Vibration of beams and rotating shafts under thermal effects

Temperature variations can significantly change the dynamic characteristics of structures. In the presented paper we have studied the clamped isotropic rotor under thermal effects. We have studied aluminium and copper beam. Because the expansion is restrained by the clamping, the beam undergoes internal stresses, which induce changes in dynamic characteristics. We have also expanded and developed Marques and Inman model as well as Bahzad and Bastami model. We have taken into account the compound influence of thermal force, axial force in rotating shaft and gyroscopic effect. The behavior of rotating shaft is studied in the temperature range of 250-700 K. The influence of temperature-dependent material properties was considered primarily with respect to temperature variations. The presented research work demonstrates a very good agreement between experimental data and results from our vibrational model. On the basis of the proposed analytical model it is possible to determine the vibrational characteristics in very wide range of temperatures. The reported paper is the first one in scientific literature to consider collectively the combined influence of temperature, gyroscopic effects and rotor speeds on shaft and beam vibration

Bifurcations in annular electroconvection with an imposed shear

We report an experimental study of the primary bifurcation in electrically-driven convection in a freely suspended film. A weakly conducting, submicron thick smectic liquid crystal film was supported by concentric circular electrodes. It electroconvected when a sufficiently large voltage $V$ was applied between its inner and outer edges. The film could sustain rapid flows and yet remain strictly two-dimensional. By rotation of the inner electrode, a circular Couette shear could be independently imposed. The control parameters were a dimensionless number ${\cal R}$, analogous to the Rayleigh number, which is $\propto V^2$ and the Reynolds number ${\cal R}e$ of the azimuthal shear flow. The geometrical and material properties of the film were characterized by the radius ratio $\alpha$, and a Prandtl-like number ${\cal P}$. Using measurements of current-voltage characteristics of a large number of films, we examined the onset of electroconvection over a broad range of $\alpha$, ${\cal P}$ and ${\cal R}e$. We compared this data quantitatively to the results of linear stability theory. This could be done with essentially no adjustable parameters. The current-voltage data above onset were then used to infer the amplitude of electroconvection in the weakly nonlinear regime by fitting them to a steady-state amplitude equation of the Landau form. We show how the primary bifurcation can be tuned between supercritical and subcritical by changing $\alpha$ and ${\cal R}e$.Comment: 17 pages, 12 figures. Submitted to Phys. Rev. E. Minor changes after refereeing. See also http://mobydick.physics.utoronto.c

Китаб Ибрагима Хосеневича из коллекции Национальной библиотеки Республики Беларусь как исторический источник : реферат к дипломной работе / Инна Чеславовна Кевра; БГУ, Исторический факультет, Кафедра источниковедения; науч. рук. Белявский А.М.

The construct of individualism–collectivism (IND-COL) has become the definitive standard in cross-cultural psychology, management, and related fields. It is also among the most controversial, in particular, with regard to the ambiguity of its dimensionality: Some view IND and COL as the opposites of a single continuum, whereas others argue that the two are independent constructs. We explored the issue through seven different tests using original individual-level data from 50 studies and meta-analytic data from 149 empirical publications yielding a total of 295 sample-level observations that were collected using six established instruments for assessing IND and COL as separate constructs. Results indicated that the dimensionality of IND-COL may depend on (a) the specific instrument used to collect the data, (b) the sample characteristics and the cultural region from which the data were collected, and (c) the level of analysis. We also review inconsistencies, deficiencies, and challenges of conceptualizing IND-COL and provide guidelines for developing and selecting instruments for measuring the construct, and for reporting and meta-analyzing results from this line of research

Deep learning: New computational modelling techniques for genomics.

As a data-driven science, genomics largely utilizes machine learning to capture dependencies in data and derive novel biological hypotheses. However, the ability to extract new insights from the exponentially increasing volume of genomics data requires more expressive machine learning models. By effectively leveraging large data sets, deep learning has transformed fields such as computer vision and natural language processing. Now, it is becoming the method of choice for many genomics modelling tasks, including predicting the impact of genetic variation on gene regulatory mechanisms such as DNA accessibility and splicing