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961.
依据《建筑设计防火规范》的规定,结合条文说明,分析了动力总成车间、冲压车间、焊装车间、整车总装车间、涂装车间的火灾危险性分类。 相似文献
962.
A theoretical model in the 1900 nm waveband for amplified spontaneous emission (ASE) of thulium-doped silica fiber is presented. The ASE spectral power as functions of the fiber length and the pump power is investigated by solving the rate and propagation equations. By calculation, when the concentration of thulium in fiber is 2.25×1025 m-3, the fiber core diameter is 2.6 μm, and the pump power is 200 mW at 808 nm, the optimal fiber length is 8.1 m, and the output power of ASE can reach 60 mW in the range o... 相似文献
963.
在无线信道环境下,如何解决逻辑拓扑与物理拓扑之间的失配是设计P2P网络的主要挑战之一。本文提出一种适用于无线系统的P2P组网协议。在该协议中,首先,新入网节点从其邻居节点处获得一个数值上相近的节点标号,从而实现网络的瞬时拓扑感知。当节点的位置改变时,它们向中心节点更新自己的位置信息。然后,在中心节点处将节点标号的最优分配转换为旅行商问题,并用模拟退火算法对旅行商问题进行最优化求解,得到优化标号序列。最后,由中心节点向网络广播更新信息,引导节点进行标号和数据交换,从而使无线P2P网络在任何时刻都具有拓扑感知性。仿真结果表明,在基于该协议的无线P2P网络中,文件的定位路径明显缩短,定位延时明显减小。 相似文献
964.
965.
受阻胺光稳定剂和抗氧剂并用对聚合物紫外光稳定性的影响 总被引:1,自引:0,他引:1
阐述了受阻胺稳定剂(HALS)和抗氧剂的分类和作用机理,重点介绍了受阻胺类光稳定剂和抗氧剂并用对聚合物紫外光降解中的影响。当受阻胺类光稳定剂和抗氧剂并用时,既有协同效应,又有对抗效应,也有加和效应。这依赖于受阻胺类光稳定剂和抗氧剂的种类。同时介绍受阻胺光稳定剂发展的趋势。 相似文献
966.
薄片激光器均匀抽运及均匀冷却技术研究 总被引:4,自引:1,他引:3
均匀抽运及均匀冷却是激光二极管抽运激光器减小热致光学畸变以实现高光束质量输出的核心技术难题。通过开展键合薄片激光均匀抽运及均匀冷却技术的研究,采用透镜压缩结合波导匀化的设计思想,实现了95%以上的抽运均匀性。同时通过对薄片介质冷却通道的优化设计,实现了优于96%的温度分布均匀性。原理验证实验结果表明薄片介质的波前畸变得到了有效控制,当平均抽运功率密度为230 W/cm2时,忽略离焦效应后介质的反射波前畸变均方根值约为0.35μm。 相似文献
967.
TANG Xue-lin WANG Wu-chang WANG Fu-jun College of Water Conservancy Civil Engineering China Agricultural University Beijing China YU Xin College of Water Conservancy Civil Engineering China Yellow River Institute of Hydraulic Research Zhengzhou China CHEN Zhi-cong State Key Laboratory of Hydroscience Engineering Tsinghua University Beijing China SHI Xiao-yan College of Water Conservancy Civil Engineering China Agricultural Uni... 《水动力学研究与进展(B辑)》2010,22(2):196-206
A 2-D Lattice Boltzmann Method (LBM) coupled with a Sub-Grid Stress (SGS) model is proposed and validated by flows around a non-submerged spur dike in a channel. And then the LBM-SGS model is further applied to flows in a pumping-station forebay. Shallow water equations are numerically solved by the LBM and the turbulence can be taken into account and modeled efficiently by the Large Eddy Simulation (LES) model. The bounce-back scheme of the non-equilibrium part of the distribution function is used at the inlet boundary, the normal gradient of the distribution function is set as zero at the outlet boundary and the bounce-back scheme is applied to the solid wall to ensure non-slip boundary conditions. Firstly, the model successfully predicts the flow characteristics around a spur dike, such as circulating flow, velocity and water depth distributions. The results are verified by the experimental data and compared to the results obtained by conventional Smagoringsky Model (SM) of LES. Finally, the LBM-SGS model is used to further predict the flow characteristics in a forebay, such as secondary flow and water level. The comparisons show that the model scheme has the capacity to simulate complex flows in shallow water with reasonable accuracy and reliability. 相似文献
968.
DAI Wen-hong TANG Hong-wu State Key Laboratory of Hydrology-Water Resources Hydraulic Engineering College of Water Conservancy Hydropower Engineering Hohai University Nanjing China 《水动力学研究与进展(B辑)》2010,22(2):214-220
This article presents a mathematical model of the plane evolution of alluvial meandering streams,through downstream migration and lateral expansion of meander loops.Under the conditions prevailing in natural streams,the channel centerlines follow sine-generated curves,with an assumed steady-state turbulent and subcritical flow,of large width-to-depth ratio(≥ 15,for example) and small Froude number(Fr ).The plane deformation of the channel is caused by the action on the banks of the convective vertically-averaged meandering flow.The growth(migration and expansion) of meander loops is attributed to the regime-trend.The computational results of the model show that the obtained migration and expansion patterns of the meander loops are in good agreement with those of observations and measurements in similar meandering streams. 相似文献
969.
TANG Hong-wu XIN Xiao-kang DAI Wen-hong XIAO Yang State Key Laboratory of Hydrology-Water Resources Hydraulic Engineering Hohai University Nanjing China 《水动力学研究与进展(B辑)》2010,22(2):246-253
The simulation of a one-dimensional river network needs to solve the Saint-Venant equations, in which the variable parameters normally have a significant influence on the model accuracy. A Trial-and-Error approach is a most commonly adopted method of parameter calibration, however, this method is time-consuming and requires experience to select the appropriate values of parameter. Consequently, simulated results obtained via this method usually differ between practitioners. This article combines a hydrodynamic model with an intelligent model originated from the Genetic Algorithm (GA) technique, in order to provide an intelligent simulation method that can optimize the parameters automatically. Compared with current approaches, the method presented in this article is simpler, its dependence on field data is lower, and the model accuracy is higher. When the optimized parameters are taken into the hydrodynamic numerical model, a good agreement is attained between the simulated results and the field data. 相似文献
970.
JI Bin LUO Xian-wu State Key Laboratory of Hydroscience Engineering Tsinghua University Beijing China PENG Xiao-xing China Ship Scientific Research Center Wuxi China ZHANG Yao WU Yu-lin XU Hong-yuan State Key Laboratory of Hydroscience Engineering China 《水动力学研究与进展(B辑)》2010,22(6):753-759
Based on the Reynolds-Averaged Navier-Stokes equations and mass transfer model,an approach,where a three-component cavitation model is proposed,is presented to simulate ventilated cavitating flow as well as natural cavitation.In the proposed cavitation model,the initial content of nucleus in the local flow field is updated instantaneously,and is coupled with the Rayleigh-Plesset equation to capture the cavity development.The proposed model is applied to simulate the cavitating flow around an under-water veh... 相似文献