bluuebunny/crossref_metadata_2025_split huggingface dataset:
Ultrathin Co films with Pt and Au covers—magnetic and structural properties driven by Ga+ ion irradiation
Authors: Mazalski P , Ohnoutek L , Sveklo I , Beran L , Kurant Z , Powroźnik W , Wawro A , Liedke M O , Butterling M , Wagner A , Fassbender J , Hamrle J , Antoš R , Kletecka V , Veis M , Maziewski A 
Published: January 2021

Abstract
The X/Co 3 nm/Y (where X, Y = Au, Pt) trilayers with as deposited in-plane magnetization alignment were irradiated with 30 keV Ga+ ions in the wide range of ion fluence. The samples were investigated by means of complementary techniques: magneto-optical magnetometry and spectroscopy (in the photon energy range from 1.2 eV to 4.5 eV), magnetic force microscopy, positron annihilation spectroscopy, x-ray diffraction and reflectivity. Difference in miscibility of interface atoms is clearly manifested in various intermixing extent at Co/Pt and Co/Au interfaces and consequently in magnetic properties of the irradiated trilayers. Low irradiation fluence (∼1014 ions cm−2) leads to ∼1 nm interfaces broadening without visible surface etching for all samples, which is related with a distinct drop of magnetic anisotropy. However, the high irradiation fluence (∼5 × 1015 ions cm−2) results in enhanced interface broadening and significant surface etching (∼5 nm) partially removing also Co atoms. Tensile strains (up to 0.5%) were developed in the cover layers. The tensile strain, layers intermixing and the creation of Co–Pt(Au) alloys with different composition formed by irradiation are correlated with the increase of magnetic anisotropy. Moreover it was observed that substitution of Au instead of Pt (as a cap or buffer layer) results in substantial increase of perpendicular magnetic anisotropy. Maximal increase of magnetooptical parameters was observed for Pt/Co/Pt layer. Irradiation induced changes of concentration profiles are revealed using magnetooptical spectra, x-ray reflectivity spectra and simulations with use of binary collision approximation.
First evidence of dominant influence of E
×
B drifts on plasma cooling in an advanced slot divertor for tokamak power exhaust
Authors: Ma X. , Wang H.Q. , Guo H.Y. , Stangeby P.C. , Meier E.T. , Shafer M.W. , Thomas D.M. 
Published: January 2021

Abstract
Addressing power exhaust in tokamaks is presently recognized as one of the major remaining open issues for the development of fusion reactors. At the forefront of this endeavor is the effort to develop an advanced divertor by maximizing dissipation of plasma power and momentum inside the divertor. Here, we demonstrate, for the first time, that the electromagnetic (
E
×
B
) drifts exert a key influence on plasma and gas dynamics in a new advanced slot divertor in the DIII-D tokamak, named the small angle slot (SAS). SAS leverages the effect of drifts to achieve a highly dissipative divertor with electron temperature T
e ≲ 10 eV over a wide range of plasma densities, for ion
B
× ∇
B away from the divertor, as used for advanced tokamak operation on DIII-D. Modeling with the SOLPS-ITER code shows that for this drift direction, the
E
×
B
flow carries particles toward the outer common flux region (CFR) via the private flux region (PFR), reinforcing neutral recycling and enhancing divertor dissipation. In contrast, for the opposite field direction, the
E
×
B
flow carries particles away from the outer CFR into the PFR, offsetting the anticipated SAS geometric effects. This finding is an important step in the understanding of the behavior of advanced divertors for achieving a power exhaust solution for fusion reactors.
Influence of the degree of off-design of the traction nozzle of a jet reaction turbine on its efficiency
Authors: Vaneev S , Rodymchenko T , Meleychuk S , Baga V , Bolotnikova O 
Published: January 2021

