bluuebunny/crossref_metadata_2025_split huggingface dataset:
The traditional approximation of rotation, including the centrifugal acceleration for slightly deformed stars
Authors: Mathis S. , Prat V. 
Published: September 2019

Context. The traditional approximation of rotation (TAR) is a treatment of the dynamical equations of rotating and stably stratified fluids in which the action of the Coriolis acceleration along the direction of the entropy (and chemicals) stratification is neglected, while assuming that the fluid motions are mostly horizontal because of their inhibition in the vertical direction by the buoyancy force. This leads to the neglect of the horizontal projection of the rotation vector in the equations for the dynamics of gravito-inertial waves (GIWs) that become separable, such as in the non-rotating case, while they are not separable in the case in which the full Coriolis acceleration is taken into account. This approximation, first introduced in geophysical fluid dynamics for thin atmospheres and oceans, has been broadly applied in stellar (and planetary) astrophysics to study low-frequency GIWs that have short vertical wavelengths. The appoximation is now being tested thanks to direct 2D oscillation codes, which constrain its domain of validity. The mathematical flexibility of this treatment allows us to explore broad parameter spaces and to perform detailed seismic modelling of stars.
Aims. The TAR treatment is built on the assumptions that the star is spherical (i.e. its centrifugal deformation is neglected) and uniformly rotating while an adiabatic treatment of the dynamics of the waves is adopted. In addition, their induced gravitational potential fluctuations is neglected. However, it has been recently generalised with including the effects of a differential rotation. We aim to carry out a new generalisation that takes into account the centrifugal acceleration in the case of deformed stars that are moderately and uniformly rotating.
Methods. We construct an analytical expansion of the equations for the dynamics of GIWs in a spheroidal coordinates system by assuming the hierarchies of frequencies and amplitudes of the velocity components adopted within TAR in the spherical case.
Results. We derive the complete set of equations that generalises TAR by taking the centrifugal acceleration into account. As in the case of a differentially rotating spherical star, the problem becomes 2D but can be treated analytically if we assume the anelastic and JWKB approximations, which are relevant for low-frequency GIWs. This allows us to derive a generalised Laplace tidal equation for the horizontal eigenfunctions and asymptotic wave periods, which can be used to probe the structure and dynamics of rotating deformed stars thanks to asteroseismology. A first numerical exploration of its eigenvalues and horizontal eigenfunctions shows their variation as a function of the pseudo-radius for different rotation rates and frequencies and the development of avoided crossings.
Koronare Herzkrankheit als Ursache für Beschwerden im
Bereich von BWS und Sternum
Authors: Lackenbauer Wolfgang 
Published: September 2019

ZusammenfassungEine 80-jährige Patientin mit chronischen Schmerzen in der LWS, zusätzlichem
Druck-/Engegefühl im Brustkorb bzw. hinter dem Brustbein sowie Atemlosigkeit vor
allem bei physischer Anstrengung mit gleichzeitig auftretenden Schmerzen in der
BWS zwischen den Schulterblättern wurde zur Physiotherapie überwiesen. Die
Symptome im Bereich Brustkorb/Sternum und der BWS ließen sich weder durch eine
Haltungsänderung noch durch Aktivität/Bewegung der oberen Extremitäten oder der
Wirbelsäule auslösen bzw. reproduzieren.Aufgrund des für koronare Herzkrankheiten typischen Beschwerdebildes wurde die
Patientin zur weiteren fachärztlichen Abklärung überwiesen. Kurz darauf unterzog
sie sich einer 4-fachen Bypass-Operation am Herzen.
Symmetric semigroups with three generators
Authors: Vorob’ev I. S. , Ustinov A. V. 
Published: September 2019

Abstract
In the theory of numerical semigroups the Frobenius problem of finding the largest integer that does not belong to the given semigroup plays an important role. The study of the Frobenius problem suggests distinguishing the class of symmetric semigroups, which have a quite simple structure. The main result in this work is an asymptotic formula describing the growth of the number of symmetric semigroups with three generators.
Bibliography: 18 titles.
Singlet oxygen generation by nanoporous silicon: photoluminescence dynamics in magnetic field
Authors: Aliev Gazi N , Amonkosolpan Jamaree , Wolverson Daniel 
Published: September 2019

AbstractSinglet oxygen generation in porous silicon (PSi) was investigated by a magneto-optical experiment. Photoluminescence (PL) quenching due to an energy transfer (ET) process mediated by an exchange interaction was monitored in the spectral range 1.4–2.5 eV and in a magnetic field of 0–6 Tesla at different levels of oxygen concentration and excitation pump power. When a magnetic field was applied, both PL recovery and, for magnetic fields below 2 Tesla and high concentrations of oxygen, an unusual additional pump power dependent quenching of the PL was observed. A rate equation model describing the behavior of PL from PSi with oxygen adsorbed at cryogenic temperatures in magnetic field was developed. The model has been expanded to cover the ET process as a function of the nanoparticle size.
Mathematical simulation of stress-strain state of loaded rods with account of transverse bending
Authors: Anarova Sh , Ismoilov Sh 
Published: September 2019

