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891.
Diane Sonya Wong Ryan Chornock Alexei V. Filippenko 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2006,38(12):2813-2815
We present results of optical follow-up observations of candidate ultra-luminous X-ray sources (ULXs). Using Keck optical spectroscopy, 17 of the candidates from the Colbert and Ptak [Colbert, E.J.M., Ptak, A.F. A catalog of candidate intermediate-luminosity X-ray objects. ApJS 143, 25–45, 2002] catalog have been identified; this is one of the largest sets of optical identifications of such objects thus far. Fifteen are background active galactic nuclei (AGN); two are foreground stars in our Galaxy. These findings are consistent with background and foreground object expectations, as derived from log N–log S relations. Also, the results are briefly discussed in terms of the spiral-galaxy/ULX connection. 相似文献
892.
893.
A V Shafirkin V M Petrov 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2002,30(4):995-998
This paper presents a new concept of radiation hazard assessment for spacecraft crew members during long term space missions on the basis of a generalized dosimetric function. This new dosimetric function enables a complicated nature of space radiation exposure to be reduced to the conditions of a standard irradiation. It can be obtained on the basis of mean-tissue equivalent dose values calculated for each space radiation source and transmission coefficients describing the influence of the complex spatial and temporal distribution of the absorbed dose in the cosmonaut's body on the radiobiological effects. The combination of cosmic ionizing radiation with other non-radiation nature factors in flight can also be accounted for. In terms of the generalized dose, it is possible to assess the nature and extent of lowering a crew working capacity, as well as radiation risk, both during a flight and post flight period. 相似文献
894.
J.R. Cecatto H.S. Sawant F.C.R. Fernandes V. Krishan J.A.C.F. Neri J.C. Moraes Filho 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2003,32(12):2533-2537
Type-III bursts are signatures of the electron beams accelerated during the solar flares, their observation and investigation provide information of the acceleration processes, the characteristics of the exciting agent and the acceleration site. The Brazilian Solar Spectroscope (BSS), in operation at INPE, Brazil, have recorded type-III radio bursts in decimetric range (2050–2250 MHz) with high time resolution of 20 ms. Decimetric reverse drift bursts are possibly generated in a dense loop by electron beams travelling towards the photosphere. Hence their time profiles should carry signatures of the density inhomogenities in the loop. Here the temporal and spectral characteristics of decimetric type-III bursts are presented. 相似文献
895.
Defense radar research and development in Australia is today largely, but not exclusively, confined within Australia's Defense Science and Technology Organization, DSTO, and its R&D collaborators in universities. Radar has a long history in Australia, dating back to World War II links with British defense radar development, and radar R&D continues to be an important focus within DSTO. It is impossible, in the context of a brief conference paper, to give other than the broadest-brush picture of Australian radar development over a half-century or more. So the approach taken is necessarily highly selective and focuses specifically on several illustrative development projects, in an attempt to convey the flavor of national radar research priorities, the way they drive R&D and likely future directions. Despite the escalating requirement for a national skills base in defense radar and allied technologies, there are currently legitimate concerns about the robustness of this base. Recruitment of high-caliber researchers into the field of radar and management of radar research careers are issues currently presenting major challenges. A number of initiatives are in place linking DSTO with university research; a recent effort to enhance the stature and visibility of radar research in Australia is the establishment of the Centre of Expertise in Microwave Radar as a joint venture between DSTO and Adelaide University. 相似文献
896.
