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791.
A smart system that uses state-of-the-art image processing techniques to detect and track targets moving in video or infrared imagery is presented. It is a general-purpose system that was developed to be independent of the application and the user interface. TCATS has successfully demonstrated a high detection capability and the ability to ignore exterior environmental conditions, such as cloud shadows moving through the scene, snow, blowing dust, rain and moderate camera motion. TCATS can handle many targets and retain the identity of each object from one frame to the next. Special rugged hardware has been developed to reduce the size, cost, and power consumption and to increase the processing rate, reliability, and environmental operating capability of the system. TCATS can be incorporated into an existing video assessment system without a major cost outlay intruder. The TCATS algorithms, custom-developed hardware, and preliminary field test results are described 相似文献
792.
Oli P.V.S. Nagarajan N. Rayan H.R. 《IEEE transactions on aerospace and electronic systems》1993,29(3):696-705
The concept of meridian orbits is briefly reviewed. It is shown that, if a satellite in the meridian orbit makes an odd number (>1) of revolutions per day, then the satellite passes over the same set of meridians twice a day. Satellites in such orbits pass over the same portion of the sky twice a day and every day. This enables a user to adopt a programmed mode of tracking, thereby avoiding a computational facility for orbit prediction, look angle generation, and auto tracking. A constellation of 38 or more satellites placed in a 1200-km altitude circular orbit is favorable for global communications due to various factors. It is shown that appropriate phasing in right ascension of the ascending node and mean anomaly results in a constellation wherein each satellite appears over the user's horizon one satellite after another. Visibility and coverage plots are provided to verify the continuous coverage 相似文献
793.
Chistopher H.A. Gilman S. Hamlen R.P. 《Aerospace and Electronic Systems Magazine, IEEE》1993,8(5):7-10
The current status and thrust of the US Army Research Laboratory's battery and fuel cell R&D programs that support emerging electronic battlefield equipment applications are reviewed. Major technical barriers are identified along with the approaches proposed to solve these anticipated problems 相似文献
794.
When structures made of composite materials are designed to be used in load bearing applications, a primary consideration is the evaluation of their load carrying capacity in compression. To this end, a vast number of research investigations, whose main objective is linked to ascertaining the compressive strength of a composite structure has been carried out and/or is currently being performed. Apart from its practical significance, the complexity associated with the task of predicting compression strength is the main reason for the overt attention this problem is receiving. One such difficulty has been associated with testing. When laboratory tests are carried out to determine compression strength, structural instabilities dictated by the geometry of the structure may interfere with material strength dictated by the mechanical properties of the constituents and their alignment and geometry (needed to describe the microstructure of the material). In addition stress concentrations may occur at undesirable locations. In Part I, issues pertaining to compression testing and micromechanical failure theories are reviewed. 相似文献
795.
796.
A hierarchical control architecture for telerobotic vehicles intended to yield a modular, flexible, and easily expanded control system is presented. This architecture is proposed for applications where simple teleoperation is required, but where additional capabilities might be quickly added without major changes to the control system. Similarities to the NASREM architecture are noted. Results for the hardware implementation of the control system on a telerobotic vehicle, RAYBOT, are given 相似文献
797.
S. I. Avdyushin M. B. Belotserkovsky V. Kim A. S. Koroteev A. M. Kulikov A. I. Livshits Yu. K. Melnikov R. I. Moisya N. N. Petrov H. A. Popov Yu. A. Romanovsky Yu. A. Utkin V. V. Chilap 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》1992,12(12):163-167
Results of rocket experiments on study of plasma flows (PF) artificially injected by sources separated from vehicles and their effect on medium parameters in ionosphere at altitudes 160:230 km are presented.PF were injected comprising lithium ions with velocities 1,2 x 104 m/sec. and cesium-potassium ions with velocities (1,4–1,5)x103 m/sec. Mass flow rate in case of lithium PS is 2 mg/sec, and in case of cesium-potassium PS is 0,2 g/sec. During experiments mass-spectrometer measurements of ion medium content in ranges of different ion masses were held, disturbancies of electric fields with frequencies up to 20 kHz and electron flows with energies 0,7keV, 4,6keV and over 40 keV were controlled at distancies from 150m to (500–600)m between plasma source and scientific equipment. 相似文献
798.
Narayanan R.M. Doerr D.W. Rundquist D.C. 《IEEE transactions on aerospace and electronic systems》1992,28(2):404-412
The temporal decorrelation characteristics of X -band radar backscatter from wind-influenced vegetation were investigated using a short-range CW radar. Radar reflectance data were gathered on various types of individual trees from a distance of approximately 30 m. The windspeed was monitored during each measurement, which lasted 5 s. The crown cover and the mean leaf area of the trees were also recorded. Autocovariance plots were generated for each measurement, from which the decorrelation time was estimated. As expected, the return signals decorrelated faster at higher wind speeds. However, the decorrelation time was also found to depend on the tree type, tree structure, and leaf cover characteristics. Measured decorrelation times for moderate winds (7-9 m/s) were often between 40-60 ms, although the lowest decorrelation time measured under these conditions was 14 ms for the Eastern Cottonwood. In lighter winds (1-4 m/s), decorrelation times were much longer, and there was substantial spread in the data 相似文献
799.
Sanchez-Reillo R. Mengibar-Pozo L. Sanchez-Avila C. 《Aerospace and Electronic Systems Magazine, IEEE》2003,18(3):22-24
Due to the great increase in Information Technology (IT) systems where user authentication is needed, security in those systems relies on using PINs or passwords. During recent years, the scientific community has been trying to improve biometric techniques to be accepted as an alternative to other user authentication schemes. One of the sectors where user identity must be verified, is the identification cards sector. In fact, if great security wants to be achieved, smart cards should be used. But cardholder verification is performed using Card Holder Verification Keys (CHV-Keys), which are PIN-based. The authors are trying to integrate fingerprint verification inside a smart card, following their works in the past. The fingerprint scheme used is shown, and the work to achieve the integration inside a commercial smart card is detailed. 相似文献
800.