bluuebunny/crossref_metadata_2025_split huggingface dataset:
Bee colony health indicators: synthesis and future directions.
Authors: Requier F. 
Published: December 2019

Abstract

The western honey bee
Apis melifera
plays an important role in human well-being by producing honey, sustaining populations of wild plants and supporting human-dependant crop production. Unfortunately, abnormal high-mortality rates of colonies have been revealed all over the world. This paper reviews the stress factors that are likely involved in the cause of honey bee poor health, the mechanisms underlying bee health and survival and the different early warning indicators of bee colony mortality. Honey bee colonies can be assimilated to a complex system for which survival depends on its individual quality, its adaptive capacity and its threshold of resilience to pressures. Many stress factors are likely involved, by interaction, in the cause of honey bee colony mortality. Three main groups of stressors are highlighted to affect the colony survival, including (i) environmental pressures such as lack of flowers and pesticide exposure, (ii) biotic pressures such as parasites and pathogens and (iii) beekeeping management such as the use of chemical treatments. Routine monitoring of colonies provides robust approaches to assess the health status of honey bees. By tracking specific colony parameters such as queen performance, colony dynamics, in-hive products and the prevalence of pathogens, beekeepers can establish a health status of the colony. By comparing this field-based health status with model-based predictions, a new area is emerging towards the detection of early warning indicators of colony mortality.
Darkness of two-mode squeezed light in Λ-type atomic system
Authors: Moiseev E S , Tashchilina Arina , Moiseev S A , Lvovsky A I 
Published: December 2019

Abstract
We show that, under certain circumstances, an optical field in a two-mode squeezed vacuum (TMSV) state can propagate through a lossy atomic medium without degradation or evolution. Moreover, the losses give rise to that state when a different state is initially injected into the medium. Such a situation emerges in a Λ-type atomic system, in which both optical transitions are driven by strong laser fields that are two-photon resonant with the respective signal modes. Then the interactions of the two signal modes with the ground-state atomic coherence interfere destructively, thereby ensuring the preservation of the TMSV with a particular squeezing parameter. This mechanism permits unified interpretation of recent experimental results and predicts new phenomena.
An experimental study of the propagation of a shock wave in a granular medium
Authors: Alyanov A V , Kazanin I V , Zinoviev V N , Vereshchagin A S , Fomin V M 
Published: December 2019

Abstract
In this work, experimental study of propagation shock waves and pressure-waves in granular medium was performed. As a granular medium are used hollow glass microspheres and composite sorbent based on them. The special experimental setup was prepared, which uses the principle of a shock tube. The setup includes a high pressure section and low pressure section with stepwise change of its internal diameter. The pressure graphics were obtained for the various tube sections for different media. The tube filling time and pressure wave velocity in the medium were estimated.
Gas heat exchange at inhomogeneous combustion of solid porous media
Authors: Amosova E V , Kuznetsov K S 
Published: December 2019

Abstract
The authors suggest using a numerical method based upon the finite element analysis of the equations of continuous inhomogeneous media mechanics to describe thermophysical properties of transient motions of viscous gas through porous media with chemical changes and phase transitions in a solid phase. The model takes into account heat exchange between a solid frame and gas, changes in the phase volume and mass at interaction, the presence of oxidant diffusion. The software developed in FreeFem++ allows clear and vivid studying the process of gas combustion in solid porous medium with inhomogeneous combustion source at forced filtration in the course of time as well as modeling and analyzing a real experiment.
Droplet breakup in shock waves at moderate values of the Weber number
Authors: Boiko V M , Poplavski S V 
Published: December 2019

Abstract
The object of this study was the physical mechanisms of aerodynamic fragmentation of droplets of low-viscosity liquids in shock waves in the region of existence of the shear breakup modes. New experimental data were obtained on the time induction of the droplets breakup depending on the gas flow velocity in the poorly studied range of Weber numbers We = 100 ÷ 2200.
Model of deformation of a liquid drop of zirconium dioxide after its collision with a steel porous surface
Authors: Bublik V V , Cherepanov A N 
Published: December 2019

Abstract
Based on the integral laws of conservation of mass and energy, a mathematical numerical-analytical model of the deformation of a continuous liquid-metal drop after its collision with a flat porous surface is constructed. The model takes into account the capillary and adhesive properties of the melt, the processes of cooling a liquid drop until it solidifies. Numerical calculations are performed for the model case of collision of a continuous liquid drop of zirconia with a porous steel substrate.
Determining the law of ice deformation
Authors: Buznik Vyacheslav , Golushko Sergey , Amelina Evgeniya , Belyaev Vasily , Bryndin Luka , Gorynin Arseniy , Shapeev Vasily 
Published: December 2019

