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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 effect of mixing on the extent of pseudoplasticity has been represented in the form of a bar chart and a correlation in terms of shear and yield stresses has been developed for viscosity index.
Abstract: The effect of mixer blade speed and mixing cycle time on the rheological behaviour of an optimized HTPB-based propellant formulations has been studied keeping the temperature constant. Variations in yield stress and viscosity at unit shear rate have been determined as a function of time for different mixing speeds. The effect of mixing on the extent of pseudoplasticity has been represented in the form of a bar chart. A correlation in terms of shear and yield stresses has been developed for viscosity index, i.e., the viscosity at unit shear rate as a function of mixer blade speed.

19 citations

Journal ArticleDOI
TL;DR: Several new polybenzimidazoles (PBIs) and N-phenyl PBIs were synthesized by high temperature solution polycondensation techniques as mentioned in this paper.
Abstract: Several new polybenzimidazoles (PBIs) and N-phenyl PBIs were synthesized by high temperature solution polycondensation techniques. Three different tetramine hydrochlorides and one N-phenyl tetramine hydrochloride were condensed independently with p-phenylenedioxydiacetic acid (PDDA), 2,2′-[isopropylidene bis(p-phenyleneoxy)] diacetic acid (bisacid A2) and 2,2′-[sulfonyl bis(p-phenyleneoxy)] diacetic acid (bisacid S) in polyphosphoric acid (PPA) at high temperatures. The polymers were obtained in 55–65% yield with inherent viscosities in the range 0.58–0.96 dL/g. Four model benzimidazoles (MBI) were also synthesized to confirm the formation of polybenzimidazoles. The PBIs and MBIs were characterized by infrared spectroscopy and elemental analysis. The properties of the polymers such as solubility, density, crystallinity, and thermal, thermoxidative, and isothermal stabilities were studied.

19 citations

Journal ArticleDOI
TL;DR: In this paper, pyrolysis-GC and thermogravimetric data were used to provide partial characterization of the substrates of the MnO2-cured polysulfide polymer.
Abstract: Polymers prepared by curing thiol-terminated liquid polysulfide polymer [HS(RS2)nRSH, R = CH2CH2OCH2OCH2CH2] with p-quinonedioxime, PbO2, and MnO2 were studied by pyrolysis-GC and thermogravimetry. Characteristic differences were observed in the composition of the pyrolyzates under flash pyrolysis at 420 and 470°C. The concentration of the cyclic monomer, 1,3-dioxa-6,7-dithionane, in the pyrolyzates was found to vary considerably from polymer to polymer. The change in mechanism with the extent of degradation and the corresponding overall activation energies were evaluated by thermogravimetry. The pyrolysis-GC and thermogravimetric data were shown to provide partial characterization of the substrates. Mn appears to be in a coordinated complex in the MnO2-cured polymer.

19 citations

Journal ArticleDOI
TL;DR: In this article, the response of ionospheric E-region electric fields and currents to solar flare related X-ray flux enhancements are studied at the magnetic equatorial location of Trivandrum (8.5°N, 77°E; dip 0.6°N) using VHF (54.95 MHz) coherent backscatter radar observations conducted during daytime.
Abstract: The response of ionospheric E-region electric fields and currents to solar flare related X-ray flux enhancements are studied at the magnetic equatorial location of Trivandrum (8.5°N, 77°E; dip 0.5°N) using VHF (54.95 MHz) coherent backscatter radar observations in the altitude region of 95–110 km conducted during daytime. The amplitude of the Solar Flare Effects (SFE) observed in the earth’s magnetic field variations at Trivandrum have been examined in relation to that at Alibag and it is found that the ratio of the SFE amplitudes at the two stations lies in the range of 1.8–2.6. The backscattered power of the VHF radar showed a substantial reduction during the peak phase of all the strong X-rank flares studied. It has also been observed that there is a sharp fall in the ratio of the field line integrated Hall conductivity (σ2) to the field line integrated Pedersen conductivity (σ1) in the dynamo region during strong flare times in relation to normal times. The time variations of mean Doppler frequency (f D ) of the backscattered signals have been observed to indicate a fall close to the peak phase of the strong flare events. Another new result is the radar observed presence of westward electric field for a long duration of 2–3 hours during a partial counter electrojet (CEJ) event that occurred on one of the days (8 July 1992) studied. The implications of the observations are discussed in detail.

19 citations

Journal ArticleDOI
TL;DR: In this paper, a parametric study on variation of coefficient of thermal expansion (α) due to change in fibre orientation of carbon-carbon cap type structure is studied and it is concluded that one of the critical design variables identified is the α value across the thickness of the laminate.
Abstract: Thermo-structural analyses of passive and active hot composite structures considering temperature dependent material properties under thermal and mechanical loads are carried out. The behaviour of the composite material under thermal, thermo-chemical and mechanical loads is studied. A general approach to carry out thermo-structural analysis and how the behaviour is incorporated in the modelling are briefly discussed. Thermo-structural analysis shows that thermal stresses are very much predominant when compared to stresses due to mechanical loads. A parametric study on variation of coefficient of thermal expansion (α) due to change in fibre orientation of carbon–carbon cap type structure is studied and it is concluded that one of the critical design variables identified is the α value across the thickness of the laminate.

19 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