Abstract
At the present stage of social development, the need for rational use of energy resources of the planet is particularly acute. Most countries have already faced the problem of the energy crisis. An appropriate way to solve this problem is the utilization of secondary energy resources. With the help of turbine generators, it is possible to reduce the pressure and utilize the potential energy of excess pressure of gas or vapours to produce electricity. Such units can be created based on a jet reaction turbine. The study aims to assess the impact of the degree of off-design of the traction nozzle on the efficiency of the jet reactive turbine. The analysis of the factors influencing the efficiency of the jet reaction turbine is carried out in the work. The obtained efficiency rate for the jet reactive turbine depending on the given dimensionless velocity of λout t at the inlet pressure of the inlet nozzle of 2, 4, 6 and 10 MPa in the design mode (at the degree of off-design of S = 1) and in the off-design modes of operation ( S> 1). Graphical dependencies of the jet reaction turbine efficiency rate on the given circular velocity of the impeller are constructed (U− = 0… 0.7). The research shows that with increasing pressure at the inlet to the inlet nozzle, the efficiency rate of the turbine increases, and the optimum of the efficiency rate is shifted towards the increase of the given circular velocity of the impeller, both in the design and off-design operating modes. It is found that the greatest value of the efficiency rate is acquired at the design mode of operation of the traction nozzle, i.e. at S = 1.
Influence of different volute casings theoretical methods design on pump working processes
Authors: Chernobrova A , Sotnyk M , Moloshnyi O , Antonenko S , Boiko V 
Published: January 2021

Abstract
The work is devoted to determining the influence of methods and recommendations for the design of a volute casing on the flow structure and the efficiency of the double-entry centrifugal pump. Volute casing designed by the constant-velocity method of the fluid according to the recommendations of A. Stepanoff, volute casing designed by the method of conservation of angular momentum of the flow, and the recommendations of C. Pfleiderer and A. Lomakin were designed and researched. The proposed designs were compared with the base volute casing. The analysis was performed based on the results of numerical simulation of the working process of the pump in the software ANSYS CFX at different flow rates. One impeller geometry and a constant volute casing outlet diameter were used to minimize the influence of other pump design factors on the working process of the volute casing. The distribution of pressure and velocity in the volute casing is analysed. Analysis of velocities and angular momentum along the volute casing showed the same deviation of them values. In general, the characteristics of the flow inside the volute casing conform indicated method. The article provides recommendations for choosing a method of designing a pump volute casing.
The analysis of the performance of a sewage pump in terms of the wear of hydraulic components
Authors: Moloshnyi O , Szulc P , Moliński G , Sapozhnikov S , Antonenko S 
Published: January 2021

Abstract
The paper presents the comparison of the performance of the three-blade centrifugal pump operating in sewage water in the function of time. Two conditions of the analysed pump were investigated: a new one and one after a long period of utilization. The main objects of research were the impeller, due to its enormous wear, and the L–shape wear ring. Three dimensional optical scanning was applied to reflect the real geometrical parameters of the analysed pump. The investigations were conducted by means of numerical simulations and a real test. The achieved results indicate the impact of the wear on the performance curves of middle specific speed sewage pump.
Improving the efficiency of the operating process of high specific speed torque-flow pumps by upgrading the flowing part design
Authors: Kondus V Y , Puzik R V , German V F , Panchenko V O , Yakhnenko S M 
Published: January 2021

Abstract
The article is devoted to the research of the torque-flow pump operating process. Its work is closely connected to the formation and stable functioning of the toroidal vortex. The theoretical bases of the formation of a toroidal vortex and the process of energy transfer in a torque-flow pump are considered in the research (vane and vortex components of the operating process). The fact of the presence of some additional hydraulic losses due to the mismatch of the location of the toroidal vortex center and the impeller blade edges has been established. The urgency of the paper is increasing the efficiency of torque-flow pump by improving its flowing part. The upgrade of the pump consists of the theoretical justification and practical implementation of the reduction of these additional hydraulic losses. In this aspect, the location of the impeller blade edge is aligned with the toroidal vortex center. The research was performed by conducting a numerical investigation. The calculations of a high specific speed torque-flow pump of three different design configurations of the impeller blades were performed. Practically confirmed increasing of the head (by 3.2 m) and efficiency (by 7-8%) of the pump with the second design of the impeller blades.
Characteristics improvement of labyrinth screw pump using design modification in screw
Authors: Andrenko P , Rogovyi A , Hrechka I , Khovanskyi S , Svynarenko M 
Published: January 2021

