自动源调配器测量晶体管噪声参数的补偿计算

在微波噪声参数测量系统中,通过使用自动源调配器来改变源反射系数的方法,可以方便地求出各个参数。根据对所引入的自动源调配器的分析,总结出源调配器自身的额外噪声误差是可以忽略的,并在对自动源调配器与噪声源级联后组成的单端口网络进行误差分析后,做出了超噪比的补偿运算,这种误差修正方法在很大程度上减小了测量误差量级。使用该补偿方法可以在噪声参数测量时进行更大范围的源阻抗调配,并提高噪声测量的准确度。     

河南省社会主义新农村住宅示范图电气设计

由于目前农村TT、TN两种供电系统并存,河南省社会主义新农村住宅示范图电气设计,总结出一张图纸两种供电系统兼用的表示方法。两种系统接地之别在户外电度表箱处区别处理,出线后则完全相同,均设两级剩余电流保护装置、实施总等电位联结。电气、防雷,户内绝缘隔离、户外联合分户一点接地,既等电位又避免户与户间故障电压相互传递。     

鄂尔多斯盆地西缘南北向断裂的发育及其地质意义

该文对鄂尔多斯盆地西缘断裂带中最重要的一条断裂,即青铜峡—固原断裂的几何学、运动学和动力学特征进行了综合研究,认为该断裂带上出露的辉绿岩属于"构造冷侵位"。断裂带两侧在石炭—二叠纪之前有各自不同的地质发展史,三叠纪后断裂带两侧沉积环境基本一致,说明了该断裂为不同地体的碰撞拼贴带。青铜峡—固原断裂带对其西侧的祁连造山带和东侧的鄂尔多斯盆地中央古隆起的形成均起着重要的控制作用。     

Growth of SiC nanowires and nanocones using mixture of oil palm fibres and rice husk ash

3C-SiC nanowires and nanocones were grown by pyrolysing mixture of acid-treated oil palm empty fruit bunch fibres and rice husk ash (RHA), which acted as carbon and silicon source, respectively. The effects of different RHA amounts and pyrolysis temperature were studied. When the amount of RHA was increased to 80 % of the mixture, there was a change in the morphology from nanowires to nanocones. Overall, it was found that 40 % of RHA in the mixture was the ideal amount in growing the nanowires with the maximum yield and with the least amount of impurities. When the pyrolysis temperature was raised, there was an increase in the amount, diameter and length of the nanowires. The proposed main growth mechanism for the SiC nanowires were combination of solid-state reaction and vapour–solid mechanisms, with some nanowires grown under vapour–liquid–solid (VLS) mechanism induced by trace metals as well. The growth of the nanocones could also be related to VLS mechanism.     

A novel silver–aluminium high-temperature die attach nanopaste system: the effects of organic additives content on post-sintered attributes

An Ag–Al die attach material having a fixed Ag–Al nanoparticles weight percent content (80–20 %), as well as varying organic additives weight percent content was formulated. The total nanoparticle weight percent content was varied between 84.7 and 87.0 %. As the organic additives content in the Ag₈₀–Al₂₀ die attach material decreased from 15.3 to 13.0 %, the nanopaste’s viscosity increased. The die attach material was sintered at 380 °C for 30 min to form Ag₂Al and Ag₃Al compounds. With decreasing organics content from 15.3 to 13.0 %, the porosity of the post-sintered samples also decreased from 30 to 19 %, while the density increased from 2.36 to 6.42 g/cm³. The highest melting point was recorded for the sample with the least organic weight percent content at 519 °C. The coefficient of thermal expansion and electrical conductivity values varied between 6.99–7.74 × 10^?6/ °C and 0.95–1.01 × 10⁵ (ohm-cm)^?1 respectively with decreasing organic content from 15.3 to 13.0 %. The electrical conductivity values recorded were higher than or equal to that of most solder alloy die attach materials. By changing the organic additives content in the Ag₈₀–Al₂₀ die attach material, suitable properties are obtained for high temperature die attach applications.     

循环流化床锅炉风机变频节能改造

本文介绍了高压变频器在寿光金太阳热电厂75t/h循环流化床锅炉的应用情况,应用实例表明,使用高压变频系统,改善了设备的运行工况,用户节能效果明显。     

深基坑监测锚索应力异常情况分析

深基坑支护工程中,常采用桩锚结构支护.对锚索穿过细砂层的桩锚支护结构中的锚索应力异常情况结合其他监测项目进行分析,采取相应工程措施后,通过监测锚索应力变化情况来判断采取措施的效果,对穿过细砂层的锚索应力异常情况分析及处理具有参考意义.     

基于风洞试验的苏通大跨越输电塔风振系数研究

苏通大跨越输电塔的结构形式有别于普通的钢结构杆塔,其塔身下部结构采用钢管混凝土、上部结构采用钢管,质量突变大,主要受风荷载控制,并且塔高超出GB 50009—2012《建筑结构荷载规范》的梯度风高度限制。为此,采用气动弹性模型和刚性模型的边界层风洞试验确定苏通大跨越输电塔的风致响应和气动力,基于试验数据计算不同风向角下的惯性力风振系数、位移风振系数和有效荷载风振系数,并进行对比。并通过有限元分析梯度风高度对惯性力风振系数的影响,同时将有限元分析得到的风振系数分布和加权值与DL/T 5154的风振系数规定作比较。结果表明：上述3种风振系数分布规律并不相同,由其分别确定的等效位移接近于试验值;考虑梯度风高度后,风振系数变小,分布形状影响小;苏通大跨越输电塔的惯性力风振系数加权值小于1.6,且风振系数由下到上不是单调增大。     

氯化熔盐体系黏度特性研究现状

中国钛原料钙镁含量高,主要采用熔盐氯化法处理,会产生大量废盐难以处理。研究氯化熔盐体系的黏度特性对于开发该工艺产生的大量废盐利用新方法具有重要意义。综述了国内外对氯化熔盐体系黏度影响规律的研究：从氯化熔盐体系的熔盐离子出发,探讨了Ca²⁺、Mg²⁺、Na⁺及K⁺等对氯化熔盐黏度的影响;从反应条件出发,探讨了温度、气氛和添加剂对氯化熔盐黏度的影响。结合当前对氯化熔盐体系黏度的研究,针对NaCl-KCl-CaCl₂-MgCl₂四元氯化熔盐体系,在不同温度条件下改变气氛或者添加剂,对体系黏度的变化规律进行了考察。通过改变氯化熔盐体系的黏度,寻求适合高温相转化渣高效分离的手段和方法,对高温相转化法高效循环处理熔盐氯化废渣具有重要意义,并能有效推动中国熔盐氯化法的发展。