Modeling of current-voltage characteristics for strained andlattice matched HEMT's on InP substrate using a variational chargecontrol model

A model for the calculation of the current-voltage characteristics of strained In_0.52Al_0.48As/In_xGa_1-xAs on InP substrate High Electron Mobility Transistors (HEMT's), based on a variational charge control model, is presented. A polynomial fit of the two-dimensional electron gas (2DEG) density is used for the calculation of the current-voltage characteristics. The effect of strain is introduced into the 2DEG density versus gate voltage relation. Very good agreement between the calculated and measured I-V characteristics was obtained. In addition, our results show that, for an indium mole fraction of the In_xGa_1-xAs channel in the range 0.53-0.60, increasing the indium mole fraction lowers the threshold voltage and hence increases the drain current at the same gate bias     

某型杀伤枪榴弹引信弹道炸原因分析及再设计思考

通过对某型杀伤枪榴弹引信所发生的三次弹道炸的原因进行分析，提出用延期索替代延期药盘，并对有关机构进行再设计的对策。     

气体绝缘封闭电器的高速瞬变过程和现场试验

随着ＧＩＳ的工作电压不断提高和发展，一系列新的现象和问题也同时出现。从国外一些科研，设计，制造部门所研究发表的内容看，大致有隔离开关操作和高速瞬变过程，粒子影响和对干扰定位的技术，元件的监督，现场试验等课题，本文对以上问题加以综合介绍。     

开放、交流与凝聚--广州大学城广外学生活动中心设计

2003年夏天，广州大学城广州外语外贸大学一期项目的单体设计在相当短的设计周期中紧张地铺开。     

导弹模型的靶道试验技术研究

本文针对弹道靶道试验的基本特点,在分析研究导弹模型在无控飞行条件下的运动特征和试验测试方法的基础上,系统研究了导弹模型的靶道试验原理和方法、试验模型发射技术、导弹试验模型设计、试验数据处理方法等,最后进行了试验方法的验证试验.试验结果证明,采用本文所述的试验技术在弹道靶道中进行导弹模型的自由飞行试验是切实可行的.     

调谐质量阻尼器参数设计中的两个问题

本文以单自由度系统安装一个调谐质量阻尼器（简称TMD）为例，对抗风和抗震两类不同激励工况下TMD的参数设计问题进行了理论研究与对比分析。通过给出相对误差系数的概念，定量评价了不同的参数方法对TMD减振性能的影响程度。本文的研究为TMD的参数设计提供了理论指导。     

科技期刊编辑专业化和学者化是保证期刊学术质量的关键

一般科技期刊刊载的论文内容都具有很强的专业性,这就要求科技期刊编辑必须具有丰富的专业知识和较高的学术水平才能胜任编辑工作.从编辑过程的选题组稿、论文初审、选择审稿专家和编辑加工四个方面对此进行了阐述,指出了提高科技期刊编辑的相关专业知识和学术水平的措施.     

官能团化MCM-41在分离低碳醇-水混合物中的应用

采用一步法水热合成了介孔材料氯丙基官能团化的MCM-41(Cl(CH2)3-MCM-41)、氨丙基官能团化MCM-41(NH2(CH2)3-MCM-41)、甲基官能团化MCM-41(CH3-MCM-41)和氯丙基官能团化硅胶,并考察了它们作为气相色谱固定相分离低碳醇-水混合物的情况。实验结果表明,Cl(CH2)3-MCM-41能够分离低碳醇-水混合物中的各组分,随水、甲醇、乙醇、异丙醇、正丁醇极性的减小,各分子与Cl(CH2)3-MCM-41的作用力增强,保留时间延长。氯丙基官能团化硅胶、NH2(CH2)3-MCM-41)和CH3-MCM-41均不能分离低碳醇-水混合物,表明介孔材料规则的孔道结构、表面嫁接基团等对低碳醇-水混合物的分离有重要影响。同时考察了Cl(CH2)3-MCM-41的氯丙基负载量对低碳醇-水混合物分离效果的影响,结果表明,当氯丙基的摩尔分数为15%时,分离效果最佳。     

川东石炭系气藏排水采气工艺技术及其应用

四川盆地东部石炭系气藏是中国石油西南油气田公司的主力气藏之一，经过20多年的开发，出水气井增多、开发难度加大，必须进行排水采气才能维持正常生产。由于石炭系气藏大部分生产井存在井深、地层压力系数低、温度高、静液面深、复产后井口套压高的特点，常规排水采气工艺不能满足气藏的要求。针对这些难点，研究出深井高压气举、低压深井的优选管柱、深井高温泡排三项适合石炭系气藏的排水采气工艺，并在现场十多口井上进行了试验，增产效果显著。     

On the behavior of microstructures with multiple length scales

The current study aims to provide fundamental insight into the behavior of microstructures containing grain sizes that span multiple length scales. A commercial 5083 Al alloy was selected as the material of interest to facilitate comparison with recently published data. The materials studied here were prepared via the thermal consolidation of powders that were cryomilled for different times (i.e., 0, 2, 4, and 8 hours). Following consolidation, the resultant microstructure was characterized by an equiaxed grain morphology with a size distribution centered around 200∼300 nm. Dispersed among the 200- to 300-nm grains were coarse-grained regions or ligaments with a grain size ranging from 600 nm to 2 μm. The occurrence of coarse-grained regions is rationalized on the basis of recrystallization or subgrain coarsening, whereas the occurrence of equiaxed fine regions is proposed to be a result of continuous grain growth. Two types of microstructures were selected for study, containing coarse-grained volumes of approximately 28 pct and 43 pct that corresponded to an ultimate tensile strength (UTS) of 566 MPa and 535 MPa, and a fracture strain of 3.2 pct and 3.5 pct, respectively. The observed ductility and the relevant toughening mechanisms were discussed in light of the presence of multiple length scales.