Verification of ANSI C37.90.1 SWC test generator outputs

Awareness of fast transient events in the electrical power environment has increased with the release of related test standards (ANSI C37.90.1 and IEC 801-4) and with increased usage of solid state circuits in utility equipment. Reliable measurement of the fast transient test waveforms and repeatable performance of test setups are persistent problems for equipment manufacturers and users. The construction, characterization, and usage of two high voltage test dividers for measurement of fast transient test waveforms are described. Measurements on a C37.90.1 (SWC) test generator are presented along with tutorial background. Proposals for changes to the ANSI C37.90.1 specification are included     

Comparison of smoothness evaluation devices for power cablecompounds

A variety of data from different devices has been generated on the smoothness of shield products, but no direct comparison of compound smoothness for the devices themselves has been made. The purpose of this study was to compare four different methods for evaluating the smoothness of power cable compounds. The methods compared include: image analysis, laser scanning, mechanical profilometry and photomicroscopy with visual rating. Extruded tape samples of conductor shields, filled insulations and strippable shields were evaluated     

A bidding decision index for construction contractors

Results from applying the model on a sample of contractors, the majority of whom were international and operating in Egypt, reinforces the credibility of the developed methodology, claim the authors.     

Application of Raman Spectroscopy to Retinal Proteins

Raman spectroscopic studies on photoreactive retinal proteins are comprehensively described, including the basic physics of Raman scattering and illustrative examples of the types of information on the structure and function of the retinal chromophore and its environment which can be obtained from the vibrational Raman spectra. In addition, practical advice and recipes are given which should enable the reader to plan and eventually perform a Raman experiment in a photolabile retinal protein. A dominant role is played by the resonance Raman (RR) experiment with visible laser excitation which selectively probes the retinal chromophore. Much discussion is devoted to bacteriorhodopsin (bR) and its photocycle as a paradigm for a light-induced reaction of a retinal protein. Various time-resolved techniques are described to study the temporal evolution of the bR chromophore by probing RR spectra of intermediate states. Vibrational Raman spectra are interpreted in terms of structure and structural changes of the chromophore. RR spectroscopic studies on halorhodopsin, sensory rhodopsin, and visual pigments are reported, as well as on modified proteins in which retinal analogues are incorporated, and on site-specific mutants. Results of ultraviolet RR experiments which selectively probe the aromatic side chains in the protein backbone are reported. In addition, a promising new technique of near-infrared Raman excitation is discussed. Finally, application of coherent anti-Stokes Raman spectroscopy (CARS) to retinal proteins is reported.     

Minimizing sample evaporation in the environmental scanning electron microscope

The ElectroScan environmental scanning electron microscope (ESEM) enables wet samples to be observed by eliminating air but allowing water vapour into the sample chamber. However, evaporation from, and condensation on, the sample may occur during the pumpdown sequence used to reach this state, which means that the sample may not be in its natural state when viewed if due care is not taken. In this paper, the pumping system of the ESEM is described mathematically and expressions are derived for the evaporation and condensation. This treatment is then used to calculate the optimum pumpdown sequence. The importance of using the optimized procedure is illustrated by micrographs of fat emulsions.     

铝－锂合金中δ’（Al＿3Li）沉淀相时效粗化行为及体积分数的测定

对经固溶处理的二种Ａｌ－Ｌｉ合金（１．９４ｗｔ．％Ｌｉ和２．７５ｗｔ．％Ｌｉ）的时效过程进行了研究。结果表明：δ’的生长速率遵从Ｏｓｔｗａｒｄ粗化动力学。１．９４ｗｔ．％Ｌｉ合金δ’产生于时效过程中，而２．７５ｗｔ．％Ｌｉ合金的δ’产生于时效的前期阶段。前者的表现体积分数明显大于根据相图估算的数伍，真实体积分数则与此值接近；后者的体积分数低于根据相图估算的数值，这可能归咎于δ’固相线的位置、统计学误差及Ｌｉ更易在时效过程中贫化。     

New type of charged-particles detector based on point contacts formed in a GaAs-AlGaAs heterostructure by split-gates

We propose a new principle for a low temperature semiconductor detector of charged particles with possibly submicron lateral resolution based on point contacts formed in the 2-dimensional electron gas (2DEG) of a GaAs-Al_xGa_1-xAs heterostructure using split-gates. The detector operates up to liquid nitrogen temperatures. Impinging particles excite locally extra donors in the doping layer of the heterostructure. By measuring simultaneous increase in the conductances of 3 point contacts due to the impacts of charged particles the position of penetration is calculated using the Thomas-Fermi approximation for screening in 2DEG.     

Why should the steel industry do anything with their PCBtransformers?

EPA regulations force owners of PCB (polychlorinated biphenyl) equipment to carefully review regulatory compliance and develop PCB risk management programs. The EPA is currently planning new PCB regulations that may add additional PCB management requirements. The author briefly reviews the EPA regulations, highlighting the more commonly violated requirements. Several risk management techniques are presented and discussed. A method of quantifying PCB equipment owning cost is presented     

Detection of interphase instability from luminescence of reaction products

The reaction between chlorine and an alkaline solution of hydrogen peroxide is suggested for the investigation of chemothermocapillary convection [1].Vitebsk Branch of the Institute of Solid State and Semiconductors Physics, Academy of Sciences of Belarus, Vitebsk, Belarus. Translated from Inzhenerno-Fizicheskii Zhurnal, Vol. 66, No. 1, pp. 30–33, January, 1994.