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Computational simulation of Turbulent Flow Around Tractor-Trailers

Fluid Dynamics & Materials Processing 2020年第1期16卷 91-103页

作者： D.O.Redchyts E.A.shkvar s.v.moiseienko Institute of Transport systems and Technologies of Ukrainian National Academy of science Dnipro49005Ukraine College of Engineering Zhejiang Normal UniversityJinhua321004China Kherson National Technical University Kherson73008Ukraine

A method to evaluate the properties of turbulent flow in proximity to the vehicle and close to the ground surface has been elaborated.Numerical simulations have been performed on the basis of the Unsteady Reynolds-averaged Navier-stokes equations(URANs)written with respect to an arbitrary curvilinear coordinate system.These equations have been solved using the spalart-Allmaras differential one-parametric turbulence model.The method of artificial compressibility has been used to improve the coupling of pressure and velocity in the framework of a finite volume approach.Time-averaged distributions of pressure fields,velocity components,streamlines in the entire area and near the tractor-trailer,as well as integral and distributed characteristic parameters(such as coefficients of pressure,friction and drag force)are presented.According to our results,the turbulent flow accelerates in the area of the tractor cabin and in the gap between surfaces.Above the driver’s cabin,a pressure drop occurs due to a sharp acceleration of flow in this area.Downstream,pressure is restored and becomes almost constant in proximity to the edge of the trailer.The dimensions of the separation area exceed the length of the transport system several times.Though agreement with experimental results is relatively limited due to the two-dimensional nature of the numerical simulations,the present approach succeeds in identifying the main physical effects involved in the considered dynamics.It might be used in future studies for initial approximate assessments of the influence of the vehicle shape on its aerodynamic characteristics.

关键词： High-speed vehicle tractor-trailer turbulent flow ground effect numerical modelling aerodynamic characteristics

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Control of Karman vortex street By Using Plasma Actuators

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Fluid Dynamics & Materials Processing 2019年第5期15卷 509-525页

作者： D.O.Redchyts E.A.shkvar s.v.moiseienko Institute of Transport systems and Technologies of National Academy of science of Ukraine Dnipro49005Ukraine College of Engineering Zhejiang Normal UniversityJinhua321004China Kherson National Technical University Kherson73008Ukraine

A mathematical model for unsteady electro-and aerodynamic processes in the presence of a plasma actuator has been elaborated through physical modeling of the dielectric barrier discharge.A specialized computational fluid dynamics package has been developed accordingly in order to calculate steady and unsteady laminar and turbulent flows.For the numerical simulation of the dielectric barrier discharge,in particular,two equations have been added to the Navier-stokes equations and solved.They describe the distribution of the applied voltage and the charged particles density.The impact of the plasma actuator on air has been accounted for through the Lorentz force,included as a source term in the momentum balance equation.The system of governing equations for the considered hydrodynamics and electrodynamics has been written in an arbitrary curvilinear coordinate system in dimensionless form and integrated in the framework of a finite volume method.A TvD scheme with a third-order IsNAs flow limiter has been chosen for the convective terms approximation.The obtained block-matrix system of linear algebraic equations has been solved by the generalized minimal residual(GMREs)method with ILU(k)preconditioning.Using this approach,the occurrence of a propulsion force,emerging as a result of the action of plasma actuators on a cylinder in quiescent air,has been investigated.The possibility to mitigate the cylinder drag coefficient with the help of the plasma actuators,due to the ensuing suppression of the Karman vortex street,has been demonstrated.

