被动补偿脉冲发电机涡流损耗的解析计算

在假设转子导电筒中涡流面电流与定子无槽电枢绕组面电流相同、相位相反的条件下,条件麦克斯韦方程组,通过分析被动补偿脉冲发电机导电筒中涡流分布,导出了被动补偿脉冲发电机导电筒涡流损耗的解析表达式,并计算了涡流损耗对25MW样机运行的影响。     

KTP和7.5mol%Nb:KTP晶体在Nd:YAG激光中的倍频和和频

本文在获得精确的7.5mol%Nb:KTP晶体的Sellmeier主折射率色散方程的基础上,计算7.5mol%Nb:KTP晶体对1.0642μm和1.3188μmNd:YAG激光的倍频和和频的型相位匹配曲线.通过研究KTP和7.5mol%Nb:KTP晶体的主折射率,双折射率和相位匹配,可以看出Nb掺入KTP晶体后产生的折射率和双折射率的色散和各向异型的变化是引起KTP晶体相位变化的根本原因.     

对自感现象中灯泡亮度的研究

本文通过对演示自感现象实验中灯泡亮度的问题讨论 ,对自感现象进行电路分析 ,加深了对自感现象的认识     

大学物理虚拟实验的网络教学系统

介绍了基于当前Internet网络环境实现仿真实验远程教学的方案和技术,为各种实验的远程教学开发与应用提供了一种可行的新模式。     

Generalized Steiner systems GS4 (2, 4, v,g) for g = 2, 3, 6

Generalized Steiner systems GS_d(t, k, v, g) were first introduced by Etzion and used to construct optimal constant‐weight codes over an alphabet of size g + 1 with minimum Hamming distance d, in which each codeword has length v and weight k. Much work has been done for the existence of generalized Steiner triple systems GS(2, 3, v, g). However, for block size four there is not much known on GS_d(2, 4, v, g). In this paper, the necessary conditions for the existence of a GS_d(t, k, v, g) are given, which answers an open problem of Etzion. Some singular indirect product constructions for GS_d(2, k, v, g) are also presented. By using both recursive and direct constructions, it is proved that the necessary conditions for the existence of a GS₄(2, 4, v, g) are also sufficient for g = 2, 3, 6. © 2001 John Wiley & Sons, Inc. J Combin Designs 9: 401–423, 2001     

含杀菌、吸附双功能基棉纤维的制备与性能

化学改性;吸附剂;杀菌剂;含杀菌、吸附双功能基棉纤维的制备与性能     

Fe~(3 )/TiO_2/SiO_2复合纳米微粒的合成及光催化降解NO_2~-

采用溶胶 -凝胶法制备了 Ti O2 / Si O2 和不同浓度 Fe3 掺杂的 Fe3 / Ti O2 / Si O2 复合纳米粉末 ,并利用XRD、BET、UV-vis等手段研究了 Ti O2 / Si O2 及掺铁形成的 Fe3 / Ti O2 / Si O2 复合微粒的表面结构形态变化 ,以及对污染物 NO- 2 光催化降解的影响 .结果表明 ,Fe3 / Ti O2 / Si O2 (ω( Fe3 ) =1 .5 % ,m( Ti)∶ m( Si) =2∶ 1 )具有最佳活性 ,样品呈晶化度较低的锐钛矿结构 .Fe3 掺杂导致晶粒的增大 ,稳定性降低 ,大大提高了半导体的光催化活性 ,有利于对低浓度 NO- 2 的光催化降解     

α-Fe_2O_3掺杂对In_2O_3电导和气敏性能的影响

用化学共沉淀法制备了α－Ｆｅ２Ｏ３掺杂的Ｉｎ２Ｏ３纳米晶微粉,研究了α－Ｆｅ２Ｏ３掺杂对Ｉｎ２Ｏ３电导和气敏性能的影响．结果表明,α－Ｆｅ２Ｏ３和 Ｉｎ２Ｏ３间可形成有限固溶体Ｉｎ２－ｘＦｅｘＯ３（０≤ｘ≤０．４０）;Ｆｅ３＋对 Ｉｎ２Ｏ３晶格中Ｉｎ３＋格位的部分取代,大大增强了阴阳离子间的结合力,导致材料中氧空位Ｖｏｘ数骤降、自由电子的浓度变稀和电导下降．ｎ（Ｆｅ３＋）：ｎ（Ｉｎ３＋）＝５：５的共沉淀粉于 ８００℃下灼烧 ４ ｈ所得的 α－Ｆｅ２Ｏ３掺杂Ｉｎ２Ｏ３传感器元件,对 ４５μｍｏｌ·Ｌ－１Ｃ２Ｈ５ＯＨ的灵敏度达５４．０,为相同浓度干扰气体汽油的８倍多．     

氢化物发生微分电位溶出法测定人尿、头发及自来水中痕量锡

研究了氢化物发生微分电位溶出法测定人尿、头发及自来水中痕量锡的方法,该法能有效地消除共存离子的干扰。详细研究了锡化氢发生以及微分电位溶出法测定锡的最佳条件。方法的线性范围0－150mg.ml^-1,检出限2．5ng.ml^-1,成功地用于自来水、人尿及头发痕量锡的测定。测定发样中304．5ng.g^-1锡时,回收率为100．3％,相对标准偏差为5．1％（n=6)。     

Oxidative Dehydrogenation of Ethane to Ethylene over LiCl/MnOx/PC Catalysts

The catalytic stability of LiCl/MnO_x/PC catalyst have been investigated, the deactivation mechanism was discussed. The experimental results show that ethane conversion decreases and ethylene selectivity keeps about 90% as reaction time increases. The main deactivation reasons of LiCl/MnO_x/PC catalyst for oxidative dehydrogenation of ethane (ODHE) to ethylene are the transition of active species Mn₂O₃ to MnO species and the loss of active component Cl in catalyst. Instead of ethane with FCC tailed‐gas, the stability of LiCl/MnO_x/PC catalyst has been largely improved.