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BULGARIAN ACADEMY OF SCIENCES NATIONAL COMMITTEE OF THEORETICAL AND APPLIED MECHANICS Journal of Theoretical and Applied Mechanics
Print ISSN: 0861-6663 Online ISSN: 1314-8710
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JTAM, Sofia, vol. 43 Issue 2 (2013) |
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FOREWORD TO THE SPECIAL ISSUE devoted to 70th Anniversary of Prof. Stefan Radev, Corresponding Member of the Bulgarian Academy of Sciences Nikolay K. Vitanov Chairman of the Scientific session devoted to the 70th Anniversary of Prof. Stefan Radev
On 20th of November 2012 a scientific session on the occasion of the 70th Anniversary of prof. Stefan Radev has been held at the Institute of Mechanics of the Bulgarian Academy of Science. In this issue selected and reviewed contributions from this session are presented.
JTAM, Sofia, vol. 43 Issue 2 pp. 003-003 (2013)
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CITATION OF FIVE TECHNICAL PAPERS PUBLISHED IN JOURNAL OF THEORETICAL AND APPLIED MECHANICS, Vol. 42, No. 1 AND 2 PUBLISHED WITH THE FINANCIAL SUPPORT OF PROJECT BG051PO001–3.3.05.–0001 “SCIENCE AND BUSINESSâ€, FUNDED ON OPERATIONAL PROGRAM “DEVELOPMENT OF HUMAN RESOURCES†AT THE “EUROPEAN SOCIAL FUNDâ€
The cited below five technical papers are published in Journal of Theoretical and Applied Mechanics,Vol. 42, No. 1 and 2 with the financial support of project BG051PO001–3.3.05.–0001 “Science and businessâ€, funded on Operational program “Development of human resources†at the “European social fundâ€:
JTAM, Sofia, vol. 43 Issue 2 pp. 004-004 (2013)
The five technical papers cited below are published in the following sites: http://versitaopen.com/jtam http://versita.com/jtam http://www.degruyter.com/view/j/jtam http://www.imbm.bas.bg/tm/jtam/index.html [1] Kazakoff, Al. B. Advances in Engineering Software for Lift Transporta- tion Systems. Journal of Theoretical and Applied Mechanics, 42 (2012), No. 1, 3–22. [2] Rizov, V. I. Fracture in Composites – An Overview (Part I). Journal of Theoretical and Applied Mechanics, 42 (2012), No. 2, 3–42. [3] Parvanova, S. Calculation of Stress Intensity Factors Based on Force-displacement Curve Using Element Free Galerkin Method. Journal of Theoretical and Applied Mechanics, 42 (2012), No. 1, 23–40. [4] Mladensky, A. S., V. I. Rizov. Application of J-Integral in the Case of a Single Crack in Cantelever Beam. Journal of Theoretical and Applied Mechanics, 42 (2012), No. 1, 41–54. [5] Stoilov, G., V. Kavardzhikov, D. Pashkouleva. A Comparative Study of Random Patterns for Digital Image Corelation. Journal of Theo- retical and Applied Mechanics, 42 (2012), No. 2, 55–66. |
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Review on the Instability and Optics of Capillary Jets and Glass Fibres: A Fruitful Collaboration between Institute of Mechanics and IUSTI St. Radev1, F. R. A. Onofri2, A. Lenoble2, L. Tadrist2 1Institute of Mechanics, Bulgarian Academy of Sciences, Acad. G. Bonchev St., Bl. 4, 1113 Sofia, Bulgaria 2IUSTI UMR 7343 CNRS/Aix-Marseille University, 5 r. E. Fermi, Technopˆole de Chˆateau Gombert, Marseille 13453, France
The paper review key results [1-14] of the joint researches conducted by IMech and IUSTI. In the First part, we review models and experimental results on the linear and nonlinear instability of a capillary jet including both axisymmetric and nonaxisymmetric disturbances. In the Second part, results on draw resonances, occurring during a glass fibre process are reviewed, as well as the unique optical models and methods developed to perform these studies.
JTAM, Sofia, vol. 43 Issue 2 pp. 005-30 (2013), [Full Article]
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Integrability of Differential Equations with Fluid Mechanics Application: From Painleve Property to the Method of Simplest Equation Zlatinka I. Dimitrova1, Kaloyan N. Vitanov2 1“G. Nadjakov†Institute of Solid State Physics, Bulgarian Academy of Sciences, 71, Tzarigradsko Chaussee Blvd, 1784 Sofia, Bulgaria 2Faculty of Mathematics and Informatics, “St. Kliment Ohridski†University of Sofia, 5, J. Bourchier Blvd, 1164 Sofia, Bulgaria
We present a brief overview of integrability of nonlinear ordinary and partial differential equations with a focus on the Painleve property: an ODE of second order possesses the Painleve property if the only movable singularities connected to this equation are single poles.
The importance of this property can be seen from the Ablowitz-Ramani- Segur conhecture that states that a non-linear PDE is solvable by inverse scattering transformation only if each nonlinear ODE obtained by ex- act reduction of this PDE possesses the Painleve property. The Painleve property motivated much research on obtaining exact solutions on non-linear PDEs and leaded in particular to the method of simplest equation. A version of this method called modified method of simplest equation is discussed below.
JTAM, Sofia, vol. 43 Issue 2 pp. 031-42 (2013), [Full Article]
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Deep-Water Waves: On the Nonlinear Schrödinger Equation and Its Solutions Nikolay K. Vitanov1, Amin Chabchoub2, Norbert Hoffmann2 1Institute of Mechanics, Bulgarian Academy of Sciences, Acad. G. Bonchev St., Bl. 4, 1113 Sofia, Bulgaria 2Institute of Mechanics and Ocean Engineering, Hamburg University of Technology, 21073 Hamburg, Germany
We present a brief discussion on the nonlinear Schrödinger equation for modelling the propagation of the deep-water wavetrains and a discussion on its doubly-localized breather solutions, that can be connected to the sudden formation of extreme waves, also known as rogue waves or freak waves.