关键词： Plasma actuator dielectric barrier discharge turbulent flow Navier-stokes equations numerical simulation

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Conformally symmetric wormhole solutions supported by non-commutative geometry in f(Q,T)gravity

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Communications in Theoretical Physics 2024年第2期76卷 111-124页

作者： Chaitra Chooda Chalavadi v venkatesha N s Kavya s v Divya Rashmi Department of P.G.studies and Research in Mathematics Kuvempu UniversityShankaraghattaShivamogga 577451KarnatakaIndia Department of Mathematics Vidyavardhaka College of EngineeringMysuru—570002India

This paper investigates wormhole solutions within the framework of extended symmetric teleparallel gravity,incorporating non-commutative geometry,and conformal symmetries.To achieve this,we examine the linear wormhole model with anisotropic fluid under Gaussian and Lorentzian distributions.The primary objective is to derive wormhole solutions while considering the influence of the shape function on model parameters under Gaussian and Lorentzian distributions.The resulting shape function satisfies all the necessary conditions for a traversable wormhole.Furthermore,we analyze the characteristics of the energy conditions and provide a detailed graphical discussion of the matter contents via energy conditions.Additionally,we explore the effect of anisotropy under Gaussian and Lorentzian distributions.Finally,we present our conclusions based on the obtained results.

关键词： traversable wormhole f(Q T)gravity energy conditions non-commutative geometry conformal motion

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Thermogravimetric,kinetic study and gas emissions analysis of the thermal decomposition of waste-derived fuels

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Journal of Environmental sciences 2024年第3期137卷 155-171页

作者： vadim v.Dorokhov Galina s.Nyashina Pavel A.strizhak Heat and Mass Transfer Laboratory National Research Tomsk Polytechnic University30 Lenin AvenueTomsk 634050Russia

A wide range of wastes can potentially be used to generate thermal and electrical energy.The co-combustion of several types of waste as part of water-containing waste-derived fuels is a promising method for their recovery.In this research,we use thermogravimetric analysis and differential scanning calorimetry to study the thermal behavior and kinetics of coal slime,biomass,waste oils,and blends on their basis.We also analyze the concentrations of gaseous emissions.The results show that biomass,oils,and coal slime significantly affect each other in the course of their co-combustion when added to slurry fuels.The preparation of coal-water slurry based on slime and water reduced the ignition and burnout temperature by up to 16%.Adding biomass and waste oils additionally stimulated the slurry ignition and burnout,which occurred at lower temperatures.Relative to dry coal slime,threshold ignition temperatures and burnout temperatures decreased by 6%–9%and 17%–25%,respectively.Also,the use of biomass and waste oils as part of slurries inhibited NOхand sO_(2)emission by 2.75 times.According to the kinetic analysis,added biomass and waste turbine oil provide a 28%–51%reduction in the activation energy as compared to a coal-water slurry without additives.

关键词： Coal-water slurry Water-containing composite fuels Combustion Emission Kinetic TGA-DsC

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Physics of porous materials under extreme laser-generated conditions

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Matter and Radiation at Extremes 2024年第3期9卷 1-3页

作者： v.T.Tikhonchuk s.Weber Extreme Light Infrastructure ERIC ELI Beamlines Facility25241 DolníBrezanyCzech Republic CELIA University of Bordeaux33405 TalenceFrance

Porous materials offer unique possibilities for the production of plasmas with controlled density profiles for experiments on laser–matter interaction.They are of growing relevance to many applications,such as inertial confinement fusion,fundamental research,and secondary sources.Understanding the processes of transformation of a porous solid into a plasma is of fundamental interest and is needed for producing materials with desired properties.

关键词： interaction. properties. porous

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Interatomic Interaction Models for Magnetic Materials:Recent Advances

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Chinese Physics Letters 2024年第6期41卷 54-66页

作者： Tatiana s.Kostiuchenko Alexander v.shapeev Ivan s.Novikov Emanuel Institute of Biochemical Physics RAs 4 Kosygin StreetMoscow119334Russian Federation Independent investigator

Atomistic modeling is a widely employed theoretical method of computational materials science.It has found particular utility in the study of magnetic materials.Initially,magnetic empirical interatomic potentials or spinpolarized density functional theory(DFT)served as the primary models for describing interatomic interactions in atomistic simulations of magnetic systems.Furthermore,in recent years,a new class of interatomic potentials known as magnetic machine-learning interatomic potentials(magnetic MLIPs)has emerged.These MLIPs combine the computational efficiency,in terms of CPU time,of empirical potentials with the accuracy of DFT calculations.In this review,our focus lies on providing a comprehensive summary of the interatomic interaction models developed specifically for investigating magnetic materials.We also delve into the various problem classes to which these models can be applied.Finally,we offer insights into the future prospects of interatomic interaction model development for the exploration of magnetic materials.