Abstract
Mathematical simulation of stress-strain state of loaded rods with account of transverse bending is considered in the paper. The urgency, the correctness of mathematical statement of the problem, the mathematical model, the computational algorithm and the computational experiments of the problem set are given in the paper. Results are presented in a graphical form. The oscillations of spatially loaded rods are shown. The analysis is made in linear and non-linear statements.
Computational methods of minimization of multiple functions
Authors: Kabulov A V , Normatov I H , Ashurov A O 
Published: September 2019

Abstract
The article discusses computational methods for minimizing multivalued functions. The problems of the minimization of combinational circuits are investigated. An effective heuristic method intended to simplify the canonical forms of arbitrary functions was developed. The method allows to reduce the cost necessary to build a combinational circuit. The proofs of the theorem and definitions about the operation of gluing and absorption to DNF of multivalued functions in the class of disjunctive normal forms are privatized. Examples are given for applying the gluing and absorbing operation to DNF Df
, we obtain abbreviated DNF Dl
.
Investigation of the properties of of reactions-diffusion model solutionswithdouble nonlinearity
Authors: Muhamediyeva D K 
Published: September 2019

Abstract
Analyses show that the central place in the mathematical description of the spatial-temporal dynamics of one or several interacting populations take the task of research of interaction of the migration population processes with demographic. Population models that take into account only the demographic processes are well known and fairly well-developed. This assumption is true if modelled area is quite small compared with the mean free path of individuals, or, equivalently, with a radius of individual activity . If this provision violated, in population models must account migration.
Determination of geometric parameters for flexible splines of wave gearing
Authors: Abakumov A N , Zakharova N V 
Published: September 2019

Abstract
The paper considers the influence of a number of flexspline geometric parameters on the stresses acting in it. The influence of the most significant parameters such as the diameter of the flexible spline and the thickness of its rim under the gear rim is considered. As a result of analysis of the flexspline geometric parameters influence on its load capacity, the recommendations are given for assigning the main dimensions of the spline at the stage of design.
Attitude dynamics of nanosatellite with a module on retractable beams
Authors: Aslanov V S , Doroshin A V , Eremenko A V 
Published: September 2019

Abstract
Attitude dynamics of nanosatellites with a module on retractable beams is considered. The movable module is attached to the main body of the nanosatellite with the help of retractable beams of variable length. The attitude control is fulfilling by the beams length changing that translates the position of the mass center and creates the torque from the jet-engine with constant fixation relative the main body. The movable module can represent the multifunctional element, e.g. telescope, radiometer etc. Such control scheme allows to use the functional module as the simple actuator of the control system. So in this case the control don’t need the presence of special executive bodies.
Computer simulation possibilities of dynamic tests of large-scaled mechanical structures
Authors: Doronin S V , Reizmunt E M 
Published: September 2019

Abstract
The work is devoted to the analysis of the computer simulation capabilities of dynamic testing of large-scaled structures when exposed to acoustic noise, sinusoidal and random vibration, linear acceleration, mechanical single and multiple shocks. The simulation results obtained with regard to the regulatory requirements for the test methods for the action of external influencing factors reflect the effect of the main conceptual and technical solutions of the structures on their dynamic behaviour. Computer simulation of dynamic tests allows, on the one hand, to exclude unacceptable dynamic effects due to unsuccessful design decisions, on the other hand, can be considered as an important part of the design conformity assessment with technical requirements.
Analysis of the Striker Stroke Impact on the Hydropneumatic Impact Devices Energy Performance
Authors: Galdin N S , Semenova I A , Galdin V N 
Published: September 2019

Abstract
The study results of the hydropneumatic impact devices striker movement impact on the energy performance during the operating stroke are presented. The energy parameters of the hydropneumatic impact units include power and single impact energy. The mathematical model of the hydropneumatic impact unit operating process is briefly described. The idle stroke, deceleration, operating stroke of the hydropneumatic impact unit striker are characterized. The software for conducting the hydropneumatic impact unit study is developed. The impact devices energy performance depends on the striker velocity at the time of impact, as well as on the striker mass and stroke. Gas pressure in the pneumatic accumulator also influences the energy performance. The striker velocity and single impact energy graphic dependences on the striker stroke and mass, gas pressure in the pneumatic accumulator are represented. The analysis of the obtained dependences is provided. The velocity at the time of the hydropneumatic impact device tool impact on the ground can vary in a wide range from 4.5 to 8 m/s at the stroke of the striker from 50 to 100 mm. It makes possible to use a hydropneumatic impact device as various replacing equipment of road building machines such as excavators.
Consideration of nonlinear properties of new structural materials
Authors: Gelver I S , Kolunin A V , Shudykin A S 
Published: September 2019

