Portable Microwave Reflection Coefficient Meter of Coatings

Journal of Communications Technology and Electronics - In this study, we propose a new design of a portable meter of reflection coefficients of radar absorbing coatings. An experimental comparison...     

Structural and Textural States of Steel 06G2MB Strips After Controlled Thermomechanical Treatment

Metal Science and Heat Treatment - Orientation microscopy (EBSD) is used to study structural and textural states through the thickness of pipe steel strips after a controlled thermomechanical...     

Aluminum (Iron) Phosphate Glasses Containing Rare Earth and Transuranium Elements: Phase Composition,Oxidation State of Np and Pu,and Hydrolytic Durability

Samples of aluminum (iron) phosphate glasses containing weighable amounts of rare earth and transuranium elements were synthesized. The quenched glasses obtained are X-ray amorphous, and in the course of annealing they undergo partial crystallization with segregation of a poorly soluble phase of monazite structure. However, the hydrolytic durability of the glasses remains on the level meeting the requirements to immobilized high-level waste (no more than 10^–7 g cm^–2 day^–1). Plutonium in the surface layer of the glass samples occurs in oxidation state IV, and neptunium, mainly in oxidation states IV and V.     

Finding Forces Required to Change Air Hammer Path in Soil

The authors solve the problem on forces required to change drilling path of air hammers in soil. Soil mass is assumed a rigid–plastic medium with the Mohr–Coulomb yield, and the air hammer deviator is considered as a nondeformable body. The problem is solved in two stages: introduction of the deviator in soil and travel of the air hammer in soil with the rear deviated at a certain angle. The loads applied to the rear, the forces and the moment required to changing the path of an air hammer in soil are calculated.     

Influence of the microprojection geometry on the elastic contact of surfaces with regular microrelief

The influence of surface microprojections—their shape and additional harmonics—on the elastic contact of a flat surface and a surface with regular microrelief is considered on the basis of the elastic contact of a half-plane and an undulatory surface. It is shown that the contact-pressure curve depends on the surface gradient of the microprojection and the mutual influence of adjacent microprojections.     

The role of electron-electron interaction in the process of charge-carrier capture in deep quantum wells

The role of electron-electron interaction in the process of electron capture to a deep quantum well is investigated. Using two-level and three-level quantum wells as examples, the basic electron-capture mechanisms, i.e., the interaction with optical phonons and the Coulomb electron-electron interaction, are considered, and the corresponding capture probabilities and electron lifetimes are calculated. The effect of Auger recombination on the charge-carrier distribution in a quantum well is also taken into account. With this taken into consideration, a set of rate equations is solved for a nonsteady-state mode, and the time dependences of the electron concentration at the ground energy level in the quantum well are found. The contributions of each of the recombination processes under consideration are shown.     

Distribution of luminescence centers in the bulk of undoped,Fe-doped,and Cr-doped CVD ZnSe polycrystals studied by two-photon confocal microscopy

Edge and defective-impurity luminescence in polycrystalline CVD ZnSe has been studied in the range 0.46–0.73 μm by two-photon confocal microscopy. We have obtained luminescence intensity distribution maps for undoped, iron-doped, and chromium-doped ZnSe samples at depths of up to 1 mm with a spatial resolution of a few microns. It has been shown that crystal regions with low dopant concentrations contain centers that luminesce in the ranges 520–580 and >670 nm. The parts of the crystals with high iron and chromium concentrations contain centers that suppress the edge and defective-impurity (520–580 nm) luminescence. We discuss the nature of these centers and demonstrate the possibility of assessing the luminescence characteristics of grain boundaries in CVD ZnSe.