杭州黄龙体育中心网球馆可开启屋盖的风洞试验

杭州黄龙体育中心网球馆屋盖属于可开启结构,部分屋盖可沿平行轨道滑动,结合该主体结构的抗风设计要求制作1∶100的刚性模型,进行了结构表面平均风压和脉动风压分布的风洞试验.分析了在不同风向角时关闭和开启屋盖状况下的风压分布.为了便于结构设计,根据实际情况对屋面进行分区并给出相应的分区风压数据,并依据各风向角下的风压分布特征,得出整体结构的抗风设计依据值.     

一种新的直序列长伪码捕获方案

针对长序列伪码捕获的特点要求,对传统的序列估计伪码捕获方法进行改进,提出了差分序列估计伪码捕获算法和FFT频率校正技术相结合的方法作为长伪码的捕获方案,对其工作原理进行了分析和理论推导.仿真结果表明,在高斯白噪声的情况下,该方法在捕获长序列伪码时的性能与传统的序列估计法相比较,在较低信噪比的情况下有较大提高,并能适应10 kHz范围的多普勒频移环境.     

ARP欺骗的原理及防范

在校园网维护过程中,我们经常遇到ARP病毒导致校园网的不稳定,影响了校园网的使用。本文介绍了ARP协议的工作过程以及ARP欺骗的原理,并给出了防范ARP欺骗的一些方法。     

MDF甲醛释放流变性的研究

在MDF甲醛释放蠕变过程中,MDF甲醛释放驱动力保持不变时,MDF甲醛释放量随时间延长而变化。马克斯韦模型可在甲醛释放驱动力为恒定条件下,较好地模拟MDF的甲醛释放流变性的规律;凯尔文模型较好地模拟了MDF甲醛延时释放特征;勃格模型是描述MDF甲醛释放蠕变的重要公式,它较好地模拟了MDF甲醛常规释放蠕变特征,换算得到的公式可较好地描述锯切后试件放置时间对MDF甲醛释放量的影响规律,是描述和预测MDF甲醛释放松弛特性的有价值模型;也可较好地描述干燥器测试时间对MDF甲醛释放量的影响规律,是描述和预测MDF甲醛释放蠕变特性的有价值模型。     

A two-stage algorithm of adaptive model-based parameter estimation and its application in the fast calculation of Green''s function in multi-layer soils

A two-stage algorithm is presented to determine an analytical model-based rational function by adaptively selecting sampling points. At the first stage, the rational interpolation function is created by using Stoer-Bulirsch algorithm and comparing the fitted model with the different ranks. At the second stage, the fitted model is validated by comparing with the first-principle model at a set of checking points. Some checking points will be added to the sampling series determined in the first stage to improve the fitted model. The new proposed algorithm is more accurate and effective than that using Stoer-Bulirsch interpolation only due to the fact that it appends the validation approach. When a highly oscillating curve is approximated, the validation ensures the fitting precision. With the two-stage MBPE algorithm, some time-consuming electromagnetic computations can be replaced by the interpolation from the fitting functions, which can increase the computational efficiency greatly. This method is used to calculate the samplings of the Green's functions in a multi-layer horizontal soil to demonstrate its effectiveness. The number of samples used to accurately model such Green's functions is less than 20 for the typical soil parameters. The computational time can be reduced by more than two orders of magnitude compared with that using the conventional uniform sampling technology.     

《微机原理及应用》CAI课件的设计

CAI多媒体教学已广泛应用于高校的教学之中，成为现代化教学的一种手段，但由于专业的差别，专业基础课的CAI课件作品比较少，不利于CAI教学的开展。根据多年来《微机多年来《微机原理及应用》课程的教学经验，利用Authorware、Photoshop、Cool3D等开发工具，制作了本课件，并逐步用于教学中，收到了很好的教学效果。     

己二酸十八酯(OAO)晶体谱学研究

测定了OAO粉末衍射、红外光谱和几何配置为y(zx)y、y(zz)y和 y(xz) y、 y(xx) y的拉曼光谱 .实验结果表明 ,OAO晶体最强衍射 2d =9.0 716nm ,拉曼光谱中烷烃链的几个振动模式出现偏振 ,由此可推测其晶体结构是沿 [10 0 ]和 [0 0 1]方向排列成层 ,分子层间沿 [0 10 ]方向堆垛     

汽车道路模拟试验台计算机测控系统的开发

计算机测控系统是汽车道路模拟试验台的关键部分。在研制国产化的汽车道路模拟系统过程中 ,开发了专用的计算机测控系统。分析了道路模拟试验对测控系统的特殊要求 ,构成测控系统时只采用了通用的廉价硬件插卡模块 ,而系统要求的大容量不间断采样与输出、数据输入和输出同步等特殊功能 ,采用复杂的编程用软件方法实现。这种方案构成的系统具有很高的性能价格比 ,从而为降低所研制的道路模拟系统的成本打下了很好的基础。实验证明 ,所开发的测控系统配置合理且能达到很高的精度。     

基于水声矢量传感器阵的波达方向估计

推导了基于水声矢量传感器阵的Bartlett和Capon空间谱的解析表达式，并与标量传感器的空间谱相比较，分析了基于矢量传感器阵的两种DOA估计方法对阵列定向性能的改善，并给出了数字算例。     

Adjustable character of microwave attenuation in BaTiO3 electrorheological fluids

The behavior of microwave attenuation in BaTiO3 electrorheological fluids is studied when considering microwave propagation in the directions perpendicular and parallel to the particle chains, respectively. In the former case, the microwave attenuation increases with field strength when the particle concentration is low, and the increase of the particle concentration can also increase the microwave attenuation. However, when the particle concentration exceeds a critical value, the attenuation will first increase then decrease with field strength. At the same time, the higher the field strength, the greater the change of microwave attenuation. Moreover, there is a saturation field strength. When the field strength is lower than the saturated one, the change of microwave attenuation is fast. On the other hand, in the case of microwave propagation parallel to the particle chains, the microwave attenuation increases with the field strength monotonously. In addition, the variation of microwave attenuation with the field strength shows relaxation effect. The adjustable character of microwave attenuation in BaTiO3 ER fluids can be attributed to the dielectric changes resulting from the field-induced-structural transformation and the polarization of BaTiO3.