泥沙淤积物颗粒排列结构的分形模式研究

以河道、水库泥沙淤积物孔隙率问题为背景,用分形理论和计算机模拟方法研究了颗粒紧密排列模式CAPP(Close Arrangement Pattern of Particles)的图样特点。研究指出,CAPP是介于规则分形和统计分形之间的准自相似结构,用作者提出的孔隙率衰减过程类比法,得出其分形维数介于1.26和1.63之间,其最好估计值为D_H=1.4649。根据CAPP的级配特点,还对天然淤积物的孔隙率变化范围作了初步解释。     

Dimensional Synthesis Design of Novel Parallel Machine Tool

IntroductionIn recent years,the kinematics design theory ofparallel machine tools(PMT) has been attractingmuch attention from industry and researchcommunities[1,2 ] . The dimensional design is oneimportant part of the PMT kinematics designtheory.　 The approaches in previous work on dimensionaldesign of PMT may be classified into twocategories. One category is local optimal designwhich focuses on finding a family of dimensionalparameters generating an isotropic configuration,that is,a conf…     

流体网络模块化图形建模软件FLOWNET在600MW仿真机中的应用

６００ＭＷ火电机组模拟培训装置中的流体网络模块化图形建模软件包ＦＬＯＷＮＥＴ适用于任意拓扑结构的热工流体网络系统，只需把系统的网络结构以图形方式输入，便能自动生成网络模型程序。软件包界面开放，使用方便、灵活，是电站仿真建模的强有力工具     

无穷范数下的目标状态融合方法

给出了一种无穷范数意义下的状态估计线性组合的最优融合准则,在分布式雷达网数据处理模式中,通过利用各传统传感器输出的观测序列,对目标进行串上,将判定源于同一目标的状态估计值进行融合,得到更精确的目标状态和航迹,给出了实际数据的实验结果。     

低浓度颗粒流Boltzmann方程的同伦分析方法解

同伦分析方法(homotopy analysis method, HAM)是求解强非线性问题的有力手段. 针对颗粒流的动理学理论中的非线性微分积分方程——?Boltzmann方程, 采用 HAM方法选取局域Maxwell速度分布函数作为初始猜测解, 得到了低浓度颗粒流的Boltzmann方程的一阶近似解, 与传统的Chapman-Enskog方法得到的一阶近似解表达式的结构一致, 初步显示了HAM方法求解Boltzmann方程的有效性, 为一般Boltzmann方程的HAM方法求解奠定了基础.     

液体爆炸分散过程中界面破碎的实验研究

设计了一种有上下平面约束的液体爆炸分散装置, 通过阴影照相获得气液界面破碎形态变化的时间序列, 并应用平面激光诱导荧光(PLIF)得到了径向膨胀液体环内诱导的荧光照片. 采用二维图像处理、分形几何和数值模拟相结合的方法, 较系统地分析了实验结果. 最后, 讨论了液体环及其气液界面运动数学模型建立中的问题.     

Mobile Robot Control Based on Dynamic Potential

An efficient method is presented for implementing mobile robot perception-action behaviors, based on time-varying environment potential field approach. First, in this paper, the concept of dynamic potential U(x,y,z,t) is proposed for representing the environment of a mobile robot, and the form of U(x,y,z,t) is deduced, and then the velocity control of the vehicle with two wheel is directly calculated by transition function T of U(x,y,z,t). Finally, the perception-action layer is successfully implemented for avoiding collision, wandering, and integrating path planning and steering control on THMR-Ⅱ (TsingHua university Mobile Robot system). Based on sonar array signals, the experimental results are given to show that THMR-Ⅱ has better reflexive function, real-time obstacle avoidance, adaptablity and robustness for complex environments.     

具有良好运行特性的新型池窑结构设计

传统池窑中玻璃液的流动是自然对流控制下的混合对流，流型靠温度制度建立，稳定性差，对控制的要求高。为了改善玻璃熔制质量，剖析了传统池赛结构与运行特性的缺陷，针对性地提出了一种能克服其缺陷的新型池赛结构。用数值模拟对新池窑和传统池窑的运行特性进行了分析比较。这种新型池窑将澄清部由原来的深池改为浅槽，从而可用强迫流动取代原来的混合对流组织玻璃液澄清，因而具有稳定性好，易控制等优点。     

Simulation of EUV Imaging and 3-D Cone-Beam CT Reconstruction on the Plasmasphere

A three-dimensional(3-D) phantom for the density distribution of the plasmasphere is established .The imaging processes of the extreme ultraviolet(EUV) Imager are computer-simulated,in which the Earth shelter is treated as a main problem.A modified ART method is devised to resolve the incomplete data reconstruction problem to validate and evaluate the proposed methods.The cone-beam EUV data are simulated based on the 3-D phantom from both a circular and semi-circular trajectories.Quantitative reconstruction...     

利用对等网技术实现证书作废信息分发

证书作废信息的分发是限制公钥基础设施大规模部署的一个重要因素 .回顾了主要的证书作废信息分发方案 ,结合对等网技术 ,提出一个新的证书作废信息分发方案 .新方案大大降低了目录服务器的性能瓶颈和单点失效的风险 ,减少了证书作废信息分发的时间延迟