Performance of an Ocean Energy Conversion System with DFIG Sensorless Control

The 2009/28/EC Directive requires Member States of the European Union to adopt a National Action Plan for Renewable Energy. In this context, the Basque Energy Board, EVE, is committed to research activities such as the Mutriku Oscillating Water Column plant, OWC. This is an experimental facility whose concept consists of a turbine located in a pneumatic energy collection chamber and a doubly fed induction generator that converts energy extracted by the turbine into a form that can be returned to the network. The turbo-generator control requires a precise knowledge of system parameters and of the rotor angular velocity in particular. Thus, to remove the rotor speed sensor implies a simplification of the hardware that is always convenient in rough working conditions. In this particular case, a Luenberger based observer is considered and the effectiveness of the proposed control is shown by numerical simulations. Comparing these results with those obtained using a traditional speed sensor, it is shown that the proposed solution provides better performance since it increases power extraction in the sense that it allows a more reliable and robust performance of the plant, which is even more relevant in a hostile environment as the ocean.

Problems of industrial fisheries development in the Cross River State

The industrial fisheries as opposed to artisanal fisheries in Cross River State, Nigeria, is discussed, considering the prospect of industrial fisheries in the State and identifying the major fish and shrimp resources within the coastal waters. Industrial fishing was introduced in 1973 when the state government invited a Japaneese company to carry out a joint exploratory shrimp fishing venture. The contributions made by the Seastate Seafoods Company, the Eyib's Nutritional Food and the Arawak Fishing Companies towards the increase in the number of fishing fleet in the state are noted.

Heat Transfer of Aviation Kerosene at Supercritical Conditions

The heat transfer characteristics of China no. 3 kerosene were investigated experimentally and analytically under conditions relevant to a regenerative cooling system for scramjet applications. A test facility developed for the present study can handle kerosene in a temperature range of 300-1000 K, a pressure range of 2.6-5 MPa, and a mass How rate range of 10-100 g/s. In addition, the test section was uniquely designed such that both the wall temperature and the bulk fuel temperature were measured at the same location along the flowpath. The measured temperature distributions were then used to analytically deduce the local heat transfer characteristics. A 10-component kerosene surrogate was proposed and employed to calculate the fuel thermodynamic and transport properties that were required in the heat transfer analysis. Results revealed drastic changes in the fuel flow properties and heat transfer characteristics when kerosene approached its critical state. Convective heat transfer enhancement was also found as kerosene became supercritical. The heat transfer correlation in the relatively low-fuel-temperature region yielded a similar result to other commonly used jet fuels, such as JP-7 and JP-8, at compressed liquid states. In the high-fuel-temperature region, near and beyond the critical temperature, heat transfer enhancement was observed; hence, the associated correlation showed a more significant Reynolds number dependency.

The economic impact of diseases and parasitic problems in freshwater fish production

Diseases and parasitic problems could constitute significant economic losses in fish production if not controlled, thus the need to continue monitoring its prevalence. Based on field studies on feral and intensively raised fish at the Kainji Lake Research Institute Nigeria, some diseases and parasitic problems have been identified. These include; helminthiasis; fungal disease; protozoa which include Myxosoma sp., Myxobolus spp., Henneguya sp., Trichodina sp., Ichthopthrius sp. bacterial mainly Aeromonas sp., Pseudomonas sp., mechanical injuries; death due to unknown causes and economic assessment of myxosporidian infection. Suggestion for disease control in fish production are recommended

Prospects and problems of rice-fish culture in Nigeria

This paper examines fish demand and supply and looks at on-going research works in rice-cum-fish culture in Nigeria. It examines all the pre-requisites for adopting this farming system. Economic and Financial analysis were made using experimental plots at two ecological zones of Nigeria. This farming system, which has reached advanced stage in most of Asian countries, could well be practiced in Nigeria to assist farmers to harvest both protein (from fish) and carbohydrate from rice and thereby to improve their standards of live

Problems and prospects of community-based resource management approach: an experience with the implementation of the ban on beach seines on Lake Kainji

Community Based Resource Management (CBRM) understood as an approach emphasizes a community's capability, responsibility and accountability with regards to managing resources. Based on the recommendations for the Nigerian-German Kainji Lake Fisheries Promotion Project (KLFPP), the Niger and Kebbi States Fisheries Edicts were promulgated in 1997. These edicts, among other things, banned the use of beach seines. Given the conviction of KLFPP, that if communities whose livelihood is linked to the fishery, understand and identify the problems and by consensus agree to the solutions of fisheries problems, they are more likely to adhere to any control measures, specifically the ban on beach seine. In 1999 a first agreement was reached between beach seiners, non-beach seiners and government authorities leading to an almost complete elimination of beach seine on the Lake Kainji. However, despite on going efforts of the Kainji Lake Fisheries Management and Conservation Unit in 2000 and possibly because of certain oversights during and after the first agreement, in May 2001 a significant number of beach seiners was observed. This led to a re-assessment of our approach, which lately culminated into another round of negotiation. The paper presents the latest results on this on-going process

Adaptive Scalable SVD Unit for Fast Processing of Large LSE Problems

Singular Value Decomposition (SVD) is a key linear algebraic operation in many scientific and engineering applications. In particular, many computational intelligence systems rely on machine learning methods involving high dimensionality datasets that have to be fast processed for real-time adaptability. In this paper we describe a practical FPGA (Field Programmable Gate Array) implementation of a SVD processor for accelerating the solution of large LSE problems. The design approach has been comprehensive, from the algorithmic refinement to the numerical analysis to the customization for an efficient hardware realization. The processing scheme rests on an adaptive vector rotation evaluator for error regularization that enhances convergence speed with no penalty on the solution accuracy. The proposed architecture, which follows a data transfer scheme, is scalable and based on the interconnection of simple rotations units, which allows for a trade-off between occupied area and processing acceleration in the final implementation. This permits the SVD processor to be implemented both on low-cost and highend FPGAs, according to the final application requirements.