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"VirtuSphere is a spherical virtual reality device. It consists of a 10-foot hollow sphere, which is placed on a special platform that allows the sphere to rotate freely in any direction according to the user’s steps. It works with computer based simulations and virtual worlds, and rotates as the user walks, allowing for an unlimited plane upon which the user can walk. A wireless head- mounted display with gyroscopes is used to both track the user's head movement as well as display the environment of the virtual world. VirtuSphere can serve many purposes, including exercise, video gaming, military training, and virtual museum tours. The VirtuSphere is a creation of Ray and Nurulla Latypov, whose company, VirtuSphere Inc, is based in Binghamton, New York. Using the VirtuSphere simulator Applications Markets and applications for Virtusphere include: *Military, law enforcement, and other dangerous occupations that require a safe training environment *Gaming and entertainment *Health and fitness *Museums and other educational installations *Virtual tours of architectural and construction projects Lockheed Martin has used the VirtuSphere as an input device in a manned simulator at the Mounted Warfare TestBed (MWTB) at Fort Knox, KY. This simulator incorporates the sphere into a single-soldier simulator that is compatible with the Distributed Interactive Simulation and High level architecture protocols. The simulator is composed of the sphere, a pair of infrared mice to track the sphere’s movements, Intersense trackers on the user’s head and weapon, an image generator on a laptop, display goggles for the user, and a simulator host computer, all on a wireless network. Using this simulator, the user can interact with other simulated entities, whether provided by separate manned simulators like the Advanced Concepts Research Tool (ACRT), or by computer-generated forces systems like OneSAF. The simulator is used at the MWTB for experiments that examine future weapon systems and tactics and for evaluating soldiers. See also * Virtual reality * Omnidirectional treadmill References External links * Official Site * Cybersphere, a similar device developed by the University of Warwick and virtual reality company VR Systems UK. * 7 min. video and interview with creators of VirtuSphere and transcript. Virtual reality "
"Channelling is the process that constrains the path of a charged particle in a crystalline solid. Many physical phenomena can occur when a charged particle is incident upon a solid target, e.g., elastic scattering, inelastic energy- loss processes, secondary-electron emission, electromagnetic radiation, nuclear reactions, etc. All of these processes have cross sections which depend on the impact parameters involved in collisions with individual target atoms. When the target material is homogeneous and isotropic, the impact- parameter distribution is independent of the orientation of the momentum of the particle and interaction processes are also orientation-independent. When the target material is monocrystalline, the yields of physical processes are very strongly dependent on the orientation of the momentum of the particle relative to the crystalline axes or planes. Or in other words, the stopping power of the particle is much lower in certain directions than others. This effect is commonly called the "channelling" effect. It is related to other orientation-dependent effects, such as particle diffraction. These relationships will be discussed in detail later. Fig. 1. An about 12 nm thick silicon crystal viewed down the 110 crystal direction Fig. 2. Same Si crystal as in Fig. 1 viewed from a randomly rotated direction. History The channelling effect was first discovered in binary collision approximation computer simulations in 1963 to explain exponential tails in experimentally observed ion range distributions that did not conform to standard theories of ion penetration. The simulated prediction was confirmed experimentally the following year by measurements of ion penetration depths in single-crystalline tungsten. Mechanism From a simple, classical standpoint, one may qualitatively understand the channelling effect as follows: If the direction of a charged particle incident upon the surface of a monocrystal lies close to a major crystal direction (Fig. 1), the particle with high probability will only do small-angle scattering as it passes through the several layers of atoms in the crystal and hence remain in the same crystal 'channel'. If it is not in a major crystal direction or plane ("random direction", Fig. 2), it is much more likely to undergo large-angle scattering and hence its final mean penetration depth is likely to be shorter. If the direction of the particle's momentum is close to the crystalline plane, but it is not close to major crystalline axes, this phenomenon is called "planar channelling". Channelling usually leads to deeper penetration of the ions in the material, an effect that has been observed experimentally and in computer simulations, see Figures 3-5. Negatively charged particles like antiprotons and electrons are attracted towards the positively charged nuclei of the plane, and after passing the center of the plane, they will be attracted again, so negatively charged particles