美国电气设备现场评估认证

介绍现场评估的要求、流程和依据,并以电气控制柜现场评估为例,阐述UL 508A,NFPA 79对其关键部件、可逆电机控制器的技术要求,总结申请现场评估的要素和注意事项。     

Electrical traps in GaAs microwave f.e.t.s

Described is a rapid, sensitive technique for determining the activation energies for electron traps present in the channel of GaAs microwave field-effect transistors. The measurements can be made directly on the f.e.t.s. Taken together with systematic variation of growth procedures, the method can be applied toward identification and elimination of the traps.     

冬日电器的维护与保养

入冬了，人知冷知热，懂得把夏天的薄衫收起来，温暖的冬装穿上身。其实家电亦如此。劳碌了—夏天的空调、电扇要歇歇了，劳您费心收拾起来，来年再用时才能保持好状态；许久没用的浴霸、加湿器重新“上岗”了，但得容它们有个逐渐“适应”的时间，别一来就过度“劳累”了。     

电气测试

我们可以用几个小时来讨论测试技术:针床测试、移动探针(飞针测试)、电子束测试等离子体测试和光电测试等技术.今天,一个PCB工厂所涉及的是与电气测试过程和测试可靠性(即测试本身的有限范围和可靠性)相关的整体成本.人们总想以尽可能低的成本来100%测试全部生产的板.     

Electrical characteristics of r.f.-sputtered CdTe thin-films for photovoltaic applications

A method of preparing self-doped p- and n-type and In-doped n-type CdTe thin-films for photovoltaic applications has been developed using r.f. sputtering. Ohmic contacts to n-type films with contact resistivity less than 10^?2 Ω — cm² have been obtained. Schottky barrier diode test devices, formed by evaporation of various metals including Au on n-CdTe films, have been examined for electrical and photovoltaic evaluation of the sputtered films. Although S.B. diodes based on In doped films, prepared under Cd overpressure, show promising electrical and photovoltaic performance (V_oc ～ 315 mV, I_sc ～ 4.6mA/cm²), much improvement remains to be made by further control of dopant concentration and structural details of films.     

Electrical Engineering Hall of Fame: Stanford C. Hooper

Recounts the career and contributions of Stanford C. Hooper, who received the IRE Medal of Honor in 1934, for "the orderly planning and systematic organization of radio communication in the government service."     

Electrical Engineering Hall of Fame: Michael I. Pupin

In 1924, the Institute of Radio Engineers (IRE) selected Michael I. Pupin as the seventh recipient of its Medal of Honor. He was cited for his "fundamental contributions in the field of electrical tuning and the rectification of alternating currents used for signaling purposes". An influential electrical engineering educator and inventor, he had served as the president of the IRE in 1917 and had received the Edison Medal from the American Institute of Electrical Engineers (AIEE) in 1920. He also received the Pulitzer Prize in 1924 for his autobiography entitled From Immigrant to Inventor and served as president of the AIEE in 1925. His pioneering work on the so-called loading coil used in telephony brought him considerable fame and financial rewards. He was a mentor of such well-known pioneers in radioelectronics as Alfred N. Goldsmith and Edwin H. Armstrong.     

Electrical Engineering Hall of Fame: John A. Fleming

In 1933, the Institute of Radio Engineers (IRE) selected John A. Fleming as the recipient of its Medal of Honor. He was cited "for the conspicuous part he played in introducing physical and engineering principles into the radio art." Earlier, he had received the Hughes Medal of the Royal Society of London, in 1910, and the Faraday Medal of the British Institution of Electrical Engineers (IEE), in 1928. During his long career, he authored more than 100 technical papers and several influential textbooks. He is remembered as the inventor of the "Fleming valve," an thermionic diode which was a precursor of vacuum-tube amplifiers     

Electrical Engineering Hall of Fame: Charles F. Brush

In 1913, the American Institute of Electrical Engineers (AIEE) selected the inventor-entrepreneur Charles F. Brush as the fifth recipient of the Edison Medal. He was cited for his contribution to "the invention and development of the series arc lighting systems." The company he founded emerged as a leader in the field of outdoor lighting during the 1880s and introduced many urban residents to well-lighted streets for the first time. New York City's famous "Great White Way" was illuminated by Brush's arc lights and became a pattern for other cities and even small towns in the late 19th and early 20th centuries. These local white ways came to symbolize modernization and progress at the beginning of the electrical age.     

Electrical Engineering Hall of Fame: Charles F. Scott

Recounts the career and contributions of Charles F. Scott, who received the AIEE's Edison Medal in 1929 for "his contributions to the science and art of polyphase transmission of electrical energy."     

Electrical Engineering Hall of Fame: Cummings C. Chesney

In 1921, the American Institute of Electrical Engineers (AIEE) selected Cummings C. Chesney as the recipient of the Edison Medal. He was cited for his contributions to early developments in alternating current transmission". He later served as president of the AIEE during 1926 and 1927. He was known for his pioneering work with high-voltage power transmission.     

Electrical characteristics of the sparks produced by electrosurgical devices.

The electrical characteristics of the sparks produced between the active electrode and the biological tissue during electrosurgical procedures have been experimentally investigated. The results have shown that the minimum voltage required to initiate a spark depends on the applied voltage polarity resulting in electrosurgical voltage asymmetry. This voltage asymmetry is capable of producing dc levels that can result in tissue electrostimulation or direct current burns as discussed in this paper. The experimental setup and the conditions, under which the results have been obtained, including the techniques used to improve experimental reproducibility, are reported in detail.     

Electrical Engineering Hall of Fame: Louis W. Austin

The Institute of Radio Engineers (IRE) selected Louis W. Austin as the recipient of its Medal of Honor in 1927. He was cited for "his pioneer work in quantitative measurement and correlation of factors involved in radio wave transmission." He had served as the third president of the IRE in 1914 and authored numerous papers for the Proceedings of the IRE during the period from 1913 to 1932. He conducted systematic data collection and analysis of wave propagation phenomena as a longtime employee of the National Bureau of Standards. His work provided a scientific basis for the design of early transoceanic radio transmitters for the U.S. Navy and private communication companies.