Home Gardening

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Tomatoes for Canning

PDF pages: 3

Refractive index - Particle density nonequilibrium cesium plasmas probed by a multifrequency helium-neon laser

Refractive index computation for free electrons and neutral atoms in cesium plasma at helium neon laser wavelength

Computer-acquired performance map of an etched-rhenium, niobium planar diode

Computer acquired performance map of etched-rhenium, niobium planar diod

Investigation on the impact of design wind speed and control strategy on the performance of fixed-pitch variable-speed wind turbines

Wind turbine blade design optimization remains one of the fundamental research areas for modern wind turbine technology. The general design process for fixed-pitch variablespeed wind turbine blades assumes the rated wind speed as the design wind speed. However, for a fixed-pitch wind turbine with fixed rotor diameter and rated power at rated speed, we do not know the optimum design wind speed, which should be used for the calculation of the wind turbine blade parameters based on a particular aerofoil for a specific site with low annual mean wind speed. This paper investigates the impact of design wind speed and control strategy on the performance of fixed-pitch wind turbines through a set of design case studies. The design wind speeds are considered at the more prevalent wind speeds than the rated wind speed. Three different control strategies are addressed, i.e. maximum power point tracking, mixture of variable-speed and fixed-speed, and over-speeding. Annual energy production, blade manufacturing cost, aerodynamic load performance and cost of energy are analyzed and compared using the design case studies. The results reveal a clear picture in determining the optimum design wind speed and control strategy for both maximizing annual energy production and minimizing cost of energy

Design and Finite Element Analysis of Mixed Aerofoil Wind Turbine Blades

Wind turbine technology is one of the rapid growth sectors of renewable energy all over the world. As a core component of a wind turbine, it is a common view that the design and manufacturing of rotor blades represent about 20% of the total investment of the wind turbine [1]. Moreover, the performance of a wind turbine is highly dependent on the design of the rotor [2]. As well as rotor aerodynamic performance, the structure strength, stiffness and fatigue of the blade are also critical to the wind turbine system service life. This paper presents the design and Finite Element Analysis (FEA) of a 10KW fixed-pitch variable-speed wind turbine blade with five different thickness of aerofoil shape along the span of the blade. The main parameters of the wind turbine rotor and the blade aerodynamic geometry shape are determined based on the principles of the blade element momentum (BEM) theory. Based on the FE method, deflections and strain distributions of the blade under extreme wind conditions are numerically predicted. The results indicate that the tip clearance is sufficient to prevent collision with the tower, and the blade material is linear and safe

The Importance of Exotic Forage Germplasm in Feeding New Zealand\u27s Livestock

A number of recent reports in New Zealand have expressed the view that restricted access to new plant genetic material from overseas is a major risk to the future growth of the primary sector (MAF, 2002; Douglas, 2003). The restrictions outlined in this paper are the result of the Hazardous Substances and New Organisms (HSNO) Act and regulations administered by MAF and the Environmental Risk Management Authority (ERMA) since July 1998. This paper reviews the historical role of exotic forage germplasm in plant improvement in New Zealand, and quantifies the current contribution of recently imported plant material to exports from the pastoral sector

Comparison of computer-acquired performance data from several fixed spaced planar diodes

Comparison of performance data envelopes for thermionic diodes with various tungsten or rhenium emitters and niobium or molybdenum collector