عضويتلغو عضويتPowered by WebGozar
فالنامه ی حافظ براي ديدن فال خود ابتدا نيت کنيد سپس بر روي يکي از دايره هاي موجود کليک کنيد تا فال خود را مشاهده کنيد (کاری ازمسعود)
Holography could bring 3D TV without the need for special glasses Researchers at Massachusetts Institute of Technology (MIT) have demonstrated the highest frame rate yet for a dynamic hologram that can recreate evolving 3D scenes. The breakthrough means that holographic television is now tantalizingly close to industry frame rates at a time when 3D cinema is fully back in vogue. A big appeal of holograms over established 3D image projection is that the viewer can see the effect unaided. They do not need to wear special glasses where each lens creates a slightly different image by letting through light polarized in different directions. Instead, holographic displays emit light in such a way that it produces many perspectives that allow the viewer to see the "object" from multiple angles. In November, a group of researchers based at the University of Arizona and Nitto Denko Technical Corporation in California made the headlines when they unveiled the world's first "telepresence" system capable of reproducing a changing 3D scene every 2 seconds. The system worked by surrounding an object with 16 cameras and writing these images into a polymer-based screen, which can project when illuminated with LEDs. Filming deep scenes Now, a group at MIT's Media Lab under the leadership of Michael Bove Jr has raised the bar once again by creating a system that can reproduce a 3D scene 15 times every second. And the MIT system uses a novel design that only requires one camera – a commercially available range-finding camera that can record both the luminance and depth of a scene. Bove's team takes this footage and sends it via the internet to a PC that has been fitted with three graphics processing units. The units have been programmed with an algorithm that can compute the diffraction patterns needed to reproduce the moving 3D images. These patterns are then recreated on a projection screen using arrays of components known as "wafels", which can control the intensity of light emitted in all directions. Bove tells physicsworld.com that, having only started developing the latest version of the technique during the week after Christmas, the research has progressed at breakneck speed. "It was literally only last Wednesday that we managed to improve the performance from 7 frames per second to 15." He says that he is confident that his team can boost this rate even higher to the 24 frames per second of feature films or the 30 frames per second of television. Webcam hologram Bove believes that, within the next few years, his group's method of creating dynamic holograms could become available commercially at the scale of standard laptop screens. It could be used by scientists and other professionals to visualize data in 3D, as well as for communications and videogaming. "There's something very compelling for me about the idea of having a hologram coming out of a computer, with images coming via webcam, for instance," he says. The group is looking to develop alternative versions of the diffraction screen at lower costs, and is seeking to design a laptop-scale screen that retails at around $200 (approximately £125). More difficult, however, will be scaling up the devices to the size of cinema screens, because it is difficult to generate complicated diffraction patterns on larger scales
Holography could bring 3D TV without the need for special glasses
Researchers at Massachusetts Institute of Technology (MIT) have demonstrated the highest frame rate yet for a dynamic hologram that can recreate evolving 3D scenes. The breakthrough means that holographic television is now tantalizingly close to industry frame rates at a time when 3D cinema is fully back in vogue.
A big appeal of holograms over established 3D image projection is that the viewer can see the effect unaided. They do not need to wear special glasses where each lens creates a slightly different image by letting through light polarized in different directions. Instead, holographic displays emit light in such a way that it produces many perspectives that allow the viewer to see the "object" from multiple angles.
In November, a group of researchers based at the University of Arizona and Nitto Denko Technical Corporation in California made the headlines when they unveiled the world's first "telepresence" system capable of reproducing a changing 3D scene every 2 seconds. The system worked by surrounding an object with 16 cameras and writing these images into a polymer-based screen, which can project when illuminated with LEDs.
Now, a group at MIT's Media Lab under the leadership of Michael Bove Jr has raised the bar once again by creating a system that can reproduce a 3D scene 15 times every second. And the MIT system uses a novel design that only requires one camera – a commercially available range-finding camera that can record both the luminance and depth of a scene.
Bove's team takes this footage and sends it via the internet to a PC that has been fitted with three graphics processing units. The units have been programmed with an algorithm that can compute the diffraction patterns needed to reproduce the moving 3D images. These patterns are then recreated on a projection screen using arrays of components known as "wafels", which can control the intensity of light emitted in all directions.
