bluuebunny/crossref_metadata_2025 huggingface dataset:
Environmental assessment of the quality of the Elek and Or rivers in the zone of influence of enrichment waste and metallurgical production
Authors: Kairakbaev A K , Abdrakhimov V Z , Abdrakhimova E S
Published: September 2020

The greatest threats for the environment are the dusts and sludges of ferrous metallurgy industry dispersed by wind during storage. For the Elek river, the threat is the ferro-dust, and for the Or, the main hazard is the sludge tailings. The performed survey has shown that the Elek and Or waters belong to the 4th class with the water pollution index of 4.15 for the Elek and 4.10 for the Or, which is interpreted as “polluted waters”. Throughout the entire length of the Elek and Or rivers the water quality class varies from 4 (polluted water) to 6 (very filthy water). The hexavalent chromium (Cr6+) content in the Elek River is 4.2 of the threshold limit value; the trivalent chromium (Cr3+) content exceeds the threshold limit value by 3.0 times; for the Or, these values exceed the threshold limit value by 2.2 and 1.5, respectively. Hexavalent chromium belongs to Group 1 carcinogenic substances. In both rivers, the boron threshold limit value value was also found to be exceeded; for example, boron B3+ (trivalent boron) content in the Elek river was found to exceed the threshold limit value value by 7.8 times, and in the Or, by 2.8 times. The present paper is intended to demonstrate that the recycling of large-tonnage wastes, such as the ferro-dust and sludge tailings, in the production of such stock commodities as ceramic bricks may facilitate the proper industrial waste disposal and protection of the industrial environment.
Formation of greenbelts as an environmental protection tool
Authors: Oznamets V V , Belokonev G V
Published: September 2020

The objective of this paper is to study the mechanisms and processes of functioning of the suburban forest and parkland zone of a big city and analyze the models of its formation. This paper contains a description of urban air self-purification mechanism with the use of forest park green belts and water surfaces. The article introduces the concept of an ecological network. The ecological network includes green belts and water areas, primarily, rivers. To build an ecological network, it is necessary to apply 3D and information modelling. The article describes three main greenbelt formation models. The article recommends the development and formation of greenbelts as multipurpose models and ecological networks.
To the forecast of residual resource installation of electric centrifugal pump for oil production
Authors: Topolnikov A S , Gimaltdinov I K , Gimaltdinova A A , Kochanova E Y
Published: September 2020

The results of numerical modeling of the operation of a well equipped with electric centrifugal pump installations under conditions of a gradual deterioration of pump characteristics (head, flow rate, efficiency) are presented. In this case, the residual resource of the installation is estimated as a period of time during which, due to a gradual increase in frequency, it is possible to maintain a constant flow rate of the well. Recommendations are given for determining the residual life in the field based on indirect measurement of pump performance degradation. A method for determining the residual life of a well equipped with installations of electric centrifugal pumps under abrasive wear conditions is proposed.
Analytical calculations of the parameters of pollutant emissions and the justification of methods for reducing surface gas pollution from working aircraft engines
Authors: Zvyagintseva A V , Kulneva V V , Sazonova S A
Published: September 2020

The estimation of pollutant emissions from a mobile diesel generator for starting aircraft engines recorded the following qualitative composition of the exhaust gas mixtures from the aircraft: CO, NOx (total NO2 and NO), C, CH (total hydrocarbons), SO2, CH2O, C20H12 (3,4-Benzpyrene). An analytical calculation was made from a stationary diesel generator of maximum and gross emissions of individual i-th pollutants. A quantitative assessment of pollutant emissions from racing tests of aircraft engines on bench measuring systems has been implemented. An analytical calculation was made of the characteristics: the amount of i-pollutants during the take-off and landing cycle, departing from the aircraft, gross emissions for 2 types of engines ICE-1 and ICE-2, and the most sold for bench runs of aircraft engines. The calculation of the maximum one-time amount of pollutants emanating from a source of pollution into the atmosphere is fixed taking into account the limiting factor - by the maximum emission concentration, this is for ICE-2. It was established: analytical calculations for the second test site recorded that, during control diagnostics of the operability and reliability of aircraft power plants on bench measuring systems, nitrogen oxides and carbon monoxide also prevailed in emissions from engines.
Potential possibilities of hydrogen accumulation in Nickel-based solid-state materials
Authors: Zvyagintseva A V
Published: September 2020

A variant of a hydrogen accumulator based on electrochemical systems has been investigated. Niwas used as the basis, as a material with a greater tendency to absorb hydrogen. Nix-By-H (D)z composites were synthesized by the electrochemical method. Adding B to the Nix-By composite increases the accumulation of hydrogen. In Ni-B composites, boron plays the role of a hydrogen atom catcher, since tensile stresses arise in the vicinity of the substitutional impurity of a small atomic radius - boron placed in the FCC nickel lattice, therefore, hydrogen, as compared to nickel, segregates with higher synergism near boron. The potential of interaction of a hydrogen atom with an impurity trap in the form of a boron atom is estimated at 42 eV. The thermal desorption spectra of deuterium were studied of Ni–B composites at T ~ 100 K, pre-implanted with deuterium (testing element). The ratio of Ni and deuterium Ni: D = 1:1, and for the composite Ni95B5 [Ni95: B5]: D = 1:1.25. Desorption peak - 325 K.
On the decomposition of gas hydrate at a positive temperature
Authors: Tazetdinov B I , Chiglintseva A S , Gimaltdinov I K , Kochanova E Y
Published: September 2020

