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380 results on '"Ghosh, Gautam"'

19. Ferritic Alloys with Extreme Creep Resistance via Coherent Hierarchical Precipitates.

Author

Song, Gian, Sun, Zhiqian, Li, Lin, Xu, Xiandong, Rawlings, Michael, Liebscher, Christian H, Clausen, Bjørn, Poplawsky, Jonathan, Leonard, Donovan N, Huang, Shenyan, Teng, Zhenke, Liu, Chain T, Asta, Mark D, Gao, Yanfei, Dunand, David C, Ghosh, Gautam, Chen, Mingwei, Fine, Morris E, and Liaw, Peter K

Subjects
Biochemistry and Cell Biology, Other Physical Sciences
Abstract

There have been numerous efforts to develop creep-resistant materials strengthened by incoherent particles at high temperatures and stresses in response to future energy needs for steam turbines in thermal-power plants. However, the microstructural instability of the incoherent-particle-strengthened ferritic steels limits their application to temperatures below 900 K. Here, we report a novel ferritic alloy with the excellent creep resistance enhanced by coherent hierarchical precipitates, using the integrated experimental (transmission-electron microscopy/scanning-transmission-electron microscopy, in-situ neutron diffraction, and atom-probe tomography) and theoretical (crystal-plasticity finite-element modeling) approaches. This alloy is strengthened by nano-scaled L21-Ni2TiAl (Heusler phase)-based precipitates, which themselves contain coherent nano-scaled B2 zones. These coherent hierarchical precipitates are uniformly distributed within the Fe matrix. Our hierarchical structure material exhibits the superior creep resistance at 973 K in terms of the minimal creep rate, which is four orders of magnitude lower than that of conventional ferritic steels. These results provide a new alloy-design strategy using the novel concept of hierarchical precipitates and the fundamental science for developing creep-resistant ferritic alloys. The present research will broaden the applications of ferritic alloys to higher temperatures.

Published
2015

23. Mixing and Decoherence to Nearest Separable States

Author

Lahiri, Avijit, Ghosh, Gautam, and Nag, Sankhasubhra

Subjects
Quantum Physics
Abstract

We consider a class of entangled states of a quantum system (S) and a second system (A) where pure states of the former are correlated with mixed states of the latter, and work out the entanglement measure with reference to the nearest separable state. Such `pure-mixed' entanglement is expected when the system S interacts with a macroscopic measuring apparatus in a quantum measurement, where the quantum correlation is destroyed in the process of environment-induced decoherence whereafter only the classical correlation between S and A remains, the latter being large compared to the former. We present numerical evidence that the entangled S-A state drifts towards the nearest separable state through decoherence, with an additional tendency of equimixing among relevant groups of apparatus states., Comment: RevTeX4 document, 20 pages, 7 eps figure files

Published
2008

25. Quantum Chaos: Reduced Density Matrix Fluctuations in Coupled Systems

Author

Nag, Sankhasubhra, Ghosh, Gautam, and Lahiri, Avijit

Subjects
Quantum Physics
Abstract

Following a recent work (briefly reviewed below) we consider temporal fluctuations in the reduced density matrix elements for a coupled system involving a pair of kicked rotors as also one made up of a pair of Harper Hamiltonians. These dynamical fluctuations are found to constitute a reliable indicator of the degree of chaos in the quantum dynamics, and are related to stationary features like the eigenvalue and eigenvector distributions of the system under consideration. A brief comparison is made with the evolution of the reduced distribution function in the classical phase space., Comment: 19 pages, 13 figures, elsart style

Published
2004
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26. Entropy production due to coupling to a heat bath in the kicked rotor problem

Author

Nag, Sankhasubhra, Lahiri, Avijit, and Ghosh, Gautam

Subjects
Quantum Physics
Abstract

Considering a kicked rotor coupled to a model heat bath both the classical and quantum entropy productions are calculated exactly. Starting with an initial wave packet, the von Neuman entropy as a function of time is determined from the reduced density matrix while the Liouville evolution of the corresponding Husimi distribution provides us with the classical entropy. It is found that both these entropies agree reasonably satisfying the same asymptotic growth law and more importantly both are proportional to the classical Liapounov exponent., Comment: 9 pages, 5 .eps figures, Latex

Published
2001
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30. Performance of Direct-Seeded Rice as Influenced by Dual Cropping with Nitrogen Levels and Weed Management Practices in Prayagraj Region of Eastern Uttar Pradesh

Author

Singh, Suryendra, Elamathi, S., Ghosh, Gautam, Anandhi, P., and Masih, Lalita Prakash

Abstract

A field experiment was conducted at Sam Higginbottom University of Agriculture, Technology and Sciences (SHUATS), Prayagraj (U.P.), India, to evaluate the performance of direct-seeded rice (DSR) as influenced by dual cropping with nitrogen levels and weed management practices. Dual cropping of Sesbaniawith 100% recommended dose of nitrogen gave comparable yields with higher net returns and C/B ratio for both the years. Pretilachlor plus (@ 0.3 kg a.i./ha) as pre-emergence application followed by hand-weeding (HW) at 45 days after sowing (DAS) was effective in controlling weeds and increasing yields of DSR which resulted in higher economic returns than HW twice at 20 and 45 DAS. The results showed that farmers could save 56% human labour, 73% machine labour and 25% irrigation water as compared to transplanted rice; thus, DSR technology has the potential to increase farmers’ income and save natural resources.

Published
2024
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