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The problem of nonlinear localized dust acoustic (DA) is addressed in a plasma comprising positive ions, negative ions, and
mobile negatively charged dust grains. We first consider the case when the grain charge remains constant and discuss later
the case when the charge variations are self-consistently included. It is found that a relative increase of the positive ion
density favors the propagation of the DA solitary waves, in the sense that the domain of their admissible Mach numbers enlarges.
Furthermore, electronegativity makes the dust acoustic solitary structure more spiky. When the dust grain charge Q
d
is allowed to fluctuate, the latter is expressed in terms of the Lambert function and we take advantage of this transcendental
function to investigate the variable charge DA solitary wave. Q
d
adopts a localized profile and becomes more negative as the number of charges Z
(−) of the negative ion increases. The dust grains are found to be highly localized. This localization (accumulation) caused
by a balance of the electrostatic forces acting on the dust grains becomes more effective for lower values of Z
(−). An increase of Z
(−) may lead to a local depletion of the negative ions from the region of the soliton’s localization. The results are useful
to understand the salient features of localization of large amplitude dust acoustic waves in cosmic plasmas such as the ionospheric
D-region and the mesosphere. 相似文献
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The concept of ion nonthermality is generalized within the theoretical framework of the Tsallis thermostatistics. In this
connection, a physically meaningful ion distribution function is outlined. As the nonextensive character of the nonthermal
ions increases, the distribution shoulders may become less or more prominent and high energy states are less or more probable
than in the extensive nonthermal case. Variable charge dust acoustic waves are then addressed. We first consider the case
of adiabatic dust charge variation and discuss later the case when the nonadiabatic charge variations are self-consistently
included. Our results may complement and provide new insight into previously published work in nonthermal space plasmas. 相似文献
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Moufida El May Mahmoud Dlala Aouicha Bedday 《Central European Journal of Geosciences》2011,3(3):260-270
Before construction activities could begin, engineering geological and geotechnical investigations had to be approved in order to establish a map with suitable areas for safe construction. The example used in this study is Tunis City which has complex geology and geomorphology. The risk analysis was based on a large-scale land-suitability map that was prepared using Geographic Information Systems (GIS). The approach used in this study combined physical data with the geotechnical properties of Tunis City. The adopted methodology and analyses were performed to assess the risk of urban expansion and landscape management. Results are presented as a zoning map that shows the suitable area for safe extension of the urban area. The data used and multi-criterion analysis of geotechnical and geological data seems to be useful for similar case studies and the adopted methodology can be used successfully for identifying similar cities for risk assessment. 相似文献
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Mapping groundwater recharge potential zones in arid region using GIS and Landsat approaches,southeast Tunisia 总被引：1，自引：0，他引：1
Dhekra Souissi Mohamed Haythem Msaddek Lahcen Zouhri Ismail Chenini Moufida El May Mahmoud Dlala 《水文科学杂志》2018,63(2):251-268
The rapid growth of population and agricultural and industrial activities has caused an increase in demand on the Jeffara aquifers of Gabes (southeast Tunisia). In fact, the over-pumping of this aquifer system has resulted in water-level declines ranging from 0.25 to 1 m/year during the past three decades. The aim of this study is to identify favourable artificial recharge sites of this aquifer system based on the combined use of remotely sensed data, a geographic information system (GIS), the Shuttle Radar Topography Mission (SRTM) product and a multiple criteria decision making (MCDM) technique. The delineation of artificial recharge zones shows high to moderate potential for groundwater recharge (40%) in the Gabes region, with high precision of good potential proposed sites. Recharge processes need to account for natural conditions and ecosystems. 相似文献
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