关键词： materials interaction empirical

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Exploring van der Waals materials with high anisotropy:geometrical and optical approaches

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Light(science & Applications) 2024年第4期13卷 645-653页

作者： Aleksandr s.slavich Georgy A.Ermolaev Mikhail K.Tatmyshevskiy Adilet N.Toksumakov Olga G.Matveeva Dmitriy v.Grudinin Kirill v.voronin Arslan Mazitov Konstantin v.Kravtsov Alexander v.syuy Dmitry M.Tsymbarenko Mikhail s.Mironov sergey M.Novikov Ivan Kruglov Davit A.Ghazaryan Andrey A.vyshnevyy Aleksey v.Arsenin valentyn s.volkov Kostya s.Novoselov Moscow Center for Advanced studies Kulakova str.20Moscow 123592Russia. Emerging Technologies Research Center XPANCEOInternet CityEmmay TowerDubaiUnited Arab Emirates. Donostia International Physics Center(DIPC) Donostia/San-Sebastián 20018Spain. Institute of Materials Ecole Polytechnique Federale de Lausanne1015 LausanneSwitzerland. Department of Chemistry Lomonosov Moscow State UniversityMoscow 119991Russia. Laboratory of Advanced Functional Materials Yerevan State UniversityYerevan 0025Armenia. National Graphene Institute(NGI) University of ManchesterManchester M139PLUK. Department of Materials science and Engineering National University of SingaporeSingapore 03-09 EASingapore. Institute for Functional Intelligent Materials National University of Singapore117544 SingaporeSingapore

The emergence of van der Waals(vdW)materials resulted in the discovery of their high optical,mechanical,and electronic anisotropic properties,immediately enabling countless novel phenomena and applications.such success inspired an intensive search for the highest possible anisotropic properties among vdW materials.Furthermore,the identification of the most promising among the huge family of vdW materials is a challenging quest requiring innovative approaches.Here,we suggest an easy-to-use method for such a survey based on the crystallographic geometrical perspective of vdW materials followed by their optical characterization.Using our approach,we found As2s3 as a highly anisotropic vdW material.It demonstrates high in-plane optical anisotropy that is~20%larger than for rutile and over two times as large as calcite,high refractive index,and transparency in the visible range,overcoming the century-long record set by rutile.Given these benefits,As2s3 opens a pathway towards nextgeneration nanophotonics as demonstrated by an ultrathin true zero-order quarter-wave plate that combines classical and the Fabry–Pérot optical phase accumulations.Hence,our approach provides an effective and easy-to-use method to find vdW materials with the utmost anisotropic properties.

关键词： anisotropy anisotropic high

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Tensor force impact on shell evolution in neutron-rich si and Ni isotopes

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Chinese Physics C 2024年第4期48卷 95-106页

作者： s.v.sidorov A.s.Kornilova T.Yu.Tretyakova Faculty of Physics Lomonosov Moscow State UniversityMoscow 119991Russia skobeltsyn Institute of Nuclear Physics Lomonosov Moscow State UniversityMoscow 119991Russia

The influence of the tensor interaction of nucleons on the characteristics of neutron-rich silicon and nickel isotopes was studied in this work.Tensor forces are considered within the framework of the Hartree-Fock approach with the skyrme interaction.The addition of a tensor component of interaction is shown to improve the description of the splittings between different single-particle states and decrease nucleon-nucleon pairing correlations in silicon and nickel nuclei.special attention was directed toward the role of isovector tensor forces relevant to the interaction of like nucleons.

