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.

Densification behavior and mechanical properties of Cu–Cr–Nb alloy powders

Abstract: The densification behavior of hot-pressed Cu–8 at%Cr–4 at%Nb alloy powders and concurrent effect of densification on the mechanical behavior have been studied as a function of applied stress and sintering temperature. The densification of alloy powder has been observed to be strongly inhibited by the presence of fine scale distribution of Cr2Nb precipitates. It is interesting to note that the mechanical properties are linearly related to sintered densities at different stress values and temperatures. Finally, the structure property correlation has been established.

Periodic orbits of the second kind in the restricted three-body problem when the more massive primary is an oblate spheroid

Abstract: Utilizing secular perturbing potential due to oblateness, the existence of periodic orbits of the second kind is established through analytic continuation using Delaunay's canonical variables in the planar restricted three-body problem when the more massive primary is an oblate spheroid with its equatorial plane coincident with the plane of motion.

Lithium doped polyaniline and its composites with LiFePO4 and LiMn2O4-prospective cathode active materials for environment friendly and flexible Li-ion battery applications

Abstract: The present work is aimed at investigating the electrochemical properties of Li-ion cells, assembled using lithium substituted polyaniline and its composites with LiFePO4 and LiMn2O4 as the cathode active materials. Lithium substitution in PANI can be achieved by a variety of approaches and the present work introduces one of the cost effective methods using a comparatively cheaper lithium salt, n-butyllithium in hexanes (n-BuLi) as the dopant. X-ray diffraction, FTIR and SEM techniques were used to get the structural and surface morphological details of the Li-substituted PANI (LIPO) samples. Coin cells were assembled in the glove box using LIPO as cathode and lithium metal foil as anode with 1 M LiPF6 in EC:DMC (1:1) as electrolyte. Voltage sweep cyclic voltammetry and charge–discharge cycling were employed to characterize the electrochemical capabilities of the assembled cells. The cells are found to show a maximum discharge capacity of 25.04 mA h g−1 with 99.99% columbic efficiency and have got tremendous cycling stability over 50 cycles. Pouch cells were assembled using LIPO samples as cathode active materials, graphite as anode and gel polymer (poly(ethylene oxide)) as electrolyte. The pouch cells are found to hold the open circuit voltage of 0.6 V (OCV) even when bent up to 90° from the initial state, which provides the first signature of constructional flexibility of these polymer based Li ion cells. Hoping to improve the specific capacity of LIPO based cells, composite cathode materials were synthesized by mixing LIPO samples with LiFePO4 and LiMn2O4 in 9:1 ratio by weight. The cells are found to show a maximum discharge capacity of 37 mA h g−1 with 99.99% columbic efficiency and have got excellent cycling stability over 50 cycles. One of the highlights of these studies is the observation that the inherent Jahn–Teller effect associated with LiMn2O4 cathode material can be eliminated to a great extent by making composites with LIPO samples.

Tropospheric carbon monoxide over the northern Indian Ocean during winter: influence of inter-continental transport

Abstract: South Asian outflow over the adjoining marine regions is most pronounced during winter season, whereas the prevalence of strong winds aloft can transport the influences from inter-continental sources. Here, we investigate the tropospheric carbon monoxide (CO) distribution over the northern Indian Ocean (IO) combining shipborne measurements carried out during the Integrated Campaign for Aerosols, gases, and Radiation Budget (ICARB) campaign (January–February 2018), retrievals from Measurements of Pollution in the Troposphere (MOPITT), and Copernicus Atmosphere Monitoring Service (CAMS) model. Surface CO varied from ~ 50 to 365 ppbv (179 ± 67 ppbv) with higher levels over the coastal region of southeast Arabian Sea and lower levels over the equatorial IO. We observed lower CO levels (200 ± 43 ppbv) than those during the Indian Ocean Experiment-1999 (229 ± 40 ppbv) supporting the reported decreasing trend of tropospheric CO. In situ CO observations are found to be in a good agreement with the satellite retrievals (MOPITT-version 8) as well as the CAMS model results (r2 = 0.60‒0.65). The upper-tropospheric CO (300‒200 hPa) over the equatorial IO is observed to be higher by up to 30% during February-2018 as compared to the decadal mean, coinciding with anomalous westerlies resulting from a disturbed Walker cell over the equatorial IO and deeper penetration of the sub-tropical jet. The influences of African forest fires are suggested to have enhanced the upper-tropospheric CO over the IO during February-2018. Our study highlights the importance of strong large-scale dynamics and global biomass-burning emissions in the wintertime pollution loading over the IO, besides the South Asian outflow.