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661.
Chikovani V.V. Yatsenko Yu.A. Barabashov A.S. Marusyk P.I. Umakhanov E.O. Taturin V.N. 《Aerospace and Electronic Systems Magazine, IEEE》2009,24(5):40-43
Metallic resonator Q-factor is very sensitive to the resonator's material, its thermal and chemical treatment, design, and environment; i.e., pressure and temperature. In order to obtain higher accuracy for CVG it is necessary to use resonator evacuation. Resonator mass plays a very important role in sensitivity to angle rate, in stability of vibration, in response to environmental condition changes, and also to external vibration and shock resistance. tnnalabs Holding Inc. uses a cylindrical resonator with increased rim thickness of up to 2 mmn and more. This concerns resonator material and design parameters selection, material thermal treatment to increase resonator Q-factor, and improved control algorithms in order to increase metallic CVG accuracy. As a result, CVG bias instability of 0.025 degth and random walk of 0.008 degvh for the resonator diameter 43 mmn, and 0.2 deg/h for the resonator diameter 25 mm were obtained. Future opportunities for Innalabs CVG is also discussed herein. Test results are presented for CVG43 and CVG25. Three-axis CVG unit under control of one DSP "Sharc" and IMU parameters are forecasted. 相似文献
662.
Candamo J. Kasturi R. Goldgof D. Sarkar S. 《IEEE transactions on aerospace and electronic systems》2009,45(3):937-949
A novel thin line detection algorithm for use in low-altitude aerial vehicles is presented. This algorithm is able to detect thin obstacles such as cables, power lines, and wires. The system is intended to be used during urban search and rescue operations, capable of dealing with low-quality images, robust to image clutter, bad weather, and sensor artifacts. The detection process uses motion estimation at the pixel level, combined with edge detection, followed by a windowed Hough transform. The evidence of lines is tracked over time in the resulting parameter spaces using a dynamic line movement model. The algorithm's receiver operating characteristic curve (ROC) is shown, based on a multi-site dataset with 86 videos with 10160 wires spanning in 5576 frames. 相似文献
663.
Today, every modern organization aspires to improve its performance through better use of information technology. As communication technology improves, organizations can operate over wider distances and can even assemble operational components on an ad-hoc basis to meet requirements of a specific objective. Future air traffic communication studies are already discussing whether to operate IP networks that are combining voice and data transport. The problem is that although voice and data are using a common infrastructure, they remain separate at the application level. Probably, some service providers have already enjoyed reduced network infrastructure and operational costs by merging voice and data transport, but the majority may have failed to realize the significant cost, productivity, and service differentiation capabilities that converged, collaborative applications could bring. This elaborates mechanisms needed for a robust and globally interconnected network environment (including infrastructure, systems, processes, and people) in which data is shared timely and seamlessly among users, applications, and platforms. Such an environment enables substantially improved situational awareness and shortened decision-making cycles. Stepping ahead, our contribution discusses standards making application or service convergence a reality. 相似文献
664.
P. P. Pavlov R. S. Litvinenko M. N. Mubarakhin I. O. Yushin V. M. Nigmatullin 《Russian Aeronautics (Iz VUZ)》2008,51(2):198-204
A technique for selecting a rational variant of a multifunctional aircraft system using the analytic hierarchy process is proposed and a solution of a practical problem is presented. 相似文献
665.
