Indian Institute of Technology Bombay

About: Indian Institute of Technology Bombay is a education organization based out in Mumbai, India. It is known for research contribution in the topics: Catalysis & Computer science. The organization has 16756 authors who have published 33588 publications receiving 570559 citations.

Broadband Bent Triangular Omnidirectional Antenna for RF Energy Harvesting

Abstract: In this letter, a broadband bent triangular omnidirectional antenna is presented for RF energy harvesting. The antenna has a bandwidth for ${\hbox {VSWR}}\leq2$ from 850 MHz to 1.94 GHz. The antenna is designed to receive both horizontal and vertical polarized waves and has a stable radiation pattern over the entire bandwidth. Antenna has also been optimized for energy harvesting application and it is designed for $100~\Omega $ input impedance to provide a passive voltage amplification and impedance matching to the rectifier. A peak efficiency of 60% and 17% is obtained for a load of $500~\Omega $ at 980 and 1800 MHz, respectively. At a cell site while harvesting all bands simultaneously a voltage of 3.76 V for open circuit and 1.38 V across a load of $4.3~\hbox{k} \Omega $ is obtained at a distance of 25 m using an array of two elements of the rectenna.

Novel Nonlinear Droop Control Techniques to Overcome the Load Sharing and Voltage Regulation Issues in DC Microgrid

Abstract: In a dc microgrid, good load sharing and voltage regulation are desirable. These are affected by practical factors like sensor calibration errors and cable resistances. To enhance the load-sharing accuracy among the parallel-connected voltage-controlled sources and to improve the dc-bus voltage regulation, three novel nonlinear droop control techniques are proposed for the smart grid scenario. The proposed methods are completely decentralized methods and require only local information (output voltage and output current of the individual converter) for achieving aforementioned merits. Since no communication channel is required, it is easy to implement them. Furthermore, the absence of communication channel improves system reliability and offers plug-and-play features, as only local information is utilized. Also, failure of one converter does not affect the operation of other converters connected to the grid as no information is exchanged between the converters. Effect of sensor calibration errors and cable resistances is minimized by these techniques. Theoretical analysis and experimental results are presented to demonstrate the efficacy of the proposed control methods. Finally, a performance analysis of the three droop control techniques is presented along with their advantages over the conventional methods under different operating conditions.

Origin of spin gapless semiconductor behavior in CoFeCrGa: Theory and Experiment

Abstract: Despite a plethora of materials suggested for spintronic applications, a new class of materials has emerged, namely spin gapless semiconductors (SGS), which offers potentially more advantageous properties than existing ones These magnetic semiconductors exhibit a finite band gap for one spin channel and a closed gap for the other Here, supported by electronic-structure calculations, we report evidence of SGS behavior in equiatomic quaternary CoFeCrGa, having a cubic Heusler (prototype LiMgPdSn) structure but exhibiting chemical disorder (${\mathrm{DO}}_{3}$ structure) CoFeCrGa is found to transform from SGS to half-metallic phase under pressure, which is attributed to unique electronic-structure features The saturation magnetization $({M}_{S})$ obtained at $8\phantom{\rule{016em}{0ex}}\mathrm{K}$ agrees with the Slater-Pauling rule and the Curie temperature $({T}_{C})$ is found to exceed $400\phantom{\rule{016em}{0ex}}\mathrm{K}$ Carrier concentration (up to $250\phantom{\rule{016em}{0ex}}\mathrm{K}$) and electrical conductivity are observed to be nearly temperature independent, prerequisites for SGS The anomalous Hall coefficient is estimated to be $185\phantom{\rule{016em}{0ex}}\mathrm{S}/\mathrm{cm}$ at $5\phantom{\rule{016em}{0ex}}\mathrm{K}$ Considering the SGS properties and high ${T}_{C}$, this material appears to be promising for spintronic applications

Mapping a research area at the micro level using co-word analysis

Abstract: The present study investigates the use of co-word analysis method to understand the micro structure of a research speciality. This study is done in the area of Condensed Matter Physics (CMP) taking two time-periods, 1990 and 1995. Based on concurrent set of journals occurring in the subject heading list of CMP in these two time-periods, a database is created after downloading articles present in these journals from the INSPEC database. Using words extracted from the titles from the created database, suitable co-word pairs are constructed. These words, and co-word pairs are explored further to understand their linkages with each other through network analysis methods. Dynamics, within the CMP across 1990 and 1995, are investigated through the comparison of the words, co-word pairs and structurally equivalent blocks. The results are projected using multi-dimensional scaling. The important conclusions of this study are discussed.

Forward Neutral-Pion Transverse Single-Spin Asymmetries in p + p Collisions at √s = 200 GeV

Abstract: We report precision measurements of the Feynman x (x(F)) dependence, and first measurements of the transverse momentum (p(T)) dependence, of transverse single-spin asymmetries for the production of pi(0) mesons from polarized proton collisions at s=200 GeV. The x(F) dependence of the results is in fair agreement with perturbative QCD model calculations that identify orbital motion of quarks and gluons within the proton as the origin of the spin effects. Results for the p(T) dependence at fixed x(F) are not consistent with these same perturbative QCD-based calculations.