Modelling and simulation of moving contact line problems with wetting effects

This paper presents a numerical scheme for computing moving contact line flows with wetting effects. The numerical scheme is based on Arbitrary Lagrangian Eulerian (ALE) finite elements on moving meshes. In the computations, the wetting effects are taken into account through a weak enforcement of the prescribed equilibrium contact angle into the model equations. The equilibrium contact angle is included in the variational form of the model by replacing the curvature with Laplace Beltrami operator and integration by parts. This weak implementation allows that the contact angle determined by the numerical scheme differs from the equilibrium value and develops a certain dynamics. The Laplace Beltrami operator technique with an interface/boundary resolved mesh is well-suited for describing the dynamic contact angle observed in experiments. We consider the spreading and the pendant liquid droplets to investigate this implementation of the contact angle. It is shown that the dynamic contact angle tends to the prescribed equilibrium contact angle when time goes to infinity. However, the dynamics of the contact angle is influenced by the slip at the moving contact line. This work has been partially supported by the German Research Foundation (DFG) through the grant To143/9.     

蠕虫扫描策略和流量模拟方法研究

对蠕虫扫描策略及其传播效率进行了深入分析;并提出了"带宽限制型 部分预定义目标地址列表 基于路由扫描 随机均匀扫描"的快速扫描策略.分析了各种蠕虫传播过程模拟方法和蠕虫流量模拟方法的优劣;并从统计意义上建立了"延迟限制型"蠕虫的周期性突发的扫描流量模型,结合混合层次模拟方法,能够为蠕虫模拟、检测和应对技术提供基础,同时减少了蠕虫模拟的复杂性.     

Modelling the software development process using an expert simulation system having fuzzy logic

This paper describes an intelligent computerized tool designed to aid managers of software development projects in planning, managing and controlling the development process of medium- to large-scale software projects. Systems dynamics is used to model and simulate the dynamic process of software development. The software development process is affected by some imprecise and vague variables that are treated as fuzzy variables. The simulation model is integrated with two expert systems. The fuzzy input variables to the system dynamics simulation model are handled by an input expert system having fuzzy logic. This expert system is designed to check the consistency of input variables. The simulation results are analysed by an output expert system having fuzzy logic. This expert system is designed to make recommendations based on experimentation with the simulation model.     

Modelling and simulation of a lighting control system

The objective of this paper was to regulate the amount of illumination in a room at a constant level, irrespective of the disturbances from outside such as weather conditions or the use of blinds to avoid the glare risk. In order to produce a model of the lighting system in our project, the supply voltage to the lamp dimmer circuits was varied stepwise and the resulting response – measured by the light sensors – was captured with a data-acquisition board. A nonlinear static characteristic in series with a linear 3rd order dynamic system was obtained from this experiment. The model was then used to implement and to validate a lighting system simulator, which was then further used to design, tune, test and evaluate efficient lighting controllers. The control design was rather challenging because the system is highly nonlinear and because undesired interaction occurs between multiple illumination zones in a big office room. The main benefits are a higher level of comfort and a continuous saving of energy.     

Modelling and simulation of a copper electrolysis cell group

The energy consumption of the copper electrolysis process is relatively high. Electrical disturbances – like contact failures and short circuits – even increase the energy consumption and also reduce the quality of copper produced. To better understand and improve the process, a computationally feasible and reliable model of copper electrolysis cell group is of great importance. In this paper a multiphysical FEM model of copper electrolysis cell group is presented. A number of simplifications are proposed to make the model computationally feasible.     

面向对象的蠕虫仿真方法研究

本文首先分析了网络蠕虫的特征行为,从宏观和微观两个层次对蠕虫进行了研究,并指出借助仿真实验来研究蠕虫的方法的优势所在;然后通过对仿真环境的构造的分析和对仿真动力来源的介绍,详细阐述了蠕虫仿真的基本过程;最后给出面向对象的网络蠕虫仿真的基本思路与方法。     

Modelling, simulation and control in a data-rich environment

This paper describes the use and potential use of mathematical modelling, computer simulation, real-time parameter identification and adaptive feedback control techniques in data-rich clinical environments. We consider a system to be operating in a data-rich environment when measurements of system inputs and outputs are frequently available. Two particular application examples which illustrate the power of these techniques will be examined. The first example that will be described involves the development and testing of a real-time adaptive controller for simultaneous regulation of mean arterial pressure and cardiac output using two drugs. The second application of these techniques involves the real-time control of electrical stimulation for the functional use of paralyzed muscles in neuroprosthetic devices.     

