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41.
We have studied the stability of location of various equilibrium points of a passive micron size particle in the field of
radiating binary stellar system within the framework of circular restricted three body problem. Influence of radial radiation
pressure and Poynting-Robertson drag (PR-drag) on the equilibrium points and their stability in the binary stellar systems
RW-Monocerotis and Krüger-60 has been studied. It is shown that both collinear and off axis equilibrium points are linearly unstable for increasing value
of β
1 (ratio of radiation to gravitational force of the massive component) in presence of PR-drag for the binary systems. Further
we find that out of plane equilibrium points (L
i
, i=6,7) may exists for range of values of β
1>1 for these binary systems in the presence of PR-drag. Our linear stability analysis shows that the motion near the equilibrium
points L
6,7 of the binary systems is unstable both in the absence and presence of PR-drag. 相似文献
42.
In this work, we have simulated orbits of a particle moving in gravitational field of the Sun-Jupiter system. The effect of
solar radiation pressure, including Poynting Robertson drag, on the evolution of particle orbits in phase space have been
studied for different values of the parameter β
1 (the ratio of radiation to gravitational force) and initial conditions. Characteristics of various computed trajectories
have been studied using wavelet transform (WT), Fourier transform (FT) and Poincare surface of section method. We use wavelet
analysis to identify transitions of a trajectory in time-frequency plane and further apply it to classify it as regular or
chaotic in phase space. Unlike the Fourier transform method (FT), we observe that the wavelet transform (WT) also provides
a basis to identify ‘sticky’ trajectories in the present dynamical system. 相似文献
43.
M. C. Ramadevi S. Seetha Dipankar Bhattacharya B. T. Ravishankar N. Sitaramamurthy G. Meena M. Ramakrishna Sharma Ravi Kulkarni V. Chandra Babu Kumar Brajpal Singh Anand Jain Reena Yadav S. Vaishali B. N. Ashoka Anil Agarwal K. Balaji G. Nagesh Manoj Kumar Dhruti Ranjan Gaan Prashanth Kulshresta Pankaj Agarwal Mathew Sebastian A. Rajarajan D. Radhika Anuj Nandi V. Girish Vivek Kumar Agarwal Ankur Kushwaha Nirmal Kumar Iyer 《Experimental Astronomy》2017,44(1):11-23
Scanning Sky Monitor (SSM) onboard AstroSat is an Xray sky monitor in the soft X-ray band designed with a large field of view to detect and locate transient X-ray sources and alert the astronomical community about interesting phenomena in the X-ray sky. SSM comprises position sensitive proportional counters with 1D coded mask for imaging. There are three detector units mounted on a platform capable of rotation which helps covering about 50% of the sky in one full rotation. This paper discusses the elaborate details of the instrument and few immediate results from the instrument after launch. 相似文献
44.
Avalanches are behind the majority of fatalities and heavy damage to property in snow-covered mountainous terrain like Himalaya. Recognizing avalanche susceptible areas and publication of avalanche susceptibility maps assist decision-makers and planners to execute suitable measures to reduce the avalanche risk. The present study is an attempt to prepare an avalanche susceptibility map of the Nubra valley region using multi-criteria decision analysis–analytical hierarchy process model in GIS environment. The most prominent avalanche occurrence factors used in this model are slope, aspect, curvature, elevation, terrain roughness and ground cover. ASTER GDEM V2 and Landsat 8 satellite imagery were used to generate considered factors. For validation of the results, prediction rate/accuracy is calculated using the avalanche inventory map of documented avalanche locations. To calculate the prediction accuracy, area under the ROC curve (ROC-AUC) method has been used. The prediction accuracy of the validation results using ROC-AUC shows 91%. 相似文献
45.
46.
Kasturi Chakraborty P. K. Mukhopadhyay Praveer Pankaj 《Journal of the Geological Society of India》2016,87(6):631-660
The western part of Cuddapah basin has been considered as a foreland to the fold-thrust belt represented by eastern Nallamalais and Nellore schist belt. The igneous activities, in the form of lava flows and sills, in western Cuddapahs have been a subject of controversy since tectonogenetic models ranging from a mantle plume to lithospheric extension have been suggested. The present work covers a detailed study of the mafic sills and lava flows of Vempalle and Tadpatri formations in western Cuddapahs, which earlier workers have also noted. A detailed field and laboratory work in this study brings out, for the first time, five distinct petrographic and geochemical varieties of sills. Geochemical studies also suggest that the different sill types have originated from varying degrees of partial melting of a metasomatized subcrustal lithospheric mantle, the metasomatism of source being attributed to older Archaean convergent settings/greenstone belts that the basin unconformably overlies. The possible contribution of any small plume is only heating and doming of overlying mantle that induced incipient crustal rifting. Our geochemical studies on the lava flows of Vempalle Formation also suggest that the magma was derived from small degree of partial melting of spinel-garnet peridotite mantle in a rift setting. 相似文献
47.
