A unified framework for modeling, simulating and explaining engineering systems

We present a unified framework which suffices to represent and manipulate physical objects and their relevant relations interactively in the context of modeling, simulating and explaining engineering systems, and which is demonstrated by an example of modeling river networks--environmental engineering systems[9].     

Animation of fracture by physical modeling

The breaking of solid objects, like glass or pottery, poses a complex problem for computer animation. We present our methods of using physical simulation to drive the animation of breaking objects. Breakage is obtaned in a three-dimensional flexible model as the limit of elastic behavior. This article describes three principal features of the model: a breakage model, a collision-detection/response scheme, and a geometric modeling method. We use networks of point masses connected by springs to represent physical objects that can bend and break. We present effecient collision-detection algorithms, appropriate for simulating the collisions between the various pieces that interact in breakage. The capability of modeling real objects is provided by a technique of building up composite structures from simple lattice models. We applied these methods to animate the breaking of a teapot and other dishware activities in the animationTipsy Turvy shown at Siggraph '89. Animation techniques that rely on physical simulation to control the motion of objects are discussed, and further topics for research are presented.     

A framework for formal modeling and analysis of organizations

A new, formal, role-based, framework for modeling and analyzing both real world and artificial organizations is introduced. It exploits static and dynamic properties of the organizational model and includes the (frequently ignored) environment. The transition is described from a generic framework of an organization to its deployed model and to the actual agent allocation. For verification and validation of the proposed model, a set of dedicated techniques is introduced. Moreover, where most computational models can handle only two or three layered organizational structures, our framework can handle any arbitrary number of organizational layers. Henceforth, real-world organizations can be modeled and analyzed, as illustrated by a case study, within the DEAL project line     

A template-based data specification framework for modeling physical security systems

Simulation studies often fail to provide any useful result due to its success being highly dependent on the skills of the analyst to understand a system and then correctly identify all the required data parameters and dependent variables. This paper describes a template-based framework to help identify and specify the components and data parameters for developing models of physical security systems. The layered framework consists of 15 templates built on top of 14 data primitives representing 119 data parameters. The modeling framework has been programmed as an internet-based web application and is simulation language-independent. The usefulness of the framework was tested and shown to have a significant impact on improving the identification of system components and their associated data parameters.     

一类改进故障树分析法的可靠性仿真及应用

从故障树分析法的基本概念和特点着手,提出了结合Faunet简化与线性时间（LinerTime）算法LTA的故障树结构简化两步策略,给出了故障树定性分析的算法描述及定量计算的数学推导,并将改进的故障树分析法用于某大型导弹的安全系统仿真。     

Intelligent simulation tools for mining large scientific data sets

This paper describes problems, challenges, and opportunities forintelligent simulation of physical systems. Prototype intelligent simulation tools have been constructed for interpreting massive data sets from physical fields and for designing engineering systems. We identify the characteristics of intelligent simulation and describe several concrete application examples. These applications, which include weather data interpretation, distributed control optimization, and spatio-temporal diffusion-reaction pattern analysis, demonstrate that intelligent simulation tools are indispensable for the rapid prototyping of application programs in many challenging scientific and engineering domains.     

A new modeling and control scheme for thyristor-controlled series capacitor

In order to design an optimal controller for the thyristor controlled series capacitor （TCSC）, a novel TCSC control model is developed. In the model, the delay angle of thyristor valves is the input, and the inductor current is chosen as the output. Theoretical analysis and simulation studies show that TCSC is a non-linear system and its parameters vary with the operating point. In consideration of the special characteristics of the TCSC, an improved model algorithmic control （1MAC） scheme is proposed to control TCSC effectively. The good performance can be observed from simulation results when IMAC is applied to a series compensated radial system.     