T.P. Dachev B. Tomov Yu. Matviichuk Pl. Dimitrov N. Bankov 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2009
The paper presents observation of relativistic electrons. Data are collected by the Radiation Risk Radiometer-Dosimeters (R3D) B2/B3 modifications during the flights of Foton M2/M3 satellites in 2005 and 2007 as well as by the R3DE instrument at the European Technology Exposure Facility (EuTEF) on the Columbus External Payload Adaptor at the International Space Station (ISS) in the period February 20 – April 28, 2008. On the Foton M2/M3 satellites relativistic electrons are observed more frequently than on the ISS because of higher (62.8°) inclination of the orbit. At both Foton satellites the usual duration of the observations are a few minutes long. On the ISS the duration usually is about 1 min or less. The places of observations of high doses due to relativistic electrons are distributed mainly at latitudes above 50° geographic latitude in both hemispheres on Foton M2/M3 satellites. A very high maximum is found in the southern hemisphere at longitudinal range 0°–60°E. At the ISS the maximums are observed between 45° and 52° geographic latitude in both hemispheres mainly at longitudes equatorward from the magnetic poles. The measured absolute maximums of dose rates generated by relativistic electrons are found to be as follows: 304 μGy h−1 behind 1.75 g cm−2 shielding at Foton M2, 2314 μGy h−1 behind 0.71 g cm−2 shielding at Foton M3 and 19,195 μGy h−1 (Flux is 8363 cm−2 s−1) behind les than 0.4 g cm−2 shielding at ISS. 相似文献
666.
Observability Analysis and Active Control for Airborne SLAM 总被引:1,自引:0,他引:1
667.
668.
Lehman D. Clark K. Cook B. Gavit S. Kayali S. McKinney J. Milkovich D. Reh K. Taylor R. Casani J. Griebel T. 《Aerospace and Electronic Systems Magazine, IEEE》2009,24(3):12-21
Congress authorized NASA's Prometheus Project in February 2003, with the first Prometheus mission slated to explore the icy moons of Jupiter. The project had two major objectives: 1) to develop a nuclear reactor that would provide unprecedented levels of power and show that it could be processed safely and operated reliably in space for long-duration, deep-space exploration; and 2) to explore the three icy moons of Jupiter - Callisto, Ganymede, and Europa - and return science data that would meet the scientific goals as set forth in the Decadal Survey Report of the National Academy of Sciences. Early in project planning, it was determined that the development of the Prometheus nuclear-powered spaceship would be complex and require the intellectual knowledge residing at numerous organizations across the country. In addition, because of the complex nature of the project and the multiple partners, approaches beyond those successfully used to manage a typical JPL project would be needed. This describes the key experiences in managing Prometheus, which should prove useful for future projects of similar scope and magnitude. 相似文献
669.
Pressure and Ionization Balances in the Circum-Heliospheric Interstellar Medium and the Local Bubble
Edward B. Jenkins 《Space Science Reviews》2009,143(1-4):205-216
A disconcerting mismatch of thermal pressures for two media in contact with each other, (1) the warm, Circum-Heliospheric Interstellar Medium (CHISM) and (2) the very hot material within a much larger region called the Local Bubble (LB), has troubled astronomers for over two decades. A possible resolution of this problem, at least in part, now seems possible. We now understand that earlier estimates for the average electron density in the very hot LB plasma were inflated by an unrecognized foreground contamination to the low energy diffuse X-ray background measurements. This foreground illumination arises from photons emitted by charge exchange reactions between solar wind ions and neutral atoms from the interstellar medium that enter into the heliosphere. However, with the resolution of this problem comes a new one. The high ionization fraction of helium in the CHISM, relative to that of hydrogen, could be understood in terms of the effects from a strong flux of EUV and X-ray radiation coming from both the Local Bubble and a conductive interface around the CHISM. A revision of this interpretation may now be in order, now that the photoionization rate from radiation emitted by hot gas the Local Bubble is lower than previously assumed. 相似文献
670.
Waveform Design for Multistatic Radar Detection 总被引:1,自引:0,他引:1
We derive the optimal Neyman-Pearson (NP) detector and its performance, and then present a methodology for the design of the transmit signal for a multistatic radar receiver. The detector assumes a Swerling I extended target model as well as signal-dependent noise, i.e., clutter. It is shown that the NP detection performance does not immediately lead to an obvious signal design criterion so that as an alternative, a divergence criterion is proposed for signal design. A simple method for maximizing the divergence, termed the maximum marginal allocation algorithm, is presented and is guaranteed to find the global maximum. The overall approach is a generalization of previous work that determined the optimal detector and transmit signal for a monostatic radar. 相似文献