This paper presents a study of the decomposition of hydrate at a positive temperature, taking into account the flowing down water from its surface. Two cases of decomposition of a cylindrical sample of a hydrate are considered, the first – the generatrix of the cylinder is located vertically, the second – the generatrix is located horizontally. It is shown that the decomposition rate is higher for a horizontally located hydrate sample. It was found that at a higher temperature (287 K), the intensity of decomposition of gas hydrate samples increases and the time for complete decomposition of vertical and horizontal samples begins to be 122 s and 105 s, respectively.
Environmental assessment of the impact of the meteorological conditions on technogenic formaldehyde and carbon black pollution of the air in Voronezh
Authors: Kurolap S A , Klepikov O V , Yeprintsev S A
Published: September 2020

Based on the Voronezh hydrometeorological service official statistics analysis, the pollutants (formaldehyde and carbon black) dynamics regularities depending on the various meteorological parameters combination - air temperature, wind speed, relative humidity. A positive relationship was established between atmospheric pollution growth with formaldehyde and air temperature. As the wind speed and the air relative humidity increase, the formaldehyde and soot concentration in the urban atmosphere, as a rule, decreases. The carcinogenic risk maximum permissible level to public health, causing concern, has been established. The obtained patterns can be used to predict the city’s atmosphere technogenic pollution level depending on meteorological conditions. Based on the official statistic analysis from the Voronezh Hydrometeorological Service, the pollutants (formaldehyde and carbon black) dynamics patterns are investigated depending on various meteorological parameters’ combination - air temperature, wind speed, relative air humidity. A positive relationship has been established between the increase in atmospheric pollution with formaldehyde and air temperature. With increasing wind speed and relative humidity, the formaldehyde and soot concentration in the city atmosphere, as a rule, decrease. The maximum permissible carcinogenic risk level to public health has been established, causing concern. The obtained patterns can be used to predict the city’s atmosphere technogenic pollution level, depending on meteorological conditions.
The use of ash and slag material from the Aktobe thermal power plant in the production of porous aggregates based on liquid glass compositions contributes to the development of a green economy
Authors: Kairakbaev A K , Abdrakhimov V Z , Abdrakhimova E S
Published: September 2020

The use of energy waste from thermal power plant ash and slag materials in the production of building ceramic materials helps to relieve environmental tensions in the regions, develop a “green” economy and transport and logistics infrastructure. Studies have shown that the ash-slag material has an increased content of organic matter (loss during calcination of 19-21%), carbon (C=7.8%) and calorific value (1600 kcal/kg), which will burn out or contribute to burning (for example, calorific value), creating porosity in the ceramic material. On the basis of liquid glass modified with sodium chloride and ash-slag material of the Aktobe TPP, a porous aggregate with high physical and mechanical parameters was obtained without the use of natural traditional raw materials (natural thinners, clay binders, etc.). Given that many ceramic factories to produce products for construction purposes as well as thermal power plant, located in the city or near the city, transport and logistics infrastructure can be solved more effectively through the use as a raw material slag material of a thermal power plant.
Revising the effectiveness of thermal method application for unconventional bitumen oil production stimulation
Authors: Gizzatullina A A , Tazetdinova Yu A
Published: September 2020

A theoretical model of petroleum reservoir engineering process with high viscosity oil using the technology of double horizontal wells is proposed. Numerical solutions of the problem in a two-dimensional formulation are obtained. With this method of producing high viscosity oil the efficiency of oil reservoir development can be increased by ensuring uniform heating of the developed zone of the field. The proposed model allows us to trace the two-dimensional picture of oil filtration in the reservoir and investigate the main regularities of the process. The costs for oil reservoir heating, flow rate development and changes in the mass of pumped oil in the initial period of well operation are determined. The obtained solutions for a long stretch of time were extrapolated.
The dynamics of sound waves in a tube with elastic walls filled with gas-liquid mixture
Authors: Gimaltdinov I K , Gizzatullina A A , Gimaltdinova A A
Published: September 2020

A theoretical model, describing the dynamics of sound waves in an elastic thin-walled tube, filled with bubble fluid is proposed. The dispersion equation is obtained, on the base of which the numerical values of the phase velocity and the logarithmic decrement are obtained. It has been established that for sound waves extending over the bubble fluid, which is located in a tube with elastic walls, there is a frequency band that is characterized by a strong wave damping. It is shown that the value of the phase velocity of sound waves in a bubbly liquid in the low-frequency region for an elastic tube is lower than that of a similar parameter in the case of a tube with “rigid” walls.
Contributions of VT and VV exchanges to the CO2 relaxation in the full state-to-state modeling
Authors: Gorikhovskii V , Nagnibeda E
Published: September 2020

Numerical modeling of nonequilibrium state-to-state carbon dioxide kinetics is a computationally complex problem requiring the solution of a huge system of stiff differential equations. In the present study, we use parallel numerical scheme, based on the extended backward differential formula with adaptive timestep strategy. Using this scheme, we study the contribution of various types of energy exchanges to the solution of kinetics equations. The comparison of the results obtained with the use of the ”cut” and full state-to-state approaches is also shown in the paper.
Critical stress analysis for the basis of a denture prosthesis
Authors: Arutyunov S D , Nikitin A D , Grachev D I , Bagdasaryan G G
Published: September 2020

This paper is focused on the numerical simulations for the mechanical behavior of the prosthesis basis under typical chewing loads. The model is supplied by physically correct boundary conditions. The stress analysis in the prosthesis basis is performed for the cases of symmetric and not-symmetric loading conditions. The sets of numerical calculations were performed for all the stages of food chewing. It was found that not-symmetric loading has a higher influence on the structural integrity of the prosthesis. The significant stress amplitudes on the basis were found under the loading at the block I (incisors) and block II (fang). It is shown that the maximum stress due to typical chewing loading usually cannot produce the prosthesis fracture in one cycle. However, the stress level is high enough to produce the fatigue crack initiation.
Smooth reconstruction method for surfaces defined by a continuous set of triangles
Authors: Kh Abuziarov M , Chekmarev D T
Published: September 2020

The paper considers the problem of triangular grids distortion in three-dimensional space, approximating the boundaries and interfaces of interacting solid, liquid and gaseous media. Unacceptable deformations of the mesh cells size and shape can occur during the numerical solution of continuous media dynamics problems. A method and algorithm for rebuilding grids using smooth piecewise polynomial interpolation by algebraic polynomials of the third degree is proposed.
Stability of the collinear point L
1 in the planar restricted photogravitational three-body problem in the case of equal masses of primaries
Authors: Bardin Boris S , Avdyushkin Andrey N
Published: September 2020

The planar restricted photogravitational three-body problem is considered. The motion of an infinitesimal small body (particle) under the Newtonian gravitational attraction of two bodies (primaries) is studied. It is supposed that primaries having equal masses move in weakly elliptic orbits and act on the particle with radiation pressure repulsive forces. Using the method of normal forms, the nonlinear stability study of the collinear point L
1 is performed and rigorous conclusions on stability in the sense of Lyapunov or formal stability are obtained.
Experimental study on viscous fingering in Hele-Shaw cell under acoustic impact
Authors: Marfin E A , Garaeva S V , Abdrashitov A A
Published: September 2020

Viscous fingering shaped as curvature of the fluid displacement fronts are usually formed in porous media and Hele-Shaw cell when a liquid with a high viscosity is displaced by a liquid with a lower viscosity. Such interfacial instability is undesirable in many displacement processes, and mainly in oil production. We present the results of physical modeling of the displacement of viscous oil by air in Hele-Shaw cell. As a method of suppressing undesirable interphase instability, the effect of elastic vibrations on the process is proposed. The experiment was performed in stationary conditions and under acoustic action on the displacement process. In the absence of superimposed vibrations, the growth rate of viscous finger is 2.15 times higher than the speed of liquid flow at the cell border. The imposition of acoustic oscillations can both accelerate and slow down the growth rate of viscous fingers depending on their frequency. The paper discusses the peculiarities of the development of viscous fingering. The results are compared with the calculated data.
A new numerical approach for solving initial value problems with exponential growth integral curves
Authors: Kuznetsov E B , Leonov S S , Tsapko E D
Published: September 2020

Some physical processes raised in aerodynamics, hydrodynamics, and theory of catalytic reactions are modeled by stiff initial value problems. This paper considers a class of stiff problems such as singularly perturbed problems for ordinary differential equations. Singularly perturbed problems have regions of rapid change in the solution, which are called contrast structures. Most often, boundary layer exhibits in such problems, but several pieces of research devoted to inner layers too. There are many numerical and asymptotic methods for solving singularly perturbed initial value problems with contrast structures. However, it is still an open field for researches because the universal method does not exist. Problems with an exponential growth rate of integral curves have a particular interest for researchers because most of the methods for solving singularly perturbed problems cannot handle these. We are going to discuss methods for solving singularly perturbed initial value problems with contrast structures. Also, we are proposing a new technique based on the method of solution continuation for problems with the exponential growth of integral curves. This technique allows explicit numerical methods to get the solution of the considered problem when it seems impossible for them. The efficiency of the new approach will be shown on the test initial value problem.
Features of aggregation of fuzzy expert judgments
Authors: Sudakov V , Sivakova T
Published: September 2020

