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.     

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.     

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。     

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).     

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.     

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。     

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.     

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.     

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.     

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.     

一种新的灰色预测模型及其建模机理

为了提高灰色模型的预测精度,并拓展其应用范围,针对具有近似非齐次指数律特征的数据序列,构建了一种新的灰色预测模型ＮＧＭ（１,１,k）．通过最小二乘法求出了新灰色模型参数的计算公式,以微分方程作为演绎推理工具,得到了该模型的时间响应序列函数,并对其建模精度进行了理论和实验分析．研究结果表明了所提出的灰色模型的有效性和适用性．     

Voltage source inverter driven multi-phase induction machine

Multi-phase (more than three phases) drives possess several advantages over conventional three-phase drives such as: reducing the amplitude and increasing the frequency of torque pulsations, reducing the rotor harmonic currents, reducing the current per phase without increasing the voltage per phase, lowering the dc link current harmonics and higher reliability. By increasing the number of phases it is also possible to increase the power/torque per rms ampere for the same volume machine. This paper, therefore, presents a simple d–q model of a multi-phase induction machine suitable for analyzing the transient, steady state and dynamic behavior of the machine under balanced operating condition. In the analytical model, the effects of common mutual leakage reactance between the two three-phase winding sets have been included. The model has been developed in general reference frame and is suitable for analysis of the machine behavior with an arbitrary angle of displacement.     

A modeling tool for simulating and design of on-chip network systems

The conception of Network-on-Chip (NoC) presents system designers with a new approach to the design of on-chip inter-connection structures. However, such networks present designers with a large number of design parameters and decisions, many of which are critical to the efficient operation of over-all on-chip system. To aid the design process of complex systems-on-chip, this paper presents a NoC simulation environment that has been developed and implemented using the SystemC transaction-level modeling language. The simulation environment consists of on-chip components as well as traffic generators, which can generate various types of traffic patterns. The simulation environment has also been integrated with the NoC topology generation tool being developed in our group. A set of simulation results demonstrates the types of parameters that can affect the performance of on-chip systems, including topology variations, network latency and achievable throughput. These results also verify the modeling capabilities of the proposed simulation environment.     

面向战略决策训练的群体行为仿真建模研究

针对当前面向战略决策训练的群体行为仿真中存在的:多注重表现,不注重系统本原数学模型的构建等问题进行了阐述,确立了该类型仿真的要点,给出了总体结构模型.并对意识形成模型、人际关系模型和视景表现等模型的构建进行了论述.可以说,为面向战略决策训练的群体行为的仿真建模研究提供了明晰的思路与方法.