Modern Physics Letters B

Boltzmann–Arrhenius–Zhurkov (BAZ) model enables one to obtain a simple, easy-to-use and physically meaningful formula for the evaluation of the probability of failure (PoF) of a material after the given time in operation at the given temperature and under the given stress (not necessarily mechanical). It is shown that the material degradation (aging, damage accumulation, flaw propagation, etc.) can be viewed, when BAZ model is considered, as a Markovian process, and that the BAZ model can be obtained as the steady-state solution to the Fokker–Planck equation in the theory of Markovian processes. It is shown also that the BAZ model addresses the worst and a reasonably conservative situation, when the highest PoF is expected. It is suggested therefore that the transient period preceding the condition addressed by the steady-state BAZ model need not be accounted for in engineering evaluations. However, when there is an interest in understanding the physics of the transient degradation process, the obtained solution to the Fokker–Planck equation can be used for this purpose.

We report here a microscopic theory of the temperature dependence of specific heat in high-T_c cuprate superconductors. The system is described by a model Hamiltonian consisting the antiferromagnetic spin fluctuations due to the impurity f-electrons as well as the conduction electrons, besides the superconducting interaction due to the itinerant electrons. The Hamiltonian is treated within a mean-field approach. The transverse spin fluctuation parameters and the superconducting gap are calculated by Zubarev's Green's function technique and solved self-consistently. The temperature dependent specific heat is calculated from the free energy in order to study the anomalies appearing at the spin fluctuation and superconducting transition temperatures. The evolutions of these anomalies are studied by varying the model parameters of the systems and results are discussed in reference to experimental observations.

With the application of the dynamic control system, Cellular Automata model has become a valued tool for the simulation of human behavior and traffic flow. As an integrated kind of railway signal-control pattern, the four-aspect color light automatic block signaling has accounted for 50% in the signal-control system in China. Thus, it is extremely important to calculate correctly its carrying capacity under the automatic block signaling. Based on this fact the paper proposes a new kind of "cellular automata model" for the four-aspect color light automatic block signaling under different speed states. It also presents rational rules for the express trains with higher speed overtaking trains with lower speed in a same or adjacent section and the departing rules in some intermediate stations. In it, the state of mixed-speed trains running in the section composed of many stations is simulated with CA model, and the train-running diagram is acquired accordingly. After analyzing the relevant simulation results, the needed data are achieved herewith for the variation of section carrying capacity, the average train delay, the train speed with the change of mixed proportion, as well as the distance between the adjacent stations.

Ground states are studied by solving a modified Ginzburg–Landau model for mesoscopic metallic superconducting rings. It is found that surface effect related spin-orbit (SO) interaction can generate an effective orbital magnetic field of opposite orientations for spin-up and spin-down electrons which leads to spin-polarized states with opposite chirality. The quantum phase transition between the spin-polarized states and spin singlet superconducting states can occur by applying an external magnetic field normal to the ring-plane.

We report our study on the magnetic properties of Si-doped ZnO thin films fabricated by pulsed laser deposition technique. The Si-doped ZnO thin films show ferromagnetism at room temperature. The saturation magnetism increases from 0 to 2.4 emu/cc with the increasing of Si concentration up to 2%, and then decreases with further increasing of Si concentration. First-principles calculation demonstrates that the origination of ferromagnetism for Si-doped ZnO system is the two unpaired electrons of Si-2p. These unpaired electrons increase the magnetic moments which are responsible for the increasing ferromagnetism.

After a review of the coupled Newton's equations for a small alignment of grains with a fixed reflecting end wall, the equations are put into block diagrams of Simulink. Simulink simulations are given for 6 grain systems for cubic and Hertz intergrain potentials. The expected granular solitary waves are seen in the simulations. The block diagrams hence convert a single impulse into a traveling energy bundle of fixed width. This work forms the necessary first step for the eventual realization of the mathematical system represented by the granular chain as a Very Large Scale Integrated (VLSI) circuit.

The fatigue and fracture behavior of C/C composites fabricated using fine-woven carbon fiber laminates with α = 0/90° direction were investigated. Also, the phenomenon of crack growth behavior and the shear damage in the fiber bundle was discussed. Slits of several sizes were cut on both sides of a test section and different sizes of slit length were chosen. The effect of the slit configuration on crack initiation and growth behavior was observed. Specimens with blunt-notches and center-holes were also used to compare the fatigue strength and crack growth behavior. Non-propagating cracks were observed and fatigue limit was defined as the maximum stress at which specimen did not break for N = 10⁷ cycles stress application. The longest fatigue life was obtained in the case of specimens with shorter slits. The relationships between fatigue strengths and specimen shapes were analyzed by stress concentration, K_t, and stress intensity factor, K_I. The effect of slit configuration on fatigue strength was then discussed regarding both the experimental and calculated consequences.

With the aid of molecular simulations, a new aluminum organic framework structure is designed, and the hydrogen storage capability of the designed structure is studied using grand canonical Monte Carlo technique. Results show that the hydrogen storage capacity of aluminum organic framework at 77 K and 1 MPa is about 430 hydrogen molecules per unit cell, the corresponding weight density be equivalent to 17.45 wt.%. The preferential adsorption site is located at the aluminum–oxygen cluster. Hydrogen molecules are preferentially distributed on the surface of Al ions. The complexation of organic linkers with Al ions is found to be in favor of the adsorption of hydrogen.

The Gross–Pitaevskii equation for polarized molecules is an integro-differential equation, consequently it is complicated for solving. We find a possibility to represent it as a nonintegral nonlinear Schrödinger equation, but this equation should be coupled with two linear equations describing the electric field. These two equations are the Maxwell equations. We recapture the dispersion of collective excitations in the three-dimensional electrically polarized BEC with no evolution of the electric dipole moment directions. We trace the contribution of the electric dipole moment. We explicitly consider the contribution of the electric dipole moment in the interaction constant for the short-range interaction. We show that the spectrum of dipolar BEC does not reveal instability at repulsive short-range interaction. Nonlinear excitations are also considered. We present dependence of the bright soliton characteristics on the electric dipole moment.