A method for calculating the optimal consumption of the resource control of perturbed dynamic systems. This method includes both normal and singular solutions. According to the method proposed the problem is subdivided into three independent tasks: 1) a consideration of the effects of perturbations on the system; 2) computation of the optimal control structure; 3) computation of the switching moments of optimal control. A consideration of the effects of perturbations on the system and transfer to a non-zero final state are reduced to the transformation of the initial and final states of the systems. The structure calculation is based on the relation between deviations in the initial conditions of the conjugate systems and deviations of the phase trajectory at the completion instant. An iterative algorithm has been developed, its characteristics being considered. The results of modeling and numerical calculations are given.
E.A. Bondarev1, A.F. Voevodin2, K.K. Argunova1, I.I. Rozhin1 1Institute of Oil and Gas Problems of Siberian Branch of Russian Academy of Sciences, Oktyabrskaya, 1, Yakutsk, Russia, 677980 2Lavrentyev Institute of Hydrodynamics, Siberian Branch of the Russian Academy of Sciences, Lavrentiev st., 15, Novosibirsk, 630090
Keywords: уравнение состояния, природный газ, гиперболические уравнения, equation of state, natural gas, hyperbolic equations
By comparison with reliable experimental data in a wide range of pressure and temperature, it has been shown that the Redlich-Kwong equation of state appropriately reflects all the characteristics of the coefficient of compressibility, the throttling factor and the normalized difference of specific isobaric and isochoric heat capacities. It has been found that this equation corresponds to the inequalities required to ensure a set of equations of gas flow in pipelines to be hyperbolic.
A.N. Kremlev
Research Institute of Applied Informatics and Mathematical Geophysics, 14 A. Nevskogo ul., Kaliningrad, 236041
Keywords: уравнение эйконала, уравнение Гамильтона-Якоби, лучевой параметр, преломление на выпуклом и вогнутом углах, время первых вступлений, аналитическое вязкое решение, головная волна, конечно-разностная схема Годунова, eikonal equation, Hamilton-Jacobi equation, ray parameter, refraction on convex and concave obtuse angle, first arrival times, analytical viscosity solution, head wave, Godunov finite difference scheme
The strict analytical solution to the eikonal equation for the plane wave refracted on convex and concave obtuse angles has been built. It has a shock line for the ray vector field and the first arrival times at the convex angle and a rarefaction cone with diffracted waves at the concave angle. This cone corresponds to the Keller diffraction cone in the geometric diffraction theory. The comparison of the first arrival times, the Hamilton-Jacoby equation times for downward waves and the conservation ray parameter equation times was made. It is shown that these times are equal only for pre-critical incident angles and are different for sub-critical angles. It is shown that the most energetic wave arrival times, which have dominant practical importance, are equal to the times calculated for the conservation ray parameter equation. The numerical algorithm proposed for these times calculation may be used for arbitrary velocity models.
Z. Lu1,2, L. Li1, L. Cao1, Ch. Hou3 1Chongqing Three Gorges University, Chongqing, 404000, P.R. China 2Tianjin University of Finance and Economics, Tianjin, 300222, P.R. China 3Guangdong University of Finance, Guangzhou, 511300, P.R. China
Keywords: априорные оценки ошибки, нелинейная задача оптимального управления, метод конечных объемов, вариационная дискретизация, a priori error estimates, nonlinear optimal control problem, finite volume method, variational discretization
In this paper, we study a priori error estimates for a finite volume element approximation of a nonlinear optimal control problem. The schemes use discretizations base on a finite volume method. For the variational inequality, we use a method of the variational discretization concept to obtain the control. Under some reasonable assumptions, we obtain some optimal order error estimates. The approximate order for the state, costate, and control variables is Oh2) or O(h2√|lnh|) in the sense of L2-norm or L∞-norm. A numerical experiment is presented to test the theoretical results. Finally, we give some conclusions and future works.
This paper presents an algorithm for solving boundary value problems of the elasticity theory, suitable to solve contact problems and those whose scope of deformation contains thin layers of a medium. The solution is represented as a linear combination of subsidiary solutions and fundamental solutions to the Lame equations. Singular points of fundamental solutions of the Lame equations are located as an external layer of the deformation around the perimeter. Coefficients of the linear combination are determined by minimizing deviations of a linear combination from the boundary conditions. To minimize deviations, the conjugate gradient method is applied. Examples of calculations for mixed boundary conditions are presented.
