Applying integral approach to standardization of the quality of bottom sediments from natural waters

© 2015, Pleiades Publishing, Ltd. An integral method of quality standardization of bottom sediments based on the results of chemical, bioindication, and toxicological studies of bottom sediments has been tested as applied to the Kuibyshev Reservoir. Two types of quality standards for use in the practice of water resources management have been evaluated, including target standards (ensuring the preservation of high biodiversity) and signal (indicating to a hazardous pollution level of bottom sediments). The obtained standards have been compared with similar standards for water bodies in other countries in terms of the concentrations of metals (Zn, Cu, Ni, Cr, Pb, Cd, and Hg) and oil products in bottom sediments of the Kuibyshev Reservoir

Vertical Structure of the Outer Accretion Disk in Persistent Low-Mass X-Ray Binaries

We have investigated the influence of X-ray irradiation on the vertical structure of the outer accretion disk in low-mass X-ray binaries by performing a self-consistent calculation of the vertical structure and X-ray radiation transfer in the disk. Penetrating deep into the disk, the field of scattered X-ray photons with energy $E\gtrsim10$\,keV exerts a significant influence on the vertical structure of the accretion disk at a distance $R\gtrsim10^{10}$\,cm from the neutron star. At a distance $R\sim10^{11}$\,cm, where the total surface density in the disk reaches $\Sigma_0\sim20$\,g\,cm$^{-2}$, X-ray heating affects all layers of an optically thick disk. The X-ray heating effect is enhanced significantly in the presence of an extended atmospheric layer with a temperature $T_{atm}\sim(2\div3)\times10^6$\,K above the accretion disk. We have derived simple analytic formulas for the disk heating by scattered X-ray photons using an approximate solution of the transfer equation by the Sobolev method. This approximation has a $\gtrsim10$\,% accuracy in the range of X-ray photon energies $E<20$\,keV.Comment: 19 pages, 8 figures, published in Astronomy Letter

Backward asymmetry of the Compton scattering by an isotropic distribution of relativistic electrons: astrophysical implications

The angular distribution of low-frequency radiation after single scattering by an isotropic distribution of relativistic electrons considerably differs from the Rayleigh angular function. In particular, the scattering by an ensemble of ultra-relativistic electrons obeys the law p=1-cos(alpha), where alpha is the scattering angle; hence photons are preferentially scattered backwards. We discuss some consequences of this fact for astrophysical problems. We show that a hot electron-scattering atmosphere is more reflective than a cold one: the fraction of incident photons which become reflected having suffered a single scattering event can be larger by up to 50 per cent in the former case. This should affect the photon exchange between cold accretion disks and hot coronae or ADAF flows in the vicinity of relativistic compact objects; as well as the rate of cooling (through multiple inverse-Compton scattering of seed photons supplied from outside) of optically thick clouds of relativistic electrons in compact radiosources. The forward-backward scattering asymmetry also causes spatial diffusion of photons to proceed slower in hot plasma than in cold one, which is important for the shapes of Comptonization spectra and the time delays between soft and hard radiations coming from variable X-ray sources.Comment: 20 pages, 3 figures, to appear in Astronomy Letters, added reference

IMPROVING THE ENERGY EFFICIENCY OF AIRCOOLING DEVICES FOR COMPRESSOR STATIONS OF MAIN GAS PIPELINES

A comparative analysis of the ways to improve the energy efficiency of natural gas air coolers at compressor stations of main gas pipelines is carried out. It is shown that the most energy-efficient solution is the use of a frequency drive of the cooling apparatus fans.Проведен сравнительный анализ способов повышения энергоэффективности аппаратов воздушного охлаждения природного газа на компрессорных станциях магистральных газопроводов. Показано, что наиболее энергоэффективным решением является применение частотного привода вентиляторов аппаратов охлаждения

The profile of a narrow line after single scattering by Maxwellian electrons: relativistic corrections to the kernel of the integral kinetic equation

