Preferential Engagement and What Can We Learn from Online Chess?

Minds and Machines - An online game of chess against a human opponent appears to be indistinguishable from a game against a machine: both happen on the screen. Yet, people prefer to play chess...     

Thin-Film Nanotechnology for Power Sources

Russian Engineering Research - Thin-film vacuum technology permits the creation of new electrode materials on the basis of a flexible carbon matrix with a highly developed surface. Supercapacitor...     

Efficient mixed Timoshenko–Mindlin shell elements

The precise representation of rigid body motions in the displacement patterns of curved Timoshenko–Mindlin (TM) shell elements is considered. This consideration requires the development of the strain–displacement relationships of the TM shell theory with regard to their consistency with the rigid body motions. For this purpose a refined TM theory of multilayered anisotropic shells is elaborated. The effects of transverse shear deformation and bending‐extension coupling are included. The fundamental unknowns consist of five displacements and eight strains of the face surfaces of the shell, and eight stress resultants. On the basis of this theory the simple and efficient mixed models are developed. The elemental arrays are derived using the Hu–Washizu mixed variational principle. Numerical results are presented to demonstrate the high accuracy and effectiveness of the developed 4‐node shell elements and to compare their performance with other finite elements reported in the literature. Copyright © 2002 John Wiley & Sons, Ltd.     

The influence of titanium oxide nanocoatings on the surface quality of glass products for electronic devices

The formation of a defect-free continuous titanium oxide coating on the surface of borosilicate glass in the course of synthesis by the molecular layering method is revealed using atomic-force microscopy. This coating ensures a significant decrease in the roughness of the initial surface.     

A kinetic model for the combustion of carbon in a porous medium

A model is proposed for infiltration combustion, which incorporates the reaction kinetics more fully. Calculations have been performed on a multicomponent system with complicated kinetics, which show that the kinetic parameters have a marked effect on the basic working ones. It has been shown by varying the water-air ratio for wet combustion that the completeness of the conversion of the fuel increases with the initial water concentration, and that the speed of the combustion front and the combustion temperature increase.Chernogolovka. Translated from Fizika Goreniya i Vzryva, Vol. 29, No. 3, pp. 136–139, May–June, 1993.     

Structure of chromium-nickel steel 14KH17N2 after high-temperature tempering

The structure of steel 14Kh17N2 after quenching exhibits -phase (ferrite alloyed with chromium and nickel), which causes the formation of streaks, filaments, and other defects in the metal during rolling and hot pressure treatment. The properties of the microstructure of this steel can be judged by the state of the carbide phase segregating on phase interfaces and inside grains. A complex analysis of the changes in the state of the carbide phase M₂₃C₆ in the process of high-temperature tempering of steel 14Kh17N2 (for example, at 700°C is of practical interest. The results of this analysis make it possible to make recommendations on improvement of the properties of the steel and to refine the optimum chemical and phase compositions.Translated from Metallovedenie i Termicheskaya Obrabotka Metallov, No. 5 , pp. 36–38, May, 1995.     

Refined model for the current-voltage characteristics of quantum-well infrared photodetectors

The temperature dependences of the dark current of quantum-well infrared photodetectors are investigated experimentally. It is established that the pre-exponential factor in the analytical expression for the photodetector current-voltage characteristics varies linearly with temperature. On the basis of the results obtained, it is suggested that the temperature dependence of the photodetector??s dark current is determined by the thermal excitation of charge carriers to a band characterized by a two-dimensional density of states. In the context of this suggestion, a refined model for the current-voltage characteristics is proposed. The model takes into account the thermal generation of charge carriers in a band with a two-dimensional density of states and the electric field dependence of the thermal activation energy for the quantum-well ground state and of the drift velocity of the carriers in the barrier conduction band.     

Analysis of quality-of-service metrics in IMS networks

A network constructed according to the IMS architecture consists of different modules that sequentially process signaling messages transferred during providing communication services. Delays that occur when processing signaling messages determine the quality of service for subscribers. International recommendations define the quality-of-service metrics, which include not only the mean, but also the 95% quantile. The paper proposes an approach to analyzing the quality-of-service characteristics. It is assumed that IMS-network nodes work as multi-server queues with general service time distribution.     

Local bifurcations in the periodic boundary value problem for the generalized Kuramoto–Sivashinsky equation

For a version of the generalized Kuramoto–Sivashinsky equation with “violated” symmetry, the periodic boundary value problem was investigated. For the given dynamic distributed-parameter system, consideration was given to the issue of local bifurcations at replacing stability by spatially homogeneous equilibrium states. In particular, the bifurcation of the two-dimensional local attractor with all Lyapunov-unstable solutions on it was detected. Analysis of the bifurcation problem relies on the method of the integral manifolds and normal forms for the systems with infinitely dimensional space of the initial conditions.