522 research outputs found

    Power Quality Improvement by Using Statcom Control Scheme in Wind Energy Generation Interface to Grid

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    “Electric Power Quality (EPQ) is a term that refers to maintaining the near sinusoidal waveform of power distribution bus voltages and currents at rated magnitude and frequency.” Today customers are more aware of the seriousness that the power quality possesses, this prompts the utilities to assure good quality of power to their customer. The power quality is basically customer-centric. The increased focus on utilities toward to maintaining reliable power supply by employing power quality improvement tools has reduced the power outages and blackout considerably. Good power quality is the characteristic of reliable power supply. Low power factor, harmonic pollution, load imbalance, fast voltage variations are some common parameters which are used to define the power quality. If the power quality issues are not checked, i.e., the parameters that define power quality doesn't fall within the predefined standards than it will lead to high electricity bill, high running cost in industries, malfunctioning of equipments, challenges in connecting renewables. Capacitor banks, FACTS devices, harmonic filters, SVC's, STATCOM are the solutions to achieve the power quality. The performance of Wind turbine generators is affected by poor quality power, at the same time these wind power generating plant affects the power quality negatively. This paper presents the STATCOM system with the BESS and studies the impact on the power quality in a system which consist of wind turbine generator, nonlinear load, hysteresis controller for controlling the operation of STATCOM and grid. The model is simulated in the MATLAB/Simulink. This scheme mitigates the power quality issues, improves voltage profile and also reduces harmonic distortion of the waveforms. BESS level out the imbalances caused by real power due to intermittent nature of wind power available due to varying wind speeds

    Multivariate dynamic information

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    AbstractThis paper develops measures of information for multivariate distributions when their supports are truncated progressively. The focus is on the joint, marginal, and conditional entropies, and the mutual information for residual life distributions where the support is truncated at the current ages of the components of a system. The current ages of the components induce a joint dynamic into the residual life information measures. Our study of dynamic information measures includes several important bivariate and multivariate lifetime models. We derive entropy expressions for a few models, including Marshall–Olkin bivariate exponential. However, in general, study of the dynamics of residual information measures requires computational techniques or analytical results. A bivariate gamma example illustrates study of dynamic information via numerical integration. The analytical results facilitate studying other distributions. The results are on monotonicity of the residual entropy of a system and on transformations that preserve the monotonicity and the order of entropies between two systems. The results also include a new entropy characterization of the joint distribution of independent exponential random variables

    Braiding fractional quantum Hall quasiholes on a superconducting quantum processor

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    Direct experimental detection of anyonic exchange statistics in fractional quantum Hall systems by braiding the excitations and measuring the wave-function phase is an enormous challenge. Here, we use a small, noisy quantum computer to emulate direct braiding within the framework of a simplified model applicable to a thin cylinder geometry and measure the topological phase. Our algorithm first prepares the ground state with two quasiholes. It then applies a unitary operation controlled by an ancilla, corresponding to a sequence of adiabatic evolutions that takes one quasihole around the other. We finally extract the phase of the wave function from measuring the ancilla with a compound error mitigation strategy. Our results open a new avenue for studying braiding statistics in fractional Hall states.Comment: 9 pages, 8 figure

    REGRESSIONS FOR SUMS OF SQUARES OF SPACINGS

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    Abstract. Starting with a new formula for the regression of sum of squares of spacings (SSS) with respect to the maximum we present a characterization of a family of beta type mixtures in terms of the constancy of regression of normalized SSS of order statistics. Related characterization for records describes a family of minima of independent Weibull distributions

    Craniocerebral missile injuries in civilian Kashmir – India

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    Background The missile injuries of the cranium and brain in the modern era have shifted from soldiers to the civilians and from the battle grounds to the populated zones due to increase in the terrorist and military strikes. The management of the victims depends on the resuscitation at the site of injury and the distance and transportation to the tertiary care centre. This article presents the details of the missile injuries to the brain, the third-world problems and the management. Material and methods A retrospective analysis of 3794 craniocerebral missile injuries, managed by the Department of Neurosurgery at Sher-I-Kashmir Institute of Medical Sciences (SKIMS) Kashmir, India, over a period of more than 21 years from September 1988 to September 2009. Patients were triaged in emergency CT-room, resuscitated and operated. Statistical software programme SPSS 11.5 was used to derive the numerical significance. Results Revealed an overall mortality of 87.69% (3327 out of 3794). Most of the deaths 79.14% (2633 out of 3327) occurred within 30 minutes of the patient’s arrival to the hospital and only 694 patients lived beyond one hour of arrival. Conclusion Presently the quantum of outcome i.e, survival and good recovery in craniocerebral missile injuries appears a meager heap compared to the huge amount of death and disability. And the situation will continue to be so unless tertiary care hospitals are set up within and around the armed and conflict zones, war torn areas and battle fields, rather than risking transportation, time of resuscitation, intervention and the results.Key words: Craniocerebral, Kashmir, Missile Injuries, Outcome

    Single view reflectance capture using multiplexed scattering and time-of-flight imaging

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    This paper introduces the concept of time-of-flight reflectance estimation, and demonstrates a new technique that allows a camera to rapidly acquire reflectance properties of objects from a single view-point, over relatively long distances and without encircling equipment. We measure material properties by indirectly illuminating an object by a laser source, and observing its reflected light indirectly using a time-of-flight camera. The configuration collectively acquires dense angular, but low spatial sampling, within a limited solid angle range - all from a single viewpoint. Our ultra-fast imaging approach captures space-time "streak images" that can separate out different bounces of light based on path length. Entanglements arise in the streak images mixing signals from multiple paths if they have the same total path length. We show how reflectances can be recovered by solving for a linear system of equations and assuming parametric material models; fitting to lower dimensional reflectance models enables us to disentangle measurements. We demonstrate proof-of-concept results of parametric reflectance models for homogeneous and discretized heterogeneous patches, both using simulation and experimental hardware. As compared to lengthy or highly calibrated BRDF acquisition techniques, we demonstrate a device that can rapidly, on the order of seconds, capture meaningful reflectance information. We expect hardware advances to improve the portability and speed of this device.National Science Foundation (U.S.) (Award CCF-0644175)National Science Foundation (U.S.) (Award CCF-0811680)National Science Foundation (U.S.) (Award IIS-1011919)Intel Corporation (PhD Fellowship)Alfred P. Sloan Foundation (Research Fellowship

    Paraganglioma of the tongue with SDHB gene mutation in a patient with Graves' disease

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    The authors want to thank Mr. Jose Eduardo Matos (photog-rapher) for his technical assistance.We report a case of an apparently sporadic paraganglioma of the tongue with a germ-line mutation in a female patient with asymptomatic Graves' disease. The tongue is an unusual primary location. Genetic testing is mandatory in all cases. Thyroid gland dysfunction and autoimmune phenomena could be associated with some paragangliomas.S
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