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971.
Southwest Microwave, Inc. (SMI) introduced the world's first commercially viable bistatic microwave intrusion detection sensor in 1971. Bistatic microwave has become the paradigm for high security perimeters, and SMI products have become industry standards. With the introduction of the Intrepid Digital Microwave, SMI brings the latest in Digital Signal Processing (DSP) and power and data networking to this proven sensor technology 相似文献
972.
973.
Analytical and experimental considerations of the common-mode noise in a dc-to-dc connverterare discussed. Analyzing the mechanism of the common-mode noise generation by means of a high-frequency equivalent circuit, we estimate the output noise voltage generated during the transistor's turn-on time. This commonmode noise consists mainly of two frequency components distributed in several megahertz. The effects of parasitic parameters on the noise voltage and frequencies are clarified. In addition, the effect of a common-mode choke on the noise suppression is discussed experimentally. 相似文献
974.
K. Bullough 《Space Science Reviews》1983,35(2):175-183
In-situ spectral observations of power-line harmonic radiation (PLHR) are still quite rare and almost all the detailed characteristics have been derived from studies at Antarctic stations such as Siple and Halley, and their conjugates in North America. Because of the lack of more direct satellite evidence of PLHR and the difficulties in interpretation of morphological studies, such as those of Ariel 3 and 4, there is considerable controversy concerning the relative importance of PLHR and its contribution to wave-particle interactions (WPI) in the magnetosphere. The early Ariel 3 and 4 global surveys indicated that, in terms of true mean wave energy, there is no longitudinal localisation, the contribution of world-wide intense VLF emissions, associated with magnetic storms, being dominant. Also, the most intense wave emission, that of plasmaspheric hiss at ELF (< 1 kHz) exhibits little evidence of localisation. The PLHR phenomenon is most conspicuous by its persistence in quiet times (Kp ≤ 2+) at 45° < Λ < 55° over North America and its conjugate region, even though the less frequent strongest emissions, to which it gives rise in the summer, are located polewards at 3 < L < 5. In the northern winter, when spheric activity over both North America and its conjugate are low, there is a high occurrence of strong discrete emissions, which are more sharply localised than in the summer, on the NE industrial U.S.A. field line. The most recent Ariel 4 studies, particularly on the spheric wavefield over North America (using data from the Appleton Laboratory impulse counters) and on the character of the wavefield over the mainland and over the Atlantic immediately to the east (where the spheric contribution is similar) throw new light on the problem. It appears that the principal role of the PLHR may be to sustain duct structure and multihop propagation which is relatively much rarer over the Atlantic. Typical industrial PLHR consists of a series of narrow pulses at twice the mains frequency. It is suggested that these ‘artificial spherics’ may help to sustain the WPI and multihop duct structure. At L = 4, Yoshida et al. (1980) have shown that there is a strong, sharp maximum for WPIs originating in spherics, at f ? 3 kHz, in good agreement with Siple observations. 相似文献
975.
V. Tamilarasan S.K. Sharma S.R. Nagabhushana 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》1983,3(2):287-290
An experiment was undertaken to select the optimum spectral bands for the discrimination of land use/cover for proposed Indian Remote Sensing Satellite. A feature selection method was used for the discrimination analysis on the multiband data collected by Bendix 11-channel Modular Multiband Scanner over Tirupati test site of Chittoor district, Andhra Pradesh, South India. Of the various combinations of bands analysed, the optimum combination of four bands was defined as that one which provided the greatest divergence distances to discriminate the specific land covers in the test sites. On the basis of the above studies the optimum bands so chosen are 0.49–0.54 μm, 0.62–0.66 μm, 0.66–0.70 μm and 0.77–0.86 μm. 相似文献
976.
K. Sezaki S. Enya M. Morioka J. Ochiai I. Tanasawa T. Maekawa 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》1983,3(5):85-88
In this paper, the Marangoni convection including buoyancy convection in two-dimensional fluid model was investigated experimentally and theoretically. The transparent liquid in the test cell was heated and cooled under various conditions. The fluid flow driven by surface tension and by buoyancy force was visualized and measured. The flow patterns, velocity distributions and temperature field were obtained and they were compared with the results of the numerical solutions. The effect of the configuration and the convection in microgravity on crystal growth was discussed. The temperature field of the crystallizing surface was predicted. 相似文献
977.
A new open-loop adaptive-array system with excellent transient behavior is presented. The system is constructed of analog circuits and determines complex weights without using the feedback of the array output. The performance attainable with the system is described in detail. It is shown that the convergence rate of the system does not depend on a noise environment but is determined by the time constant of the low-pass filters included. Moreover, it is shown that although the steady-state performance is quite good when the interference sources differ widely in signal strength, the steady-state performance can be far below optimum when two or more interference sources are present at roughly equal power levels. 相似文献
978.
Ramachandra K.V. Division R.C. 《IEEE transactions on aerospace and electronic systems》1983,(5):776-778
Analytical results are presented for determining the steady-state components of the gain and error covariance matrices of the two-state Kalman tracking filter with white noise maneuver capability. 相似文献
979.
980.