122 research outputs found
The impact of two tier producer and consumer food pricing in India
No full textIndia's government procures agricultural products such as rice, wheat, and sugar at below-market prices and sells them in both urban and rural ration shops. The rest of such crops is sold in the open market. This creates a two-tier price system for consumers and producers. Many (including Dantwala, Mellor, and Hayami, Subbarao, and Otsuka) claim that such a policy raises the open-market price so much that it ultimately increases the average price received by farmers. Iftrue, the gainers would be the farm sector as a whole and low-income urban consumers with access to the ration shops. Losers would be the high-income urban consumers who buy at the open-market price. This view has provided an intellectual basis for the policy. The author examines a variety of cases: with and without rationing, with rationing by ration cards or by queuing, with and without the urban rich having access to the ration shops, with and without free trade, and with a marketable surplus with positive, negative, or zero price elasticity. He finds that in most cases the policy's impact on the average price is either negative or ambiguous, and it is negative in the more realistic cases. A negative impact implies that farmers on the whole lose from the procurement policy. But small farmers who are net buyers of the procured crops, and landless laborers, gain from a lower average price in the short run (especially if they have easy access to the rural ration shops). The long-run effect depends on the impact of the lower average price on rural employment and wages.Markets and Market Access,Economic Theory&Research,Environmental Economics&Policies,Consumption,Access to Markets
Robust statistics over Riemannian manifolds for computer vision
No full textThe nonlinear nature of many compute vision tasks involves analysis over curved nonlinear spaces embedded in higher dimensional Euclidean spaces. Such spaces are known as manifolds and can be studied using the theory of differential geometry. In this thesis we develop two algorithms which can be applied over manifolds.
The nonlinear mean shift algorithm is a generalization of the original mean shift, a popular feature space analysis method for vector spaces. Nonlinear mean shift can be applied to any Riemannian manifold and is provably convergent to the local maxima of an appropriate kernel density. This algorithm is used for motion segmentation with different motion models and for the filtering of complex image data.
The projection based M-estimator is a robust regression algorithm which does not require a user supplied estimate of the scale, the level of noise corrupting the inliers. We build on the connections between kernel density estimation and robust M-estimators and develop data driven rules for scale estimation. The method can be generalized to handle heteroscedastic data and subspace estimation. The results of using pbM for affine motion estimation, fundamental matrix estimation and multibody factorization are presented.
A new sensor fusion method which can handle heteroscedastic data and incomplete estimates of parameters is also discussed. The method is used to combine image based pose estimates with inertial sensors.Ph.D.Includes bibliographical references (p. 137-144)
A Novel Hybrid Control Strategy and Dynamic Performance Enhancement of a 3.3 kW GaN–HEMT-Based iL2C Resonant Full-Bridge DC–DC Power Converter Methodology for Electric Vehicle Charging Systems
No full textThe conventional resonant inductor–inductor–capacitor (L2C) DC–DC converters have the major drawbacks of poor regulation, improper current sharing, load current ripples, conduction losses, and limiting the power levels to operate at higher loads for electric vehicle (EV) charging systems. To address the issues of the L2C converter, this paper proposes an interleaved inductor–inductor–capacitor (iL2C) full-bridge (FB) DC–DC converter as an EV charger with wide input voltage conditions. It comprises two L2C converters operating in parallel on the primary side with 8-GaN switches and maintains the single rectifier circuit on the secondary side as common. Further, it introduces the hybrid control strategy called variable frequency + phase shift modulation (VFPSM) technique for iL2C with a constant voltage charging mode operation. The design requirements, modeling, dynamic responses, and operation of an iL2C converter with a controller are discussed. The analysis of the proposed concept designed and simulated with an input voltage of 400 Vin at a load voltage of 48 V0 presented at different load conditions, i.e., full load (3.3 kW), half load (1.65 kW), and light load (330 W). The dynamic performances of the converter during line and load regulations are presented at assorted input voltages. In addition, to analyze the controller and converter performance, the concept was validated experimentally for wide input voltage applications of 300–500 Vin with a desired output of 48 V0 at full load condition, i.e., 3.3 kW and the practical efficiency of the iL2C converter was 98.2% at full load
Analysis of a Modified Switching Pattern for Packed U Cell-15 Inverter Topology with Advanced Level Shift Carrier Pulse Width Modulation Techniques
No full textdesign considerations for developing electric vehicle charging stations
No full textIn recent years, it is seen that there has been a huge expansion in the electric vehicles market aiming to reduce the impact of greenhouse gases. The deployment of an optimal and cost-effective electric vehicle charging stations similar to petrol/diesel stations with advanced control algorithms is necessary for the successful implementation. This review paper gives an overview of electric vehicles and various configurations about the design aspects of charging station. The charging stations are categorized on the basis of power utilized with various optimization algorithms, methods and future directions are presented to have an optimal design. And also, the