In the polar coordinates, a discrete analog of the conjugate-operator model of the heat conduction problem preserves the structure of the original model. The difference scheme converges with the second order of accuracy for the cases of discontinuous parameters of the medium in the Fourier law and irregular grids. An efficient algorithm for solving the discrete conjugate-operator model in the case when the thermal conductivity tensor is a single operator.
I.A. Shalimova, K.K. Sabelfeld
Institute of Computational Mathematics and Mathematical Geophysics SB RAS, pr. Acad. Lavrentieva 6, Novosibirsk, 630090, Russia
Keywords: полиномиальный хаос, метод стохастических коллокаций, стационарное уравнение Дарси, метод Монте-Карло, разложение Кархунена-Лоэва, polynomial chaos, probabilistic collocation method, Darcy equation, Monte Carlo method, Karhunen-Loeve expansion
This paper deals with the solution of a boundary value problem for the Darcy equation with a random hydraulic conductivity field. We use an approach based on the polynomial chaos expansion in the probability space of input data. We use the probabilistic collocation method to calculate the coefficients of the polynomial chaos expansion. A computational complexity of this algorithm is defined by the order of a polynomial chaos expansion and the number of terms in the Karhunen-Loève expansion. We calculate different Eulerian and Lagrangian statistical characteristics of the flow by the Monte Carlo and probabilistic collocation methods. Our calculations show a significant advantage of the probabilistic collocation method in comparison with the conventional direct Monte Carlo algorithm.
Based on a collocation technique, we introduce a unifying approach for deriving a family of multi-point numerical integrators with trigonometric coefficients for the numerical solution of periodic initial value problems. A practical 3-point numerical integrator is presented, whose coefficients are generalizations of classical linear multistep methods such that the coefficients are functions of an estimate of the angular frequency ω . The collocation technique yields a continuous method, from which the main and complementary methods are recovered and expressed as a block matrix finite difference formula which integrates a second order differential equation over non-overlapping intervals without predictors. Some properties of the numerical integrator are investigated and presented. Numerical examples are given to illustrate the accuracy of the method.
H. Abdollahi1, S. Shahraki1, and M. Motahari-Nezhad2 1University of Zabol, Zabol, Iran 2Iran University of Science and Technology, Tehran, Iran
E-mail: saeid.shahraki@uoz.ac.ir
Keywords: contact heat transfer, thermal contact conductance, experimental setup, numerical solution
Pages: 499–512
In this paper, a
complete literature review for thermal contact between fixed and periodic
contacting surfaces and also thermal contact between exhaust valve and its seat
in internal combustion engines is presented. Furthermore, the effects of some parameters
such as contact pressure, contact frequency, the contacting surfaces topography
and roughness, curvature radius of surfaces, loading–unloading cycles, gas gap
conductance and properties, interface interstitial material properties,
surfaces coatings and surfaces temperature on thermal contact conductance are
investigated according to the papers presented in this field. The reviewed
papers and studies included theoretical/analytical/experimental and numerical
studies on thermal contact conductance. In studying the thermal contact between
exhaust valve and its seat, most of the experimental studies include two axial
rods as the exhaust valve, and seat and the one ends of both rods are
considered at constant and different temperatures. In the experimental methods,
the temperatures of multi-points on rods are measured in different conditions,
and thermal contact conductance is estimated using them.
A new fundamental
low-parametric equation of state in the form of reduced Helmholtz function for
describing thermodynamic properties of normal substances was obtained using the
methods and approaches developed earlier by the authors. It allows us to
describe the thermal properties of gas, liquid, and fluid in the range from the
density in ideal-gas state to the density at a triple point (except the
critical region) with sufficiently high accuracy close to the ac-curacy of
experiment. The caloric properties and sound velocity of argon, nitrogen, and
carbon dioxide are calculated without involving any caloric data, except the
ideal gas enthalpy. The obtained values of isochoric heat capacity, sound
velocity, and other thermodynamic properties are in good agreement with
experimental (reliable tabular) data.
A semi-empirical model based on
the linear kinetic theory was developed for intense evaporation. The
extrapolated drops for pressure and temperature at the condensed phase surface
were calculated through summing of linear and squared terms. The analytical
dependencies were obtained for gas parameters in gas-dynamic zone as functions
of Mach number, condensation coefficient, and the number of degrees of freedom
for molecules of ideal gas. The calculations from semi-empirical model are in
agreement with results from known analytical and numerical studies.
