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141.
Secondary radioactive isotopes that are used for the determination of cosmic-ray age have relatively short decay lifetimes.
The measured abundance of these isotopes at low energies is representative of the cosmic-ray diffusion and the gas distribution
in a region of a few hundred parsecs around the Sun. We show how to determine the local cosmic-ray diffusion coefficient in
the Galaxy using the data on decaying cosmic-ray nuclei. Calculated surviving fractions of decaying secondary isotopes in
diffusion and leaky box models are presented.
This revised version was published online in June 2006 with corrections to the Cover Date. 相似文献
142.
A. I. Eriksson R. Boström R. Gill L. Åhlén S.-E. Jansson J.-E. Wahlund M. André A. Mälkki J. A. Holtet B. Lybekk A. Pedersen L. G. Blomberg 《Space Science Reviews》2007,128(1-4):729-744
The Rosetta dual Langmuir probe instrument, LAP, utilizes the multiple powers of a pair of spherical Langmuir probes for measurements
of basic plasma parameters with the aim of providing detailed knowledge of the outgassing, ionization, and subsequent plasma
processes around the Rosetta target comet. The fundamental plasma properties to be studied are the plasma density, the electron
temperature, and the plasma flow velocity. However, study of electric fields up to 8 kHz, plasma density fluctuations, spacecraft
potential, integrated UV flux, and dust impacts is also possible. LAP is fully integrated in the Rosetta Plasma Consortium
(RPC), the instruments of which together provide a comprehensive characterization of the cometary plasma.
The LAP Team is listed in Table III. 相似文献
143.
The acquisition of survey knowledge for local and global landmark configurations under time pressure
Sascha Credé Tyler Thrash Christoph Hölscher Sara Irina Fabrikant 《Spatial Cognition & Computation》2019,19(3):190-219
The influence of stress states on cognition is widely recognized. However, the manner in which stress affects survey knowledge acquisition is still unresolved. For the present study, we investigated whether survey knowledge acquisition during a stressful task (i.e., under time pressure) is more accurate for the mental representation of global or local landmarks. Participants navigated through virtual cities with a navigation aid and explicit learning instructions for different landmark configurations. Participants’ judgments of relative direction (JRDs) suggest that global landmark configurations were not represented more accurately than local landmark configurations and that survey knowledge acquisition was not impaired under time pressure. In contrast to prior findings, our results indicate the limitations of the utility of global landmarks for spatial knowledge acquisition. 相似文献
144.
Naomi Murdoch David Mimoun Raphael F. Garcia William Rapin Taichi Kawamura Philippe Lognonné Don Banfield W. Bruce Banerdt 《Space Science Reviews》2017,211(1-4):429-455
The SEIS (Seismic Experiment for Interior Structures) instrument onboard the InSight mission to Mars is the critical instrument for determining the interior structure of Mars, the current level of tectonic activity and the meteorite flux. Meeting the performance requirements of the SEIS instrument is vital to successfully achieve these mission objectives. Here we analyse in-situ wind measurements from previous Mars space missions to understand the wind environment that we are likely to encounter on Mars, and then we use an elastic ground deformation model to evaluate the mechanical noise contributions on the SEIS instrument due to the interaction between the Martian winds and the InSight lander. Lander mechanical noise maps that will be used to select the best deployment site for SEIS once the InSight lander arrives on Mars are also presented. We find the lander mechanical noise may be a detectable signal on the InSight seismometers. However, for the baseline SEIS deployment position, the noise is expected to be below the total noise requirement \(>97~\%\) of the time and is, therefore, not expected to endanger the InSight mission objectives. 相似文献
145.
This chapter gives a brief review on the theory of gamma-ray bursts (GRBs), including the models of multi-messengers (e.g., prompt multiwavelength electromagnetic emissions, high-energy neutrinos, ultra-high-energy cosmic rays, and gravitational waves) and central engines (in particular, mergers of binary neutron stars for short GRBs). For detailed reviews, please see (Piran in Phys. Rep. 314:575, 1999; Rev. Mod. Phys. 76:1143, 2004; Mészáros in Annu. Rev. Astron. Astrophys. 40:137, 2002; Rep. Prog. Phys. 69:2259, 2006; Zhang and Mészáros in Int. J. Mod. Phys. A 19:2385, 2004; Zhang in Chin. J. Astron. Astrophys. 7:1, 2007; Nakar in Phys. Rep. 442:166, 2007; Kumar and Zhang in Phys. Rep. 561:1, 2015). 相似文献
146.
Sources of Ion Outflow in the High Latitude Ionosphere 总被引:4,自引:0,他引:4
Ion composition observations from polar-orbiting satellites in the past three decades have revealed and confirmed the occurrence of a variety of ion outflow processes in the high-latitude ionosphere. These processes constitute a dominant source of ionospheric plasma to the Earth's magnetosphere. We review the current state of our observational knowledge on their occurrence, energy, composition, variability, interrelationships, and quantitative contributions to the overall mass input to the magnetosphere. In addition, we identify the prevalent sources and the gaps of our current understanding of these sources. 相似文献
147.
掺混型碳化硅纤维微波吸收剂的制备 总被引:5,自引:0,他引:5
运用功率超声将平均粒径30nm的超细金属铁粉均匀分散到聚碳硅烷中,通过熔融纺丝,不熔化处理,烧结,制备出具有良好力学性能,电阻率连续可调的掺混弄烨奔走陶瓷纤维。 相似文献
148.
P. S. Thé L. Matveyenko J. Kleczek L. M. Gindilis G. M. Rudnitskij J. Arbocz J. Schuve J. A. Steketee W. de Graaff K. A. van der Hucht Wayne G. Roberge G. Kockarts R. H. van Gent E. Dekker T. S. van Albada D. de Hoop H. Nieuwenhuijzen Josip Kleczek J. L. van Ingen P. Hellings A. Achterberg 《Space Science Reviews》1985,41(1-2):201-213
149.
Kleczek J. van Gent R. H. Rutten Robert J. de Munck J. C. Slottje C. Severne G. Pecker Jean-Claude Postma H. Grishchuk L. P. Niewenhuijzen H. Schuiling R. D. van Beek H. F. Reijnen G. C. M. Heidmann Jean Lemaire J. Bleeker Johan Icke V. Neéman Y. Feast M. W. de Graaff W. 《Space Science Reviews》1986,43(3-4):383-396
Space Science Reviews - 相似文献
150.
B. Van der Holst S. Poedts E. Chané C. Jacobs G. Dubey D. Kimpe 《Space Science Reviews》2005,121(1-4):91-104
Simulations of coronal mass ejections (CMEs) evolving in the interplanetary (IP) space from the Sun up to 1 AU are performed
in the framework of ideal magnetohydrodynamics (MHD) by the means of a finite-volume, explicit solver. The aim is to quantify
the effect of the background solar wind and of the CME initiation parameters, such as the initial magnetic polarity, on the
evolution and on the geo-effectiveness of CMEs. First, three different solar wind models are reconstructed using the same
numerical grid and the same numerical scheme. Then, different CME initiation models are considered: Magnetic foot point shearing
and magnetic flux emergence. For the fast CME evolution studies, a very simple CME model is considered: A high-density and
high-pressure magnetized plasma blob is superposed on a background steady state solar wind model with an initial velocity
and launch direction. The simulations show that the initial magnetic polarity substantially affects the IP evolution of the
CMEs influencing the propagation velocity, the shape, the trajectory (and thus, the geo-effectiveness). 相似文献