The paper discusses methods of aggregating fuzzy judgments of experts based on fuzzy weighted sums and fuzzy areas of preference. The study is based on soft calculations. The approach based on fuzzy weighted summation allows you to take into account the degree of trust in the expert and his qualifications. The fundamental nature of the study is determined by the fact that the proposed approaches are invariant with respect to the subject area, it will allow you to effectively solve the problems of supporting the adoption of group decisions in case of fuzzy preferences. The authors developed algorithmic and software methods on the portal http://ws-dss.com.
Using GRU based deep neural network for intrusion detection in software-defined networks
Authors: Kurochkin I I , Volkov S S
Published: September 2020

This paper considers the possibility of using machine learning methods in solving the problem of intrusion detection in software-defined networks (SDN). The work is devoted to the research and development of a network attack classifier, which is a core of the intrusion detection systems. To evaluate the methods, an existing data set was used, which includes network traffic records with a several different network attack scenarios. A comparison of machine learning methods implementing neural networks on a selected data set is presented. Based on the results, it can be concluded that the task of intrusion detection in software-defined networks can be successfully solved using deep neural networks.
Estimation of the contribution of geophysical perturbations to the Earth pole oscillatory process at the precession frequency of the lunar orbit
Authors: Krylov S S , Perepelkin V V , Filippova A S
Published: September 2020

The contribution of the main geophysical perturbations (atmospheric and oceanic) to the oscillatory process in phase with the precession of the lunar orbit is investigated. The solutions for the differential equations of Earth pole motion are obtained, taking into account the atmospheric angular moment and the oceanic angular momentum, and the combination harmonics associated with the oscillatory process under consideration are identified. It is shown that the harmonics found are partially caused by fluctuations in the mobile media of the atmosphere and ocean.
Fluid flow modeling in solid rock fractures
Authors: Cherednichenko I N
Published: September 2020

This paper considers the solution of the problem of modeling fluid flows occurring while filling solid rock fractures with fluid under pressure. For the mathematical modeling of the solid rock, real data of the rock core sample density was used, obtained in the imaging process of Synchrotron radiation X-ray tomographic microscopy. A calculation method of computational grid cell effective volume, which takes into account rock permeability parameter and is based on tomographic data, is described. To simulate the fluid behavior the modified finite volume method, widely used in hydrodynamics, was applied. Its modification is described for calculating the medium with a variable permeability. The results of numerical experiments are presented.
Solving equations of 3D elasticity for orthotropic bodies
Authors: Revenko V P , Bakulin V N
Published: September 2020

A mathematical model of the three-dimensional orthotropic body was used. A technique has been developed for integrating equilibrium equations in displacements that describe the stress state of orthotropic materials. We find the solution of equilibrium equations in displacements for orthotropic bodies. The expression of displacements, strains and stresses is obtained through the introduced displacement function, which satisfies the sixth-order equation for partial derivatives. We develop the algorithm of the analytical and numerical solutions of boundary value problem for orthotropic rectangular prism. Solution of boundary value problems is reduced to minimize a generalized quadratic form.
Natural convection in horizontal layers with lateral heating at various Rayleigh and Prandtl numbers
Authors: Fedyushkin A I
Published: September 2020

The paper presents the results of numerical solution of the problem of thermal convection of an incompressible liquid in a horizontally elongated layer with lateral heat supply. In this paper the influence of Rayleigh and Prandtl numbers of boundary conditions on the flow structure and on the existence of counter-flows are considered. It is also shown that for laminar convection modes, flows with Prandtl numbers less than 0.01 differ qualitatively from the flow of a liquid with a zero Prandtl number, so the approximation of the zero value of the Prandtl number may not always be correct.
Influence of the nozzle shape on sound generation in a jet-driven Helmholtz oscillator
Authors: Abdrashitov A A , Marfin E A , Plakhova E A
Published: September 2020

The excitation of pressure fluctuations by an air jet in the model of a Helmholtz oscillator, consisting of a cylindrical chamber with a nozzle in the front cover and an outlet opening in the rear one was studied. The influence of the shape of the nozzle in combination with the length of the chamber and the diameter of the outlet opening was considered. The amplitude-frequency spectra when changing the configuration of the oscillator and the Reynolds number in the allowable range was analyzed. The formation of the reverse flow area in a cylindrical nozzle and its influence on the intensity of the interaction of the jet with the flooded chamber volume are considered. The advantage of a nozzle with a profiled inlet providing a continuous flow in the nozzle and a top-hat profile of velocity at the nozzle exit are determined. The jet-driven Helmholtz oscillator can be used as a downhole emitter for intensifying oil production.
Stabilization of a diffusion flame by a non-stationary electric field
Authors: Tupikin A V , Zamashchikov V V
Published: September 2020

The work is devoted to the study of stabilization of a diffusion torch by an electric field with a time-varying field line configuration. The stability of combustion was studied using this method of stabilization of the flame, namely the position of the ignition points in the presence and absence of an electric field. The experiments proved that the stabilizing effect of an electric field with a time-varying field line configuration is observed when the torch is stabilized near and above the plane of the electrodes. When the direction of electric forces coincides with the direction of the fuel jet, the effect of the field will strengthen the fluctuation of flame.
Numerical study of gas-dynamic and condensation processes in an ejector device used to purify gas-air emissions
Authors: Nazarov V S , Ivanov I E , Kryukov I A
Published: September 2020

