Surface barrier diode based on zinc selenide with a passivating zinc oxide film

We propose a method of fabricating surface barrier diodes with overlapped metal junction, which provides for a significant decrease in the reverse currents and an increase in the breakdown voltage.     

Modeling large reversible electric-field-induced strain in ferroelectric materials using 90° orientation switching

Reversible large electric-field-induced strain caused by reversible orientation switchings in BaTiO3 is modeled using the Landau's theory of phase transition. A triple well free energy function is constructed. Each of its minima is associated with one of the polarization orientations involved. Nonlinear constitu- tive laws accounting for reversible orientation switchings and electrostriction effects are obtained by using thermodynamic equilibrium conditions. Hysteretic dynamics of one-dimensional structures is described by coupled nonlinear differential equations. Double hysteretic loops in the electric and me- chanic fields are both successfully modeled. Giant reversible electrostriction is modeled as a conse-quence of reversible orientation switchings via electro-mechanical couplings. Comparisons with ex-perimental results reported in literatures are presented.     

Mixed group ranks: preference and confidence in classifier combination

Classifier combination holds the potential of improving performance by combining the results of multiple classifiers. For domains with very large numbers of classes, such as biometrics, we present an axiomatic framework of desirable mathematical properties for combination functions of rank-based classifiers. This framework represents a continuum of combination rules, including the Borda Count, Logistic Regression, and Highest Rank combination methods as extreme cases. Intuitively, this framework captures how the two complementary concepts of general preference for specific classifiers and the confidence it has in any specific result (as indicated by ranks) can be balanced while maintaining consistent rank interpretation. Mixed Group Ranks (MGR) is a new combination function that balances preference and confidence by generalizing these other functions. We demonstrate that MGR is an effective combination approach by performing multiple experiments on data sets with large numbers of classes and classifiers from the FERET face recognition study.     

Modeling of nonideal volume Bragg reflection gratings in photosensitive glass using a perturbed transmission matrix approach

Reflection spectra of volume Bragg gratings written in bulk photosensitive silicate glass for wavelength division multiplexing applications are modeled using a transmission matrix approach. This allows for the examination of the effects of spatial perturbations along the grating due to chirp, apodization, compositional inhomogeneities, and index contrast saturation leading to reflection spectra that are asymmetric about the Bragg peak. Effects of the nonlinear relationship between index contrast in the glass and exposure flux on the reflection spectrum is also studied. Volume Bragg gratings are fabricated in UV exposure-sensitive silicate glasses containing alkali-halide nano-crystalline domains, and their reflection spectra are compared with calculation. The magnitude and uniformity of the index changes observed in our glass gratings make them useful in a wide range of wavelength multiplexing applications.     

Isogeometric analysis of a dynamic thermo-mechanical phase-field model applied to shape memory alloys

This paper focuses on the numerical simulation of martensitic transformations in shape memory alloys (SMAs) using a phase-field model. We developed a dynamic thermo-mechanical model for SMAs, using strain based order parameter, having a bi-directional coupling between structural and thermal physics via strain, strain rate and temperature. The model involves fourth order spatial derivatives representing a domain wall. We propose an isogeometric analysis numerical formulation for straightforward solution to the fourth order differential equations. We present microstructure evolution under different loading conditions and dynamic loading simulations of the evolved microstructures of SMAs of different geometries to illustrate the flexibility, accuracy and stability of our numerical method. The simulation results are in agreement with the numerical and experimental results from the literature.     

Spectrum of bulk and surface spin oscillations in “strip” films

Experimental and theoretical investigations of the magnetic resonance of “strip” films were conducted. In magnetic fields below the saturation field, when “strip” films possess a periodic domain structure, a multimode character of the absorption spectrum was discovered. The spectrum of spin oscillation taking into account exchange and magnetic dipole interaction was computed. Comparison of the computed results with the experimental data permits the identification of the observed peaks as bulk and surface modes of a spin wave resonance.     

Intracenter excited state of copper in Cu-compensated InP

In studies of the spectra of the photoconductivity of impurity of the samples of Cu-compensated InP, a resonant transition from one state of copper to another with the maximum of optical energy of excitation of 0.31 eV is found. The temperature dependence of the intensity’s maximum of the intracenter transition in the range from 90 to 450 K is obtained. It is established that the thermal energy of excitation is 0.42 eV.