Features of the refractometry of turbulent gas flows

The features of the interference refractometry of turbulent gas flows, which are a special case of a randomly inhomogeneous medium, are considered. Recommendations are made on the quasi-optimal choice of the parameters of the refractometer system. Translated from Izmeritel’naya Tekhnika, No. 8, pp. 31–35, August, 1996.     

Phase Equilibria in the System HfO2–Y2O3–CaO

Phase equilibria in the system HfO₂–Y₂O₃–CaO were studied in the temperature range 1250° to 2850°C by both experimental methods (X-ray phase analysis at 20° to 2000°C, petrography, annealing and quenching, differential thermal analysis in He at temperatures to 2500°C, thermal analysis in air using a solar furnace at temperatures to 3000°C, and electron microprobe X-ray analysis) and theoretical means (development of a mathematical model for the liquidus surface by means of the reduced polynomial method). Phase equilibria were determined by the structure of the restricting binary systems. No ternary compounds were found. The liquidus was characterized by the presence of six four-phase, invariant equilibria. Solid solutions were based on monoclinic (M), tetragonal (T), and cubic (F) modifications of HfO₂; C and H forms of Y₂O₃; CaO; and CaHfO₃ that crystallized in two polymorphous modifications, namely, the cubic and rhombic perovskite-type structure.     

Active adaptation in robotic assembly

A two-point contact model in robotic assembly is considered, in a quasi-static formulation. In the experiments, a robot equipped with a force and torque sensor is employed. The consistency of theoretical analysis with physical experiments is discussed.     

EFFECTIVE DIFFUSION COEFFICIENT OF ACTIVE SOLVENTS IN COMPOSITE POLYMERIC MATERIALS

ABSTRACT

A method and a device for determination of the effective diffusion coefficient of active solvents in composite polymeric materials (CPM) based on cellulose derivatives are proposed and examined. This method accounts for anomalous mass transfer phenomena, considerable shrinkage and changes of sorption capacity of the CPM specimen allowing selection of the rational technological regime. Results of experimental studies on diffusion of acetone and ethanol in cellulose nitrate with various degrees of substitution are given as examples.     

A method for the amplitude–phase synthesis of antenna array based on control of the set of nonidentical partial beams

An iterative method for the amplitude–phase synthesis of antenna arrays based on control of the set of partial beams is proposed. In this method, two additional partial beams are added to the radiation pattern at each step. The shape of each beam is optimized with consideration for the difference between the synthesized and specified radiation patterns. Parameters specifying the shape of additional partial beams are chosen with the help of the genetic algorithm. The results of numerical studies allowing comparison of the proposed synthesis method to the least-squares method and the method based on control of the set of identical partial beams are presented.