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991.
从热管的吸液芯对传热性能的影响出发,分别对以铜材泡沫金属和丝网为吸液芯的热管进行了传热性能试验研究,两种热管的工质都为质量浓度为1%的Al2 O3纳米流体。试验结果显示泡沫金属吸液芯热管在等温性、换热系数和传热极限等方面都要比丝网吸液芯热管更好,泡沫金属吸液芯热管的传热性能要优于丝网吸液芯热管。 相似文献
992.
LIU Yu-jun ZHU Xiu-li JI Zhuo-shang 《船舶与海洋工程学报》2005,4(3):13-17
The problem of ship hull plate processing surface fairing with constraints based on B-spline is solved in this paper. The algorithm for B-spline curve fairing with constraints is one of the most common methods in plane curve fairing. The algorithm can be applied to global and local curve fairing. It can constrain the perturbation range of the control points and the shape variation of the curve, and get a better fairing result in plane curves. In this paper, a new fairing algorithm with constraints for curves and surfaces in space is presented. Then this method is applied to the experiments of ship hull plate processing surface. Finally numerical results are obtained to show the efficiency of this method. 相似文献
993.
川芎嗪对大鼠局灶性脑缺血损伤的神经保护作用 总被引:1,自引:0,他引:1
目的观察川芎嗪对局灶性脑缺血后脑损伤的保护作用。方法采用线栓法制作大鼠左侧大脑中动脉阻塞模型。氯化三苯基四氮唑(TTC)脑片染色测定脑梗死体积,干湿重法测定脑组织含水量,快速Golgi银染方法观察脑缺血周围区神经元的形态改变。结果川芎嗪能明显缩小脑梗死体积、降低脑组织含水量,随着川芎嗪剂量增大,作用更为明显,具有剂量依赖性。脑缺血后14 d Golgi银染显示,模型组在梗死周围区神经元明显减少,变性和正常神经元共存。变性神经元主要表现为突起断裂、增粗,突起有大的串珠,树突棘减少。川芎嗪组较模型组皮质梗死周围神经元变性较少。结论川芎嗪能缩小脑梗死体积、减轻脑水肿、保护缺血周围神经元,证实川芎嗪对脑缺血损伤有保护作用。 相似文献
994.
This paper introduces a new means to predict consolidation deformation of soil from its microstructure. Based on a kind of
pore-size distribution density function, a fractal model for soil consolidation is established. Through this model, the relation
between macroscopic deformation and microcosmic pore property of soil is founded. In order to justify this proposed model
for soil consolidation, consolidation experiments of soft clay are performed. Afterward, the microstructure of soft clay unconsolidated
and consolidated under every pressure is studied by a scanning electron microscope (SEM). The results show that the proposed
model for soil consolidation is valid in predicting consolidation deformation. 相似文献
995.
The non-destructive testing (NDT) of debonding in stainless steel composites plate (SSCP) is performed by infrared thermography,
finite element analysis (FEA) software ANSYS is taken as the simulative tool, and 2D simulative model has been set up to investigate
effect of the thickness of coating and/or substrate on the detectibility of debonging in SSCPs. Two parameters, namely the
maximum defect temperature difference and defect appearing index, are defined to evaluate the detectivity of defects, and
their computational methods and formulas are given respectively. The preliminary changing tendency of the maximum defect temperature
difference and defect appearing index with the thickness of coating and/or substrate is found by numerical simulation. 相似文献
996.
本文介绍一种PDA交通管理系统。采用具有高速处理器芯片PXA255的PDA对违章车辆的车牌号码、颜色和车型、违章车辆速度扣闯红灯时间等数据进行提取和识别,然后通过GPRS通信,送给无线接入装置。无线接入装置把这些数据传给Internet,Internet再把这些数据传给交通管理系统数据中心。PDA采用嵌入式Linux操作系统,能根据需要修改内核。 相似文献
997.
拱桥吊杆体系内部钢丝是日常检查和养护盲区。结合吊杆体系检测的步骤,分析吊杆各部分的渗水通道,探索有效检查方法,分析钢丝损伤的原因,并提出吊杆体系各部位的防护措施,为类似工程提供参考。 相似文献
998.
999.
Philip J. Zwart Philippe G. Godin Justin Penrose Shin Hyung Rhee 《Journal of Marine Science and Technology》2008,13(4):346-355
An accurate, efficient algorithm for solving free surface flows around ship hulls is described. Accuracy is achieved using
a compressive advection discretization which maintains a sharp free surface interface representation without relying on a
small time step. Efficiency is obtained using a solution algorithm which implicitly couples velocity, pressure, and volume
fractions. The algorithm has been implemented in a computational fluid dynamics code called CFX and is validated by means
of a comparisonwith experimental data of benchmark cases in both steady and transient conditions. 相似文献
1000.
当前我国城市青少年的消费观念和消费结构都在悄悄地发生着转变.本文在市场调查的基础上,阐述我国城市青少年消费心理和消费行为特征,详尽地分析了影响青少年消费的各种因素. 相似文献