N A Tikhomirova S A Ushakova N P Kovaleva I V Gribovskaya A A Tikhomirov 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2005,35(9):1589-1593
Use of halophytes (salt-tolerant vegetation), in a particular vegetable Salicornia europaea plants which are capable of utilizing NaCl in rather high concentrations, is one of possible means of NaCl incorporation into mass exchange of bioregenerative life support systems. In preliminary experiments it was shown that S. europaea plants, basically, could grow on urine pretreated with physicochemical processing and urease-enzyme decomposing of urea with the subsequent ammonia distillation. But at the same time inhibition of the growth process of the plants was observed. The purpose of the given work was to find out the influence of excessive quantities of some mineral elements contained in products of physicochemical processing of urine on the production process and NaCl accumulation by S. europaea plants. As the content of mineral salts in the human liquid wastes (urine) changed within certain limits, two variants of experimental solutions were examined. In the first variant, the concentration of mineral salts was equivalent to the minimum salt content in the urine and was: K - 1.5 g/l, P - 0.5 g/l, S - 0.5 g/l, Mg - 0.07 g/l, Ca - 0.2 g/l. In the second experimental variant, the content of mineral salts corresponded to the maximum salt content in urine and was the following: K - 3.0 g/l, P - 0.7 g/l, S - 1.2 g/l, Mg - 0.2 g/l, Ca - 0.97 g/l. As the control, the Tokarev nutrient solution containing nitrogen in the form of a urea, and the Knop nutrient solution with nitrogen in the nitrate form were used. N quantity in all four variants made up 177 mg/l. Air temperature was 24 degrees C, illumination was continuous. Light intensity was 690 micromoles/m2s of photosynthetically active radiation. NaCl concentration in solutions was 1%. Our researches showed that the dry aboveground biomass of an average plant of the first variant practically did not differ from the control and totaled 11 g. In the second variant, S. europaea productivity decreased and the dry aboveground biomass of an average plant totaled 8 g. The increase of K quantity in the experimental solutions resulted in an elevated content of the element in the plants. The increase of K uptake in the second experimental variant was accompanied by a 30-50% decrease of Na content in comparison with the other variants. Comparative Na content in the other variants was practically identical. N, Mg and P content in the control and experimental variants was also practically identical. The increase of S quantity in the second experimental variant also increased S uptake by the plants. But Ca quantity, accumulated in aboveground plants biomass in the experimental variants was lower than in the control. NaCl uptake by plants, depending on the concentration of mineral salts in the experimental solutions, ranged from 8 g (maximum salt content) up to 15 g (minimum salt content) on a plant growth area that totaled 0.032 m2. Thus, high concentrations of mineral salts simulating the content of mineral salts contained in urine did not result in a significant decrease of S. europaea productivity. The present work also considers the influence of higher light intensity concentrations on productivity and NaCl accumulation by S. europaea plants grown on experimental solutions with high salt content. 相似文献
897.
I. Yu. Skriabysheva 《Cosmic Research》2005,43(6):432-441
The main problems concerning the electric polarization of low-orbit spacecraft are considered, including the results of studying the structure of the Earth's upper ionosphere, the methods of calculating the electrophysical characteristics of construction materials for spacecraft, and the elaboration of recommendations to mitigate the negative effects due to processes of charging and discharging. 相似文献
898.
Examples of solar microwave precursors and estimates of their energetic characteristics are discussed based on spectral investigations of the preflare activity. 相似文献
899.
V. I. Badin Yu. V. Dumin 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》1995,15(12):119-122
The initial reduction of the electron density after the injection explosion is shown to be associated with recombination at the adiabatic cooling under the cloud expansion. Primordial thermal ions can disappear in triple collisions almost entirely. Nevertheless, a minor amount of ions is conserved due to the freezing effect. The further rapid increase in the electron concentration may be attributed to the secondary ionization process. It is shown that the cumulative electronic ionization can account for the observed electron density elevation. The modified two-stream instability can provide a longitudinal (anomalous) resistance for the longitudinal electric field required for an avalanche. The electric field and longitudinal currents arise owing to the polarization with ions entrained by the neutral gas across the magnetic field and magnetized electrons moving along the field. 相似文献
900.
D L Bubenheim K Wignarajah 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》1997,20(10):2029-2035
The goal of resource recovery in a regenerative life support system is maintenance of product quality to sure support of reliable and predictable levels of life support function performance by the crop plant component. Further, these systems must be maintained over extended periods of time, requiring maintenance of nutrient solutions to avoid toxicity and deficiencies. The focus of this study was to determine the suitability of the ash product following incineration of inedible biomass as a source of inorganic nutrients for hydroponic crop production. Inedible wheat biomass was incinerated and ash quality characterized. The incinerator ash was dissolved in adequate nitric acid to establish a consistent nitrogen concentration is all nutrient solution treatments. Four experimental nutrient treatments were included: control, ash only, ash supplemented to match the control treatment, and ash only quality formulated with reagent grade chemicals. When nutrient solutions were formulated using only ash following incineration of inedible biomass, a balance in solution is established representing elemental retention following incineration and nutrient proportions present in the original biomass. The resulting solution is not identical to the control. This imbalance resulted in a suppression of crop growth. When the ash is supplemented with reagent grade chemicals to establish the same balance as in the control--growth is identical to the control. The ash appears to carry no phytotoxic materials. Growth in solution formulated with reagent grade chemicals but matching the quality of the ash only treatment resulted in similar growth to that of the ash only treatment. The ash product resulting from incineration of inedible biomass appears to be a suitable form for recycle of inorganic nutrients to crop production. 相似文献