Multi-Legged Robot Control Using GA-Based Q-Learning Method With Neighboring Crossover

摘要

Superconductivity is a very curious phenomenon characterized by a phase transition at a critical temperature (T c ) in which the conducting phase is in equilibrium with the superconducting phase. The most important properties of the superconducting phase are: zero resistance, ideal diamagnetism (Meissner effect), magnetic flux quantization and persistent current in superconducting rings, cylinders or coils. On the other hand, many effects are found in superconducting constrictions as well as in junctions between two superconductors or in junctions between a superconductor and a conductor. These effects are known as "Josephson effects": (1) It is possible to occur tunneling of Cooper pairs across a thin insulator between two superconductors and thus a superconducting current may be maintained across the junction; (2) when we apply an electric field gradient across a Josephson junction an electromagnetic wave may be produced, (3) when a beam of electromagnetic waves is incident over a Josephson junction a variable electric potential difference may be produced. Due to all the effects mentioned above, superconducting devices may be projected for an enormous number of practical applications. Superconducting wires can be used for power transmission and in other applications when zero resistance is required. A possible application of magnetic levitation is the production of frictionless bearings that could be used to project electric generators and motors. Persistent currents can be used in superconducting magnets and in SMES (superconducting magnetic energy storage). Devices based on the Josephson effects are actually been used in very sensitive magnetometers and appropriate devices based on these effects may give rise to a new generation of faster computers. Superconducting magnets are been used in particle accelerators and may also be used to levitate trains. Many of these devices are successfully been used and new devices are been developed. However, the actual use of these superconducting devices is limited by the fact that they must be cooled to low temperatures to become superconducting. Currently, the highest T c is approximately equal to 135 K at 1 atm The discovery of a room temperature superconductor should trigger a great technological revolution. A book with a discussion about room temperature superconductivity is available The knowledge of the microscopic mechanisms of oxide superconductors should be a theoretical guide in the researches to synthesize a room temperature superconductor. However, up to the present time, the microscopic mechanisms of high-T c superconductivity are unclear. In the present chapter we study microscopic mechanisms in high-T c superconductors.