System-level modeling and simulation of biochemical assays in lab-on-a-chip devices

We present a “mixed-methodology” based system-level modeling and simulation for biochemical assays in lab-on-a-chip (LoC) devices. The methodology uses a combination of numerical schemes and analytical approaches to simulate biological and physicochemical processes, specifically, an integral approach for fluid flow and electric field, method of lines (MOL) and two-compartment models for biochemical reactions, and Fourier series-based model for analyte mixing. The solution procedure begins with decomposing the LoC device into a system of inter-connected components (e.g., channels and junctions) and the models are solved in a network fashion. Models are developed to accurately capture the multi-physics (e.g., flow, mixing, and reaction) behavior of individual components. The assembly of the components is facilitated via exchange of fluid flux and Fourier series coefficients (or average concentration) of analytes between various components, which enables network solution of the models. The system models are validated against both experimental and numerical models on various biochemical assays (e.g. immunoassays and enzymatic reactions), showing significant computational speedup (100–10,000-fold depending on the assay) without appreciably compromising accuracy (<10% error relative to numerical analysis).     

基于火电机组性能计算的软件建模与仿真

以电厂热力系统为目标对象,对其特点进行相关分析。以电厂基本设备为最小组成单位,将热力系统划分成若干模块,然后基于此为不同单元构建了相应的仿真模块。融合组态技术以及面向目标的设计理念,设计了能够对火电机组热力性能进行数据处理的计算软件,该软件主要包括以下模块：一、原始数据输入模块;二、仿真计算模块;三、结果输出模块;四、数据管理模块等。设置图形组态环境,同时构建热力设备所对应的仿真模型,能够让软件获得包括可视化和可组态化在内的两大基本功能,如此一来,赋予软件良好的通用性,使其可以满足多个机组、多种状态下的相关计算。     

Displacement constraints for interactive modeling and animation of articulated structures

This paper presents an integrated set of methods for the automatic construction and interactive animation of solid systems that satisfy specified geometric constraints. Displacement contraints enable the user to design articulated bodies with various degrees of freedom in rotation or in translation at highes and to restrict the scope of the movement at will. The graph of constrained objects may contain closed loops. The animation is achieved by decoupling the free motion of each solid component from the action of the constraints. We do this with iterative tunings in displacements. The method is currently implemented in a dynamically based animation system and takes the physical parameters into account while reestablishing the constraints. In particular, first-order momenta are preserved during this process. The approach would be easy to extend to modeling systems or animation modules without a physical model just by allowing the user to control more parameters.     

Multiphysics modeling and optimization of mechatronic multibody systems

Modeling mechatronic multibody systems requires the same type of methodology as for designing and prototyping mechatronic devices: a unified and integrated engineering approach. Various formulations are currently proposed to deal with multiphysics modeling, e.g., graph theories, equational approaches, co-simulation techniques. Recent works have pointed out their relative advantages and drawbacks, depending on the application to deal with: model size, model complexity, degree of coupling, frequency range, etc. This paper is the result of a close collaboration between three laboratories, and aims at showing that for “non-academic” mechatronic applications (i.e., issuing from real industrial issues), multibody dynamics formulations can be generalized to mechatronic systems, for the model generation as well as for the numerical analysis phases. Model portability being also an important aspect of the work, they must be easily interfaced with control design and optimization programs. A global “demonstrator”, based on an industrial case, is discussed: multiphysics modeling and mathematical optimization are carried out to illustrate the consistency and the efficiency of the proposed approaches.     

Combining analytical modeling,realistic simulation and real experimentation for the optimization of Monte-Carlo applications on the European Grid Infrastructure

Evaluating the performance of distributed systems through real experimentation is resource-consuming and by essence very difficult to reproduce. Conversely, analytical modeling and simulation facilitate investigation, but their level of realism needs to be evaluated to avoid misinterpretation. In this paper, we combine production experiments and realistic simulation for performance modeling and optimization of application workflows deployed on the European Grid Infrastructure (EGI), one of the largest distributed systems in the world. We use a validated simulator to (i) exhaustively evaluate an analytical model of the application makespan and (ii) study the influence and calibrate the parameters of the application workflow, in particular the checkpointing period. Experimental results show that the model fits the simulated makespan with a relative error of at most 15%, and that simulation allows us to validate analytical models in a more exhaustive manner than what is possible with production experiments. Results also show that, provided that the simulator is correctly validated and instantiated, simulation can be safely used for exhaustive parameter studies, allowing for a quick and fine tuning of sensitive application parameters.     

