摘要：In accordance with the enhancement for luminous efficiency improving, LED (Light Emitting Diode) has been gradually developed by combining the characteristics of small volume, impact resistance, good reliability, long life, low power consumption with multiple purposes for energy saving and environmental protection. Therefore, the array LED has been widely applied in human livings nowadays. This study applies the finite element analysis software ANSYS to analyze the thermal behavior of the array power LED work lamp which is modeled by four same-size LED with MCPCB (Metal Core Print Circuit Board) mounted on a base heat-sink. The Flotran heat flow analysis is applied to obtain the natural convection of air coefficient, while the convection value can be confirmed by the iterative method since it is set as the boundary condition for ANSYS thermal analysis to obtain the temperature distribution, accordingly the chip junction temperature and the base heat-sink temperature were followed through experiments in order to check if the simulation results meet the design requirements and coincide with the power LED product design specification. Prior to the optimal design process for chip junction temperature, the most significant parameters were first chosen by the fractional factorial design. The regressive models were respectively setup by the dual response surface method (RSM) and the mixed response surface method. Furthermore, the genetic algorithm combined with response surface method was applied to acquire the optimal design parameters, and the results were obtained from both methods, which are reviewed for comparison. Afterwards, the mixed response surface method is adopted to investigate the effects of interactions among various factors on chip junction temperature. In conclusion, it is found that the thermal conductivity of MCPCB and the height of base heat-sink are the two major significant factors. In addition, the interactive effects between chip size and thermal co

摘要：基于贝茨理论,结合具体工程实际,对某中型风力机叶片进行外形设计。并在此基础上提出了风力机叶片的三维建模方法,即利用点的坐标变换理论来计算叶片各断面翼型的空间实际坐标,然后运用UG强大的三维曲面建模功能来建立叶片复杂曲面。该文提出的方法减少了风力机叶片等复杂曲面的建模工作量;叶片实体模型的建立也为叶片的气动性能计算和结构设计与分析奠定了基础。

摘要：为评定排水性沥青路面混合料的透水能力,设计了不脱模大马歇尔试件竖向渗透系数和水槽横向渗透系数测定方法,并制作了测试装置,对不同成型方法、不同空隙率的PAC-13与PAC-16试件进行了控制水头差的渗透系数测定.测试结果表明:排水性沥青混合料的渗透系数与空隙率有着良好的相关性,击实成型试件的渗透系数略大于静压成型试件,PAC-16的渗透性能优于相同空隙率的PAC-13且变化规律一致,试验测定的竖向渗透系数与横向渗透系数在工程常用的空隙率情况下相对误差不超过20%,有较好的一致性.工程设计应用中,采用与路面材料状况较一致的击实成型的不脱模大马歇尔试件测定竖向渗透系数能较好地反映排水性沥青混合料的渗透性能.

摘要：为向路面结构设计和沥青混合料抗剪设计提供参考,用室内环道试验数据建立了基于抗剪性能的车辙预估模型,并与现有车辙预估模型进行了比较.为了标定该车辙预估模型,采用2条高速公路沥青路面现场实测数据,对车辙预估值和实测值进行了比较.结果表明:与现有车辙预估模型相比,除综合系数有差别外,其余参数值相差较小;当修正系数为0.361 3时,预估值和实测值吻合较好.

摘要：全面介绍了６种不同成分土和碎石混合料的蠕变试验，包括试件的准备、数据的采集以及成果的整理方法。运用回归搜索迭代方法所得的蠕变规律为考虑材料粘弹性的高填方工后沉降计算提供了各项参数。

摘要：针对检重秤测量过程中受振动干扰影响严重的问题,提出一种基于外部输入非线性自回归模型(NARX)的动态神经网络系统辨识的抗振新方法。通过加速度传感器的冗余分布,对检重秤系统的振动特性进行估计,结合空载传送情况下称重传感器由振动干扰产生的误差,利用动态神经网络对振动干扰信号进行自动辨识,建立振动信号分析模型,用以匹配消除动态检重信号中的振动扰动。在共振状态下,与滑窗滤波、自适应陷波等传统抗振方法进行的仿真与测试实验对比,证明基于多加速度传感器的动态称重抗振性能更优,最终实现运行速度达2 m/s,最大秤量200.0 g,满足国家标准《GB/T 27739-2011自动分检衡器》XIII级要求的检重秤搭建。

摘要：为解决水轮发电机组在优化设计中出现的技术矛盾,改善机组的各项性能,在对某混流式水轮发电机组进行优化设计时,为解决机组堵塞严重的问题,同时让机组在优化设计前后流场、效率以及出力等参数基本保持在设计值,提出了减少叶片数量的方案,分析了减少叶片数量会导致恶化的参数类型,以TRIZ发明原理的推荐方案为指导原则构建技术矛盾关系,并提出了降低活动导叶高度和增大叶片表面积等优化措施,对全流道进行CFD数值计算和现场实测两个方面验证改造效果。结果显示,改造后机组的流态良好,堵塞频率显著下降,且效率和出力均达到了预期水平,为后续机组的进一步优化设计提供了参考依据。

摘要：为优化水轮发电机组的出力性能,节约施工成本,提出了设计椭圆形截面蜗壳的思路。以一台混流式水轮机组的蜗壳为研究对象,建立了额定工况下圆形及1.1∶1.0、1.2∶1.0长短轴比的椭圆截面设计方案的计算模型,设置相同的条件进行CFD流场分析,优选出了流动性能合理的设计方案。模型试验结果显示,各测点的速度和压力仿真与试验数据相比较平均误差较小,蜗壳的试验效率基本满足要求。采用椭圆形状的蜗壳,有利于改善机组的出力性能。

摘要：A new physical current-voltage model for polysilicon thin-film transistors （poly-Si TFTs） is presented. Taking the V-shaped exponential distribution of trap states density into consideration,explicit calculation of surface potential is derived using the Lambert W function, which greatly improves computational efficiency and is critical in circuit simulation. Based on the exponential density of trap states and the calculated surface potential, the drain current characteristics of the subthreshold and the strong inversion region are predicted. A complete and unique drain current expression, including kink effect, is deduced. The model and the experimental data agree well over a wide range of channel lengths and operational regions.

摘要：目的：介绍髂腰血管蒂髂骨（膜）瓣的应用解剖和临床应用。方法：选用２７具５４侧灌注红色乳胶的成人标本，对髂腰血管的起始、走行、分支、变异及有关毗邻进行观测，对血管外径、长度及末端分布进行测量。手术设计沿髂嵴内缘入路，于髂肌浅层显露达腰大肌外缘，切取血管蒂骨瓣移植。临床应用２例。结果：髂腰血管走行恒定，蒂长７．０±３．９ｃｍ，腰大肌外缘处外径２．０±０．４ｍｍ，分布在髂嵴中段范围７．０±２．２ｃｍ。临床应用效果良好。结论：本文为带血供髂骨（膜）瓣移植提供了一种可行的新术式。