Vikram Sarabhai Space Centre

About: Vikram Sarabhai Space Centre is a facility organization based out in Thiruvananthapuram, India. It is known for research contribution in the topics: Aerosol & Ultimate tensile strength. The organization has 2092 authors who have published 3058 publications receiving 47975 citations. The organization is also known as: VSSC.

Long‐term variability of the low latitude mesospheric SAO and QBO and their relation with stratospheric QBO

Abstract: [1] Long term variations of low-latitude mesospheric semi-annual oscillation (MSAO) and quasi-biennial oscillation (MQBO) in the zonal wind are studied using observations available from 1977 to 2006. The MQBO showed large inter-annual variability in the phase difference between 77.5 km and 72.5 km indicating such variability in eddy viscosity. Association of these oscillations with stratospheric quasi-biennial oscillation (SQBO) is investigated. In general, the MQBO at 77.5 km is out-of-phase with SQBO and this relation fails during strong and long SQBO. The MSAO at 72.5 km and 77.5 km generally shows strong westward phase during strong eastward phase of SQBO. The most striking feature observed in the present study is the strong modulation of the MSAO by MQBO revealing a non-linear type of interaction with presence of sidebands of the MSAO.

Cyanate esters based on cardanol modified‐phenol‐formaldehyde resins: Syntheses and thermal characteristics

Abstract: Cardanol incorporated-phenol-formaldehyde novolac resins were synthesi- zed by acid and base catalyzed reactions. The novolacs were transformed to their cyanate esters. The thermal cure characteristics of the cyanate esters depended upon the composition. The presence of cardanol propor- tionately facilitated the curing. The thermal characterization of the novolacs and the corresponding cured phenolic-triazine networks indi- cated a dedicated a detremental effect of cardanol on the thermal stability and char residue of the resins

Atmospheric Surface-Layer Processes During the Total Solar Eclipse Of 11 August 1999

Abstract: The central path of the total solar eclipse (TSE) of 11 August 1999 mostly passedthrough a region of active monsoon in India, with the eclipse ending around localsunset. Measurements in the surface layer (SL) were carried out close to the eclipseaxis at Akola (20°42' N, 77°2' E) in central India. The globalradiation flux reaching the surface vanishes around totality at 1803:24 (LT), followedby a small recovery before again dipping to zero at sunset. The temperatures in the SL, and subsoil at 50-mm depth, show a local minimum with a lag of about 10 min after the second contact, whereas the lag appears to vanish when the temperature series is detrended. The SL exhibits near-neutral, though generally stable, conditions from about 1500 hr itself due to heavy cloud cover followed by the eclipse-induced cooling of the surface. The wind component across the eclipse axis vanishes at totality, the wind vector aligning with the azimuth of the traversing moon shadow. The deceleration of the mean flow can be due to the combined effect of the colder surface and downward heat flux, where the locally altered horizontal temperature gradients may cause, as in this instance, the cessation of the cross flow. The oscillations in temperature and wind that show significant peaks, around 90–100 min as well as the semi-period of the eclipse near 60 min, persist for several hours past the eclipse event. A fresh analysis of the published data on the TSE of 7 March 1970 shows spectral peaks in the temperature nearly coincident with those already reported from the surface pressure records. The oscillations in the SL fields during the two TSE events are very similar implying that the source mechanism is also likely to be the same in both the cases.