Magnetic field induced topological nodal-lines in triplet excitations of frustrated antiferromagnet CaV4_4O9_9

Magnetic field induced multiple non-Dirac nodal-lines are found to emerge in the triplet dispersion bands of a frustrated spin-1/2 antiferromagnetic model on the CaVO lattice. Plaquette and bond operator formalisms have been employed to obtain the triplet plaquette and bond excitations for two different parameter regimes in the presence of nearest and next-nearest-neighbor Heisenberg interactions based on the plaquette-resonating-valence-bond and dimerized ground states, respectively. In the absence of magnetic field a pair of six-fold degenerate nodal-loops with distinct topological feature is noted in the plaquette excitations. They are found to split into three pairs of two-fold degenerate nodal-loops in the presence of magnetic field. In the other parameter regime, system hosts two-fold degenerate multiple nodal-lines with a variety of shapes in the triplon dispersion bands in the presence of magnetic field. Ground state energy and spin gap have been determined additionally for the two regimes. Those nodal-lines are expected to be detectable in neutron scattering experiment on the frustrated antiferromagnet, CaV$_4$O$_9$.Comment: 15 pages, 17 figure

Thermally stable multipartite entanglements in the frustrated Heisenberg hexagon

Thermally stable quantum states with multipartite entanglements led by frustration are found in the antiferromagnetic spin-1/2 Heisenberg hexagon. The model has been solved exactly to obtain all analytic expressions of eigenvalues and eigenfunctions. Detection and characterizations for various types of entanglements have been carried out in terms of concurrence and entanglement witnesses based on several thermodynamic observables. Variations of entanglement properties with respect to temperature and frustration are discussed. Even though the frustration opposes the bipartite entanglement, it favors the multipartite entanglement. Entangled states exhibit robustness against the thermal effects in the presence of frustration and they are found to survive at any temperature.Comment: 25 pages, double space, single column, 5 figure

Optimal Solution of a Fully Fuzzy Linear Fractional Programming Problem by Using Graded Mean Integration Representation Method

In the present paper, the study of fully fuzzy linear fractional programming problem (FFLFPP) using graded mean integration representation method is discussed where all the parameters and variables are characterized by trapezoidal fuzzy numbers. A computational algorithm has been presented to obtain an optimal solution by applying simplex method. To demonstrate the applicability of the proposed approach, one numerical example is solved. Also to check the efficiency and feasibility of the proposed approach, we compare the results of examples by applying crisp numbers, triangular fuzzy numbers and trapezoidal fuzzy numbers

Economic Growth and Human Development in Indian States after two decades of Economic Reforms

This paper examines the relative performance of 28 major Indian states over the two decades (1990-2010) on economic growth and human development indicators by empirically confirming the two-way nexus between economic growth (EG) and human development (HD) and identifying other important links in the relationship from cross-sectional growth regressions. The paper finds a strong and consistent convergence in indicators of human development across states even as incomes have diverged over the two decades. Further, the classification of the states into vicious, virtuous, HD-lopsided and EG-lopsided categories and the shifts across categories of different states over the two decades reveal the importance of the requirement of simultaneous thrust on EG and HD in order to escape the vicious cycle

Economic Growth and Human Development in Indian States after two decades of Economic Reforms

This paper examines the relative performance of 28 major Indian states over the two decades (1990-2010) on economic growth and human development indicators by empirically confirming the two-way nexus between economic growth (EG) and human development (HD) and identifying other important links in the relationship from cross-sectional growth regressions. The paper finds a strong and consistent convergence in indicators of human development across states even as incomes have diverged over the two decades. Further, the classification of the states into vicious, virtuous, HD-lopsided and EG-lopsided categories and the shifts across categories of different states over the two decades reveal the importance of the requirement of simultaneous thrust on EG and HD in order to escape the vicious cycle

Essays in information acquisition and decision-making

This thesis analyses two research questions related to information acquisition and consequent decision-making, using theoretical insights and experimental data. It is typically assumed that majority voting is an effective way of aggregating information. Chapter 1 asks if this is true when voters first need to acquire information from sources of different quality and cost? The answer to this question may depend on the ‘transparency’ regime in which voting happens, i.e., how much voters know about others’ information choice and content. Theoretically, more transparent regimes should improve effective information aggregation through voting. We construct a model which shows that less transparent regimes can perform equally well if all group-members vote according to the information they receive. However, when less informed members abstain, a Pareto inferior swing voter’s curse (SVC) equilibrium exists. We conduct a lab experiment to test whether players’ choices are consistent with either of these two equilibria. We compare four regimes with varying levels of transparency between subjects. Our results in less transparent regimes are consistent with SVC equilibrium predictions, under which majority voting does not yield efficient outcomes, as it does in more transparent regimes where individuals always vote based on available information. In sum, we present the first experimental evidence regarding the effect of varying levels of transparency, on endogenous information acquisition, voting and payoffs. Threshold uncertainty has been previously shown to impede the efficient provision of threshold public goods. Chapter 2 asks whether groups perform better when their members reduce uncertainty by acquiring information on the location of the threshold? We conduct an online experiment on threshold public good provision where participants can simultaneously choose to buy private clues about the location of the threshold. Each group contains two low-risk and two high-risk members who differ in their expected loss from failing to reach the threshold. We find that groups reach the threshold less frequently when group members can acquire information than when no information acquisition is possible. We attribute this to low contributions and excessive free riding by those who do not buy information. Further, it is the low-risk members who are disproportionately responsible for this failure of collective action. Our findings show that giving individuals a possibility to learn via private information acquisition can worsen the problem of threshold uncertainty

CONTROL OF VOLTAGE SOURCE INVERTER FOR ADJUSTABLE SPEED DRIVE- A STUDY REPORT

*Author for Correspondence A voltage source inverter (VSI) is commonly used to supply a three-phase induction motor with variable frequency and variable voltage for variable speed applications. Pulse Width Modulation (PWM) Control technique is an excellent control strategy to control various parameters in an induction motor. A number of Pulse width modulation (PWM) schemes are used to obtain variable voltage and frequency supply. The most widely used PWM schemes for three-phase voltage source inverters are carrier-based sinusoidal PWM and space vector PWM (SVPWM). In PWM, three phase reference modulating signals are compared against a common triangular carrier to generate the PWM signals for the three phases. In SVPWM methods, a revolving reference voltage vector is provided as voltage reference instead of three phase modulating waves. There is an increasing trend of using space vector PWM (SVPWM) because of their easier digital realization and better dc bus utilization. The Space Vector Pulse Width Modulation of a three level inverter provides the additional advantage of superior harmonic quality and larger undermodulation range that extends the modulation factor to 90.7 % from the traditional value of 78.5 % in Sinusoida