Results of experimental
studies on dynamics of explosive boiling and third heat transfer crisis under
the conditions of liquid subcooling are presented for the vertical
arrangement of the heat-transfer surface. Acetone was used in experiments at
the pressure in the working volume from 20 to 46 kPa and subcooling from 0 to
20 K. The studied processes were recorded. Data on the velocity of
evaporation front propagation at liquid subcooling were obtained. These data
are compared with the results of calculations according to the models available
in the literature. The effect of liquid subcooling on the regions of regime
parameters corresponding to explosive boiling and third heat transfer crisis is
studied.
The efficiency of a pair
of wind turbines is experimentally investigated for the case when the model of
the second rotor is coaxially located in the wake of the first one. This
configuration implies the maximum level of losses in wind farms, as in the
rotor wakes, the deceleration of the freestream is maximum. As a result of
strain gauge measurements, the dependences of dimensionless power
characteristics of both rotors on the distances between them were determined
for different modes at different tip speed ratios. The obtained results are of interest
for further development of aerodynamics of wind turbines, for optimizing the
work of existing wind farms and reducing their power losses due to interactions
with wakes of other wind turbines during design and calculation.
The
paper presents the numerical simulation results of the surface roughness influence
on gas-dynamic processes inside flow parts of
a supersonic ejector. These simulations are performed using two commercial CFD
solvers (Star-CCM+ and Fluent). The results are compared to each other and
verified by a full-scale experiment in terms of global flow parameters (the
entrainment ratio: the ratio between secondary to primary mass flow rate - ER
hereafter) and local flow parameters distribution (the static pressure distribution
along the mixing chamber and diffuser walls). A detailed comparative study of
the employed methods and approaches in both CFD packages is carried out in
order to estimate the roughness effect on the logarithmic law velocity
distribution inside the boundary layer. Influence of the surface roughness is
compared with the influence of the backpressure (static pressure at the ejector
outlet). It has been found out that
increasing either the ejector backpressure or the surface roughness height, the
shock position displaces upstream. Moreover, the numerical simulation results
of an ejector with rough walls in the both CFD solvers are well quantitatively
agreed with each other in terms of the mean ER and well qualitatively agree in
terms of the local flow parameters distribution. It is found out that in the
case of exceeding the “critical roughness height” for the given boundary
conditions and ejector’s geometry, the ejector switches to the “off-design”
mode and its performance decreases considerably.
In the present paper, we
analyze emergency situations typical of short-duration wind tunnels with
electric-arc or combined test-gas heating in the presence of stabilization and
diaphragm-rupturing systems, which occur in the case of no discharge initiation
in the settling chamber, with the capacitor battery having remained charged during
the start of wind-tunnel systems. For avoiding such emergency situations, some
additional changes based on using feedback elements are introduced into the
wind-tunnel design: the piston of the fast-response valve is made hollow for
increasing the volume of the shutoff cavity and for making the release of
pressure from this cavity unnecessary; the high-pressure channel, which
connects the piston and the piston rod with the settling-chamber cavity, is
filled with a liquid and is closed from the side of the settling chamber with a
piston; the device for controlled diaphragm breakdown is provided with an
external electric circuit intended to control the diaphragm-rupturing process.
Those modifications allow subsequent functioning of the wind-tunnel systems
only in the presence of heat-supply-induced pressure growth in the settling
chamber of the wind tunnel.
The paper presents
results on heat transfer from a cylinder in pulsating flow. The results are
local heat transfer distributions that match four different flow modes identified
previously by the authors. A new kind of dimensionless number was introduced
for pulsating flows: this is a ratio of flow acceleration during unsteady
movement to the centrifugal acceleration due to streamlines bending over the
cylinder. The experimental data were generalized as a dependency of the average
heat transfer on the new dimensionless criterion. The generalization offered a
correction factor to a traditional relation for heat transfer between a
cylinder and air flow past the cylinder; this correction takes into account the
effect of parameters of forced flow pulsations on the average heat transfer.
