Papers by Keyword: Disconnection

Abstract: The Schmid law says that yielding takes place when resolved shear stress on slip plane reaches the critical value. It is valid for wide variety of materials. However, it is well known that breaking of Schmid law takes place in bcc materials due to non-planar splitting of dislocation cores. The non-Schmid behavior is also possible for plastic deformation of fcc and hcp materials. Particularly, it is sometimes reported for deformation twinning. Present paper demonstrates the non-Schmid phenomena in hcp magnesium by means of computer simulations. We consider influence of non-glide stress components on motion of screw <a> dislocation as well as migration of twin boundaries.

Abstract: Disconnection is the real one which influences the transmission of data and media in the wireless environment. Due to the influence on the transmission quality, the disconnections are divided into temporary disconnections and longtime disconnections. To solve the disconnections, Wireless TCP Disconnection Management was propounded, which concludes TCP Fast Reconnection Mechanism for the Temporary Disconnection and User-Defined Times of TFRMTD. First, TFRMTD mechanism in the wireless was discussed in detail, which implements the fast reconnection through giving every client a unique ID and catching the results at the server. Second, UDTT is introduced, which discusses how to judge the failing of TFRMTD on the disconnections and then conclude its a longtime disconnection.

Abstract: The structure of disconnections in symmetrical low- and high-angle [0001] tilt boundaries in an hcp metal are studied using atomic-scale simulation. Applied engineering strains cause such defects to move conservatively along the boundaries, producing coupled shear and migration. The Peierls stresses causing such motion are found to decrease precipitously through the transition from low- to high-angle boundaries. The reason underlying this behaviour is discussed.

Abstract: In the power system, out-of-step disconnection is the final defensive line of protection, requiring high reliability. This paper analyzed the physical meaning of out-of-step and the principles of disconnection to study the applicability of each discrimination method. It analyzed characteristics and variations of some parameters while oscillation or out-of-step, including impedance, frequency, cosine voltage, etc. It created relevant fuzzy functions and fuzzy rules with trapezoidal membership function based on the given characteristics and variations. Then a comprehensive out-of-step algorithm is achieved by integrating fuzzy functions together with given fuzzy rules. The output is defuzzied to be the final result with barycenter method to make decisions. This algorithm is tested to be more generic.

Abstract: Magnetic shape-memory alloys owe their exceptional properties primarily to the accompanying effects of a martensitic phase transformation. The twinning disconnection as elementary carrier of magnetic-field-induced deformation is the starting point of the present study. A disconnection is a line defect similar to a dislocation but located at an interface and exhibiting a step character besides a dislocation character. The mutual interaction of disconnections is fully tractable by the theory of dislocations. Due to the martensitic transformation, a hierarchical twin microstructure evolves, details of which are controlled through disconnection-disconnection interaction. Depending on the mutual orientation of twin boundaries on different hierarchical levels, twinning disconnections are incorporated in higher hierarchical twin boundaries forming disclination walls, or they stand off individually from those interfaces. Disconnections which stand off from interfaces contribute to magnetoelasticity, i.e. recoverable magnetic-field-induced deformation. Disconnections in disclination walls contribute to magnetoplasticity, i.e. permanent magnetic-field-induced deformation, if the twin thickness is large. In self-accommodated martensite with very thin twins, resulting from a martensitic transformation without training, the deformation is fully magnetoelastic and small. In single-domain crystals, resulting from effective thermo-magnetomechanical training, the deformation is fully magnetoplastic and large. Between these limiting cases, there is a continuous spectrum where, as a rule, the fraction of magnetoplastic strain and the total strain increase with increasing effectiveness of training.