SVG的电压定向控制算法仿真

针对电流控制方法在静止无功发生器SVG无功补偿上的缺陷,提出了一种先进的电压定向控制算法（VOC）. 首先介绍了VOC的基本原理,然后详细论述了电压定向控制的拓扑结构及无功电流与有功电流解藕过程,最后在MATLAB/Simulink的环境下进行了系统建模和仿真. 仿真结果表明,运行基于电压定向控制方法的SVG装置,系统将得到良好的动态特性,功率因数大大提高,弥补了传统电流控制的缺点,对于SVG的无功补偿效果提高具有重要的现实意义.     

用于飞机变频电网APF的补偿电流指令产生方法

针对飞机交流变频电网谐波抑制的需要及传统方法在变频条件下的不足,提出了一种基于正序基波滤波器的补偿电流指令产生方法。该方法从整体上分析了正序基波滤波器的特性,并利用正序基波滤波器分别滤除了电源电压和电流中的谐波和非正序成分,而后计算出电源的正序基波有功电流,由此得到补偿电流指令,检测过程中省去了低通滤波器。将该方法应用于三相电压不对称且有畸变的飞机变频电网的并联有源电力滤波器(APF)中,结果表明,采用该方法在整个基频变化范围内能实现对谐波、无功及不平衡电流准确而快速的检测和补偿,补偿结果符合MIL STD 704F和IEEE Std 519标准的要求。     

基于新型无功和谐波电流检测方法的APF仿真研究

结合基于瞬时无功功率理论的ip-iq检测方法和基于传统功率理论的闭环自适应检测方法两者的优点,设计一种新的检测方法,该方法具有较好的鲁棒性和动态响应速度。同时由于逆变器采用三桥臂电容中点式结构,对其直流侧电压的稳定和上下电容的均压控制作了分析,与无功和谐波电流检测结合起来形成了双闭环结构,进一步增强补偿效果,然后对指令电流的合成和其跟踪控制作了简要阐述。最后利用Matlab/Simulink对系统进行了仿真,验证了该方法的正确性和有效性。     

一种基于神经网络理论的谐波和无功电流检测方法研究

将自适应噪声对消技术用于谐波和无功电流检测提出了一种变学习因子的神经网络自适应谐波和无功电流检测方法.所提出的方法适用于有源电力滤波器的谐波和无功电流检测.理论分析和仿真结果证实了该方法的可行性.     

电流平均值谐波检测法的SIMULINK仿真研究

本文介绍了一种不使用滤波器的谐波电流检测方法——电流平均值法．给出了在Simulink环境下相应仿真模型的建立方法，并对其进行了仿真研究。结果不仅表明电流平均值检测法比传统滤波器法具有较快的动态响应，而且验证了所建立的仿真系统的有效性。     

有源电力滤波器谐波及无功电流的检测

准确、迅捷检测出系统电流中的谐波及无功成份，是保证有源电力滤波器（APF）能适时补偿的关键，由于传统检测方法系统复杂，所需器件多，因此从傅立叶变换出发，提出了一种新型的谐波及无功电流检测方法；基波有功分量剔除法，该方法由于算法简单，所用器件少，适时性较高，不仅能适用于单相电路，而且也适用于三相电路，理论分析和仿真研究表明，该方法能适时准确地检测出谐波及无功分量。     

基于Matlab有源电力滤波器APF的仿真研究

采用Matlab仿真软件中的Simulink,提出了并联型有源电力滤波器的一种仿真方法。仿真结果表明,使用该方法能将有源电力滤波器的工作过程及有关波形准确直观地显示出来,该方法可以用于动态抑制谐波,补偿无功功率,可以进一步应用于电网中。     

基于MatIab有源电力滤波器APF的仿真研究

采用MatIab仿真软件中的SimuIink,提出了并联型有源电力滤波器的一种仿真方法。仿真结果表明,使用该方法能将有源电力滤波器的工作过程及有关波形准确直观地显示出来,该方法可以用于动态抑制谐波,补偿无功功率,可以进一步应用于电网中。     

有源电力滤波器的预测电流控制方法研究

针对三角波电流控制方法和滞环电流控制方法的不足,详细分析并实现了有源滤波器预测电流控制方法.该方法具有控制精度高,响应速度快,主电路开关频率恒定等优点.理论分析和实验结果验证所提出的控制方法的有效性,基于预测电流控制方法的有源电力滤波器具有良好的工作性能.     

