Tezpur, India
Tezpur, India

Tezpur University is an Indian Central University located in Tezpur in the North Eastern state of Assam, India by an act in Parliament of India in 1994.The governor of Assam, Janaki Ballabh Patnaik is the chancellor of Tezpur University, Mihir Kanti Chaudhuri is the vice-chancellor and Amarjyoti Choudhury is the pro vice-chancellor. Wikipedia.

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Borah D.,Tezpur University | Dasgupta A.,Jamia Millia Islamia University
Physics Letters, Section B: Nuclear, Elementary Particle and High-Energy Physics | Year: 2015

The Fermi gamma ray space telescope data have pointed towards an excess of gamma rays with a peak around 1-3 GeV in the region surrounding the galactic center. This anomalous excess can be described well by a dark matter candidate having mass in the range 31-40 GeV annihilating into bb pairs with a cross section of (σν)≃(1.4-2.0)×10-26 cm3/s. In this work we explore the possibility of having such a dark matter candidate within the framework of a radiative neutrino mass model. The model is a simple extension of the standard model by an additional U(1)X gauge symmetry where the standard model neutrino masses arise both at tree level as well as radiatively by the anomaly free addition of one singlet fermion NR and two triplet fermions ∑1R, ∑2R with suitable Higgs scalars. The spontaneous gauge symmetry breaking is achieved in such a way which results in a residual Z2 symmetry hence providing a stable cold dark matter candidate. We show that the singlet fermionic dark matter candidate in our model can give rise to the galactic center gamma ray excess. The parameter space which simultaneously satisfies the constraints on relic density, direct detection scattering as well as collider bounds essentially corresponds to an s-wave resonance where the gauge boson mass mX is approximately twice that of dark matter mass mχ. We also discuss the compatibility of such a light fermion singlet dark matter with light neutrino mass. © 2014 The Authors.

Agency: European Commission | Branch: FP7 | Program: CSA-CA | Phase: KBBE.2011.4-05 | Award Amount: 1.92M | Year: 2011

The main objective of the SAHYOG project is to establish a partnering initiative to coordinate research activities carried out in Europe and India on biomass production and biowaste conversion through biotechnological approaches. The integrated project activities will be carried out by a partnership of stakeholders from EU and India involving public and private organizations that conceive and fund research programmes as well as representatives from the scientific community. Strong EU-India linkages will be created between on-going and future research and innovation projects with the aim to exploit cooperation synergies for sustainable development. The project will be based on comprehensive inventories integrating research activities from Europe and India in order to identify common areas of interest as well as knowledge gaps and cooperation opportunities. The twinning of projects and short term exchanges among researchers will be important tools to strengthen collaboration and promote networking in areas of shared strategic interest. Several stakeholder workshops will provide opportunities to explore the opinions and perspectives of European and Indian scientists and R&D programme managers. Thereby, the SAHYOG project will help to identify opportunities for joint initiatives between the EU and its Member States and India in the field of biomass production and biowaste conversion. The organization of conferences and summer schools will contribute to increase the visibility of scientific excellence and the impact of innovation in the sector. Finally, a Strategic Research Agenda and a R&D road map will be developed in order to facilitate concerted planning of future joint EU-India research initiatives Thereby, pathways will be identified to promote new technologies that will drive Europe and India to an increased exploitation of biotechnology for biomass production and biowaste conversion.

Das R.,Tezpur University
International Journal of Heat and Mass Transfer | Year: 2011

An inverse problem is solved for simultaneously estimating the convection-conduction parameter and the variable thermal conductivity parameter in a conductive-convective fin with temperature dependent thermal conductivity. Initially, the temperature field is obtained from a direct method using an analytical approach based on decomposition scheme and then using a simplex search minimization algorithm an inverse problem is solved for estimating the unknowns. The objective function to be minimized is represented by the sum of square of the error between the measured temperature field and an initially guessed value which is updated in an iterative manner. The estimation accuracy is studied for the effect of measurement errors, initial guess and number of measurement points. It is observed that although very good estimation accuracy is possible with more number of measurement points, reasonably well estimation is obtained even with fewer number of measurement points without measurement error. Subject to selection of a proper initial guess, it is seen that the number of iterations could be significantly reduced. The relative sensitiveness of the estimated parameters is studied and is observed from the present work that the estimated convection-conduction parameter contributes more to the temperature distribution than the variable conductivity parameter. © 2011 Elsevier Ltd. All rights reserved.

Borah D.,Tezpur University
Nuclear Physics B | Year: 2013

We study the possibility of generating deviations from tri-bimaximal (TBM) neutrino mixing to explain the non-zero reactor mixing angle within the framework of both type I and type II seesaw mechanisms. The type I seesaw term gives rise to the μ-τ symmetric TBM pattern of neutrino mass matrix as predicted by generic flavor symmetry models like A4 whereas the type II seesaw term gives rise to the required deviations from TBM pattern to explain the non-zero θ13. Considering extremal values of Majorana CP phases such that the neutrino mass eigenvalues have the structure (m1, -m2, m3) and (m1, m2, m3), we numerically fit the type I seesaw term by taking oscillation as well as cosmology data and then compute the predictions for neutrino parameters after the type II seesaw term is introduced. We consider a minimal structure of the type II seesaw term and check whether the predictions for neutrino parameters lie in the 3σ range. We also outline two possible flavor symmetry models to justify the minimal structure of the type II seesaw term considered in the analysis. © 2013 Elsevier B.V.