Abstract
A mathematical model of nonlinear deformation of ice samples from distilled water is implemented. An algorithm for numerical solution of corresponding boundary-value problem is proposed and realized. Results of the numerical modeling have been compared to experimental data on the three-point bending of ice beams.
Influence of surface active agent on the size of metal powder particles during their ball milling in a planetary mill
Authors: Chesnokov A E , Smirnov A V , Vidyuk T M 
Published: December 2019

Abstract
The paper presents the results of a study of the influence of surface active agent during the ball milling of metal powders in a planetary mill. It is shown that the mass fraction of the surface active agent in the powder mixture under study affects the size of the particles being treated, depending on the time of processing. The particle size distribution, the specific surface area were determined, and the surface morphology of the initial and ball milled particles was studied.
Impact of the rate of input of specific energy on the ball milling of aluminium in a planetary mill
Authors: Chesnokov A E , Smirnov A V , Vidyuk T M 
Published: December 2019

Abstract
In the present study, the effect of the rate of the input of comparable amounts of energy into the material being processed on the particle size and on the value of specific surface area of the particles was analysed. It was shown that, irrespective of the rate of the energy input into the material, the resultant particles have similar characteristics, including their size and shape, and the value of the specific surface area. A more intense action exerted by the grinding bodies on the particles in the material being processed is accompanied by a sharp increase of temperature throughout the entire system. The heated particles plasticize, thus undergoing to a rolling-type granulation process.
Modeling the process of river bed bottom erosion in the area of the underwater pipelines location
Authors: Degtyarev V V , Garmakova M E , Shumkova M N , Chebotnikov A V 
Published: December 2019

Abstract
This paper deals with the modeling of flows and transport of sand particles during erosion of pipelines. The results of an experimental study of velocity fields and numerical CFD modeling in a three-dimensional transient formulation on the basis of Reynolds averaged Navier-Stokes equations in the ANSYS software package are presented. Modeling was carried out with different arrangement of pipelines, simulating cylinders, on a sandy bottom. The influence of the number of cylinders on the process of bottom soil reformation is analyzed.
Direct numerical simulation of viscous incompressible flow with spherical particles in the flat channel
Authors: Esipov D V , Lapin V N , Kuranakov D S , Chirkov D V 
Published: December 2019

Abstract
The paper deals with numerical simulation of 3D fluid flow with relatively large spherical particles in the flat channel. The simulation is performed using the previously developed SIMPLE based immersed boundary method. The collision model, describing particle-particle and particle-wall collisions, complements the numerical method. This model prevents particle overlapping and takes into account the complicated fluid flow in the space between the particles. The computed flow rates decrease significantly with increasing the particle concentration. It is shown that the value of the particle diameter has a small influence on the flow rate. The flow rate can be approximated using the value of effective viscosity computed by Maron – Peirce formula with the use of extremely high packing concentration. Particles are moving faster than the mixture, and the difference increases with increasing concentration.
Numerical investigation of wave propagation in high-permeable cylindrical waveguide in porous medium
Authors: Gubaidullin A A , Boldyreva O Yu , Dudko D N 
Published: December 2019

Abstract
The features of waves propagating in a highly permeable cylindrical waveguide in a porous medium are numerically investigated. The influence of the ratio of permeability inside the cavity and the surrounding porous medium, as well as the signal frequency on the evolution of the pressure wave inside the cavity is studied. On the basis of the calculated data, estimates of the velocity and attenuation of the signal during its propagation in the waveguide in a wide frequency range are obtained. It is shown that with the increase in the waveguide permeability, the propagation velocity increases and the attenuation of waves decreases, the depth of penetration of perturbations into the surrounding space decreases. Increasing the frequency of the initial signal leads to an increase in the velocity and attenuation of the pulse. A comparison is made with the case of wave propagation in a liquid-filled cylindrical cavity in a porous medium. The results of the study can be used in the interpretation of well logging data.
Calculation of rocks permeability based on periodic models of porous media
Authors: Igoshin D E , Legostaev D Yu 
Published: December 2019

Abstract
The paper proposes a method for calculating rock permeability based on periodic cubic models of porous media, taking into account the particle size distribution of the samples. Conditional permeability is calculated for each fraction. The permeability of the sample depends on the relative position of the fractions and can be calculated as the weighted average (arithmetic, geometric or harmonic). Next, an optimization problem is solved, which allows one to choose the “weight” of a particular method of averaging permeability over fractions inside the sample for all samples of the selected formation. Results were obtained for several formations from different fields.
Mathematical model of the submerged jet for the cases of man-made spills
Authors: Kildibaeva S R , Gimaltdinov I K , Kildibaeva G R 
Published: December 2019