tend to follow the direction of one crystalline plane. Fig. 3. Map of channeling crystal directions for 10 keV Si ions in Si. The red and yellow colors indicate directions with deeper mean ion penetration depth, i.e. directions where the ions are channeled. Fig. 4. Experimentally determined penetration depth profiles for 15 keV B ions in Si along the 100 and 110 crystal channels, as well as in a non-channeling direction. The data is scanned in with smoothing from. Ref. Fig. 5. Computer simulations of the mean penetration depth of 80 keV Xe ion penetration in single crystal Au, considering a tilting of the implantation profile off the main direction. These simulations were made with the MDRANGE code for a study of Xe irradiation of Au nanowires. Also shown are simulations using the binary collision approximation SRIM code which does not take into account the crystal structure and thus does not describe channeling at all. The order of the strength of channeling, i.e. that 110 has the strongest effect, 100 is intermediate and 111 has the weakest, agrees with experimental observations in face-centered cubic metals. Because the crystalline plane has a high density of atomic electrons and nuclei, the channeled particles eventually suffer a high angle Rutherford scattering or energy-losses in collision with electrons and leave the channel. This is called the "dechannelling" process. Positively charged particles like protons and positrons are instead repelled from the nuclei of the plane, and after entering the space between two neighboring planes, they will be repelled from the second plane. So positively charged particles tend to follow the direction between two neighboring crystalline planes, but at the largest possible distance from each of them. Therefore, the positively charged particles have a smaller probability of interacting with the nuclei and electrons of the planes (smaller "dechannelling" effect) and travel longer distances. The same phenomena occur when the direction of momentum of the charged particles lies close to a major crystalline, high- symmetry axis. This phenomenon is called "axial channelling". At low energies the channelling effects in crystals are not present because small-angle scattering at low energies requires large impact parameters, which become bigger than interplanar distances. The particle's diffraction is dominating here. At high energies the quantum effects and diffraction are less effective and the channelling effect is present. Applications There are several particularly interesting applications of the channelling effects. Channelling effects can be used as tools to investigate the properties of the crystal lattice and of its perturbations (like doping) in the bulk region that is not accessible to X-rays. The channeling method may even be utilized to detect the geometrical location of interstitials. This is an important variation of the Rutherford backscattering ion beam analysis technique, commonly called Rutherford backscattering/channeling (RBS-C). At higher energies (tens of GeV), the applications include the channelling radiation for enhanced production of high energy gamma rays, and the use of bent crystals for extraction of particles from the halo of the circulating beam in a particle accelerator. General literature * J.W. Mayer and E. Rimini, Ion Beam Handbook for Material Analysis, (1977) Academic Press, New York * L.C. Feldman, J.W. Mayer and S.T.Picraux, Material Analysis by Ion Channelling, (1982) Academic Press, New York * R. Hovden, H. L. Xin, D. A. Muller, Phys. Rev. B 86, 195415 (2012) * G. R. Anstis, D. Q. Cai, and D. J. H. Cockayne, Ultramicroscopy 94, 309 (2003). * D. Van Dyck and J. H. Chen, Solid State Communications 109, 501 (1999). * S. Hillyard and J. Silcox, Ultramicroscopy 58, 6 (1995). * S. J. Pennycook and D. E. Jesson, Physical Review Letters 64, 938 (1990). * M. V. Berry and Ozoriode.Am, Journal of Physics a-Mathematical and General 6, 1451 (1973). * M. V. Berry, Journal of Physics Part C Solid State Physics 4, 697 (1971). * A. Howie, Philosophical Magazine 14, 223 (1966). * P. B. Hirsch, A. Howie, R. B. Nicholson, D. W. Pashley, and M. Whelan, Electron microscopy of thin crystals (Butterworths London, 1965). * J. U. Andersen, Notes on Channeling, http://phys.au.dk/en/publications/lecture- notes/ (2014) See also * Emission channeling * Electron channeling pattern References External links * CERN NA43 Experiment that investigated interactions of high energy particles with crystals * Note and reports on crystal extraction * The future looks bright for particle channelling on CERN Courier Particle physics "
