Analysis of line-commutated converters during unbalanced operatingconditions

In this paper, a method of analyzing the salient performance characteristics of line-commutated power converters during unbalanced operating conditions is presented. Simple analytical relationships are established which relate the negative-sequence component of AC current to the negative-sequence component of voltage. These results are verified using a detailed valve-by-valve simulation of a line-commutated inverter connected to a photovoltaic array     

A numerical investigation on the geometry dependence of the crack growth resistance in CT specimens

The influence of the specimen thickness B and the ligament length b on the J _R -curves is numerically investigated for CT specimens. The thickness effect is taken into account with 2-D analyses by dividing a plain sided specimen into a plane stress part and a plane strain part. The fracture process is controlled by experimentally determined critical values of the crack tip opening displacement for crack growth initiation (CTOD_i) and the crack tip opening angle for stable crack growth (CTOA_C). It is shown that for the global behaviour of a plain sided specimen, the B/b ratio is essential. The difference between the geometry dependence of the initiation value of the J-integral and the geometry dependence of the slope of the J _R -curves is also shown.     

Marcian E. Hoff Jr

The author presents a profile of Marcian E.(Ted) Hoff, the architect of the first commercial microprocessor and the single chip coder/decoder (codec). Hoff has turned a lifelong interest in collecting electronic components into a career as high-tech detective, helping patent attorneys defend their cases. In his crowded home workshop, Hoff has over 15,000 ICs inventoried and filed, along with various PCs, oscilloscopes and other instruments     

A theoretical and numerical analysis of the measured equation ofinvariance

The measured equation of invariance (MEI) has been previously introduced to efficiently and accurately handle the boundary truncation for finite methods. The present authors give a theoretical analysis that provides several important insights into the capabilities of the MEI. From the numerical study, they can explain why the MEI works better than one would expect. Both the theoretical and the numerical analyses demonstrate that the accuracy of the solution is dependent on the electrical size of the geometry as well as the distance between the mesh boundary and the geometry. From the analysis, the authors propose a new set of metrons that is less sensitive to the excitation than the previously proposed sinusoidal metrons     

Effects of hot carrier induced interface state generation insubmicron LDD MOSFET's

A two-dimensional numerical simulation including a new interface state generation model has been developed to study the performance variation of a LDD MOSFET after a dc voltage stress. The spatial distribution of hot carrier induced interface states is calculated with a breaking silicon-hydrogen bond model. Mobility degradation and reduction of conduction charge due to interface traps are considered. A 0.6 μm LDD MOSFET was fabricated. The drain current degradation and the substrate current variation after a stress were characterized to compare the simulation. A reduction of the substrate current at V_g ≃0.5 V_d in a stressed device was observed from both the measurement and the simulation. Our study reveals that the reduction is attributed to a distance between a maximum channel electric field and generated interface states     

Dielectric measurements using a rational function model

A recently proposed rational function model for the aperture admittance of 50 ohm Teflon filled coaxial lines in contact with a homogeneous dielectric is experimentally validated. A calibration technique of the automatic network analyzer utilizing standard terminations and time domain gating is used. Uncertainties in the dielectric properties of reference liquids do not enter the calibration procedure. Experimental results for water and methanol are compared with estimated values. A model expression for the sensitivity of the probe is validated. The sensitivities of two coaxial line probes for the measurements made are determined. Results obtained using the new model are compared with those of other workers     

Introduction to the special section: professional communication inRussia

There is a rising interest within the world community in what is occurring in professional communication in Russia, and in the social and market opportunities that will appear there in the future. We live in a world in which the pace of change is more rapid than at any time in our history. The most important aspect of this change is the fact that we are making a transition to a democratic society at the same time as we are in the process of establishing the principles of a market economy. Russia is a country with enormous reserves of raw materials, vast territories, and rich intellectual resources. And now, as Russia is experiencing a painful transition to a market economy, the nation's economic potential becomes more and more dependent on the sophistication of its infrastructure. That is the reason why the information technologies and professional communication have become key factors of social progress. The Russian centers of research and industry are widely dispersed geographically, in such cities as Vladivostok, Irkutsk, Novosibirsk, Tomsk, Ekaterinburg, Saint Petersburg and Moscow. The last three or four years have seen a sharp increase in the demands for business information, electronic mail and communications for far-flung business and financial operations