulation packages is presented to point out the strengths and weaknesses of simulation tools. Then, a similar overview of OQ modeling and simulation is followed by the description of the main modules of our environment. The last section briefly introduces the developments planned or completed thus far.