Volume 14    Number 9    (2002)

　

Title Author Abstract
Constructing the Robust Estimation Models by Numerical Differentiation and the Simulations for Their Applications YANG Yi-kang, ZHU Zhuan-min, SUN Guo-ji, HUANG Yong-xuan     Researching the characters of macro motion, numerical differentiation is introduced to describe dynamics of unknown kinematics process, then the filtering model of numerical differentiation (NDFM) and the combined filtering-predicting model of numerical differentiation (NDFPM) are constructed. Even though the dynamics of the process to be estimated is unknown, robust and simply models can be created by this approach for various applications, and it is easy to select appropriate estimation algorithms for satisfied estimation quality. The states of control-system disturbed by unknown inputs are restructured by NDFM for feedback and compensating disturbances; the present-predictive estimation of kinematics parameters are captured by NDFPM for tracked object with unknown dynamics. Simulation results show that NDFM and NDFPM are robust models to obtain precise estimation.
A Review of Importance Sampling JIN Guang     Importance sampling is one of the most important methods of improving sampling efficiency. It has been widely studied and applied in the analysis of communication networks, aviation and spacecraft systems, automatic control system, etc., because of its applicability and facilitation. This paper describes the difficulty of rare-event probability estimation using digital simulation method in the view of computation complexity, and focuses on the principles and construction methods of importance sampling plan. Realization and applicability of some optimized sampling distribution construction techniques such as stochastic optimization method, large deviation principle based techniques, failure biasing method and splitting method are summarized. Based on the discussion a knowledge based sampling distribution construction methodology is established. This will help to solve the sampling efficiency in digital simulation especially for high dependent system reliability analysis.
Modeling and Analysis of a Self-Maintenance Mechanism of States ZHOU Xiao, CHEN Ming     A self-maintenance mechanism of the state of resource usage in Client/Server System over wide area networks is put forward. Client retains the set of parameters about its usage of resource and related states. At the same time, it passes the set of parameter on server periodically. Thus the robust of application system and the consistency of state parameters can be attained. The Petri Net based Modeling of the Client/Server System that adopts this mechanism is described and the analysis of Self-Maintenance in this kind of system are also provided. Finally, the application of this mechanism is introduced.
Mining Linguistic Valued Association Rules ZOU Xiao-feng, LU Jian-jiang, SONG Zi-lin     Mining linguistic valued association rules is an important issue of quantitative association rules. The information of membership hasn’t been enough considered in the mining algorithm that we proposed before, so we propose the improved algorithm for mining linguistic valued association rules. In this algorithm we enough consider the information of membership, but the algorithm efficiency is not so high. In order to enhance the efficiency, a variable threshold is introduced and we propose an eclectic algorithm for mining linguistic valued association rules. The eclectic algorithm can save memory and time at the cost of losing few information of membership.
A Special Algorithm for Enhancement of Cosine Frequency Modulation Signals GUO Ye-cai, ZHAO Jun-wei, CHEN Hua-wei     When we use the conventional LMS-based ALE (adaptive line enhancement) algorithm to improve ability of underwater detection system to detect underwater target, there are three disadvantages: performance of handing Gaussian noise is bad, ability to trace time-varying signals is weak, and there will not be the ability to trace time-varying signals when the step size is zero. For greatly reducing these three disadvantages, we developed higher-order cumulant-based leakage-variable step size quasi-LMS adaptive line enhancement algorithm using the performance of cumulants in suppressing Gaussian noise and the advantages of leakage LMS algorithm and variable step size LMS algorithm, and analyzed its principle home. Based on the measured data radiated by the underwater moving-target, the enhancement process of cosine frequency modulation signals is dynamically simulated by the proposed algorithm. The simulation results show that the proposed algorithm can effectively overcome the shortcomings of the traditional LMS-based ALE algorithm and has a great capability of suppressing Gaussian colored noise and the performance of tracing time-varying signals. Accordingly, the research, in the paper, provides a new technical means for the recognition and detection of underwater moving-target.
