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Search Results: 1 - 10 of 198160 matches for " N. Sahadev "
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Spectral evolution in a Shastry-Sutherland lattice, HoB(4)
D. Biswas,N. Sahadev,G. Adhikary,G. Balakrishnan,K. Maiti
Physics , 2013, DOI: 10.1103/PhysRevB.88.134405
Abstract: We studied the electronic structure of a Shastry-Sutherland lattice system, HoB4 employing high resolution photoemission spectroscopy and ab initio band structure calculations. The surface and bulk borons exhibit subtle differences, and loss of boron compared to the stoichiometric bulk. However, the surface and bulk conduction bands near Fermi level are found to be similar. Evolution of the electronic structure with temperature is found to be similar to that observed in a typical charge-disordered system. A sharp dip is observed at the Fermi level in the low temperature spectra revealing signature of antiferromagnetic gap. Asymmetric spectral weight transfer with temperature manifests particle-hole asymmetry that may be related to the exotic properties of these systems.
Surface bulk differences in a conventional superconductor, ZrB(12)
S. Thakur,D. Biswas,N. Sahadev,P. K. Biswas,G. Balakrishnan,K. Maiti
Physics , 2013, DOI: 10.1063/1.4817415
Abstract: We studied the electronic structure of a conventional superconductor, ZrB(12) using high resolution x-photoemission spectroscopy and single crystalline samples. Experimental results with different bulk sensitivity reveals boron deficiency and different valence states of Zr at the surface relative to the bulk. Signature of a satellite features is observed in the Zr core level spectra corresponding to the bulk of the material suggesting importance of electron correlation among the conduction electrons in the bulk while the surface appears to be uncorrelated. These results provide an insight in fabricating devices based on such superconductors.
Anomaly in the electronic structure of a BCS superconductor, ZrB(12)
S. Thakur,D. Biswas,N. Sahadev,P. K. Biswas,G. Balakrishnan,K. Maiti
Physics , 2013,
Abstract: We investigate the electronic structure of a complex conventional superconductor, ZrB12 employing high resolution photoemission spectroscopy and ab initio band structure calculations. The experimental valence band spectra could be described reasonably well within the local density approximation. Energy bands close to the Fermi level possess t_(2g) symmetry and the Fermi level is found to be in the proximity of quantum fluctuation regime. The spectral lineshape in the high resolution spectra is complex exhibiting signature of a deviation from Fermi liquid behavior. A dip at the Fermi level emerges above the superconducting transition temperature that gradually grows with the decrease in temperature. The spectral simulation of the dip and spectral lineshape based on a phenomenological self energy suggests a finite electron pair lifetime and a pseudogap above the superconducting transition temperature.
Electronic structure of CaFe2As2
G. Adhikary,D. Biswas,N. Sahadev,R. Bindu,N. Kumar,S. K. Dhar,A. Thamizhavel,K. Maiti
Physics , 2013, DOI: 10.1063/1.4869397
Abstract: We investigate the electronic structure of CaFe$_2$As$_2$ using high resolution photoemission spectroscopy. Experimental results exhibit three energy bands crossing the Fermi level making hole pockets around the $\Gamma$-point. Temperature variation reveal a gradual shift of an energy band away from the Fermi level with the decrease in temperature in addition to the spin density wave (SDW) transition induced Fermi surface reconstruction of the second energy band across SDW transition temperature. The hole pocket in the former case eventually disappears at lower temperatures while the hole Fermi surface of the third energy band possessing finite $p$ orbital character survives till the lowest temperature studied. These results reveal signature of a complex charge redistribution among various energy bands as a function of temperature that might be associated to the exotic properties of this system.
Software Team Skills on Software Product Quality
Viji Vinod,J. Dhanalakshmi,Sunil Sahadev
Asian Journal of Information Technology , 2012,
Abstract: This study provides, an analysis of the skills of the software development team and its effect on the quality of the final software product. An approach for assessing software development team skill and experience is derived from a workforce management tool currently in use by the national aeronautics and space administration. Using data from 220 small scale software development projects based in India and US, the team skill measures are correlated to five software product quality metrics from the ISO/IEC 9126 software engineering product quality standard. An attempt is made in this research to analyze the composition of the development team in terms of personality and in the light of team dynamics. The results indicate that development team skill is a significant factor in product development and project management of the software development. In addition, the results imply that inexperienced software developers are tasked with responsibilities ill suited to their skill level and thus have a significant adverse effect on the quality of the software product.
On Covering a Solid Sphere with Concentric Spheres in ${\mathbb Z}^3$
Sahadev Bera,Partha Bhowmick,Bhargab B. Bhattacharya
Computer Science , 2014,
Abstract: We show that a digital sphere, constructed by the circular sweep of a digital semicircle (generatrix) around its diameter, consists of some holes (absentee-voxels), which appear on its spherical surface of revolution. This incompleteness calls for a proper characterization of the absentee-voxels whose restoration will yield a complete spherical surface without any holes. In this paper, we present a characterization of such absentee-voxels using certain techniques of digital geometry and show that their count varies quadratically with the radius of the semicircular generatrix. Next, we design an algorithm to fill these absentee-voxels so as to generate a spherical surface of revolution, which is more realistic from the viewpoint of visual perception. We further show that covering a solid sphere by a set of complete spheres also results in an asymptotically larger count of absentees, which is cubic in the radius of the sphere. The characterization and generation of complete solid spheres without any holes can also be accomplished in a similar fashion. We furnish test results to substantiate our theoretical findings.