Dey M.,Tezpur University | Gogoi N.,Tezpur University
Angewandte Chemie - International Edition | Year: 2013

Not just any old iron ion: A linear, two-coordinate ionic FeI complex (see scheme) with a S=3/2 ground state has a large energy barrier for magnetization reversal, Ueff=226 cm-1, and undergoes slow magnetic relaxation in the absence of an applied magnetic field. The preparation of complexes with these properties is a step towards the eventual practical application of single-molecule magnets. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Sahu P.P.,Tezpur University
Applied Optics | Year: 2012

In this paper, we have introduced optically controlled two-mode interference (OTMI) coupler having silicon core and GaAsInP cladding as an all-optical switch. By taking advantage of refractive index modulation by launching optical pulse into cladding region of TMI waveguide, we have shown optically controlled switching operation. We have studied optical pulse-controlled coupling characteristics of the proposed device by using a simple mathematical model on the basis of sinusoidal modes. The device length is less than that of previous work. It is also seen that the cross talk of the OTMI switch is not significantly increased with fabrication tolerances (±δω) in comparison with previous work. © 2012 Optical Society of America.

A detailed quantum chemical study is performed on the unimolecular decomposition reaction of the alkoxy radical, CF3C(O)OCH(O)CF 3 produced from CF3C(O)OCH2CF3, trifluoroethyl trofluoroacetate (TFETFA) at the MPWB1K and M06-2X level of theories using the 6-31+G(d,p) basis set. Five plausible decomposition pathways including reaction with O2, α-ester rearrangement and thermal decomposition (C-C, C-H and C-O bonds scission) have been considered in detail. Out of the five prominent decomposition channels, our results reveal that reaction with O2 is the dominant path for the decomposition of the CF3C(O)OCH(O)CF3 radical in the atmosphere involving the lowest energy barrier which is in accordance with recent experimental findings. Our theoretical results also suggest that α-ester rearrangement leading to the formation of trifluoroacetic acid (TFA) has a negligible contribution for decomposition of the title alkoxy radical. The thermal rate constants for the above decomposition pathways are evaluated using Canonical Transition State Theory (CTST) at 298 K. © 2014 the Partner Organisations.

Majumdar K.C.,Kalyani University | Majumdar K.C.,Tezpur University | Mondal S.,Kalyani University
Chemical Reviews | Year: 2011

Some of the recent developments in the synthesis of fused sultams are discussed. A cascade ring-closure metathesis/isomerization and subsequent radical cyclization was utilized to generate tricyclic sultams from bisallylsulfonamides by Piva and co-workers. de Meijere and co-workers developed a facile synthesis of tricyclic sultams by cycloisomerization of 4,9-diheterododecadienyne followed by intramolecular [4 + 2]-cycloaddition. A synthesis of condensed sultams deriving from intramolecular 1,3-dipolar cycloadditions of nitrones was described by Yamamoto and co-workers. Landry and co-workers reported the synthesis of the tetracyclic N-8-quinolinyl benzenesultam, a novel nuclear factor kappa B (NF-kB) inhibitor. In 2004, Ley and co-workers developed the total synthesis of the cytotoxic antitumor natural product epothilone C by coupling of the three fragments.

Borah D.,Tezpur University
International Journal of Modern Physics A | Year: 2014

We discuss the possible origin of nonzero reactor mixing angle θ13 and Dirac CP phase δCP in the leptonic sector from a combination of type I and type II seesaw mechanisms. Type I seesaw contribution to neutrino mass matrix is of tri-bimaximal (TBM) type which gives rise to vanishing θ13 leaving the Dirac CP phase undetermined. If the Dirac neutrino mass matrix is assumed to take the diagonal charged lepton (CL) type structure, such a TBM type neutrino mass matrix originating from type I seesaw corresponds to real values of Dirac Yukawa couplings in the terms YijL̄iHNj. This makes the process of right-handed heavy neutrino decay into a light neutrino and Higgs (N → νH) CP preserving ruling out the possibility of leptogenesis. Here we consider the type II seesaw term as the common origin of nonzero θ13 and δCP by taking it as a perturbation to the leading order TBM type neutrino mass matrix. First, we numerically fit the type I seesaw term by taking oscillation as well as cosmology data and then compute the predictions for neutrino parameters after the type II seesaw term is introduced. We consider a minimal structure of the type II seesaw term and check whether the predictions for neutrino parameters lie in the 3σ range. We also compute the predictions for baryon asymmetry of the universe by considering type II seesaw term as the only source of CP violation and compare it with the latest cosmology data. © 2014 World Scientific Publishing Company.

Datta D.,Tezpur University
Applied Soft Computing Journal | Year: 2013

The unit commitment problem (UCP) is a nonlinear mixed-integer optimization problem, encountered as one of the toughest problems in power systems. The problem becomes even more complicated when dynamic power limit based ramp rate constraint is taken into account. Due to the inadequacy of deterministic methods in handling large-size instances of the UCP, various metaheuristics are being considered as alternative algorithms to realistic power systems, among which genetic algorithm (GA) has been investigated widely since long back. Such proposals have been made for solving only the integer part of the UCP, along with some other approaches for the real part of the problem. Moreover, the ramp rate constraint is usually discussed only in the formulation part, without addressing how it could be implemented in an algorithm. In this paper, the GA is revisited with an attempt to solve both the integer and real parts of the UCP using a single algorithm, as well as to incorporate the ramp rate constraint in the proposed algorithm also. In the computational experiment carried out with power systems up to 100 units over 24-h time horizon, available in the literature, the performance of the proposed GA is found quite satisfactory in comparison with the previously reported results. © 2013 Elsevier B.V. All rights reserved.

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