bluuebunny/crossref_metadata_2025 huggingface dataset:
Mathematical modeling of geometrical and electrical characteristics of island films growth initial stages
Authors: Isaeva A A , Sidorova S V
Published: November 2019

The metal island nanostructures application fields in science and technology are presented. Experimental studies were carried out using the UVN-1M vacuum unit to test the metal thin films formation modes. Presents the control principle at the initial stages of growth of the tunneling current change between the island thin films. A series of copper and aluminum ITF samples were obtained. The derived samples thicknesses were measured using an atomic-force microscope, as a result, the dependence of the geometric and electrical characteristics of thin films and island nanostructures on the process parameters were simulated.
Mathematical simulation of particle impact on a fixed surface in the formation of powder coatings
Authors: Bogdanovich V I , Giorbelidze M G
Published: November 2019

The article deals with the process of elastic and plastic-elastic deformation of the particles during forming of the coating layer. Mathematical model of the process of impacting of powder particle on the fixed surface has been developed. Influence of material properties, kinetic and thermal parameters of deposition on the particle deformation has also been considered.
Modeling heat transfer in a supercritical carbon dioxide flow with greatly variable thermophysical properties
Authors: Chirkov A Yu , Luo T , Egorov K S
Published: November 2019

A mathematical model of carbon dioxide isobaric flow under supercritical pressure in the condition of a constant heat flux on the surface of a cooled pipe is discussed. Criterion dependencies for heat transfer are analyzed. The effect of greatly variable heat capacity is shown. A method has been developed for taking this factor into account in numerical calculations. Areas are found with the so-called degraded heat transfer.
Developing a microscopic city model in SUMO simulation system
Authors: Maiorov E R , Ludan I R , Motta J D , Saprykin O N
Published: November 2019

Modern high rates of urbanization affect the economic and social processes in cities around the world. One of the main problems in cities is the weakness of transport systems. To solve this problem, it is necessary to use specialized software for modeling, in consequence of the fact that there is no possibility to influence the situation in real time. The main problem in creating a transport model of cities is the lack of data on the mobility of residents. The aim of this work is to develop a method and software for automated creation of microscopic models of cities using open data. We propose the processing pipeline that consumes the open data about city population and transport infrastructure and produces routes for agents of microscopic simulation. The developed method was implemented using the Python programming language in the Zeppelin interactive environment. The software was tested on data from the city of Samara (Russia). The obtained results show acceptability of proposed method and possible ways to improve the accuracy of the model.
Simulation and optimization of the cargo terminal in the AnyLogic environment
Authors: Mokshin V V , Kirpichnikov A P , Soiko A I
Published: November 2019

The paper considers the formal theoretical bases of the analytical, simulation and optimization simulating of multi-channel queuing systems with waiting (with the unlimited and limited queue). The research is based on the use as an analytical platform of the simulation environment AnyLogic, which allows us to carry out simulation and optimization experiments, as well as perform parametric analysis of solutions and studies on sensitivity. Practical approbation of models is based on solving and researching a wide range of tasks on simulating queuing systems with an expectation from different subject areas. The basis of the methodology used for modeling and optimization is the provision of using as an optimization criterion (objective function) the total reduced costs in both service channels and queue losses. The research is aimed at reviewing and analyzing queuing systems with various event flows in the AnyLogic simulation environment.
Model of a real cycle of a power installation with a real-gas working fluid
Authors: Chirkov A Yu , Egorov K S , Ganeev K B , Zuev T R
Published: November 2019

The modelling of the working cycle of a closed cycle power installation with real gas is considered. The properties of a real gas are investigated using carbon dioxide as an example. The indicators of the real thermodynamic cycle of the installation when working on carbon dioxide are investigated. Particular attention is paid to the simulation of heat transfer in the recuperator.
Method of manual symmetrization of electric networks
Authors: Zakurdaev R Yu , Chernetskaya I E
Published: November 2019

The article describes a method of reducing asymmetry in the electrical network supplying the utility load. The essence of the method lies in the uniform distribution of loads by switching branches. The results of experimental studies are presented, confirming that the proposed method actually reduces the asymmetry of the network; and also reduces power loss and voltage loss during the transmission of electricity. It gives a comparison with the existing method of uniform distribution. The high efficiency of the proposed method has been experimentally proved.
Implementation of the FDTD method block algorithm in the MATLAB language using a graphics processing unit. 2D-decomposition case
Authors: Morunov N D , Golovashkin D L
Published: November 2019

The problem of limited video memory when organizing parallel computing using the FDTD method on a non-professional graphics processor was considered in this article. As a solution, a block algorithm of the FDTD method with 2-D decomposition and its implementation in the MATLAB language are proposed. As a result, the problem of limited graphics memory was solved, the maximum possible discretization of the grid in calculations on the GPU was expanded from 10 million to 85 million nodes with an average acceleration of 7,5 times for the two-dimensional case of the FDTD method.
Investigation of the multiple comparisons problem in the analysis of the wave train electrical activity of muscles in Parkinson’s disease patients
Authors: Sushkova O S , Morozov A A , Gabova A V , Karabanov A V
Published: November 2019

