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排序方式: 共有2385条查询结果,搜索用时 156 毫秒
1.
Albul V. I. Bychkov V. B. Gusev K. E. Demidov V. S. Demidova E. V. Kurchanov A. F. Luk'yashin V. E. Sokolov A. Yu. 《Measurement Techniques》2003,46(8):810-814
A monitor is proposed based on ultrasonic production when ionizing radiation passes through a medium. The recording element is a 0.2 mm aluminum plate mounted in a ceramic acoustic converter AC in the form of a wedge of thickness 2 mm. The low plate thickness minimizes the beam parameter distortion, while special technology used in the AC provides high sensitivity. The device has been calibrated in the proton beam from the ITEP accelerator at 200 MeV with 2·109–6·1010 particles in a pulse and a pulse length of 70 nsec. 相似文献
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The kinetics of electronic processes in vidicon phototargets based on semiconductor-insulator structures with a narrow-gap semiconductor is considered taking into account charge drain in the insulator layer and relaxation of the nonequilibrium depletion region in the semiconductor layer. The integration time, threshold sensitivity, and resolution at various intensities of incident radiation are estimated. 相似文献
7.
Artem Sokolov Darrell Whitley Andre’ da Motta Salles Barreto 《Genetic Programming and Evolvable Machines》2007,8(3):221-237
This paper evaluates different forms of rank-based selection that are used with genetic algorithms and genetic programming.
Many types of rank based selection have exactly the same expected value in terms of the sampling rate allocated to each member
of the population. However, the variance associated with that sampling rate can vary depending on how selection is implemented.
We examine two forms of tournament selection and compare these to linear rank-based selection using an explicit formula. Because
selective pressure has a direct impact on population diversity, we also examine the interaction between selective pressure
and different mutation strategies. 相似文献
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D. Dietrich ÖVE H. Reiter Th. Sauter H. -J. Schweinzer 《e & i Elektrotechnik und Informationstechnik》1997,114(5):225-230
The past decade may be regarded as the phase of the fundamental developments in fieldbus systems that were based on the OSI model. Today we are entering a second stage. It is the objective of this issue to present the current state and where the further developments will lead to. This introductory article is intended to give an overview on the subject. 相似文献
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M. Muhr ÖVE S. Pack ÖVE H. Haidvogl F. Kreyca 《e & i Elektrotechnik und Informationstechnik》1997,114(11):680-686
Recently appeared defects on high voltage cables have required an urgent evaluation of the impact of lightning strikes necessary. In some cases overvoltages between the copper wire screen of the cable and earth may appear which cause damages of the cablesheath. Field measurements with a classification of the voltage impulses at the copper wire screen have been made to evaluate the number of events. Additionally a numerical model was developed to study the effects of atmospheric discharges on underground cables with emphasis to the influence on the cablesheath. This numeric method was also applied to estimate the effectiveness of different protection arrangements. This contribution presents evaluation methods for overvoltages of cables and a model used firstly for calculating the stress caused by differential voltages and secondly to determinate the influence of protection measures. 相似文献
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The mechanical properties of totally ischemic hearts of inbred albino rats were studied. The ischemic myocardium was found to be more sensitive to cyclic loads. Energy deficient contracture of cardiomyocytes is a factor which increases the resistance of the myocardium to mechanical effects. 相似文献