Experiments with Parallelizing Tribology Simulations

Different parallelization methods vary in their system requirements, programming styles, efficiency of exploring parallelism, and the application characteristics they can handle. For different situations, they can exhibit totally different performance gains. This paper compares OpenMP, MPI, and Strings for parallelizing a complicated tribology problem. The problem size and computing infrastructure is changed to assess the impact of this on various parallelization methods. All of them exhibit good performance improvements and it exhibits the necessity and importance of applying parallelization in this field.     

Snake Robot Obstacle-Aided Locomotion: Modeling, Simulations, and Experiments

Snakes utilize irregularities in the terrain, such as rocks and vegetation, for faster and more efficient locomotion. This motivates the development of snake robots that actively use the terrain for locomotion, i.e., obstacle-aided locomotion. In order to accurately model and understand this phenomenon, this paper presents a novel nonsmooth (hybrid) mathematical model for wheel-less snake robots, which allows the snake robot to push against external obstacles apart from a flat ground. The framework of nonsmooth dynamics and convex analysis allows us to systematically and accurately incorporate both unilateral contact forces (from the obstacles) and isotropic friction forces based on Coulomb's law using set-valued force laws. The mathematical model is verified through experiments. In particular, a back-to-back comparison between numerical simulations and experimental results is presented. It is, furthermore, shown that the snake robot is able to move forward faster and more robustly by exploiting obstacles.     

Large Deflection Analysis of a Thin Plate: Computer Simulations and Experiments

Many previous studies have conducted computer-aided simulations ofelastic bodies undergoing large deflections and deformations, but therehave not been many attempts to validate their numerical results. Thesubject of this paper is a thin clamped plate undergone large vibrationdue to attached end-point weight. The main aim of this paper is to showthe validity of the absolute nodal coordinate formulation (ANCF) bycomparing to the real experiments. Large oscillations of thin plates arestudied in the paper with taking into account effects of an attachedend-point weight and aerodynamic damping forces. The physicalexperiments are carried out using a high-speed camera and dataacquisition system. For numerical modeling of the plate, the absolutenodal coordinate formulation is used.     

X射线同轴相衬成像原理数值模拟及实验初探

主要对微焦点源X射线同轴相衬成像系统的系统参数进行了设计与讨论,并对结果进行了实验验证.根据实际选取X射线能量以及物体的折射率改变量和吸收因子来确定物体传输函数,从物体到探测面的距离、物体边缘渐变宽度等因素对图像可见度的影响进行分析,提出了改进分辨率方法并通过数值模拟得到验证.最后,在实验中对普通三角板进行相衬成像,并与其吸收衬度成像进行对比.实验结果表明,利用数值模拟的方法可以指导微焦点源相衬成像参数设计,同时验证了该实验仪器的相衬能力.     