A new method has been developed for the analysis of the wave train electrical activity of muscles based on the wavelet analysis and ROC analysis that enables to study the time-frequency characteristics of electromyograms (EMG) and acceleration (ACC) signals in patients with Parkinson’s disease (PD). The idea of the method is to find local maxima (that correspond to the wave trains) in the wavelet spectrogram and to calculate various characteristics describing these maxima: the leading frequency, the duration of the wave trains in periods, the bandwidth of the wave trains, the number of wave trains per second. The degree of difference between a group of patients and a control group of volunteers in the space of these parameters is analyzed. ROC analysis is used for this purpose. The functional dependence of AUC (the area under the ROC curve) on the values of the boundaries of parameters’ ranges under consideration is investigated. The developed method involves investigation of a big number of ranges of selected characteristics; therefore a multiple comparisons problem appears during statistical hypothesis testing. It is necessary to find a compromise between the degree of detail of the studied characteristics and the magnitude of the Bonferroni correction. The paper describes the statistical hypothesis testing on the data of early Parkinson’s disease patients.
CUDA parallel programming technology application for analysis of big biomedical data based on computation of effectiveness features
Authors: Ilyasova N Yu , Shikhevich V A , Shirokanev A S
Published: November 2019

This paper proposes the technology for large biomedical data analysis based on CUDA computation. The technology was used to analyze a large set of fundus images used for diabetic retinopathy automatic diagnostics. A high-performance algorithm that calculates effective textural characteristics for medical image analysis has been developed. During the automatic image diagnostics, the following classes were distinguished: thin vessels, thick vessels, exudates and a healthy area. The study of the mentioned algorithm efficiency was conducted with 500x500-1000x1000 pixels images using a square 12x12 dimension window. The acceleration relationship between the developed algorithm and various data sizes was demonstrated. The study showed that the algorithm effectiveness can be affected by certain characteristics of the image, e.g. its clarity, shape of exudate zone, variability of blood vessels, and optic disc location.
Detection of epileptic seizures in EEG signals during long-term monitoring of patients after traumatic brain injury
Authors: Kershner I A , Sinkin M V , Obukhov Yu V
Published: November 2019

Long-term (several days) monitoring of epileptiform activity in scalp EEG of posttraumatic brain injury patients is an important task. EEG signals contain epileptiform seizures and similar signals of myographic activity associated with chewing. Both epileptiform activity and chewing artifacts appear in the same frequency range, which complicates their differentiation. To distinguish epileptiform activity from chewing artifacts, a method based on the wavelet spectrogram analysis of EEG is proposed. EEG wavelet spectrogram contains broadband peaks at times corresponding to peak-wave epileptiform activity on the one hand, and peaks of myographic activity at chewing on the other hand. The periodicity of these peaks is investigated. The difference in the period dispersion of epileptiform peaks and chewing peaks are found.
An SGD-based meta-learner with “growing” descent
Authors: Kulikovskikh I , Prokhorov S , Legović T , Šmuc T
Published: November 2019

The paper considers the problem of accelerating the convergence of stochastic gradient descent (SGD) in an automatic way. Previous research puts forward such algorithms as Adagrad, Adadelta, RMSprop, Adam and etc. to adapt both the updates and learning rates to the slope of a loss function. However, these adaptive methods do not share the same regret bound as the gradient descent method. Adagrad provably achieves the optimal regret bound on the assumption of convexity but accumulates the squared gradients in the denominator that dramatically shrinks the learning rate. This research is aimed at introducing a generalized logistic map directly into the SGD method in order to automatically set its parameters to the slope of the logistic loss function. The optimizer based on the population may be considered as a meta-learner that learns how to tune both the learning rate and gradient updates with respect to the rate of population growth. The present study yields the “growing” descent method and a series of computational experiments to point out the benefits of the proposed meta-learner.
Analysis of geomagnetic field data during periods of increased solar activity and magnetic storms
Authors: Mandrikova O V , Rodomanskay A I , Mandrikova B S
Published: November 2019

We present and describe an automated method for analysis of magnetic data and the detection of geomagnetic disturbances based on wavelet transformation. The parameters of the computational algorithms allow us to estimate the characteristics of non-uniformly scaled peculiar properties in the variations of the geomagnetic field that arise during periods of increasing geomagnetic activity. The analysis of geomagnetic data on the eve and during periods of magnetic storms was carried out on the basis of the method according to the network of ground stations. Periods of increasing geomagnetic activity are highlighted which precede and accompany magnetic storms. The dynamic of variation of the geomagnetic field in the auroral zone is considered in detail.
Detection of quasi-harmonic signals with a priori unknown parameters in strong additive noise by machine learning methods
Authors: Nevzorov A A , Orlov A A , Stankevich D A
Published: November 2019

