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Quantum Dynamics of Tribosystems
Published in Dmitry N. Lyubimov, Kirill N. Dolgopolov, L.S. Pinchuk, Quantum Effects in Tribology, 2017
Dmitry N. Lyubimov, Kirill N. Dolgopolov, L.S. Pinchuk
Jeans, based on Newtonian gravitation theory and the equations of hydrodynamics, studied small density perturbations, the flow velocities and the gravitational potential in a homogeneous medium. He defined them as the waves determined by a value called Jeans wavelength Xj. The Xj quantity characterizes the minimum perturbation scale, starting from which the matter elastic forces are unable to resist the gravitational forces. As a result, the gravitational instability begins followed by uncontrolled sphere contraction and finally leading to the singularity surrounded by the event horizon and having space-time distortions. Under Jeans theory, the wavelength Xj is calculated by the formula: λJ=csπGρ $$ \lambda _{J} = c_{s} \sqrt {\frac{\pi }{{G\rho }}} $$
Introduction to heat transfer
Published in Tariq Muneer, Jorge Kubie, Thomas Grassie, Heat Transfer, 2012
Tariq Muneer, Jorge Kubie, Thomas Grassie
Based on the principles of quantum mechanics Hawking argued that pairs of particles – pairs of photons and gravitons – continually appear at the event horizon of a black hole. For the purpose of this text, and without indulging into the details of astronomical science, we may loosely consider the event horizon to be the radius at which the escape velocity is the speed of light. Two particles in a pair that start out together may then move apart. After an interval of time they come together and annihilate one another. Some of the pairs will be pairs of matter particles, one of the pair being an antiparticle. Hawking argued that particle pairs appear at the event horizon. However, before the pair meet again and annihilate each other, the one with the negative energy crosses the event horizon into the black hole. The particle with positive energy, now freed of its partnership, may now escape. To an observer at a distance it appears to come out of the black hole and this is known as Hawking radiation.
Miscellaneous Algorithms
Published in Nazmul Siddique, Hojjat Adeli, Nature-Inspired Computing, 2017
The gravity of black hole is very strong because matter has been condensed into a small space. A black hole has a boundary. The sphere-shaped boundary of a black hole in space is known as the event horizon. It is where the gravity is just so strong that drags light back and prevents it escaping and nothing can get away from it. Anything that crosses the boundary of the black hole will be swallowed by it and vanish. The radius of the event horizon is termed as the Schwarzschild radius. At this radius, the escape speed is equal to the speed of light, and once light passes through, even it cannot escape. Nothing can escape from within the event horizon because nothing can go faster than light. The Schwarzschild radius R is calculated by the following equation (Schwarzschild, 1916): R≡2⋅G⋅Mc2 where G is the gravitational constant, M is the mass of the black hole, and c is the speed of light. If anything moves close to the event horizon or crosses the Schwarzschild radius, then it will be absorbed into the black hole and will disappear forever. The curiosity of general people in black holes revived once again in the 1980s when Stephen Hawking published his book A Brief History of Time: From the Big Bang to Black Holes (Hawking, 1998). The black holes are large objects in the universe, the construction of which is based on the concept of space-time (Chadrasekhar, 1998). The recent studies on the black hole in the 1970s and 1980s are presented in Davies (1978) and Hawking (1976, 1992, 1993). The very recent observations on black holes are reported in Abbott et al. (2016).
Improved black hole and multiverse algorithms for discrete sizing optimization of planar structures
Published in Engineering Optimization, 2019
Saeed Gholizadeh, Navid Razavi, Emad Shojaei
One of the newly developed metaheuristics is the BH algorithm (Hatamlou 2013). A black hole is a region of space with a huge amount of concentrated mass. Nothing falling into a black hole can escape from its gravitational pull and thus anything that enters a black hole is lost from the universe. The boundary of a black hole is known as the event horizon and if an object crosses its radius, the black hole absorbs it. The BH algorithm tries to simulate the above-mentioned phenomenon. The BH is a population-based algorithm and its basic steps are described below: