Supernovae and the Ap phenomenon     

R. Rajamohan  Ashok K. Pati 《Journal of Astrophysics and Astronomy》1980,1(2):155-164

We put forward evidence that relates the phenomenon of the chemically peculiar stars of the upper main sequence to Supernovae explosions in young clusters. In the Upper Scorpius region we find that a supernova shell has interacted with dense clouds and that the peculiar stars lie close to or along the edges of interaction. We argue that the stars at or near the cloud faces are capable of acquiring this enriched material which is sufficiently slowed down. The magnetic accretion process of Havnes and Conti provides the mechanism of acquisition. This process with the associated magnetic braking accounts for the build-up in abundance anomalies and the slowing down of rotation with age.  相似文献   

Laboratory investigation of pullout behavior of hollow and solid shaft helical nail in frictional soil     

Sharma  Pankaj  Rawat  Saurabh  Gupta  Ashok Kumar 《Acta Geotechnica》2021,16(4):1205-1230

Acta Geotechnica - Helical soil nails are passive elements installed in the soil which attains its bond strength through skin friction and bearing from helices. The present study examines the...  相似文献   

Sensitivity Analysis of Coal Rib Stability for Internal Mine Dump in Opencast Mine by Finite Element Modelling     

Tushar Gupta  Rajesh Rai  Ashok Jaiswal  B. K. Shrivastva 《Geotechnical and Geological Engineering》2014,32(3):705-712

The present paper discusses the impact of the geometrical parameters of the coal rib and the mine dump on the stability of the coal rib. The geometrical parameters such as the slope angle, the height of dragline dump, the height of main dump, the gradient of seam and the thickness of coal rib have been considered as input to the numerical model for the stability analysis of the coal rib. Sensitivity analysis has been performed based on the results of the analysis in term of factor of safety of the coal rib. The input parameters have been classified in terms of significance (i.e. very high significance, high significance medium significance and low significance). The factor of safety is more influenced by highly significant parameters. The height and the slope angle of dragline dump and the thickness of the coal rib are highly significant parameters for the stability of the coal rib. The gradient of the seam is a medium significant parameter whereas, height of main dump and the number of dragline cut dump are low significant parameters for stability of coal rib.  相似文献   

Coherence Inherent in an Incoherent Synchrotron Radio Source     

Ashok K. Singal 《Journal of Astrophysics and Astronomy》2011,32(4):447-450

We show that a partial coherence due to antenna mechanism can be inherently present in any compact synchrotron source, which resolves many long-standing problems in the spectra and variability of compact extragalactic radio sources.  相似文献