Search

The article reveals a brief history of bioethics and the relevance of the subject of biomedical ethics in a medical university for the formation of professional and moral qualities of a future doctor. The main content of this discipline in domestic and foreign education is revealed. Topical issues of the theory and methodology of teaching bioethics in a medical university are described, including the ones based on the author’s pedagogical experience. The main problems in teaching biomedical ethics at the beginning of the XXI century are noted.

Subject. The article considers the corporate governance implementation in Russia under modern conditions and evaluates its efficiency. Objectives. The aim is to identify key areas for strengthening and developing the corporate governance practices in Russian companies that will enable to improve the existing corporate governance model. Methods. The study draws on comparative analysis, ranking, classification, formation of ratings on the basis of sociological surveys. Results. The paper includes recommendations on creating a single standard to assess corporate government practices, which should involve three parties, i.e. the business, rating agencies and the State, and consider their interests. I offer a methodology for overall assessment of components investigated by rating agencies that may help investors understand the business activity of companies. Conclusions. Public companies and State-owned corporations demonstrate the best results in the sphere of corporate governance. It is critical to enhance corporate governance in Russia, which implies developing the corporate legislation, improving the law enforcement practice. Companies should be willing to take measures to perfect corporate governance.

To cut the amount of machine time spent on designing systems with electric machines and semiconductor converters, it is proposed to describe processes using smooth current and voltage constituents. It is also proposed to use dual system models that combine the simulation using smooth components of curves with the simulation of systems by interconnected subsystems. This allows reconciling the requirements on the speed and accuracy of calculating long-time processes. An example of creating a dual solid-state drive model with a PMAC motor is provided.

Statistical analysis of the results of molecular dynamics (MD) calculation of gas-phase “self-assembling” of nanoclusters during metal vapor condensation revealed the laws of energy transfer between metallic clusters and inert gas atoms. A model is proposed to determine the parameters of heat exchange between clusters and the environment at the initial stage of condensation. This model is based on averaged MD data on the interaction between small clusters and argon atoms. The parameters that can be used to transfer information from MD to a macroscopic condensation model are numerically determined. The results obtained can be used to describe nucleation to predict a nanoparticle size distribution in the production of metallic powders.

The latest changes in the algorithms for the formation of the International Atomic Time (TAI) scale are reported in terms of estimating the weights of the clocks involved in the formation of TAI. The characteristics of the long-term instability of new-generation hydrogen frequency and time standards from the State Primary Standard of time and frequency units and national time scale, GET 1-2018, were studied. The study was based on the results of processing the frequency difference with respect to TAI. It is confirmed that presently, new-generation hydrogen standards of frequency and time show significantly less long-term instability compared with similar and other quantum frequency standards.

The structures of systems with high-voltage cascade frequency converters containing multi-winding transformers and low-voltage low-power converters connected in series at each output phase of the load are considered. Low-voltage blocks contain three-phase diode or active rectifiers, DC capacitor filters, single-phase stand-alone voltage inverters and block disconnecting devices in partial modes (in case of failure when part of the blocks are disconnected). The possibilities of operation of cascade converters are determined, equations for correcting tasks to units in partial modes are given, tables of correction of tasks with estimates of achievable load characteristics are proposed. The results of experiments on the model of a powerful installation with a cascade frequency converter are presented, confirming the possibility of ensuring the symmetry of the load currents when disconnecting part of the blocks and the asymmetry of the circuit.

The results of the molecular-dynamic calculations of gas-phase nanocluster “self-assembly” during metal vapor condensation have been statistically analyzed parting terms of a computational scheme suitable for describing condensation. The laws of collisions and the growth of small copper clusters are revealed. The parameters that describe the interaction between clusters and metal atoms and are used to transfer information to a macroscopic nucleation model are determined. The results can be used for describing nucleation for predicting a nanoparticle size distribution in the production of metal nanopowders.

The latest changes in the algorithm for the formation of the international atomic time scale TAI are reported in terms of estimating the weights of the clocks involved in the formation of TAI. Studies of the characteristics of the long-term instability of new-generation hydrogen masers based on processing the results of the clock frequency difference with respect to TAI are performed. It has been confirmed that at present, new-generation hydrogen masers show significantly less long-term instability in comparison with quantum frequency standards ofsimilar and other types.

A statistical analysis of the results of molecular-dynamic calculations of metal (Cu or Ti) vapor condensation in an inert gas (Ar) medium has been performed. Condensation proceeds with the formation of small particles consisting of metal atoms—clusters. The internal energy of the metal cluster—the sum of the kinetic energy of the atoms in the center of mass system and potential energy—is chosen as the key characteristic describing its state. It is shown that the internal energy value gives the possibility for the prediction of the duration of the cluster existence, from birth to decay, i.e., it describes the ability of the cluster to grow. The temporal evolution of the distribution function of the clusters over the internal energy values is presented.

A molecular dynamics study was carried out on the dependence of the radii of small metal clusters that form in the process of gas-phase copper condensation on the number of atoms in them. The radii are calculated with the molecular-kinetic theory formulas from molecular-dynamic simulating data on the number of collisions between clusters. It was found that the dependence of the radii on the number of particles has a form close to the classical n1/3. However, the average cluster radii are about 40% larger than the case in which the cluster is considered a drop of a bulk fluid.

A computing scheme for a mesoscopic description of a nucleation process has been built using a statistical analysis of the results of molecular dynamics simulation of a supersaturated metallic vapor. The parameters that enter into equations for cluster growth rate and heat release during condensation are found by a direct statistical computation in a molecular dynamics method. The rates of cluster formation calculated by a molecular dynamics method agree well with the numerical model developed in this work.

The author of the article proposes the development and implementation of a professionally oriented approach in higher education into the pedagogy of higher education. The professionally oriented approach provides for such a specialization of the general humanitarian, physical culture and natural science training of students, in which professional guidelines, theoretical and practical knowledge constructs, necessary for a future specialist in the field of activity being mastered, will be laid in the corresponding academic disciplines. A professionally oriented approach, on the one hand, based on general knowledge, gives a number of skills necessary in a future profession, and on the other hand, develops an additional interest in general educational disciplines in students due to the understanding that, in addition to the general outlook and development of the person, they they are also needed in their future profession. In the article, the professionally-oriented approach proposed by the author is considered on the example of physical culture and sports training of future teachers and coaches in physical culture and sports on the basis of pedagogical and physical education universities, which requires an art teacher to link his own academic discipline with the work profile of the university in which the teaching is conducted.

The article presents some of the problems that arise when creating power inverters. The analysis is introduced to the use of self-oscillating amplifiers utilizing for the construction of inverters. The calculation gives for the amplifier with full control of the output voltage. The calculation is confirmed by practical results.

We discuss the problem of dimer formation during the homogeneous nucleation of atomic metal vapor in an inert gas environment. We simulated nucleation with molecular dynamics and carried out the statistical analysis of double- and triple-atomic collisions as the two ways of long-lived diatomic complex formation. Close pair of atoms with lifetime greater than the mean time interval between atom–atom collisions is called a long-lived diatomic complex. We found that double- and triple-atomic collisions gave approximately the same probabilities of long-lived diatomic complex formation, but internal energy of the resulted state was essentially lower in the second case. Some diatomic complexes formed in three-particle collisions are stable enough to be a critical nucleus.

Active and passive hydrogen masers developed and manufactured by Russian company “Vremya-CH” are widely used over the world in scientific laboratories, radio astronomy observatories, national time keeping services and telecommunication systems.

Statistical analysis of the results of molecular-dynamic modeling for nucleation of metal (Cu) vapors in inert gas atmosphere (Ar) is carried out. Features of the initial stage of nucleation are considered for estimation of the probability of the growth of small atomic clusters within a supersaturated nonequilibrium medium and the efficiency of heat removal from them during collisions with inert gas atoms and other metal atoms.

