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701.
I I Gitelson A A Tikhomirov O V Parshina S A Ushakova G S Kalacheva 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2003,31(7):1781-1786
The effect of elevated temperatures of 35 and 45 degrees C (at the intensities of photosynthetically active radiation 322, 690 and 1104 micromoles m-2 s-1) on the photosynthesis, respiration, and qualitative and quantitative composition of the volatiles emitted by wheat (Triticum aestuvi L., cultivar 232) crops was investigated in growth chambers. Identification and quantification of more than 20 volatile compounds (terpenoids--alpha-pinene, delta 3 carene, limonene, benzene, alpha- and trans-caryophyllene, alpha- and gamma-terpinene, their derivatives, aromatic hydrocarbons, etc.) were conducted by gas chromatograph/mass spectrometry. Under light intensity of 1104 micromoles m-2 s-1 heat resistance of photosynthesis and respiration increased at 35 degrees C and decreased at 45 degrees C. The action of elevated temperatures brought about variations in the rate and direction of the synthesis of volatile metabolites. The emission of volatile compounds was the greatest under a reduced irradiation of 322 micromoles m-2 s-1 and the smallest under 1104 micromoles m-2 s-1 at 35 degrees C. During the repair period, the contents and proportions of volatile compounds were different from their initial values, too. The degree of disruption and the following recovery of the functional state depended on the light intensity during the exposure to elevated temperatures. The investigation of the atmosphere of the growth chamber without plants has revealed the substances that were definitely technogenic in origin: tetramethylurea, dimethylsulfide, dibutylsulfide, dibutylphthalate, and a number of components of furan and silane nature. 相似文献
702.
G. V. Kasatkin 《Cosmic Research》2005,43(6):395-403
The problem of studying a ring in the gravitational field of a center arose after the discovery of Saturn's rings by Galileo and subsequent discovery of the rings of other planets of the Solar System. Modern theoretical investigations of the existence and stability of planetary rings are mostly related to studies of plane differentially rotating discs [1]. As opposed to this line of research, this paper follows the approach established in classical works [2–4]. 相似文献
703.
V. A. Sadovnichiy A. M. Amelyushkin V. Angelopoulos V. V. Bengin V. V. Bogomolov G. K. Garipov E. S. Gorbovskoy B. Grossan P. A. Klimov B. A. Khrenov J. Lee V. M. Lipunov G. W. Na M. I. Panasyuk I. H. Park V. L. Petrov C. T. Russell S. I. Svertilov E. A. Sigaeva G. F. Smoot Yu. Shprits N. N. Vedenkin I. V. Yashin 《Cosmic Research》2013,51(6):427-433
At present, the Institute of Nuclear Physics of Moscow State University, in cooperation with other organizations, is preparing space experiments onboard the Lomonosov satellite. The main goal of this mission is to study extreme astrophysical phenomena such as cosmic gamma-ray bursts and ultra-high-energy cosmic rays. These phenomena are associated with the processes occurring in the early universe in very distant astrophysical objects, therefore, they can provide information on the first stages of the evolution of the universe. This paper considers the main characteristics of the scientific equipment aboard the Lomonosov satellite. 相似文献
704.
705.
Robert A. Goehlich Jay K. AndersonNathan N. Harrold Joseph A. BemisMike T. Nettleingham Joshua M. CobinBradley R. Zimmerman Ben L. AvniMichael D. Gonyea Nicholas Y. Ilchena 《Space Policy》2013
This article sheds light on the key player needed for any space tourism adventure: the pilot who flies the spacecraft. The paper addresses the potential benefits of including a pilot at the controls when designing a space tourism spacecraft. It examines the basic qualifications and advanced skills required of space tourism pilots and discusses key training requirements for selected pilots and space pilots' pay and benefits. In addition, the research concludes that, just as the pioneers of passenger transport in aviation entertained and captured the interest of their passengers, the space pilot should have the skills of a tour guide. 相似文献
706.