Abstract
The labyrinth screw pumps are widespread in the chemical and oil industries. The scope of the possible use of the labyrinth-screw pumps working in aggressive mediums is much wider in comparison with the pumps with similar pressure and flow parameters. This is due to the type of operation and lack of the mechanical friction of the parts. Increasing the pump flow rate can be achieved by reducing hydraulic friction resistance or profiling the inlet and outlet of the fluid flow. The flow channel of the labyrinth screw pump has been improved and a new design of its movable operating elements has been developed based on the proposed concept of jet resistor diodes. The reduction of hydraulic resistance in the flow channel of the pump with the working fluid flow in the forward direction and increasing the resistance of the diode made it possible to obtain a more efficient design. The results of improvement are compared with experimental data. The simulation of the flow in the pump is performed by solving the RANS equations with the SST turbulence model. The flow predictions in the flow section are obtained. The flow rate characteristics of typical and developed pumps are calculated. The developed pump design allows for increasing its flow rate by almost 10%. At the same time as the flow rate of the pump increases its power output. The efficiency of the industry-developed labyrinth screw pump application is proven by comparing the flow rate characteristics of the pumps.
Modifications of propeller pumps design algorithm. Numerical and laboratory tests
Authors: Altyntsev I , Homa D , Peczkis G 
Published: January 2021

Abstract
This article presents the new construction of a centrifugal impeller pump which supplies the cooling system in coal power plants. The article also shows the history of producing this kind if pumps for unified power units of 125 MW and 200 MW which dominate in Poland. The process of numerical analysis and conventional calculations leading to the improvement of qualities of the flowing system exceeding literature indicators are presented. The article shows the problems which appeared during assembling the pump in its target workplace. The results of the measurements of the pump flowing system in its target workplace are presented.
Developing a system and criteria for directed choice of technology to provide required quality of surfaces of flexible coupling parts for rotor machines
Authors: Melnyk V , Vlasovets V , Konoplianchenko Ie , Tarelnyk V , Dumanchuk M , Martsynkovskyy Vas , Semirnenko Yu , Semirnenko S 
Published: January 2021

AbstractThe paper discusses the process of normal friction and wear as a result of fretting corrosion, as well as measures to reduce its level. There are considered the issues of reliability and accuracy of the connection of “shaft - sleeve with key” type, which is of particular danger. The disadvantages of the considered connections are shown, namely the relative complexity of the disassembly-assembly processes; high level of stress concentration; the tendency to corrosion at contact. There has been proposed a physically based mathematical model of the wear process for the strengthened surfaces of the flexible coupling parts on the friction conditions. By using the friction work value, the model allows determining the wear expressed through the change in the surface roughness. A method has been developed for determining the constant of the wear equation for various materials of friction pairs. Using the energy and economic criteria, the technique of the integral description of the method for achieving the required quality of the surface layers of the elastic coupling parts is given. A mathematical model has been developed to reliably allow predicting the wear amount for the surfaces of the elastic coupling parts whose surface layers are formed in various ways. It is proposed a system for the directed choice of the technologies to produce the surface layers of the flexible coupling parts taking into account all the stages of their life cycles. In doing so, both economic and environmental requirements are also taken into consideration. The use of the system for the direct choice of the technology to ensure the required quality of the flexible coupling parts at the repair stage allows more economically solving the problem of restoring their performance. As practice shows, at this stage, the application of the results of the scientific research gives a significant economic effect.
Influence of operational changes of clearances in pump channels on the work of the automatic balancing device
Authors: Tarasevych Y , Sovenko N , Savchenko I 
Published: January 2021