The article presents a numerical study of vapor condensation appearing in an ejector. The ejector is a part of a device developed by the authors and used to purify air emissions. The article considers condensation of pure water vapor and condensation of vapor in a mixture of vapor and carrier gas. The system of axisymmetric Navier-Stokes equations and the system of moment equations are considered as a mathematical model for describing two-dimensional non-stationary gas-dynamic processes and processes of phase transitions in the device. The general system of equations is numerically solved using the finite volume method.
Investigation of the Stress-Strain State of the Composite Cylindrical Shell with Rectangular Cutouts
Authors: Bakulin V N
Published: September 2020

An algorithm for constructing a model of effective finite elements of natural curvature for the stress-strain analysis of thin composite cylindrical bending shells, including those weakened by rectangular cutouts, is given. The reliability, accuracy, and model efficiency of the considered finite element and the approximations, which it is based on, are shown by comparison with the most commonly used finite elements. Experimental data for a composite shell with rectangular cutouts are obtained and shown. The computation results obtained using the considered finite element are compared with the experimental data for a composite shell with rectangular cutouts.
Analytical Review of Account Methods and Experimental Approaches to Stress-Strain State Investigation of Structurally-Anisotropic Aircraft Panels Made from Composite Materials
Authors: Gavva L M , Firsanov V V
Published: September 2020

Abstract The different approaches were analyzed to investigate the stress-strain state problems of structurally-anisotropic panels made from composite materials. The classification of mathematical models, analytical methods of calculations, numerical methods of calculations, testing results are presented in this review. New mathematical model relations for the stress-strain state investigation of structurally-anisotropic panels made of composite materials are presented. The primary scientific novelty is the further development of the theory of thin-walled elastic ribs related to the contact problem for the skin and the rib with an improved rib model. A promising area of research is the design of composite aircraft structures in the field of production technologies. We consider the residual thermal stresses and the preliminary tension of the reinforcing fibers with respect to the panel production technology. The stress-strain state problem results in the boundary value problem when solving for the eighth order partial derivative equation in the rectangular field. A computer program package is developed in MATLAB. The computer program package has been utilized for multi-criteria optimization of the design of structurally-anisotropic aircraft composite panels. The results of testing series are presented as the verification of the proposed mathematical model.
Dynamics of initiation of the pseudoshock combustion mode in a constant cross section channel
Authors: Tupikin A V , Tretyakov P K , Kuranov A L , Abashev V M
Published: September 2020

The results of a study on the dynamics of initiation of a pseudo-shock combustion mode in a channel of constant cross section under pulsed action on the flow are presented. Various conditions are considered (kerosene flow rate, change in channel length and working gas in control pulses). Pulsating combustion mode is implemented. It is shown that the reduction of the length of the constant section leads to a decrease in combustion stability. When applying control pulses, two scenarios of the development of disturbances can be implemented: with intensification of combustion and the formation of wave structures, or with attenuation without intensification of combustion. In case of combustion, the motion of the disturbance along the channel can conditionally be divided into two stages: 0 <t <4 ms and t > 4 ms. The duration of the first stage can be interpreted as a delay in the ignition of kerosene; in the second stage, the perturbation velocity relative to the channel walls is almost constant. The use of kerosene (synthesis gas) conversion products in pulses accelerates the transition from diffusion to pseudo-shock combustion, and the rate of disturbance propagation increases by about 2 times.
Low-Power Ion Thrusters. State of Development at Research Institute of Applied Mechanics and Electrodynamics, MAI
Authors: Akhmetzhanov R V , Bogatyi A V , Kashirin D A , Obukhov V A , Popov G A , Svotina V V , Khartov S A
Published: September 2020

This article describes the activities carried out by RIAME MAI in the field of low-power ion thrusters in 2010-2020. The results of study of a laboratory model of low power RIT using a different shape of GDC are presented. The results of work on creating an experimental model of such RIT with elements of the propulsion system are shown. The article also presents the research on the process of erosion of the accelerating electrode of the RIT - a critical element of the thruster design from the point of view of the lifetime.
Effect of radiation on the contact thermal resistance in vacuum
Authors: Ezhov A D , Bykov L V , Reznik S V
Published: September 2020

