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Bhattacharya, K.

Publications and source records attributed to Bhattacharya, K..

9 records
All sourcesNASA NTRSDOE OSTI
DOE OSTI2024

High Char Yield and Flowable Preceramic Resin Enabled with the Monomer Functionalized SiC Particle

Ceramic matrix composites (CMCs) are used in diverse high temperature applications; however, manufacturing CMCs is highly time consuming and costly. We address this challenge by introducing a methodology for fabricating CMCs using an innovative composite preceramic resin. This composite resin contains 40% mass loading of SiC particles, which are chemically functionalized with a resin monomer. The functionalization facilitates a homogenous dispersion of SiC particles within the resin matrix, resulting in high char yield (83.6%) and enhanced impregnation efficiency through reduced melt viscosity, ~10 Pa.s for relevant shear rates. This breakthrough represents a significant stride towards developing a more economically viable and efficient manufacturing process for CMCs.

14 SOLAR ENERGY↗
NASA NTRS1982

Internal variability of an energy-balance model with delayed albedo effects

A simple, deterministic energy-balance model with possible relevance to climatic variations on the time scale of glaciation cycles, is presented. The lag between ice-sheet extent and zonally-averaged temperature is modeled as a time delay in the ice-albedo feedback. The model exhibits self-sustained oscillations which are quasi-periodic or aperiodic in character. Fourier spectra of solutions have the features of many paleoclimatic records: peaks of variable height and width superimposed on a continuous, red-noise type background.

Bhattacharya, K.↗
NASA NTRS1979

An energy-balance model of glaciation cycles

A one dimensional energy balance model is presented which contains a time lagged albedo to account for the delayed dependence of continental ice sheets on temperature; it also includes a smoothing of temperature gradients in the tropics to account for the effect of the Hadley circulation on the strong flattening of meridional temperature profiles there. The model exhibits finite amplitude, sustained free oscillations; these oscillations are triggered by a change in the insulation parameter and occur in the absence of any external forcing. This model behavior strongly suggests the possibility of an almost-intransitive mechanism playing a role in glaciation cycles. This behavior also occurs on shorter time scales which might be relevant to the interannual variability of the atmosphere.

Ghil, M.↗
NASA NTRS1979

An energy-balance model with multiply-periodic and quasi-chaotic free oscillations

A slightly modified version of the one-dimensional time-dependent energy-balance climate model of Ghil and Bhattacharya (1978) is presented. The albedo-temperature parameterization has been reformulated and the smoothing of the temperature distribution in the tropics has been eliminated. The model albedo depends on time-lagged temperature in order to account for finite growth and decay time of continental ice sheets. Two distinct regimes of oscillatory behavior which depend on the value of the albedo-temperature time lag are considered.

Bhattacharya, K.↗