Modern Physics Letters B

The published work on analytical ("mathematical") and computer-aided, primarily finite-element-analysis (FEA) based, predictive modeling of the dynamic response of electronic systems to shocks and vibrations is reviewed. While understanding the physics of and the ability to predict the response of an electronic structure to dynamic loading has been always of significant importance in military, avionic, aeronautic, automotive and maritime electronics, during the last decade this problem has become especially important also in commercial, and, particularly, in portable electronics in connection with accelerated testing of various surface mount technology (SMT) systems on the board level. The emphasis of the review is on the nonlinear shock-excited vibrations of flexible printed circuit boards (PCBs) experiencing shock loading applied to their support contours during drop tests. At the end of the review we provide, as a suitable and useful illustration, the exact solution to a highly nonlinear problem of the dynamic response of a "flexible-and-heavy" PCB to an impact load applied to its support contour during drop testing.

An effective-substrate method was presented to obtain the optical constants of an iron native oxide layer with unknown optical constants and film thickness on an iron substrate with unknown optical constants by using spectroscopic ellipsometry (SE). "Thick" iron films were deposited on silicon wafer by magnetron sputtering and were exposed to air at room temperature. They were measured by spectroscopic ellipsometry during this procedure at different time points from ten minutes to seven months. Pseudo optical constants were calculated from the initially measured data and were introduced into the modeling work of subsequent measurements as an effective substrate in order to obtain the optical constants and film thickness of the native oxide layer. After obtaining the optical constants of the subsequent native oxide layer, they were employed in the modeling work of the initially measured data and the optical constants of the iron substrate and the film thickness of the initial native oxide layer was obtained.

In this paper, we consider propagation of a monochromatic laser beam in an array of semiconductor carbon nanotubes. Initial distribution of the beam intensity is taken in the form of a Gaussian profile in the plane perpendicular to the wave vector. The electromagnetic field in an array of nanotubes is described by Maxwell equations, reduced to a multidimensional wave equation. With an approximation of the slowly varying amplitudes and phases, we derive the effective equation describing the time-averaged field intensity distribution of the laser beam in a medium. Numerical solution of the derived equations allows us to analyze the dependence of the diffractive spreading of the beam on its frequency and initial amplitude. Furthermore, the influence of the nanotube radius on the diffractive spreading of the laser beam is investigated.

Using the coherent potential approximation, we study zero-temperature Mott transition in the half-filled Hubbard model on the honeycomb lattice. Although a pseudogap is already present for the non-interacting case, the gap will not occur until the onsite Coulomb repulsion exceeds a critical value U ≈ 3.6t, where t is the hopping integral. When increasing U/t, the density of states at the Fermi energy first goes up gradually from zero and after reaching a maximum it goes down to zero again. Our calculated critical interaction U_C/t is in very good agreement with the ones obtained by quantum Monte Carlo simulation and cluster dynamical mean-field theory.

In this paper, we perform hybrid Langevin and molecular dynamics simulations on a two-dimensional, united-atom, mesoscopic model to obtain the phase diagram for a solid undergoing a magneto-structural transition. The interatomic exchange interactions are inspired by ab initio calculations in the Ni₂MnGa system. The spins are updated with the help of Langevin soft spin dynamics. The nature of the phase diagram obtained from our simulations is similar to that obtained experimentally in Ni_2+xMn_1-xGa Heusler alloys showing magnetic and martensitic transitions with excess Ni stoichiometry viz. x.

Recent microscopic calculations for the vacancy formation in α-Zr show that both the vacancy formation enthalpy and entropy increase differently upon increasing the temperature. An explanation of this difference is forwarded by making use of the physical significance of the Anderson–Gruneisen parameter.

In this paper, we obtain the pairwise quantum discord for a three-qubit W-class state, and investigate the monogamy property of quantum discord by two different ways (relative entropy-based distance and geometric square-norm distance). Through numerical calculations, we find that a party cannot have maximal quantum correlations with the other two parties simultaneously. For the given state, the quantum correlation between particles 1 and 3 induces limitation on the quantum correlation between them and particle 2. Moreover, the result also shows that the geometric quantum discord of the given W-class state obeys the monogamy property while the entropy quantum discord violates.