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131.
O.A. Maltseva O.S. Poltavsky 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2009
The aim of this paper is to investigate various aspects of the International Reference Ionosphere (IRI) performance in European area and to evaluate its accuracy and efficiency for: long term prediction of the critical frequencies foF2 and the maximum usable frequencies (MUF); using storm-time correction option (ST); the total electron content (TEC) and the maximum observable frequency (MOF) updating. Data of foF2, TEC, MOF are related to 2005. It is obtained that median values of foF2 can be predicted with the mean error σ(med)∼ 0.49 MHz. For median values of MUF absolute σ was 1.39 MHz and relative σr was 8.8%. For instanteneous values estimates are increased to 1.58σ(med) MHz for foF2 and could reach 3.84 MHz for MUF. Using correction ST-option and TEC values provided ∼30% improvement but TEC seems to be more preferable. However, from considered parameters of the IRI updating (ST-factor, TEC, MOF) the best results were demonstrated by MOF. Using the IRI2007 to calculate TEC gives 20–50% improvement of TEC correspondence to experimental values but this improvement is not enough to treat TEC without the IRI model adaptation. 相似文献
132.
S. Ushakova A. Tikhomirov V. Shikhov Yu. Kudenko O. Anischenko J.-B. Gros Ch. Lasseur 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2009
The purpose of this work was to study the full-scale potential use of human mineralized waste (feces and urine) as a source of mineral elements for plant cultivation in a biological life support system (BLSS). Plants that are potential candidates for a photosynthesizing link were grown on a neutral solution containing human mineralized waste. Spring wheat Triticum aestivum L., peas Pisum sativum L. Ambrosia cultivar and leaf lettuce Lactuca sativa L., Vitaminny variety, were used. The plants were grown hydroponically on expanded clay aggregates in a vegetation chamber in constant environmental conditions. During plant growth, a determined amount of human mineralized waste was added daily to the nutrient solution. The nutrient solution remained unchanged throughout the vegetation period. Estimated plant requirements for macro-elements were based on a total biological productivity of 0.04 kg day−1 m−2. As the plant requirements for potassium exceeded the potassium content of human waste, a water extract of wheat straw containing the required amount of potassium was added to the nutrient solution. The Knop’s solution was used in the control experiments. 相似文献
133.
A.L. Mishev J.N. Stamenov I.I. Angelov N.O. Ahababian I.N. Kirov E.S. Malamova 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2009
We review the main activities carried out at Moussala peak (2925 m above sea level, 42°11′N, 23°35′E) station in Bulgaria, connected with cosmic ray investigations during the last five decades. Several important results obtained at the station are reported. The detector design and corresponding methodological studies of the presently operational devices are shown as well, precisely the Cherenkov light telescope, lead free neutron monitor and muon telescope. The scientific potential of the existing complex is discussed. 相似文献
134.
135.
Hespanha J.M. Yakimenko O.A. Kaminer I.I. Pascoal A.M. 《IEEE transactions on aerospace and electronic systems》2004,40(3):889-902
This paper addresses the problem of nonlinear filter design to estimate the relative position and velocity of an unmanned air vehicle (UAV) with respect to a point on a ship using infrared (IR) vision, inertial, and air data sensors. Sufficient conditions are derived for the existence of a particular type of complementary filters with guaranteed stability and performance in the presence of so-called out-of-frame events that arise when the vision system loses its target temporarily. The results obtained build upon new developments in the theory of linear parametrically varying systems (LPVs) with brief instabilities - also reported in the paper - and provide the proper framework to deal with out-of-frame events. Field tests with a prototype UAV illustrate the performance of the filter and the scope of applications of the new theory developed. 相似文献
136.
