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991.
M. M. ROCHE 《New Zealand geographer》1993,49(2):23-31
Abstract. Internationalisation is used as a device with which to reexamine geographies of national development and geography in national development in New Zealand. The second half of the paper discusses national and internationalised forestry in New Zealand before considering some of the new possibilities confronting geographers as the New Zealand economy becomes increasingly internationalised. 相似文献
992.
V. N. Tsytovich R. Bingham U. de Angelis D. A. Bryant C. M. C. Nairn 《Solar physics》1993,147(2):329-335
The possibility of accelerated protons in solar flares having a sharp change in their spectral index is discussed. The analysis is based on the Tsytovich (1982, 1984, 1987a, b, c) acceleration model by MHD turbulence, which is shown to have different resonant conditions for non-relativistic and relativistic particles. The different resonant condition is shown to result in a sharp change in the accelerated proton spectral index, even in the absence of any peculiarity in the spectra of the MHD turbulence. Time scales for accelerated protons to relativistic energies are also derived, and shown to be consistent with observations. We also show that the threshold energy for electron acceleration by low frequency MHD turbulence is much greater than for proton acceleration. The turbulence therefore preferentially accelerates protons. 相似文献
993.
M. Ya. Marov A. V. Kolesnichenko K. K. Manuilov V. P. Osipov 《Solar System Research》2010,44(5):393-402
The methodology and the main features of the Thermophob experiment developed for the direct analysis of the thermophysical
properties of the surface of the Martian satellite Phobos from the Phobos-Grunt lander are considered. The methodical and engineering aspects of the measurements are discussed, and the design of the instrument
and the potential of the interpretation of the measurement results with accounting for the theoretical estimates and the data
of the laboratory tests are discussed. 相似文献
994.
995.
K. L. Mahanta 《Astrophysics and Space Science》2014,350(2):683-689
We have constructed Locally Rotationally Symmetric Bianchi type I (LRSBI) cosmological models in the f(R,T) theory of gravity when the source of gravitation is the bulk viscous fluid. The models are constructed for f(R,T)=R+2f(T) and f(R,T)=f 1(R)+f 2(T). We found that in the first case the model degenerates into effective stiff fluid model of the universe. In the second case we obtained degenerate effective stiff fluid model as well as general bulk viscous models of the universe. Some physical and kinematical properties of the models are also discussed. 相似文献
996.
997.
998.
Tumbling asteroids 总被引:1,自引:0,他引:1
P. Pravec A.W. Harris P. Kušnirák C.W. Hergenrother M.D. Hicks Yu.N. Krugly M.C. Nolan M. Kaasalainen P. Brown J.V. Lambert S. Foglia 《Icarus》2005,173(1):108-131
We present both a review of earlier data and new results on non-principal axis rotators (tumblers) among asteroids. Among new tumblers found, the best data we have are for 2002 TD60, 2000 WL107, and (54789) 2001 MZ7—each of them shows a lightcurve with two frequencies (full terms with linear combinations of the two frequencies are present in the lightcurve). For 2002 TD60, we have constructed a physical model of the NPA rotation. Other recent objects which have been found to be likely tumblers based on their lightcurves that do not fit with a single periodicity are 2002 NY40, (16067) 1999 RH27, and (5645) 1990 SP. We have done a statistical analysis of the present sample of the population of NPA rotators. It appears that most asteroids larger than ∼0.4 km with estimated damping timescales (Harris, 1994, Icarus 107, 209) of 4.5 byr and longer are NPA rotators. The statistic of two short-period tumblers (D=0.04 and 0.4 km) with non-zero tensile strength suggests that for them the quantity μQ/T, where μ is the mechanical rigidity, Q is the elastic dissipation factor, and T is a spin excitation age (i.e., a time elapsed since the last significant spin excitation event), is greater by two to four orders of magnitude than the larger, likely rubble-pile tumblers. Among observational conditions and selection effects affecting detections of NPA rotations, there is a bias against detection of low-amplitude (small elongation) tumblers. 相似文献
999.
1000.
L. F. Chernogor 《Kinematics and Physics of Celestial Bodies》2018,34(3):134-146
Statistical characteristics of meteoroids with kinetic energy from 0.1 to 440 kt TNT are estimated based on NASA satellite observations made in 1994–2016. The distributions of the number of falling meteoroids are constructed and analyzed based on the values of their initial kinetic energy, initial velocity, initial mass, altitude, geographic coordinates of the maximum total radiated energy region, and the year of the fall. Correlation dependences “mass–initial kinetic energy,” “maximum total radiated energy region altitude–initial kinetic energy,” and “maximum total radiated energy region altitude–initial velocity (the square of the initial velocity)” are constructed. 相似文献