The electrostatic ion-cyclotron instability (EICI) in low β (ratio of plasma to magnetic pressure), anisotropic, inhomogeneous
plasma is studied by investigating the trajectories of the particles using the general loss-cone distribution function (Dory-Guest-Harris
type) for the plasma ions. In particular, the role of the loss-cone feature as determined by the loss-cone indices, in driving
the drift-cyclotron loss-cone (DCLC) instability is analysed. It is found that for both long and short wavelength DCLC mode
the loss-cone indices and the perpendicular thermal velocity affect the dispersion equation and the growth rate of the wave
by virtue of their occurrence in the temperature anisotropy. The dispersion relation for the DCLC mode derived here using
the particle aspect analysis approach and the general loss-cone distribution function considers the ion diamagnetic drift
and also includes the effects of the parallel propagation and the ion temperature anisotropy. It is also found that the diamagnetic
drift velocity due to the density gradient of the plasma ions in the presence of the general loss-cone distribution acts as
a source of free energy for the wave and leads to the generation of the DCLC instability with enhanced growth rate. The particle
aspect analysis approach used to study the EICI in inhomogeneous plasma gives a fairly good explanation for the particle energisation,
wave emission by the wave–particle interaction and the results obtained using this particle aspect analysis approach are in
agreement with the previous theoretical findings using the kinetic approach. 相似文献
The tropical cyclones are very destructive during landfall, generating high wind speeds, heavy intensive rainfall, and severe storm surges with huge coastal inundations that have massive socioeconomic and ecological catastrophic effects on human beings and the economic well-being. The sizable ecological effects of cyclonic storms cannot be ignored because of the uncertainty of impact, intensity induced by a warming ocean, and sea level rise. The Super Cyclonic Storm Amphan which falls under the category five classifications under the scheme of the India Meteorological Department (IMD), on the basis the maximum sustained wind speeds gusting up to 168 km/h affected parts of West Bengal and Odisha in India, and south-west Bangladesh between May 16 and 20, 2020. In this work, we have focused on the coastal districts of Kendrapada, Bhadrak, Balasore in Odisha, Purba Medinipur, and South Twenty-Four Parganas in West Bengal, India and, Khulna, Barisal division of Bangladesh that have been seriously affected by the Super Cyclonic Storm Amphan. The objective of the study is to analyze the eco-physical assessment of tropical cyclone Amphan using geospatial technology. Therefore, shoreline change detection and enhance vegetation index have been used in this research work to systematically analyze the eco-physical impact parameters of Cyclonic Storm Amphan using ortho-rectified Landsat 8/OLI imagery and MODIS dataset of USGS with high spatial resolutions of 30–500 m. The result highlights that about 60.33% of the total transects of the study area was eroded, but only 24.99% of the total transects experienced accretion, and 14.68% of the total transects depicted stability. The scientific study will benefit coastal managers and policymakers in formulating action plans for coastal zone management, natural resilience, and sustainable future development.
Geotechnical and Geological Engineering - The bonded-particle model (BPM) method has been used to study the size effect and anisotropy of rock strength. This research proposes a new bonded-particle... 相似文献
Geotechnical and Geological Engineering - This paper presents the effect of impact load and weathering of surrounding rockmass on the deformation behavior of urban underground structures. The FEM... 相似文献
Ice sheets investigation is important with regard to climate change and contribution to the sea level rise or fall. Radar altimetry in complement with laser altimetry can serve as a suitable candidate for precise monitoring of ice sheet evaluations. SARAL due to higher observation into the polar region (up to 82.5°N) can cover nearly 100% of the Greenland ice sheet. Continuous ice tracking mode retracker can provide useful information about ice surfaces, that is, determining the snow coverage, ice sheet transaction margin, and the evolution of snow depth during winter more accurately. This study present the results obtained with SARAL satellite Altika radar altimeter over the Greenland ice sheet region. The altimeter high rate waveforms products are used for utilizing the full capability of the instrument. High resolution DEM (1 km) generated using ICESAT/GLAS altimeter has been used for selecting the good quality data over the study region. Four different retrackers—Ocean, ICE-1, ICE-2, and Sea-Ice—were tested on the SARAL altimeter data set and compared with the DEM extracted ice sheet elevations. Three different data analysis—region of interest (ROI), track analysis, and cross-over analysis—were performed for in-depth analysis of the ice height changes and back scattering coefficient variability. ROI's (1° × 0.5°) were selected based on accumulation dry snow zone, percolation zone, wet snow zone, and ablation zone. Finally to observe the effect of Ka band, SARAL results has been compared with the Envisat altimeter in terms of back scatter and error in the height retrieval due to penetration problem within the ice sheet layer. The new SARAL data set confirms the potential of ice altimetry and provides a new opportunity to monitor the ice sheet surface topography evolution. 相似文献
In this paper an analytical method has been proposed to predict the net ultimate uplift capacity of the single bent pile and
pile group with a bent embedded in sand considering arching effects. Arching develops due to relative compressibility of sand
relative to pile which activates the soil-pile friction. The method takes into consideration the embedded length (L), diameter of the pile (d), bent angle, surface characteristics of pile, group configuration, spacing of the pile group and the soil properties. Log
spiral failure surface with parabolic arch shape was assumed in the analysis. Theoretical investigation for uplift capacity
was been carried out for the single bent pile and group of pile (2 × 1, 2 × 2) embedded in sand. The variable used in the
analysis were embedded length to pile diameter (L/d = 15, 20 and 25), spacing in the group (3d, 4d and 6d) and angle of bent (6°, 14° and 20°). Typical charts for evaluation of net ultimate uplift capacity for pile groups are presented
through the figures. Comparison of theoretical results shows good agreement with established experimental results. 相似文献
When neglecting capillarity, two-phase incompressible flow in porous media is modelled as a scalar nonlinear hyperbolic conservation
law. A change in the rock type results in a change of the flux function. Discretising in one dimension with a finite volume
method, we investigate two numerical fluxes, an extension of the Godunov flux and the upstream mobility flux, the latter being
widely used in hydrogeology and petroleum engineering. Then, in the case of a changing rock type, one can give examples when
the upstream mobility flux does not give the right answer. 相似文献