Abstract
In recent years, new structural materials (composite and polymer materials, non-ferrous alloys) are widely used in mechanical engineering. For example, in the production of high-pressure vessels, in order to lighten the design, a thin-walled aluminum alloy liner is installed in a strong carbon fiber shell. However, such materials are among the physically nonlinear ones, when, even with minor deformations, there are significant deviations from the Hooke’s law. Therefore, the development of methods to account for this effect and assessment of its impact on the stress-strain state of the design is an actual problem. In this paper, the authors justify the possibility of using the finite element method for nonlinear relationship between stresses and strains. They propose to approximate a real deformation diagram by a cubic parabola. As a result, the calculation data are obtained in the form similar to the linear theory of the finite element method.
Investigation of the influence of the length of the rope suspension of the bridge crane and the length of displacement of the cargo in the controlled sway mode on the time of displacement
Authors: Korytov Mikhail S , Shcherbakov Vitaly S , Titenko Vladimir V 
Published: September 2019

Abstract
The formulas for a complete analytical solution of the problem of moving cargo on a pendulum suspension of constant length along a given trajectory in a plane setting are presented. To set the desired trajectory as a time dependence of the linear horizontal coordinate of the cargo in a limited time interval, two-point Hermite polynomials are used. The field of application of the method is the automatic control of the movement of bridge and gantry cranes, as well as modeling of crane working processes. The application is limited to small angles of deviation of the cargo rope of the bridge crane from the gravitational vertical. The method makes it possible to quickly synthesize the optimal trajectory of the point of cargo suspension movement, which accurately provides the required trajectory of cargo movement. For a series of constant values of the maximum acceleration developed by the point of suspension of the cargo during a single transient process, graphs of the moving time dependences from moving length and cargo rope length are revealed. The functions obtained are not smooth and have a fracture. This makes it impractical to approximate them using the regression equation, due to the high error of the latter. The resulting graphs can be used to determine the time of movement of the cargo depending on the specified length of moving, the length of the cargo rope and the maximum acceleration developed by the drive of the cargo suspension.
Simulation model for the determination of energy losses during vibrations of the working equipment of a earth-moving machine in the transport mode
Authors: Korytov M S , Shcherbakov V S , Titenko V V , Ots D A 
Published: September 2019

Abstract
A simulation model for a earth-moving machine is developed using a motor grader as an example. The model comprises a chassis base frame, a front balancing bridge, rear balancing carts and working equipment – a traction frame with a moldboard. These elements are included in the form of separate moving elements. The simulation model allows the vibrations of the machine units to be explored while it moves along the microrelief of a reference surface, as well as the energy loss due to friction in the suspension elements of the working equipment to be determined. Using this simulation model, the amount of energy accumulated with the help of improved suspension devices for the working equipment of the motor grader can be assessed. This allows for the combination of the vibration damping of the working equipment in the transport mode and the oscillation energy accumulation. The effect of the stiffness and viscous friction coefficients of the hydraulic cylinders for raising and lowering the moldboard with a device for dynamic vibration damping and the accumulation of their energy on the total amount of energy spent on dissipation in the hydraulic components of the working equipment suspension elements is established. The resulting graphical functional dependence allows the optimization of the parameters of the hydraulic, mechanical and electrical parts of the system of the vibration damping and energy storing device to be implemented.
Mechanical action on edges of plastic parts using electrohydraulic effect
Authors: Kovalevsky V F , Skobelev S B , Bezzateeva E G , Bury G G , Poteryaev I K 
Published: September 2019

Abstract
The paper reviews the methods of cleaning plastic parts from flash. The principle of plant operation to obtain L. A. Yutkin electro-hydraulic effect is considered. The design of a pilot plant, as well as replaceable devices used to remove the flash from the edges of plastic parts is presented. The results of experimental studies of the electro-hydraulic effect for deflashing are presented.
Geometrical synthesis of four-bar gear train with related gears
Authors: Krukov V A , Nguyen D T , Plyasov A V 
Published: September 2019

Abstract
The method of optimal geometric synthesis of four-bar cylindrical gear with related gears with one external and one internal gearing is proposed. The method is based on a new calculation system that increases the number of synthesis output parameters to six, which makes it possible to considerably expand the domain of existence of the synthesis problem solution with the simultaneous synthesis of two gearing. The software implementing the proposed technique is described. To solve the problem of nonlinear mathematical programming the library of Optimization Toolbox functions included in Matlab is used. Examples of calculations are given.
Geometric And Computer Modeling of Forming the Gear Wheels with Elliptical Centroid
Authors: Lyashkov A A , Reinhard A J , Murashev G E 
Published: September 2019

