Topological defects formation with momentum dissipation

We employ holographic techniques to explore the effects of momentum dissipation on the formation of topological defects during the critical dynamics of a strongly coupled superconductor after a linear quench of temperature. The gravity dual is the dRGT massive gravity in which the conservation of momentum in the boundary field theory is broken by the presence of a bulk graviton mass. From the scaling relations of defects number and “freeze-out” time to the quench rate for various graviton masses, we demonstrate that the momentum dissipation induced by graviton mass has little effect on the scaling laws compared to the Kibble-Zurek mechanism. Inspired from Pippard’s formula in condensed matter, we propose an analytic relation between the coherence length and the graviton mass, which agrees well with the numerical results from the quasi-normal modes analysis. As a result, the coherence length decreases with respect to the graviton mass, which indicates that the momentum dissipation will augment the number of topological defects.

Deflection of a beam with a transverse crack under dead load

This paper proposes an analytic relation for the deflection of a cantilever beam with a transverse crack subjected to dead load. The mathematical relation is deduced involving the decreased capacity of the beam to store energy, which is in direct relation with the crack position and depth. Eventually, the validity of the relation is proved by means of the finite element method.

Value-at-Risk Modeling with Conditional Copulas in Euclidean Space Framework

This paper aims to establish an analytic relation between a time-varying conditional copula and the value at risk modeled by the underlying. Specically, under the asumption that the space is euclidean we use scalar product to clarify a link between the conditional copula varying with time and norms. It is then established a new expression on the geometric yield

Modelling and testing the electromagnetic near field shielding effectiveness achieved by woven fabrics with conductive yarns

The current extensively development of electrical devices and telecommunication requires adequate solutions for ensuring electromagnetic compatibility (EMC). One of the main solutions provided by EMC is the shielding against electromagnetic (EM) radiation. Conventional screens for EM radiation are constructed from metallic plates, however, fabrics with conductive yarns may be used as well, with multiple advantages: lightweight, flexibility, mechanical resistance and 3D shape ability. The paper addresses the shielding of the electromagnetic near field, by proposing an analytic relation taking into account both geometrical and electrical parameters of the fabric, based on the circuit method. A validation study was performed, by measuring the shielding effectiveness of an enclosure with a cover from woven fabrics with conductive yarns. The experimental setup includes both the electrical measurement devices, as well as a set of five woven fabrics with conductive yarns from stainless steel and silver. The experimental results for the electromagnetic near field frequency range (1–20 MHz) present values in good relationship to the analytic relation. The simplified analytic relation allows the computing of the distance between the conductive yarns of the woven fabric in relation to the targeted shielding effectiveness. This relation supports the design process of a fabric, with balance between its costs and its target shielding effectiveness.