A Kind of Coordinate Conversion Strategy for PPI Radar Indicator Simulation LIU Cui-hai, WANG Wen-qing, YUAN Man     The issue of polar coordinate-orthogonal coordinate conversion, which is a key factor of the system, may be encountered inevitably as simulating traditional PPI radar indicator on raster scan display. For polar coordinate-orthogonal coordinate mapping each other and fast-running of the system, the realization of reordering screen pixel point lattice on raster scan display according to characteristic of polar coordinate by endowing with multiple attributes is discussed in this paper. A fast table-lookup mapping method is then designed. By this mapping method, the real time coordinate conversion and processing of the echo signal become possible to perform for an ordinary PC.
Study of Key Techniques of CGF System Based on HLA WANG Hui-xia, ZHAO Xin-jun, WANG Xing-ren     To develop simulation system based on the new distributed simulation system standard, that is, high level architecture (HLA), a prototype system has developed. First characters and constituents of High Level Architecture is presented in section two. The architecture characters of CGF simulation system and key technologies of CGF system based on HLA are analyzed in the third section. A CGF prototype system on the basis of the key technologies discussed in section two and section three has been developed. The development of the prototype system plays an important role in the future CGF system research and application. At last, future work need to focus on the CGF system development is presented.
Simulation of Air-Raid Cruise Missile in Air Defense Training LONG Tao, CHEN Jing, FENG Qing-tang, SHEN Lin-cheng     With the background of an air defense training system, simulation models of many kinds of cruise missile are established, including physical model and three-dimensional model. Based on mission planning technique and DIS, a air-raid cruise missile simulation system is developed. The simulation system is a computer generated forces (CGF) system, and it can provide virtual air-raid forces as enemy for antiaircraft forces in air defense training. Three-dimensional visualization of simulation process is realized in the system.
Distributed Parallel Optimization Computation Environment Based on Matlab ZHANG Fan, SHAO Zhi-jiang, ZHONG Wei-tao, QIAN Ji-xin     A distributed parallel optimization computation environment based on matlab is proposed. After details of parallel computation environment are discussed, the architecture of distributed parallel optimization computation environment is analyzed. Then four kinds of parallel functions are discussed, which include functions of initialization, sending and receiving data, computation, sending and integrating results. A parallel SQP is implemented using these four kinds of functions. Pseudo codes demonstrate the efficiency of this implement.
Introduction of a Virtual Assembly Supported System ZENG Li,ZHANG Lin-xuan,XIAO Tian-yuan     Virtual assembly is one of the key technology of virtual manufacture. A virtual assembly supported system (VASS) is developed for the application, with which a product can be analyzed, simulated and pre-assembled virtually, meanwhile its assemblability can be verified and improved dramatically. The structure of VASS and main key technology are introduced, including assembly modeling, sequence planning, the presentation of assembly\disassembly move, and interference checking. The system has been applied effectively to some engineering projects.
Study on AC Electromagnetic Tracker for Human-Computer Interaction LIU Yue, WANG Yong-tian, HU Xiao-ming     Electromagnetic tracking systems are widely used in Virtual Reality and computer simulation system to measure the attitude and position of the user’s hand or head to perform Human-Computer Interaction. The shortcomings of the present direct current electromagnetic tracker are analyzed and an alternative current electromagnetic tracking system with the alternative current source is proposed. The structure of the proposed system is studied and the iterative digital correlation algorithm used for calculating the received data is deducted. The relationship between the parameter and the performance of the algorithm is discussed. The simulation result proves the effectiveness of the proposed algorithm. Actual alternative current electromagnetic tracking system can be designed on the basis of the theoretical analysis of this paper.
Research on the Methods of the Cooperative Modeling and On-line Optimization about the Procedure of Virtual Enterprise YAN Ru-zhong, CHEN Yun, ZHANG Kai-tao, FANG Ming-lun     Based on Internet/Intranet, the methodology of the cooperative modeling and on-line analysis and dynamic optimization about the agile virtual enterprise are discussed. The closed loop system of the modeling and management and analysis and optimization is set up on the integrated platform of CSCW and workflow. Therefore, it can support on-line optimization and make it easy to refigure the process of the virtual enterprise continuously to adapt the virtual enterprise to inside and outside environment changing. This methodology can make it success in the example of agile manufacturing.
