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R. Sridharan Tirtha Pratim Das S.M. Ahmed Gogulapati Supriya Anil Bhardwaj J.A. Kamalakar 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2013
In the past, clues on the potential radiogenic activity of the lunar interior have been obtained from the isotopic composition of noble gases like Argon. Excess Argon (40) relative to Argon (36), as compared to the solar wind composition, is generally ascribed to the radiogenic activity of the lunar interior. Almost all the previous estimates were based on, ‘on-the-spot’ measurements from the landing sites. Relative concentration of the isotopes of 40Ar and 36Ar along a meridian by the Chandra’s Altitudinal Composition Explorer (CHACE) experiment, on the Moon Impact Probe (MIP) of India’s first mission to Moon, has independently yielded clues on the possible spatial heterogeneity in the radiogenic activity of the lunar interior in addition to providing indicative ‘antiquity’ of the lunar surface along the ground track over the near side of the moon. These results are shown to broadly corroborate the independent topography measurements by the Lunar Laser Ranging Instrument (LLRI) in the main orbiter Chandrayaan-1. The unique combination of these experiments provided high spatial resolution data while indicating the possible close linkages between the lunar interior and the lunar ambience. 相似文献
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With the rapid advancement in remote sensing technology and corresponding applications, the Earth Observation Ground Segment has undergone a significant change at NRSA. From dedicated data acquisition and processing systems, we have realized multi-mission data acquisition quick look and browse systems and also multi-mission integrated information management systems. Front end of data reception station has been upgraded to handle wider bandwidth and data rates up to 320 Mbps for near future missions such as the Radar Imaging Satellite (RISAT). Antenna, feed, down converters and RF chain have been upgraded. To cater to multi-mission scenario mission independent, fully configurable demodulator/bit synchs have been deployed. For handling data acquisition in multi-satellite scenario where in data from 5 to 6 remote sensing satellites are to be received almost simultaneously, automation of operations has been incorporated towards station configuration to avoid manual errors. From media-based data handling, there has been a shift towards net centric data handling among the various work centers such as user order processing, data processing systems, special processing systems, data quality evaluation, and product quality control work centers. The turn around time for dissemination of user desired data products has been improved from two weeks to one day. Presently a state of the art integrated environment has been envisaged which will bring down the turn around time for the supply of data products significantly. Automation has been incorporated at both data acquisition and data processing to improve the product throughput. Presently NRSA is catering to a demand of about 30,000 data products per annum and in the next two years it is aimed to reach a level of 50,000 products per annum by realizing the integrated multi-mission ground system for earth observation (IMGEOS). This will significantly modify the entire data production and dissemination chain so that data can be made available to user within 1 h from data acquisition at Shadnagar in some cases. Some of these novel developments planned in the near future will be discussed in this paper. 相似文献
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Geeta Vichare Ankush Bhaskar Gauri Datar Anil Raghav K.U. Nair C. Selvaraj M. Ananthi A.K. Sinha M. Paranjape T. Gawade C.P. Anil Kumar C. Panneerselvam S. Sathishkumar S. Gurubaran 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2018,61(10):2555-2568
Recently, equatorial secondary cosmic ray observatory has been established at Equatorial Geophysical Research Laboratory (EGRL), Tirunelveli, (Geographic Coordinates: 8.71°N, 77.76°E), to study secondary cosmic rays (SCR) produced due to the interaction of primary cosmic rays with the Earth’s atmosphere. EGRL is a regional center of Indian Institute of Geomagnetism (IIG), located near the equator in the Southern part of India. Two NaI(Tl) scintillation detectors are installed inside the temperature controlled environment. One detector is cylindrical in shape of size 7.62?cm?×?7.62?cm and another one is rectangular cuboid of 10.16?cm?×?10.16?cm?×?40.64?cm size. Besides NaI(Tl) detectors, various other research facilities such as the Geomagnetic observatory, Medium Frequency Radar System, Digital Ionosonde, All-sky airglow imager, Atmospheric electricity laboratory to measure the near-Earth atmospheric electric fields are also available at EGRL. With the accessibility of multi- instrument facilities, the objective is set to understand the relationship between SCR and various atmospheric and ionospheric processes, during space weather and terrestrial events.For gamma-ray spectroscopy, it is important to test the performance of the NaI(Tl) scintillation detectors and to calibrate the gamma-ray spectrum in terms of energy. The present article describes the details of the experimental setup installed near the equator to study cosmic rays, along with the performance testing and calibration of the detectors under various conditions. A systematic shift in the gain is observed with varying temperature of the detector system. It is found that the detector’s response to the variations in the temperature is not just linear or non-linear type, but it depends on the history of the variation, indicating temperature hysteresis effects on NaI detector and PMT system. This signifies the importance of isothermal environment while studying SCR flux using NaI(Tl) detectors, especially for the experiments conducted during daytime such as solar eclipses etc. 相似文献
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Anil KUMAR C.P.GANDHI Hesheng TANG Govind VASHISHTHA Rajesh KUMAR Yuqing ZHOU Jiawei XIANG 《中国航空学报》2022,35(1):250-265
The underlying study investigates single valued neutrosophic entropy based adaptive sensitive frequency band selection for variational mode decomposition(VMD) for the purpose of identifying defective components in an axial pump. The proposed methodology is applied in the following steps. First, VMD is applied for decomposing vibration signals into various frequency bands, called as modes. After computing energy of each VMD, the lower(minimum) and upper(maximum) bounds from these energy readings ... 相似文献
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