نتایج جستجو برای: sun
تعداد نتایج: 34548 فیلتر نتایج به سال:
What makes the sun shine? How does the sun produce the vast amount of energy necessary to support life on earth? These questions challenged scientists for a hundred and fifty years, beginning in the middle of the nineteenth century. Theoretical physicists battled geologists and evolutionary biologists in a heated controversy over who had the correct answer. Why was there so much fuss about this...
Public health authorities in the United States are recommending that men, women and children reduce their exposure to sunlight, based on concerns that this exposure will promote skin cancer. On the other hand, data show that increasing numbers of Americans suffer from vitamin D deficiencies and serious health problems caused by insufficient sun exposure. The body of science concerning the benef...
A new genus and two new species of Phygadeuontini (Hymenoptera, Ichneumonidae, Cryptinae) from China
Carinityla Sheng & Sun gen. n., Carinityla punctulata Sheng & Sun sp. n. and Carinityla pilosa Sheng & Sun sp. n. belonging to the tribe Phygadeuontini of the subfamily Cryptinae (Hymenoptera, Ichneumonidae), collected from Jiangxi Province, China, are described. A key to the species of the new genus, Carinityla Sheng & Sun, gen. n., is provided and the genus is placed in Townes' key to genera ...
Over the recent past, the galactic environment of the Sun has differed substantially from today. Sometime within the past ∼130,000 years, and possibly as recent as ∼56,000 years ago, the Sun entered the tenuous tepid partially ionized interstellar material now flowing past the Sun. Prior to that, the Sun was in the low density interior of the Local Bubble. As the Sun entered the local ISM flow,...
By nodal regression and apsidal precession, the Earth flattering at satellite low Earth orbits (LEO) is manifested. Nodal regression refers to the shift of the orbit’s line of nodes over time as Earth revolves around the Sun. Nodal regression is orbit feature utilized for circular orbits to be Sun synchronized. A sun-synchronized orbit lies in a plane that maintains a fixed angle with respect t...
This article presents the development of an image-based sun position sensor and the algorithm for how to aim at the Sun precisely by using image processing. Four-quadrant light sensors and bar-shadow photo sensors were used to detect the Sun's position in the past years. Nevertheless, neither of them can maintain high accuracy under low irradiation conditions. Using the image-based Sun position...
This paper presents a novel tracking based motion segmentation algorithm. The tracking is done by fitting successively more elaborate models of optical flow on the tracked region and the segmentation is done by extracting the regions of the image that are consistent with the computed model of flow. The method can track objects in image sequences with moving background, taken by a hand-held came...
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