ON FORMATION OF ELECTRICALLY CONDUCTIVE PHASES UNDER ELECTROTHERMAL ACTIVATION OF FERRUGINOUS CARBONATES

Purpose. Study of the formation of an electrically conductive phase in carbonates using siderite as an example and determination of the temperature dependence of its formation and silicon content during simultaneous heating and the action of a weak electric field. Methodology. Analysis and generalization of the results of experimental studies. Physicochemical analytical studies have been performed using electron and optical microscopy, petrographic and X-ray phase analysis, thermogravimetric analysis and differential scanning calorimetry, and gas chromatography. Phase equilibria in the “iron oxides – carbon – carbon oxides” system have been evaluated using data on the standard change in the Gibbs energy Evaluation. Findings. Formation of electrically conductive phases in siderite has been studied. The dependence of new phase formation on heating and the magnitude of the electric field strength have been determined. The regularities of the change in threshold temperatures of phase transitions in samples of siderite and calcite containing silicon impurities have been established. Originality. Due to the thermally stimulated increase in the concentration of mobile charge carriers in intergranular space, the electric field of point charges takes the prominent part in the formation of the end product of chemical reactions. The additional effect of electric current on the increasing destabilization of chemical bonds between surface atoms leads to the formation and transport of ions, to a decrease in the energy barrier of nuclei formation of the electrically conductive phase near the active centres. The abrupt increase in electrical conductivity is due to the spontaneous formation of the nuclei of a new phase and the transition of ionic conductivity to a mixed one or an electronic one primarily. A composite semiconductor is formed as a result of electrothermal activation of siderite. This semiconductor consists of a matrix-semiconductor representing the initial mineral and is penetrated by parallel-oriented highconductivity threads. Practical value. Experimental results show that such processes occurring in rock are quite real under the conditions of the earth’s crust, and the physical values of thermodynamic quantities (factors of metamorphism) are sometimes overestimated significantly in the interpretation of various geological events

Complex for Modeling the Reliability of Reactor Plant Systems by the Monte Carlo Method

The article considers the main models incorporated in the developed software package for modeling reliability indicators of nuclear reactor unit (RF) complex technical systems by the Monte Carlo method. Approaches to organization of system state determination on the layout basis into groups, principles of accounting for dependent failures and incomplete recovery are described

Modernization of the Target Design for Molybdenum Production

The following work is a comparative analysis of two target designs for Molybdenum-99 production. Important parameters for their usage are their thermal-hydraulic properties. The considered target designs can be used in a research reactor of basin type. The research channel, where the target is being installed, does not possess high static pressure; therefore, the target should not cause the coolant boiling during operation. The more fissile material in the target, the higher the expected isotope producing and at the same time the energy release. The main task of construction modernization of the target is to increase the production of the necessary radioisotope in the normal removal of heat from the walls of the target sleeve. Comparative analysis is carried out for targets of the cylindrical type

Investigation of Check Valve Aerodynamic Characteristics in Different Operating Modes

The paper presents a computational study of the NPP ventilation system check valve aerodynamics, namely, a numerical simulation of the air flowing through the open valve with the subsequent determination of the relationship between the reactive torque acting on the valve closure axles and the input air velocity.This numerical simulation of the air flowing through the check valve was performed using the ANSYS CFX program. In the computation, different operating modes of the check valve were considered when the air flow was passing through it. The valve operating modes were set depending on changes in the input air velocity. As a result of aerodynamic computation, the values of pressure and velocity components were obtained over the entire valve volume.Reactive forces were calculated in the ANSYS Mechanical program. The reactive forces acting on the valve body form a torque at the gate axles. When adjusting the check valve to the actual flow rate, it is necessary to know this torque value and compensate for it. As a result of a series of computations of reactive forces, a relationship was found between the torque value of the valve’s working element axles and the input air velocity.

Computational Analysis of the Shutdown of One MCP of VVER-1000 During Operation of the Reactor Facility at Nominal Power

The article considers results of the computational analysis of process with a disturbance in the operation of VVER-1000 reactor facility, caused by the de-energizing of a single Main Circulation Pump (MCP-195).Calculations of de-energizing of the MCP were made with the CORSAR/GP software package developed by Federal State Unitary Enterprise "Alexandrov RESE". This software package is a contour code which allows making calculations of emergency situations taking into account the operation of various systems, including safety systems. CORSAR/GP is certified and verified for facilities with water-cooled reactors including VVER-1000.Developed nodalization scheme (computational scheme) of the first circuit of VVER-1000 allows adding or excluding the operation of protective safety systems and can also be used for a computational analysis of other disturbances of normal operation.To perform the calculations parameters of the core were chosen to ensure conservative results for the parameters determining the current state of the reactor facility (fuel temperature, boiling point, etc.).The computational analysis showed that in case of de-energizing of a single MCP when the reactor is operated at nominal power criteria describing the safety of the facility are fulfilled, protective automatic actions of safety systems transfer the reactor facility to a controlled safe state

