A new lateral MOS-gated thyristor with controlling base-current

A new lateral MOS-gated thyristor, called the Base-Current-Controlled Thyristor, is described. This device is designed so that most holes at the on-stage reach the P base through the floating P⁺ region adjacent to the P base and the on-state MOSFET. At the turn-off stage, the interruption of the hole current to the P base due to switching off the above MOSFET occurs simultaneously with the conventional turn-off operation. The concept of this device is verified experimentally by using the fabricated lateral device with the external MOSFET. This device exhibits a better trade-off relation between the on-state voltage and the turn-off time compared uith the conventional MOS-gated thyristor     

Evaluating the impact of CASE: an empirical comparison of retrospective and cross-sectional survey approaches

The purpose of this paper is to evaluate two methods of assessing the productivity and quality impact of Computer Aided Software Engineering (CASE) and Fourth Generation Language (4GL) technologies: (1) by the retrospective method; and (2) the cross-sectional method. Both methods involve the use of questionnaire surveys. Developers' perceptions depend on the context in which they are expressed and this includes expectations about the effectiveness of a given software product. Consequently, it is generally not reliable to base inferences about the relative merits of CASE and 4GLs on a cross-sectional comparison of two separate samples of users. The retrospective method that requires each respondent to directly compare different products is shown to be more reliable. However, there may be scope to employ cross-sectional comparisons of the findings from different samples where both sets of respondents use the same reference point for their judgements, and where numerical rather than verbal rating scales are used to measure perceptions.     

Conditions for reliable dewatering systems based on voidless drainage in slightly permeable soils

Conclusions 1. Use of dewatering systems based on voidless drainage is most effective when dewatering slightly permeable soils in regions with a deep seasonal frost. 2. Two-story drainage with the upper and lower stories spaced 30 m apart accelerates the discharge of gravitational water from the arable layer. Results of observations on two-story drainage in experimental-production sections indicated that it discharges 2 – 3.8 times more water than systematic tubular drainage with an interdrain spacing of 10 m and a 0.2-m thick three-dimensional filter of a sandy-gravelly mixture. 3. It is recommended to use crushed stone and porous-clay gravel with a fineness of 10 – 20 mm as a filler. In that case, protection of the drain filler is, as a rule, required only from the intrusion of soil from above during construction in cohesive soils with a plasticity indexW _p≥7. 4. seepage rate in a voidless drain should be lower than the scouring velocity for the soil in which the voidless drainage is placed. In the opposite case, it is necessary to lower the grade of the drains or select a filler gradation such that the seepage rate in the drain be lower than the scouring velocity. Translated from Gidrotekhnicheskoe Stroitel’stvo, No. 8, pp. 41–43, August, 1998.     

Cholesterol and vascular disease. Study of pravastatin

Variations in lipid profile and incidence of vascular events were evaluated. Group 1 had a 29.3% reduction of total and a 38.3% reduction of LDL cholesterol as against reductions of 9% and 9.6% respectively in group 2. No significant difference was observed between the two groups as far as the vascular events considered were concerned. Pravastatin is an effective and safe drug. The lack of influence on the evolution of vascular disease would appear to be correlated to the small number of subjects studied and the short follow-up.     

Synthesis and analysis of transformer-isolated converters

A systematic and straightforward procedure is developed for the synthesis and analysis of transformer-isolated power converters. The procedure can be used to determine the ranges of duty-ratio over which the transformer-isolated power converters of a given class can be operated without transformer saturation. The procedure can also be used to study the dependence of the power converter switch stresses on duty-ratios. This information is useful in the selection of the transformer-isolated power converter most suitable for a given application and in the design of this power converter with minimum switch stresses, high power density, and low cost     

Experience in High-Temperature Thermomechanical Treatment with Helical Reduction in the Production of Axisymmetric Parts

Metal Science and Heat Treatment -