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111.
Y.B. Acharya A. Jayaraman B.H. Subbaraya 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》1985,5(1):65-68
A balloon borne multichannel photometer for measurement of atmospheric scattering in the near ultraviolet and the visible wavelength regions has been developed at the Physical Research Laboratory, Ahmedabad for study of the size distribution and number density of aerosols at tropospheric and lower stratospheric altitudes. The instrumentation involves tracking the sun in elevation and scanning in azimuth. The payload was recently flown on a 100 kg. balloon from the Hyderabad Balloon Facility on 18 April 1984. The balloon reached a float altitude of 35 km and good quality data has been obtained from an altitude of 6 km upto float altitude. Data analysis is still in progress. The present paper details the instrument design and presents a few illustrations of the instrument performance from this flight. 相似文献
112.
Detection of satellite attitude sensor faults using the UKF 总被引:4,自引:0,他引:4
Xiong K. Chan C.W. Zhang H.Y. 《IEEE transactions on aerospace and electronic systems》2007,43(2):480-491
A novel fault detection (FD) method for nonlinear systems using the residuals generated by the unscented Kalman filter (UKF) is proposed. The errors of the UKF are derived and sufficient conditions for the convergence of the UKF are presented. As the local approach is a powerful statistical technique for detecting changes in the mean of a Gaussian process, it is used to devise a hypothesis test to detect faults from residuals obtained from the UKF. Further, it is demonstrated that the selection of a sample number is important in improving the performance of the local approach. To illustrate the implementation and performance of the proposed technique, it is applied to detect sensor faults in the measurement of satellite attitude. 相似文献
113.
M Casolino V Bidoli E De Grandis M P De Pascale G Furano A Morselli L Narici P Picozza E Reali R Sparvoli A Galper M Korotkov Y Ozerov A Popov G Mazzenga M Ricci G Castellini S Avdeev M Boezio W Bonvicini A Vacchi N Zampa P Spillantini P Carlson C Fuglesang 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2003,31(1):135-140
In this work we present preliminary results of nuclear composition measurements on board space station MIR obtained with SILEYE-2 particle telescope. SILEYE-2 was placed on MIR in 1997 and has been working since then. It consists of an array of 6 active silicon strip detectors which allow nuclear and energetic identification of cosmic rays in the energy range between approximately 30 and 200 MeV/n. The device is attached to an helmet and connected to an eye mask which shields the cosmonaut eyes from light and allow studies of the Light Flashes (LF) phenomenon. In addition to the study of the causes of LF, the device is used to perform real time long term radiation environment monitoring inside the MIR, performing measurements in solar quiet and active days. 相似文献
114.
It is generally accepted that the energy that drives coronal mass ejections (CMEs) is magnetic in origin. Sheared and twisted
coronal fields can store free magnetic energy which ultimately is released in the CME. We explore the possibility of the specific
magnetic configuration of a magnetic flux rope of field lines that twist about an axial field line. The flux rope model predicts
coronal observables, including heating along forward or inverse S-shaped, or sigmoid, topological surfaces. Therefore, studying
the observed evolution of such sigmoids prior to, during, and after the CME gives us crucial insight into the physics of coronal
storage and release of magnetic energy. In particular, we consider (1) soft-X-ray sigmoids, both transient and persistent;
(2) The formation of a current sheet and cusp-shaped post-flare loops below the CME; (3) Reappearance of sigmoids after CMEs;
(4) Partially erupting filaments; (5) Magnetic cloud observations of filament material. 相似文献
115.
