Anastas Ivanov Ivanov - Academia.edu (original) (raw)
Dear colleagues, dear friends! I like writing the technical books as well as the playing of tennis. Even my colleagues tell me "Professor of tennis". Of course, I am not. But I like this sport and I practice it regularity. So, I reached to investigations in the field of Aerodynamics and mainly the motion of sport balls as tennis balls, golf balls, soccer balls and others. Of course, I remain specialist mainly in the field of Theoretical Mechanics (Rigid Body Mechanics) and Structural Mechanics.
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Address: BULGARIA, 1574 SOFIA, 159 Geo Milev Str.
Todor Kableshkov University of Transport
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This approach based on the matrix formalism for Lie al-gebraic tools provides a constructive meth... more This approach based on the matrix formalism for Lie al-gebraic tools provides a constructive method for a beam propagator in magnetic and electrical fields. The beam propagator is evaluated in according to the well known Lie algebraic tools. But in contrast to traditional approaches matrix presentation for Lie propagators bases on two di-mensional matrices.
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Механика Транспорт Комуникации - Научно списание,, 2017
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Strength of Materials, Nov 1, 1981
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Strength of Materials, Oct 1, 1981
Conclusions1.Results of tests on three boiler steels for TMF under rigid loading are more correct... more Conclusions1.Results of tests on three boiler steels for TMF under rigid loading are more correctly approximated by two straight lines on semilogarithmic coordinates of endurance to failure-stress amplitude per cycle. The upper, steeply falling straight line intersects the lower gently sloping line at some central point.2.A break is observed on thermomechanical fatigue curves on the coordinates logarithm of endurance Nf-stress range. A relationship is observed between the path of the curves for logNf(Δσ) and logNf(Δɛ) which indicate the existence of a physical prerequisite for breaks and discontinuities in thermomechanical fatigue curves.
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Technical Journal of Daukeyev University
This article examines one of the most important strokes in the tennis sport, namely, service stro... more This article examines one of the most important strokes in the tennis sport, namely, service strokes. The study covers three types of strokes: flat, slice and kick service strokes. A specially made program has been compiled in the area of MatLab, with the help of which the strongly nonlinear differential equations are integrated. These equations describe the trajectory of the tennis ball under appropriate initial conditions. All types of air resistance are included. Here, the main focus is the formation of the Magnus force. Thanks to it, the tennis ball changes its trajectory depending on the degree and type of rotation. The article is intended for a wide range of readers: scientists, tennis players, and tennis coaches.
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Applied Mathematics and Computation, 2013
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This approach based on the matrix formalism for Lie al-gebraic tools provides a constructive meth... more This approach based on the matrix formalism for Lie al-gebraic tools provides a constructive method for a beam propagator in magnetic and electrical fields. The beam propagator is evaluated in according to the well known Lie algebraic tools. But in contrast to traditional approaches matrix presentation for Lie propagators bases on two di-mensional matrices.
Bookmarks Related papers MentionsView impact
Механика Транспорт Комуникации - Научно списание,, 2017
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Strength of Materials, Nov 1, 1981
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Strength of Materials, Oct 1, 1981
Conclusions1.Results of tests on three boiler steels for TMF under rigid loading are more correct... more Conclusions1.Results of tests on three boiler steels for TMF under rigid loading are more correctly approximated by two straight lines on semilogarithmic coordinates of endurance to failure-stress amplitude per cycle. The upper, steeply falling straight line intersects the lower gently sloping line at some central point.2.A break is observed on thermomechanical fatigue curves on the coordinates logarithm of endurance Nf-stress range. A relationship is observed between the path of the curves for logNf(Δσ) and logNf(Δɛ) which indicate the existence of a physical prerequisite for breaks and discontinuities in thermomechanical fatigue curves.
Bookmarks Related papers MentionsView impact
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Technical Journal of Daukeyev University
This article examines one of the most important strokes in the tennis sport, namely, service stro... more This article examines one of the most important strokes in the tennis sport, namely, service strokes. The study covers three types of strokes: flat, slice and kick service strokes. A specially made program has been compiled in the area of MatLab, with the help of which the strongly nonlinear differential equations are integrated. These equations describe the trajectory of the tennis ball under appropriate initial conditions. All types of air resistance are included. Here, the main focus is the formation of the Magnus force. Thanks to it, the tennis ball changes its trajectory depending on the degree and type of rotation. The article is intended for a wide range of readers: scientists, tennis players, and tennis coaches.
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Applied Mathematics and Computation, 2013
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In this presentation the general motion of an asymmetrical homogeneous rigid body in a fluid envi... more In this presentation the general motion of an asymmetrical homogeneous rigid body in a fluid environment is studied. By means of a defined new theorem – The Theorem for changing the rigid body general impulse and new form of Lagrange equations, called Lagrange condensed equations, the differential equations describing the three-dimensional motion of the body in a matrix form is obtained. With a new theorem for the fluid flow of an asymmetrical rigid body, the presence of a destabilizing aerodynamic moment is proved. A new complete matrix of aerodynamic forces is defined. The spherical component of body general motion is counted with Cardan corners. The paper is entirely theoretical. It is the basis on which a second paper on the motion of an ideal rigid ellipsoid in a fluid environment is developed.
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The presentation presents the general motion of a homogeneous rigid body in a fluid environment. ... more The presentation presents the general motion of a homogeneous rigid body in a fluid environment. The body is an ellipsoid with three mutually perpendicular planes of geometric and material symmetry. The cuts of these planes with the ellipsoid represent three different ellipses. The body is accepted with six degrees of freedom. The rotation component of its general motion is counted with Cardan angles. The fluid is assumed to be immovable and it is defined by its density and invariant scalar fields of pressure and temperature. All kinds of forces and moments with which the fluid environment affects the body are accepted. A program in the MatLab-Simulink environment is developed, which identified 28 time functions and 3 projections of the mass center trajectory in the fixed coordinate planes.
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In this presentation, new equations called Condensed Lagrange equations (CLE) are defined. With t... more In this presentation, new equations called Condensed Lagrange equations (CLE) are defined. With their help, the rigid body absolute general motion is studied. The rigid body is considered to be homogeneous and unsymmetrical. CLE are similar in structure to the classical Lagrange equations from second gender, applied in vector-matrix form, but CLE are differing from them by four indicators. These differences are commented in detail in this paper. The use of the CUL is fully equivalent to the application of the theorem, called Theorem for change of the rigid body generalized impulse. Using CLE the differential equations in a matrix form, describing the rigid body absolute general motion, are obtained. CLE enrich the theory of Rigid Body Mechanics. Moreover, CLE are presented a second alternative variant of Theorem for change of the rigid body generalized impulse, they are served for verification it and they make the study completely.
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In this presentation, a rigid body absolute general motion is studied. The rigid body is assumed ... more In this presentation, a rigid body absolute general motion is studied. The rigid body is assumed as homogeneous and unsymmetrical. New additional kinetic characteristics are used. The most important of these are the following: the vector-real generalized velocity of the rigid body, the vector-generalized impulse of the rigid body and the vector-real generalized force of the rigid body. Using these new kinetic characteristics, a new theorem is defined. It is called Theorem for change of the rigid body generalized impulse. With its help, the differential equations in matrix form are obtained. These equations describe the rigid body absolute general motion. Two cases are studied - a pole that coincides and does not coincide with the rigid body mass center. The new theorem enriches the theory of Rigid Body Mechanics. The compact matrix equations provide an excellent opportunity for studying the most complicated dynamic models. They are suitable for numerical solutions with modern mathematical programs such as MatLab, MathCAD and others.
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