Signals with a priori unknown parameters in strong noise are used in various fields of science and technology. This paper is devoted by features and limits deep neural networks for signal detection. We study quasi-harmonic signals with a priori unknown parameters. Neural network method was compared with classical methods for detecting signals in terms of accuracy and speed. We use realistic models of hexogen nuclear quadruple resonance (NQR) signals with parameters dependence by temperature. Experiments show that proposed method is more accurate and one hundred times faster than alternative ones. We achieve a probability of NQR signal detection about 95%, when signal-to-noise ratio is -15 dB and the signal parameters are unknown. When the signal-to-noise ratio is -20 dB, probability of NQR signal detection is 80%.
Binary data storage, retrieval and feature calculation on Netezza PureData system for Analytics
Authors: Donon Y , Paringer R , Kupriyanov A
Published: November 2019

The storage of images in databases has long been a delicate matter but comes now more and more in use. This kind of data is in most DBMS limited in storage size to 64kb, making necessary to divide large objects into fragments; moreover, programming languages also present limitations in data retrieval. In this paper, we experimented the retrieval, reconstitution, feature calculation of pictures using different fragment size and determined the optimal one. In this work, the server used was a Netezza model from the N2001 line. In this work, we present the architecture of the database, our research and bring recommendation about the optimal fragmentation size to store images into a database.
Evolutionary methods in modelling behaviour of complex system
Authors: Mokshin V V , Sharnin L M
Published: November 2019

In this paper, a recursive-regression approach is formulated in the formation of a functioning model of a complex system. The complex system consist of the object of study represented by a set of related factors. Some of these factors can be specified from the outside, whereas other factors contain information generated by system. We demonstrate that time-dependence of these factors can be reproduced by the nonlinear regression model. The proposed sub-course combines the method of group accounting of arguments with standard regression analysis adapted to fast dynamic processes. As an example, recursive-regression modelling of the functioning of an industrial enterprise was performed. This allows us to predict a possible behaviour of the system and to identify the so-called significant factors that have a significant impact on the behaviour of the system. To demonstrate validity of the method, we apply it to analyse the data characterizing a manufacturing company. Also paper includes meteorological data analysis. An important advantage of the proposed approach is that models for effective factors are formed automatically at each time step. The given results make possible to determine the optimal parameters of introduced algorithm and number of time observations for analysis.
Intelligent OFDM telecommunication system. Part 3. Anti-eavesdropping and anti-jamming properties of system, based on many-parameter wavelet and Golay transforms
Authors: Labunets V G , Komarov D E , Chasovskikh V P , Smetanin J G , Ostheimer E V
Published: November 2019

In this paper, we aim to investigate the superiority and practicability of many-parameter wavelet and Golay transforms (MPWT and MPGT) from the physical layer security (PHY-LS) perspective. We propose novel Intelligent OFDM-telecommunication system (Intelligent-OFDM-TCS), based on many-parameter transforms (MPTs). New system uses inverse MPT for modulation at the transmitter and direct MPT for demodulation at the receiver. The purpose of employing the MPTs is to improve the PHY-LS of wireless transmissions against to the wide-band anti-jamming communication. Each MPT depends on finite set of independent Jacobi parameters (angles), which could be changed independently one of another. When parameters are changed, multi-parametric transform is changed too taking form of a set known (and unknown) orthogonal (or unitary) wavelet transforms. We implement the following performances as bit error rate (BER), symbol error rate (SER), peak to average power ratio (PAPR), the Shannon-Wyner secrecy capacity (SWSC) for novel Intelligent-MPWT-OFDM-TCS. Previous research has shown that the conventional OFDM TCS based on discrete Fourier transform (DFT) has unsatisfactory characteristics in BER, PARP, SWSC and in anti-eavesdropping communications. We study Intelligent-MPT-OFDM-TCS to find out optimal values of angle parameters of MPT optimized BER, PAPR, SWSC, anti-eavesdropping effects. Simulation results show that the proposed Intelligent OFDM-TCS have better performances than the conventional OFDM system based on DFT against eavesdropping.
Method of analysis of cosmic ray data based on neural networks of LVQ
Authors: Mandrikova O V , Geppener V V , Mandrikova B S
Published: November 2019

An automated method for analysis of cosmic ray data and for detection of sporadic effects is described. The method is based on the application of multi-scale wavelet decompositions and neural networks of vector quantization. Using the method as the base, cosmic ray dynamics was investigated during increased solar activity and magnetic storms. Sporadic effects preceding and accompanying magnetic storms were detected. The method showed its efficiency for data real time analysis and detection of sporadic effects including those of low amplitude. The results are important in the tasks of space weather forecast.
Machine-learning algorithms for helicopter hydraulic faults detection: model based research
Authors: Gareev A M , Minaev E Yu , Stadnik D M , Davydov N S , Protsenko V I , Popelniuk I A , Nikonorov A V , Gimadiev A G
Published: November 2019

