Improved control strategy of DFIG-based wind turbines using direct torque and direct power control techniques

This paper presents different control strategies for a variable-speed wind energy conversion system (WECS), based on a doubly fed induction generator. Direct Torque Control (DTC) with Space-Vector Modulation is used on the rotor side converter. This control method is known to reduce the fluctuations of the torque and flux at low speeds in contrast to the classical DTC, where the frequency of switching is uncontrollable. The reference for torque is obtained from the maximum power point tracking technique of the wind turbine. For the grid-side converter, a fuzzy direct power control is proposed for the control of the instantaneous active and reactive power. Simulation results of the WECS are presented to compare the performance of the proposed and classical control approaches.Peer reviewedFinal Accepted Versio

WILL COUNTRY-OF-ORIGIN LABELING (COOL) BE 'COOL' FOR THE U.S. MEAT INDUSTRY?

The study develops a Muth-type equilibrium displacement model that is able to estimate impacts of COOL on multistage beef production system and its trade relations. The model includes equilibrium conditions of each production stage with consideration of trade and market structure. A unique feature of this model is that it allows for retailer's oligopsony power separately from processor's market power. Simulation results indicate that the cost of COOL would outweigh the overall industry benefit unless COOL leads to low cost increases and more than a 10% increase in consumers' willingness to pay. The COOL provision is expected to have relatively smaller negative impact on cow-calf producers, backgrounders, and feedlots than on packers and retailers.International Relations/Trade,

A Review and Comparison of Ship Power Simulation Methods

Safe, secure and efficient clean sea shipping proposed by the IMO requires the development of the appropriate design, operating knowledge and tools for assessing energy efficient design and operation of ships. A brief overview of the methods and models of ship power management simulation shows the advantages and disadvantages of representative models. This review includes a comparison of different simulation methods, which implies different models, with the aim of optimizing the production of electricity on board, emission reductions and improved energy efficiency. In addition, the recommended technical solution for contributing to energy efficiency on board is given

Social Science and the District Court: The Observation of a Journeyman Trial Judge

The main objective of the thesis is to implement different architectures of 16-bit adders such as; Ripple CarryAdder (RCA), Manchester Carry Chain Adder (MCCA) and Kogge Stone Adder (KSA), in 65nm CMOS technology and to study their performance in terms of power, operating frequency and speed at near threshold operating regions. The performance of these adders are evaluated and compared with each other and a final conclusion is made as to which adder structure is more suitable for implementation in a 65nmtechnology for low power applications. Several optimisation techniques are performed for the adders to reduce the delay and power consumption. Propagation delay is the most critical or essential parameter to be considered, hence, to minimise the delay of the adder, a technique called sizing and ordering are required for the transistors. The purpose of the thesis is to make a fair comparison among adders over several metrics which include linearity, delay and power. Simulation results of MCCA achieved a greater significant performance upon or over RCA and KSA, and proved it is the best suitable adder for low power applications

Communicating over Filter-and-Forward Relay Networks with Channel Output Feedback

Relay networks aid in increasing the rate of communication from source to destination. However, the capacity of even a three-terminal relay channel is an open problem. In this work, we propose a new lower bound for the capacity of the three-terminal relay channel with destination-to-source feedback in the presence of correlated noise. Our lower bound improves on the existing bounds in the literature. We then extend our lower bound to general relay network configurations using an arbitrary number of filter-and-forward relay nodes. Such network configurations are common in many multi-hop communication systems where the intermediate nodes can only perform minimal processing due to limited computational power. Simulation results show that significant improvements in the achievable rate can be obtained through our approach. We next derive a coding strategy (optimized using post processed signal-to-noise ratio as a criterion) for the three-terminal relay channel with noisy channel output feedback for two transmissions. This coding scheme can be used in conjunction with open-loop codes for applications like automatic repeat request (ARQ) or hybrid-ARQ.Comment: 15 pages, 8 figures, to appear in IEEE Transactions on Signal Processin