highlights of grid connected combination of renewable energy based and grid connected, off-grid mode are summarized along with the future scope. Incorporation of renewable energy along with storage systems in the charging station can reduce the high load taken from the grid especially at peak times. By providing an overview of these key areas, the review study aims to provide a deep insight to the industry experts and researchers for
future developments
DSP based current controlled single stage single phase integrated converter with external compensating signal for Class-C & Class-D appliances
No full textFuzzy peak current controlled integrated PFC convert-er with slope compensation
No full textThis propounded a novel method of design and implementation of a fuzzy peak current mode (PCM) controlled Buck Integrated Power Factor Correction (PFC) Converter with compensation ramp. It derives its advantages through low buck capacitor voltage and single control switch, which leads to reduced complex control and price. Sub-harmonic oscillations generates in peak current controller can be nullified by using ramp signal, there by improves the overall performance of the converter. The fuzzy controller (FLC) robust and effective than conventional linear controllers like P, PI, PID, hence in this work a (90 – 265V), 50Hz AC, 48V DC and 100 kHz frequency converter is implemented in MATLAB/Simulink software and results are presented. Results show that converter meets international regularity commission regulations.</jats:p
DSP based current controlled single stage single phase integrated converter with external compensating signal for Class-C & Class-D appliances
No full textDesign and implementation of a current controlled single stage single phase integrated AC/DC isolated Power Factor Correction (PFC) converter is presented in this paper. With the integrated topology reduces the number control switches. The proposed converter has the advantage of low bulk capacitor voltage and only single control switch hence reduce in complexity in control and cost. Sub-harmonic oscillations which are produced in conventional current controller. By adding an external compensating signal effect of oscillations are reduced and performance of the converter is improved. The proposed scheme is implemented in real time by TMS320F2812 digital signal processor (DSP) board. The performance of converter is verified both experimentally and by simulation at different load and line conditions. The proposed converter is designed for 90–230 V, 50 Hz AC input, 48 V DC output and operating at 100 kHz switching frequency. The Experimental results shows that the DSP-based fuzzy controlled single phase single switch integrated PFC converter achieve high power factor and satisfies IEC-61000-3-2 and other European input current harmonic limits for Class-C & Class-D applications
Fuzzy LPCM controlled buck integrated PFC convert-er for Class-C&D appliances
No full textThis propounded a novel method of design and implementation of a fuzzy linear peak current mode (LPCM) controlled Buck Integrated Power Factor Correction (PFC) Converter. It derives its advantages through low buck capacitor voltage and single control switch, which leads to reduced complex control and price. Sub-harmonic oscillations generates in peak current controller can be nullified by using ramp signal, there by improves the overall performance of the converter. The fuzzy controller (FLC) robust and effective than conventional linear controllers like P, PI, PID, hence in this work a (90 – 265V), 50Hz AC, 48V DC and 100 kHz frequency converter is implemented in MATLAB/Simulink software and results are verified experimentally. Results show that converter meets international regularity commission regulations.</jats:p
Effect of Surface Active Agents in Boiling Heat Transfer
No full textTitle: Effect of Surface Active Agents in Boiling Heat Transfer, Author: Subbarao N. Rao, Location: ThodeThe boiling heat transfer phenomenon has presented a state o ambiguity regarding the role of solid-liquid-vapour interface in the mechanisms of heat transfer. Recent studies (S1, M1) have given an indication to the possibility of the vaporization of a micro layer at the boiling surface as a alternative to the well known theories based purely on the hydrodynamic factors. This study is an attempt to understand the boiling heat transfer mechanism at solid-liquid-vapour interface and to study the effect of interfacial properties like surface tension and contact angle on the maximum (critical) heat flux. The present studies use the technique of changing the solid-liquid-vapour interface characteristics of water through the use of surface-active agent as additive, to study the boiling heat transfer under changed interface conditions. Four different surfactants were used at three levels of concentration in water. Surface tension and contact angle measurements were carried out using the shadow photographs of pendant cops and sessile drops. Boiling heat flux measurements of these surfactant solutions in water were carried out using heat transfer surface. Experiments involving pool boiling and the boiling of thin liquid films were carried out over the transition and nucleate boiling regimes. It has been observed that the solid-liquid-vapour interface characteristics play a cry important role in the boiling heat transfer mechanism. By a suitable choice type of surfactant and concentration, the critical heat flux and heat transfer coefficients can be improved markedly. It is suggested that the spreading wetting characteristic improves the heat transfer rate whereas the increased viscosity and decreased thermal conductivity of the liquid microlayer under the vapour masses may cause the heat flux to decrease. The present study shows significant possibilities for future studies in the nucleate boiling, transition boiling and film boiling regimes using surfactant solutions.ThesisMaster of Engineering (ME
- …