The solution to most of the problems of ensuring the operating characteristics of units and assemblies of complex technical objects in a wide range of changes in temperature and mechanical loads is associated with ensuring the conditions of contacting surfaces, i.e. with the solution of the contact problem of determining the thermal and strength state of the connection of parts. This problem is also relevant to objects operated in space in a vacuum, where heat transfer between parts can occur only in contact spots (areas of direct contact of surfaces) due to thermal conductivity or due to radiation in places where there is no direct contact. Obviously, in this case, the total contact thermal resistance consists of the composition of these types of heat transfer, and largely depends on the profile and roughness of the contacting surfaces. An assessment of the effect of reemission on the value of contact thermal resistance when the temperature in the contact zone varies from 200 °C to 800 °C under vacuum conditions can allow a much more accurate prediction of the operational characteristics of the contact pair. In this paper, we compare the effect of reemission on the value of contact thermal resistance under various mechanical stresses.
Applying of the heat wave equation in the study of the movement of an aggressive environment front
Authors: Kuznetsov Evgenii B , Leonov Sergey S
Published: September 2020

The article investigates the problem of diffusion of an aggressive environment into a material of construction. This problem is especially relevant when the penetration of an aggressive environment into the structural elements of nuclear installations is investigated. For modeling the diffusion process, we use a hyperbolic wave equation describing the motion of a heat wave. Using the Fourier method, an analytical solution is obtained. An example illustrates the solution of the problem of hydrogen diffusion into a long, thin rectangular cross-section iron rod.
Numerical solving of initial value problems for ordinary differential equations with internal limiting singular points
Authors: Ivannikov A I , Kuznetsov E B , Leonov S S
Published: September 2020

In the present paper, we investigate the numerical methods for solving initial value problems for systems of nonlinear ordinary differential equations with several limiting singular points. Similar tasks have great practical importance in such areas as hydrodynamics, chemical kinetics, combustion theory, computational geometry, and nuclear reactors. However, the exact solution may be constructed to nonlinear initial value problems only in exceptional cases. Numerical methods also do not give the desired result. Explicit methods make it possible to obtain a solution only if there is one limiting singular point on the right boundary of the considered interval of the argument change. Implicit methods also have usage restrictions. They consist of the difficulty or impossibility of overcoming the internal limiting singular points. For solving the considered class of problems, the paper proposes to use the method of solution continuation, which allows passing any limiting singular points effectively. Features of the application of various numerical methods are shown by solving one test initial value problem. The reliability of the obtained numerical results is confirmed by comparison with the finding analytical solution of the considered test problem.
Experimental investigation of the thermal loads upon electrodynamic modification of supersonic flow around axisymmetrical body
Authors: Popov P A , Monakhov N A , Kotov M A , Poniaev S A
Published: September 2020

The results of experimental studies of the magnetohydrodynamic (MHD) effect on the flow around an axisymmetric model of a supersonic nitrogen stream are presented. The magnetic field was created by a solenoid located on the cylindrical part of the model under the influence of a pulsed electric current flowing through the solenoid. A pulsed gas discharge was ignited on the conical surface of the model, acquiring rotation in the solenoidal magnetic field around the model axis. The effect of the magnetic field on the gas-dynamic structure of the flow near the model and the heat flux to its surface were investigated. In the experiments, schlieren pictures,fast photographic scans of the discharge glow were recorded, and heat flux was measured. The effect of a magnetic field on the gasdynamic structure of the flow near the model and the heat load to its surface were found. Also, the dependence of MHD effects on the polarity of external voltage source connecting was found.
Ultradeep Sequencing Analysis of Paroxysmal Nocturnal Hemoglobinuria Clones Detected by Flow Cytometry:PIGMutation in Small PNH Clones
Authors: Jeong Dajeong , Park Hee Sue , Kim Sung-Min , Im Kyongok , Yun Jiwon , Lee Young Eun , Ryu Sohee , Ahn Yong-Oon , Yoon Sung-Soo , Lee Dong Soon
Published: September 2020

Objectives

We aimed to determine whether small paroxysmal nocturnal hemoglobinuria (PNH) clones detected by flow cytometry (FCM) harbor PIG gene mutations with quantitative correlation.

Methods

We analyzed 89 specimens from 63 patients whose PNH clone size was ≥0.1% by FCM. We performed ultradeep sequencing for the PIGA, PIGM, PIGT, and PIGX genes in these specimens.

Results

A strong positive correlation between PNH clone size by FCM and variant allele frequency (VAF) of PIG gene mutation was identified (RBCs: r = 0.77, P < .001; granulocytes: r = 0.68, P < .001). Granulocyte clone size of 2.5% or greater and RBCs 0.4% or greater by FCM always harbored PIG gene mutations. Meanwhile, in patients with clone sizes of less than 2.5% in granulocytes or less than 0.4% in RBCs, PIG gene mutations were present in only 15.9% and 12.2% of cases, respectively. In addition, there was not a statistically significant positive correlation between FCM clone size and VAF or the presence or absence of a PIG mutation.

