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Institution

Westinghouse Electric

CompanyCranberry Township, Pennsylvania, United States
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 & Circuit breaker. The organization has 27959 authors who have published 38036 publications receiving 523387 citations.


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Journal ArticleDOI
TL;DR: In this paper, the effect of service interruptions on a single-server system with stationary compound Poisson input and general independent service times is studied, the latter being subject to random interruptions of independently but otherwise arbitrarily distributed durations.
Abstract: SUMMARY A single-server system with stationary compound Poisson input and general independent service times, the latter being subject to random interruptions of independently but otherwise arbitrarily distributed durations, is studied. For a variety of service-interruption interactions (including the preemptiverepeat) the distributions of busy period duration, of queue length, and of waiting time are characterized by transforms and by moments. Applications are made to priority scheduling problems. MANY situations in which waiting lines develop are characterized by the occurrence of interruptions in customer service. Such interruptions may be caused by breakdowns of a machine that provides service, for example, an electronic computer. Also, if certain customers are assigned priority, then the appearance of one of these may bring about an interruption in the servicing of low-priority customers. In practice it would not be surprising to find systems that experience interruptions of both sorts. In this paper we consider the effect of service interruptions upon a waiting-line process of the following kind: customers appear in accordance with a stationary compound Poisson process (i.e. bunches of customers arrive randomly), and are served in turn by a single facility. The basic customer servicing times are independently, identically, but otherwise arbitrarily, distributed. Interruptions appear at random, in the sense that, if the system is currently free of interruption, the time until the next interruption occurs is exponentially distributed. Interruption durations are identically, independently and arbitrarily distributed. Without interruptions the process described has been discussed by Gaver (1959); the present paper is an adaptation of the approach of the latter paper to the needs of the interruption problem. Previous treatments of similar problems, emphasizing priorities, have been given by Cobham (1954), Stephan (1956), Kesten and Runnenberg (1957), White and Christie (1958), Morse (1958, Chapter 9) and Miller (1960). The influence of service interruptions upon waiting-line behaviour cannot be investigated without specifying in detail the interaction between the interruption process and the service process. Throughout the present paper it will be assumed that all interruptions occurring during a particular customer's service period must take effect during, or immediately after, that period. Thus interruptions may be preemptive, summarily breaking in upon a service in progress, or postponable to the end of that period, but not beyond. If interruptions are preemptive it may be possible to resume service from the point at which interruption took place when the interruption is cleared; such an interaction (between service and interruption) is called

424 citations

Journal ArticleDOI
TL;DR: In this paper, compliance expressions for compact type (CT) and WOL specimens have been formulated for a wide range of crack lengths (0.2⩽a/W ⩽ 0.975) using results from Newman's modified boundary collection techniques and Wilson's deep crack analysis.
Abstract: Elastic compliance expressions for compact type (CT) and WOL specimens have been formulated for a wide range of crack lengths (0.2 ⩽a/W ⩽ 0.975) using results from Newman's modified boundary collection techniques and Wilson's deep crack analysis. The location of the axis of rotation of the specimen arms at various crack lengths has been calculated and subsequently used in a proposed extrapolation technique to predict compliance at any location of the specimen convenient for measuring deflection during a crack growth test. The predicted compliances were found to be in excellent agreement with expreimental values for the two specimen types considered. Compliance expressions are also included for the center crack tension specimen.

423 citations

Journal ArticleDOI
TL;DR: In this paper, a set of SiC phonon dispersion curves were constructed from first-order Raman scattering data using the existence of polytypes and the symmetry type of each phonon mode was determined by polarization analysis and the modes were further classified by the use of a standard large zone.
Abstract: Phonon dispersion curves for SiC have been constructed from first-order Raman scattering data. The method used is a new one that exploits the existence of polytypes. Excitation by an argon ion laser made possible the observation of nine one-phonon lines in $4H \mathrm{SiC}$, 16 lines in $15R$, and 14 lines in $21R$. The symmetry type of each phonon mode was determined by polarization analysis, and the modes were further classified by the use of a standard large zone. The three groups of one-phonon lines, together with 15 lines previously reported for $6H \mathrm{SiC}$, were then all assigned to their positions in a single large-zone plot, to yield a set of SiC phonon dispersion curves comparable with those obtained for other materials by neutron diffraction. The results verify the existence of a common phonon spectrum for all SiC polytypes in the axial direction. Longitudinal and transverse acoustic velocities are obtained from the dispersion curves, and are in good agreement with experimental values. Thus, optic modes in polytypes give information on acoustic properties. All SiC polytypes have in common a set of strong modes in which the Si and C sublattices vibrate against each other. The anisotropy of one of these modes varies with polytype in the same way as the $\frac{c}{a}$ axial ratios. Both the anisotropy and the $\frac{c}{a}$ ratio are related empirically to the percentage of hexagonal planes in the polytype stacking arrangement.

423 citations

Journal ArticleDOI
TL;DR: In this article, the authors analyzed the physical mechanism of secondary electron emission under the impact of high-speed heavy particles and showed that the yield is proportional to the rate of energy loss of the incident particles.
Abstract: The physical mechanism of secondary electron emission under the impact of high-speed heavy particles is analyzed. The treatment is based on the formation of secondaries according to the Bohr-Bethe theory of ionization, the diffusion of the slow secondaries to the surface, and their subsequent escape in the vacuum. The yield is found to be proportional to the rate of energy loss of the incident particles, and it is shown to be essentially the same for all metals, independent of their work function, conductivity, and other bulk properties. The observed energy distribution of the secondaries, the effect of adsorbed layers and the dependence of the yield on temperature, particle charge, and velocity are found to be explained in terms of this mechanism. The application to the general problem of the escape of electrons from metals and to the study of electron capture and loss by ions passing through solids is discussed.

422 citations

Journal ArticleDOI
TL;DR: A new principle of person-computer interaction, visual momentum, is captured, which captures knowledge about the mechanisms that support the identification of “relevant” data in human perception so that display system design can support an effective distribution of user attention.
Abstract: Computer display system users must integrate data across successive displays. This problem of across-display processing is analogous to the question of how the visual system combines data across successive glances (fixations). Research from cognitive psychology on the latter question is used in order to formulate guidelines for the display designer. The result is a new principle of person-computer interaction, visual momentum, which captures knowledge about the mechanisms that support the identification of “relevant” data in human perception so that display system design can support an effective distribution of user attention. The negative consequences of low visual momentum on user performance are described, and display design techniques are presented to improve user across-display information extraction.

422 citations


Authors

Showing all 27975 results

NameH-indexPapersCitations
Takeo Kanade147799103237
Martin A. Green127106976807
Shree K. Nayar11338445139
Dieter Bimberg97153145944
Keith E. Gubbins8546635909
Peter K. Liaw84106837916
Katsushi Ikeuchi7863620622
Mark R. Cutkosky7739320600
M. S. Skolnick7372822112
David D. Woods7231820825
Martin A. Uman6733816882
Michael Keidar6756614944
Terry C. Hazen6635417330
H. Harry Asada6463317358
Michael T. Meyer5922526947
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Performance
Metrics
No. of papers from the Institution in previous years
YearPapers
20231
202217
202135
202063
201946
201860