A novel method for the measurement of frequency-character of surface resistance of HTS thin film

A novel method for microwave surface resistance measurement of high temperature superconductor thin film at multi-frequency by multimode of sapphire rod is introduced. This method has the advantages of high sensitivity and large dynamic range of the measurement. By using this method, the frequency dependent microwave surface resistance of a single piece of high temperature superconductor thin film can be characterized within one temperature cycle. This method is capable of reducing the amount of work in sur...     

2-乙基苯并噁唑的微波超声波辅助合成

以2-氨基苯酚、丙酸为原料,多聚磷酸为催化剂,微波超声波辅助合成了2-乙基苯并噁唑.通过考察原料与催化剂摩尔配比,反应温度,反应时间等因素的影响,得出较佳工艺条件为:微波和超声波功率分别为800 W,2-氨基苯酚与丙酸的摩尔配比为1:5.5,催化剂多聚磷酸与2-氨基苯酚的摩尔配比为0.52:1,130℃,反应时间15 min.反应液经萃取、减压蒸馏处理,得含量为99.78%的产物,产率47.96%,产物结构通过质谱、红外光谱和核磁共振进行了确认.产物具有浓郁的青香、咸香、清甜、凉香气特征,与2-甲基苯并噁唑相比,香气差别较大.     

微波法合成低分子量聚L-乳酸研究

在微波辐射条件下，以L-乳酸为原料抽真空直接合成低分子量聚乳酸。根据微波辐射的特点制作了两口长颈反应釜，考察单体纯度、催化剂种类和用量、聚合时间、聚合温度等因素对聚卜乳酸粘均分子量的影响，确定了最佳工艺；并采用IR、^1HNMR和^13CNMR等测试手段对聚合产物进行了结构表征。     

茶叶中咖啡因的提取和分析

采用微波法,以95%乙醇为溶剂,NaAc为沉淀剂代替传统的石灰石,将萃取、升华、重结晶等方法结合在一起来提取、纯化茶叶中的咖啡碱。结果表明,产物经红外光谱鉴定分析为咖啡因,测出在茶叶中咖啡因含量为3.25%。说明微波技术辅助提取是值得推广普及的绿色萃取新方法,可以弥补有机溶剂提取成本高与时间长的不足,提高咖啡因产率。     

波导宽边缝隙辐射特性的研究

本文应用伽略金法研究矩形波导宽边上斜缝隙的辐射特性。根据等效原理和并矢格林函数理论建立了积分方程组,用矩量法将积分方程化为矩阵方程,借助计算机求解数值。这种处理方法近似条件少,所得数值解的精度高,可用于波导宽边上多个辐射缝隙的波导缝隙天线系统和波导窄边斜辐射缝隙的分析中。     

Blind estimation of phase offset in OFDM subcarrier for coherent demodulation

An adaptive algorithm named low complexity phase offset estimation (LC-POE) is proposed for orthogonal frequency division multiplexing (OFDM) signals. Depending on the requirement, the estimation procedure is divided into several scales to accelerate the adaptive convergence speed and ensure the estimation accuracy. The true phase offset is estimated through shrinking the detection range and raising the resolution scale step by step. Both the convergence performance and complexity are discussed in the paper. Simulation results show the effectiveness of the proposed algorithm. The LC-POE algorithm is promising in the application of OFDM systems.     

Preliminary analysis of chemical reaction under the radiation of electromagnetic wave

Microwave can be used to accelerate chemical reaction and improve the rate of production. Does microwave only act as a heating factor? Do there exist any specific effects? These questions are still holding a violent controversy. Here we will choose the Belousov-Zhabotinsky reaction, which is sensitive to surrounding effects, to study the influence of microwave on chemical reactions. Visible changes of periods have been observed. It appeares that there could have been specific effects of microwave.     

微波炉在公路工程中的应用

分析酒精燃烧法和烘干法在公路工程中的缺点,结合酒精、微波炉与烘箱的对比试验,分析微波炉在工程中的应用。     

微波常压法合成正丁醚

采用微波常压法，利用正丁醇在浓硫酸作用下的脱水反应合成了正丁醚。反应时间只需20min，反应速度至少是常规反应的6倍。     

电磁场理论中几何化·数论消发散方法(Ⅱ)——简约电荷分布、一般形式解及数论消发散定理

该文为GNES方法论文系列中的第二篇.建议简约电荷分布的概念,并讨论其应用.给出一般的基本积分方程组的形式解,它将由几何参数直接表示电容系数.给出数论消发散定理,它提供了既自然地消除积分核的对角线奇性,又能同时运用数论方法的一个具体方案,而且不带调节参数.