1,877 research outputs found
A generalized processor sharing approach to flow control in integrated services networks
No full textThesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1992.Includes bibliographical references (leaves 161-163).by Abhay Kumar J. Parekh.Ph.D
Minimizing the number of clusters in mobile packet radio networks
No full textThesis (M.S.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 1986.MICROFICHE COPY AVAILABLE IN ARCHIVES AND ENGINEERINGBibliography: leaves 82-83.by Abhay Kumar Parekh.M.S
STRENGTHENING DECENTRALIZATION - Augmenting the Consolidated Fund of the states by th Thirteenth Finacnce Commission: A NORMATIVE APPROACH
No full textOne of the terms of reference of the Thirteenth Finance Commission (ThFC) calls upon the Finance Commission to look at ‘Measures needed to augment the consolidated fund of a State to supplement the resources of the Panchayats and Municipalities in the State on the basis of the recommendations made by the Finance Commission of the State’. In view of this, the present study examines issues related to fiscal federalism at the third tier in general and grants to local bodies in particular. It is well documented in the literature that the state of finances of local bodies, both urban and rural, displays a dismal picture in India. In contrast, the finances of the Central and State Governments are on a healthier track with the implementation of the rule based fiscal framework. The study opines that there is a need to fine tune the micro design of grants for local bodies (both urban and local) and their devolution across the States.
ELECTRIC VEHICLE WIRELESS CHARGING SYSTEM WITH VEHICLE-TO-HOME CAPABILITIES
No full textWireless Power Transfer (WPT) is a method that has been developed for about two decades to charge the battery pack in electric vehicles (EVs). It behaves convenient features: that charge EVs by a WPT system occurs without any physical contact. As power transfer takes place by magnetic coupling between two coils: which are placed under the road surface and onboard the vehicle. Therefore, with respect to wired EV charging, such a solution is more reliable as there are no connected items (cables, plugs and sockets), hence, there is no exposition of the connection items to the environment; moreover, it is more friendly, safe and secure as there are no plugs to insert, no cables on the sidewalk and much less chance of vandalism.
The different challenges that are currently with the electric power grid impose in terms of a synergistic, progressive, dynamic, and stable integration of electric mobility. Their solution is through a bidirectional power flow system through EVs. In order to put these factors into a coherent framework for vehicle electrification in this thesis. The key contributions include the following areas: i) Grid-to-Vehicle, ii) Vehicle-to-Grid iii) Home-to-Vehicle, iv) Vehicle-to-Home, v) V2H Uninterruptible power supply have been discussed.
The step-by-step mathematical design of all the converters and coil system takes place as per the SAE J2954 for EVs and Low Voltage grid according to CEI 0-02, for bidirectional wireless system for V2H (BWV2H) application. On this basis, the input and output specifications for the BWV2H can be designated. Subsequently, the active power involved at each conversion stage is calculated by the corresponding maximum current and voltage. This allows factors to determine the rating power of each power converter and of the passive elements arranging the BWV2H. The power sizings are of two different arrangements of BWV2H i.e., secondary in a chopper with cascade to the diode rectifier and a straightforward manner through the active rectifier was discussed.
The thesis continues with the study and analysis of converter losses at different stages together with the series-series (S-S) compensating coils, via two distinct approaches to control the power converters. The operation of converters in SAHFWPT and DAHFWPT are controlled by the extended phase shift and dual phase shift methods respectively. Moreover, in this study, I analyzed the operation and losses of the uni-directional power flow of the WPT system, i.e., from the DC bus on the primary side to the battery load on the secondary side. The loss estimation includes high frequency switching losses, conduction losses, hard turn on and turn off losses coil losses, etc. Finally the efficiency of both arrangement are compared with respect to the internal phase shift angle of converters or input power.
Further, study is to review the effects of the different states of the control between primary and secondary H-bridge converters in WPT. However, in this arrangement the power regulated, in terms of active and reactive power takes place by changing external phase shift angle between both H-bridge by using DPS modulation method. It seems that the controller can work with a wide range of active and reactive power setups. Its helped in eliminate hard switching with small amount of reactive power drawn from source.
Finally, it includes discussion that control algorithms for BWV2H system only with the primary and secondary active H-bridge converter for battery charger. Its focuses on the power conversion stages that are needed for a charging work and grid synchronization at home. The algorithms are built one by one in the continuous time domain using techniques based on the analysis of Bode diagrams of the transfer functions involved in the operation of the system. Using simulations made in the Matlab/Simulink environment, each algorithm's performance has been checked on its own.Wireless Power Transfer (WPT) is a method that has been developed for about two decades to charge the battery pack in electric vehicles (EVs). It behaves convenient features: that charge EVs by a WPT system occurs without any physical contact. As power transfer takes place by magnetic coupling between two coils: which are placed under the road surface and onboard the vehicle. Therefore, with respect to wired EV charging, such a solution is more reliable as there are no connected items (cables, plugs and sockets), hence, there is no exposition of the connection items to the environment; moreover, it is more friendly, safe and secure as there are no plugs to insert, no cables on the sidewalk and much less chance of vandalism.
