Tubular initial conditions and ridge formation

The 2D azimuth & rapidity structure of the two-particle correlations in relativistic A+A collisions is altered significantly by the presence of sharp inhomogeneities in superdense matter formed in such processes. The causality constraints enforce one to associate the long-range longitudinal correlations observed in a narrow angular interval, the so-called (soft) ridge, with peculiarities of the initial conditions of collision process. This study's objective is to analyze whether multiform initial tubular structures, undergoing the subsequent hydrodynamic evolution and gradual decoupling, can form the soft ridges. Motivated by the flux-tube scenarios, the initial energy density distribution contains the different numbers of high density tube-like boost-invariant inclusions that form a bumpy structure in the transverse plane. The influence of various structures of such initial conditions in the most central A+A events on the collective evolution of matter, resulting spectra, angular particle correlations and v_n-coefficients is studied in the framework of the HydroKinetic Model (HKM).Comment: 18 pages, 6 figures, the paper to be published in Advances of High Energy Physics (2013, in press

Quantitative assessment of pinning forces and the superconducting gap in NbN thin films from complementary magnetic force microscopy and transport measurements

Epitaxial niobium-nitride thin films with a critical temperature of Tc=16K and a thickness of 100nm were fabricated on MgO(100) substrates by pulsed laser deposition. Low-temperature magnetic force microscopy (MFM) images of the supercurrent vortices were measured after field cooling in a magnetic field of 3mT at various temperatures. Temperature dependence of the penetration depth has been evaluated by a two-dimensional fitting of the vortex profiles in the monopole-monopole model. Its subsequent fit to a single s-wave gap function results in the superconducting gap amplitude Delta(0) = 2.9 meV = 2.1*kB*Tc, in perfect agreement with previous reports. The pinning force has been independently estimated from local depinning of individual vortices by lateral forces exerted by the MFM tip and from transport measurements. A good quantitative agreement between the two techniques shows that for low fields, B << Hc2, MFM is a powerful and reliable technique to probe the local variations of the pinning landscape. We also demonstrate that the monopole model can be successfully applied even for thin films with a thickness comparable to the penetration depth.Comment: 6 pages, 6 figures, 2 table

CRYSTALLIZATION KINETICS OF POLYMERIC NANOCOMPOSITES BASED ON POLYAMIDE 12 MODIFIED BY Cr2O3 NANOPARTICLES

In situ polymerization method is used for obtaining polymeric composites based on polyamide12 matrix (PA 12), filled with Cr2O3 nanoparticles. The carried out researches result in synthesis method development for polymeric nanocomposites based on PA 12 matrix filled with nano-sized Cr2O3magnetic particles providing uniform embedding of the filler into polymeric matrix without formation of nanoparticles agglomerates. Mechanical tests on samples compression are carried out. It is shown that mechanical properties of polymeric composites (Young’s modulus, durability limit) are decreased for 20-30 % as compared with not modified PA 12 synthesized by means of the chosen method. The influence of the filler on crystallization morphology and kinetics of polymeric nanocomposites is determined by electron microscopy and differential scanning calorimetry. The values of crystallization degree, crystallization rate constant for different supercooling intervals and parameters of Avrami equation are obtained. The initial nucleation is shown to be going on according to non-thermal mechanism, and nanoparticles are not the germs of crystallization. It is stated that nanoparticles are embedded into polymeric matrix and uniformly allocated in crystallites. Research results can find their application at creation of electric and magnetic fields, micro-sized mechanical devices, and at development of new materials for 3D printers

