Possible Collapse Mode for Slender Reinforced Concrete Plates Subjected to Blast Load     

ZHANG Xin  DU Xiuli  CHEN Zhen  ZENG Fanna 《天津大学学报(英文版)》2008,(Z1)

This paper discusses the collapse mode of thin reinforced concrete (RC) plates sub-jected to blast load. To extend the well known plastic-mode method to analyze, not only perfect-plastic plates , but also RC plates, it is needed to investigate the effect of material cracking on the collapse mode because the plate might have been cracked on both upper and lower surface before the plastic-mode fully develops, creating an unexpected type of collapse mode shape. A new fail-ure mode is proposed and verified by numerical analysis in this paper. The new mode is a result of the material cracking and has an un-negligible effect on the reaction mechanism of the RC plate to the blast load.  相似文献   

基于FPGA的实时SAR成像系统的设计与实现     

程雪红  谢佳 《西安文理学院学报》2008,11(2):89-92

根据合成孔径雷达（SAR）成像基本原理,结合当前基于现场可编程门阵列（FPGA）实现数字信号处理的能力,本文对SAR成像系统的FPGA实现方法做了深入探究.该系统设计将SAR成像算法映射到FPGA中进行实现,结合重新时序分布、展开与合并等算法实现技术,同时注重流水线、并行处理等基本设计技巧,极大地提高了SAR成像系统的运算精度和运算速度.通过仿真验证,设计的系统具有实时高性能的特点,可以很好地满足空载实时SAR成像要求.  相似文献   

青少年田径运动员晨脉变化与心功能、尿常规、血红蛋白的关系研究     

韦军 《西安文理学院学报》2008,11(3):123-125

在青少年田径训练过程中,由于运动负荷掌控出现问题,造成运动损伤、营养不良、内分泌紊乱等现象,严重影响了高水平体育后备人才的培养．因此,如何用最简便的方法对青少年运动员进行训练监控,成为基层教练员亟待解决的问题．文中对青少年田径运动员进行晨脉、心功能、尿常规、血红蛋白的同步追踪测试,确定了不同晨脉所对应的心功能、尿常规、血红蛋白的参数变化,从理论上进一步确定晨脉监控在运动训练中的作用,为青少年田径训练工作提供科学依据．  相似文献   

稀土、碱金属在特定催化反应中的调变机制     

蔡炳新 《怀化学院学报》1991,(2)

本文研究了稀土,碱金属添加物分咽在以氢型丝光沸石(HM)为载体的pt—v_2o_5催化剂、碱土金属氧化物(Cao)催化剂中对抑制积炭,促进甲烷氧化偶联反应的作用机理。发现:稀土以碱性,强供氧能力抑制酸中心和金属中心的积炭;碱金属以强供电子的能力诱导偶联催化剂活性组分o的生成而导致活性,选择性的提高.  相似文献   

Magnetic Properties of Nanocrystalline Fe60Cr40 Powders Prepared by Mechanical Alloying in Vacuum and Air     

沈刚  马学鸣 《上海大学学报(英文版)》2005,9(1):86-89

Magnetic properties of nanocrystalline Fe60 Cr40 powders prepared by mechanical alloying in vacuum and air were investigated by utilizing the measurements of magnetization, X-ray diffraction, and ^67Fe M（oe）ssbauer spectrum. The results show that the Fe60 Cr40 powders keep the bcc structure during milling in air and vacuum. The saturation magnetization of the Fe60 Cr40 powders milled in vacuum and air decreases with the increase of the milling time up to 45 h. The decrease of saturation magnetization of the Fe60Cr40 powders milled in vacuum is due to the formation of Fe-Cr solid solution, while in air it is due to the formation of paramagnetic disorder structure and solid solution.  相似文献   

圆柱导体对强电磁脉冲的散射特性研究     

李应乐  王明军  王西明 《咸阳师范学院学报》2006,21(6):12-14

利用数字信号处理技术和电磁场理论,研究了圆柱形导体目标对强电磁脉冲波的散射及目标表面上感应电流;仿真了目标对脉冲散射的同极化衰减随时间的变化以及目标上的脉冲电流的时间变化规律。这不仅适用于研究导体目标的脉冲散射特性,而且适用于形状复杂目标的脉冲散射特性研究介质中的脉冲衰减研究,具有算法简便、准确、高效等特点。  相似文献   

面向动态交通分配的城市道路网络分区研究     

李润梅  宫晓燕 《中国科学院研究生院学报》2006,23(4):520-526

本文提出了城市道路网络的动态可分配性概念，以衡量对特定城市道路网络实施动态分配研究的有效性。并将这个概念用于面向动态交通分配的城市道路网络子区划分，考虑了道路网络的动态变化特性，不仅在空间上，也在时间上对道路网络进行了分区研究。该研究可为动态交通分配的建模研究提供合理的背景和对象。  相似文献   

Free radical injury and antioxidant status in patients with benign prostate hyperplasia and prostate cancer     

D. S. L. Srivastava  R. D. Mittal 《Indian journal of clinical biochemistry : IJCB》2005,20(2):162-165

Reactive oxygen species and other free radicals are known to be the mediators of phenotypic and genotypic changes that lead from mutation to neoplasia. There are some primary antioxidants such as glutathione peroxidase (GPx), glutathione S-transferases (GSTs) and reduced glutathione, which protect against callular and molecular damage caused by the reactive oxygen metabolites (ROMs). The present study was conducted to determine the level of malondialdehyde (MDA), as an index of lipid peroxidation, along with the GPx, GSTs activities and level of reduced glutathione in 45 prostate cancer (PC) patients, 55 benign prostate hyperplasia (BPH) patients as compared to the controls. Significant higher levels of MDA and GSTs activities in the serum, (P<0.005) and significant lower levels of reduced GSH concentration and GPx activity in blood haemolysates (P<0.05) of PC and BPH patients were observed as compared to the controls. The relatively higher GSTs activity and low level of reduced GSH may be due to the response of increased reactive oxygen metabolites production in the blood. The higher MDA and lower GPx activities may be inadequate to detoxify high levels of H₂O₂ into H₂O leading to the formation of the^*OH radical followed by MDA. This result hypothesizes that oxidant-antioxidant imbalance may be one of the major factor responsible for the development of prostate cancer and benign prostate hyperplasia.  相似文献   

步进电机的软件脉冲分配     

王玉琳 《中国科技信息》2005,(18):7

本文介绍了一种步进电机软件脉冲分配的方法。按照要求的脉冲分配顺序将步进电机的绕组通电节拍制成表格,软件采用查表的方式取出通电节拍输出到功放电路。采用软件环分,降低了硬件成本,提高了驱动电源的可靠性,方便于实现变拍驱动。文章还提出了步进电机绕组通电状态保存和恢复的方法,解决了驱动电源上电后电机转轴发生偏移的问题,提高了步进电机的定位精度。  相似文献   

脉冲模拟调制的分析     

夏云波 《齐齐哈尔师范高等专科学校学报》2008,(6):123-125

脉冲调制是用采样信号的采样值去控制脉冲序列信号的参数。脉冲序列信号有4个参数：脉冲幅度、脉冲宽度、脉冲位置、脉冲频率。因此脉冲模拟调制有4种方式：脉冲幅度调制（PAM）、脉冲宽度调制（PWM）、脉冲频率调制（PFM）、脉冲位置调制（PPM）。这几种调制方式的信号产生和解调原理与实现方法有很多相似之处,本文就PPM信号的产生与解调方法进行分析。  相似文献