Рассмотрены структуры систем с высоковольтными каскадными преобразователями частоты, содержащими многообмоточные трансформаторы и низковольтные маломощные блоки преобразования, соединенные по выходу последовательно в каждой фазе нагрузки. Низковольтные блоки содержат трехфазные диодные или активные выпрямители, конденсаторные фильтры выпрямленных напряжений, однофазные автономные инверторы напряжения и устройства отключения блоков в частичных режимах (при выходе из строя и отключении части блоков). Определены возможности работы каскадных преобразователей, даны уравнения для корректировки заданий блокам в частичных режимах, предложены таблицы корректировки заданий с оценками достижимых характеристик нагрузки. Приведены результаты экспериментов на макете мощной установки с каскадным преобразователем частоты, подтверждающие возможности обеспечения симметрии токов нагрузки при отключении части блоков и несимметрии схемы.

In this paper mathematical description of three-phase bridge voltage source inverter with considering of snubber circuits and total switching time of transistors is presented. Modeling was performed by methodology of system modeling by inter-connected subsystems. Calculation results, that confirmed advisability of described clarifications of inverter model are presented. Developed mathematical description of inverter is utilized for clarification of models of active front-end, frequency converters and other equipment, included in created complex of models.

The characteristics of a group signal obtained by means of an auxiliary oscillator tuned to the average frequency of the signals of an ensemble of active hydrogen frequency and time standards are analyzed. The data of actual measurements conducted at the Vremya-Ch company in 2013 are used for the analysis.

An algorithm is developed to construct an effective pair potential that can reproduce several characteristics of a system during a molecular dynamics simulation. This algorithm is based on the Schommers method and the Belashchenko method of potential hybridization and is used to construct an effective pair potential for liquid iron near the melting temperature. The constructed potential well reproduces the pair correlation function of liquid iron in an NPT ensemble with zero pressure in a barostat and provides good agreement for the atomic density and the linear thermal expansion coefficient. © 2012 Pleiades Publishing, Ltd.

The features of the start-up of asynchronized synchronous compensators (ASC) are described. The characteristic of the PU-6-05 starters for the ASK-100 compensators produced by “Elektrosila,” branch of the JSC “Silovye macshiny,” is given. Problems of determining the position of the rotor, operations in the artificial and natural switching zones, and the processes of synchronizing the compensator with the power network and slowing of the power plant are considered.

The structure and properties of liquid cesium are calculated over a wide temperature range. The Shommers method, which is based on Winter's experimental data, is used to construct structural models. A density of states is obtained by a recursive method using an LMTO Hamiltonian. Electrical conductivity is calculated by the Kubo-Greenwood formula. The degree of electron localization as a function of temperature is estimated, and the metal-nonmetal transition in cesium is shown to be related to electron localization at atomic clusters. © 2010 Pleiades Publishing, Ltd.

This paper reports on the development of hydrogen quantum standards of frequency and time of a new generation, including the Ch1-90 active laser and the Ch1-91 passive laser. Descriptions are given of the block diagrams and construction, and technical characteristics are quoted together with experimental tests on the frequency instability. Unique metrological characteristics have been obtained for standard hydrogen instability of frequency per 1 day (the mean standard deviation) for the Ch1-90 and Ch1-91 are, respectively, 3·10–16 and 2.5·10–15, which allows one to meet the requirements of the standard state basis for the precision time and frequency.

A stand-alone system with a 6-phase asynchronous generator and several active semiconductor converters is considered. The algorithms of the device operations are developed and a model for calculating the steady-state and transient operating modes is described. The results of the analysis of the system are presented.

