Investigation of Wall Pressure Fluctuations in a Turbulent Boundary Layer by Large Eddy Simulation

Large eddy simulation (LES) was used to investigate the space-time field of the low Mach number, fully developed turbulent boundary layer on a smooth, rigid flat plate. The wall-pressure field simulated by LES was analyzed to obtain the pressure statistics, including the wall-pressure root-mean square, skewness and flatness factors, which show the wall pressure distribution was not Gaussian. The profile of the auto-power spectral density and the contour of the streamwise wavenumber-frequency spectral density of wall-pressure were plotted. The "convection ridge" can be observed clearly and the convection velocity can be calculated from the location of the convection peak.     

机房管理系统的Web查询及安装

博士特机房管理系统具有比较全面、实用的功能,本文通过对机房管理要求、系统结构的分析,论述了该系统的Web查询方式模块的分析和安装等实际应用过程中的问题并提出了相应的方案。     

Study on Distributed Motion of Self-Reconfigurable Robot Based on Local Rules

The eigenvector of a module with six adjacent module's state was constructed according to self-reconfigurable robot M-Cubes and the configuration of system was expressed with the eigenvectors of all modules.According to the configuration and motion characteristics of the modules,a 3-dimension motion rule set was provided.The rule sets of each module was run according to eigenvector of the module after the motion direction of system decided and motion rules were selected.At last,the rapid and effective motion and metamorphosis were realized in system.The rule sets are operated on three systems and the distributed motion of system is fully realized.The result of simulation shows that the 3-dimension motion rule sets has perfect applicability and extensibility.The motion steps and communication load of the modules increase with the module number in linear.     

Experimental Investigation on Contribution of CFRP Attachment to Durability of Reinforced Concrete Structure Subjected to Chloride Attack

The function of externally-bonded carbon fiber reinforced polymer （CFRP） in preventing chloride from entering into concrete is verified by experiment. The results show that externally-bonded CFRP can be considered as a part of corrosion prevention system of strengthened concrete structures subjected to chloride ingress, and the contribution of CFRP should be considered in evaluation of durability of reinforced concrete structures with externally-bonded CFRP. With the effective shielding function of CFRP considered, an equation for residual lifetime prediction of concrete structures with externally-bonded CFRP is derived from Fick＇s dispersion law. CFRP has two functions for coastal concrete structures, including strengthening and increasing durability as part of corrosion prevention system.     

微型扑翼飞行器空气动力学研究进展

微型扑翼飞行器(FMAV)作为一种新概念的航空器,有着广泛的功能和用途,已经受到了各国的高度重视.综述了国内外对微型扑翼飞行器的低雷诺数空气动力学问题的研究现状及未来的发展趋势,讨论了目前研究中需要解决的一些关键技术.在此基础上,总结出今后研究的重点,并为微型扑翼飞行器的设计提供了参考依据.     

一种基于视频虚拟检测线的交通流参数检测方法

实时交通流参数检测在智能交通系统中起着重要的作用。参数检测有多种方式,其中基于图像处理的视频车辆检测方式近年来发展很快,由于它具有检测区域大、系统设置灵活等突出的优点,已成为智能交通系统领域的一个研究热点。车辆的检测基于车道,在每个车道设置两条虚拟检测线来检测交通流参数,虚拟检测线的作用类似于电磁感应线圈。系统通过对视频虚拟检测线的预处理将二维的数字图像转化成一维的检测信号,减小了运算量,降低了运算负荷。提出的基于视频虚拟检测线特征的交通流参数检测系统已经在PC机上用VC 6.0实现,并对不同典型天气条件下的交通流视频进行了实验,实验结果表明该系统具有较高的车流量统计精度。     

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通过对ITS 投资项目的费用效益分析的系统研究，提出了建立ITS 投资项目费用效益分析的框架和技术流程的具体步骤，阐述了评价指标的计算方法、方案的可行性评价和方案选优等内容，研究了费用和效益的划分和估计方法. 另外，本文提出了不确定性分析的概念和方法，并对敏感性分析和概率分析进行了重点研究. 结合IDAS 软件，通过示例论述了上述方法的技术实现.     

Development of an Autonomous Flight Control System for Small Size Unmanned Helicopter Based on Dynamical Model

It is devoted to the development of an autonomous flight control system for small size unmanned helicopter based on dynamical model. At first, the mathematical model of a small size helicopter is described. After that simple but effective MTCV control algorithm was proposed. The whole flight control algorithm is composed of two parts: orientation controller based on the model for rotation dynamics and a robust position controller for a double integrator. The MTCV block is also used to achieve translation velocity control. To demonstrate the performance of the presented algorithm, simulation results and results achieved in real flight experiments were presented.     

柴胡皂苷d对大鼠实验性肝癌形成的预防作用

目的研究柴胡皂苷d(saikosaponin-d,SSd)对大鼠实验性肝癌形成的预防作用。方法采用间断小剂量二乙基亚硝胺(diethylnitrosamine,DEN)灌胃诱发大鼠肝癌模型,将90只清洁级雄性SD大鼠随机分为5组:正常对照组(10只)、肝癌模型组(20只)、SSd大、中、小剂量组(2.0、1.5、1.0 mg/kg,各20只),SSd治疗组在建立肝癌模型的同时,腹腔注射不同剂量的SSd,实验16周后停止给药,实验第18周处死所有大鼠,比较各组大鼠体重的改变,检测血清肝功指标丙氨酸氨基转移酶(alanine aminotransferase,ALT)、天门冬氨酸氨基转移酶(aspartate aminotransferase,AST)、碱性磷酸酶(alkaline phosphatase,ALP)、γ-谷氨酰转肽酶(γ-glutamyltransferase,GGT)、α-L-岩藻糖苷酶(alpha-L-fucosidase,AFU),并进行肝脏病理组织学检查。结果SSd各剂量组与肝癌模型组比较,血清各项肝功指标水平明显下降,差异有统计学意义,特别是SSd大剂量组(P<0.01);同时SSd治疗组与肝癌模型组相比,肝脏病理组织学镜下观察,癌细胞分化程度高,异型性低。结论SSd对大鼠实验性肝癌形成具有一定的防治作用。     

怀牛膝皂甙A对离体大鼠子宫兴奋作用机理的研究

用消炎痛和氯丙嗪作阻断剂，以子宫收缩曲线下面积（UCA）为指标，分析怀牛膝皂甙A对大鼠离体子宫兴奋作用的机理。结果表明，实验前给大鼠用消炎痛（75mg／只）灌胃或浴槽内加消炎痛（20mg／L），均可明显减弱怀牛膝皂甙A对大鼠离体子宫的兴奋作用。氯丙嗪（0．5mg／L）也可明显减弱怀牛膝皂甙A对未孕、已孕大鼠离体子宫的兴奋作用。提示怀牛膝皂甙A的子宫兴奋作用可能与5－HT及PG的合成与释放有关。