On Chord and Sagitta in ${\mathbb Z}^2$: An Analysis towards Fast and Robust Circular Arc Detection
Sahadev Bera,Shyamosree Pal,Partha Bhowmick,Bhargab B. Bhattacharya
Computer Science , 2014,
Abstract: Although chord and sagitta, when considered in tandem, may reflect many underlying geometric properties of circles on the Euclidean plane, their implications on the digital plane are not yet well-understood. In this paper, we explore some of their fundamental properties on the digital plane that have a strong bearing on the unsupervised detection of circles and circular arcs in a digital image. We show that although the chord-and-sagitta properties of a real circle do not readily migrate to the digital plane, they can indeed be used for the analysis in the discrete domain based on certain bounds on their deviations, which are derived from the real domain. In particular, we derive an upper bound on the circumferential angular deviation of a point in the context of chord property, and an upper bound on the relative error in radius estimation with regard to the sagitta property. Using these two bounds, we design a novel algorithm for the detection and parameterization of circles and circular arcs, which does not require any heuristic initialization or manual tuning. The chord property is deployed for the detection of circular arcs, whereas the sagitta property is used to estimate their centers and radii. Finally, to improve the accuracy of estimation, the notion of restricted Hough transform is used. Experimental results demonstrate superior efficiency and robustness of the proposed methodology compared to existing techniques.
Use and Handling Practice of Pesticides in Vegetables: A Case Study on Some Selected Districts of Nepal
Pramod Koirala,Ananda Shova Tamrakar,Bishnu Prasad Bhattarai,Birendra Kumar Yadav,Sahadev Humagain,Yubak Dhoj GC
Journal of Food Science and Technology Nepal , 2010, DOI: 10.3126/jfstn.v6i0.8270
Abstract: A study was carried out to explore the present status of pesticides use and its handling practices on commercially grown vegetable pockets area of five districts namely; Tanahu, Chitwan, Kavre, Dhading and Bhaktapur of Nepal. Farmers were found to be using 24 types of pesticides in vegetables. The majority of used pesticides were moderately hazardous group of WHO classification. The analyses results revealed that the pesticides residues in vegetables were not detected below the level of 0.007 mg/kg by GLC and below the level of 0.05mg/kg by Test-kit method. However, the handling practice of pesticides among farmers was not found as per the recommended procedure. Additionally, farmers were not aware of using personal protective equipments as well as taking adequate precautions during mixing, spraying and disposal of empty containers. Thus, awareness training to farmers on the use and handling of pesticides was assessed for pest management. J. Food Sci. Technol. Nepal, Vol. 6 (105-109), 2010 DOI: http://dx.doi.org/10.3126/jfstn.v6i0.8270
Evidence of the influence of magnetism on pseudogap states in the high resolution spectra of EuFe$_2$As$_2$
Ganesh Adhikary,Nishaina Sahadev,Deep Narayan Biswas,R. Bindu,Neeraj Kumar,A. Thamizhavel,S. K. Dhar,Kalobaran Maiti
Physics , 2012,
Abstract: Employing {\it state of the art} high resolution photoemission spectroscopy, we studied the temperature evolution of the electronic structure of EuFe$_2$As$_2$, an unique pnictide, where antiferromagnetism of Eu layer survives within the superconducting phase due to `FeAs' layers achieved via substitution and/or pressure. High energy and angle resolution helped to reveal pseudogap-quasiparticle features having primarily As 4$p$ character and spin density wave transition induced band folding in the electronic structure. A weakly dispersing feature of dominant As 4$p$ character is discovered around 80 meV that becomes weaker in intensity below 20 K manifesting influence of antiferromagnetic order on conduction electrons. These results provide an evidence of a link between the pseudogap states and magnetism that could be revealed employing high resolutions.
Interplay of electron correlation and covalency in FeTe(0.6)Se(0.4)
Ganesh Adhikary,Deepnarayan Biswas,Nishaina Sahadev,Swetarekha Ram,V. Kanchana,C. S. Yadav,P. L. Paulose,Kalobaran Maiti
Physics , 2013, DOI: 10.1063/1.4827192
Abstract: We investigate the electronic structure of FeTe(0.6)Se(0.4) employing high resolution photoemission spectroscopy and ab initio band structure calculations. Fe 2p core level and the valence band spectra exhibit signature of strong electron correlation in the electronic structure. The electronic states near the Fermi level reduces in intensity with the decrease in temperature in conformity with the insulating transport observed near 300 K. The observation of an insulator to metal transition around 150 K in the transport properties may be related to the spectral lineshape change in the vicinity of the Fermi level observed in this study. The spectral features near Fermi level exhibit significant p orbital character due to the correlation induced Fe d spectral weight transfer. The experimental spectra reveal dominant temperature dependence of the spectral functions possessing large p-character. These results demonstrate significant renormalization of the character of the conduction electrons due to electron correlation and emphasizes the importance of ligand states in the superconductivity of these materials.
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