Diffuse solar radiation and associated meteorological parameters in India

International audienceSolar diffuse radiation data including global radiation, shortwave and longwave balances, net radiation and sunshine hours have been extensively analyzed to study the variation of diffuse radiation with turbidity and cloud discharges appearing in the form of atmospherics over the tropics. Results of surface radiation measurements at Calcutta, Poona, Delhi and Madras are presented together with some meteorological parameters. The monthly values of diffuse radiation and the monthly ratios of diffuse to global solar radiation have been examined, with a special emphasis in relation to the noise level of atmospherics at Calcutta in the very low frequency band. The results exhibit some definite seasonal changes which appear to be in close agreement with one another

Long-period fading in atmospherics during severe meteorological activity and associated solar geophysical phenomena at low latitudes

International audienceThe records of VLF atmospherics over Calcutta and then over Kalyani (West Bengal) during the torrential rainfall, caused by violent monsoon and post-monsoon depressions, exhibit distinct long-period fadings both at day and night. Interesting results obtained from an analysis of round-the-clock atmospherics data and associated meteorological parameters are reported in this paper. A possible correlation between the severe meteorological activity with the solar geophysical phenomena was studied. The results are indicative of an interesting sequence of solar-terrestrial events. A tentative conclusion is reached, suggesting an origin of the fading from atmospheric gravity waves generated in the centre of activity of the depressions concerned

Amorphization of Vortex Matter and Reentrant Peak Effect in YBa2_2Cu3_3O7−δ_{7-\delta}

The peak effect (PE) has been observed in a twinned crystal of YBa$_2$Cu$_3$O$_{7-\delta}$ for H$\parallel$c in the low field range, close to the zero field superconducting transition temperature (T$_c$(0)) . A sharp depinning transition succeeds the peak temperature T$_p$ of the PE. The PE phenomenon broadens and its internal structure smoothens out as the field is increased or decreased beyond the interval between 250 Oe and 1000 Oe. Moreover, the PE could not be observed above 10 kOe and below 20 Oe. The locus of the T$_p$(H) values shows a reentrant characteristic with a nose like feature located at T$_p$(H)/T$_c$(0)$\approx$0.99 and H$\approx$100 Oe (where the FLL constant a$_0$$\approx$penetration depth $\lambda$). The upper part of the PE curve (0.5 kOe$<$H$<$10 kOe) can be fitted to a melting scenario with the Lindemann number c$_L$$\approx$0.25. The vortex phase diagram near T$_c$(0) determined from the characteristic features of the PE in YBa$_2$Cu$_3$O$_{7-\delta}$(H$\parallel$c) bears close resemblance to that in the 2H-NbSe$_2$ system, in which a reentrant PE had been observed earlier.Comment: 15 pages and 7 figure

Basic Electric Furnace Practice for Low Alloy Steels

The low alloy steels generally find application in the construction of automobiles, locomotives, bridges, mach-inery and machine tools and many other equipment. These steels are used in "as forged" or "as rolled" condition or is as castings after suitable heat-treatment, to develop the properties desired. The chief alloying elements ill low alloy steels are Ni, Cr, Mn, Ito, V. Si, and Cu. These elements are used either singly or very often in combination with others ill, various proportions : the total of the alloying elements generally does not exceed 8 per cent

On Some properties of Di-hadronic states

The binding energies of di- hadronic states have been calculated assuming a 'molecular' interaction provided by the asymptotic expression of the residual confined gluon exchange potential between the component hadrons in the system. Meson- meson and meson- baryon states have been studied in detail and a mass formula has been used to calculate total mass of the 'molecules'.Comment: 11 page