Abstract
A fairly simple and accurate methodology of automated forming of the teeth of a wheel with an elliptical centroid is proposed. This methodology is based on computer simulation of the real process of forming and does not require the application of complex mathematical body used in most traditional methods. The key point of the methodology is the proposed solution for determining the instantaneous centers of the cutting tool and the angles of its rotation around these centers. The relative position of the cutting tooth profiles is determined by two arrays of point coordinates: one on the elliptical centroid of the non-circular wheel, the other - on its equidistant curve. Compared to the traditional methods, this methodology is a universal and much more efficient and accurate one, especially for wheels with an elliptical centroid. The proposed automated solid-state computer simulation of the forming allows to obtain not only the envelope part of the profile, but also to observe possible formation of transition curves on it and undercutting, which leads to a qualitative solution of the profiling problem. According to the developed algorithms and programs, a computer model of a non-circular wheel is obtained, on the basis of which a corresponding item used in hydraulic unit pumps is made on a CNC machine.
Development of a measures complex to reduce the technogenic impact of launches of the promising Irtysh launch vehicle in the impact areas of the Baikonur cosmodrome
Authors: Suimenbayev B T , Trushlyakov V I , Yermoldina G T , Suimenbayeva Zh B , Bapyshev A M 
Published: September 2019

Abstract
Scientific and methodological approaches to minimizing the technogenic impact of launches of the promising launch vehicles of the Irtysh type with the oxygen-kerosene main liquid rocket engines of the Baiterek rocket complex in the impact areas of the Baikonur cosmodrome are considered. The basic directions for the reducing the technogenic impact of the worked-off booster of the first stage of the Irtysh type launch vehicle in the impact areas are: determining the optimal site for the worked-off stages (WS) fall in the selected zones of the impact areas that have the greatest resistance and the minimum cost on the restoration of the soil grounds of the site of the WS fall to its initial state - (A); controlled WS descent after separation from the LV into the designated site of the fall with an accuracy not exceeding the size of the selected optimal site - (B). To solve problems of the direction A, it is proposed to create an additional information and analytical system of the impact area. To solve problems of the direction B, possible design solutions are proposed based on the evaporation of unused liquid fuel residues in the WS tanks, and using the resulting vapor-gas mixtures for controlled WS descent to the dedicated zone of the impact area.
Research procedure of radial clearances in rolling bearings
Authors: Tarasov V N , Boyarkina I V , Tarasov E V , Boyarkin G N 
Published: September 2019

Abstract
In the result of the rolling bearing research it has been found that the bearing radial clearance, especially with a small number z of rolling elements z<15 besides technological factors depends on the rolling element location in the bearing during measurement. During operation the simple rolling bearing design is characterized by complex dynamic processes. In theoretical mechanics general technical calculations are carried out for absolutely rigid bodies that are not deformed during the working load application. This position is completely used in design diagrams as the deformations of races and rolling elements are not taken into consideration. If the bearing is manufactured and operated with a nominally reasonable value of the radial clearance, then the probability of its successful operation will be very high. During the bearing manufacturing it’s necessary to take into consideration the radial clearance as a geometric parameter along with other dimensions of the bearing. Analytical expressions for the radial clearance calculation have been obtained for the first time for odd and even layouts of the rolling element location in the bearing operating area. The calculation results for definite bearings are given. The justification of initial clearances and creation of the analytical method for the radial clearance determination represent a crucial task of the rolling bearing theory.
Rotating tethered system for active space debris removal
Authors: Trushlyakov V I , Yudintsev V V 
Published: September 2019

Abstract
A new technique for active debris removal using tethered space tug is presented. Instead of towing the captured debris object by pulling on the attached tether it is proposed to use the rotation of the tethered tug-debris system that allows to apply the tug’s thrust along the tether pushing the system. The rotation of the tug-debris tethered system around its center of mass provides necessary tension of the tether when the tug applies its thrust along the tether. To de-orbit the system the tug should apply its thrust periodically when the orientation of the tether relative to the the orbital velocity vector of the system ensures application of the impulse in the required direction. A simple mathematical model of tethered tug-debris system is developed which allows to estimate required angular rate of the system. A tether control law is proposed that reduces the amplitude of the tether oscillations during applying tug’s thrust.
Study of filler microstructure in magnetic soft composites
Authors: Valiev H H , Ya Minaev A , Stepanov G V , Karnet Yu N 
Published: September 2019

Abstract
Electron and atomic force microscopy were used for the study of magnetoactive filler surface microstructure in a magnetorheological composite. The particles redistribution phenomena of filler aggregates on the surface of elastomers under the action of a small external applied constant magnetic field are visualized. A model is proposed for the interaction of a magnetoactive filler with an elastomeric matrix of the composite, which explains the observed experimental results.