Computer aided analysis on the meshing behavior of a height-modified dual-torus double-enveloping toroidal worm drive

A flank modification methodology is proposed for the double-enveloping toroidal worm drive and a novel type of the dual-torus double-enveloping toroidal worm drive (the DTT worm drive) is developed. Because the height variation of the tool relative to the position during generating an unmodified worm is the unique modification parameter, this novel type of worm drive can be named as the height-modified DTT worm drive. Based on a strict meshing analysis, the selection principle of the modification style is recommended. A systematic and thorough study is conducted on the meshing behavior of the height-modified DTT worm pair by means of a computer simulation. The investigation results show that the height-modified DTT worm drive has favorable meshing performance.     

Vibration analysis of a contact slider/gimbal of a flexible disk drive

 To design contact-type gimbal system for a newly developed removable flexible disk drive called Card size flexible disk drive (CFDD) (Shinpuku et al., 2001; Ryoson et al., 2001), the gimbal's vibration characteristics in the disk-rotation direction were measured and simulated using FEM. To determine the relationship between vibration and friction in the head disk interface (HDI), a hard disk was also used. The friction characteristics were inserted into the FEM model based on the results. The gimbal was modified to suppress vibration amplitude to half in both simulation and experiment. Received: 5 July 2001/Accepted: 1 November 2001 Paper presented at the 12th Annual Symposium on Information Storage and Processing Systems, Santa Clara, CA, USA, 28–29 June, 2001.     

Modelling and simulation of porous immersed boundaries

The immersed boundary method has been used to simulate a wide range of fluid–structure interaction problems from biology and engineering, wherein flexible solid structures deform in response to a surrounding incompressible fluid flow. We generalize the IB method to handle porous membranes by incorporating an additional transmembrane flux that obeys Darcy’s law. An approximate analytical solution is derived that clearly illustrates the effect of porosity on the immersed boundary motion. Numerical simulations in two dimensions are used to validate the analytical results and to illustrate the motion of more general porous membrane dynamics.     

Modelling and simulation of an underwater manipulator

Recently, applications of articulated manipulators have increased to include extreme environments such as underwater and space. Simulation systems to support the design and control of industrial robots have been developed in many laboratories, and some high-speed calculation methods for inverse dynamics analysis of manipulators with series connections have been proposed. This paper deals with the dynamic simulation and modelling of underwater articulated manipulators. The dynamics of the above manipulators are formulated to evaluate the influence of the added mass tensor, the added inertia tensor, and fluid drag, and the lift on each arm according to classical Newton-Euler mechanics. Moreover, by generalizing this model, we can discuss the dynamics of a manipulator with dual arms and simulate some constrained motion of an end-effector. As an example of inverse dynamics analysis, the force and moment of a nine degrees of freedom (d.o.f.) manipulator with dual arms are analysed. As an example of direct dynamics analysis, hybrid control of both the force and the position of a 6 d.o.f. manipulator is simulated.     

Modelling and / for / by simulation

Various aspects of the close interconnection of the two tasks ‘Modelling a System’ and ‘Simulating a System’, shall be discussed for continuous systems. Some typical examples from different areas of application will be given in order to provide some insight into this matter. Then the importance of implicit programming will be discussed shortly which allows for a ‘one-to-one-mapping’ of the system block structure on the simulation program. Some remarks on available simulation tools will complete the discussions.     

面向方框图仿真的模型建立与仿真计算

在对高阶系统及非线性系统进行仿真时,需要求解高阶微分方程与非线性微分方程。当中的变量耦合问题较难处理,面向方框图仿真方法可以较好地解决这个问题,仿真计算简单,界面直观,对控制系统的设计起较好的辅助作用。主要介绍面向方框图的仿真模型的建立方法,讨论线性及非线性微分方程的方框图模型,并简单介绍面向方框图的仿真计算和误差分析。     

Modelling and numerical simulation of an epitaxial reactor

The purpose of this article concerns the modelling of the thermal behaviour of an epitaxial reactor. Numerical simulations (FORTRAN and CSMP III) are very useful for testing the validity of simplified models obtained from a complex non linear distributed parameter system.     

