Singular value decomposition for the 2D fan-beam Radon transform of tensor fields

In this article we study the fan-beam Radon transform ${\cal D}_m$ of symmetrical solenoidal 2D tensor fields of arbitrary rank $m$ in a unit disc $\mathbb D$ as the operator, acting from the object space ${\mathbf L}_{2}(\mathbb D; {\bf S}_m)$ to the data space $L_2([0,2\pi)\times[0,2\pi)).$ The orthogonal polynomial basis ${\bf s}^{(\pm m)}_{n,k}$ of solenoidal tensor fields on the disc $\mathbb D$ was built with the help of Zernike polynomials and then a singular value decomposition (SVD) for the operator ${\cal D}_m$ was obtained. The inversion formula for the fan-beam tensor transform ${\cal D}_m$ follows from this decomposition. Thus obtained inversion formula can be used as a tomographic filter for splitting a known tensor field into potential and solenoidal parts. Numerical results are presented.Comment: LaTeX, 37 pages with 5 figure

Investigation of the peculiarities of oxidation of Ti/Al nanoparticles on heating to obtain TiO2/Al2O3 composite nanoparticles

The creation of new nanomaterials with improved characteristics, as well as the development of new approaches to obtain such materials is an urgent task in science and technology. One of the promising directions in obtaining improved nanomaterials is the use of precursors in the form of multicomponent metal nanoparticles. Thermal oxidation of bimetallic Ti/ Al nanoparticles obtained by electrical explosion of wires was investigated in this work. Ti/Al nanoparticles have been found to be completely oxidized with the formation of composite TiO2/ Al2O3 nanoparticles after calcination at 900 °C. The formation of TiO2 phase with a rutile structure on heating to 500 °C, and the formation of TiO2 phases with a rutile and anatase structure, as well as α-Al2O3 on heating to 700 °C have been established, in addition to the residue of unoxidized metals. Complete oxidation of Ti/Al nanoparticles occurs when heated to 900 °C. The photochemical activity of TiO2/ Al2O3 composite nanoparticles obtained at 900 °C was studied. The degradation of methyl orange dye reached 55% under UV irradiation for 120 min

Preparation of nano/micro-bimodal Ti/Al/(Mo, W, Cu) powders by simultaneous electrical explosion of dissimilar metal wires

Novel mixtures of micro- and nanoparticles have been obtained by simultaneous electrical explosion of three intertwisted wires (EEW). The possibility of obtaining of titanium‑aluminum micro- and nanoparticles alloyed with molybdenum, tungsten and copper by the electrical explosion of Ti/Al/(Mo, W, Cu – up to 6 at. %) wires has been shown. Spherical particle with sizes from 20 nm to 7 μm are formed under condition of introducing the electric energy at the level of 0.57–0.77 of the total sublimation energy. The mass content of particles with sizes less than 100 nm does not exceed 10%. The phase composition of powders includes double and triple intermetallic phases, titanium oxide (TiO) as well as phases of the initial metals. The study of the phase composition of bulk materials obtained by sintering powders Ti-Al-Mo, Ti-Al-W and Ti-Al-Cu for 2 h at 1000 °C showed the increase in the content of intermetallic phases, providing enhanced physical and mechanical properties of the titanium‑aluminum alloys. The results of the studies show that the obtained powders alloys can be used to produce feedstocks of TiAl alloys

Synthesis of Ti–Al bimodal powder for high flowability feedstock by electrical explosion of wires

In this research, Ti–Al bimodal powders were produced by simultaneous electrical explosion of titanium and aluminum wires. The resulting powders were used to prepare powder–polymer feedstocks. Material characterization involving X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), and melt flow index (MFI) determination were carried out to characterize bimodal powders obtained and evaluate the influence of the powder composition on the feedstock flowability. The bimodal distribution of particles in powders has been found to be achieved at a current density of 1.2 × 107 A/cm2 (the rate of energy input is 56.5 J/µs). An increase in the current density to 1.6 × 107 A/cm2 leads to a decrease in the content of micron particles and turning into a monomodal particle size distribution. The use of bimodal powders for powder–polymer feedstocks allows to achieve higher MFI values compared with monomodal powders. In addition, the use of electroexplosive synthesis of bimodal powders makes it possible to achieve a homogeneous distribution of micro- and nanoparticles in the feedstock

