Institution
Vikram Sarabhai Space Centre
Facility•Thiruvananthapuram, 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 published on a yearly basis
Papers
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TL;DR: The seasonality and mutual dependence of aerosol optical properties and cloud condensation nuclei (CCN) activity under varying meteorological conditions at the high-altitude Nainital site (2km) in the Indo-Gangetic Plains were examined using nearly year-round measurements (June 2011 to March 2012) at the Atmospheric Radiation Measurement mobile facility as part of the Regional Aerosol Warming Experiment-Ganges Valley aerosol Experiment of the Indian Space Research Organization and the U.S. Department of Energy as mentioned in this paper.
Abstract: The seasonality and mutual dependence of aerosol optical properties and cloud condensation nuclei (CCN) activity under varying meteorological conditions at the high-altitude Nainital site (2km) in the Indo-Gangetic Plains were examined using nearly year-round measurements (June 2011 to March 2012) at the Atmospheric Radiation Measurement mobile facility as part of the Regional Aerosol Warming Experiment-Ganges Valley Aerosol Experiment of the Indian Space Research Organization and the U.S. Department of Energy. The results from collocated measurements provided enhanced aerosol scattering and absorption coefficients, CCN concentrations, and total condensation nuclei concentrations during the dry autumn and winter months. The CCN concentration (at a supersaturation of 0.46) was higher during the periods of high aerosol absorption (single scattering albedo (SSA) 0.85), indicating that the aerosol composition seasonally changes and influences the CCN activity. The monthly mean CCN activation ratio (at a supersaturation of 0.46) was highest (>0.7) in late autumn (November); this finding is attributed to the contribution of biomass-burning aerosols to CCN formation at high supersaturation conditions.
36 citations
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TL;DR: In this article, the vibration behavior of uniform beams on a two-parameter elastic foundation with initial stress was studied using the finite element formulation, and the results were presented for simply supported and clamped beams with various values for foundation parameters and load parameters.
36 citations
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TL;DR: In this paper, two schemes are presented to generate the compatibility conditions for the integrated force method of discrete analysis, which bypasses the popular concepts of redundants and basis determinate structure of the flexibility method.
Abstract: Two schemes are presented to generate the compatibility conditions for the integrated force method of discrete analysis. In the first scheme (recommended for analysis) the compatibility conditions are generated from the deformation-displacement relationship of the structure. This generation bypasses the popular concepts of redundants and basis determinate structure of the flexibility method. In the second scheme (recommended for design application), the compatibility conditions are obtained as a solution to a linear program (LP), in which the equilibrium equations are the constraints, and the linearized internal energy of the structure is the objective function. The LP is solved taking advantage of the sparsity of the coefficient matrix. The merits and limitations of the two schemes are compared to available procedures in the literature. As examples we take frame structures and plates.
36 citations
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TL;DR: In this article, a two-stage copolymerization of phenol with N-(4-hydroxyphenyl)maleimide (HPM) and formaldehyde in the presence of an acid catalyst is presented.
Abstract: Phenolic resins bearing varying concentrations of phenyl maleimide functions were synthesized by copolymerizing phenol with N-(4-hydroxyphenyl)maleimide (HPM) and formaldehyde in the presence of an acid catalyst. The resins underwent a two-stage curing, through condensation of methylol groups and addition polymerization of maleimide groups. The cure characterization of the resin by dynamic mechanical analysis confirmed the two-stage cure and the dominance of maleimide polymerization over methylol condensation in the network buildup process. The kinetics of both cure reactions, studied by the Rogers method, substantiated the earlier proposed cure mechanism for each stage. Although the initial decomposition temperature of the cured resin was not significantly improved, enhancing the crosslink density through HPM improved thermal stability of the material in a higher temperature regime. The anaerobic char yield also increased proportional to the maleimide content. Isothermal pyrolysis and analysis of the char confirmed that pyrolysis occurs by loss of hydrocarbon and nitrogenous products. The resins serve as effective matrices in silica- and glass fabric–reinforced composites whose mechanical properties are optimum for moderately crosslinked resins, in which failure occurs through a combination of fiber debonding and resin fracture. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 80: 1664–1674, 2001
35 citations
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TL;DR: In this paper, the authors present the results from intensive measurements of refractory BC ( rBC) carried out over Bhubaneswar, an urban site in the eastern coast of India, which experiences contrasting air masses(the IGP outflow or coastal/marine air masses) in different seasons.