E.B. Romanova O.M. Pirog N.M. Polekh A.V. Tashchilin G.A. Zherebtsov J.K. Shi X. Wang 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2008,41(4):569-578
The results of modeling of ionospheric disturbances observed in the East Asian region during moderate storms are presented. The numerical model for ionosphere–plasmasphere coupling developed at the ISTP SB RAS is used to interpret the data of observations at ionospheric stations located in the longitudinal sector of 90–130°E at latitudes from auroral zone to equator. There is obtained a reasonable agreement between measurements and modeling results for winter and equinox. In the summer ionosphere, at the background of high ionization by the solar EUV radiation in the quiet geomagnetic period the meridional thermospheric wind strongly impacts the electron concentration in the middle and auroral ionosphere. The consistent calculations of the thermospheric wind permit to obtain the model results which are closer to summer observations. The actual information about the space-time variations of thermosphere and magnetosphere parameters should be taken into account during storms. 相似文献
137.
M Belli F Ianzini O Sapora M A Tabocchini F Cera R Cherubini A M Haque G Moschini P Tiveron G Simone 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》1996,18(1-2):73-82
Low energy protons and other densely ionizing light ions are known to have RBE>1 for cellular end points relevant for stochastic and deterministic effects. The occurrence of a close relationship between them and induction of DNA dsb is still a matter of debate. We studied the production of DNA dsb in V79 cells irradiated with low energy protons having LET values ranging from 11 to 31 keV/micrometer, i.e. in the energy range characteristic of the Bragg peak, using the sedimentation technique. We found that the initial yield of dsb is quite insensitive to proton LET and not significantly higher than that observed with X-rays, in agreement with recent data on V79 cells irradiated with alpha particles of various LET up to 120 keV/micrometer. By contrast, RBE for cell inactivation and for mutation induction rises with the proton LET. In experiments aimed at evaluating the rejoining of dsb after proton irradiation we found that the amount of dsb left unrepaired after 120 min incubation is higher for protons than for sparsely ionizing radiation. These results indicate that dsb are not homogeneous with respect to repair and give support to the hypothesis that increasing LET leads to an increase in the complexity of DNA lesions with a consequent decrease in their repairability. 相似文献
138.
O A Kuznetsov C S Brown H G Levine W C Piastuch M M Sanwo-Lewandowski K H Hasenstein 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2001,28(4):651-658
The effect of spaceflight on starch development in soybean (Glycine max L., BRIC-03) and potato (Solanum tuberosum, Astroculture-05) was compared with ground controls by biophysical and biochemical measurements. Starch grains from plants from both flights were on average 20-50% smaller in diameter than ground controls. The ratio delta X/delta rho (delta X --difference of magnetic susceptibilities, delta rho--difference of densities between starch and water) of starch grains was ca. 15% and 4% higher for space-grown soybean cotyledons and potato tubers, respectively, than in corresponding ground controls. Since the densities of particles were similar for all samples (1.36 to 1.38 g/cm3), the observed difference in delta X/delta rho was due to different magnetic susceptibilities and indicates modified composition of starch grains. In starch preparations from soybean cotyledons (BRIC-03) subjected to controlled enzymatic degradation with alpha-amylase for 24 hours, 77 +/- 6% of the starch from the flight cotyledons was degraded compared to 58 +/- 12% in ground controls. The amylose content in starch was also higher in space-grown tissues. The good correlation between the amylose content and delta X/delta rho suggests, that the magnetic susceptibility of starch grains is related to their amylose content. Since the seedlings from the BRIC-03 experiment showed elevated post-flight ethylene levels, material from another flight experiment (GENEX) which had normal levels of ethylene was examined and showed no difference to ground controls in size distribution, density, delta X/delta rho and amylose content. Therefore the role of ethylene appears to be more important for changes in starch metabolism than microgravity. 相似文献
139.
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
140.
A.V. Agapitov O.K. CheremnykhA.S. Parnowski 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2008,41(10):1682-1687
We investigate the generation of ballooning perturbations in the inner magnetosphere of the Earth in the dipole model of the geomagnetic field taking into account ionospheric boundary conditions. The ionosphere is considered as a thin layer with finite conductivity. The eigenmode spectrum is discrete and consists of Alfvén, slow magnetosonic, flute and incompressible modes. Their interaction depends on ionospheric conductivity. The decay rate is small in noon and night sectors and large in dawn and dusk sectors. The lowest stability threshold α/γ ≈ 4.25 is determined by flute modes. 相似文献