The results of numerical computations of a free laminar convection and heat transfer between two parallel isothermal plates in the presence of a single rib on the channel surface are presented. The investigations have been conducted for a channel with the aspect ratio AR = L/w = 10, where L is the channel height, and w is the distance between the plates. An infinitely thin adiabatic rib was located on one of the channel walls in the middle of its height. The relative rib height l/w was varied in the range 0¸0.8. The wall temperature was higher than the ambient temperature, and the Rayleigh number was varied in the range Ra = 102¸105. The main attention has been
paid to the study of the influence of the rib height and the Rayleigh number on
local and integral heat transfer and the Reynolds number in the channel (the
convective thrust). A fundamental difference in the heat transfer over the
channel height has been shown on the ribbed wall and on a smooth surface. The
computational results have been compared with the case of a symmetric distribution
of the ribs on the both walls with the integral height equal to a single rib.
The paper presents the results of experimental study for hydrodynamic processes occurring during combustion of a stoichiometric mixture propane-oxygen in combustion chambers with different configurations and submerged into water. The pulses of force acting upon a thrust wall were measured for different geometries: cylindrical, conic, hemi-spherical, including the case of gas combustion near a flat thrust wall. After a single charge of stoichiometric mixture propane-oxygen is burnt near the thrust wall, the process of cyclic generation of force pulses develops. The first pulse is generated due to pressure growth during gas combustion, and the following pulses are the result of hydrodynamic pulsations of the gaseous cavity. Experiments demonstrated that efficient generation of thrust occurs if all bubble pulsations are used during combustion of a single gas combustion. In the series of experiments, the specific impulse on the thrust wall was in the range 104-105 s (105-106 m/s) with account for positive and negative components of impulse.
Characteristics of
gas-phase ignition of grinded brown coal (brand 2B, Shive-Ovoos deposit in
Mongolia) layer by single and several metal particles heated to a high
temperature (above 1000 K) have been investigated numerically. The developed
mathematical model of the process takes into account the heating and thermal decomposition
of coal at the expense of the heat supplied from local heat sources, release of
volatiles, formation and heating of gas mixture and its ignition. The
conditions of the joint effect of several hot particles on the main
characteristic of the process – ignition delay
time are determined. The relation of the ignition zone position in the vicinity
of local heat sources and the intensity of combustible gas mixture warming has
been elucidated. It has been found that when the distance between neighboring
particles exceeds 1.5 hot particle size, an analysis of characteristics and
regularities of coal ignition by several local heat sources can be carried out within the framework of the model of
“single metal particle / grinded coal / air”. Besides, it has been shown with
the use of this model that the increase in the hot particle height leads, along
with the ignition delay time reduction, to a reduction of the source initial
temperatures required for solid fuel ignition. At an imperfect thermal
contact at the interface hot particle / grinded coal due to the natural porosity
of the solid fuel structure, the intensity of ignition reduces due to a less
significant effect of radiation in the area of pores on the heat transfer
conditions compared to heat transfer by conduction in the near-surface coal
layer without regard to its heterogeneous structure.
Kinetic calculations
of the plasma processing/utilization process of organic waste in air and steam
ambient were carried out. It is shown that, during the time of waste residence
in the plasma reactor, 0.7 and 1.2 s, at the exit from the reactor there
forms a high-calorific fuel gas with a combustion heat of 3540 and
5070 kcal/kg, respectively. In this process, 1 kg of waste yields 1.16 kg of fuel gas at air
gasification of waste and 0.87
kg of pure synthesis gas at steam gasification. The energy efficiency of the waste gasification
process, defined by the ratio between the calorific value of the resultant fuel
gas and the initial calorific value of the waste amounts to 91 % in
air plasma and 98 % in steam plasma. A comparison between the results of
kinetic and thermodynamic calculations has revealed their good agreement.
Thermodynamic analysis of
plasma gasification of various renewable carbon-bearing materials was carried
out using various oxygen-containing oxidants (oxygen, air, water). The
possibility of obtaining calorific synthesis gas suitable for the needs of heat
power engineering was confirmed.
Structure of ceramics obtained by the plasma spray deposition of spherical TiO2
powders has been investigated. An electron microscopy study of the surfaces and cross sections of particles in the initial powder and of the deposited ceramic coatings was performed. X-ray diffraction and Raman scattering data proved that the coatings were mainly structured as rutile. In addition, Raman and X-ray diffraction data have revealed an amorphous phase, an anatase phase, and non-stoichiometric phases Ti8O15, Ti10O19, Ti7O13, etc.
being present in the coatings. The observed suppression of (011) and (111) XRD peaks and an
increased intensity of (110) peak are indicative of a predominant orientation
of grains in the synthesized ceramics. Mechanisms of formation of the complex
coating structure are discussed.