Geometric optics with atomic beams scattered by a detuned standing laser wave

We report on theoretical and numerical study of propagation of atomic beams crossing a detuned standing-wave laser beam in the geometric optics limit. The interplay between external and internal atomic degrees of freedom is used to manipulate the atomic motion along the optical axis by light. By adjusting the atom-laser detuning, we demonstrate how to focus, split and scatter atomic beams in a real experiment. The novel effect of chaotic scattering of atoms at a regular near-resonant standing wave is found numerically and explained qualitatively. Some applications of the effects found are discussed

Energy dependence of ϕ meson production at forward rapidity in pp collisions at the LHC

The production of $\phi$ mesons has been studied in pp collisions at LHC energies with the ALICE detector via the dimuon decay channel in the rapidity region $2.5< y < 4$. Measurements of the differential cross section $\mathrm{d}^2\sigma /\mathrm{d}y \mathrm{d}p_{\mathrm {T}}$ are presented as a function of the transverse momentum ($p_{\mathrm {T}}$) at the center-of-mass energies $\sqrt{s}=5.02$, 8 and 13 TeV and compared with the ALICE results at midrapidity. The differential cross sections at $\sqrt{s}=5.02$ and 13 TeV are also studied in several rapidity intervals as a function of $p_{\mathrm {T}}$, and as a function of rapidity in three $p_{\mathrm {T}}$ intervals. A hardening of the $p_{\mathrm {T}}$-differential cross section with the collision energy is observed, while, for a given energy, $p_{\mathrm {T}}$ spectra soften with increasing rapidity and, conversely, rapidity distributions get slightly narrower at increasing $p_{\mathrm {T}}$. The new results, complementing the published measurements at $\sqrt{s}=2.76$ and 7 TeV, allow one to establish the energy dependence of $\phi$ meson production and to compare the measured cross sections with phenomenological models. None of the considered models manages to describe the evolution of the cross section with $p_{\mathrm {T}}$ and rapidity at all the energies.publishedVersio

Preparation and Adsorption Properties of Nanostructured Composites Derived from Al/Fe Nanoparticles with Respect to Arsenic

Composite nanostructures containing iron in different forms exhibit a high adsorption capacity with respect to arsenic. The aim of our study was to investigate the adsorption activity of an adsorbent composite prepared by the oxidation of bimetallic Al/Fe nanoparticles under different conditions. Depending on the oxidation conditions, nanostructures with different morphologies in the form of nanosheets, nanoplates and nanorods with different compositions and textural characteristics could be obtained. The nanostructures obtained had a positive zeta potential and were characterized by a high specific surface area: 330 m2/g for the AlOOH/FeAl2 nanosheets; 75 m2/g for the AlOOH/Fe2O3/FeAl2 nanoplates; and 43 m2/g for the Al(OH)3/FeAl2 nanorods. The distribution of an FeAl2 intermetallide over the surface of the AlOOH nanostructures led to an increase in arsenic adsorption of 25% for the AlOOH/FeAl2 nanosheets and of 34% for the AlOOH/Fe2O3/FeAl2 nanoplates and Al(OH)3/FeAl2 nanorods. The adsorption isotherms matched most preciously to the Freundlich model. This fact indicated the energy heterogeneity of the adsorbent surface and multilayer adsorption. The nanostructures studied can be used to purify water contaminated with arsenic

Product Lifecycle Support for Radioelectronic Production at JSC «SPE «Radiosvyaz»

Рассмотрены проблемы организации информационного сопровождения подготовки производства радиоэлектронной аппаратуры на предприятии ОАО «НПП «Радиосвязь».Проанализированы проблемы,возникающие при внедрении информационных средств поддержки управления процессом производства высокотехнологичной продукции. Указаны особенности реализации единого информационного пространства для поддержки процессов организации производства изделий радиоэлектроники. Результаты работы рассматривают практические аспекты внедрения комплексного подхода к автоматизации и могут быть использованы на предприятиях радиоэлектронной промышленности.The problems of PLM-management of electronic equipment production at JSC «SPE «Radiosvyaz» are considered. The problems arising in the implementation of information management tools to support the process of high-tech products. Also analyzed problems with implementation of PLM-systems in production management processes of high-tech products. The implementation peculiarities of common information space to organization production processes support of electronics products are given. Considering the results of the practical aspects of implementing an integrated approach to automation can be used in enterprises of electronic industr