The problem of automatic reliability monitoring and reliability-centered maintenance is increasingly important today. In this paper, we compare the accuracy of four machine learning approaches for fault detection in a hydraulic system. The first three approaches are based on SVM classifiers with linear, polynomial and RBF kernels and the last one is a gradient boosting on oblivious decision trees. We evaluate algorithms on the synthetic dataset generated by our simulation model of the helicopter hydraulic system and show that high accuracy fault detection can be achieved.
Dynamical physically structured data modeling vs. classical time series analysis: A case study related to clinical trial data analysis
Authors: Semushin I V , Tsyganova Yu V
Published: November 2019

At the time series analysis’s core is the fitting of a preselected model—in the most straightforward case a linear combination of basis functions—to experimental data with one of the performance indices, for example, least squares criterion. However, no matter what the type of such a model is and whatever be the fitting performance index, such an approach does not stipulate for reliance on the understanding those dynamical laws of physics dictating the observable data behavior, given their complexity or uncertainty.

Our research looks into a question: “What benefits or advantages could mathematical modeling of such laws be capable of giving when included in nature or experimental data analysis?—nowhere more so than in deciding on life-changing events based on time series analysis in medical practice”.
Subject-oriented computing environment for solving large-scale problems of energy security research
Authors: Bychkov I V , Oparin G A , Feoktistov A G , Sidorov I A , Gorsky S A , Kostromin R O , Edelev A V
Published: November 2019

We represent a new approach to the development and use of a subject-oriented heterogeneous distributed computing environment for solving large-scale problems of energy security research. Both the development of scalable applications (distributed applied software packages) and the computing resources integration are conducted using the Orlando Tools framework. It supports the collaborative application development based on the continuous integration of their software. Computation management tools in Orlando Tools are integrated with a multi-agent system. We propose special multi-agent tools for the heterogeneous resource allocation in the environment. These tools apply knowledge about the subject domain specifics of solved-problems and computing environment characteristics. The effectiveness of such management is highlighted by the results of solving practical problems of energy security research.
Similarity-based decision tree induction method and its application to cancer recognition on tomographic images
Authors: Berikov V B , Pestunov I A , Kozinets R M , Rylov S A
Published: November 2019

The paper proposes a pattern recognition method using a modification of the class of logical decision functions presented in the form of decision tree. Instead of standard statements corresponding to the tree nodes, in which a variable is tested for a certain set of its values, a more general type of statements is used regarding the similarity of the point in question to different subsets of the observations. At the same time, to determine the degree of similarity, various metrics and subspaces of features can be used. This type of decision tree allows one to obtain more complex decision boundaries, which at the same time have a clear logical interpretation for the user. Several tree induction strategies are considered based on data transformation using support points selected with Relief, SVM, and k -means procedures. The method is experimentally investigated on the problem of tomographic images analysis, as well as on several synthetic datasets. Experiments have shown that the proposed method gives more accurate predictions than CART, SVM, kNN classifiers and deep convolutional neural network (AlexNet).
Recognition of Herpes Viruses on the Basis of a New Metric for Protein Sequences
Authors: Sulimova V , Seredin O , Mottl V
Published: November 2019

This paper addresses the problem of intellectual human herpes viruses recognition based on the analysis of their protein sequences. To compare proteins, we use a new dissimilarity measure based on finding an optimal sequence alignment. In the previous work, we proved that the proposed way of sequence comparison generates a measure that has properties of a metric. These properties allow for more convenient and effective use of the proposed measure in further analysis in contrast to the traditional similarity measure, such as Needleman-Wunch alignment. The results of herpes viruses recognition show, that the metric properties allow to improve the classification quality. In addition, in this paper, we adduce an updated computational scheme for the proposed metric, which allows to speed up the comparison of proteins.
Anomalies detection in social services data in the sphere of digital economy
Authors: Khripunov P V , Minaev E Y , Protsenko V I , Davydov N S , Nikonorov A V
Published: November 2019

This article addresses the study of the anomaly and fraud detection problem in the data from social services. The problem of detecting anomalies is extremely relevant for data-driven processes in the digital economy. In this paper, we propose a two-step approach for the detection of anomalies using auto-encoders and the conjugacy indicator. An experimental study of the efficiency of the proposed algorithms was conducted using open-access data set.
Management of thermal and mechanic flow characteristics in the output channels of a turbocharger centrifugal compressor
Authors: Plotnikov L V , Zhilkin B P , Brodov Yu M
Published: November 2019