Discussion on Intelligibility of Virtual Actor in Behavior Simulation QIN Shuang, ZHANG Fan, CHEN Ying, FENG Xiu-Juan, ZHENG Guo-Lei, WEN Wen-Biao, SUN Hong-San     For evaluating matching and harmony between human and environment in virtual human-machine- environment research as well as static and limbs or trant moving property in ordinary sense of virtual actor, the performances to realistically simulate a process of performing mission are needed. Operation of target object after sequence movements is usually completed by hand or foot. Based on analyzing movement structure and control of human body, an approach to implement walking, sitting down-standing up, stooping, turning around, squatting down of virtual actor is discussed. simulation step of virtual actor to executing composite movement and operating behavior is proposed and trial test examples are given.
Research on Graphic Supporting Platform for Power System Dispatcher Training Simulator DONG Zhao-xia, WANG Cheng, CHEN Qing-hua, FAN Dou     For filling up the shortage of classical graphic system, the design principle and the function needs of the graphic supporting platform for power system dispatcher training simulator (DTS) are defined; the coherence, open attribute, independency and error bearing are fully considered. The main modules and realization method of the graphic supporting platform including the graphic editor module, the displaying module in DTS and the graphic printing module are systematically discussed. A graphic supporting platform has been developed and applied in a actual DTS system.
Study on Shell Stop Mechanism Abrasion in XX Breech System Based on Virtual Prototype Technilogy DU Zhong-hua, WANG Xing-gui, DI Chang-chun, HUANG Tao     Based on virtual prototype platform of XX breech system featured by contact and built ADAMS, this paper analyses the effect of shell stop mechanism abrasion in the breech system on shell stopping motion, brings forward the differences between even abrasion and uneven abrasion, and points out that the traditional understanding to the problem only be a subjective image and the actual uneven abrasion can be studied with virtual prototype method. Finally the feasibility of an improvement method on the breech system was researched based on uneven abrasion.
Research on Virtual Reality System for Color Matching Designing in Crew Module of Manned Spacecraft ZHOU Qian-xiang, QU Zhan-shen, JIANG Guo-hua, WANG Chun-hui     A pleasant decoration of crew module is one of important ways for improving the human-rating of manned spacecraft and ensuring its safety and reliability. At first, the hardware components of the virtual reality system is introduced, then the software designing methods and some computation models are expounded in detail, on the basis of which this system is applied in a color matching choice ergonomic experiment of a virtual crew module. Finally, some views are put forward for discussion.
Wave Simulation Based on Ocean Wave Spectrums YANG Huai-Ping, SUN Jia-guang     In recent years, simulating natural phenomena has always been one of the most challenging tasks in computer graphics. As one of its most important parts, simulating water and wave has been given more and more attention. Some existing methods try to solve complex Navier-Stokes equations, and some others try to construct special functions to model the shape of water waves individually. This paper presents a method of wave simulation based on ocean wave spectrums, using the observation and research results of oceanography, such as frequency spectrums and directional spectrums of ocean wave. Our results show that the method is efficient and effective in wave simulation.
The VRML Automation Development Technology in Cortona Interpreter JIN Hui, SHI Min     VRML automation, which integrates OLE automation into VRML, is a fire-new virtual reality application development technology. It provides a program interface, through which application in high-level language can access and operate VRML objects directly. Using this technology, it will be easier to develop a flexible and efficient emulation system that combines the advantages of VRML in virtual reality modeling and 3D scene transformation and the integrated functions of high-level language such as friendly GUI, network communication and the ability to access databases. In this paper, we will introduce the VRML automation technology based on Cortona VRML interpreter through a Delphi example.
The Research and Implementation of Constructing Complicated Interactive Virtual Scenes LI Zhen-bo, MENG Xiang-xu, XIANG Hui     According to the characteristics of complex virtual reality systems, some technical problems about constructing complicated virtual scenes and multimodal interactive navigation are discussed in this paper. We give the procedure of constructing virtual scenes first, then some related technologies we utilized including 3D data acquiring, model building, complicated virtual scenes construction etc. are discussed. Furthermore, we also discuss some multimodal interactive technologies including hand gestures based navigation and stereo displaying. The above technologies were incorporated into the design and implementation of Digital Archaeological Museum and virtual campus of Shandong University. Experimental results show that our VR system could provide users satisfactory immersed experience.