In the present paper, we report on experimental and simulated data on the impact of cellular-porous-material heating on the wave drag of a cylinder with a frontal gas-permeable porous insert streamlined by a supersonic flow (М∞ = 4.85, Re1∞ = 3.3×106
m-1). Weighing data obtained in the supersonic wind tunnel are
compared with data simulated using a discrete model of the cellular-porous
material. An increase of the wave drag with a growth of porous-insert
temperature and its decrease occurring upon decreasing the temperature are
demonstrated.
The
technology of electricity production by a mini-thermal power plant, operating
on combined cycles of Otto and Rankine, is considered. The main aspects of the
investigation methodology are outlined. It is shown that the design and layout
parameters of all the major energy elements of the developed technology allow
implementing it in a block and modular version; and the efficiency of
electricity supply for the proposed technology will be at least 50 %.
Yu. Yu. Bozhko, O. S. Subbotin, K. V. Gets, R. K. Zhdanov, V. R. Belosludov
Nikolaev Institute of Inorganic Chemistry, Siberian Branch, Russian Academy of Sciences, Novosibirsk, Russia
Keywords: решеточная динамика, термодинамические свойства, фазовые равновесия, двойные клатратные гидраты, закись азота, ксенон, lattice dynamics, thermodynamic properties, phase equilibria, double clathrate hydrates, nitrous oxide, xenon
Structural, dynamic, and thermodynamic features of double hydrates of xenon and nitrous oxide are calculated. Thermodynamic stability regions of these hydrates are found. At the atmospheric pressure the xenon hydrate is in the equilibrium with the gas phase at temperatures up to 263 K, whereas at these pressures the nitrous oxide hydrate decomposes already at 218 K. A strong dependence of the equilibrium temperatures and pressures of the formation/decomposition of double nitrous oxide and xenon hydrates on the composition of their mixture in the gas phase is shown.
M. R. Ryzhikov1,2, S. G. Kozlova1,2 1Nikolaev Institute of Inorganic Chemistry, Siberian Branch, Russian Academy of Sciences, Novosibirsk, Russia 2Novosibirsk National Research State University, Novosibirsk, Russia
Keywords: кластерные трехъядерные соединения железа, индуцируемые токи, химические сдвиги ЯМР Н, теория функционала плотности, trinuclear iron cluster compounds, induced currents, Н NMR chemical shifts
, density functional theory
The quantum chemical calculations of induced electric currents in (μ-H)2Fe3(μ3-Q)(CO)9 complexes, where Q = S, Se, Te, are carried out. It is demonstrated that the appearance of anomalous 1Н NMR chemical shifts on bridging hydrogen atoms is, first of all, due to the effect of induced currents on iron atoms.
L. N. Mazalov1,2, S. A. Lavrukhina1, A. D. Fedorenko1, G. I. Semushkina1, A. V. Kalinkin3 1Nikolaev Institute of Inorganic Chemistry, Siberian Branch, Russian Academy of Sciences, Novosibirsk, Russia 2Novosibirsk National Research State University, Novosibirsk, Russia 3Boreskov Institute of Catalysis, Siberian Branch, Russian Academy of Sciences, Novosibirsk, Russia
Keywords: рентгеновская эмиссионная спектроскопия, рентгеновская фотоэлектронная спектроскопия, квантово-химические расчеты, метод DFT, каликс[4]аренфосфиноксиды, тиакаликс[4]аренфосфиноксиды, экстрагент, X-ray emission spectroscopy, X-ray photoelectron spectroscopy, quantum chemical calculations, DFT method, calix[4]arene phosphine oxides, thiacalix[4]arene phosphine oxides, extractant
The electronic structure of calix[4]arene phosphine oxides (CPO) and thiacalix[4]arene phosphine oxides (TCPO) is studied by X-ray photoelectron and emission spectroscopy and quantum chemical methods. The electron density distribution over atoms contained in CPO and ТCPO is analyzed. The structure of higher occupied molecular orbitals (HOMO) is examined. It is shown that HOMOs of these compounds mainly consist of contributions of oxygen 2 p atomic orbitals (AOs) of phosphoryl and hydroxyl moieties and also bridging sulfur 3 p АОs, which indicates the bifunctionality of the considered extractant molecules. The mutual effect of the lower and upper rims of CPOs and ТCPOs as well as the effect of their structures on the electron density distribution over calixarene molecules is investigated
