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The design of a stall-regulated wind turbine
to achieve a maximum annual energy output is still a formidable task for engineers.
The design could be carried out using an average wind speed together with a standard
statistical distribution such as a Weibull with k = 2.0. In this study a more elaborated
design will be attempted by also considering the statistical bias as a design criterion.
The wind data used in this study were collected from three areas of the Lamtakong
weather station in Nakhonratchasima Provice, the Khaokoh weather station in Phetchaboon
and the Sirindhorn dam weather station in Ubonratchathani, Thailand. The objective
is to design a best aerodynamic configurations for the blade (chord, twist and pitch)
using the same airfoil as that of NREL Phase VI wind turbine. Such design is carried
out at a design wind speed point. Wind turbine blades were optimized for both maximum
annual energy production and minimum cost of energy using a method that take into
account aerodynamic and structural considerations. The work will be carried out
by the program “SuWiTStat” which was developed by the authors and based on BEM Theory
(Blade Element Momentum). Another side issue is the credibility of the Weibull statistic
in representing the real wind measurement. This study uses a regression analysis
to determine this issue.
In this paper we show how light emitting diodes (LEDs) can be used in conjunction with existing display technologies as a means for achieving ultra-rapid visual stimulus exposure durations. We review existing rapid visual display methods, and show how our apparatus overcomes the limitations inherent with each technique. Our apparatus, the LED tachistoscope, takes advantage of the fast-switching times and high-brightness capabilities of LEDs in order to present stimuli at previously unachievable durations as rapid as 1 ms. The rapid exposure durations are achieved by external LED backlight illumination of images on a liquid crystal display (LCD) after the components of the LCD have stabilized. This ensures that stimulus onset and offset are discrete. Furthermore, the fast-switching of the LEDs enables stimuli to be revealed for very rapid durations. The paper also describes studies in which the LED tachistoscope has already been applied, and offers suggestions for other possible applications. Interestingly, in our studies we show that the human visual system is very adept at extracting information with only very minimal stimulus exposure durations. Such studies have not been possible with existing display equipment. The LED tachistoscope opens up avenues for a variety of psychological and physiological experiments and provides a means for revealing the limits of human visual perception.