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Search Results: 1 - 10 of 3343 matches for " Chirashree Ghosh "
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Asymmetric Variation in Soil Carbon Emission in Sub-Tropics  [PDF]
Rashmi Kant, Chirashree Ghosh
Atmospheric and Climate Sciences (ACS) , 2012, DOI: 10.4236/acs.2012.21012
Abstract: Carbon dioxide emission from soil, known as soil respiration, is one of the major sources of the atmospheric carbon. Understanding the relationship between emission rate and the factors associated with the emission process is important in global carbon emission management. The present study investigated soil respiration at three ecologically diverse locations in northern India. CO2 emission was measured in-situ by modified alkali absorption method at three different depths, top-soil (0 cm - 2 cm depth), mid-soil (20 cm depth) and deep-soil (40 cm depth) at each location. Rate of carbon emission from soil varied with location and time. The rate was higher at Riverine Zone (RZ) which had high soil moisture content and profuse ground vegetation compared to Hilly Zone (HZ) containing dry soil and scarce vegetation. The emission rate was also greater in grassland than the plantation area. Rate of carbon emission from soil was heterogeneous along different depths below the ground. Diel variation in emission rate was greater at HZ compared to RZ. Higher microbial population in soil was detected in RZ than HZ. However, the bacterial count out-numbered the fungal count in soils at most places. The study indicates a positive relationship between soil respiration rate and microbial abundance. The fungal population was strongly correlated with CO2 emission rate.
Microscopic calculation of proton capture reactions in mass 60-80 region and its astrophysical implications
Chirashree Lahiri,G. Gangopadhyay
Physics , 2011, DOI: 10.1140/epja/i2011-11087-2
Abstract: Microscopic optical potentials obtained by folding the DDM3Y interaction with the densities from Relativistic Mean Field approach have been utilized to evaluate S-factors of low-energy $(p,\gamma)$ reactions in mass 60-80 region and to compare with experiments. The Lagrangian density FSU Gold has been employed. Astrophysical rates for important proton capture reactions have been calculated to study the behaviour of rapid proton nucleosynthesis for waiting point nuclei with mass less than A=80.
Importance of Q-values in astrophysical rp-proces
Chirashree Lahiri,G. Gangopadhyay
Physics , 2013, DOI: 10.1142/S0217732313500764
Abstract: The importance of measuring Q-values in rapid proton capture process has been investigated. The microscopic optical model, derived using a nucleon nucleon interaction and densities from relativistic mean field calculations, has been utilized to calculate the reaction rates. It has been observed that the Q-values involved in the reactions at waiting points at A = 60 and 64 are very important in determining the final abundance of the process. Some other Q-values also play a crucial role in the final abundance of nuclei near the end point of the process.
Relativistic Mean Field in $A\approx$80 nuclei and low energy proton reactions
Chirashree Lahiri,G. Gangopadhyay
Physics , 2011, DOI: 10.1103/PhysRevC.84.057601
Abstract: Relativistic Mean Field calculations have been performed for a number of nuclei in mass $A\approx$80 region. Ground state binding energy, charge radius and charge density values have been compared with experiment. Optical potential have been generated folding the nuclear density with the microscopic nuclear interaction DDM3Y. S-factors for low energy ($p,\gamma$) and ($p,n$) reactions have been calculated and compared with experiment.
Proton dripline in a new formula for nuclear binding energy
Chirashree Lahiri,G. Gangopadhyay
Physics , 2011, DOI: 10.1142/S0218301311020411
Abstract: The location of the proton dripline in a new phenomenological mass formula is calculated. Predictions of different mass formulas for the dripline are compared. The implications of the new mass formula for rapid proton nucleosynthesis beyond $^{56}$Ni are discussed. It is seen that the new formula indicates that masses up to A=80 are easily synthesized in a typical X-ray burst.
Low energy proton reactions of astrophysical interest in A$\sim90-100$ region
Chirashree Lahiri,G. Gangopadhyay
Physics , 2012, DOI: 10.1103/PhysRevC.86.047601
Abstract: Semimicroscopic optical potentials for low energy proton reactions in mass 90-100 region have been obtained by folding the density dependent M3Y interaction with relativistic mean field densities. Certain parameters in the potential have been deduced by comparing calculated results with the data for elastic scattering. Low energy proton reactions in this mass region have been studied in the formalism with success. Rates of important astrophysical reaction in the mass region have been calculated.
Endpoint of $rp$ process using relativistic mean field approach and a new mass formula
Chirashree Lahiri,G. Gangopadhyay
Physics , 2012, DOI: 10.1142/S0218301312500747
Abstract: Densities from relativistic mean field calculations are applied to construct the optical potential and, hence calculate the endpoint of the rapid proton capture ($rp$) process. Mass values are taken from a new phenomenological mass formula. Endpoints are calculated for different temperature- density profiles of various X-ray bursters. We find that the $rp$ process can produce significant quantities of nuclei upto around mass 95. Our results differ from existing works to some extent.
Neutron rich nuclei in a new binding energy formula and the astrophysical $r-$process
Chirashree Lahiri,G. Gangopadhyay
Physics , 2012, DOI: 10.1142/S0218301312500425
Abstract: Neutron rich nuclei has been studied with a new phenomenological mass formula. Predictions of different mass formulas for the location of the neutron dripline are compared with those from the present calculation. The implications of the new mass formula for r-process nucleosynthesis are discussed. It is found that though the neutron drip line obtained from this formula differs substantially from other formulas, the r-process abundance upto mass 200 are unlikely to be significantly different. The errors inherent in the mass formula are found to play an insignificant role beyond mass A = 80.
CFD evaluation of thermal convection inside the DACON convection sensor in actual space flight  [PDF]
Pradyumna Ghosh, M. K. Ghosh
Natural Science (NS) , 2011, DOI: 10.4236/ns.2011.36057
Abstract: A CFD(Computational Fluid Dynamics) model has been developed using the commercial CFD package FLUENT for the thermal convection inside air filled cylindrical DACON sensor, where the onboard time dependent gravitational micro acceleration has been considered. Time dependent, curve fitted gravitational accelera-tion in x- and y-axes from published data have been incorporated in FLUENT through a User Defined Function (UDF), developed in C which includes space craft rotation. At the sensor plane the two-dimensional flow has also been visualized. A good agreement is between simu-lation and published experimental data. Last but not the least, for checking its response to suffi-ciently strong perturbations in an orbital flight, physical and numerical experiments are carried out where an astronaut swung the sensor in hands along the y axis with amplitude of 10cm and a frequency of 0.2 Hz. A good qualitative validation has been achieved between CFD and actual experimental results.
Studies on Synthesis and Characterization of Magnesia Based Refractory Aggregates Developed from Indian Magnesite  [PDF]
Manas Kamal Haldar, Chandrima Ghosh, Arup Ghosh
Journal of Materials Science and Chemical Engineering (MSCE) , 2014, DOI: 10.4236/msce.2014.210001
Abstract:

The present work intends to study the properties of magnesia based refractory aggregates developed from Indian magnesite by changing lime/silica ratio. The material has been sintered in the temperature range of 1550C - 1700C. The sintered samples are characterized in terms of bulk density, apparent porosity, true density, percentage densification, mechanical, thermo-mechanical properties like cold modulus of rupture, hot modulus of rupture and thermal shock resistance and structural properties by XRD. The developed microstructures at different temperatures are studied through FESEM study and compositional analysis of the developed phases is done by EDX study.

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