基于压力分布的高速列车气动力计算方法

基于径向基函数的气动压力插值方法和摩擦力计算模型,提出了一种可用于高速列车线路试验的气动力快速计算方法。该方法只需测得车体表面若干测点的压力,然后基于这些测点的压力值,使用径向基函数插值方法得到车体表面压力分布;并采用数值积分方法与平板边界层摩擦力计算模型能够快速得到气动压差力和气动摩擦力。列车附属部件几何外形复杂,难以通过插值方法获取表面压力分布;为此,基于八辆编组真实外形,给出了各附属部件对列车气动力贡献度,从而使本文提出的方法能够应用于线路试验和动模型试验。为验证计算方法的有效性,针对高速列车三辆编组简化外形头尾车流线型部分,采用数值计算方法对比分析了气动阻力和气动升力计算结果与计算结果;针对三辆编组风洞试验外形分析了气动阻力试验值和计算值。结果表明:提出的计算方法能够满足工程精度要求。     

An Investigation of Stimulating the Autoclave Curing Process of Resin Matrix／Fiber Reinforced Composite Material, Ⅰ ： Process model

A mathematical model is made which describes the curing process of composites constructed from continuous fiber-reinforced, thermosetting resin matrix prepreg materials, and the consoli-dation of the composite is developed. The model provides the variation of temperature distribu-tion, the entre reaction process in the resin, the resin flow and fibers stress inside the composite,and the void variation and the residual stress distribution. It can be used to illustrate the mecha-nism of curing process and optimize the cure cycle of composite material in order to ensure the quality of a product.     

现代建筑数字电子设备接地方式的探讨

针对现代建筑应设立的多种接地方式,从满足人身安全及设备安全运行的角度,首先就防雷接地、交流工作接地及安全保护接地应采取的接地方式进行探讨,着重就弱电控制系统存在的导电性电磁干扰和辐射性电磁干扰,分析其产生的机理并给出摒去干扰的有效方法。分析现代建筑多种接地方式之间存在的必然联系,给出安全有效的接地处理方法。     

矿区连续运行参考站选址分析

对连续运行参考站的选址问题进行了探讨,结合鲁西矿区连续运行卫星定位服务综合系统参考站的实际选址工作,论述了其选址的原则.采用TEQC软件时拟建参考站A和B的观测数据进行全面的质量分析,同时把分析的结果和已建成的C参考站的数据进行对比,从而确定出更适合作为连续运行参考站的站点.经对A参考站试运行期间的数据验证,所选参考站点完全满足参考站建设技术规范和矿区应用的需求.     

一种微弧氧化逆变电源控制系统

为满足微弧氧化工艺要求,设计出一种两级逆变式微弧氧化电源,介绍了该电源的控制系统.它以高性能DSP作为控制核心,通过调节输出两组4路PWM (脉宽调制)信号分别驱动前级功率逆变电路和后级斩波逆变电路.功率逆变电路采用有限双极性的控制方式以实现电压的调节,通过控制斩波逆变电路可以得到所需的各种电压波形.同时,该电源控制系统还具有过流、过欠压、过热、参数超限等故障诊断与保护功能.试验结果表明,该控制系统可以实现精密、稳定的电源控制,提高电源的适应能力.     

Cupric ion release and cytotoxicity for Yuangong Cu-IUDs and the release behavior of indomethacin for medicated 220 Cu-IUD

These years Yuangong copper-bearing intrauterine devices （Cu-IUDs） have been used because of less side effects in use. The corrosion of copper is essential to the success of contraception, and the release behavior of indomethacin from medicated Cu-IUD is related to its therapeutic effect. In this study, analytical methods were established to investigate the release behavior of cupric ion of three kinds of Yuangong Cu-IUDs and indomethacin of medicated Yuangong 220 Cu-IUD. Cu-IUDs were incubated in simulated uterine solution （SUS）. The concentrations of cupric ion and indomethacin were analyzed by flame atomic absorption spectrometer （FAAS） for 60 days and UV/vis -3310 spectrophotometer for 60 days, respectively. The morphology of copper after corrosion was characterized by SEM. In addition, we detected cytotoxicity by MTT of L929 mouse fibroblasts cells caused by extracts of the three Yuangong Cu-IUDs. The release behavior of cupric ion for three kinds of Yuangong Cu-IUDs was biphasic, which consisted of the initial burst release and then slow and constant release. In vitro release experiment confirmed a biphasic release of indomethacin from Yuangong 220. The copper wire of Yuangong Cu-IUDs showed uneven corrosion. The RGR value of Yuangong 365 Cu-IUD was smaller than that of medicated Yuangong 220 Cu-IUD and RGR value of medicated Yuangong 220 Cu-IUD was smaller than that of Yuangong 300 Cu-IUD. The cupric ion release and indomethacin release showed biphasic. Indomethacin increased the cupric ion release rate and might diminish the adverse effects caused by burst release of cupric ion. The toxicity grade of these three Yuangong Cu-IUDs was 4. We should canvass the adverse events of Cu-lUDs based on practical experiments, and try our best to reduce the toxicity of Cu-lUDs.     

一种基于区分服务的IEEE 802.11 QoS信道访问控制机制

研究表明,无线移动自组织网络具有带宽有限,信道质量不稳定,节点移动造成网络拓扑结构变化等诸多特性,这些特性严重损害了网络性能,以致在传统无线移动网络中支持具有严格QoS要求的多媒体应用面临严峻的挑战.本文提出了一种基于区分服务的信道接入控制机制,以更好地支持实时通信流.该机制对传统的IEEE 802.11DCF机制进行...     

扇叶铁线蕨总黄酮和总酚含量及其抗氧化能力分析

测定了扇叶铁线蕨(Adiantum flabellulatum L.)的总黄酮和总酚含量及其对DPPH(DPPH˙)自由基、ABTS自由基(ABTS˙)的清除力和Fe的还原力.结果表明:1)扇叶铁线蕨总黄酮质量分数在6%~8%之间,总酚质量分数在7%~14%之间,地下部分总黄酮和总酚含量高于地上部分,不同产地的扇叶铁线蕨总黄酮和总酚含量存在一定差异;2)扇叶铁线蕨提取物具有一定的Fe还原能力,以及清除DPPH自由基和ABTS自由基的能力;且ABTS自由基清除能力和Fe还原能力随总黄酮和总酚浓度的增加而增强.     

变形温度、变形程度与退火方式对 TC11 钛合金显微组织的影响

文章采用金相跟踪法研究了变形温度、变形程度及随后的退火方式对ＴＣ１１钛合金显微组织的影响。     

牛顿法及带阻尼牛顿法的收敛域定理

本文给出了牛顿法和带阻尼牛顿法在满足|F′(x)-F′(y)‖≤K‖x-y}|~P,P∈(0,1)条件下的收敛域,并推广了[1—3]中的结果。