View Dependent Subdivision LOD and its Application in Virtual Endoscope HE Hui-guang, TIAN Jie, ZHAO Ming-chang, LI Guang-ming, ZHANG Xiao-peng     Construct the level of details model with view-dependent subdivision, and apply it to virtual endoscope. First we simplify the mesh in hierarchy to get the base mesh, and then parameterize the mesh to map the original mesh to the base mesh, and use the view-dependent subdivision to resample. In the implementation of the view point principles, we adopt octree to index the change of the view point, and the model can be reused in the dynamic change. The experiments show that our method is efficient and is easy to implemented, and the model can be rendered in real time to meet the requirement of virtual endoscope.
The Computer Animation Simulation of the Movement of the Liquid-metal Molecular JIANG Zhi-fang, ZHANG Ru, LI Yu-chen, XU Wei     The paper presents a 3d computer animation simulating system for the movement of the liquid-metal molecular. It is used to simulate the structure evolvement and movement of the liquid-metal molecular in non-crystal state after having been cooled down instantly. The system can show us in the computer screen the movement state of every molecular which locates within the central single cell gained by experiment and calculation. The system can let us observe the molecular with different view point and can also let us follow some certain molecular tracks in order to understand their speciality we are interest in. The ways of developing this system and the some detail methods for implementing the above functions with VC++ and OpenGL were discussed in the paper.
Flight Course Replay And Simulation Base on OpenGL FU Zhan-ping, DI Ya-zhou, SHANG Xi-liang, QIU Zhi     This paper proposes a method about research of certain aircraft flight course replay and simulation based on Open graphics language (OpenGL). It combined with computer graphic and multimedia technology, and can generate flight course fast and realistically. And analyzed how to realized creating model, simulation and dynamic drive using OpenGL for research of flight course replay and simulation.
New Content-Based Semi-Fragile Watermarking YI Kai-xiang, SUN Xin, WANG Dao-shun, SHI Jiao-ying     In this paper we propose a semi-fragile watermarking scheme, which can be used for image authentication. Let the original image be performed by the l-level discrete wavelet transformation. Then the approximate wavelet coefficient matrix of the original image and the chaotic sequences are used to generate the content-based and secure watermark. The watermark is embedded into original image by using the technique of HVS. The tamper detector can identify the tampered region from the received watermarked image which may be undergone tamper attacked. Experimental results are excellent.
A Method of Rendering Clouds with Perlin Noise QI Yue, SHEN Xu-kun, DUAN Mi-yi, CHENG Hui-lin     Clouds are one of the most important parts in realistic 3D virtual environment. For many researchers, how to model and render clouds is a very interesting problem in computer graphics. This paper first introduces the concept of Perlin noise and the method of generating Perlin noise. We used Perlin noise to create 3D clouds images. Then we made use of image-based rendering techniques to render clouds in 3D virtual environment. With our method, the position and direction of clouds can be changed according to the user’s viewpoints when he is wandering in the virtual environment.
An Algebraic Condition for the Positional Relationship of an Ellipse and a Parabola (Hyperbola) SHEN Li-yong, LIU Yang     In many scientific areas such as computer animation, computer graphics, computer aided geometry design and robot, it is very common to detect the positional relationship of several entities. We derive an algebraic condition (based on the generalized characteristic polynomial) for detecting the positional relationship of a planar ellipse and a planar parabola (hyperbola) by considering all the cases: separation, exterior contact, intersection, interior contact and inclusion.  The algebraic condition can be represented by the distribution of the roots of the generalized characteristic equation of the ellipse and parabola (hyperbola). The criterion is simple and effective, and easier than old methods.
A Novel Embedding Game of Blind Watermarking Against Rotation and Shearing WANG Dao-shun, DiLian Yang, DAI Yi-qi     By studying the watermarking attacking, we propose a novel embedding game for the blind watermarking. This game is based on the extraction of the whole watermarking as follows: the cover image is split into many shares with respect to its center, each share of which can be exactly overlapped the comparable one by the some rotations. This game is robust to rotating and shearing. The game that integrates the symmetric game and the multi-embedding is given. The robustness to rotating and shearing of angles is also proved. Moreover, we present a method to realize the game and discuss the relationship between the robustness and the payload in the scheme. The method is independent of the transformation domain and the embedding algorithm. Our test results show that the game is valid.
