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排序方式: 共有98条查询结果,搜索用时 187 毫秒
61.
Huang Rui Malik Arunima Lenzen Manfred Jin Yutong Wang Yafei Faturay Futu Zhu Zhiyi 《Natural Hazards》2022,110(3):2227-2248
Natural Hazards - With the development of interregional trade, a potential disaster that happens in one place could cause enormous economic losses in distant areas. Timely and comprehensive... 相似文献
62.
Dian Fiantis Malik Nelson Eric Van Ranst Jusop Shamshuddin Nikolla P. Qafoku 《山地科学学报》2009,6(3):240-254
The Java Island, Indonesia with abundant amount of pyroclastic deposits is located in the very active and dynamic Pacific Ring of Fires. Studying the geochemical weathering indices of these pyroclastic deposits is important to get a clear picture about weathering profiles on deposits resulting from the eruption of Mt. Merapi. Immediately after the first phase of the eruption (March to June 2006), moist and leached pyroclastic deposits were collected. These pyroclastic deposits were found to be composed of volcanic glass, plagioclase feldspar in various propoitions, orthopyroxene, clinopyroxene, olivine, amphibole and titanomagnetite. The total elemental composition of the bulk samples (including trace elements and heavy metals) was determined by wet chemical methods and X-ray fluorescence (XRF) analyses. Weathering of the pyroelastic deposits was studied using various weathering indices. The Ruxton ratio, weathering index of Parker, Vought resudual index and chemical index of weathering of moist pyroclastic deposits were lower than those of the leached samples, but the alteration indices (chemical and plagioclase) were slightly higher in the moist compared to the leached pyroelastic deposits. 相似文献
63.
We discuss the range of validity of solutions of the Schrödinger equation with a temperaturemodified Coulomb potential. Such a potential, as was recently pointed out, may be relevant to the resolution of the long-standing problem of unidentified solar emission lines. We also consider in detail a predictive test of our approach, and draw attention to some related conceptual issues. 相似文献
64.
Theoretical and Applied Climatology - This study investigates the spatial and temporal patterns of trends and magnitude of rainfall on monthly, seasonal and annual time scales of 13 districts of... 相似文献
65.
The evolution of two dimensional wave packets on the surface of a self-gravitating fluid layer is investigated and shown to be governed by a nonlinear Schrödinger equation. The wave train of finite amplitude is modulationally unstable. Obtained also are the dynamical equations for the second harmonic resonance. The analysis reveals that the general motion consists of both amplitude and phase modulated waves of which the pure phase and amplitude modulated waves, solitary waves, and phase jump are just the special cases. 相似文献
66.
Stewart W.I. Chu D. Malik S. Lerner S. Singh H. 《Oceanic Engineering, IEEE Journal of》1994,19(4):599-610
Bathymetry and backscatter measurements from a 120-kHz phase-difference sonar are analysed in terms of statistical and spectral characteristics. Data from a multisensor, multiscale survey of the Juan de Fuca Ridge are compared across three distinct geological provinces: sediment pond, ridge flank, and axial valley. The detrended bathymetry follows a Gaussian distribution; the power spectral density can be approximately described by a power law. The composite multiscale power spectrum demonstrates a similar slope spanning a spatial frequency range from about 0.005 to 50 cycles/m, corresponding to a range of geological features from a few hundred meters down to several centimeters. The backscattering strength and grazing-angle dependencies agree with previous empirical studies; data from a sediment-pond region are shown to match theoretical predictions of the composite-roughness model. Histograms of the echo amplitude are characterized by a multimodal Rayleigh probability density function. For all analyses, the data show distinct differences among the three provinces 相似文献
67.
Relativistic flows both in stellar interior and stellar atmospheres are obviously in action, hence, their treatment is of interest. The present communication aims at deriving by a different method the general equations that govern such flows.The derivation is based merely on the first two principles of thermodynamics and the inertia-energy equivalence principles; while the end results are the formulation of the energy tensor and the energy-flux and momentum equations. The assumptions of ideal flow and adiabatic behaviour of the medium adopted here are restrictive. 相似文献
68.
69.
Ananth Krishna N. S. Gopinath N. S. Hegde N. K. Malik 《Journal of Earth System Science》2005,114(6):739-748
The Chandrayaan-1 mission proposes to put a 550 kg lunarcraft into Geostationary Transfer Orbit (GTO) using the Polar Satellite
Launch Vehicle (PSLV) which will subsequently be transferred into a 100 km circular lunar polar orbit for imaging purposes.
In this paper, we describe certain aspects of mission strategies which will allow optimum power generation and imaging of
the lunar surface.
The lunar orbit considered is circular and polar and therefore nearly perpendicular to the ecliptic plane. Unlike an Earth
orbiting remote sensing satellite, the orbit plane of lunar orbiter is inertially fixed as a consequence of the very small
oblateness of the Moon. The Earth rotates around the Sun once a year, resulting in an apparent motion of Sun around this orbit
in a year. Two extreme situations can be identified concerning the solar illumination of the lunar orbit, noon/midnight orbit,
where the Sun vector is parallel to the spacecraft orbit plane and dawn/dusk orbit, where the Sun vector is perpendicular
to the spacecraft orbit plane. This scenario directly affects the solar panel configuration. In case the solar panels are
not canted, during the noon/midnight orbit, 100% power is generated, whereas during the dawn/dusk orbit, zero power is generated.
Hence for optimum power generation, canting of the panels is essential. Detailed analysis was carried out to fix optimum canting
and also determine a strategy to maintain optimum power generation throughout the year. The analysis led to the strategy of
180‡ yaw rotation at noon/midnight orbits and flipping the solar panel by 180‡ at dawn/dusk orbits. This also resulted in
the negative pitch face of the lunarcraft to be an anti-sun panel, which is very useful for thermal design, and further to
meet cooling requirements of the spectrometers.
In principle the Moon’s surface can be imaged in 28 days, because the orbit chosen and the payload swath provide adequate
overlap. However, in reality it is not possible to complete the imaging in 28 days due to various mission constraints like
maximum duration of imaging allowed keeping in view the SSR sizing and payloads data input rate, time required for downlinking
the payload data, data compression requirements and visibility of the lunarcraft for the Bangalore DSN. In each cycle, all
the latitudes are swept. Due to the constraints mentioned, only 60‡ latitude arc coverage is possible in each orbit. As Bangalore
DSN is the only station, half of the orbits in a day are not available. The longitudinal gaps because of non-visibility are
covered in the next cycle by Bangalore DSN. Hence, in the firstprime imaging season, only 25% of the prime imaging zones are covered, and an additional threeprime imaging seasons are required for a full coverage of the Moon in two years. Strategy is also planned to cover X-ray payload coverage considering
swath and orbit shift. 相似文献
70.
The causes of the failure of various dams, the existing approaches to determining the parameters of flood waves caused by dam failures, and the authors' method of calculation of these waves are considered. Characterization of the consequences of the dam-failure flood wave in the tailwater pool of the Volgograd hydroelectric station and some unfavorable aspects of possible evacuation of the Saratov reservoir are presented. 相似文献