Momentum Transfer Dependence of Two Types of the Broad Enhancement Phenomena： CO Spectra in the Valence Energy Region

Partial generalized oscillator strength densities of CO molecules related to the excitation of a 5σ or 1π electron are calculated by using multi-scattering self-consistent-field methods.Momentum transfer dependence of two types of the broad enhancement phenomena above the threshold with one-electron character,i.e. shape resonance and non-resonance enhancement,is studied.Our calculations show that the energy position of a non-resonance enhancement is related to the momentum transfer K.Therefore,electron impact based experiments can be used to identify the two types of the broad enhancement phenomena.     

Exact solutions for Belousov-Zhabotinskii reaction-diffusion system

Abstract. We consider the following simplified model for the Belousou-Zhabotinskii(B-Z)reaction:     

集成电路芯片封装可靠性知识

B-SCAN:(1)Show the x-sectional image from each inter-face.可以显示各个纵切面的平面图像(2)Detectable defects:Crack,Tilt and Void.可发现的失效现象:裂缝、倾斜、气泡(3)Merit:Analysis of the level of defects arepossible.优点:对平面的失效点进行分析C-SCAN:(1)Shows the horizontally x-sectioned imagesafter fours at an interface.显示水平剖面的图象(2)Detectable defects:Delamination,Die crack.可发现的失效现象:离层、芯片裂缝(3)Merit:The most precise inspection method.优点:最精确直观的检测方法(4)Wea…     

大钟拍声的调整实验

阐明大钟拍声的发生原理,并用大钟振动拍的理论模型说明拍的特性,从而控制清晰度。在实验钟上附着质量,根据附着质量位置的不同,能够改变其非对称程度,进一步调整拍频,同时用有限元分析的结果和等效圆环理论计算的结果对比。引入等效圆环理论,通过建立一个理论上带有附加质量的轴对称圆环模型,达到具有和大钟相同的振动特性。根据模型,得到在大钟特定位置附加的质量,以同时调整所需拍的清晰度和周期。在大钟多个位置进行实验,并进行有限元分析,验证了该理论的有效性。     

小灵通网络二次呼叫的深度分析

小灵通网络中的二次呼叫,是指用户处于覆盖良好的区域,第一次呼叫失败,但紧接着的第二次呼叫又能完成的现象.该现象在各地小灵通网络中或多或少存在,虽然发生频率不是很高,但会大大影响用户的QoS.     

X-band circularly polarized rectennas for microwave power transmission applications

Circularly polarized rectennas operating at X-band are studied in this paper. The quasi-square patches fed by aperture coupling are used as the circularly polarized receiving antennas, which are easily matched and integrated with the circuits of rectennas. The： double-layer structure not only minimizes the size of the rectennas but also decreases the effects of the circuits on the antenna. The receiving elements have broader bandwidth and higher gain than the single-layer patches. Two rectennas operating at 10GHz are designed, fabricated and measured. The voltage of 3.86V on a load of 200Ω is measured and a high RF-DC conversion efficiency of 75% is obtained at 9.98GHz. It is convenient for this kind of rectennas to form large arrays for high power applications.     

放大器输出端口过大造成的故障

末级放大器所辖用户反映信号不清,到用户家实地观察基本无信号,查放大器输入信号为33 dB,输出信号49 dB,测电压为28 V,证明输入信号有问题.到前级放大器检测输出信号电平，打开防水铝盖，用场强仪测得信号电平都在89dB左右，测电压为33V，基本正常，本级放大器无故障。此段-9电缆更换不久．不大可能出故障，且没有发现私拉乱接的破坏现象。断掉前级放大器输出馈电，     

“上海南亚”现象及其思考

“上海南亚”指我行业的上海南亚覆铜箔板有限公司。该公司2000年7月在上海南翔筹建，2001年3月投产，当年生产50万m^2环氧玻布基覆铜板，尚不引人注目。可是短短两年。到2003年，产量、销售额翻了近两翻，达到185万m^2和1．74亿元(RMB)，二期工程预计于2004年6月投产，产能将达到300万m^2玻布基和复合基覆铜板及500万m^2粘结片。     

微纳级双极晶体管的热耗散研究

对于双极性晶体管,由于自身存在的自加热现象,严重地影响着器件的特性。基于热电流方程、泊松方程及电流密度方程,在二维器件仿真环境下,进行了微纳级小尺寸npn双极性晶体管热现象的器件物理特性分析。重点研究了器件的集电极电流IC与晶格温度T的因变关系。研究结果显示,随着IC的增加,器件的晶格温度逐渐升高,VCE保持在3.0V、VBE达到最大值0.735V时,随器件晶格温度的升高VBE将减小。最后,笔者给出了描述晶体管温变关系的三维曲线。