Abstract
The paper considers a mathematical model of the spread of a multiphase submerged jet, the flow of which is associated with a well damage during the development of a field or pipeline during oil transport. The jet consists of oil droplets and gas bubbles, as well as water involved into the jet. The case is considered when the environmental conditions correspond to the conditions of a stable hydrate existence, because a hydrate shell begins to form and the gas bubble turns into a hydrate on the surface of the bubbles. The integral Lagrangian control volume method is used to describe the jet spread process. The thermo-physical characteristics of a multiphase submerged jet, depending on the vertical coordinate, as well as the trajectory of the jet, are obtained.
Numerical simulation of fluid flow in a saturated fractured porous media based on the linear poroelasticity model
Authors: Legostaev D Yu , Botalov A Yu , Rodionov S P 
Published: December 2019

Abstract
Field development processes change the stress-strain state of the formation, which can especially affect on the state of fractured reservoir. In this paper, the coupled flow and geomechanics model was used to simulate a fractured-porous reservoir. To describe fractures in the fluid flow problem the discrete fracture model was used; the fracture was considered as an internal boundary for the geomechanics problem. The control volume method, which is widely used in computational fluid dynamics, was used for both flow and mechanics problems. Based on the developed coupled flow and geomechanics model, simulations of an fractured poroelastic system was carried out.
Application of continuous symmetry groups for numerical solutions of two-phase filtration problems
Authors: Markov Pavel 
Published: December 2019

Abstract
The method of numerical solution calculations for difference schemes on the basis of continuous symmetry groups has been presented for the two-phase flow equation. This method gives an opportunity to calculate numerical solutions using transformations of a symmetry group and known particular numerical solutions what allows to achieve an acceleration of serial numerical calculations by several orders. The families of invariant difference schemes have been obtained for one of generalized Buckley-Leverett equations - the Rapoport-Leas equation. A particular nonlinear equation of multiphase flow in fractured porous media with certain coefficients from the mentioned families is analyzed numerically by the presented method.
Simulation of the deposition of aerosol droplets in a person’s bronchial tree
Authors: Medvedev A E , Gafurova P S 
Published: December 2019

Abstract
The work is devoted to the mathematical construction of the human bronchial tree, calculating the flow of gas in the lungs and modelling the deposition of drops of medicinal aerosols in the human bronchial tree. Analytically built a symmetrical human bronchial tree. To calculate the flow of gas in the lungs and the deposition of aerosols, the method of phasing out the flow in one branch of the bronchial tree is used. Three-dimensional numerical calculations of air flow and aerosol droplets in human lungs were carried out. It is shown that the number of past drops depends (except for the flow, size of drops) on the duration of inhalation.
Effect of the structure of skeleton models of cellular materials on the drag of a cylinder with a frontal gas-permeable insert in a supersonic flow
Authors: Mironov S G , Kirilovskiy S V , Militsina T S , Poplavskaya T V , Tsyryulnikov I S , Valiullin I R 
Published: December 2019

Abstract
The paper presents the results of the numerical simulation of the supersonic (M∞ = 7) flow around the cylinder with the front gas-permeable porous insert at different angles of attack. The numerical simulation involves the comparative analysis of a number of skeleton models of high-porous cellular materials of the front insert: from the set of coaxial rings of different diameters, and the set of hollow spheres with different spatial resolution. The calculated data of the drag coefficient have been compared with the wind tunnel experiment results.
On the issue of the solutions existence of the problem of gas hydrate dissociation in a porous medium with the formation of an extended region of phase transitions
Authors: Musakaev N G , Khasanov M K 
Published: December 2019

Abstract
Mathematical model of the gas hydrate dissociation in a porous medium with the formation of an extended region of phase transitions is proposed. In a rectilinear-parallel approximation self-similar solutions are constructed that describe the distribution of pressure, temperature, and hydrate saturation in a reservoir. Based on the obtained solutions analysis it was proved that for the problem of injecting warm gas into a hydrate saturated reservoir with piezoconductivity coefficient exceeds the thermal diffusivity coefficient, there are no solutions with an extended region of phase transitions. The existence of such solutions is possible during gas production from a gas hydrate reservoir due to a decrease in pressure at the extraction point.
Cutting transport simulation in a horizontal borehole near tool joints
Authors: Orlik E , Ignatenko Y , Bocharov O 
Published: December 2019

Abstract
In the presented study, we investigated the influence of cuttings transport in a channel with variable cross-section area to determine the pressure drop and obtain preliminary data on tool joint effect on solids deposition. The influence of boundary conditions at the channel’s inlet on flow regimes was analysed. The average particle concentration over the cross-section significantly reduced due to increasing the velocity in the narrowing area on the tool joint. Behind the tool joint, particles deposition appeared due to the reverse flow, which manifested itself as a local maximum in concentration distribution along the channel. The impact of a tool joint on the pressure drop in a single-phase flow has been more pronounced if compared to one in a two-phase flow at the given conditions.
Models of heterogeneous medium in medicine
Authors: Pen’kovskiy V I , Korsakova N K 
Published: December 2019