It is known that the thermal and mechanical characteristics of the air flow in the output channel of a turbocharger compressor largely determine the effectiveness of the gas exchange processes quality of a piston engine. The studies were carried out on an experimental installation containing a turbocharger, output channels of different configurations, a measuring base, and a data collection system. It was found that stabilization of the flow in the compressor output channel leads to a significant increase in heat transfer intensity (up to 25 %) compared to the baseline pipeline while simultaneously reducing the turbulence number by up to 30 %. A more significant increase in heat transfer intensity (up to 30 %) was observed in the output channel of the compressor with grooves compared to the base channel while simultaneously increasing the turbulence number by up to 12 %. The proposed configuration of the output channels of the compressor can be used to intensify heat transfer for the natural cooling of the air during the intake process. The configuration with a leveling grid can be used to stabilize the gas-dynamic flow parameters in order to reduce the hydraulic resistance of the intake system of a turbocharged engine.
Spatial Temperature Distribution of an Open Square Capillary Tube Wall during Passage of a Taylor Liquid Plug
Authors: Ya Gatapova E , Khandekar S
Published: November 2019

Taylor plug/bubble flow is a predominant two-phase flow pattern occurring in several microfluidic devices such as in microchannel heat sinks, fuel cells, pulsating heat pipes, labon-chips, microreactors, etc. Such flows are characterized by an alternating sequence of liquid plug and gas bubbles, whose ensuing local transport characteristics (heat and mass transfer) are complex and still not fully understood. Presence of gas-liquid interfaces, thin-film dynamics, moving contact lines, wettability, contact angle hysteresis, are some of the physical phenomena involved in Taylor bubble flow systems that manifests into its complex transport characteristics. Understanding the local interfacial transport mechanism is of vital importance to develop a comprehensive model for micro-scale devices utilizing Taylor bubble flow. In this background, we probe locally into the local thermo-hydrodynamics of ‘unit-cell’ of Taylor plug flow, which is essentially an isolated liquid plug moving inside a mini square capillary copper tube (side = 2 mm), surrounded by gas from both its sides, and try discerning local evaporation dynamics, with the help of IR thermography. This study focuses on the interplay of conjugate conduction, local thin film hydrodynamics formed behind the moving liquid plug, and its subsequent evaporation. We obtain local temperature distribution in the meniscus region, as the plug moves through the capillary tube. As the cold plug passes through the tube, local temperatures drop drastically, the transient reaches the heater-tube interface a bit delayed and there the drop in temperature is modest. The study clearly reveals that there is a strong thermo-hydrodynamic coupling between the tube wall and the moving Taylor liquid plug.
Influence of the thermal parameters on the bubble heat balance at transient boiling of subcooled water
Authors: Levin A A , Khan P V
Published: November 2019

This paper considers the development of the approach presented [1–3] to the determination of heat trasnfer in subcooled boiling flow additively from the components of forced convection and heat fluxes associated with the presence of bubbles on the surface. The case of non-stationary heat release in a vertical channel with an uprising fluid was numerically studied on the basis of the experimental data from [5]. We have studied the effect of the fluid subcooling and the heat flux on the characteristics of transient boiling.
Flow structure and heat transfer in a turbulent vertical bubbly flow downstream of a sudden duct expansion
Authors: Chinak A.V. , Lobanov P.D. , Pakhomov M.A.
Published: November 2019

The flow structure and heat transfer in bubbly flows in a sudden duct expansion were studied. The data was obtained both in a pipe and a flat channel with a sudden expansion. Measurements are performed using shadow photography and PIV/LIF system. For modelling two-phase bubbly flow the set of RANS equations is used. Reynolds stress transport model is used to predict the turbulence of the liquid phase. The influence of sudden channel expansion on the distribution of bubbles and it`s velocity is shown. It is shown, that in the pipe with sudden expansion there are not a strong influence of bubbles on the hydrodynamical structure and heat transfer in the flow recirculation zone. In a contrast, in the vertical channel with back facing step the strong increasement of void fraction were found in similar region. It can result in increasement of heat transfer.
Formation of thermocapillary structures in heated liquid film
Authors: Chinnov E A
Published: November 2019

Data on the formation of thermocapillary structures and breakdown of a heated liquid film flowing down a vertical surface with Reynolds number variation from 0.1 to 500 have been analyzed and generalized. Small-scale thermocapillary structures are distinguished. It is shown that the distances between temperatures heterogeneities (rivulets) of thermocapillary structures do not depend on the Reynolds number. It is determined that the interaction of waves with thermocapillary structures leads to an increase in the critical heat flux corresponding to the liquid film breakdown as compared with the data of publications.
Effect of steam supply to the air-blown gasifier on hot syngas desulphurization
Authors: Nikitin A D , Abaimov N A , Butakov E B , Burdukov A P , Ryzhkov A F
Published: November 2019

