Numerical and analytic results for the macroscopic magneto-transport of three-dimensional periodic composites

The strong-field magneto-transport in a generic three-dimensional composite with a periodic microstructure where all the constituents are normal metals is considered. The macroscopic response in such systems turns out to be considerably simpler than it is in the absence of a magnetic field. Closed form asymptotic expressions are found for the microscopic current distributions and macroscopic effective magneto-resistivity tensor components. Numerical calculations of the current distributions and effective magneto-resistivity tensor components are also performed and compared with the closed form asymptotic expressions. A new critical point is identified.     

Nonlinear responses of the periodic structure composed of single negative materials

We investigate the nonlinear responses of the one-dimensional periodic structure containing alternate single negative materials. The transmission property of this nonlinear periodic structure is studied and the bistable behavior is found. Similar as in the linear periodic structure, the transmission property of this nonlinear structure in the zero phase (zero-?) gap region is found to be relatively insensitive to the incident angle from 0° to 30°, in comparison with that in the Bragg gap. Especially, the transmissions associated with the zero-? gap reach the peaks at almost the same input intensity for different incident angles. Another merit of the transmission property in the zero-? gap is that a lower threshold is needed to achieve the bistability than in the Bragg gap. The electric field distribution in the system is further studied. We observe the zero-? gap soliton and compare it with the usual Bragg gap soliton. The differences between these two kinds of solitons are analyzed, and the zero-? gap soliton is shown to be insensitive to the incident angle. In the end, we find that the transmission and the soliton in the zero-? gap are also weakly dependent on the loss and the scaling in contrast to that in the Bragg gap.     

Generalized uncertainty principle and black hole entropy

Recently, there has been much attention devoted to resolving the quantum corrections to the Bekenstein–Hawking black hole entropy. In particular, many researchers have expressed a vested interest in the coefficient of the logarithmic term of the black hole entropy correction term. In this Letter, we calculate the correction value of the black hole entropy by utilizing the generalized uncertainty principle and obtain the correction terms of entropy, temperature and energy caused by the generalized uncertainty principle. We calculate Cardy–Verlinde formula after considering the correction. In our calculation, we only think that the Bekenstein–Hawking area theorem is still valid after considering the generalized uncertainty principle and do not introduce any assumption. In the whole process, the physics idea is clear and calculation is simple. It offers a new way for studying the corrections caused by the generalized uncertainty principle to the black hole thermodynamic quantity of the complicated spacetime.     

Statistical-Mechanical Entropies of Schwarzschild Black Hole due to Arbitrary Spin Fields in Different Coordinates

The statistical-mechanical entropies of the Schwarzschild black hole arising from the scalar, Weyl neutrino, electromagnetic, Rarita-Schwinger and gravitational fields are investigated in the Painlevg and Lemaitre coordinates. Although the metrics in the Painlevg and the Lemaitre coordinates do not obviously possess the singularity as that in the Schwarzschild coordinate, we find that the entropies of the arbitrary spin fields in both the Painlevd and Lemaitre coordinates are exactly equivalent to that in the Schwarzschild coordinate.     

Electromagnetic Parameters Model and Microwave Absorption for Composite Coatings Containing Magnetic Particles

Considering the eddy current effect of the magnetic metal particles in a high frequency electromagnetic field, we extend the Maxwell-Garnett law by introducing the eddy-effect parameter A which is as functions of the radius, permeability and electric conductivity of the metal particle medium. It is obvious that the computational result agrees with the experiment, which indicates that the extended Maxwell-Garnett law can be used to predict the effective electromagnetic parameters of a dilute metal-insulator composite medium in a high-frequency electromagnetic field.     

Chemical reactivity of PVD-coated WC-Co tools with steel

The chemical reactivity of CrN, ZrN, TiC_xN_1−x and naCo^® PVD coatings on a WC-Co cemented carbide substrate with steel has been evaluated by means of the static interaction couples technique. Diffusion experiments with coated and uncoated tools were carried out at 900, 1100 and 1300 °C in order to establish the maximum temperature at which the substrate-coating-workpiece combinations are chemically stable. Computational equilibrium thermodynamics was used to identify the interaction products formed at elevated temperature and the chemical solubility of the different coating materials into iron. A metallic (Fe, Co) fcc solid solution was identified at the steel side of the interface from 1100 °C on for all the coated tools and from 900 °C for the uncoated carbide. In addition to this interaction product, the ?-carbide was identified at 1300 °C on the WC-Co side of the interface. Both of the experimental findings and thermodynamic equilibrium solubility calculations demonstrated that the PVD-coated WC-Co tools exhibit a lower chemical reactivity with respect to the uncoated tools.     

Charged Particle Tunnels from the Slowly Varying Reissner-Nordstroem Black Hole

Extending Parikh and Wilczek＇s work to the non-stationary black hole, we discuss the Hawking radiation of the slowly varying Reissner-NordstrSm black hole by considering the unfixed background spacetime and the selfgravitation interaction. The result shows that the tunnelling rate is related to both the variation of BekensteinHawking entropy and the radiation spectrum deviating from the purely thermal one. This is in agreement with Parikh and Wilczek＇s result. Then a new method to study Hawking radiation of the non-stationary black holes is presented.     

Dipolar-glass-like behaviour of 0.7PMN-0.3PZ ceramic

Relaxor ferroelectric behaviour has been observed for lead magnesium niobate-lead zirconate (0.7PMN-0.3PZ) ceramic. The freezing temperature obtained from fitting of dielectric data to the Vogel-Fulcher equation is very close to the dielectric-maximum temperature and to the temperature of collapse of remanant polarization. The temperature dependence of the spontaneous polarization follows a modified Neel's equation. Specific-heat measurement shows canonical glass-like behaviour, and the value of the glass-transition temperature is very close to the freezing temperature obtained from the Vogel-Fulcher equation. All the observations together indicate that 0.7PMN-0.3PZ ceramic behaves like a dipolar glass.     

Properties of Sr- and Sb-doped PZT–Portland cement composites

Lead zirconate titanate (PZT) ceramic-cement-based composites have increasingly been recognized as an attractive new composite material for use as a sensor in structural applications. In this work, PZT was doped with Sr and Sb (PSZT) to give it greater dielectric constant (ε _r) and higher piezoelectric coefficient (d ₃₃) values than normal PZT and is the first time that it is mixed with normal Portland cement to produce a 0–3 connectivity PSZT–Portland cement composite using PSZT contents of 50% and 70% by volume. Scanning electron micrographs show PSZT ceramic particles closely surrounded by the hydrated cement matrix where a dense microstructure can be observed in the interfacial zone. Both the ε _r and d ₃₃ values were found to increase with PSZT content and the values are amongst the highest so far for these types of composites, where the ε _r and d ₃₃ values reached 590 and 48 pC/N, respectively.     

Free energy landscape from path-sampling: application to the structural transition in LJ38

We introduce a path-sampling scheme that allows equilibrium state-ensemble averages to be computed by means of a biased distribution of non-equilibrium paths. This non-equilibrium method is applied to the case of the 38-atom Lennard-Jones atomic cluster, which has a double-funnel energy landscape. We calculate the free energy profile along the Q₄ bond orientational order parameter. At high or moderate temperature the results obtained using the non-equilibrium approach are consistent with those obtained using conventional equilibrium methods, including parallel tempering and Wang-Landau Monte Carlo simulations. At lower temperatures, the non-equilibrium approach becomes more efficient in exploring the relevant inherent structures. In particular, the free energy agrees with the predictions of the harmonic superposition approximation.