Bethe-Sommerfeld conjecture for periodic operators with strong perturbations

We consider a periodic self-adjoint pseudo-differential operator $H=(-\Delta)^m+B$, $m>0$, in $\R^d$ which satisfies the following conditions: (i) the symbol of $B$ is smooth in \bx, and (ii) the perturbation $B$ has order less than $2m$. Under these assumptions, we prove that the spectrum of $H$ contains a half-line. This, in particular implies the Bethe-Sommerfeld Conjecture for the Schr\"odinger operator with a periodic magnetic potential in all dimensions.Comment: 61 page

Complete asymptotic expansion of the integrated density of states of multidimensional almost-periodic pseudo-differential operators

We obtain a complete asymptotic expansion of the integrated density of states of operators of the form H =(-\Delta)^w +B in R^d. Here w >0, and B belongs to a wide class of almost-periodic self-adjoint pseudo-differential operators of order less than 2w. In particular, we obtain such an expansion for magnetic Schr\"odinger operators with either smooth periodic or generic almost-periodic coefficients.Comment: 47 pages. arXiv admin note: text overlap with arXiv:1004.293

Scott correction for large atoms and molecules in a self-generated magnetic field

We consider a large neutral molecule with total nuclear charge $Z$ in non-relativistic quantum mechanics with a self-generated classical electromagnetic field. To ensure stability, we assume that Z\al^2\le \kappa_0 for a sufficiently small $\kappa_0$, where \al denotes the fine structure constant. We show that, in the simultaneous limit $Z\to\infty$, \al\to 0 such that \kappa =Z\al^2 is fixed, the ground state energy of the system is given by a two term expansion $c_1Z^{7/3} + c_2(\kappa) Z^2 + o(Z^2)$. The leading term is given by the non-magnetic Thomas-Fermi theory. Our result shows that the magnetic field affects only the second (so-called Scott) term in the expansion

ХИРУРГИЧЕСКАЯ КОРРЕКЦИЯ ДЕФОРМАЦИИ ПОЗВОНОЧНИКА ПРИ ИДИОПАТИЧЕСКОМ СКОЛИОЗЕ: ИСТОРИЯ И СОВРЕМЕННОЕ СОСТОЯНИЕ (ОБЗОР ЛИТЕРАТУРЫ)

The article presents the historical and contemporary aspects of the state of the question correct scoliosis spine with dorsal and ventral spinal systems. The variants of spinal deformity correction method from Harrington to modern surgical techniques using both hook and metal screw. Detailed technological aspects of surgical interventions for the correction of spinal deformity using a variety of spinal structures. A comparative estimate of the correction of spinal deformity, the impact on the result of the initial mobility of the spine, level metallofiksatsii vertebral-motor segment, as well as the degree of true derotation vertebrae at the top of the curvature in a variety of surgical procedures. Describes the advantages and disadvantages of options for surgery.В литературном обзоре освещаются история и современное состояние проблемы коррекции сколиотической деформации позвоночника с использованием дорзальных и вентральных спинальных систем. Рассмотрены варианты исправления деформации позвоночника начиная с метода Харрингтона и заканчивая современными хирургическими технологиями с применением крюковых и винтовых металлоконструкций. Дан обзор технологических особенностей оперативных вмешательств при коррекции деформации позвоночника с использованием различных спинальных конструкций, описаны их достоинства и недостатки

Second order semiclassics with self-generated magnetic fields

We consider the semiclassical asymptotics of the sum of negative eigenvalues of the three-dimensional Pauli operator with an external potential and a self-generated magnetic field $B$. We also add the field energy $\beta \int B^2$ and we minimize over all magnetic fields. The parameter $\beta$ effectively determines the strength of the field. We consider the weak field regime with $\beta h^{2}\ge {const}>0$, where $h$ is the semiclassical parameter. For smooth potentials we prove that the semiclassical asymptotics of the total energy is given by the non-magnetic Weyl term to leading order with an error bound that is smaller by a factor h^{1+\e}, i.e. the subleading term vanishes. However, for potentials with a Coulomb singularity the subleading term does not vanish due to the non-semiclassical effect of the singularity. Combined with a multiscale technique, this refined estimate is used in the companion paper \cite{EFS3} to prove the second order Scott correction to the ground state energy of large atoms and molecules.Comment: Small typos corrected on Sep 24, 201