The research of load spectrum between flexible gear and wave generator of harmonic drive

The harmonic drive is a kind of gear transmission that uses wave generator to produce controllable soft round elastic deformation and engages with rigid gear to transmit motion and power.The load distribution on the surface of the flexible gear and wave generator is an important parameter of studying the deformation of flexible gear and flexible bearing outside the wave generator and is also a necessary condition for studying the fatigue damage of flexible gear under alternating load.In this paper,a 3D model of 32-type 80:1 harmonic drive is build.Based on the generalized Hooke law,a hypothesis of load distribution which is proved to be validity by using finite element simulation is proposed on the interface of flexible gear and wave generator.On this base,the mathematic model and the quantitative calculation formula of the load distribution on the surface of the flexible gear and wave generator are proposed which provide a basis for the dynamic analysis and the fatigue damage of harmonic gear drive.     

Modelling of a rolling contact problem with the viscoelastic material response included

This paper gives an approach to the study of a rolling contact problem where bodies in contact exhibit a viscoelastic behaviour. Taking the viscoelastic-elastic analogy into account, the numerical implementation to a certain class of viscoelastic solutions is presented first, followed by a simulation of the rolling contact problem. The simulation is based on the superposition of two special boundary problems, the former concerning a viscoelastic half-space loaded by a concentrated force, F(t), perpendicular to its surface, and the latter concerning a sphere loaded by two opposite concentrated forces.     

Modelling and simulation of dynamically integrated manufacturing systems

Fluctuations in demand patterns and products?? mixes, driven by continuous changes in customer requirements, are inducing significant changes on the operations of manufacturing organisations. How to respond to such changes rapidly and at minimum cost constitutes a major challenge for manufacturers. The DIMS project (Dynamically Integrated Manufacturing Systems) has developed an agent-based approach that enables manufacturing systems to be modelled using multi-agent systems such that optimal and timely responses to changes are generated from the interactions taking place within the multi-agents systems. This approach also incorporates a distributed discrete event simulation mechanism that enables ??what-if?? system configurations that have been generated through agent interactions to be evaluated dynamically for system restructure. This paper presents the approach with particular focus on the distributed simulation mechanism.     

Analytical modeling and simulation of a 2-DOF drive and 1-DOF sense gyro-accelerometer

In this paper, we present a new analytical model for frequency as well as transient analysis of a 3-DOF gyro-accelerometer system having 2-DOF in drive and 1-DOF in sense direction respectively. The model constructs lumped parameter differential equations by vector analysis associated with each degree of freedom that comprises Coriolis action, Euler’s action and action due to external acceleration along with biasing counterparts. These coupled differential equations are then solved explicitly in the frequency domain by taking their Laplace transforms. Based on these formulations, a thorough system analysis has been carried out keeping in view the various parameters and issues related to the device design. Furthermore, a discriminating scheme for time varying angular rate and linear acceleration by combining the structural model of a gyro-accelerometer with the demodulation and filtering processes to investigate frequency response of a micro gyro-accelerometer has also been presented by taking into account the presently derived settled transient solution of sense mode response. Finally we have verified the present model with MATLAB Simulink, showing their excellent agreement with each other.     

Development of a new spindle motor for a hard disk drive

A new spindle motor is developed with a sloped permanent magnet (PM) for a hard disk drive (HDD). In a conventional spindle motor, a pulling plate is installed at the stationary part under the rotating PM to pull down rotating bodies. This axial force is required for stable operation of the spindle motor using a hydrodynamic bearing. However, the pulling plate has considerable iron loss and a negative torque opposing the direction of rotation due to the induced eddy currents. Our proposed model has a sloped PM surface to generate the required axial force as well as torque without the pulling plate. Optimal design is carried out by a response surface methodology, and the new spindle motors are prototyped. The resulting electrical and mechanical performance of the prototyped motors is compared with that of conventional models, showing the possibility of adapting the proposed model for an HDD spindle motor.