Abstract
Automatic balancing devices are used to balance the axial force in many multistage centrifugal pump designs. Despite the obvious advantages of these devices their failure is one of the main reasons for the complete failure of the pump unit. The axial force acting on the pump rotor can be changed under pump operation in a sufficiently large range and up to several tens of tons. Usually the calculation of automatic balancing device is made under pump's operating parameters. At the same time it is possible the changing of value of the axial force generated by the automatic balancing device on the calculated parameters due to the interdependence of hydrodynamic processes in clearances of the flow part of the pump and in the clearances of the balancing device. The analysis of possible causes of the axial force value changes as a result of unbalanced pressure forces acting on pump impellers and counterbalancing of axial forces arising in face gap balancing device is presented. An improved methodology for calculating the estimation of the axial force arising in the balancing device using the example of industrial multistage centrifugal pump is proposed.
Prediction of stability against subsonic flutter for axial turbine machine compressor blade assemblies
Authors: Zinkovskii A P , Stel’makh A L 
Published: January 2021

Abstract
The developed method for prediction of their dynamic stability limit is described for the first flexural and torsional modes of vibrations against subsonic flutter. It involves the use of the database of the critical reduced frequencies of the blade vibrations as a dynamic stability limit within the wide range of variations of the following characteristics: phase angle of flexural, torsional and flexural-torsional vibrations of the adjacent blades; attack angle; reduced vibration frequency; geometric parameters for the airfoil and cascade; law of motion for blade airfoils. The algorithm realized as the numerical software assumes the determination of the critical reduced frequencies in the most loaded section of the full-scale blade assembly via the analysis of the distribution of the relative flow rate, attack angle, amplitudes of vibrations over the blade height and the subsequent comparison with the functional defining its critical value for different attack angles. The results of practical implementation of the developed procedure are given for the assessment of the stability of the blade assemblies of axial compressors in some modern aircraft gas-turbine engine at the first flexural mode of vibrations. It is implied that the proposed method allows one to select the optimal reduced frequency of vibrations of the blade assembly for the specified geometry of its peripheral sections and attack angle of the mainstream flow upon the condition of subsonic flutter at the engine design state.
Determination of material parameters of rubber and composites for computational modeling based on experiment data
Authors: Krmela J , Artyukhov A , Krmelová V , Pozovnyi O 
Published: January 2021

Abstract
The article deals with determination of material parameters of elastomer (rubber) for computational modeling based on experiment data - hardness and also determination of materials parameters of specific composite materials for next-generation tires. Mooney-Rivlin parameters of elastomers can be determined on the basis of the Shore A hardness. There are exist equations which can be used conversion of the mentioned hardness to material parameters of elastomers. The procedure is such that the Shore A hardness is converted to the elastic or shear modulus and then Mooney-Rivlin material parameters are determined from the modulus. But these equations can lead to different results for the same hardness. In this paper, these results are comparison. The results can be used as input material data of rubber seals of pump and compressor machinery for their computational modeling. Methods of determination of the modulus of elasticity of composite with elastomer matrix are necessary created based on experimental data of static tensile test of specimens of a radial tire casing. Next results can be applied for simulations of tires with interaction roads which used for modern passenger cars and trucks and the results can be applied for simulation of conveyor belts where elastomer is used.
Increasing fretting resistance of flexible element pack for rotary machine flexible coupling Part 1. Analysis of the reasons affecting fretting resistance of flexible elements for expansion couplings
Authors: Tarelnyk V , Hlushkova D , Martsynkovskyy V , Dumanchuk M , Antoszewski B , Kundera Cz , Konoplianchenko Ie , Tarelnyk N , Hudkov S , Zahorulko A 
Published: January 2021