Yu. V. Fedoseeva1,2, T. A. Duda3, A. G. Kurenya1, A. V. Gusel'nikov1, K. S. Zhuravlev3, O. Yu. Vilkov4, L. G. Bulusheva1,2, A. V. Okotrub1,2 1Nikolaev Institute of Inorganic Chemistry, Siberian Branch, Russian Academy of Sciences, Novosibirsk, Russia 2Novosibirsk National State Research University, Novosibirsk, Russia 3Rzhanov Institute of Semiconductor Physics, Siberian Branch, Russian Academy of Sciences, Novosibirsk, Russia 4St. Petersburg State University, Sankt-Peterburg, Russia
Keywords: наночастицы CdS, углеродные нанотрубки, рентгеновская фотоэлектронная спектроскопия, рентгеновская спектроскопия поглощения, электронное строение, CdS nanoparticles, carbon nanotubes, X-ray photoelectron spectroscopy, X-ray absorption spectroscopy, electronic structure
The composition and electronic structure of cadmium sulfide (CdS) nanoparticles formed by the Langmuir-Blodgett (LB) technique on clean silicon wafers and the surface of vertically aligned carbon nanotube (CNT) arrays are studied by X-ray photoelectron spectroscopy (XPS) and near-edge X-ray absorption fine structure (NEXAFS) spectroscopy. The samples were annealed in a vacuum at 175 °C and 225 °C to remove the organic matrix of the LB film. From the analysis of the XPS data the increased concentration of sulfate groups on the surface of CdS nanoparticles formed on CNTs and the electron density transfer from CdS to CNTs are determined. An increase in the LB film annealing temperature causes an increase in the degree of crystallinity and the CdS crystallite size and a decrease in the photoluminescence intensity of a CdS-CNT hybrid.
A. A. Ryadun, V. A. Nadolinny, O. V. Antonova, M. I. Rakhmanova
Nikolaev Institute of Inorganic Chemistry, Siberian Branch, Russian Academy of Sciences, Novosibirsk, Russia
Keywords: люминесценция, ЭПР спектроскопия, кристаллы трибората лития, катионные вакансии, luminescence, EPR spectroscopy, lithium triborate crystals, cation vacancies
An attempt is made to explain the causes of coloration of LiB3O5 crystals after their long-term operation as laser elements. By EPR and optical spectroscopy the impurity and radiation centers are studied in as-grown LiB3O5 crystals and in the crystals whose color appeared after the long-term operation as laser elements. In a number of as-grown crystals a copper impurity is detected. EPR spectral parameters and the structural positions of Cu2+ ions are found. Defect formation features in electron irradiated as-grown LiB3O5 crystals and in the most colored regions of crystals of spent laser elements are analyzed. It is shown that in both growth crystals and crystals after long-term operation as laser elements the same set of radiation defects is observed: oxygen О- in the interstitial position, an О- hole center in the crystal structure, and the В2+ electron center due to the removal of an oxygen atom near the lithium vacancy. The only distinction is that the concentration of these radiation defects in crystals long used as laser elements is higher than that in growth ones by an order of magnitude. The results obtained enable the conclusion that the cause of coloration of LiB3O5 crystals is photo-induced diffusion of lithium atoms and their capture by cation vacancies in the dark part of the crystal, which provides the formation and accumulation of lithium vacancies in the region where the laser beam passes.
A. I. Romanenko1,2, G. E. Yakovleva1, V. E. Fedorov1,3, A. Yu. Ledneva1, V. A. Kuznetsov1, A. V. Sotnikov1, A. R. Tsygankova1,3, B. M. Kuchumov1 1Nikolaev Institute of Inorganic Chemistry, Siberian Branch, Russian Academy of Sciences, Novosibirsk, Russia 2Tomsk National Research State University, Tomsk, Russia 3Novosibirsk National Research State University, Novosibirsk, Russia
Keywords: слоистые халькогениды переходных металлов, электропроводность, термоэдс, layered transition metal chalcogenides, electrical conductivity, Seebeck coefficient
Temperature dependences of the electrical conductivity are studied in the range 4.2-300 K and Seebeck coefficient at room temperature of bulk samples of tungsten dichalcogenide polycrystals with niobium substitutions for tungsten and selenium substitutions for sulfur - W1- x Nb x (S1- y Se y )2. The two-dimensionalization of electron transport properties is detected at niobium concentrations x ³ 0.1 in W1- x Nb x S2 and x ³ 0.05 in W1- x Nb x Se2. In samples with additional partial selenium substitution for sulfur the electron transport remains three-dimensional. At room temperature the Seebeck coefficient (at equal electrical conductivities) is several times higher in the samples with quasi-two- dimensional transport than in the samples with three-dimensional transport. The calculation of the power factor at room temperature shows its nine times increase.
