Very low frequency radio astronomy has considerable astrophysical importance. But its development comes up with significant methodological and instrumental difficulties. It is evident that many of them can be overcome by creating low frequency radio telescopes outside of the Earth ionosphere. However the giant size of the effective area needed for many astrophysical tasks especially below 30 MH...

this work is focused on synthesis of sio2- cnt hybrides via sol-gel method. homogeneous distribution of carbon nanotubes within silicon matrix was obtained by mixing the functionalized carbon nanotube (cntcooh) with active silicic acid followed by titration to the solution of sodium silicate (na2sio3) under the average temperature condition of 80?c. different ratios of multi-walled carbon nanot...

Gaps created by falling trees (tree-fall gaps) are a natural disturbance in forest ecosystems. Understanding scale, pattern and the effect of gaps on regeneration is important to current and future forest management. The aim of this study was to determine the size, shape and the spatial pattern of tree-fall gaps and of associated regeneration. This study was carried out in three parcels (No.15,...

Bird-window collisions cause an estimated one billion bird deaths annually in the United States. Building characteristics and surrounding habitat affect collision frequency. Given the importance of collisions as an anthropogenic threat to birds, mitigation is essential. Patterned glass and UV-reflective films have been proven to prevent collisions. At Duke University's West campus in Durham, No...

This study proposes a hybrid renewable energy system consisting of photovoltaic panels and wind turbine to supply the total or part demand grid-connected residential building presents optimal size using genetic algorithm. Wind speed, solar irradiance, electricity are monitored in 15 min intervals over year. It is found that values for PV panels’ area, rated power turbine, tower height 148.5 m2,...