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991.
A dual-mode algorithm for routing an unmanned autonomous roving vehicle designed to explore the uncertain terrain of other planets is presented. The algorithm consists of a global mode, which uses dynamic programming and terrain information available from photo reconnaissance data to determine a nominal optimal path, and a local mode, which routes the vehicle around obstacles whose presence, location, and extent are not known in advance. Gaussian probability density functions are used to simulate terrain for examples that illustrate the performance of the algorithm. 相似文献
992.
The use of constant-false-alarm-rate (CFAR) techniques to keep false alarm rates at a suitable low level is reviewed. Radar resource management for clutter suppression, a novel approach for multifunction phased-array radar that can more effectively suppress clutter, is proposed. The results of a simulation study, which indicate the maximum permissible P fa and the improvement of detection performance, demonstrate the effectiveness of resource management, especially when an all-neighbor filter is used 相似文献
993.
N S Manukovsky V S Kovalev I G Rygalov VYeZolotukhin 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》1997,20(10):1827-1832
An experimental model of matter turnover in the biotic cycle: plants (plant biomass) --> mushrooms (residual substrate + mushroom fruit bodies) --> worms (biohumus) --> microorganisms (soillike substrate) --> plants is presented. The initial mass of soillike substrate was produced from wheat plants grown in a hydroponic system. Three cycles of matter turnover in the biotic cycle were carried out. Grain productivity on soillike substrate was 21.87 g/m2 day. The results obtained were used for designing a CES containing man, plants, soillike substrate, bioregeneration module and aquaculture. It was shown, that the circulating dry mass of the CES is 756 kg. The main part (88%) of the circulating mass accumulates in the soillike substrate and bioregeneration module. 相似文献
994.
Ohtomo I. Kumazawa H. Itanami T. Ueno K. Kondo A. Yasaka T. Nakajima K. Kawakami Y. Misawa M. 《IEEE transactions on aerospace and electronic systems》1992,28(4):990-1001
The configuration, on-ground tests, and design verification results for the multibeam antenna flight model for Engineering Test Satellite-VI (ETS-VI) are described for onboard multibeam antennas with thirteen and five beams for the Ka - and S -bands, respectively. The antennas feature Ka -band frequency reuse in alternate beams through use of a cluster horn; shared use of a reflector for two frequency bands using a novel frequency selective surface (FSS); large, lightweight deployable main reflectors with diameters of 3.5 m and 2.5 m; and a highly accurate antenna-pointing control system consisting of RF sensors and an antenna-pointing mechanism to drive the subreflector 相似文献
995.
M Oguchi K Nitta K Ohtsubo Y Tako 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》1994,14(11):237-240
In order to determine a required plant cultivation area which can sustain human life in a closed environment, the material circulating measurement system including a Closed-type Plant Cultivation Equipment (CPCE) in which the metabolic data of plants can be accurately measured has been constructed. According to results from cultivation experiments using rice, the harvest index was 29.9% for 110 days, and the required crop area to supply food, oxygen and water for one person was calculated to be about 111m2, 36m2 and 0.9m2, respectively. 相似文献
996.
A logic-based track formation procedure was presented by C.B. Chang et al. (1984). In addition to the conventional gating logic, it utilized the negative log-likelihood function (goodness of fit or sum of residuals) to further reduce the false track acceptance probability. An analytical technique for the evaluation of the effectiveness of this reduction is presented. The exact solution in closed form and a Gaussian approximation are given and compared. It is shown that the goodness of fit provides an additional reduction of the false track acceptance probability by a factor of two to three 相似文献
997.
Goshen-Meskin D. Bar-Itzhack I.Y. 《IEEE transactions on aerospace and electronic systems》1992,28(4):1068-1075
For pt.I see ibid., vol.28, no.4, p.1056-67, Oct. 1992. The method of analyzing the observability of time-varying linear systems as piecewise constant systems (PWCS) is applied to the analysis of in-flight alignment (IFA) of inertial navigation systems (INS) whose estimability is known to be enhanced by maneuvers. The validity of this approach to the analysis of IFA is proven. The analysis lays the theoretical background to, and clearly demonstrates the observability enhancement of, IFA. The analytic conclusions are confirmed by covariance simulations. Although INS IFA was handled to various degrees in the past, a comprehensive control theoretic approach to the problem is introduced. The analysis yields practical conclusions and a procedure previously unknown 相似文献
998.
Mutational effects of space flight on Zea mays seeds. 总被引:10,自引:0,他引:10
M Mei Y Qiu Y He H Bucker C H Yang 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》1994,14(10):33-39
The growth and development of more than 500 Zea mays seeds flown on LDEF were studied. Somatic mutations, including white-yellow stripes on leaves, dwarfing, change of leaf sheath color or seedling color were observed in plants developed from these seeds. When the frequency of white-yellow formation was used as the endpoint and compared with data from ground based studies, the dose to which maize seeds might be exposed during the flight was estimated to be equivalent to 635 cGy of gamma rays. Seeds from one particular holder gave a high mutation frequency and a wide mutation spectrum. White-yellow stripes on leaves were also found in some of the inbred progenies from plants displayed somatic mutation. Electron microscopy studies showed that the damage of chloroplast development in the white-yellow stripe on leaves was similar between seeds flown on LDEF and that irradiated by accelerated heavy ions on ground. 相似文献
999.
H. Noda T. Terasawa Y. Saito H. Hayakawa A. Matsuoka T. Mukai 《Space Science Reviews》2001,97(1-4):423-426
‘The Japanese Mars probe, NOZOMI, is staying in the interplanetary space (1–1.5 AU) until its Mars’ orbit insertion scheduled
in early 2004. Every 16 months on this interplanetary orbit the spacecraft crosses around 1 AU the ‘gravitational focusing
cone’ of the interstellar helium, which are penetrating into the inner heliosphere under the solar gravity. During the first
crossing of the cone in the season of March–May 2000, we observed these helium particles after the solar wind pickup process
with an E/q type ion detector aboard NOZOMI. We have estimated the original temperature of the interstellar helium as 11 000 K.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
1000.
Fuwen Yang Zidong Wang Hung Y.S. Huisheng Shu 《IEEE transactions on aerospace and electronic systems》2005,41(2):438-448
The mixed H/sub 2//H/sub /spl infin// filtering problem for uncertain linear continuous-time systems with regional pole assignment is considered. The purpose of the problem is to design an uncertainty-independent filter such that, for all admissible parameter uncertainties, the following filtering requirements are simultaneously satisfied: 1) the filtering process is asymptotically stable; 2) the poles of the filtering matrix are located inside a prescribed region that compasses the vertical strips, horizontal strips, disks, or conic sectors; 3) both the H/sub 2/ norm and the H/sub /spl infin// norm on the respective transfer functions are not more than the specified upper bound constraints. We establish a general framework to solve the addressed multiobjective filtering problem completely. In particular, we derive necessary and sufficient conditions for the solvability of the problem in terms of a set of feasible linear matrix inequalities (LMIs). An illustrative example is given to illustrate the design procedures and performances of the proposed method. 相似文献