T. I. Asanova1, I. P. Asanov1,2, M.-G. Kim3, S. V. Korenev1,2 1Nikolaev Institute of Inorganic Chemistry Siberian Branch, Russian Academy of Science, Novosibirsk ,Russia 2Novosibirsk National Research University, Novosibirsk ,Russia 3Pohang University of Science and Technology, Pohang, Republic of Korea
Keywords: наносплав PtOs, биметаллические наночастицы, [Pt(NH)][OsCl], механизм термического разложения, XAFS, РФЭС, размерный эффект, PtOs nanoalloy, bimetallic nanoparticles, mechanism of thermal decomposition, XPS, size effect
In the paper results of the investigation of the thermal decomposition process of double complex salt [Pt(NH3)4][OsCl6] by x-ray absorption (XAFS) and photoelectron (XPS) spectroscopies have been presented. The data obtained allows a mechanism of the thermal decomposition to be refined. An influence of size effect and nanoalloy formation on chemical shift of Pt and Os is discussed.
Yu. A. Galkina1,2, N. A. Kryuchkova1, M. A. Vershinin1, B. A. Kolesov1,2 1Nikolaev Institute of Inorganic Chemistry, Siberian Branch, Russian Academy of Sciences, Novosibirsk, Russia 2Novosibirsk National Research State University, Novosibirsk, Russia
Keywords: спектры КР, сильные водородные связи, квантово-химический расчет, изотопозамещение, Raman spectra, strong hydrogen bonds, quantum chemical calculation, isotopic substitution
The work deals with the establishment of the dependence of the vibrational frequencies of strong O-H…O and N-H…O hydrogen bonds for the diagnosing the bonds themselves. To this end, the Raman spectra of a large number of different normal and deutero-substituted crystals characterized by the presence of strong O-H…O and N-H…O bonds are measured and the quantum chemical calculation is performed for one of these compounds. The dependence of the O-H stretching frequency on the O…O distance is constructed differing from that previously known for short O…O contacts. The mechanisms of significant broadening of the O-H vibration band in strong O-H…O hydrogen bonds are considered. Different dependences of the N-H vibrational frequencies in N-H…O bonds are reported and the causes of this diversity are discussed.
O. G. Shakirova1, L. G. Lavrenova2,3, N. V. Kuratieva2,3, A. S. Bogomyakov3,4, L. A. Sheludyakova2,3, A. P. Mosalkova5, Yu. V. Grigoriev5 1Komsomolsk-on-Amur State Technical University, Komsomolsk-on-Amur, Russia 2Nikolaev Institute of Inorganic Chemistry, Siberian Branch, Russian Academy of Sciences, Novosibirsk, Russia 3Novosibirsk National Research State University, Novosibirsk, Russia 4International Tomography Center, Siberian Branch, Russian Academy of Sciences, Novosibirsk, Russia 5Belarusian State University, Minsk, Belarus
Keywords: синтез, координационные соединения, железо(II), 2-(2-трет-бутилтетразол-5-ил)пиридин, структура, магнитные свойства, synthesis, coordination compounds, iron(II), 2-(2-tert-butyltetrazol-5-yl)pyridine, structure, magnetic properties
Iron(II) dicyanamide and isothiocyanate compounds with 2-(2- tert -butyltetrazol-5-yl)pyridine (L) of the composition [FeL2(C2N3)2]×2H2O (I) and [FeL2(NCS)2]H2O (II) are synthesized and studied. The compounds are examined using powder and single crystal XRD (for I), electron (diffuse reflectance spectra) and IR spectroscopy, static magnetic susceptibility. The analysis of the dependence meff( Т ) indicates that the exchange interactions of antiferromagnetic nature appear between the iron(II) ions at temperatures below 50 K.
a:2:{s:4:"TYPE";s:4:"HTML";s:4:"TEXT";s:110:"S. P. Gabuda†1, S. G. Kozlova1,2, N. B. Kompankov1, K. S. Redkina2";} 1Nikolaev Institute of Inorganic Chemistry, Siberian Branch, Russian Academy of Sciences, Novosibirsk, Russia 2Novosibirsk National Research State University, Novosibirsk, Russia
Keywords: водный раствор триэтиламина, фазовый переход, ЯМР Н, aqueous triethylamine solution, phase transition, Н NMR
The 1Н NMR spectra in a binary aqueous triethylamine solution are recorded with a lower critical point of the liquid-liquid phase transition. It is found that, above the critical temperature the 1Н NMR spectra of water and triethylamine molecules in the phase with a predominant content of triethylamine molecules are characterized by an inhomogeneous broadening. It can be supposed that the found broadening is due to the features of the molecular distribution at the interface.