Real-Time Simulation of Natural Phenomena YIN Yong, JIN Yi-cheng, REN Hong-xiang, ZHANG Xiu-feng     It is difficult to simulate natural phenomena such as: rain, snow, lightning etc in real-time in simulation system using FBM and L-system because they are irregular, dynamic and random. Particle system is adopted in this paper to simulate natural phenomena including snow and rain in real-time. The approach has been implemented and applied in simulation system of navigation successfully.
Non-Photorealistic Rendering in Chinese Painting of Animals Jun-Wei Yeh, Ming Ouhyoung     A set of algorithms is proposed in this paper to automatically transform 3D animal models to Chinese painting style. Inspired by real painting process in Chinese painting of animals, we divide the whole rendering process into two parts: borderline stroke making and interior shading. In borderline stroke making process we first find 3D model silhouettes in real-time depending on the viewing direction of a user. After retrieving silhouette information from all model edges, a stroke linking mechanism is applied to link these independent edges into a long stroke. Finally we grow a plain thin silhouette line to a stylus stroke with various widths at each control point and a 2D brush model is combined with it to simulate a Chinese painting stroke. In the interior shading pipeline, three stages are used to convert a Gouraud-shading image to a Chinese painting style image: color quantization, ink diffusion and box filtering. The color quantization stage assigns all pixels in an image into four color levels and each level represents a color layer in a Chinese painting. Ink diffusion stage is used to transfer inks and water between different levels and to grow areas in an irregular way. The box filtering stage blurs sharp borders between different levels to embellish the appearance of final interior shading image. In addition to automatic rendering, an interactive Chinese painting system which is equipped with friendly input devices can be also combined to generate more artistic Chinese painting images manually.
Study on Effectiveness Top Analysis of Air-to-Ground Aviation Weapon System ZHANG An, ZHANG Yao-zhong     Firstly the combat mission of air-to-ground aviation weapon system was programmed. Then the combat flight model of group air-to-ground aviation weapon system was established. Finally the overall indexes and frame of group air-to-ground aviation weapon system were set up on the base of above. The relation between top index and every flight segment of effectiveness was given so as to study the combat effectiveness of group air-to-ground aviation weapon system. Using this model we get an effective way to evaluate combat effectiveness of group air-to-ground aviation weapon system.
Simulation for Tactical Missile's Stabilization System Based on the Simulink and C/C++ Mixed Program Technique DONG Xi-jun, LUO Zhi-jun, HONG Xing-chang     In order to be convenient for the mathematical model's foundation, to make use of the already existing code source and improve the programming efficiency in the research of the simulation for tactical missile's stabilization system, this paper completes the high-level visual and high-speed running digital simulation test by use of the Simulink and C/C++ mixed programming technique which can combine the merits of these two languages. This method is not only suitable for the digital simulation test, but also can be extended to the hardware-in-the-loop simulation test of the missile's stabilization system by adding some corresponding hardware and software. This method has high engineering practice value and popularization sense.
Servo Table Robust Control Based on Fuzzy RBF Neural Network WU Yun-jie, LIU Jin-kun, LIU Qiang     Identification is realized by adopting fuzzy RBF neural network, control is realized by adopting complex control. The control parameter of complex control is modified by the identification results. The result of controlling indicates the method gives good identification ability and controls precision, and has high robustness.
Research on the Lunar Rover Simulation Platform LUO Xun-ji, SUN Zeng-qi     The lunar rover simulation platform discussed in this paper provides a general virtual test-bed for lunar rover research and development. The purpose of the simulation is to test the architecture, control, and sensors of rover systems. This simulation platform provides a Terrain Builder to create lunar terrain modules, and an Environment Editor to utilize these modules to create and edit virtual lunar environment. Based upon the COM technology, this simulation platform allows various rovers to join simulation, and, due to the characteristics of COM, this system is a distributed simulation system. The simulation platform and rover system can run on different computers connected with network.
Research on Design Scheduling of the RVD Simulation System WANG Hua, TANG Guo-jin     In order to establish the Rendezvous and Docking (RVD) simulation system, the scheme of a computer simulation system, which is expansible, is put forward in this paper. After the dynamic models are given, the scheduling of the RVD computer simulation system is designed by using the object-oriented technology, and a general framework of simulation system is given. As an example, a simple object-oriented RVD simulation system is built at the end of this paper.