Bove tells physicsworld.com that, having only started developing the latest version of the technique during the week after Christmas, the research has progressed at breakneck speed. "It was literally only last Wednesday that we managed to improve the performance from 7 frames per second to 15." He says that he is confident that his team can boost this rate even higher to the 24 frames per second of feature films or the 30 frames per second of television.
Bove believes that, within the next few years, his group's method of creating dynamic holograms could become available commercially at the scale of standard laptop screens. It could be used by scientists and other professionals to visualize data in 3D, as well as for communications and videogaming. "There's something very compelling for me about the idea of having a hologram coming out of a computer, with images coming via webcam, for instance," he says.
The group is looking to develop alternative versions of the diffraction screen at lower costs, and is seeking to design a laptop-scale screen that retails at around $200 (approximately £125). More difficult, however, will be scaling up the devices to the size of cinema screens, because it is difficult to generate complicated diffraction patterns on larger scales
Oct 1, 2010
Physicists are designing new types of nuclear reactor that could be cheaper, greener, safer and more secure than existing plants. But as Edwin Cartlidge discusses, these designs must overcome major technical and financial hurdles if they are ever to see the light of day
After a 20-year slump following accidents at Three Mile Island in the US and Chernobyl in the former Soviet Union, the power of the atom is making a comeback. In the past two years alone, China has begun constructing 15 new nuclear power stations, while Russia, South Korea and India are also initiating major expansions in atomic power. Some Western countries look set to join them: at the end of 2009, licence applications for 22 new nuclear plants had been submitted in the US, while the Italian government has said that it will
Issues and events
Universities welcome efforts to scale back federal controls over campus research by foreign nationals.
Last year J. Reece Roth, an emeritus professor of physics at the University of Tennessee, was sentenced to four years in prison for, among other violations of US export laws, disseminating US Air Force–funded plasma technology for the wing surfaces of unmanned aerial vehicles to two graduate students, one Iranian and one Chinese, in his laboratory. Roth is appealing the verdict, but his experience illustrates the consequences academic researchers and their institutions can face by ignoring or being unaware .....
سياهچاله چيست؟
مترجم: معصومه يوسفي در چند جمله كوتاه ميتوان گفت، سياهچاله ناحيه اي از فضاست كه مقدار بسيار زيادي جرم در آن تمركز يافته و هيچ شيئي نمي تواند از ميدان جاذبه آن خارج شود.از آنجا كه بهترين تيوري جاذبه در حال حاضر تيوري نسبيت عام انيشتن است،در مورد سياهچاله و جزيياتش بايد طبق اين تيوري تحقيق و نتيجه گيري كنيم. ابتدا از مفهوم جاذبه و شرايط ساده تر آغاز مي كنيم. فرض كنيد روي سطح يك سياره ايستاده ايد. يك سنگ را به سمت بالا پرتاب مي كنيد. با فرض اينكه آن را خيلي خيلي محكم پرتاب نكرده باشيد براي مدتي به سمت بالا حركت مي كند و نهايتا شتاب جاذبه باعث مي شود به پايين سقوط كند. اما اگر سنگ را به اندازه ي لازم محكم پرتاب كرده باشيد مي توانيد آن را به كل از جاذبه سياره خارج كنيد و سنگ بالا رفتن را تا ابد ادامه خواهد داد. سرعتي كه لازم است تا يك شيي را از حاذبه سياره خارج كند سرعت فرار يا سرعت گريز نام دارد......
ـ اگر تمام رگ های موجود در بدن انسان را روی یک بگذارند،طول آن به ۹۷هزار کیلومتر میرسد.
ـ شتر در سه دقیقه توانایی خوردن ۹۵لیتر آب را دارد.
ـ وقتی یک مگس روی یک میله فولادی می نشیند،آن میله به اندازه دو میلیونوم میلی متر خم می شود.
ـ شتر مرغ ها تنها موجوداتی هستند که مغزشان کوچک تر از چشمشان است.
ـ حلزون تنها موجود زنده ایست که می تواند سه سال تمام بدون وقفه بخوابد.