Abstract: . Over the Indian region, aerosol absorption is considered to have a potential
impact on the regional climate, monsoon and hydrological cycle. Black carbon
(BC) is the dominant absorbing aerosol, whose absorption potential is
determined mainly by its microphysical properties, including its
concentration, size and mixing state with other aerosol components. The
Indo-Gangetic Plain (IGP) is one of the regional aerosol hot spots with
diverse sources, both natural and anthropogenic, but still the information
on the mixing state of the IGP aerosols, especially BC, is limited and a
significant source of uncertainty in understanding their climatic
implications. In this context, we present the results from intensive
measurements of refractory BC ( rBC ) carried out over Bhubaneswar, an urban
site in the eastern coast of India, which experiences contrasting air masses
(the IGP outflow or coastal/marine air masses) in different seasons. This
study helps to elucidate the microphysical characteristics of BC over this
region and delineates the IGP outflow from the other air masses. The
observations were carried out as part of South West Asian Aerosol Monsoon
Interactions (SWAAMI) collaborative field experiment during July 2016–May 2017, using a single-particle soot photometer (SP2) that uses a
laser-induced incandescence technique to measure the mass and mixing state
of individual BC particles and an aerosol chemical speciation monitor (ACSM)
to infer the possible coating material. Results highlighted the distinctiveness
in aerosol microphysical properties in the IGP air masses. BC mass
concentration was highest during winter (December–February) ( ∼ 1.94 ± 1.58 µ g m −3 ), when the prevailing air masses were
mostly of IGP origin, followed by post-monsoon (October–November) (mean
∼ 1.34 ± 1.40 µ g m −3 ). The mass median diameter
(MMD) of the BC mass size distributions was in the range 0.190–0.195 µ m, suggesting mixed sources of BC, and, further, higher values
( ∼ 1.3–1.8) of bulk relative coating thickness (RCT) (ratio of
optical and core diameters) were seen, indicating a significant fraction of
highly coated BC aerosols in the IGP outflow. During the pre-monsoon
(March–May), when marine/coastal air masses prevailed, BC mass concentration
was lowest ( ∼ 0.82 ± 0.84 µ g m −3 ), and larger
BC cores (MMD > 0.210 µ m) were seen, suggesting distinct
source processes, while RCT was ∼ 1.2–1.3, which may translate
into higher extent of absolute coating on BC cores, which may have crucial
regional climate implications. During the summer monsoon (July–September),
BC size distributions were dominated by smaller cores (MMD ≤ 0.185 µ m), with the lowest coating indicating fresher BC, likely from
fossil fuel sources. A clear diurnal variation pattern of BC and RCT was
noticed in all the seasons, and daytime peak in RCT suggested enhanced
coating on BC due to the condensable coating material originating from
photochemistry. Examination of submicrometre aerosol chemical composition
highlighted that the IGP outflow was dominated by organics (47 %–49 %), and
marine/coastal air masses contained higher amounts of sulfate (41 %–47 %),
while ammonium and nitrate were seen in minor amounts, with significant
concentrations only during the IGP air mass periods. The diurnal pattern of
sulfate resembled that of the RCT of rBC particles, whereas organic mass
showed a pattern similar to that of the rBC mass concentration. Seasonally,
the coating on BC showed a negative association with the mass concentration
of sulfate during the pre-monsoon season and with organics during the
post-monsoon season. These are the first experimental data on the mixing state
of BC from a long time series over the Indian region and include new
information on black carbon in the IGP outflow region. These data help in
improving the understanding of regional BC microphysical characteristics and
their climate implications.
35 citations
Authors
Showing all 2111 results
Name | H-index | Papers | Citations |
---|---|---|---|
M. Santosh | 103 | 1344 | 49846 |
Sabu Thomas | 102 | 1554 | 51366 |
S. Suresh Babu | 70 | 498 | 17113 |
K. Krishna Moorthy | 54 | 263 | 9749 |
Sathianeson Satheesh | 53 | 172 | 11099 |
M. Y. Hussaini | 49 | 207 | 16794 |
J.R. Banerjee | 44 | 146 | 5620 |
C. P. Reghunadhan Nair | 37 | 181 | 4825 |
K. N. Ninan | 36 | 159 | 4156 |
Anil Bhardwaj | 35 | 230 | 4527 |
Ivatury S. Raju | 33 | 121 | 6626 |
Venkata Sai Kiran Chakravadhanula | 32 | 102 | 3011 |
P.K. Sinha | 32 | 118 | 2918 |
J.-P. St.-Maurice | 31 | 113 | 3446 |
Subramaniam Gopalakrishnan | 28 | 123 | 2951 |