Спосіб визначення релаксаційного зусилля тушок риби

There have been repeated cases of fish sales during the spawning period in the Ukrainian market, which consumer value is much lower, and fish re-freezing products. The aforementioned methods of abuse can be identified by commodity experts, while ordinary consumers, unfortunately, often cannot independently determine the quality of the fish. The basis of the vast majority of sensory checks of the elastic properties of fish is the process of compressing the product. The advantage of determining the surface relaxation rate is that it is non-destructive testing and the product appearance of the product after the examination does not change. However, this method requires some practical experience and depends essentially on the qualifications of an expert. The method and equipment for instrumental assessment of relaxation compression deformation force to define structural and mechanical properties of fish is given; it makes possible to minimize the experimenter influence on the results and obtain a quantitative value of relaxation speed at anytime in the experiment. The method of investigation of relaxation force and the rate of fish carcasses relaxation was theoretically grounded. A 3D-diagram of force that act on the indenter while pressing the surface of white cupid carcass is given. The type of dynamometer and measuring device for fixation of relaxation force dynamics is grounded. There was developed the sensor for determining the dynamics of the relaxation force with a constant depth of lowering of the indenter; scheme and photo of it is given. The mathematical models of relaxation velocity at axial deformation of compression and tension were constructed. The proposed method for quantifying the relaxation rate involves the construction of a compression deformation curve in the second of pressing a fish carcass and determining their angle of inclination. Based on the mathematical analysis of the deformation curves, it was found that for chilled meat of white cupid for 8 hours of storage, the relaxation rate at strain by 33% is greater than for the compression deformation; the primary force upon pressing on the product is 23% greater than when the specimen is subjected to a similar cross-sectional area. The developed methodology and system allows to determine the relaxation force when squeezing a fish sample just like a commodity science expert does and make quantitative assessment of its structural and mechanical properties.На ринку України неодноразово спостерігалися випадки продажів риби нерестового періоду, споживча цінність якої є значно нижчою, та рибних продуктів повторної заморозки. Вищезгадані способи зловживань можуть бути ідентифіковані експертами-товарознавцями, тоді як пересічні споживачі нажаль, частіше не можуть самостійно визначити якість риби. В основу переважної більшості сенсорних перевірок пружних властивостей риби покладено процес стискання продукту. Перевагою визначення швидкості релаксації поверхні є те, що це неруйнівний контроль і товарний вигляд продукту після експертизи не змінюється. Проте такий спосіб вимагає певного практичного досвіду та суттєво залежить від кваліфікації експерта. Запропоновано методику та обладнання для інструментальної оцінки релаксаційного зусилля деформації стиску для визначення структурно-механічних властивостей риби, що дозволяє мінімізувати вплив експериментатора на результати та отримати кількісні значення швидкості релаксації в будь який момент часу експерименту. Теоретично обґрунтовано спосіб дослідження релаксаційного зусилля та швидкості релаксації тушок риби. Наведено тривимірну схему сил, що діють на індентор під час натискання на поверхню тушки білого амура, враховуючи зсув шарів м’язів. Обґрунтовано тип динамометра та вимірювального приладу для фіксації динаміки релаксаційного зусилля. Створено датчик для визначення динаміки релаксаційного зусилля із сталою глибиною опускання індентора, наведено його схему та фотографію.&nbsp; Встановлено відмінність між швидкістю релаксації при деформації стиску та розтягу. Побудовано математичні моделі швидкості релаксації при осьовій деформації стиску та розтягу. Запропонована методика кількісної оцінки швидкості релаксації передбачає побудову дотичних до кривої деформації стиску на другій секунді натискання на тушку риби. Та&nbsp; визначення їх кута нахилу. На підставі математичного аналізу кривих деформації, встановлено, що для охолодженого м’яса білого амура 8 годин зберігання швидкість релаксації при деформації розтягу на 33% більшою ніж при деформації стиску, початкове зусилля при надавлюванні на продукт на 23,5% більше ніж при розтягуванні зразка аналогічної площі поперечного перерізу. Розроблена методика та система дозволяє визначити релаксаційне зусилля при здавлюванні зразка риби подібно до того, як це робить товарознавець-експерт та кількісно оцінити його структурно-механічні властивості

Vortex phases in mesoscopic cylinders with suppressed surface superconductivity

Vortex structures in mesoscopic cylinder placed in external magnetic field are studied under the general de Gennes boundary condition for the order parameter corresponding to the suppression of surface superconductivity. The Ginzburg-Landau equations are solved based on trial functions for the order parameter for vortex-free, single-vortex, multivortex, and giant vortex phases. The equilibrium vortex diagrams in the plane of external field and cylinder radius and magnetization curves are calculated at different values of de Gennes "extrapolation length" characterizing the boundary condition for the order parameter. The comparison of the obtained variational results with some available exact solutions shows good accuracy of our approach.Comment: RevTex, 11 pages, 10 figure

