4,825 research outputs found
Twist tori and pseudo toric structures
Twist tori are examples of exotic monotone lagrangian tori, presented in [1].
This tree of examples grew up over the first one --- the torus , 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 , defined in [1], can be
constructed via pseudo toric considerations. Due to this one can explicitly
show that every is displaceable
Radiation-induced hydrogen transfer in metals
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
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
Study of internal structures of 9,10Be and 10B in scattering of 4He from 9Be
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
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
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
Preparation of aluminum oxide coating on carbon/carbon composites using a new detonation sprayer
A new multi-chamber cumulative detonation sprayer (MCDS) was applied to fabricate an aluminum oxide coating on carbon/carbon composites. MCDS provides heating and acceleration of ceramic micropowders by means of combustible gas mixture detonation products with a frequency of 20 Hz and above. The ceramic aluminum oxide particle kinetic energy ensures the destruction of the weakened areas on the carbon-carbon composite material surface and the incorporation of these particles into the surface layer. The following powder particles decelerate on the already fixed particles and form a ceramic coating. The formed aluminum oxide coating is characterized by high hardness and low porosity (<1%). MCDS provides the formation of a high-quality ceramic layer, which can also serve as the basis for the formation of protective heat-resistant coating
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