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991.
A. V. Streltsov J.-J. Berthelier A. A. Chernyshov V. L. Frolov F. Honary M. J. Kosch R. P. McCoy E. V. Mishin M. T. Rietveld 《Space Science Reviews》2018,214(8):118
Active ionospheric experiments using high-power, high-frequency transmitters, “heaters”, to study plasma processes in the ionosphere and magnetosphere continue to provide new insights into understanding plasma and geophysical proceses. This review describes the heating facilities, past and present, and discusses scientific results from these facilities and associated space missions. Phenomena that have been observed with these facilities are reviewed along with theoretical explanations that have been proposed or are commonly accepted. Gaps or uncertainties in understanding of heating-initiated phenomena are discussed together with proposed science questions to be addressed in the future. Suggestions for improvements and additions to existing facilities are presented including important satellite missions which are necessary to answer the outstanding questions in this field. 相似文献
992.
A. N. Sabirzyanov A. I. Glazunov A. N. Kirillova K. S. Titov 《Russian Aeronautics (Iz VUZ)》2018,61(2):257-264
Multiparameter studies of the discharge coefficient dependence on the nozzle geometry and the presence of a condensed phase in combustion products were performed. The simulation results obtained satisfactorily agree with the well-known generalized data. The modern computational fluid dynamics methods were shown to be able to refine the generalized empirical relations. 相似文献
993.
David P. O’Brien Andre Izidoro Seth A. Jacobson Sean N. Raymond David C. Rubie 《Space Science Reviews》2018,214(1):47
The planetary building blocks that formed in the terrestrial planet region were likely very dry, yet water is comparatively abundant on Earth. Here we review the various mechanisms proposed for the origin of water on the terrestrial planets. Various in-situ mechanisms have been suggested, which allow for the incorporation of water into the local planetesimals in the terrestrial planet region or into the planets themselves from local sources, although all of those mechanisms have difficulties. Comets have also been proposed as a source, although there may be problems fitting isotopic constraints, and the delivery efficiency is very low, such that it may be difficult to deliver even a single Earth ocean of water this way. The most promising route for water delivery is the accretion of material from beyond the snow line, similar to carbonaceous chondrites, that is scattered into the terrestrial planet region as the planets are growing. Two main scenarios are discussed in detail. First is the classical scenario in which the giant planets begin roughly in their final locations and the disk of planetesimals and embryos in the terrestrial planet region extends all the way into the outer asteroid belt region. Second is the Grand Tack scenario, where early inward and outward migration of the giant planets implants material from beyond the snow line into the asteroid belt and terrestrial planet region, where it can be accreted by the growing planets. Sufficient water is delivered to the terrestrial planets in both scenarios. While the Grand Tack scenario provides a better fit to most constraints, namely the small mass of Mars, planets may form too fast in the nominal case discussed here. This discrepancy may be reduced as a wider range of initial conditions is explored. Finally, we discuss several more recent models that may have important implications for water delivery to the terrestrial planets. 相似文献
994.
Mohamed Khalil Ben-Larbi Kattia Flores Pozo Tom Haylok Mirue Choi Benjamin Grzesik Andreas Haas Dominik Krupke Harald Konstanski Volker Schaus Sándor P. Fekete Christian Schurig Enrico Stoll 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2021,67(11):3598-3619
995.
996.
F. Di Capua L. Campajola P. Casolaro M. Campajola A. Aloisio A. Lucaroni G. Furano A. Menicucci S. Di Mascio F. Malatesta M. Ottavi 《Advances in Space Research (includes Cospar's Information Bulletin, Space Research Today)》2019,63(10):3249-3257
A new methodology for Total Ionizing Dose (TID) tests is proposed. It is based on the employment of an on-chip 90Sr/90Y beta source as alternative to standard methods such as 60Co gamma rays and electrons from LINAC. The use of a compact beta source for TID tests has several advantages. In particular, the irradiation of devices with more than one radiation source results in a better representation of the complex space radiation environment composed of several types, energies and dose-rates. In addition, the use of an easy handling beta source allows the irradiation of electronic devices without any damage to other auxiliary circuit. In this work, 90Sr/90Y beta source dosimetry and related radiation field characteristics are discussed in depth.In order to validate the proposed source for TID tests, a rather complex device such as the “SPC56EL70L5” microcontroller from ST-Microelectronics was exposed to 90Sr/90Y beta rays. The results of this test were compared to that of a previous test of another sample from the same lot with a standard gamma 60Co source. The electronic performances following the two irradiations have been found to be in excellent agreement, by demonstrating therefore the validity of the proposed beta source for TID tests. 相似文献
997.
Steady-state flow of viscous lubrication fluid in the nonsymmetrical clearance between two out-of-line cylinders of the bearing unit in the aircraft electric motor is discussed. An analytical solution of the task based on application of the perturbation theory is presented. 相似文献
998.
Cosmic Research - We have considered procedure and results of the experimental study for spectral characteristics of self emission from laboratory models of electric thrusters with closed electron... 相似文献
999.
This paper presents a theoretically and practically grounded architecture of design methods combination. A possibility and completeness of developing integral design solutions and intensifying the design process are provided by redistribution of emphases of numerical and natural experiments. 相似文献
1000.
The sensitivity of observed data to an unknown parameter is enhanced by utilizing optimal inputs. The derivation is given for the optimal input of an nth-order nonlinear differential equation. To obtain the optimal input, the solution of 4n two-point boundary value equations is required. Numerical resutis are given for a second order linear example. The optimal return is compared with the return obtained for a step input. The existence of a critical time length is demonstrated. 相似文献