Symmetry and disorder of the vitreous vortex lattice in an overdoped BaFe_{2-x}Co_xAs_2 superconductor: Indication for strong single-vortex pinning

The disordered flux line lattice in single crystals of the slightly overdoped aFe_{2-x}Co_xAs_2 (x = 0.19, Tc = 23 K) superconductor is studied by magnetization measurements, small-angle neutron scattering (SANS), and magnetic force microscopy (MFM). In the whole range of magnetic fields up to 9 T, vortex pinning precludes the formation of an ordered Abrikosov lattice. Instead, a vitreous vortex phase (vortex glass) with a short-range hexagonal order is observed. Statistical processing of MFM datasets lets us directly measure its radial and angular distribution functions and extract the radial correlation length \zeta. In contrast to predictions of the collective pinning model, no increase in the correlated volume with the applied field is observed. Instead, we find that \zeta decreases as 1.3*R1 ~ H^(-1/2) over four decades of the applied magnetic field, where R1 is the radius of the first coordination shell of the vortex lattice. Such universal scaling of \zeta implies that the vortex pinning in iron arsenides remains strong even in the absence of static magnetism. This result is consistent with all the real- and reciprocal-space vortex-lattice measurements in overdoped as-grown aFe_{2-x}Co_xAs_2 published to date and is thus sample-independent. The failure of the collective pinning model suggests that the vortices remain in the single-vortex pinning limit even in high magnetic fields up to 9 T.Comment: 11 pages, 6 figure

Symmetry and disorder of the vitreous vortex lattice in an overdoped BaFe_{2-x}Co_xAs_2 superconductor: Indication for strong single-vortex pinning

The disordered flux line lattice in single crystals of the slightly overdoped aFe_{2-x}Co_xAs_2 (x = 0.19, Tc = 23 K) superconductor is studied by magnetization measurements, small-angle neutron scattering (SANS), and magnetic force microscopy (MFM). In the whole range of magnetic fields up to 9 T, vortex pinning precludes the formation of an ordered Abrikosov lattice. Instead, a vitreous vortex phase (vortex glass) with a short-range hexagonal order is observed. Statistical processing of MFM datasets lets us directly measure its radial and angular distribution functions and extract the radial correlation length \zeta. In contrast to predictions of the collective pinning model, no increase in the correlated volume with the applied field is observed. Instead, we find that \zeta decreases as 1.3*R1 ~ H^(-1/2) over four decades of the applied magnetic field, where R1 is the radius of the first coordination shell of the vortex lattice. Such universal scaling of \zeta implies that the vortex pinning in iron arsenides remains strong even in the absence of static magnetism. This result is consistent with all the real- and reciprocal-space vortex-lattice measurements in overdoped as-grown aFe_{2-x}Co_xAs_2 published to date and is thus sample-independent. The failure of the collective pinning model suggests that the vortices remain in the single-vortex pinning limit even in high magnetic fields up to 9 T.Comment: 11 pages, 6 figure

The problems of economic accounting components disunity in Russian companies in the economy digitalisation

The problematic of the study is determined by the business accounting components disunity in Russian companies revealed as the result of authors’ consulting practice. The purpose of the article was to substantiate the interrelation of accounting components (accounting, tax, management and statistical types of accounting) and to define the lines of research needed for the formation of uniformity and comparability of data. It is also necessary to implement the tasks of digitalisation in economy and to generate information for internal and external interested users. Based on the analysis of legislation on accounting, taxation, management accounting and state statistical observation, the absence in concept of the statistical information for organisations and the current system of statistical accounting in organisations has been established. Detected gap, in the absence of internal and external control, leads to a loss of statistical reporting reliability. It not only determined the relevance of the study, but it creates a precedent for discussion about the advisability of creating in an organisation a separate set of statistical information from accounting, designed to fill in and control reports of federal statistical observation