4,768 research outputs found

    Twist tori and pseudo toric structures

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    Twist tori are examples of exotic monotone lagrangian tori, presented in [1]. This tree of examples grew up over the first one --- the torus ΘR4\Theta \in \R^4, constructured in [2] and [3]. On the other hand, in [4] and [5] we proposed a new structure which generalizes the notion of toric structure. One calls this generalization pseudo toric structure, and several examples were given which show that certain toric symplectic manifolds can carry the structre and that certain non toric symplectic manifolds do the same. Below we show that any twist torus ΘkR2k+2\Theta^k \subset \R^{2k+2}, defined in [1], can be constructed via pseudo toric considerations. Due to this one can explicitly show that every ΘkR2k+2\Theta^k \subset \R^{2k+2} is displaceable

    Radiation-induced hydrogen transfer in metals

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    The paper presents processes of hydrogen (deuterium) diffusion and release from hydrogen-saturated condensed matters in atomic, molecular and ionized states under the influence of the electron beam and X-ray radiation in the pre-threshold region. The dependence is described between the hydrogen isotope release intensity and the current density and the electron beam energy affecting sample, hydrogen concentration in the material volume and time of radiation exposure to the sample. The energy distribution of the emitted positive ions of hydrogen isotopes is investigated herein. Mechanisms of radiation-induced hydrogen transfer in condensed matters are suggested

    Temperature Diffusivity Measurement and Nondestructive Testing Requiring No Extensive Sample Preparation and Using Stepwise Point Heating and IR Thermography

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    This chapter describes a modification to the laser flash method that allows determining temperature diffusivity and nondestructive testing of materials and constructions without cutting samples of predefined geometry. Stepwise local heating of the studied object surface at a small spot around 0.1 mm radius with simultaneous high temporary-spatial resolution infrared (IR) filming of the transient temperature distribution evolution with a thermal camera provides a wide range of possibilities for material characterization and sample testing. In case of isotropic and macroscopic homogeneous materials, the resulting transient temperature distribution is radially symmetric that renders possible to improve temperature measurement accuracy by averaging many pixels of the IR images located at the same distance from the heating spot center. The temperature diffusivity measurement can be conducted either on thin plates or on massive samples. The developed emissivity independent in plain IR thermographic method and mathematical algorithms enable thermal diffusivity measurement for both cases with accuracy around a few per cent for a wide range of materials starting from refractory ceramics to well-conducting metals. To detect defects, the differential algorithm was used. Subtracting averaged radial symmetric temperature distribution from the original one for each frame makes local inhomogeneities in the sample under study clearly discernible. When applied to crack detection in plates, the technique demonstrates good sensitivity to part-through cracks located both at the visible and invisible sides of the studied object

    Protective Effect of Meso-Tetrakis-(3,5-di-tert-butyl-4-hydroxyphenyl)porphyrin on the In Vivo Impact of Trimethyltin Chloride on the Antioxidative Defense System

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    The in vivo effect of trimethyltin chloride (Me(3)SnCl), free base meso-tetrakis(3,5-di-tert-butyl-4-hydroxyphenyl)porphyrin (R′(4)PH(2)) and their equimolar mixture, on the enzymatic activity of catalase (CAT), superoxide dismutase (SOD), and on the total content of free sulfhydryl groups has been studied in rat liver and kidney. It was demonstrated that the simultaneous treatment of tested animals with the combination of Me(3)SnCl and R′(4)PH(2) reduced the toxic impact of Me(3)SnCl

    Study of internal structures of 9,10Be and 10B in scattering of 4He from 9Be

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    A study of inelastic scattering and single-particle transfer reactions was performed by an alpha beam at 63 MeV on a 9$Be target. Angular distributions of the differential cross sections for the 9Be(4He,4He')9Be*, 9Be(4He,3He)10Be and 9Be(4He,t)10B reactions were measured. Experimental angular distributions of the differential cross sections for the ground state and a few low-lying states were analyzed in the framework of the optical model, coupled channels and distorted-wave Born approximation. An analysis of the obtained spectroscopic factors was performed.Comment: 16 pages, 7 figures, 3 tables, regular paper, mispritns are corrected in new versio

    Formation of high-carbon abrasion-resistant surface layers when high-energy heating by high-frequency currents

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    The paper shows the possibility of carburization of low-carbon steel surface layers using high-frequency currents. The mathematical modeling of carburization using high-energy heating by high-frequency currents (HEH HFC) has been carried out, the temperature fields formed during the given processing have been calculated, as well as the structural changes in the surface layers have been simulated. The features of the structure formation in the surface layers of low-carbon steel after carburizing via HEH HFC have been determined by optical and scanning microscopy, which is confirmed by the computational models. The rational mode of fusion via HEH HFC has also been determined (power density of the source q[s]=(1.5...4.0)•10{8} W m{-2}, (the relative travel speed of parts V[p]=5 ... 100 mm /sec), with forming the compressive retained stresses in the surface layer ([sigma][RS]=-300...-400 MPa)
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