道床隔振垫的阻尼减振性能分析及应用研究

对道床隔振垫进行了在静态状态下锤击试验和在车辆正常运行条件下的轨道动态变形及振动测试,结果表明,道床隔振垫实际应用时的隔振频率在10—15 Hz之间。在静态条件下,相对于单趾弹簧扣件系统在20—200 Hz频率范围内,平均减振量为16.3 d B;在车辆运行条件下,隧道壁的垂向振动降低了17.3 d B。在静态和动态条件下,相对于单趾弹簧扣件系统,道床隔振垫减振效果基本一致。     

漏泄同轴电缆的性能参数及其影响因素的研究

本文介绍了漏泄同轴电缆的类型和漏泄原理,以双八字槽漏泄同轴电缆为例．分析和讨论了漏泄同轴电缆的主要性能参数及其影响因素．为漏泄同轴电缆的设计工作提供了参考依据。     

一种基于功率限制下的认知无线电的频谱感知模型

文中在功率限制规则下提出了一种模型,考虑到了路径衰减指数、角度准、发射功率对检测性能的影响,更具有实际性和精确性。本文主要在路径衰减指数α2〉α1时通过仿真合作增益方面分析了检测性能,同时考虑到角度准、发射功率对检测性能的影响。通过仿真可以看出,在α2〉α1的情况下很难得到较好的合作增益改善。从而得到基于合作中继的方法并不适用于IEEE802.22系统。     

开阔试验场的建造和测试

本文介绍新近建成的开阔试验场及其电气性能的测试。该开阔试验场用钢材建造，架高０９ｍ、长４０ｍ、宽１２５ｍ，其３ｍ法、１０ｍ法归一化场地衰减经测试，符合ＣＩＳＰＲＮｏ１６规范的要求。此外，还给出了２０ｍ法归一化场地衰减理论值和实测值，两者之间的偏差小于２６ｄＢ，并满足规范的场地可接受准则。该开阔试验场适用于建立３０～１０００ＭＨｚ高频电场标准和进行天线校准等电磁兼容试验。     

建立在相干检测原理上的单模光纤步级衰减标准装置

介绍了一种新的建立在相干检测原理上的光衰减标准。与采用功率比法的装置相比，本装置可以达到更高的灵敏度和更好的线性，其测试动态范围大于６０ｄＢ。     

Electroacoustic and Acoustic Attenuation Spectroscopy as New Tools for In Situ-Monitoring of Metal Oxide Precursor Preparation in Liquid Phase

The in situ-monitoring of a solid synthesis was realised by electroacoustic and acoustic attenuation spectroscopy. These techniques were applied to track the crystal growth of alumina precursor nanoparticles used as model compound. A commercially available set-up with a circular flow detector cell for joint electroacoustic and attenuation measurements was used. Course of zeta potential as well as particle growth was measured during continuous hydrolysis of dry Al-sec-butoxide in isopropanol. Zeta potential shows minima and maxima with increasing water amount, whereas particles start to grow significantly after a defined time of operation. In some experiments the synthesis was stopped ahead of time and the formed solids were additionally studied ex situ by characterisation methods such as solid-state NMR or transmission electron microscopy. Measured ultrasound data can be correlated to elemental processes during particle formation. First experiments on monitoring of synthesis scale-up show potential for future application of this technique.     

毫米波段衰减量测试方法研究

本文通过对多种传统衰减测试方法的比较，重点介绍了低频替代法在一种毫米波衰减自动测试系统中的应用，以满足迅速发展的毫米波技术对衰减参数检定的要求。     

Modelling of butene-1 dehydrogenation in a fixed bed reactor — bed and pellet profiles

A homogeneous model incorporating the Dumez & Froment kinetics has been proposed for the butene-1 dehydrogenation reaction over a commercial chromia-alumina catalyst. The model predicts bed and pellet concentration and temperature profiles. While the temperature profiles obtained suggest a temperature minimum in the reactor, the pellet remains nearly isothermal. Under the condition used in this study, a series type of coke deposition is obtained. A comparison between experimental results obtained using the neutron attenuation technique and theoretical coke profiles reveals excellent agreement and confirms the validity of the model and the kinetics employed.     

基于FFT的三维扫描图像深层损耗快速恢复方案

在分析三维共焦扫描图像衰减数学模型的基础上，针对其深层损耗进行了不依赖于试样的恢复。在确保恢复准确性的前提下推导出基于ＦＦＴ（快速傅里叶变换）的快速算法，该算法具有准确、高效、适应性强、不引入额外噪声等优点。讨论了算法的计算量、内存占用量及其在微机上的实现。提出相应的改善措施，并给出测试结果。     

Polymer Bonded Ferrite Materials as EMC Components

Polymer bonded ferrites composed of a mixture of Mn‐Zn ferrites or Ni‐Zn ferrites in a polymer binder (PE, PA) were prepared and tested as electromagnetic‐wave absorbing materials. Test samples and cases were prepared by hot or injection molding. Permeability spectra show loss contributions in the frequency range 100‐1000 MHz. Absorption measurements of injection molded polymer‐ferrite cases display a 3‐5 dB better attenuation characteristics compared to graphite‐loaded polyamide housings.