The calibration coefficients of several models of cup and propeller anemometers were analysed. The analysis was based on a series of laboratory calibrations between January 2003 and August 2007. Mean and standard deviation values of calibration coefficients from the anemometers studied were included. Two calibration procedures were used and compared. In the first, recommended by the Measuring Network of Wind Energy Institutes (MEASNET), 13 measurement points were taken over a wind speed range of 4 to 16 ms" 1 . In the second procedure, 9 measurement points were taken over a wider speed range of 4 to 23 m s _1. Results indicated no significant differences between the two calibration procedures applied to the same anemometer in terms of measured wind speed and wind turbines' Annual Energy Production (AEP). The influence of the cup anemometers' design on the calibration coefficients was also analysed. The results revealed that the slope of the calibration curve, if based on the rotation frequency and not the anemometer's output frequency, seemed to depend on the cup center rotation radius.
The alula is a high-lift device located at the leading edge of bird wings that allows these animals to fly at large angles of attack and low speeds without wing stalling. The influence of the alula in the wing aerodynamics seems to be similar to that of leading-edge slats in aircraft wings. Aiming to clarify the role of the alula in the aerodynamics of the bird wings, the aerodynamic forces generated by a model simulating the wing of a pigeon equipped with different alulae were measured in a wind tunnel. Experimental results show that alula deflection causes the boundary layer to remain attached at large values of the angle of attack (at least in the wing area protected by this device: from the alula position to the wing root), so that lift forces can be up to 22 per cent higher than those measured at the same angle of attack without alula deflection.
EUSO-TA is a on-ground telescope, installed at the Telescope Array (TA) site in Black Rock Mesa, Utah, USA in 2013. The main aim of the project is observation of Ultra High Energy Cosmic Rays (UHECR) through detection of ultraviolet light generated by cosmic-ray showers. EUSO-TA consists of two, 1 m 2 square Fresnel lenses with a field of view of about 10.6 • × 10.6 •. Light is focused on the Photo Detector Module (PDM), identical to the ones that are employed in the other EUSO missions' focal surfaces. The PDM is composed of 36 Hamamatsu multi-anode photomultipliers (64 channels per tube), for a total of 2304 channels. Front-End readout is performed by 36 ASICS, with trigger and readout tasks done by two acquisition boards that send the data to a CPU and storage system. The telescope is housed in a shed located in front of one of the fluorescence detectors of the TA experiment, pointing in the direction of the Electron Light Source and Central Laser Facility. After the installation in February 2013, the performance of the detector has been very good, with little (about one photoelectron) electronic noise and a Point Spread Function of stars compatible with expectations. Several ultra high energy cosmic rays and meteors have been observed. The limiting magnitude of 5.5 on summed frames has been established, with PSF of ∼ 2.5 pixels FWHM. Measurements of the UV background in different darkness conditions and moon phases and positions have been completed. EUSO-TA has been used for development of balloon and space flights within the EUSO framework.
EUSO-Balloon is a pathfinder mission for the Extreme Universe Space Observatory onboard the Japanese Experiment Module (JEM-EUSO). It was launched on the moonless night of the 25 th of August 2014 from Timmins, Canada. The flight ended successfully after maintaining the target altitude of 38 km for five hours. One part of the mission was a 2.5 hour underflight using a helicopter equipped with three UV light sources (LED, xenon flasher and laser) to perform an inflight calibration and examine the detectors capability to measure tracks moving at the speed of light. We describe the helicopter laser system and details of the underflight as well as how the laser tracks were recorded and found in the data. These are the first recorded laser tracks measured from a fluorescence detector looking down on the atmosphere. Finally, we present a first reconstruction of the direction of the laser tracks relative to the detector.
JEM-EUSO is a space mission designed to investigate Ultra-High Energy Cosmic Rays and Neutrinos (E > 5 · 10 19 eV) from the International Space Station (ISS). Looking down from above its wide angle telescope is able to observe their air showers and collect such data from a very wide area. Highly specific trigger algorithms are needed to drastically reduce the data load in the presence of both atmospheric and human activity related background light, yet retain the rare cosmic ray events recorded in the telescope. We report the performance in offline testing of the first level trigger algorithm on data from JEM-EUSO prototypes and laboratory measurements observing different light sources: data taken during a high altitude balloon flight over Canada, laser pulses observed from the ground traversing the real atmosphere, and model landscapes reproducing realistic aspect ratios and light 5 conditions as would be seen from the ISS itself. The first level trigger logic successfully kept the trigger rate within the permissible bounds when challenged with artificially produced as well as naturally encountered night sky background fluctuations and while retaining events with general air-shower characteristics.
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