"Abandoned beehive coke ovens near the ghost town of Cochran, Arizona American 17th century beehive oven front Ephraim Hawley House beehive oven ceiling Ephraim Hawley House beehive oven back, next to water pump A beehive oven is a type of oven in use since the Middle Ages in Europe. It gets its name from its domed shape, which resembles that of a skep, an old-fashioned type of beehive. Its apex of popularity occurred in the Americas and Europe all the way until the Industrial Revolution, which saw the advent of gas and electric ovens. Beehive ovens were common in households used for baking pies, cakes and meat. These ovens were also used in industry, in such applications as making tiles and pots and turning coal into coke. Construction A fire brick chamber shaped like a dome is used. It is typically wide and high. The roof has a hole for charging the coal or other kindling from the top. The discharging hole is provided in the circumference of the lower part of the wall. In a coke oven battery, a number of ovens are built in a row with common walls between neighboring ovens. A battery consisted of a great many ovens, sometimes hundreds of ovens, in a row. Some mines also employed parallel batteries. Cooking food With candle wax wrapped in paper, dry kindling (twigs, small sticks, and/or wood chips), and pine cones, a small fire was made toward the front of the oven. As the fire caught, more kindling was added to produce a thick smoke, which coated the oven with black soot. The fire was then pushed back into the middle of the oven with a hoe. More wood would be added until there was a good, hot fire. After all of these steps were taken, the food would be prepared for baking. The beehive oven typically took two to three hours to heat, occasionally even four hours in the winter. Breads were baked first when the beehive oven was hottest, with other baked items such as cinnamon buns, cakes, and pies. As the oven cooled, muffins and "biscuits" could be baked, along with puddings and custards. After a day's baking there was typically sufficient heat to dry apples and other fruits, vegetables, or herbs. Pots of beans were often placed in the back of the oven to cook slowly overnight. Coke manufacture Coal is introduced from the top to produce an even layer of about deep. Air is supplied initially to ignite the coal. Carbonization starts and produces volatile matter, which burns inside the partially closed side door. Carbonization proceeds from top to bottom and is completed in two to three days. Heat is supplied by the burning volatile matter so no by-products are recovered. The exhaust gases are allowed to escape to the atmosphere. The hot coke is quenched with water and discharged, manually through the side door. The walls and roof retain enough heat to initiate carbonization of the next charge. When coal was burned in a coke oven, the impurities of the coal not already driven off as gases accumulated to form slag, which was effectively a conglomeration of the removed impurities. Since it was not the desired coke product, slag was initially nothing more than an unwanted by-product and was discarded. Later, however, it was found to have many beneficial uses and has since been used as an ingredient in brick-making, mixed cement, granule-covered shingles, and even as a fertilizer. History In the thirteen colonies that later became the United States, most households had a beehive oven. Bread was usually baked in it once a week, often in conjunction with pies, crackers, or other baked goods. To heat the oven, the baker would heap coals and kindling inside and wait several hours. Requiring strict regulation, the right amount of wood to ash had to be burned and then tested by sticking one's hands inside. Then one had to add more wood or open the door to let it cool to the right temperature. Beehive ovens were also used in iron-making. Before this time, iron-making utilized large quantities of charcoal, produced by burning wood. As forests dwindled dangerously, the substitution of coke for charcoal became common in Great Britain, and the coke was manufactured by burning coal in heaps on the ground in such a way that only the outer layer burned, leaving the interior of the pile in a carbonized state. In the late 19th century, brick beehive ovens were developed, which allowed more control over the burning process. The number of beehive ovens between 1870 and 1905 skyrocketed from about 200 to almost 31,000, which produced nearly 18 million tons of coke in the Pittsburgh area alone. One observer boasted that, loaded into a train, "the year's production would make up a train so long that the engine in front of it would go to San Francisco and come back to Connellsville before the caboose had gotten started out of the Connellsville yards!" The number of beehive ovens in the Pittsburgh seam peaked in 1910 at almost 48,000. Although they made a top- quality fuel, beehive ovens poisoned the surrounding landscape. After 1900, the serious environmental damage of beehive coking attracted national notice, even though the damage had plagued the district for decades. "The smoke and gas from some ovens destroy all vegetation around the small mining communities," noted W. J. Lauck of the U.S. Immigration Commission in 1911. Passing through the region on train, University of Wisconsin president Charles van Hise saw "long rows of beehive ovens from which flame is bursting and dense clouds of smoke issuing, making the sky dark. By night the scene is rendered indescribably vivid by these numerous burning pits. The beehive ovens make the entire region of coke manufacture one of dulled sky, cheerless and unhealthful". In China, beehive ovens were not banned until 1996, and this ban was not fully effective until 2011.https://arstechnica.com/science/2018/02/chinese-ban-on-small-coal- burning-ovens-took-15-years/ References External links The Manufacture of Coke in a Beehive Coke Oven * The History of Beehive Ovens in West Blocton, Alabama * Hearthcook.com Steelmaking Ovens Fireplaces "