The frequency distribution of photons in frequency that results from single Compton scattering of monochromatic radiation on thermal electrons is derived in the mildly relativistic limit. Algebraic expressions are given for (1) the photon redistribution function, K(nu,Omega -> nu',Omega'), and (2) the spectrum produced in the case of isotropic incident radiation, P(nu -> nu'). The former is a good approximation for electron temperatures kT_e < 25 keV and photon energies hnu < 50 keV, and the latter is applicable when hnu(hnu/m_ec^2) < kT_e < 25 keV, hnu < 50 keV. Both formulae can be used for describing the profiles of X-ray and low-frequency lines upon scattering in hot, optically thin plasmas, such as present in clusters of galaxies, in the coronae of accretion disks in X-ray binaries and AGNs, during supernova explosions, etc. Both formulae can also be employed as the kernels of the corresponding integral kinetic equations (direction-dependent and isotropic) in the general problem of Comptonization on thermal electrons. The K(nu,Omega -> nu',Omega') kernel, in particular, is applicable to the problem of induced Compton interaction of anisotropic low-frequency radiation of high brightness temperature with free electrons in the vicinity of powerful radiosources and masers. Fokker-Planck-type expansion (up to fourth order) of the integral kinetic equation with the P(nu -> nu') kernel derived here leads to a generalization of the Kompaneets equation. We further present (1) a simpler kernel that is necessary and sufficient to derive the Kompaneets equation and (2) an expression for the angular function for Compton scattering in a hot plasma, which includes temperature and photon energy corrections to the Rayleigh angular function.Comment: 29 pages, 17 figures, accepted for publication in ApJ, uses emulateapj.sty, corrects misprints in previous astro-ph versio

ИСТОРИЯ РАЗВИТИЯ РОБОТИЗИРОВАННОЙ ХИРУРГИИ И ЕЕ МЕСТО В СОВРЕМЕННОЙ КОЛОПРОКТОЛОГИИ: ОБЗОР ЛИТЕРАТУРЫ

Today, the robotic surgery is a modern revolutionary technology which is opened a qualitatively new stage in the surgery development in 21-st Century. High level of precision, reliability, functionality of robotic systems can extend the technical capabilities of the surgeons and improve quality of care. Contemporary colorectal surgery couldn’t exist without new technology and the quality of life after surgery directly depends on the quality of surgical care.Сегодня, роботизированная хирургия является революционной технологией, которая открывает качественно новый этап в развитии хирургии 21-го века. Высокий уровень точности, надежности и функциональности робототехнических систем расширяет технические возможности хирургов и улучшает качество медицинской помощи.Современную колоректальную хирургию уже невозможно представить без новейших технологий и качество жизни после операции напрямую зависит от этого

Study of the Structure of the Material Obtained by Spark Plasma Sintering Chips of Dissimilar Steels

The work is devoted to the study of the structure of the iron-carbon alloy obtained by spark plasma sintering. Structural studies were carried out using the method of optical microscopy; durometric analysis was also carried out. As a result, the presence of austenitic, perlite and martensite was established. The average microhardness of the austenitic zone is 500 HV, pearlite 310 HV, the boundary zone of martensite and austenite is 750 HV.Работа посвящена исследованию структуры железоуглеродистого сплава, полученного методом искрового плазменного спекания. Структурные исследования проведены с использованием метода оптической микроскопии, также проводился дюрометрический анализ. В результате было установлено наличие аустенитна, перлита и мартенсита. Среднее значение микротвердости аустенитной зоны составляет 500 HV, перлитной — 310 HV, граничной зоны мартенсита и аустенита — 750 HV

Heating of gas inside radio sources to mildly relativistic temperatures via induced Compton scattering

Measured values of the brightness temperature of low-frequency synchrotron radiation emitted by powerful extragalactic sources reach 10^11--10^12 K. If some amount of nonrelativistic ionized gas is present within such sources, it should be heated as a result of induced Compton scattering of the radiation. If this heating is counteracted by cooling due to inverse Compton scattering of the same radio radiation, then the plasma can be heated up to mildly relativistic temperatures kT~10--100 keV. The stationary electron velocity distribution can be either relativistic Maxwellian or quasi-Maxwellian (with the high-velocity tail suppressed), depending on the efficiency of Coulomb collisions and other relaxation processes. We derive several easy-to-use approximate expressions for the induced Compton heating rate of mildly relativistic electrons in an isotropic radiation field, as well as for the stationary distribution function and temperature of electrons. We also give analytic expressions for the kernel of the integral kinetic equation (one as a function of the scattering angle and another for the case of an isotropic radiation field), which describes the redistribution of photons in frequency caused by induced Compton scattering in thermal plasma. These expressions can be used in the parameter range hnu<< kT<~ 0.1mc^2 (the formulae earlier published in Sazonov, Sunyaev, 2000 are less accurate).Comment: 22 pages, 7 figures, submitted to Astronomy Letter

TITANIUM-COPPER ALLOYS OBTAINED BY ARC MELTING IN Ar

В работе методом дугового переплава в атмосфере аргона были получены сплавы на основе титана и меди различного состава. Результаты дюрометрического анализа показали, что с увеличением концентрации меди наблюдается постепенный рост микротвердости сплавов. Было установлено, что при легировании титана медью прочностные характеристики сплавов повышаются.In research by arc melting in Ar was produced titanium-copper alloys of various concentrations. Results of microhardness test have shown that increase of copper concentration results in gradual growth of microhardness. It was established that alloying of titanium by copper improves strength properties of titanium