Experimental analysis of metal coated dielectric waveguides

This paper concerns the experimental characteristics of metal coated dielectric waveguides with a rectangular surface corrugation. Waveguide are designed to operate at a second Bragg frequency of 90 GHz. The period, height and the duty cycle of a rectangular grating were calculated using the chosen frequency. A metallic layer of aluminum is sputtered on one side of the slab waveguide. The purpose of the metallic layer is to simulate a layer of high density plasma on the surface of the waveguide similar to that obtained by optical excitation of semiconductor structures. Experiments were performed to examine the far field radiation pattern, attenuation constant and the dispersion relation. Due to the presence of the plasma layer there will be an angular shift in the far field radiation pattern. We have observed angular shifts of about 20 in the radiation pattern of the waveguide before and after coating. Measurements are made in the frequency range of 88–95 GHz. This waveguide structure can be used to design an electronically steerable antenna and an electronic phase shifter operating in the millimeter-wave frequency band.Supported in part by the Army Research Office.     

液态铅的电阻率

采用精确的结构因数实验数据和Ｂｅｈａｖｉ模型赝势，用Ｚｉｍａｎ理论计算了液态铅的电阻率．计算结果和实验数据符合很好．讨论了Ｚｉｍａｎ理论对液态铅的适用性以及适合于液态铅的赝势的特征．     

Pt-Pd /y-A120.催化剂氧化性能的研究‘

本文采用浸演法制备了一系列Pt-Pd/Y-AlzO,催化剂，并考察其对正己烷，正丁醉和苯的催化氧化性能.结果表明，Pt-Pd双组分催化剂对极性有机物正丁醉有很高的氧化活性，而对于非极性有机物苯和正己烷的氧化活性相对较差.对Y-AlzOa载体进行高温预处理后，催化剂对苯和正己烷的氧化活性有明显提高.     

全光亮镀铁工艺的研究

介绍了一种新型的电镀光亮镀的工艺,使用了“抑氢剂”,并用小槽电镀,Hull Cell实验研究了镀液的性能,还运用线性电位扫描法,旋转圆盘电极法测试了镀液的阴极极化性能和整平性能,采用SEM法观察镀层的形貌,实验结果表明：光亮剂的加入可增大铁沉积时的阴极极化,并伴有整作用,而抑氢剂可增大氢在铁上析出的过电位,从而可提高铁沉积的电流效率并降低镀层的应力。     

麻黄生物碱中一对光学异构体在薄层色谱原位的表面增强拉曼光谱研究

应用表面增强技术(SERS)将薄层色谱(TLC)与傅里叶变换拉曼光谱(FT-Raman)联用,在薄层色谱分离斑点原位,获得中草药麻黄中麻黄生物碱衍生物中一对关于手性碳的光学异构体：去甲基麻黄碱,去甲基伪麻黄碱指纹光谱的新方法。研究表明,在薄层色谱原位仅16 μg的样品,就可获得以上分子的主要特征谱带;并且光学异构体的光谱特征明显不同,在银溶胶微粒表面增强作用下去甲基麻黄碱、去甲基伪麻黄碱分子中与苯环相关的波数为1 004,1 605 cm-1振动获最大增强。从而阐明了应用TLC-SERS联用技术,可有效地对中草药主要化学成分中光学异构体进行高灵敏度分离与指纹鉴定。     

The preparation of nanophase tungsten carbide powder with zeolite-X catalysts

The reduction–carburization of tungsten trioxide (WO₃) under carbon monoxide flow was studied in the temperature range of 300–750 °C. The reduction–carburization of WO₃ was improved by mechanically mixing with zeolite-HX, -NaX and -KX. The interaction between cation in zeolite-X and oxygen in WO₃ affected the improvement of the reduction–carburization of WO₃ to WC. Moreover, the improved reduction–carburization of WO₃ could lead to the decrease of reaction temperature. Because the particle size of WC is in contact with a reaction temperature, the nanophase WC can be prepared at low temperature. In particular, the particle size of WC was controlled by reaction temperature. The particle sizes of produced WC at 550, 650 and 700 °C were 25, 50 and 100 nm respectively.     

PS_(3000)-b-PAA_(5000)球形胶束温度效应的原位小角X射线散射技术研究

应用小角X射线散射技术(SAXS)对两亲嵌段共聚物聚苯乙烯聚丙烯酸(PS-b-PAA)胶束形貌的温度影响进行了原位表征.SAXS结果表明:随着水含量的增加,粒子尺寸相应增加;对于水含量10%的PS_(3000)-b-PAA_(5000)胶束溶液,发现了明显的SAXS双峰现象;双峰的位置不随着温度的变化而改变,但是peak 1和peak 2的相对强度随着温度发生了减弱和增强的交错变化;相邻的SAXS双峰说明在PS_(3000)-b-PAA_(5000)胶束溶液中最初形成的粒子尺寸并不是均匀的,主要分为尺寸极其相近的两种球形粒子;随着温度的升高,粒径大小不同的两种粒子存在着一种消融和生长的过程,并且保持着一个相同的归一化动态平衡速率.     

定常吸气改善叶型气动性能的数值研究

提高叶型升力,扩大其稳定工作范围一直是叶轮机械领域关心的问题。本文针对采用定常吸气方法减缓低马赫数流动分离,改善叶型气动特性的问题,在NACA0015叶型上进行了多种工况的数值模拟。结果表明:在叶型头部吸力面分离点附近施加定常吸气,可以提高叶型升力,降低阻力,推迟失速2°左右。存在着最佳的定常吸气动量范围和吸气位置,使得其改善叶型性能的效果最大。文中还给出了定常吸气动量和施加位置等参数对叶型气动性能的一些影响规律。     

Misalignment tolerance analysis and fabrication for highly efficient parallel optical-electrical convertor module

A compact, highly efficient, and passively assembled parallel optical-electrical convertor module (POECM) for active optical cable application is proposed. This paper presents our POECM structure, optical design simulation results, fabrication process, and data transmission test results, in sequence. The POECM has a compact size of \(18.5\hbox {mm} \times 10\hbox {mm} \times 2.8\hbox {mm}\) . We confirm a data rate of total throughput at 21.6 Gbps ( \(5.4\hbox {Gbps} \times 4\) channels) with a bit error rate of less than \(10^{-12}\) .     

新时代背景下大学物理基础课程教学的讨论

本文讨论的是＂以怎样的理念实施大学物理基础课程教学,才能使学生的学习训练获得最大收益＂.文章首先回顾近30年来教学思想随时代发展的变化,然后提出新时代背景下大学物理基础课程教学＂以学生为中心,使广大学生在知识、能力、素质上获得全面提高＂的新理念.