Conclusions

Our results showed that in small PNH clones PIG gene mutations were present in only a small portion without significant correlation to VAF or the presence or absence of a PIG mutation.
Transnational corporations, financialization and community development in West African cocoa
Authors: Amanor Kojo S
Published: September 2020

This article examines the role of financial capital in the cocoa industry of Côte d’Ivoire and Ghana. It argues that the processes of structural adjustment in the 1980s and 1990s brought two important elements into play. Firstly, transnational corporations taking advantage of the opening of global markets to gain control over the cocoa sector, and secondly, financial institutions promoting ‘country platforms’ that encouraged public–private partnerships to mobilize foreign investments and define development objectives. This has led to a distinct pattern of investment, which is intimately connected with governance reforms underpinned by a diverse set of public and private alliances at different levels. The article traces these alliances which have given rise to community development programmes. However, these programmes are underpinned by a drive towards greater intensification of production through the use of inputs supported by credit, which threatens to entangle farmers in debt and lock them into the poverty inherent in the cocoa industry.
Characteristics of patients with coexisting DNAJB9-associated fibrillary glomerulonephritis and IgA nephropathy
Authors: Said Samar M , Rocha Alejandro Best , Valeri Anthony M , Sandid Mohamad , Ray Anhisekh Sinha , Fidler Mary E , Alexander Mariam Priya , Larsen Christopher P , Nasr Samih H
Published: September 2020

Background

Coexistence of fibrillary glomerulonephritis (FGN) and immunoglobulin A (IgA) nephropathy (IgAN) in the same kidney biopsy (FGN–IgAN) is rare, and the clinicopathologic characteristics and outcome of this dual glomerulopathy are unknown.

Methods

In this study, 20 patients with FGN–IgAN were studied and their characteristics were compared with 40 FGN and 40 IgAN control patients.

Results

Concurrent IgAN was present in 1.8% of 847 consecutive FGN cases and was the second most common concurrent glomerulopathy after diabetic nephropathy. FGN–IgAN patients were overwhelmingly White (94%) and contrary to FGN patients were predominantly (60%) males. Compared with IgAN patients, FGN–IgAN patients were older, had higher proteinuria, a higher incidence of renal insufficiency, and a lower incidence of microhematuria and gross hematuria at diagnosis. Six (30%) patients had malignancy, autoimmune disease or hepatitis C infection, but none had a secondary cause of IgAN or clinical features of Henoch–Schonlein purpura. Histologically, all cases exhibited smudgy glomerular staining for immunoglobulin G and DnaJ homolog subfamily B member 9 (DNAJB9) with corresponding fibrillary deposits and granular mesangial staining for IgA with corresponding mesangial granular electron-dense deposits. On follow-up (median 27 months), 10 of 18 (56%) FGN–IgAN patients progressed to end-stage kidney disease (ESKD), including 5 who subsequently died. Serum creatinine at diagnosis was a poor predictor of renal survival. The proportion of patients reaching ESKD or died was higher in FGN–IgAN than in IgAN. The median Kaplan–Meier ESKD-free survival time was 44 months for FGN–IgAN, which was shorter than IgAN (unable to compute, P = 0.013) and FGN (107 months, P = 0.048).

Conclusions

FGN–IgAN is very rare, with clinical presentation and demographics closer to FGN than IgAN. Prognosis is guarded with a median renal survival of 3.6 years. The diagnosis of this dual glomerulopathy requires careful evaluation of immunofluorescence findings, and electron microscopy or DNAJB9 immunohistochemistry.
Current use and safety of novel oral anticoagulants in adults with congenital heart disease: results of a nationwide analysis including more than 44 000 patients
Authors: Freisinger Eva , Gerß Joachim , Makowski Lena , Marschall Ursula , Reinecke Holger , Baumgartner Helmut , Koeppe Jeanette , Diller Gerhard-Paul
Published: September 2020

Aims 

To evaluate the use of novel oral anticoagulants (NOACs) compared with vitamin K antagonists (VKAs) in adult congenital heart disease (ACHD) and assess outcome in a nationwide analysis.

Methods and results 

Using data from one of Germany’s largest Health Insurers, all ACHD patients treated with VKAs or NOACs were identified and changes in prescription patterns were assessed. Furthermore, the association between anticoagulation regimen and complications including mortality was studied. Between 2005 and 2018, the use of oral anticoagulants in ACHD increased from 6.3% to 12.4%. Since NOACs became available their utilization increased constantly, accounting for 45% of prescribed anticoagulants in ACHD in 2018. Adult congenital heart disease patients on NOACs had higher thromboembolic (3.8% vs. 2.8%), MACE (7.8% vs. 6.0%), bleeding rates (11.7% vs. 9.0%), and all-cause mortality (4.0% vs. 2.8%; all P < 0.05) after 1 year of therapy compared with VKAs. After comprehensive adjustment for patient characteristics, NOACs were still associated with increased risk of MACE (hazard rate—HR 1.22; 95% CI 1.09–1.36) and increased all-cause mortality (HR 1.43; 95% CI 1.24–1.65; both P < 0.001), but also bleeding (HR 1.16; 95% CI 1.04–1.29; P = 0.007) during long-term follow-up.

