Identification of the temperature field and stresses in a thermosensitive cylinder according to the surface strains

We identify the time dependence of temperature of a surface of a long hollow thermosensitive cylinder and its thermal and thermal stressed states according to the known temperature and strains on the other surface. The posed problem is reduced to the inverse problem of thermoelasticity. By using the solution of the direct problem of thermoelasticity, we perform the numerical verification of the proposed procedure of solution of the inverse problem. __________ Translated from Fizyko-Khimichna Mekhanika Materialiv, Vol. 43, No. 6, pp. 55–61, November–December, 2007.     

Contaminant transmission through contactless seals of machine-tool spindles

Russian Engineering Research -     

Quasistatic temperature stresses in a multilayer thermally sensitive cylinder

An approach to the evaluation of nonstationary temperature fields and the thermoelastic state of multilayer hollow long thermally sensitive cylinders based on the use of the Kirchhoff substitution, generalized functions, and Greens functions of the corresponding problems for a hollow cylinder with piecewise constant physicomechanical characteristics is illustrated. The problem of heat conduction is reduced to the solution of a Fredholm-Volterra nonlinear integral equation of the second kind for the Kirchhoff variable. In the problem of thermoelasticity, the coefficients of the equation (continuous inside each layer) are approximated by piecewise constant functions. The boundary conditions at the ends of the cylinder are satisfied in the integral form. Numerical analysis is performed for the case of a three-layer cylinder.Translated from Fizyko-Khimichna Mekhanika Materialiv, Vol. 40, No. 4, pp. 7–16, July–August, 2004.     

Time-Resolved and Spatio-Temporal Analysis of Complex Cognitive Processes and their Role in Disorders like Developmental Dyscalculia

The aim of this article is to report on the importance and challenges of a time-resolved and spatio-temporal analysis of fMRI data from complex cognitive processes and associated disorders using a study on developmental dyscalculia (DD). Participants underwent fMRI while judging the incorrectness of multiplication results, and the data were analyzed using a sequence of methods, each of which progressively provided more a detailed picture of the spatio-temporal aspect of this disease. Healthy subjects and subjects with DD performed alike behaviorally though they exhibited parietal disparities using traditional voxel-based group analyses. Further and more detailed differences, however, surfaced with a time-resolved examination of the neural responses during the experiment. While performing inter-group comparisons, a third group of subjects with dyslexia (DL) but with no arithmetic difficulties was included to test the specificity of the analysis and strengthen the statistical base with overall fifty-eight subjects. Surprisingly, the analysis showed a functional dissimilarity during an initial reading phase for the group of dyslexic but otherwise normal subjects, with respect to controls, even though only numerical digits and no alphabetic characters were presented. Thus our results suggest that time-resolved multi-variate analysis of complex experimental paradigms has the ability to yield powerful new clinical insights about abnormal brain function. Similarly, a detailed compilation of aberrations in the functional cascade may have much greater potential to delineate the core processing problems in mental disorders.     

Simulation of Circuit of Autodyne Sensor with Field-Controlled Transistor

The autodyne sensor operation modelling was carried out. Authors took into account frequency dependence of the field transistor parameters. The shape and a spectrum of generated oscillations in control points of the autodyne sensor circuit were researched, depending on position of an operating point of the transistor. It is revealed, that a condition of the least distortion of the generated oscillations shape is position of a working point of the transistor in the region of camber of its transfer characteristic. Modelling was carried out with Micro-Cap application     

Green function for a layer with rigidly fixed bases

The Green function for a layer with rigidly fixed bases is constructed by using the two-dimensional Fourier integral transformation. The singular part is presented in the closed form. The terms taking into account the influence of the boundaries of the layer are presented in the form of improper integrals of exponentially decreasing functions. The numerical analysis is performed for one component of the Green matrix under the action of a concentrated force at a point of the layer noncentral across the thickness. __________ Translated from Fizyko-Khimichna Mekhanika Materialiv, Vol. 44, No. 4, pp. 39–42, July–August, 2008.     

Methods for the determination of static and dynamic stresses in bodies with subsurface cracks

We study the analytic and numerical methods for the solution of problems of the theory of cracks located near the surfaces of three-dimensional and thin-walled bodies under thermal and force static and dynamic loads. We describe the influence of the surfaces of the body or the interfaces between its materials on the static and dynamic stress intensity factors in the vicinity of the defects.