The different challenges that are currently with the electric power grid impose in terms of a synergistic, progressive, dynamic, and stable integration of electric mobility. Their solution is through a bidirectional power flow system through EVs. In order to put these factors into a coherent framework for vehicle electrification in this thesis. The key contributions include the following areas: i) Grid-to-Vehicle, ii) Vehicle-to-Grid iii) Home-to-Vehicle, iv) Vehicle-to-Home, v) V2H Uninterruptible power supply have been discussed.
The step-by-step mathematical design of all the converters and coil system takes place as per the SAE J2954 for EVs and Low Voltage grid according to CEI 0-02, for bidirectional wireless system for V2H (BWV2H) application. On this basis, the input and output specifications for the BWV2H can be designated. Subsequently, the active power involved at each conversion stage is calculated by the corresponding maximum current and voltage. This allows factors to determine the rating power of each power converter and of the passive elements arranging the BWV2H. The power sizings are of two different arrangements of BWV2H i.e., secondary in a chopper with cascade to the diode rectifier and a straightforward manner through the active rectifier was discussed.
The thesis continues with the study and analysis of converter losses at different stages together with the series-series (S-S) compensating coils, via two distinct approaches to control the power converters. The operation of converters in SAHFWPT and DAHFWPT are controlled by the extended phase shift and dual phase shift methods respectively. Moreover, in this study, I analyzed the operation and losses of the uni-directional power flow of the WPT system, i.e., from the DC bus on the primary side to the battery load on the secondary side. The loss estimation includes high frequency switching losses, conduction losses, hard turn on and turn off losses coil losses, etc. Finally the efficiency of both arrangement are compared with respect to the internal phase shift angle of converters or input power.
Further, study is to review the effects of the different states of the control between primary and secondary H-bridge converters in WPT. However, in this arrangement the power regulated, in terms of active and reactive power takes place by changing external phase shift angle between both H-bridge by using DPS modulation method. It seems that the controller can work with a wide range of active and reactive power setups. Its helped in eliminate hard switching with small amount of reactive power drawn from source.
Finally, it includes discussion that control algorithms for BWV2H system only with the primary and secondary active H-bridge converter for battery charger. Its focuses on the power conversion stages that are needed for a charging work and grid synchronization at home. The algorithms are built one by one in the continuous time domain using techniques based on the analysis of Bode diagrams of the transfer functions involved in the operation of the system. Using simulations made in the Matlab/Simulink environment, each algorithm's performance has been checked on its own
Hydrogeochemical investigation and groundwater quality assessment of Pratapgarh district, Uttar Pradesh
No full textGIS based evaluation of fluoride contamination and assessment of fluoride exposure dose in groundwater of a district in Uttar Pradesh, India
No full textThe Baci
No full textTwo articles concerning the ceremony of the baci in Lao culture. Includes a copy of a book chapter written by Thao Nhouy Abhay, the former Minister of Education.The baci is an expression of welcome. The scanned book pages are from "Kingdom of Laos: The Land of the Million Elephants and of the White Parasol" edited by Rene de Berval; Saigon: France-Asie, 195
Assessment of Mine Water Quality Using Heavy Metal Pollution Index in a Coal Mining Area of Damodar River Basin, India
No full textAssessment of Hydrogeochemical Processes and Mine Water Suitability for Domestic, Irrigation, and Industrial Purposes in East Bokaro Coalfield, India
No full textHydrogeochemical characterization and groundwater quality assessment in a coal mining area, India
No full textThe present study determines major and trace element chemistry of groundwater in the West Bokaro coalfield to assess the hydrogeochemical processes and groundwater quality for drinking and irrigation uses. For this urpose, 33 groundwater samples from different mining areas of the West Bokaro coalfield were collected and analysed for pH, electrical conductivity (EC), total dissolved solid (TDS), dissolved silica (SiO2), major cations (Ca2+, Mg2+, Na+, K+), anions (F−, Cl−, HCO3−, SO42− and NO3−) and trace metals (Mn, Cu, Pb,Zn, Ni, Co, As, Se, Al, Cd, Cr, Ba and Fe). The analytical results show the slightly acidic to alkaline nature of groundwater and dominance of HCO3− and SO42− in anionic and Ca2+ and Na+ in cationic abundance. High SO42− concentrations are attributed to the oxidative weathering of pyrite and gypsum dissolution. Supersaturation condition with respect to dolomite and calcite for most samples may result from the dissolution of gypsum after the water is saturated with respect to the carbonate minerals. The data plot on the Gibbs and Piper diagrams revealed that the groundwater chemistry is mainly controlled by rock weathering with secondary contribution from anthropogenic sources. In a majority of the groundwater samples, alkaline earth metals exceed alkalies and strong acids dominate over weak acid. Ca-Mg-HCO3, Ca-Mg-SO4-Cl and Ca-Mg-SO4 were the dominant hydrogeochemical facies. A comparison of groundwater quality parameters in relation to specified limits for drinking water shows that the concentrations of TDS, SO42−, NO3−, total hardness (TH), Fe and Ni are exceeding the desirable limits in many groundwater samples. Quality assessment for irrigation uses reveal that the groundwater is of good to suitable category. Higher salinity and magnesium hazard values at some sites restrict the suitability of groundwater for irrigation purposes
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