N. V. Podberezskaya1, V. Yu. Komarov1,2, M. Yu. Kameneva1, L. P. Kozeeva1, A. N. Lavrov1 1Nikolaev Institute of Inorganic Chemistry, Siberian Branch, Russian Academy of Sciences, Novosibirsk, Russia 2Novosibirsk National Research State University, Novosibirsk, Russia
Keywords: кобальтаты, монокристаллы, нестехиометрия по кислороду, структурный анализ, обработка рентгендифракционных данных, структурные модели, cobaltates, single crystals, oxygen non-stoichiometry, structural analysis, X-ray diffraction data processing, structural models
Impurity-free R BaCo4O7+ x ( R = Y, Lu) crystals are grown and the evolution of their structure with varying oxygen concentration in the range 0 £ x £ 1.3 is studied. The structural features of the studied samples required to develop an extended strategy of the X-ray crystallographic experiment, which made it possible to obtain more accurate data on unit cell parameters and additional information on the features of superstructure modulation and diffuse scattering, along with the phase composition of crystalline samples. A crystal chemical analysis of the known structural models of R BaCo4O7+ x is performed and suggestions are made about possible structural changes occurring when the oxygen concentration increases up to the limit.
S. V. Borisov, N. V. Pervukhina, S. A. Magarill
Nikolaev Institute of Inorganic Chemistry, Siberian Branch, Russian Academy of Sciences, Novosibirsk, Russia
Keywords: кристаллографический анализ, катионные подрешетки, механико-волновая концепция кристаллического состояния, когерентная сборка, механизм кристаллизации, crystallographic analysis, cation sublattices, mechanical-wave concept of crystal state, coherent assembly, crystallization mechanism
By means of the mechanical-wave concept of crystal state and the crystallographic analysis the universal regularities of the crystal structure formation are determined: presudotranslational ordering of atoms within unit cells; separate ordering of different groups of atoms with the alignment of their sublattice parameters; the principle of coherent assembly a structure from stable building blocks with the local geometry and block symmetry spread on the structure formed, and so on. The crystallization mechanism is illustrated by specific structures.
V. V. Bakakin
Nikolaev Institute of Inorganic Chemistry, Siberian Branch, Russian Academy of Sciences, Novosibirsk, Russia
Keywords: катионные каркасы, темплаты, ортобораты, фторидобораты бария, фторидобораты свинца, антицеолиты, cation frameworks, templates, orthoborates, barium fluoride borates, lead fluoride borates, antizeolites
The crystallogenesis of three groups of structures of fluoride-orthoborates (and their analogs) with large cations is studied from the point of view of the current cation-framework representations. Their cation frameworks are sterically templated by rigid borate anions and are built as antizeolite structures. Cavities of channel or layered types are filled with components different their composition and configuration with the main function as charge compensators. An example of different functionalities of the identical anions are Ba3(BO3)2 and La3Ca3(BO3)5 structures. In these structures, two (BO3) types generate a cation framework, and the third type stabilizes it in ready channels (!).
A. S. Sukhikh1,2, T. V. Basova1,2, S. A. Gromilov1,2 1Nikolaev Institute of Inorganic Chemistry, Siberian Branch, Russian Academy of Sciences, Novosibirsk, Russia 2Novosibirsk National Research State University
Keywords: рентгеновская дифрактометрия поликристаллов, ориентированные образцы, тонкие пленки, индицирование, фталоцианины палладия, X-ray diffractometry of polycrystals, oriented samples, thin films, indexing, palladium phthalocyanines
An approach for the substantiated choice of the indexing procedure of a diffraction pattern is described. The technique is based on a combined use of powder X-ray diffraction data in Bragg-Brentano schemes and 2D GIXD of mainly oriented polycrystalline samples.
