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121.
D. P. Sharma T. M. K. Marar S. Seetha K. S. Shyla K. Kasturirangan U. R. Rao J. C. Bhattacharyya M. J. Rozario 《Astrophysics and Space Science》1983,91(2):467-476
The discovery of a flare star (R.A. (1950)=6h43m6s.07, Decl.(1950)=?16°45′24″) located about 6 arc min south of Sirius is reported. During photometric observations on the night of 13 January, 1982, using the 102 cm telescope at Kavalur, India, the star was seen to brighten by 2.55 mag. inV band over a duration of about 200 s. Observations on this object for a duration of about 10.5 hr spread over seven more nights indicate the star to be variable. The results of these observations are presented. 相似文献
122.
K. C. Sharma 《Astrophysics and Space Science》1982,85(1-2):263-269
The gravitational instability of an infinite homogeneous and infinitely conducting selfgravitating gas particle medium in the presence of suspended particles of a Hall plasma is considered. The particular cases of the effects of Hall currents and suspended particles on the waves propagated along and perpendicular to magnetic field have been discussed. Jeans's criterion determines the gravitational instability. 相似文献
123.
The thermosolutal-convective instability of a stellar atomsphere is studied in the presence of suspended particles. The criteria
for monotonic instability are derived and are found to hold good also in the presence of uniform rotation and uniform magnetic
field on the thermosolutal-convective instability. The thermosolutal-convective instability of a stellar atmosphere is also
studied in the presence of suspended particles and radiative transfer effects and the criteria for monotonic instability are
obtained in terms of source function. 相似文献
124.
The gravitational instability of flow through porous medium for some hydrodynamical and hydromagnetical systems of astrophysical interest is investigated. The effects of rotation, magnetic field, viscosity and finite electrical conductivity are studied for the gravitational instability through porous medium. The effect of suspended particles on the instability is also considered. It is found that Jean's criterion remains unchanged in the presence of porosity, viscosity, finite conductivity, rotation, magnetic field and suspended particles in the medium. 相似文献
125.
126.
Nonlinear analysis of electrostatic drift Kelvin-Helmholtz instability is performed. It is shown that the analysis leads to the propagation of the weakly nonlinear dispersive waves and the nonlinear behaviour is governed by the nonlinear Burger's equation. 相似文献
127.
The thermal-convective instability of a composite stellar atmosphere is considered in the presence of rotation, variable horizontal magnetic field, and collisional effects. The criteria for monotonic instability are obtained which generalize the criterion derived for thermal-convective instability in the absence of above effects. 相似文献
128.
The use of the limit equilibrium method for the analysis of a dam foundation with a weak shear seam has many limitations. There is further uncertainty in such an analysis by this method when the seam is intercepted by a concrete key. The finite element method is the best alternative means of analysing such problems. In this paper, the finite element analysis of the Karjan Dam (India) foundation, which has a shear seam, is presented with and without the foundation treatment (i.e. the concrete key). The seam is simulated by joint elements. It has been found that a concrete key located near the toe of the dam significantly improves the stability of the foundation. 相似文献
129.
A. Datta T. Saud A. Goel S. Tiwari S. K. Sharma M. Saxena T. K. Mandal 《Journal of Atmospheric Chemistry》2010,65(2-3):127-143
The temporal variation of ambient SO2 and the chemical composition of particulate matters (PM2.5 and PM10) were studied at National Physical Laboratory (NPL), New Delhi (28°38′N, 77°10′E). Spatial variation of SO2 at seven air quality monitoring stations over Delhi was also studied simultaneously. Wide range of ambient SO2 was recorded during winter (2.55 to 17.43 ppb) compare to other seasons. SO2 mixing ratio was recorded significantly high at industrial sites during winter and summer; however, no significant spatial difference in SO2 mixing ratio was recorded during monsoon. SO 4 2? /(SO2+SO 4 2? ) ratio was recorded high (0.74) during winter and low (0.69) during summer. Monthly variation of PSCF was analyzed using HYSPLIT seven days backward trajectories and daily average SO2 data. PSCF analysis suggests that, during winter (December, January, February) ambient SO2 at the study site might have contributed from long distance sources, located towards west and southwest directions; during monsoon (July, August, September) marine contribution was noticed; whereas, during summer (April, May and June) it was from regional sources (located within few 100 km of study site). During winter there was significant contribution from the long distance sources located in western Asia, northwestern Pakistan, Rajasthan and Punjab provinces of India. Coal used in thermal power plants at Panipat (in the northwestern side) and Faridabad (in the southeastern side), local industries, soil erosion and biomass burning may be major contributing factors for SO2 during summer. The study establishes that the transport sector may not be the major source of ambient SO2 in Delhi. 相似文献
130.
Vulnerability and adaptation to climate variability and water stress in Uttarakhand State, India 总被引:1,自引:0,他引:1
Ulka Kelkar Kapil Kumar Narula Ved Prakash Sharma Usha Chandna 《Global Environmental Change》2008,18(4):564
This paper presents a participatory approach to investigate vulnerability and adaptive capacity to climate variability and water stress in the Lakhwar watershed in Uttarakhand State, India. Highly water stressed microwatersheds were identified by modelling surface runoff, soil moisture development, lateral runoff, and groundwater recharge. The modelling results were shared with communities in two villages, and timeline exercises were carried out to allow them to trace past developments that have impacted their lives and livelihoods, and stimulate discussion about future changes and possible adaptation interventions. 相似文献