The structures of the models of the Lennard-Jones liquid and mercury, cesium, and rubidium melts have been investigated. According to the local order dominant in a system, three regions have been selected in the phase diagrams of the models. For the Lennard-Jones model, the transition between the selected regions corresponds to a change in the asymptotic behavior of the radial distribution function. For the Hg, Cs, and Rb models, the position of the boundaries between these regions correlates with the specific features of the physical properties of these materials. © Allerton Press, Inc. 2008.

UDC 535.52:66.045 Processing of solutions and suspensions that yields a dry end product is a promising application of rotor film-type evaporators (RFEs), which make it possible to replace periodic multistage processes with continuous combined processes. In view of this, it is a very urgent matter to study the heat exchange during deep concentration of solutions and suspensions. As shown by many studies, heat exchange in RFEs is complex and is determined by both the hydrodynamic conditions in the evaporator and the properties of the product being processed, the design features and rotation frequency of the rotor, and the heat flux density, Despite the complexity of the process, numerous attempts have been made to obtain an equation to describe it. In studies [1, 2] on heat exchange in an articulated-rotor RFE during evaporation of toluene, water, ethyl alcohol, and sugar syrup Dieter concluded that the heat-transfer coefficient does not depend on the spraying density and the heat flux density and increases with the rotation frequency of the rotor. The data reported by different authors for articulated-rotor evaporators are very contradictory. In [3] Marchenko obtained a criterial dependence by generalizing experimental data on vaporization of water, but it takes no account of the influence of the rotation frequency of the rotor on the heat-transfer coefficient. In [4] Kibrik established a relation between the heat-transfer coefficient and the design features of the rotor. In a study of convective heating and evaporation of distilled water, glycerin solutions, and solutions of S-150 additive in benzine in an articulated-rotor RFE [5] Golova obtained criterial equations, which in our opinion take insufficient account of the influence of the design features of the rotor, since the only the influence of the number of rotors was considered. Shevchuk [6] investigated how the heat transfer is affected by a large number of factors: the flow rate of the liquid, the physicochemieal properties of the products studied (distilled water, aqueous solutions of glycerin and esters of unsaturated higher fatty acids), the rotation frequency of the rotor, the direction of the specific heat flux (during convective heat exchange), the instantaneous length of the evaporator, and the design features of the rotor. The studies were carried out in glass and metal evaporators. After analyzing the hydrodynamic and heat-exchange laws by using a semi-empirical theory of turbulent transfer, Nikitin and Fedorov [7] obtained computational relations for determining the heat-transfer coefficient in the RFE heating zone during processing of pseudoplastic solutions. In our opinion, they did not take sufficient account of the influence that the rotor design features and the variation of the non-Newtonian liquids have in the process of solvent removal. The first attempt to study heat exchange during concentration of NaCI and NaNO 3 solutions to obtain a dry product in a RFE with rigidly fastened blades was made by Lysenko [8]. The average heat-transfer coefficient was found to increase with the heat flux. It is difficult to agree with that conclusion, when the physics of the process and the relation obtained are considered. The heat exchange in a RFE during concentration of azo dyes (they were obtained in dry form) was studied by Nagieva [9]. Arbitrarily dividing the RFE with a combined rotor (with hinged blades at the top and rigid blades at the bottom) into three zones (a zone of heating and onset of evaporation of the initial product, a zone of intensive evaporation, and a drying zone), she obtained criterial relations for each zone and for each product studied. It should be noted that the rotor design features and the non-Newtonian properties of the suspension in the second zone are not taken into account in those relations.

The condensation of metal vapor in an inert gas is studied by the molecular dynamics method. Two condensation regimes are investigated: with maintenance of partial pressure of the metal vapor and with a fixed number of metal atoms in the system. The main focus is the study of the cluster energy distribution over the degrees of freedom and mechanisms of the establishment of thermal equilibrium. It is shown that the internal temperature of a cluster considerably exceeds the buffer gas temperature and the thermal balance is established for a time considerably exceeding the nucleation time. It is found that, when the metal vapor concentration exceeds 0.1 of the argon concentration, the growth of clusters with the highest possible internal energy occurs, the condensation rate being determined only by the rate of heat removal from clusters. © 2012 Pleiades Publishing, Ltd.

