Journal of Theoretical and Applied Mechanics

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		Langrangean Coordinate Determination in Case of Unsteady Oscillations of a Rigid Rotor with Sliding Bearings V. Kortenska High. Inst. Arch. Civ. Eng., 1 Hr. Smirnenski Blvd., Sofia The paper presents some results of the author's investigations concerning unsteady oscillations of a rigid rotor with sliding bearings. Small oscillations of the rotor equilibrium state are considered. It is used a method which is developed by the author when the introduction of a small parameter and the realization of certain inner resonances have been possible. JTAM, Sofia, vol. 17 Issue 4 pp. 009-013 (1986)

		Synthesis of the Primary Pitch Cones of Hyperbolic Clearings, One of Them Being of Cylindric Form V. Abadjiev Inst. Mech. Biomech., Bulg. Acad. Sci., BI. 8 A survey of the known approaches for synthesis of primary pitch cones is made. The investigation has allowed to find algorithms for calculating the geometry of the primary pitch cones of all hyperbolic gearings, when one of them is of cylindric form. JTAM, Sofia, vol. 17 Issue 4 pp. 014-018 (1986), [Full Article]

		Optimization Design of an Accumulating Boiler G. Georgiev, J. Popov, St. Bushev, B. Zlatev, V. Kovatchev, T. Stoichev Sci. Ind. Center 'Technology of Metals', 53 Chapaev Str., Sofia What is proposed is an optimization method for the design of an accumulating electric boiler with a view to minimum consumption of electrical energy and invested materials. The optimization algorithm is based on a mathematical model of heat and mass transfer processes in the boiler and the installation that have been described in a previous paper. It is given the block-scheme of the algorithm. Optimum values of the constructive parameters are obtained by means of a program realization. JTAM, Sofia, vol. 17 Issue 4 pp. 019-026 (1986)

		Hydrodynamic Numerical Study of a Column Chemical Contactor G. Angelov¹, G. Muratet², I. Zheleva³ ¹Central Lab. Chem. Eng., Bulg. Acad. Sc ²Inst. Chem. Eng., Toulouse, France ³Inst. Mech. Biomech., Bulg. Acad. Sci., Bl. 8 It is considered a vertical column apparatus with a cylindrical body that has been divided into identical stages by ring and disc bar alternating. The incompressible fluid is examined numerically by means of the current function in the Navier-Stokes equations. The authors obtain the velocity vector field and the stream lines: for various Reynolds numbers. The results simulate the formation and the evolution of a vortex stream which is in good agreement with the experimental observations of a real column. JTAM, Sofia, vol. 17 Issue 4 pp. 027-034 (1986)

		Application of Hopkinson Rod to the Investigation of Neutron Emission Influence on Steel Dynamic Characteristics I. Buchar¹, F. DuÅ¡ek¹, St. VodeniÄarov ¹Inst. Met. Res., Acad. Sci., Barno, Czechoslovakia ²Inst. Met. Res. Techn., Bulg. Acad Sci., Sofia The paper sets forth an experimental method and the investigation results when some steels have been subjected to neutron radiation emission. The mechanical characteristics are studied specially at high speed loading that has been realized by the experimental installation "Hopkinson rod". JTAM, Sofia, vol. 17 Issue 4 pp. 035-039 (1986), [Full Article]

		Investigation of Neutron Irradiated Steels by the Method of the Hopkinson Measuring Rod F. Dushek¹, St. Vodenicharov² ¹Inst. Met. Res., Acad. Sci., Barno, Czechoslovakia ²Inst. Met. Res. Techn., Bulg. Acad. Sci., Sofia A method and experimental technics are proposed to estimate steel tendency to tender fracture. The absorbing of tension waves is used as a base. The mechanical properties of the material have been estimated together with the tension wave energy during the loading which is a model of a metal matrix one in the tender crack field of propagation. Some of the selected steels have been irradiated by neutrons with integral doses 10^-19 N. cm^-2. The experiments are possible in case of reinforced precautions only because of the small models and the intensity of the secondary emission which does not exceed 0.5 m sec. JTAM, Sofia, vol. 17 Issue 4 pp. 040-049 (1986)

		Stabilized Rotating Oscillations in Machine Aggregates with Variable Mass Characteristics N. Minchev, S. Kazandjiev High Inst. Mech. Elects. Eng., Varna What is considered in the paper is the mathematical foundation of a method to calculate rotating oscillations at steady regimes of machine aggregates with variable mass characteristics. The last are out of the zones of parametric resonances. The basic characteristic resonances have been analyzed, thus defining the corresponding conditions for oscillation extremity. Possibilities are considered, as well, for a simplification of the proposed mathematical method. JTAM, Sofia, vol. 17 Issue 4 pp. 050-060 (1986)

		Initiation of Crack Propagation by the J_R-Curved Line Method K. Minchev Sci. Ind. Center "Technology of Metals", 53 Chapaev Str., Sofia An application of the J_R-curved line method to initiate crack propagation is considered in the paper. The crack start moment is experimentally defined for some constructive steels by J-integral values. The Landes-Begley method and the method of elastic pliability test are used for the purpose. The results are compared and some conclusions are made concerning the use of the J_R-curved line method. JTAM, Sofia, vol. 17 Issue 4 pp. 061-064 (1986)