利用七色光模拟白光杨氏干涉实验

以七色光为白光光源,基于Matlab软件,模拟了白光杨氏双孔和双缝干涉实验。结果表明,白光杨氏干涉的中央亮纹为白色,其余条纹则内紫外红;双孔、双缝干涉的条纹分别为双曲线族和平行直线族。模拟图像色彩连续而逼真,可应用于光学辅助教学等。     

3-D Snake Robot Motion: Nonsmooth Modeling, Simulations, and Experiments

A nonsmooth (hybrid) 3-D mathematical model of a snake robot (without wheels) is developed and experimentally validated in this paper. The model is based on the framework of nonsmooth dynamics and convex analysis that allows us to easily and systematically incorporate unilateral contact forces (i.e., between the snake robot and the ground surface) and friction forces based on Coulomb's law of dry friction. Conventional numerical solvers cannot be employed directly due to set-valued force laws and possible instantaneous velocity changes. Therefore, we show how to implement the model for numerical treatment with a numerical integrator called the time-stepping method. This method helps to avoid explicit changes between equations during simulation even though the system is hybrid. Simulation results for the serpentine motion pattern lateral undulation and sidewinding are presented. In addition, experiments are performed with the snake robot ldquoAikordquo for locomotion by lateral undulation and sidewinding, both with isotropic friction. For these cases, back-to-back comparisons between numerical results and experimental results are given.     

SVG技术研究及其在地质图像解释中的应用

SVG是W3C推出的一种基于XML的网络图形标准,将地质图像解释的图形转换为SVG格式,使解释结果可以方便地在网上发布.研究了地质解释结果中的图形对象和SVG图形元素的映射方法,使用GDI+开发,编程实现了GDI+中图形对象到SVG格式的精确转换.此方法可以转换GDI+中的各种图形对象,以及文字信息和颜色.     

A Modular Self-Reconfigurable Robot with Enhanced Locomotion Performances: Design,Modeling, Simulations,and Experiments

This paper presents the design and implementation of a modular self-reconfigurable robot with enhanced locomotion capabilities. It is a small hexahedron robot which is 160 mm × 140 mm × 60 mm in size and 405 g in weight. The robot is driven by three omnidirectional wheels, with up and down symmetrical structure. The robot can perform rectilinear and rotational locomotion, and turn clockwise and counterclockwise without limitation. A new docking mechanism that combines the advantages of falcula and pin-hole has been designed for attaching and detaching different modules. The communication and image data transmission are based on a wireless network. The kinematics and dynamics of the single module has been analyzed, and the enhanced locomotion capabilities of the prototype robot are verified through experiments. The maximum linear velocity is 25.1cm/s, which is much faster than other modular self-reconfigurable robots. The mobility of two connected modules is analyzed in the ADAMS simulator. The locomotion of the docking modules is more flexible. Simulations on the wheel and crawling locomotion are conducted, the trajectories of the robot are shown, and the movement efficiency is analyzed. The docking mechanisms are tested through docking experiments, and the effectiveness has been verified. When the transmission time interval between the adjacent packets is more than 4 ms, the wireless network will not lose any packet at the maximum effective distance of 37 m in indoor environments.     

Development of a GPU Accelerated Terrain Referenced UAV Localization and Navigation Algorithm

This study focuses on localization and navigation of Unmanned Air Vehicles (UAVs) based on digital terrain map data. The solution to the Terrain Referenced Localization and Navigation (TERELONA) or Terrain Referenced Navigation (TRN) is described by using particle filter. In many UAV applications one of the most important points is to provide accurate location information continuously. TERELONA system can supply the air vehicle with the accurate position information with a bounded error. In this paper, the particle filtering method as an implementation of Bayesian approach to the terrain referenced localization and navigation is described. The radar altimeter measurements are used as an implicit representation of aircraft position. Whenever new measurements are taken from radar altimeter, they are compared to the Digital Terrain Map (DTM) data in order to fix a position. The solution is represented, in a Bayesian framework, by a set of particles with their corresponding weights. We have developed the terrain referenced localization and navigation algorithm based on the particle approximation. The proposed algorithm, which is developed in CUDA^TM, is also tested on the GPU environment using GPUmat software architecture. Thus, we can cope with the computational load of the very large initial horizontal position errors. The proposed algorithm has been implemented in MATLAB^TM environment and evaluated on simulated data. Simulations are conducted over an ASTER GDEM product which belongs to a region in northwest of Turkey. The simulation results are provided.