Analysis of the time response of multiconductor transmission lineswith frequency-dependent losses by the method ofconvolution-characteristics

A new method for analysis of the time response of multiconductor transmission lines with frequency-dependent losses is presented. This method can solve the time response of various kinds of transmission lines with arbitrary terminal networks. Particularly, it can analyze nonuniform lines with frequency-dependent losses, for which no effective method for analyzing their time response exists. This method starts from the frequency-domain telegrapher's equations. After decoupling and inversely Fourier transforming, then a set of decoupled time-domain equations including convolutions are given. These equations can be solved with the characteristic method. The results obtained with this method are stable and accurate. Two examples are given to illustrate the application of this method to various multiconductor transmission lines     

Modeling ion implantation of HgCdTe

Ion implantation of boron is used to create n on p photodiodes in vacancy-doped mercury cadmium telluride (MC.T). The junction is formed by Hg interstitials from the implant damage region diffusing into the MC.T and annihilating Hg vacancies. The resultant doping profile is n⁺/n^-/p, where the n⁺ region is near the surface and roughly coincides with the implant damage, the n^- region is where Hg vacancies have been annihilated revealing a residual grown-in donor, and the p region remains doped by Hg vacancy double acceptors. We have recently developed a new process modeling tool for simulating junction formation in MC.T by ion implantation. The interstitial source in the damage region is represented by stored interstitials whose distribution depends on the implant dose. These interstitials are released into the bulk at a constant, user defined rate. Once released, they diffuse away from the damage region and annihilate any Hg vacancies they encounter. In this paper, we present results of simulations using this tool and show how it can be used to quantitatively analyze the effects of variations in processing conditions, including implant dose, annealing temperature, and doping background.     

压差式漏率测试仪的实验研究

将薄膜电容真空计的测量室接于被测密闭容器，静态真空室接于一个比较容器，即组成一台压差式漏率测试仪。首先使两容器压力平衡，真空计读数为零。当被测容器存在漏孔时，真空计薄膜两侧形成压差，真空计指示读数，继而计算出该容器的漏率。应用商品真空计在抽真空测试时，检测的最小可测漏率达10－4～10-5Pa·L／s；而在充压测试时，因受气体温度变化的影响，灵敏度会降低几个量级。该仪器有可能具备寻找漏孔位置和确定漏孔漏率的功能。     

环保型隧道防火涂料的研究

介绍了国内外公路隧道、铁路隧道及地铁火灾情况 ,研制出一种可在潮湿环境中使用、火灾发生时无有害气体产生的环保型隧道防火涂料。涂层厚度 18～2 0 mm,耐火极限达 3小时。为防止涂料加水拌和后沉淀分层 ,增加涂料的和易性 ,研制出一种分散剂。     

等偏移距自动初至静校正

茅金根 ,梁秀文 ,杨午阳 ,冯有奎 .等偏移距自动初至静校正 .石油地球物理勘探 ,2 0 0 2 ,37(5 ) :4 6 9～ 4 72　　本文提出一种自动计算静校正量的新方法。它首先在等偏移距道集内对相邻道的初至波采用高精度相关构建一个关于炮、检时差的超大矩阵方程 ,然后采用优化统计迭代算法求解炮点和检波点的静校正量 ,并用概率分布函数确定精确的炮、检静校正量 ,最后用误差校正函数消除炮、检静校正误差。实际资料处理结果表明 ,本方法自动、省时、精度高。     

利用新型场效应管(QFET)的正向变换器

介绍了单端正向变换器基本电路，重点叙述带三路调节DC电压的100KHZ180W离线电源。它采用具有低导电阻RDS和低栅极电荷Qg的新型场效应管（QFET）作为变换电路的主开关器件，降低了电源开关损耗并提高了效率3%-5%。     

Next-day electricity-price forecasting using a hybrid network

The paper proposes a novel method of forecasting short-term electricity price based on a two-stage hybrid network of self-organised map (SOM) and support-vector machine (SVM). In the first stage, a SOM network is applied to cluster the input-data set into several subsets in an unsupervised manner. Then, a group of SVMs is used to fit the training data of each subset in the second stage in a supervised way. With the trained network, one can predict straightforwardly the next-day hourly electricity prices. To confirm its effectiveness, the proposed model has been trained and tested on the data of historical energy prices from the New England electricity market.     

世界钻井史上的第一支钻头——圜刃

在人类文明史上,中华民族文明是全球九个独立起源的文明之一(其余八个为古埃及文明、两河流域文明、古印度文明、爱琴-米诺斯文明、南俄文明、奥尔梅克文明、玛雅文明、查文文明)。在世界文化史上,中华民族文化是世界五大文化圈之一(其余四个是西方基督教文化圈、东方东正教文化圈、伊斯兰教文化圈和印度     

Hydrothermal Reaction Mechanism and Pathway for the Formation of K2Ti6O13 Nanowires

Calculations and detailed first principle and thermodynamic analyses have been performed to understand the formation mechanism of K₂Ti₆O₁₃ nanowires (NWs) by a hydrothermal reaction between bulk Na₂Ti₃O₇ crystals and a KOH solution. It is found that direct ion exchange between K⁺ and Na⁺ plus H⁺ interactions with [TiO₆] octahedra in Na₂Ti₃O₇ promote the formation of an intermediate H₂K₂Ti₆O₁₄ phase. The large lattice mismatch between this intermediate phase and the bulk Na₂Ti₃O₇ structure, and the large energy reduction associated with the formation of this intermediate phase, drive the splitting of the bulk crystal into H₂K₂Ti₆O₁₄ NWs. However, these NWs are not stable because of large [TiO₆] octahedra distortion and are subject to a dehydration process, which results in uniform K₂Ti₆O₁₃ NWs with narrowly distributed diameters of around 10 nm.     

镁钴铝类水滑石催化合成安息香甲醚

采用共沉淀法制备了镁钴铝类水滑石化合物(MgCoAl-HTLcs),并用 X 射线衍射、扫描电子显微镜、NH_3程序升温脱附等方法对 MgCoAl-HTLcs 进行了表征,并以 MgCoAl-HTLcs 为催化剂催化苯甲醛与甲醇反应合成安息香甲醚,研究了n(Mg):n(Co):n(Al)、催化剂用量、原料配比、反应温度、反应时间对合成反应的影响。表征结果显示,MgCoAl-HTLcs 的晶相完整,表面主要为弱酸、弱碱性。催化合成安息香甲醚的适宜条件为:MgCoAl-HTLcs 催化剂用量0.10 g(约为原料总质量的0.23%),n(Mg):n(Co):n(Al)=0.4:1.6:1.0,V(苯甲醛):V(甲醇)=3:50,反应温度50℃,反应时间150 min。在此条件下,苯甲醛的平衡转化率达77.49%,安息香甲醚选择性接近100%。为洁净合成安息香甲醚开辟了一条新的途径。