The IGCC technology serves to efficiently produce thermal and electrical energy with minimal impact on the environment. In operating IGCC, wet desulphurization is used at temperatures below 200°C. The use of hot desulphurization at temperatures around 500°C will significantly improve IGCC efficiency. The preferred sorbent for hot gas cleaning is ZnO. At temperature of 450-500°C, ZnO begins decomposing because of reactions with syngas components (primarily hydrogen). Steam impedes reaction of ZnO with H2 and increases ZnO thermal stability. Syngas H2/H2O ratio is determined by gasifier operation mode. The purpose of this work is to determine maximum temperature of hot gas cleaning depending on condition of ZnO-sorbent thermal stability and steam-air-blown mechanically activated coal gasifier operation mode. To determine the effect of steam supply to syngas composition, experiments were performed on entrained-flow gasifier (1 MW). Experimental results were processed using thermodynamic analysis to determine idealized syngas composition and CFD-modeling to determine real experiment process parameters. Syngas H2O content was determined by CFD-modeling results. Study of ZnO-sorbent thermal stability depending on H2 concentration and syngas H2/H2O ratio was performed by TGA. As a result of experimentally confirmed thermodynamic calculations, ZnO-sorbent thermal stability was found to increase to 815°C due to steam dilution.
Investigation of applicability area for turbulence models in the problems of mass transfer intensification by the control of a rotary divergent flow
Authors: Kabardin I.K. , Pravdina M.Kh. , Yavorsky N.I. , Polyakova V.I. , Meledin V.G. , Ezendeeva D.P. , Kakaulin S.V. , Gordienko M.R. , Kulikov D.V. , Sadbakov O. Yu. , Klimonov I.A. , Usov E.V.
Published: November 2019

The fundamental scientific problem of this kind arises in mechanics, chemistry and catalysis in the intensification of mass transfer. The turbulent mass transfer characteristics were analyzed experimentally in a controlled rotational-divergent flow. The laser Doppler anemometry was used for turbulent mass transfer diagnostic. The verification of numerical calculations by computational hydrodynamics has been carried out according to the results of experimental studies. Calculation of turbulent kinematic is build on solving of a system of continuity and the Navier-Stokes equations. The fluid is incompressible and isothermal. For averaged equations closure, semi-empirical turbulence models were used: the k-ε model of turbulence and the Reynolds stresses transfer model. The calculation has showed the existanceof a near-wall jet after a rotating device and the generation of reverse flow zones. Comparison with experimental data has shown that all models of turbulence adequately model the rotational-divergent flow only until the formation of flow gaps and the formation of reverse flow zones. The discrepancy with the experiment occurs while controlling the flow to equalize the velocity profiles.
Investigation of high speed steam jet effect on combustion of substandard liquid hydrocarbons
Authors: Kopyev E.P. , Anufriev I.S. , Osintsev Ya.A. , Mukhina M.A.
Published: November 2019

Combustion of liquid hydrocarbon fuel dispersed by superheated steam jet was experimentally studied. Characteristics of the combustion process (heat release, emission of toxic products, flame temperature) were investigated in a laboratory direct-flow atmospheric burner (capacity up to 20 kW) at different operating systems with waste transmission automotive oil as fuel example. Regimes were found which provoke stable combustion of non-quality liquid hydrocarbons. It was shown dependences of heat, flue gas parameters on superheated steam flow rates, fuel flow rates, flame temperatures.
Effect of the angle of rotation of structured packing layers on separation efficiency in distillation column
Authors: Pavlenko A N , Pecherkin N I , Zhukov V E , Nazarov A D , Meski G , Houghton P
Published: November 2019

It is well known that a good quality of liquid distribution over the surface of structured packings is crucial for high performance of large diameter columns. The angle of rotation of the packing layers and their number are among the main parameters characterizing the distribution of liquid in a structured packing over the column cross-section and height. This paper presents investigation results on the influence of the rotation angle of structured packing layers on separation efficiency, pressure drop, distribution of local composition of mixture and local liquid flow rate under the packing. The experiments were carried out in distillation column with the internal diameter of 0.9 m on a structured packing with a specific area of 500 m2/m3, and the corrugation angle of packing equal to 45°. The mixture of refrigerants R114 and R21 at the pressure of 3 bar and total reflux was used as the working fluid. The column was packed with 11 packing layers with rotation angles of 20, 45, 70, and 90 degrees. According to experimental results, a decrease in the angle of packing layer rotation from 90 to 20 degrees leads to a decrease in separation efficiency, while the HETP value increases by 10–12%.
Effect of the wall properties on the shock wave / laminar boundary layer interaction
Authors: Kutepova A I , Polivanov P A , Sidorenko A A
Published: November 2019

The CFD calculations have been performed based on RANS approach with the Menter transition model [1]. The boundary layer developing on a flat plate was considered. To generate the incident shock wave, a wedge was installed over the plate. The wall was represented by one cm thick solid flat plate made from aluminum and polyacetal. Flow parameters were M∞=1.41, P0=0.7 bar, T0=293K. As a result of solving the conjugate heat transfer problem, the SWBLI flow was studied. The temperature and pressure distributions on the wall for different surface materials were obtained. It was found that the streamwise heat fluxes inside the wall can lead to a change of the separation zone length.
Stretched flame behavior in a planar meso-scale channel with heat conducting walls
Authors: Mokrin S , Sharaborin D , Odintsov E , Uriupin G , Minaev S
Published: November 2019