JTAM, Sofia, vol. 43 Issue 2 pp. 043-54 (2013), [Full Article]
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Rayleigh Wave in a Rotating Initially Stressed Piezoelectric Half-Space Baljeet Singh1, Ranbir Singh2 1Department of Mathematics, Post Graduate Government College, Sector 11, Chandigarh-160 011, India 2Department of Mathematics, Modern Institute of Engineering and Technology, Ambala, Haryana, India
The governing equations of an initially stressed rotating piezoelectric medium are solved for surface wave solutions. The appropriate solutions in the half-space of the medium satisfy the required boundary conditions to obtain the frequency equation of Rayleigh wave for
charge free as well as electrically shorted cases. The non-dimensional speed of the Rayleigh wave is computed numerically for particular examples of Lithium niobate and PZT-5H ceramics. The effects of rotation and initial stress are observed graphically on the non-dimensional speed of the Rayleigh wave.
JTAM, Sofia, vol. 43 Issue 2 pp. 055-68 (2013), [Full Article]
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On Nonlinear Waves in the Spatio-Temporal Dynamics of Interacting Populations Ivan Jordanov, Elena Nikolova Institute of Mechanics, Bulgarian Academy of Sciences, Acad. G. Bonchev St., Bl. 4, 1113 Soï¬a, Bulgaria
In this paper the spatial-temporal dynamics of the members of interacting populations is described by means of nonlinear partial differential equations. We consider the migration as a diffusion process influenced by the changing values of the birth rates and the coefficients of interaction between the populations. The general model is reduced to analytically tractable partial differential equations (PDE) with polynomial nonlinearity up to third order for the particular case of one population and one spatial dimension. We obtain an analytical solution which describes nonlinear kink and solitary waves in the population dynamics by applying the modiï¬ed method of simplest equation to the described model.
JTAM, Sofia, vol. 43 Issue 2 pp. 069-76 (2013), [Full Article]
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Optimization of the Code of the Numerical Magnetosheath-Magnetosphere Model P. Dobreva Institute of Mechanics, Bulgarian Academy of Sciences, Acad. G. Bonchev St., Bl. 4, 1113 Soï¬a, Bulgaria
The proposed three dimensional model contains two earlier developed 3D regional numerical models: a grid-characteristic model of the magnetosheath and a ï¬nite element model of the magnetosphere. The model output is the distribution of gas-dynamic parameters in the magnetosheath and of magnetic ï¬eld inside the magnetosphere. The efforts are focused on the modernization of the existing software, written in Fortran, using several techniques for parallel programming such as OpenMP extensions. After analyzing the numerical performance of the model a possible scenario for the code optimization is shown. First results with the improved variant of the model are presented.
JTAM, Sofia, vol. 43 Issue 2 pp. 077-82 (2013), [Full Article]
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Simulation of Fluid Flow in Centrifugal Tricanter Cristian Puscasu1, Mihaela Grigorescu1, Axene Ghita1, Raluca Voicu1, Mariana Stefanescu1, Victoria Teleaba2, Ivanka Zheleva 1National Research & Development Institute for Gas Turbines COMOTI, I220D, Iuliu Maniu Avenue, sector 6, Code 061126, OP76, CP 174, Bucharest, Romania 2Ruse University “Angel Kanichevâ€, 8, Studentska Street, 7017, Russe, Bulgaria
An ANSYS simulation of the multiphase complex fluid flow motion in a centrifugal device (tricanter) is presented in the paper. This centrifugal device is designed for one step efficient solution for contaminated river water processing with oil and oil products. The proposed tricanter is one of the main objectives of the project named “Common strategy to prevent the Danube’s pollution technological risks with oil and oil products CLEANDANUBE†financed by European Commission within the frame of Romania-Bulgaria Trans-Border Cooperation Program 2007 – 2013 (grant MIS-ETC code 653). Results for liquid phases (water and oil products) and for solid particles motion are presented graphically and are commented.
JTAM, Sofia, vol. 43 Issue 2 pp. 083-94 (2013), [Full Article]
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Evolution Equation for Nonlinear Long-Wavelength Monotonic Marangoni Instability in a Binary Liquid Layer with Nonlinear Soret Effect S. Slavtchev1, P. Kalitzova-Kurteva1, A. Oron2 1Institute of Mechanics, Bulgarian Academy of Sciences, Acad. G. Bonchev St., Bl. 4, 1113 Sofia, Bulgaria 2Department of Mechanical Engineering, Technion-Israel Institute of Technology, Haifa 32000, Israel
The Soret effect in binary systems is called nonlinear when the thermo-diffusive flux is proportional to the temperature gradient with a coefficient being linear function of the concentration of one of the solute components. This effect is significant in highly dilute solutions. The long- wavelength Marangoni instability in a thin layer of binary liquid, in the presence of the nonlinear Soret effect, is considered. The nonlinear dynamic behaviour of the liquid system is studied in the case of monotonic instability. The solution of the dimensionless equations of mass and momentum balances, heat transfer and mass diffusion is searched near the linear instability threshold, in the form of series in a small parameter that measures the supercriticality. An equation for spatiotemporal evolution of the liquid system is derived based on the first two approximations.
JTAM, Sofia, vol. 43 Issue 2 pp. 095-102 (2013), [Full Article]
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Prof. Stefan Radev, Corresponding Member of the Bulgarian Academy of Sciences and His Contributions to Fluid Mechanics Sonia Tabakova |
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