Westinghouse Electric

About: Westinghouse Electric is a company organization based out in Cranberry Township, Pennsylvania, United States. It is known for research contribution in the topics: Brake & Signal. The organization has 27959 authors who have published 38036 publications receiving 523387 citations.

Elastic Constants of Iron from 4.2 to 300°K

Abstract: The zero-field elastic constants of iron have been measured from 4.2 to 300\ifmmode^\circ\else\textdegree\fi{}K using the ultrasonic pulse technique. Extrapolation of the data to absolute zero gives ${c}_{11}=2.431\ifmmode\pm\else\textpm\fi{}0.008$, ${c}_{12}=1.381\ifmmode\pm\else\textpm\fi{}0.004$, and ${c}_{44}=1.219\ifmmode\pm\else\textpm\fi{}0.004$, all expressed in units of ${10}^{12}$ dyne ${\mathrm{cm}}^{\ensuremath{-}2}$. The corresponding limiting value of the Debye temperature is ${\ensuremath{\theta}}_{0}=(477\ifmmode\pm\else\textpm\fi{}2)\ifmmode^\circ\else\textdegree\fi{}$K. Using this figure, the low-temperature heat capacity data for iron have been reanalyzed assuming the presence of a spin-wave contribution to the specific heat, i.e., the heat capacity is assumed to follow the relation $C=\ensuremath{\gamma}T+\ensuremath{\beta}{T}^{3}+\ensuremath{\alpha}{T}^{\frac{3}{2}}$. A least squares fit of $\frac{(C\ensuremath{-}\ensuremath{\beta}{T}^{3})}{T}$ versus ${T}^{\frac{1}{2}}$ gives $\ensuremath{\gamma}=(11.7\ifmmode\pm\else\textpm\fi{}0.1)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}4}$ cal ${\mathrm{mole}}^{\ensuremath{-}1}$ ${\mathrm{deg}}^{\ensuremath{-}2}$, $\ensuremath{\alpha}=(2\ifmmode\pm\else\textpm\fi{}1)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}5} \mathrm{cal} {\mathrm{mole}}^{\ensuremath{-}} {\mathrm{deg}}^{\ensuremath{-}\frac{5}{2}}$. There is agreement, within experimental error, between the latter figure and the theoretical estimate of $\ensuremath{\alpha}=0.8\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}5} \mathrm{cal} {\mathrm{mole}}^{\ensuremath{-}1} {\mathrm{deg}}^{\ensuremath{-}\frac{5}{2}}$ obtained from the low-temperature magnetization data of Fallot. From the room temperature elastic constants, the compressibility of iron is found to be $K=(5.95\ifmmode\pm\else\textpm\fi{}0.02)\ifmmode\times\else\texttimes\fi{}{10}^{\ensuremath{-}13}$ ${\mathrm{cm}}^{2}$ ${\mathrm{dyne}}^{\ensuremath{-}1}$, which agrees exactly with the static value obtained by Bridgman.

Cognitive Systems Engineering

Abstract: This paper presents an approach to the description and analysis of complex Man?Machine Systems (MMSs) called Cognitive Systems Engineering (CSE). In contrast to traditional approaches to the study of man?machine systems which mainly operate on the physical and physiological level, CSE operates on the level of cognitive functions. Instead of viewing an MMS as decomposable by mechanistic principles, CSE introduces the concept of a cognitive system: an adaptive system which functions using knowledge about itself and the environment in the planning and modification of actions. Operators are generally acknowledged to use a model of the system (machine) with which they work. Similarly, the machine has an image of the operator. The designer of an MMS must recognize this, and strive to obtain a match between the machine's image and the user characteristics on a cognitive level, rather than just on the level of physical functions. This article gives a presentation of what cognitive systems are, and of how CSE can contribute to the design of an MMS, from cognitive task analysis to final evaluation.

Power electronics in electric utilities: static VAR compensators

Abstract: The author deals with dynamic VAR compensation of electric power systems, applying power electronics for reactive power generation and control. After an overview of the emergence and status of modern, solid-state VAR compensators in utility and industrial applications, it is shown how dynamic VAR compensation increased transmittable power by providing voltage support, transient stability improvement, and power oscillation damping in electric power transmission systems. Methods of reactive power generation and control using thyristor-controlled reactors, with fixed and thyristor-switched capacitors or modern gate-turn-off (GTO) power converters that can function without AC capacitors or reactors, are described. A summary is included of the control structure and operation to provide the desired characteristics and performance in power systems applications. >