Abstract
It has been made an analysis of the rotor machine flexible coupling (FC) failure reasons. As a result, it has been found out that the flexible coupling trouble-free operation period is limited by the pack of the flexible elements (FE) durability which depends on the fretting resistance of the individual flexible elements (plates) of the pack. The investigations with the use of an electron microscope have proved that there are at least three stages of the FE destruction: the formation of microfractures in the form of caverns at separate points of the FE destruction zone, which microfractures preserve microparticles of the destroyed metal in a confined space; weakening of the compression force affecting the plates and the wear product release from the fracture site; occurrence of abrasive wear resulting in the complete destruction of the FE. There has been substantiated the need in performing the FE stress-strain state analysis and determining the geometric and strain parameters of the strain zone, which can serve as a reserve for increasing the FE fretting resistance.
The scenario-based variations and causes of future surface soil moisture across China in the twenty-first century
Authors: Fan Keke , Zhang Qiang , Li Jianping , Chen Deliang , Xu Chong-Yu 
Published: January 2021

Abstract
Surface soil moisture (SSM) is a key factor for water and heat exchanges between land surface and the atmosphere. It is also important to water resources, agriculture, and ecosystems. In the backdrop of global warming, SSM variations and potential causes are not well-known at regional scales. Based on soil moisture (SM) data from GLDAS-Noah and 16 global climate models (GCMs) selected from 25 GCMs in CMIP5, we analyzed spatial distribution and temporal changes of SSM in China and quantified fractional contributions of four meteorological factors to the SSM variations. The selected models have the same direction of historic trends in SSM during 1981–2005 as those in the GLDAS SSM data which were also further used to calibrate the trends simulated by the 16 GCMs. Based on the calibration results for the 16 GCMs, future SSMs for nine regions were analyzed in mainland China under four Intergovernmental Panel on Climate Change emission scenarios. No significant changes were identified in SSM across most regions of mainland China under RCP2.6 scenario. However, there is a general wetting tendency in the arid regions and drying tendency across the humid regions under all the scenarios except RCP2.6. In general, the higher the global temperature raises, the more grids with significant increase or significant decrease in SSM. These findings contradicted prevailing view that wet regions get wetter and dry regions get drier. Attribution analysis indicates that precipitation acts as the major driver for SSM variations and contributes up to 43.4% of SSM variations across China. These results provide new insights into future SSM response to climate warming and a scientific basis to mitigation and adaptation works related to SSM in the future.
The use of computer visualization in the analysis of breathing curves
Authors: Berestneva O , Lyzin I , Yumasheva A , Marukhina O , Trufanov A 
Published: January 2021

Abstract
Researchers in diverse domains use advanced computer techniques to describe complex entities and processes and impressively visualize those which are often unavailable for direct observation. However, one should emphasize that computer visualization conception implies more than just a convenient, impressive, or high rate information transfer. It also considers a problem of perception, processing, and further cultivation of such important personal qualities as intuition, professional “talent”, and figurative thinking which are of value for experts in any domain. Computer visualization comprises traditionally such sophisticated techniques as computer graphics, animation and virtual reality. Traditionally, computer graphics has delivered strong instruments for creating, processing, and interacting with data representations. Interactive paradigm has led to emergence of a new scope within the problem of artificial intelligence, which is called cognitive computer graphics. The use of cognitive graphics allows physicians, analyzing modest volume of information, to draw significant conclusions. In whole, cognitive graphics forms a separate subfield in medical research. Visualization provides experts with data in current state of patients just to monitor their conditions continuously. In this article, we show the use of computer visualization to study characteristics (including network imprints) of such a common disease as bronchial asthma. The patients were grouped according to influence degree of psychological factors to the occurrence, progression and course stages of the disease. The study focuses on comparison and analysis of the patient’ spirograms and demonstrate presence of physiological and psycho-physiological features among patients with diagnoses of bronchial asthma. In this respect computer visualization provides a solid platform for thorough research and deep analysis in spirometry.