Phase Diagrams of Polytype Transformations in Close-Packed Crystals Including Metastable States

The paper offers a method for calculating phase diagrams of polytype transformations in close-packed crystals based on the generalized axial Ising's model of finite dimensions at non-zero temperatures. Using the Metropolis algorithm, the behavior of systems with polytype transitions is studied under the conditions of changing external shear stress and temperature. The longest polytype period considered here is taken to be 30 close-packed planes.     

Integral Equation Method in Electromagnetic-Sounding Inverse Problems

The use of the integral equation method in electromagnetic-sounding inverse problems is considered. Several approaches to the solution of these inverse problems are proposed.     

Approaches to sharing knowledge in group problem structuring

Problem-structuring techniques are an integral aspect of ‘Soft-OR’. SSM, SAST, Strategic Choice, and JOURNEY Making, all depend for their success on a group developing a shared view of a problem through some form of explicit modelling. The negotiated problem structure becomes the basis for problem resolution. Implicit to this process is an assumption that members of the group share and build their knowledge about the problem domain. This paper explores the extent to which this assumption is reasonable. The research is based on detailed records from the use of JOURNEY Making, where it has used special purpose Group Support software to aid the group problem structuring. This software continuously tracks the contributions of each member of the group and thus the extent to which they appear to be ‘connecting’ and augmenting their own knowledge with that of other members of the group. Software records of problem resolution in real organisational settings are used to explore the sharing of knowledge among senior managers. These explorations suggest a typology of knowledge sharing. The implications of this typology for problem structuring and an agenda for future research are considered.     

On wave radiation induced by a fast shock wave in an oblique magnetic field

The corrugation stability of the flat surface of a fast magnetohydrodynamic shock wave in a perfect monoatomic gas with a constant heat capacity is studied with numerical techniques. The magnetic field makes an arbitrary angle with the plane of discontinuity. It is shown that the shock wave remains stable only if it is strictly perpendicular to the magnetic field. At any other angle between the fast shock wave and magnetic field, the former may spontaneously radiate outwardly propagating magnetohydrodynamic waves under certain conditions. Incoming flow characteristics at which these waves are induced are determined.     

Investigation and modelling of damping in a plate with a bonded porous layer

Behavior of a poro-elastic material bonded onto a vibrating plate is investigated in the low-frequency range. From the analysis of dissipation mechanisms, a model accounting for damping added by the porous layer on the plate is derived. This analysis is based on a 3-D finite element formulation including poro-elastic elements based on Biot displacement theory. First, dissipated powers related to thermal, viscous and viscoelastic dissipation are explicited. Then a generic configuration (simply-supported aluminium plate with a bonded porous layer and mechanical excitation) is studied. Thermal dissipation is found negligible. Viscous dissipation can be optimized as a function of airflow resistivity. It can be the major phenomenon within soft materials, but for most foams viscoelastic dissipation is dominant. Consequently an equivalent plate model is proposed. It includes shear in the porous layer and only viscoelasticity of the skeleton. Excellent agreement is found with the full numerical model.     

InAs/GaAs (1 1 1)A heteroepitaxial systems

We studied the structural, electrical, and mechanical properties of an InAs thin film grown on GaAs (1 1 1)A substrates by molecular beam epitaxy. In contrast to conventionally used (0 0 1) surfaces, where Stranski–Krastanov growth dominates the highly mismatched heteroepitaxy, layer-by-layer growth of InAs can be established. One of the largest advantages of this unique heteroepitaxial system is that it provides a two-dimensional electron gas system in the near-surface region without the problem of electron depletion. We review the fundamental properties and applications of this unique heteroepitaxial system.     

Two scenarios for phase-transformation in disordered media

The reasons for the existence of various scenarios for structural transformations in disordered condensed media, such as liquids and amorphous substances, where both smeared transformations and sharp first-order transitions may occur, were analyzed. The ratio between the spatial scale of structural correlations and the size of the smallest possible region occupied by a new phase in the matrix of initial modification is the key parameter determining the scenario for equilibrium phase transformations in liquids. In amorphous substances, the experimentally observed transformations occur far from equilibrium, and the possible size of the region occupied by the new phase corresponds to the minimal nucleus size. For some amorphous solids, quantitative analysis of the transformation width was carried out and the main classes of covalent substances, in which the smeared or sharp transitions occur, were revealed. Specific features of the interparticle interactions determining various transformation scenarios are discussed.     

玻璃的冲击损伤

冲蚀过程是一个与颗粒反复冲击物体表面而移除物质相关的表面现象．本文研究了玻璃的冲蚀坑的几何尺寸和体积，给出了冲蚀移除物质如何依赖于颗粒流动速度、颗粒尺寸和冲击角的理论关系．通过理论与实验结果相比较，定义了一定冲蚀坑尺度的有效域．     

On the Bavrin Integro-Differential Operators and Their Applications to Solution of Functional Equations

We construct a multiplicative group structure in the class of integro-differential operators specific for a polydisk which was introduced by I. I. Bavrin. We indicate two applications of these operators to solution of functional equations.     

Experimental evidence for anisotropic response of a driven vortex lattice

We present kinetic inductance measurements in current driven Josephson junction arrays. Measurements performed with circular coils indicate that this technique is very sensitive to the vortex mobility. Results obtained with anisotropic detection coils provide experimental evidence for the anisotropic response of a driven vortex lattice. Anisotropic behavior is obtained when rising the temperature or the mean vortex velocity as indicated by the loss of the superconducting shielding capability, first in the direction of vortex motion and then in the perpendicular direction.