A weak topological insulator in dimension $3$ is known to have a topologically protected gapless mode along the screw dislocation. In this paper we formulate and prove fact with language of C*-algebra K-theory. The proof based on coarse index theory helical surface.

Extended microscale crystal defects, including dislocations and stacking faults, can radically alter the properties of technologically important materials. Determining the atomic structure and the influence of defects on properties remains a major experimental and computational challenge. Using a newly developed simulation technique, the structure of the 1/2a <100> screw dislocation in nanoporo...

Abstract This work presents a regularized eigenstrain formulation around the slip plane of dislocations and resultant non-singular solutions for various dislocation configurations. Moreover, we derive generalized Eshelby stress tensor configurational force theory in context proposed model. Based on finite element formulation, calculate driving configurations, including single edge/screw disloca...

In this Letter, we propose a model that demonstrates the effect of a free surface on the lattice resistance experienced by a moving dislocation in nanodimensional systems. This effect manifests in an enhanced velocity of dislocation due to the proximity of the dislocation line to the surface. To verify this finding, molecular dynamics simulations for an edge dislocation in bcc molybdenum are pe...

The origin and the formation mechanism of a surface morphological defect in 4H-SiC epilayers are reported. appears on an epilayer as inclined line-like feature at angle ±80° to step-flow direction [ 11 2 ¯ 0 ] . is confirmed originate from threading screw dislocation intersecting its orientation controlled by sign Burgers vector dislocation. forms through interaction local spiral growth associa...

The geometric optimization of orthopedic screws can considerably increase their orthopedic efficiency. Due to the high geometric parameters of orthopedic screws, a finite element simulation is an effective tool for analyzing and forecasting the effect of the parameters on the load-bearing capacity of different types of screws and bones. Thus, in the present study, the tensile strength of a typi...

The compressive creep deforrn;~tiort microstructure of polycrystalline Ni3AI h:is been observed by transnlission electron microscopy (TEM). ( 1 1 I ) rind ( 110) slip systems have been identified in primary creep. Dissociatiort of edge superparti:~l pairs perpendicular to the slip plane (both { 11 1 ) and ( 110) ) is common in crept specimens. I'he formation of this superdislocation...

Many of the papers studying the screw-drive system dynamic model concentrated on the control methodologies that is why vibrational models are either simple lumped models or simplified flexible beam models. In this paper a screw-drive system dynamic model and its vibrations are discussed. The screw is considered as an EulerBernoulli type flexible beam with fixed-free boundary conditions and the ...

Posterior atlantoaxial dislocation without odontoid fracture is extremely rare and often results in fatal spinal cord injury. According to the reported literature, all cases presented mild or no neurologic deficit, with no definite relation to upper spinal cord injury. Little is reported about traumatic posterior atlantoaxial dislocation, with incomplete quadriplegia associated with a spinal co...

background: pelvic ring injuries and sacroiliac dislocations have significant impacts on patient’s quality of life. several techniques have been described for posterior pelvic fixation. the current study has been designed to evaluate the spinopelvic method of fixation for sacroiliac fractures and fracture-dislocations.   methods: between january 2006 and december 2014, 14 patients with sacroili...