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871.
The paper is concerned with two unit cold standby systems having one regular repairman and one expert repairman. The expert is called only if the regular repairman is not able to complete the repair within some toletable (patience) time. In model 1, it is assumed that an expert, on his arrival, gives instructions to the regular repairman for completing the repair, in model 2, it is assumed that the expert himselg takes over the system and the regular repairman leaves the repair in the presence of the expert. In model 3, there is no provision of calling the expert. Techniques of the semi-Markov processes and regenerative processes are used to obtain various measures of system effectiveness and profit incurred. A pairwise comparison of model 1 is made with model 2 and model 3 through graphs. 相似文献
872.
873.
We estimate the string tension by looking at Wilson loops and measuring the correlation between Wilson lines at g2 = 1.0 for lattice SU(3). The bound is larger than the previous results. The mass of the 0++ glueball is also estimated. The finite size effects on these quantities are shown to be large by comparing results on a 63 × 10 lattice with those on 94 lattice. 相似文献
874.
This paper presents the analysis of a two unit cold standby system with random arrival time of a server. The failure and repair times of each unit are assumed to be correlated and their joint density is taken as bivariate exponential. Using the regenerative point technique, various reliability characteristics of the system have been obtained. The behaviour of MTSF and steady state availability have also been studied through graphs. 相似文献
875.
Gupta A. Peng Fang Song M. Ming-Ren Lin Wollesen D. Chen K. Hu C. 《Electron Device Letters, IEEE》1997,18(12):580-582
We present an efficient and accurate method to characterize the physical thickness of ultrathin gate oxides (down to 25 Å) and the effective polysilicon doping of advanced CMOS devices. The method is based on the model for Fowler-Nordheim (F-N) tunneling current across the gate oxide with correction in gate voltage to account for the polysilicon-gate depletion. By fitting the model to measured data, both the gate oxide thickness and the effective poly doping are unambiguously determined. Unlike the traditional capacitance-voltage (C-V) technique that overestimates thin-oxide thickness and requires large area capacitor, this approach results in true physical thickness and the measurement can be performed on a standard sub-half micron transistor. The method is suitable for oxide thickness monitoring in manufacturing environments 相似文献
876.
M. Andreis J. L. Koenig M. Gupta S. Ramesh 《Journal of Polymer Science.Polymer Physics》1995,33(10):1449-1460
Molecular dynamics and structure of uncured and cured melamine-formaldehyde resins isotopically 15N enriched at amine sites were studied by solid-state 15N nuclear magnetic resonance (NMR). Spectra recorded with direct (DP) and cross-polarization (CP) pulse sequences reflect two motionally different regions arising from similar chemical structures. DP spectra of uncured resins at higher temperatures have narrow lines and the detection of slightly different structural units is possible. With increasing crosslinking resonances broaden and overlap and the direct detection of individual signals in cured resins is not possible. On the basis of variable contact time, variable spinning speed, and interrupted decoupling experiments three protonated and one nonprotonated group of signals are identified in the CP spectra for all samples. Short polarization-transfer rates, TNH, for nonprotonated nitrogen in uncured and lightly cured samples reveal more effective hydrogen bonding in viscous and rubber-like resins compared to the highly cured rigid resins. The rigid portions of the resins exhibit longer T1 and short T1ρ relaxation times, while the shorter T1 times and longer T1ρ times are associated with the more mobile portion of samples. ©1995 John Wiley & Sons, Inc. 相似文献
877.
Effect of mutual coupling on the performance of adaptive arrays 总被引:36,自引:0,他引:36
The effect of mutual coupling between array elements on the performance of adaptive arrays is examined. The study includes both steady state and transient performance. An expression for the steady state output signal-to-interference-plus-noise ratio (SINR) of adaptive arrays, taking into account the mutual coupling between the array elements, is derived. The expression is used to assess the steady state performance of adaptive arrays. The transient response is studied by computing the eigenvalues associated with the signal covariance matrix. The steering vector required to maximize the output SINR of Applebaum-type adaptive arrays in the presence of mutual coupling is also given. 相似文献
878.
879.
T. Aziz S. Ahmad H. Ahrar S. B. Beri V. S. Bhatia S. N. Ganguli S. K. Gupta V. K. Gupta A. Gurtu G. L. Kaul Manjit Kaur A. R. Khan S. Kumar P. K. Malhotra L. K. Mangotra I. S. Mittra Y. Prakash N. K. Rao M. Shafi M. Shyam G. Singh S. K. Tuli Aligharh Collaboration Bombay Collaboration Chandigarh Collaboration Jammu Collaboration Varanasi Collaboration 《Zeitschrift fur Physik C Particles and Fields》1985,27(3):325-328
880.
A vibration analysis of an excitation system supported flexibly on a three layer sandwich beam is presented in this paper. The flexibly supported excitation system, which is essentially the primary system, consists of a mass, a spring and a dash-pot. The beam is analyzed separately as a continuous system in a classical way and then its dynamic stiffness at the junction point is combined with that of the primary system to obtain the resultant dynamic stiffness, which in turn is used to develop the expressions for the response of the primary system and the transmissibility provided by the whole system. Both response and transmissibility are evaluated for different geometrical and physical parameters of the sandwich beam. The solution to this problem is also obtained by approximating the sandwich beam by a lumped mass supported on a spring and dash-pot. The results in the two cases are compared. Results obtained from an experimental test-rig substantiate the theoretical results. 相似文献