基于OPNET的局域网仿真建模与性能分析

基于以太网技术的小型局域网是我们日常生活和工作中常见的网络应用环境。如何快速适应网络拓扑环境的变化,构造出一个容量变化了的全新局域网是我们必须面,临的课题。通过OPNET网络仿真建模技术,我们可以对设计方案进行验证和预测,从而给出网络规划的可行性参考。文章围绕局域网的容量扩充这一典型案例,利用OPNET的仿真功能,通过对网络负载、数据传输时延和服务器响应时间等网络性能关键指标的分析,给出网络容量规划的依据。     

Simulation of service-oriented and distributed manufacturing systems

In this paper modeling and simulation is discussed in the context of distributed manufacturing systems (DiMS). The DiMS concept aims towards efficient and innovative collaboration that integrates design and development activities of manufacturing systems. A DiMS, described formally as a digital manufacturing system, is a competent basis for the modeling and simulation of manufacturing systems. The activities of the simulation model are described on the basis of a service-oriented approach in which content of the services is completely known. Micro, meso, and macro manufacturing levels are applied to the modeling and simulation. By means of these levels the hierarchy of the communication of the services is illustrated. An example is described in which modeling and simulation is used to proceed from ideas to efficiently operated manufacturing systems.     

Agent-oriented modeling of the dynamics of biological organisms

In this paper, the agent-oriented modeling perspective to cope with biological complexity is discussed. Three levels of dynamics can distinguished and related to each other: dynamics of externally observable agent behavior, dynamics of internal agent processes, and dynamics of multi-agent organisations. This paper addresses the first two. Basic agent concepts to describe externally observable agent behavior are introduced. In the context of two case studies on animal behavior and cell functioning, it is shown how these concepts can be used to specify dynamic properties. In addition, a number of basic agent concepts to describe an agent’s internal processes are introduced. Also, these concepts are illustrated for specification of dynamic properties in the two case studies. Furthermore, the relationships between dynamic properties of externally observable behavior and dynamic properties of internal agent processes are addressed and illustrated for the animal and cell case studies.     

Framework of grinding process modeling and simulation based on microscopic interaction analysis

This paper describes a framework of grinding process modeling to understand the grinding fundamentals and design grinding processes with predictive performance. The model regards grinding process as a time dependent process and an integration of microscopic interactions in the wheel-workpiece contact zone, including cutting, plowing, and sliding as well as other frictional interactions. The grinding process control and design are in fact to manage and balance all these interactions. The principles of microscopic interactions are analyzed and used to correlate the grinding process input parameters and performance output.     

Formal component-based modeling and synthesis for PLC systems

Programmable Logic Controllers (PLCs) are widely used in industry. PLC systems are reactive systems which run cyclically. In each cycle, the system state is checked and the program is executed once to determine the system behavior for a single cycle. Development of PLC systems conventionally follows the V-model, but increasing demand for efficiency and reliability requires a new rigorous and rapid design flow. In this paper, we propose a component-based formal modeling and synthesis method for cyclic execution platforms and apply it to PLC. Our method consists of three main phases: modeling, verification and code synthesis. In the modeling phase, the BIP (Behavior–Interaction–Priority) framework which is flexible and expressive is used as the modeling language. Real-time behavior, which is intensely concerned in PLC systems, can be modeled as well. In the verification phase, the system model is translated to timed automata and checked by Uppaal. Verification helps to ensure correctness of the model and further increases reliability of the implementation. In the code synthesis phase, the software part of the system model is extracted and synthesized to cyclic code. Although the PLC software runs cyclically, the software model is not necessarily given in a cyclic manner. We propose an algorithm which can generate high-performance cyclic code from a model which describes the business work-flow. This feature significantly simplifies program development. A set of tools is implemented to support our design flow and they are applied to an industrial case study for a PLC system that controls dozens of physical devices in a huge palace.