The influence of the wall on flow field, combustion regimes and flame extinction limit of premixed methane/air flames stabilized in the planar channel with heat conducting walls was experimentally investigated. Experimental data were compared with the results obtained in previous theoretical works. The influence of channel walls on gas flow was estimated by using PIV experiments with non-reacting gas flow and compared with the results of numerical simulation.
Experimental research of supersonic flow heat transfer in the wake of a backward-facing step
Authors: Leontiev A I , Popovich S S , Vinogradov Y A , Strongin M M
Published: November 2019

The results of an experimental study of heat transfer for a supersonic flow behind a backward-facing step are presented. Input flow Mach number was 2.2, Reynolds number was over 20 million when calculated with the use of the dynamic boundary layer length from the critical section to the exit section of the nozzle. The height of the step ranged from 8 to 14 mm. The thickness of dynamic boundary layer for plane model flow was about 6 mm in the region of nozzle exit section. The heat transfer coefficient and adiabatic wall temperature for the wake flow behind the step have been analysed in comparison with the plane model flow. The experiment was made with the use of chromel-kopel thermocouples with thermal compensation of cold junction, stagnation and static pressure meters, NI LabView powered programs of experimental automation. The graphs of the wall temperature, stagnation flow temperature, adiabatic wall temperature, the stagnation and static pressure, the distribution of the temperature recovery coefficient and the relative Stanton number along the model length are presented.
A laboratory setup based on porous burner for coal particles combustion investigation
Authors: Ponomareva A A , Tcoi K A , Mokrin S N , Shtym K A
Published: November 2019

In this work, physicochemical features, thermal behaviour, and combustion properties of a coal dust of Pavlovskiy brown coal were studied. For investigations of kinetic properties of fine coal particles combustion, the laboratory-made setup was developed and constructed. An experimental research on the properties of fine coal particles was carried out. Additionally, thermophysical characteristics of coal dust, compositions of thermal decomposition products and particle size distribution were investigated.
Results of Thermal Tests of Recirculation Cooling Installations
Authors: Balunov Boris , Lychakov Vitalii , Egorov Mikle , Sheglov Andrey , Suhorukov Yurii
Published: November 2019

The article presents the results from thermal tests of some recirculation installations for cooling air in nuclear power plant premises, including the volume under the containment. The cooling effect in such installations is produced by pumping water through its heat-transfer tubes. Air from the cooled room is blown by a fan through a bundle of transversely finned tubes and is removed to the same room after having been cooled. The finning of tubes used in the tested installations was made of Grade 08Kh18N10T and Grade 08Kh18N10 stainless steels or Grade AD1 aluminum. Steel fins were attached to the tube over their entire length by means of high-frequency welding. Aluminum fins were extruded on a lathe from the external tube sheath into which a steel tube had preliminarily been placed. Although the fin extrusion operation was accompanied by pressing the sheath inner part to the steel tube, tight contact between them over the entire surface was not fully achieved. In view of this, the air gap’s thermal resistance coefficient was introduced in calculating the heat transfer between the heat-transferring media. The air gap average thickness was determined from the test results taking into account the gap variation with temperature due to different linear expansion coefficients of steel and aluminum. These tests were mainly aimed at checking if the obtained thermal characteristics were consistent with the values calculated according to the standard recommendations with introduction, if necessary, of modifications to those recommendations.
Experimental investigation of freon mixture spreading over the structured Sulzer 500X packing at single drip point irrigation
Authors: Zhukov V E , Pavlenko A N , Yu Slesareva E , Pecherkin N I , Meski G , Houghton P.
Published: November 2019

The paper presents the results of experimental studies on liquid spreading over the Sulzer 500X packing at single drip point irrigation. The experiments were carried out using a 10% mixture of R114/R21 freons on one packing layer with a diameter of 0.6 m. The flow rate of liquid flowing from the lower edge of the packing was measured automatically by a flow meter moving along the packing sheets with a given step. The flow meter used volumetric measurement method. The receiving collector of flow meter is 50x50 mm in size, operating range of flow measurement is 0.05–50 ml/s. Distributions of liquid over the packing were measured at single-jet irrigation in the range of jet flow rates 2.5 < q
irrig < 60 ml/s. Spreading zone in the case of irrigation by a single jet is limited by the corrugation channels coming from the irrigation point. The pattern of spreading at low-flow jet irrigation has the shape of a dome with a low flow rate at the outlet of corrugation channels, which limit the spreading zone. With an increase in the flow rate, the share of liquid in these channels increases and dominates over other parts of the spreading zone.
Pore scale numerical simulation of heat transfer in propagating thermal wave during filtration combustion of rich and lean methane-air mixtures
Authors: Yakovlev I A , Zambalov S D
Published: November 2019