Coronal holes are the coolest and darkest regions of the upper solar atmosphere, as observed both on the solar disk and above the solar limb. Coronal holes are associated with rapidly expanding open magnetic fields and the acceleration of the high-speed solar wind. During the years of the solar minima, coronal holes are generally confined to the Sun??s polar regions, while at solar maxima they can also be found at lower latitudes. Waves, observed via remote sensing and detected in-situ in the wind streams, are most likely responsible for the wind and several theoretical models describe the role of MHD waves in the acceleration of the fast solar wind. This paper reviews the observational evidences of detection of propagating waves in these regions. The characteristics of the waves, like periodicities, amplitude, speed provide input parameters and also act as constraints on theoretical models of coronal heating and solar wind acceleration. 相似文献
707.
Harry Y. McSween Jr. David W. Mittlefehldt Andrew W. Beck Rhiannon G. Mayne Timothy J. McCoy 《Space Science Reviews》2011,163(1-4):141-174
Howardite-eucrite-diogenite (HED) meteorites, thought to be derived from 4 Vesta, provide the best sampling available for any differentiated asteroid. However, deviations in oxygen isotopic composition from a common mass-fractionation line suggest that a few eucrite-like meteorites are from other bodies, or that Vesta was not completely homogenized during differentiation. The petrology and geochemistry of HEDs provide insights into igneous processes that produced a crust composed of basalts, gabbros, and ultramafic cumulate rocks. Although most HED magmas were fractionated, it is unresolved whether some eucrites may have been primary melts. The geochemistry of HEDs indicates that bulk Vesta is depleted in volatile elements and is relatively reduced, but has chondritic refractory element abundances. The compositions of HEDs may favor a magma ocean model, but inconsistencies remain. Geochronology indicates that Vesta accreted and differentiated within the first several million years of solar system history, that magmatism continued over a span of ??10 Myr, and that its thermal history extended for perhaps 100 Myr. The protracted cooling history is probably responsible for thermal metamorphism of most HEDs. Impact chronology indicates that Vesta experienced many significant collisions, including during the late heavy bombardment. The age of the huge south pole crater is controversial, but it probably ejected Vestoids and many HEDs. Continued impacts produced a regolith composed of eucrite and diogenite fragments containing only minor exotic materials. HED meteorites serve as ground truth for orbital spectroscopic and chemical analyses by the Dawn spacecraft, and their properties are critical for instrument calibration and interpretation of Vesta??s geologic history. 相似文献
708.
In this paper, calculations of some thermo-hydraulic parameters of different intensified channels have been carried out and a grooved channel that is optimal in mass and energy expenditure is determined. A new variant of the intensified channel is proposed and recommendations for engineers are presented. 相似文献
709.
Ovshinsky S.R. Dhar S.K. Fetcenko M.A. Corrigan D.A. Reichman B. Young K. Fierro C. Venkatesan S. Gifford P. Koch J. 《Aerospace and Electronic Systems Magazine, IEEE》1999,14(5):17-23
While Ovonic NiMH batteries are already in high volume commercial production for portable applications, advances in materials technology have enabled performance improvements in specific energy (100 Wh/kg), specific power (600-1000 W/kg), high temperature operation, charge retention, and voltage stability. Concurrent with technology advances, Ovonic NiMH batteries have established performance and commercial milestones in electric vehicles, hybrid electric vehicles, as well as scooter, motorcycle and bicycle applications. As important as these advances, significant manufacturing cost reductions have also occurred which allow continued growth of NiMH technology. In this paper, advances in performance, applications and cost reduction are discussed with particular emphasis on the improved proprietary metal hydride and nickel hydroxide materials that make such advances possible 相似文献
710.
Castella F.R. Dunnebacke F.G. 《IEEE transactions on aerospace and electronic systems》1974,(6):891-895
A two-dimensional x, y Kalman tracking filter is analyzed for a track-while-scan (TWS) operation when the radar sensor measures range and bearing (r, ?) at uniform sampling intervals T seconds apart. This development explicitly considers the coupling between the quantities measured by the sensor (r, ?) and the Cartesian x, y coordinate system selected for the tracking operation. The steadystate components of the gain and error covariance matrixes are analytically determined under the assumption of a white noise maneuver acceleration model in two dimensions. These results are verified by computer calculation of the Kalman filter matrix equations. 相似文献