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Institution

Vikram Sarabhai Space Centre

FacilityThiruvananthapuram, India
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.


Papers
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Journal ArticleDOI
TL;DR: In this article, the authors classified the onset of equatorial spread F observations into three categories based on ionograms recorded over Sriharikota and found that the peak h′F values were remarkably different in the three categories indicating a zonal variation of eastward electric field and postsunset height rise of F layer.
Abstract: Equatorial spread F observations have been categorized into three categories based on ionograms recorded over Sriharikota. First category comprised cases where the onset of equatorial spread F (ESF) was concurrent with the peak h′F time. Second and third categories comprised cases where the onset of ESF happened with a delay of 30 min and more than 30 min, respectively, with reference to the peak h′F time. Average peak h′F in the first category was more than 35 km higher than that in the second and third categories. Also, the peak vertical (upward) plasma drift was higher in the first category. Assuming the genesis of F region irregularity to have happened at or before the time of F layer attaining the peak height, late onset of ESF indicates the genesis of irregularities to have happened westward of Sriharikota. The fact that the peak h′F values were remarkably different in the three categories indicates a zonal variation of eastward electric field and postsunset height rise of F layer. The relative magnitude of the F layer height rise in the three different categories over Sriharikota has also been found to be significantly different than that over Thumba, an equatorial (magnetic) station located ~360 km westward of Sriharikota longitude. This scenario points toward the existence of a large-scale zonal standing wave in the F layer and its important role in F region instability process. Results presented in the manuscript have been discussed in the light of current understanding on the large-scale wave structure.

17 citations

Journal ArticleDOI
TL;DR: In this article, fracture toughness of adhesively bonded composite joints is experimentally investigated for the basic fracture modes, and the results indicate that acoustic emission signals have good correlation with load-displacement behavior to determine the fracture initiation stage especially in the mode-II loading.

17 citations

Journal ArticleDOI
TL;DR: In this article, electric field values from VHF backscatter radar measurements at Thumba (dip: 56′S) of the phase velocities of type II irregularities in the equatorial electrojet (EEJ), electric field (E y ) values are estimated for different times of the day.

17 citations

Journal ArticleDOI
TL;DR: In this paper, a comparative study of some formulation variables was made for their effect in improving the flow characteristics and mechanical properties of an aluminized polyurethane (PU) propellant system based on hydroxyl terminated natural rubber (HTNR).
Abstract: Hydroxyl terminated natural rubber (HTNR) was prepared by the depolymerization of masticated natural rubber in the presence of H2O2 in toluene. Probable mechanisms leading to the formation of side reaction products are proposed based on the analytical data. A comparative study of some formulation variables was made for their effect in improving the flow characteristics and mechanical properties of an aluminized polyurethane (PU) propellant system based on HTNR. This PU system has also been compared for its theoretical performance characteristics with some other state-of-the-art systems.

17 citations

Journal ArticleDOI
TL;DR: In this paper, cyclomatrix phosphazene-triazine network polymers were synthesized by co-curing a blend of tris(2-allylphenoxy), triphenoxy cyclotriphosphazene (TAP), and tris (2-all-phenoxy) s-triphenoxy triazine (TAT) with bis(4-maleimido phenyl) methane (BMM).
Abstract: Cyclomatrix phosphazene–triazine network polymers were synthesized by co-curing a blend of tris(2-allylphenoxy), triphenoxy cyclotriphosphazene (TAP), and tris(2-allylphenoxy) s-triazine (TAT) with bis(4-maleimido phenyl) methane (BMM). The co-curing of the three-component resin was investigated by dynamic mechanical analysis using rheometry. The cure kinetics of the Diels–Alder step was studied by examining the evolution of the rheological parameters, such as storage modulus (G′), loss modulus (G″), and complex viscosity (η*), for resins of varying compositions at different temperatures. The curing conformed to an overall second-order phenomenological equation, taking into account a self-acceleration effect. The kinetic parameters were evaluated by multiple-regression analysis. The absence of a definite trend in the cure process with blend composition ratio was attributed to the occurrence of a multitude of competitive reactions whose relative rates depend on the reactant ratio and the concentration of the products formed from the initial phase of reaction. The cure was accelerated by temperature for a given composition, whereas the self-acceleration became less prominent at higher temperature. Gelation was accelerated by temperature. The gel conversion decreased with increase in maleimide concentration and, for a given composition, it was independent of the cure temperature. The activation energy for the initial reaction and the crosslinking process were estimated for a composition with a maleimide-to-allyl ratio of 2 : 1. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 88: 908–914, 2003

17 citations


Authors

Showing all 2111 results

NameH-indexPapersCitations
M. Santosh103134449846
Sabu Thomas102155451366
S. Suresh Babu7049817113
K. Krishna Moorthy542639749
Sathianeson Satheesh5317211099
M. Y. Hussaini4920716794
J.R. Banerjee441465620
C. P. Reghunadhan Nair371814825
K. N. Ninan361594156
Anil Bhardwaj352304527
Ivatury S. Raju331216626
Venkata Sai Kiran Chakravadhanula321023011
P.K. Sinha321182918
J.-P. St.-Maurice311133446
Subramaniam Gopalakrishnan281232951
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Performance
Metrics
No. of papers from the Institution in previous years
YearPapers
202313
202230
2021186
2020160
2019149
2018136