Conclusion 

Despite the lack of prospective studies in ACHD, NOACs are increasingly replacing VKAs and now account for almost half of all oral anticoagulant prescriptions. Particularly, NOACs were associated with excess long-term risk of MACE, and mortality in this nationwide analysis, emphasizing the need for prospective studies before solid recommendations for their use in ACHD can be provided.
Trends in adolescent drinking across 39 high-income countries: exploring the timing and magnitude of decline
Authors: Vashishtha Rakhi , Pennay Amy , Dietze Paul , Marzan Melvin Barrientos , Room Robin , Livingston Michael
Published: September 2020

Background

Evidence suggests adolescent alcohol consumption has declined since the turn of the millennium in almost all high-income countries. However, differences in the timing and magnitude of the decline have not been explored across countries.

Methods

We examined trends in adolescent past month or monthly alcohol consumption prevalence from cross-national or national survey reports for 39 countries and four US territories. For each country, we calculated the magnitude of the decline in youth drinking as the relative change in prevalence from the peak year to the most recent year available. Heat maps were utilized to present the timing and magnitudes of these declines.

Results

The timing and extent of youth drinking declines have varied markedly across countries. The decline began in the USA before 1999, followed by Northern European countries in the early 2000s; Western Europe and Australasia in the mid-2000s. The steepest declines were found for Northern Europe and the UK, and the shallowest declines were observed in Eastern and Southern European countries.

Conclusions

Previous analyses of the decline in adolescent drinking have emphasized the wide reach of the changes and their near-coincidence in time. Our analysis points to the other side of the picture that there were limits to the wide reach, and that there was considerable variation in timing. These findings suggest that as well as broader explanations that stretch across countries, efforts to explain recent trends in adolescent drinking should also consider factors specific to countries and regions.
Loose Coordination or Ideological Contestation? Transnational Party Activities of German Political Parties on the EU Military Operation EUNAVFOR Med
Authors: Groen Afke
Published: September 2020

This article examines cross-national coordination on foreign and security policy among political parties of the same family. Drawing on resource dependence theory, it presents a case study of German political parties and their transnational activities on the controversial EU military operation to combat human trafficking in the Mediterranean Sea, EU Naval Force Mediterranean. The article finds evidence for transnational information exchange and coordination among the opposition parties, radical left and the greens, but less so among the government party, social democrats. The degree of transnational party activities can be understood by not only the extent to which parties share a common view in the first place but also the different resource needs of the government and opposition parties.
Adult Children’s Daily Experiences With Parental Advice: The Importance of Life Problems and Relationship Quality
Authors: Wang Haowei , Kim Kyungmin , Burr Jeffrey A , Birditt Kira S , Fingerman Karen L
Published: September 2020

Objectives

Parents often provide advice to their adult children during their everyday interactions. This study investigated young adult children’s daily experiences with parental advice in U.S. families. Specifically, the study examined how receiving advice and evaluations of parental advice were associated with children’s life problems, parent–child relationship quality, and daily mood.

Methods

Young adult children (aged 18–30 years; participant N = 152) reported whether they received any advice and perceived any unwanted advice from each parent (parent N = 235) for 7 days using a daily diary design (participant-day N = 948). Adult children also reported their positive and negative mood on each interview day.

Results

Results from multilevel models revealed that adult children who reported a more positive relationship with their parents were more likely to receive advice from the parent, whereas adult children who had a more strained relationship with their parents were more likely to perceive advice from the parent as unwanted. Receiving advice from the mother was associated with increased positive mood, whereas unwanted advice from any parent was associated with increased negative mood. Furthermore, the link between unwanted advice and negative mood varied by children’s life problems and parent–child relationship quality.

Discussion

Indeed, parental advice is not “the more the better,” especially when the advice is unsolicited. This study highlights the importance of perceptions of family support for emerging adults’ well-being.
Benchmarking wave equation solvers using interface conditions: the case of porous media
Authors: Peng Haorui , Sripanich Yanadet , Vasconcelos Ivan , Trampert Jeannot
Published: September 2020

The correct implementation of the continuity conditions between different media is fundamental for the accuracy of any wave equation solver used in applications from seismic exploration to global seismology. Ideally, we would like to benchmark a code against an analytical Green’s function. The latter, however, is rarely available for more complex media. Here, we provide a general framework through which wave equation solvers can be benchmarked by comparing plane wave simulations to transmission/reflection (R/T) coefficients from plane-wave analysis with exact boundary conditions (BCs). We show that this works well for a large range of incidence angles, but requires a lot of computational resources to simulate the plane waves. We further show that the accuracy of a numerical Green’s function resulting from a point-source spherical-wave simulation can also be used for benchmarking. The data processing in that case is more involved than for the plane wave simulations and appears to be sufficiently accurate only below critical angles. Our approach applies to any wave equation solver, but we chose the poroelastic wave equation for illustration, mainly due to the difficulty of benchmarking poroelastic solvers, but also due to the growing interest in imaging in poroelastic media. Although we only use 2-D examples, our exact R/T approach can be extended to 3-D and various cases with different interface configurations in arbitrarily complex media, incorporating, for example, anisotropy, viscoelasticity, double porosities, partial saturation, two-phase fluids, the Biot/squirt flow and so on.