The porous media combustion phenomenon was numerically studied with focus on the heat transfer effect in propagating combustion wave for lean and ultra-rich mixture compositions using the approach when the three-dimensional porous structure and interstitial flow are simulated directly at pore scale with explicit consideration of the thermal interaction between fluid and solid phases including the detailed chemical kinetics model and solid-to-solid radiation. The results demonstrate that irregularity of the porous structure leads to a large spatial variation of the process parameters and the flow inhomogeneity. The most intensive heat sources placed within the cavities where the flow is developed. During the process, the interface heat transfer and radiation contribute to heat recuperation mechanism that leads to thermal non-equilibrium in the combustion wave. The heat is transferred through the bed via radiation layer-by-layer due to restricted visibility of the particles. The numerical data about a local variation of the process parameters were presented. The data of this type can be used for modification of the volume-averaged models within the context of spatial variation consideration. It was shown that there is a correlation between the heat release rate, the interface heat flux, the radiative heat flux, and its root mean square values.
Heat transfer and dynamics of transient processes at liquid film flowing on smooth and modified surfaces
Authors: Pavlenko A N , Kuznetsov D V , Volodin O A , Zubkov N N
Published: November 2019

The paper presents the results of an experimental study on propagation dynamics and structure of the wetting front under adiabatic conditions and on a preheated surfaces with a needle-like microstructure, as well as heat transfer and critical heat fluxes at a film flow of liquid nitrogen. The surface was structured by the method of deforming cutting (MDC). A comparison with the data obtained on a smooth plate was performed. Data of high-speed video of the processes are presented.
Heat pipe: a simple one-dimensional model and an experimental study
Authors: Cheverda V V , Vozhakov I S , Ronshin F V
Published: November 2019

In this work the authors proposed to use 1-D model for heat and masstransfer calculations inside a porous heat pipe. Several limits are taken in to account: sound, boiling, capillary and dry out of evaporator. To calculate the heat flow, we analyzed processes in four zones: the evaporator, the condenser, the porous body in which fluid flows, and the cavity in which steam flows. We assume that in the evaporator all the incoming liquid evaporates, and in the condenser, all the vapor condenses. The liquid and the vapor are in a state of saturation and, therefore, the pressure in the condenser and the evaporator is equal to the saturation pressure. The good agreement between theoretical and experimental results is observed.
The heat transfer crisis in shear driven water film
Authors: Cheverda V V , Ponomarenko T G
Published: November 2019

In this work the authors demonstrate efficiency of thin water film, shear driven by gas flow in the mini-channel with local heater. The effect of microgrooves on heating surface is demonstrated. It is shown that microgrooves on the heating surface can provide an increase in the critical heat flux due to the capillary effect of microgrooves.
Vapour bubble dynamics in a flat mimi-channel under intense heating
Authors: Belosludtsev V V
Published: November 2019

Investigation of subcooled nucleate boiling in minichannels was conducted with high speed recording optical system also equiped with high spatial resolution optics. Obtained data on the bubble dynamics is in good agreement with well-known correlations from the literature. The final stage of bubble dynamics is in good agreement with the Labuntsov correlation for spherical vapor bubble growth on a heated wall.
Simulation of flows with phase transitions and heat transfer using mesoscopic methods
Authors: Kupershtokh A L , Medvedev D A
Published: November 2019

We use mesoscopic lattice Boltzmann and phase-field methods to simulate the growth of crystals from supercooled melt in the presence of melt convection and the behavior of a pinned droplet under the action of the electric field. In the first problem, the flow influences significantly the shape and the stability of growing patterns, leading to the enhanced development of fingers in the direction opposite to the flow. In the second problem, after the application of the electric field, the droplet begins to elongate in the field direction and the oscillations are produced. These oscillations decay in time due to a viscosity of a fluid. After several oscillations, the droplet acquires its equilibrium shape. The contact angle is essentially reduced compared to the case without an electric field.
Calculations of shock-wave flow structure in axisymmetric channel with near-wall ethylene burning with throttle air jet
Authors: Zamuraev V P , Kalinina A P , Fedorova DV , Popova D.S
Published: November 2019

The CFD modelling of the ramjet start with low losses of the stagnation pressure was carried out. The basic feature of this start technology was the jet of compressed air creating effect of a throttle which aids in preliminary decelerating of the flow up to transonic velocities. The comparison with experiment was performed for the hydrogen burning. We studied the axial and near-wall supply of gas fuel. The physical mechanisms stimulating stable presence of transonic mode in the part with constant section were investigated within the frameworks URANS approach. It was shown that fuel supply blockage is a way to control near-wall supplying of gaseous fuel at considerably low pressure falls. And blocking the ignition processes is a way to control the axial supply at quite high pressure falls.