48.
The probability of landslide volume, V
L
, is a key parameter in the quantitative hazard analysis. Several studies have demonstrated that the non-cumulative probability
density, p(V
L
), of landslide volumes obeys almost invariably a negative power law scaling of p(V
L
) for landslides exceeding a threshold volume and a roll-over of small landslides. Some researchers attributed the observed
roll-over to under-sampling of data, while others relate it to a geo-morphological (physical) property of landslides. We analyzed
15 sets of a complete landslide inventory containing shallow debris slides (2 ≤ V
L
≤ 3.6 × 103 m3) with sources located on cut slopes along a 17-km-long railroad corridor. The 15 datasets belong to individual years from
1992 to 2007. We obtained the non-cumulative probability densities of landslide volumes for each dataset and analyzed the
distribution pattern. The results indicate that for some datasets the probability density exhibits a negative power law distribution
for all ranges of volume, while for others, the negative power scaling exists only for a volume greater than 10 m3, with scaling exponent β varying between 0.96 and 2.4. When the spatial distribution of landslides were analyzed in relation to the terrain condition
and triggering rainfall, we observed that the number of landslides and the range and the frequency of volumes vary according
to the changes in local terrain condition and the amount of rainfall that trigger landslides. We conclude that the probability
density distribution of landslide volumes has a dependency on the local morphology and rainfall intensity and the deviation
of small landslides from power law, i.e., the roll-over is a “real effect” and not an artifact due to sampling discrepancies. 相似文献
49.
In this study, stochastic finite fault modeling is used to simulate Uttarkashi (1991) and Chamoli (1999) earthquakes using all available source, path, and site parameters available for the region. These two moderate earthquakes are recorded at number of stations of a strong motion network. The predicted peak ground accelerations at these stations are compared with the observed data and the ground motion parameters are constrained. The stress drop of Uttarkashi and Chamoli earthquakes is constrained at 77 and 65?bars, respectively, whereas the quality factor Q C is 112 $ f^{0.97} $ and 149 $ f^{0.95} $ for these two regions. The high-frequency attenuation parameter Kappa is in the range 0.04?C0.05. The constrained ground motion parameters are then used to simulate Mw 8.5 earthquake in central seismic gap region of Himalaya. Two scenarios are considered with epicenter of future great earthquake at locations of Uttarkashi and Chamoli earthquakes using above constrained parameters. The most vulnerable towns are the towns of Dehradun and Almora where expected PGA is in excess of 600?cm/s2 at VS30 520?m/s when the epicenter of the great earthquake is at the location of Uttarkashi (1991) earthquake. The towns of Shimla and Chandigarh can expect PGA close to 200?cm/s2. Whereas when the epicenter of the great earthquake is at the location of Chamoli (1999) earthquake, the towns of Dehradun and Almora can expect PGA of around 500 and 400?cm/s2, respectively, at VS30 620?m/s. The National Capital Region, Delhi can expect accelerations of around 80?cm/s2 in both the cases. The PGA contour maps obtained in this study can be used to assess the seismic hazard of the region and identify vulnerable areas in and around central Himalaya from a future great earthquake. 相似文献
50.
Major Hα solar-flare events of high optical importance have been employed to study their heliographic distribution in longitude around
the Sun for the period of 2001 to 2006. A statistical analysis was performed to obtain their relationship with halo/partial-halo
CMEs and Forbush decreases (Fds) of cosmic-ray intensity. Our analysis indicates that 63% of the solar flares associated with
halo CMEs and Fds occur in the western hemisphere and of 37% of such flares occur in the eastern hemisphere. Similarly, we
found that nearly 60% of the solar flares associated with partial- halo CMEs and Fds occur in the western hemisphere and the
rest (40%) occur in the eastern hemisphere. Finally, we conclude that the flares in association with CMEs and located in the
western hemisphere of the solar disk are more effective in producing Fds. The magnitudes of Fds are observed to be higher
when in association of halo CMEs. A slight excess in the eastern hemisphere is found for both the halo and partial-halo CMEs. 相似文献