关键词： nuclear shell model tensor interaction silicon isotopes nickel isotopes

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Emission colour tuning in KLnF_(4):Yb^(3+),Er^(3+)/Ho^(3+)phosphor

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Journal of Rare Earths 2024年第1期42卷 57-65,I0002页

作者： Janani K Gayathri E vijayatha v Ramasubramanian s Thiyagarajan P Department of science and Humanities Nehru Institute of TechnologyKaliapuramThirumalayampalayamCoimbatoreIndia Department of sciences Amrita School of Physical SciencesAmrita Vishwa VidyapeethamCoimbatoreIndia Department of Physics Anna UniversityChennaiIndia

KLnF_(4):Yb^(3+),Er^(3+)/Ho^(3+)(Ln=Y,Yb,Gd)phosphors were prepared by solid-state reaction technique.For each of the Yb^(3+)/Er^(3+)and Yb^(3+)/Ho^(3+)co-doped phosphors independently,phase confirmation and morphological examination were accomplished using the X-ray diffraction technique and scanning electron microscope analysis.X-ray photoelectron spectroscopy analysis shows the charge state and existence of lanthanides and dopants.Upconversion luminescence emissions of green and red colour were detected for the synthesized phosphors.The changes in the upconverted emission intensities and colour output pertaining to the change of the lanthanide host matrix along with dopants were investigated for the prepared phosphors.In the upconversion luminescence,erbium-doped samples exhibit a predominance of red emission while holmium-doped samples display a prevalence of green emission.The rare-earth Er/Ho doped KYbF4shows strong red emission compared to other hosts.KYF_(4):Yb,Er/Ho exhibits relatively significant green upconve rsion emissions,while Yb,Er-doped KGdF_(4)host displays a 10-fold increase in green/red emission ratio with an increase in the input power of 20-780 mW.Downshifting photoluminescence studies and decay curve analysis were carried out using Uv light excitation for the developed phosphors.A higher lifetime of 2.2 ms was measured for the downshifting red emission in the Ho doped KYbF_(4)sample.This study suggests a potential for colour tunability in the upconversion and downshifting emissions through host modifications to the fluoride phosphor.

关键词： Rare earths Energy transfer upconversion Downshifting Colour coordinates

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Antibacterial HA-coatings on bioresorbable Mg alloy

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Journal of Magnesium and Alloys 2024年第5期12卷 1965-1985页

作者： K.v.Nadaraia D.v.Mashtalyar M.A.Piatkova A.I.Pleshkova I.M.Imshinetskiy M.s.Gerasimenko E.A.Belov v.v.Kumeiko D.N.Kozyrev K.A.Fomenko v.v.Mostovaya B.R.Torpanov A.R.Biktimirov I.s.Osmushko s.L.sinebryukhov s.v.Gnedenkov Institute of Chemistry FEB RAs Far Eastern Federal University A.v.Zhirmunsky National scientific Center of Marine Biology FEB RAs Regional Clinical Dermatovenerological Dispensary NMIC “Treatment and Rehabilitation Center”

In this study, a calcium-phosphate coating was formed on a Mg-Mn-Ce alloy by the plasma electrolytic oxidation(PEO). The antibiotic vancomycin, widely used in the treatment of infections caused by staphylococcus aureus(s. aureus), was impregnated into the coating.samples with vancomycin showed high bactericidal activity against s. aureus. The mechanical and electrochemical properties of the formed coatings were studied, as well as in vitro cytotoxicity tests and in vivo tests on mature male rats were performed. According to sEM,EDs, XRD and XPs data, coatings had a developed morphology and contained hydroxyapatite, which indicates high biocompatibility.The analysis of roughness of coatings without and with vancomycin did not reveal any differences, confirming the high roughness of the samples. During electrochemical tests, an increase in corrosion resistance by more than two times after the application of PEO coatings was revealed. According to the results of an in vivo study, after 28 days of the implantation of samples with calcium phosphate PEO coating and vancomycin, no signs of inflammation were observed, while an inflammatory reaction developed in the area of implantation of bare alloy,followed by encapsulation. Antibiotic release tests from the coatings show a sharp decrease in the concentration of the released antibiotic on day 7 and then a gradual decrease until day 28. Throughout the experiment, no significant deviations in the condition and behavior of the animals were observed; clinical tests did not reveal a systemic toxic reaction.

关键词： Bioactive coatings Biocompatibility Mg alloy Plasma electrolytic oxidation Hydroxyapatite vancomycin

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