Abstract
A review of models of the blood circulation in the tissues of the human brain and lower extremities is presented. The models take into account the well-known laws of physiology and theoretical mechanics. Mathematical models are based on the representation of organ tissues as a heterogeneous continuous medium consisting of three interpenetrating continua: living cells, and circulating arterial and venous blood. The results of numerical calculations of boundary value problems of the pulse blood flow in the brain of a healthy person and cases of pathologies such as arteriovenous malformation and embolism are presented. The distribution of blood pressure in the lower extremities is studied under the action of gravity and other overloads.
Studying the process of powder transportation during laser cladding with a coaxial nozzle
Authors: Polyanskiy T A , Zaitsev A V , Ermolaev G V 
Published: December 2019

Abstract
Results of experiments and numerical modeling of gas-powder flow for laser cladding are presented. Numerical simulation is based on solving Navier-Stokes equations with Lagrange approach for particle. The main attention is paid to the process of interaction between powder particles and nozzle walls. Simple particle-wall interaction model was suggested and verified with experiments for gas-powder jet formed in the long tubes with different diameters. The model was used for simulation of powder transport in the coaxial nozzle for laser cladding.
On the near wake structure of a supersonic coaxial gas-liquid jet
Authors: Poplavski S V , Nesterov A Yu 
Published: December 2019

Abstract
The work is devoted to a complex experimental study of the near wake of supersonic coaxial gas-liquid jets with a high concentration of the dispersed phase. At the various liquid flow rates, wave structure of a gas phase was visualized, droplet velocity profiles were obtained by the LDA method, and the spray concentration was measured. The effect of the liquid phase on the supersonic underexpanded jet was studied, in particular, a change in the general wave structure, Mach disk transformation, etc. A gas velocity profile was obtained in a two-phase core of a gas-liquid jet by the method of droplet velocity profile correction taking into account their velocity relaxation.
Numerical simulation of nucleation and solid phase growth in a nanomodified binary alloy
Authors: Shchukin V G , Popov V N 
Published: December 2019

Abstract
A mathematical model of solidification of a binary alloy with eutectic-type phase diagram modified by refractory nanoscale particles as nucleation centers of the crystalline phase is proposed. Thermodynamic processes in the melt and solid phase, heterogeneous nucleation and growth of particles of the main (α) phase of the crystallizing material are described. The crystal phase origin occurs on the surface of nanoscale particles. The volume of the solid phase grown on separate crystallization centers determines the character of the grain structure in the solidified alloy. On the example of a binary alloy based on iron (Fe-C) numerical simulation of melt solidification in a cylindrical casting is carried out. The features of the kinetics of heterogeneous nucleation and crystallization in the melt were considered. It is determined that the undercooling magnitudes, the conditions of nucleation, the rate of crystallization and solidification time vary significantly inside the casting. It is established that as the melt cools, volume-sequential crystallization takes place. The area with the finest structure of the solidified metal is located near the wall of the mold.
Numerical simulation of mono-disperse gravity-driven granular flow around a wedge using two-fluid model
Authors: Shoev Georgy 
Published: December 2019

Abstract
The numerical simulation of glass beads granular flow around a wedge located in a rectangular channel is performed by the Two-Fluid Model (i.e. the Euler-Euler approach) aiming to make a comparison between the numerical and the available experimental data. The channel is tilted against the horizon making the glass beads fall under the action of the gravity force. The numerical simulation shows the glass beads structure that resembles a bow shock wave around the wedge. The computed bow shock stand-off distance is compared to the data extracted from the experimental results. The details of the comparison between the numerical and the experimental data are discussed.
Formation of the internal structure of copper particles during their ball milling followed by spheroidization
Authors: Smirnov A V , Chesnokov A E , Vidyuk T M 
Published: December 2019

Abstract
The paper presents the results of a study of the influence of high-energy effects on surface morphology and the formation of the internal structure of copper particles. It is shown that the ball milling of copper powder in a planetary mill leads to the formation of layered agglomerates consisting of many deformed ultrafine particles. It is noted that defects in the form of microcracks and micropores are observed in the volume of the agglomerated particle. Their subsequent treatment in a plasma jet leads to the formation of spherical particles. It is established that during the interaction of the molten material of a particle with distributed gas inclusions throughout the particle’s volume during plasma treatment, local copper oxidation occurs. Copper oxide inclusions of predominantly rounded shape are formed, ranging in size from tens of nanometers to 7 microns, uniformly distributed over the particle volume.