We present results of the analysis of several structural models of metallic and nonmetallic liquids. Models cover the region of expanded liquid phase and supercritical fluid phase. The goal is to show that there are at least two regions on phase diagram, where liquid phase has essentially different atomic structure. Dense liquid and loose liquid have different atomic and electronic properties, as it could be seen from experiments. © Owned by the authors, published by EDP Sciences, 2011. Coherent Inc.;Crisel Instruments srl;Dipartimento di Fisica of the University of Roma "La Sapienza";ELETTRA Synchrotron Radiation Facility;ENEA;Sparx

A brief analysis is given of the works on the hydrodynamics of a flowing film. The basic model representations of a flow are considered. Possibilities of using statistical-mean wave characteristics of a film flow for further development and refinements of semiempirical theories of transfer in flowing films and design procedures for film technological apparatuses and power cooling systems are pointed out.

A modification of the LMTO method was used for the investigation of the electronic structure of melts in the wide temperature and density range. Modelling consisted of two steps: self-consistent calculation for a supercell (approximately 50 atoms) by LMTO method, and calculation of electronic structure and properties of a large system (approximately 4000 atoms) by recursion method with LMTO basis functions. This method was tested on Fe, Cs and Hg melts. Our results are in agreement with the ab-initio calculation results for temperatures near the melting point. Features of metal-nonmetal transition for Hg and Cs at high temperatures were obtained. © 2008 IOP Publishing Ltd.

The atomic structures of liquid rubidium were simulated by classical and first-principle Molecular Dynamics methods for a range of temperatures. The pair potentials necessary for the Classical Molecular Dynamics calculations were obtained using diffraction data by the Schommers iterative method. In all cases simulated pair correlation functions and structure factors correctly reproduced the experimental ones. A Delaunay simplex, comprised by four atoms, is the simplest element of the structure. All atomic aggregates in an atomic structure consist of them. The structure factor of the simplicial voids system is additional structural characteristic which allows seeing distinction in structures with almost similar pair correlation functions. © 2008 IOP Publishing Ltd.

ized within a few seconds at 373-413 K. In our investigation of the kinetics of the inter- action of HCO fatty acid glycerides with an aqueous caustic solution (chemically pure grade), we performed experiments at temperatures of 373, 383, 383, 403, and 413 K. HCO concentrations of 0.047, 0.093, and 0.141M in the reaction mixture were selected on the basis of normal practice in the production of soap/oil concentrates. The sapon- ification was performed in a mixture of MS-20 and 1-50A oils (7:3 by weight). In each ex- periment, an aqueous solution of lithium hydroxide (10.45%) was introduced into the reaction mixture in an amount 10% over the stoichiometric requirement for complete saponification of the HCO. In the course of saponification, samples were taken at identical intervals of time and analyzed by potentiometric titration. The experimental data were approximated on the basis of an area method (5), with a 3.5% error, by the exponential relationship

A method of graphic analysis is considered for the calculation of the local thickness of a liquid film in the entrance section of the transformation of slot flow into film flow over a vertical plate. The proposed method can also be used in calculating the local thicknesses of a thin layer during liquid flow over curved surfaces.

The velocity field in the initial section of gravitational film flows has been investigated analytically and experimentally, and a relationship has been obtained for calculating the length of this section.

A simplified solution for the thermal entry zone in the stabilization of a film is confirmed by experiments at Re ≤450 for boundary conditions of the first type.

It is shown experimentally as well as analytically that the gravitational flow of nonuniformly distributed thin liquid layers along the external surface of a vertical tube is a nonsteady film flow which later goes over into a jet flow.

The maximum, wave amplitudes are analyzed for a change in the spray density and in the length of the film path for a liquid flowing under the action of gravity on the outside surface of a vertical tube.