Modelling and simulation of fabrication and assembly plants: an object-driven approach

This paper presents the technical characteristics and methodologies underlying the computer-aided modelling and simulation of fabrication and assembly plants through an object-driven approach. The paper is organized in four main sections. The first and second sections discuss the needs for model integration and then outline the modelling and simulation approach used. The third and fourth sections illustrate an application of the approach for modelling and simulating a specific fabrication and assembly plant.     

The finite cell method for nearly incompressible finite strain plasticity problems with complex geometries

In this paper, the performance of the Finite Cell Method is studied for nearly incompressible finite strain plasticity problems. The Finite Cell Method is a combination of the fictitious domain approach with the high-order Finite Element Method. It provides easy mesh generation capabilities for highly complex geometries; moreover, this method offers high convergence rates, the possibility to overcome locking and robustness against high mesh distortions. The performance of this method is numerically investigated based on computations of benchmark and applied problems. The results are also verified with the $h$- and $p$-version Finite Element Method. It is demonstrated that the Finite Cell Method is an appropriate simulation tool for large plastic deformations of structures with complex geometries and microstructured materials, such as porous and cellular metals that are made up of ductile materials obeying nearly incompressible $J_2$ theory of plasticity.     

功能性纺织品开发仿真系统的分析与构建

为了分析和评估服装的热舒适性以及着装人体的物理、生理和心理特性并预测由服装、人体、环境三者形成的系统综合作用下的动态人体热湿舒适性感觉,本文提出一个针对该领域的仿真系统框架。该仿真框架包括一个交互性的预处理界面,一个用于描述人体、服装和环境相互作用的数学模型以及一套可视化的后处理工具。     

Mathematical modelling and finite element simulation of smart tubular composites

This paper presents a mathematical modelling and numerical simulation method for three-dimensional smart tubular 1(0)-3 composites based on a representative composite volume (RCV) approach. For the problems we consider, numerical results show that the maximum mechanical displacement varies linearly with the applied electrical potential and grows nonlinearly with increasing the RCV height. Further, we observe that decreasing the distance between the inner and outer radii results in increasing the maximum displacement. This refers to composites with large Young’s modulus of the polymer phase, whereas for “soft” polymers (i.e. for Young’s modulus of the polymers of order less than GPa) no particular ‘rule’ is evident, in which case the Poisson’s ratio is the most important parameter.     

Simulation of Railway Traffic Control

Traffic control is the centre of the railway traffic system. The success of a railway traffic simulation model depends very much on an adequate modelling of the traffic control. The main objective of a traffic control system is to minimise delays. Important tasks which contribute to this goal are controlling connections between trains, deciding about priorities and controlling the rotations of crew and rolling stock. In this paper, we discuss a simulation model of railway traffic which is centred around the traffic control functions. It is observed that an object-oriented approach to the modelling of traffic control presents itself as very natural. It results in a very flexible model, which can accomodate a range of present and future traffic control systems. Finally, we present some results of a simulation study that investigates the possibility of partially automating traffic control.     

Numerical modeling of heat exchange and unsaturated–saturated flow in porous media

We discuss the numerical modeling of heat and mass transport in unsaturated–saturated porous media. The heat is transported by infiltrated water underlying capillary and gravitation driven forces. Heat energy is governed by molecular diffusion, convection, dispersion and exchange between the infiltrated water and porous media matrix. An unsaturated–saturated flow is considered with boundary conditions reflecting the external driven forces. The presented mathematical model is motivated by analysis of hygrothermal isolation properties of facades. The main contribution is focused on the determination of model parameters including soil parameters, dispersion coefficients, thermal transmission coefficient, thermal conductivity of porous media matrix and external transmission coefficients. The used mathematical model does not include the vapor transport and its phase exchange with water due to vaporization and condensation. It will be the next step of our research. Thus, practical applications of our model are limited. The developed numerical method is a good candidate for solving corresponding inverse problems. Numerical experiments support our method.     

Agent-Based Social Simulation in Markets

We show that certain desired behavioural properties of agent-based models can be deterministically induced by an appropriate mathematical structure. We also point out problems related to the handling of parameters, and of the modelling of time, in agent-based models. Our purpose is to illustrate some problems of agent-based social simulations in markets, as a first step towards the more ambitious goal of providing a methodology for such simulations.     

Animation of deformable models

Although kinematic modelling methods are adequate for describing the shapes of static objects, they are insufficient when it comes to producing realistic animation. Physically based modelling remedies this problem by including forces, masses, strain energies and other physical quantities. The paper describes a system for the animation of deformable models. The system uses physically based modelling methods and approaches from elasticity theory for animating the models. Two different formulations, namely the primal formulation and the hybrid formulation, are implemented so that the user can select the one most suitable for an animation depending on the rigidity of the models. Collision of the models with impenetrable obstacles and constraining of the model points to fixed positions in space are implemented for use in the animations.     

TOWARDS A GLOBAL ANALYSIS OF SYSTEMS

In this paper a topological approach to the analysis or properties or systems is outlined and accounted for, which is called a Global Analysis of Systems (GAS). Let a topological space t of system; and a property P of systems from Σ be given. Define Σ _p = {σ∈Σ; σ has the properly P}. Then the main question of the Global Analysis of Systems is: how can Σ _p , be characterized in topological terms? We claim that three types of properties are worthy of being distinguished from this topological point of view. They are called structural, generic and residual properties, if I, appears to be an open, open and dense, and residual subset of I respectively. A motivation for the Global Analysis of Systems flowing from differential geometry, theory of dynamical systems, catastrophe theory and the theory of control systems is presented. In conclusion a significance of the Global Analysis of Systems, both far systems theory and for a better understanding of the fundamental relation Model—Reality, is discussed.     

Robot modelling — the tools needed for optimal design and utilization

There exists a recognized need to predict the actions of a robot or robot-type system. This paper investigates the requirements of the designers and users of such equipment and attempts to evaluate current work in this field. Much of the work being attempted is essentially novel and the aim is to minimize duplication and to concentrate effort in relevant areas.     

Reactive silica transport in fractured porous media: Analytical solution for a single fracture

A general analytical solution is derived by using the Laplace transformation to describe transient reactive silica transport in a conceptualized 2-D system involving a single fracture embedded in an impervious host rock matrix. This solution differs from previous analyses in that it takes into account both hydrodynamic dispersion and advection of silica transport along the fracture, and hence takes the form of an infinite integral. Several illustrative calculations are undertaken to confirm that neglecting the dispersion term may lead to erroneous silica distribution along the fracture and within the host matrix, and the error becomes severe with a smaller rate of fluid flow in the fracture. The longitudinal dispersion is negligible only at steady state or when the flow rate in the fracture is higher. The analytical solution can serve as a benchmark to validate numerical models that simulate reactive mass transport in fractured porous media.