Simulation of Temperature Field of Copier Paper Based on Wavelet Finite Element Method YANG Sheng-jun, MA Jun-xing, XUE Ji-jun, HE Zheng-jia     The simulation of temperature field of copier paper in the copier fusing is very important for improving the fusing property of reprography. The temperature field of copier paper varies with high gradient when the copier paper moving through the fusing rollers. By means of conventional shaft elements, the high gradient temperature variety causes the oscillation of the numerical solution. Based on the Daubechies scaling functions, a kind of wavelet-based element is constructed for the above problem. The temperature field of the copier paper moving through the fusing rollers is simulated using the two methods. The comparison of the results shows the advantages of the wavelet finite element method, which provide a new method for improving the copier properties.
Simulation Design on the Reduced-Scale Model Prototype of an Underwater Launch System DUAN Hao, HU Zong-wu, YANG Cheng-shi, LI You-ming, WANG Yun     Based on a type of vane pump launch system being developed, the main similar criterions, to which the system adheres in a launch process, are determined. The main parameter values, which are gotten from a typical underwater launch process in a real analogous system, are defined as the target in comparable characters. Basing on that the energy is tenth of that needed in the real launch system, and on some definite binding conditions, the simulation design on the reduced-scale model prototype is done with a group of relevant similar criterion. The conclusion is given that the outcome resulted from simulation design is ideal.
Constructing & Simulation of a Dynamic Model of Hoisting System Driven by PMLSM Based on Neural Network WANG Fu-zhong, JIAO Liu-cheng, ZHANG Xiang-wen, YUAN Shi-ying, WANG Li     The hoisting system driven by Permanent Magnet Linear Synchronous Motor (PMLSM) is different from the traditional hoisting model in construction and control mechanism. It’s difficult to reflect the kinetic characteristics of the system accurately on the base of analytical model because of the influence of many factors, such as the ferrite core’s disconnection, the asymmetry of three-phase winding and the big fluctuating of parameter in the course of work etc. In this paper, a dynamic model of this system was constructed on the basis of BP network, meanwhile it’s mainly introduced about the network’s learning algorithm and the method of modeling, the gain of training data and selection of the network training parameter. Simulation result and experimental verification show that this model reflects the basic kinetic characteristics of the system more realistically than the analytical model. It has practical value in analyzing characteristics and control tactics of the system.
Neural-Network Control Based on Agile Missiles’ Inversion Dynamics SHI Xiao-rong, DONG Chao-yang, ZHANG Ming-lian     Neural-network control architecture based on agile missiles’ inversion dynamics is presented. It consists of two neural networks. The first neural network is used to represent the nonlinear inverse transformation. It is trained off-line using a mathematical model, which provides an approximate inversion that can accommodate the total flight envelope. The second neural network capable of on-line learning is required to compensate for inversion error, which may arise from nonlinear dynamics, approximate inversion, or sudden changed in aircraft dynamics. A stable weights adjusting rule for the on-line neural network is derived from Lyapunov theory, thus assuring the stability of the closed-loop system. A benefit is that the control system tends to be more robust. Apply the control system to an agile missile, the digital simulation results show its effectiveness.
Simulation Research on the Adaptive Variable Structure Control of Robot LI Shi-jing, WAN Jie-fa, FENG Zu-ren     This paper proposes a novel control scheme with focus on the uncertainty of the robot system, which use Adaptive Variable Structure Control (AVSC) theory on the trajectory tracking control of robot. And the robust gains are adjusted adaptively. The global asymptotic stability is validated by Lyapunov direct method. A smooth saturation function, which maintains system having same stable condition, is used to reduce the control chatter and transient performance of system. Simulation results show the estimated parameters are converged and the good robust and accuracy are obtained.
Research on Simulation System for Anti-Missile ECM QIU Jie, CHENG Ji-hong     One simulation system for anti-missile ECM is developed. This system is aimed at anti-ship missiles with terminal guidance radar and may work on a high performance PC. The model framework of the simulation system and the main factor in constituting the model are introduced. Some key problems in developing the system are discussed, such as the problem about combination of Simulink/Matlab and VC++, and the problem about changing ECM modality and ECM parameters in line.