F J Burns Y Jin S J Garte S Hosselet 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》1994,14(10):507-519
In the multistage theory of carcinogenesis, cells progress to cancer through a series of discrete, irreversible, heritable genetic alterations or mutations. However data on radiation-induced cancer incidence in rat skin suggests that some part of an intermediate repairable alteration may occur. Data are presented on cancer induction in rat skin exposed to the following radiations: 1. an electron beam (LET=0.34 keV/um, 2. a neon ion beam (LET=25 keV/um and 3. an argon ion beam (LET=125 keV/um. The latter 2 beams were generated by the Bevalac at the Lawrence Berkeley Laboratory, Berkeley, CA. About 6.0 cm2 of skin was irradiated per rat. The rats were observed every 6 weeks for at least 78 weeks and tumors were scored at first occurrence. Several histological types of cancer, including squamous and basal cell carcinomas, were induced. The cancer yield versus radiation dose was fitted by the quadratic equation (Y(D)=CLD+BD2), and the parameters C and B were estimated for each type of radiation. Analysis of the DNA from the electron-induced carcinomas indicated that K-ras and/or c-myc oncogenes were activated in all tumors tested, although only a small proportion of neon-induced tumors showed similar activation. In situ hybridization indicated that the cancers contain subpopulations of cells with differing amounts of c-myc and H-ras amplification. The results are consistent with the idea that ionizing radiation produces carcinogenically relevant lesions via 2 repairable events at low LET and via a non-repairable, linked event pathway at high LET; either pathway may advance the cell by 1 stage in the multistage model. The model, if validated, permits the direct calculation of cancer risk in rat skin in a way that can be subjected to experimental testing. 相似文献
116.
Y. Lin S.F. Martin O. Engvold L.H.M. Rouppe van der Voort M. van Noort 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2008
High resolution Hα images and magnetograms (0.2 arc s) of an active region were obtained in alternating time series at 42 s cadences using the Swedish 1-m Solar Telescope on 2004 August 21. The Hα filtergrams reveal an active region filament and surges consisting of thread-like structures which have widths similar to the widths of chromospheric fibrils, both recorded down to the resolution limit in the best images. All observed structures in the active region appear highly dynamic. Fibrils show counterstreaming strongly resembling the counterstreaming threads in filaments. 相似文献
117.
Y. Tanaka 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》1985,5(3):81-89
Tenma, the second X-ray astronomy satellite of Japan launched in February 1983, is outlined. The main instrument of Tenma is a large-area gas scintillation proportional counter array. Some of the highlights of the results thus far obtained are briefly discussed. 相似文献
118.
V Switzer RC rdBogo G A Mickley 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》1994,14(10):443-451
Application of the degeneration sensitive, cupric-silver staining method to brain sections of male Sprague-Dawley rats irradiated 4 days before sacrifice with 155 Mev protons, 2-8 Gy at 1 Gy/min (N=6) or 22-l0lGy at 20 Gy/min (N=16) or with 18.6 Mev electrons, 32-67 Gy at 20 Gy/min (N=20), doses which elicit behavioral changes (accelerod or conditioned taste aversion), resulted in a display of degeneration of astrocyte-like cell profiles which were not uniformly distributed. Plots of 'degeneration scores' (counts of profiles in 29 areas) vs. dose for the proton and electron irradiations displayed a linear dose response for protons in the range of 2-8 Gy. In the 20-100 Gy range, for both electrons and protons the points were distributed in a broad band suggesting a saturation curve. The dose range in which these astrocyte-like profiles becomes maximal corresponds well with the dose range for the X-ray eradication of a subtype of astrocytes, 'beta astrocytes'. 相似文献
119.
S. Namazov S. Nikolaishvili Y. Romanovsky V. Ivanov 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》1995,15(12):123-126
The evolution of a barium ion cloud formed in the MR-20 rocket experiment in the low-latitude ionosphere is considered using data of Doppler multifrequency sounding. 相似文献
120.
An analysis of the relationship between a linear amplifier chain and an analog-to-digital converter (ADC) in a digital microwave receiver, with respect to sensitivity and dynamic range issues, is presented. The effects of gain, third-order intermodulation products and ADC characteristics on the performance of the receiver are illustrated and design criteria for the linear amplifier chain (given a specified ADC) are developed. A computer program is included which calculates theoretical receiver performance based on gain and third-order intermodulation product selections. Experimental results are also presented and compared with theoretical values 相似文献