This study focuses on coupled vibrations of rotating thin-walled composite beams subjected to hygrothermal effects.In the existing literature,many studies have been conducted on coupled bending-torsional vibration and...This study focuses on coupled vibrations of rotating thin-walled composite beams subjected to hygrothermal effects.In the existing literature,many studies have been conducted on coupled bending-torsional vibration and resonance in hygrothermal environments.Few studies considered the coupled flapwise-edgewise and resonances of composite thin-walled beams.Considering this,the flapwise-edgewise coupling effects and resonant characteristics of rotating thin-walled composite beams in a hygrothermal environment are studied.The Rayleigh–Ritz method is used to solve the equations of the beam.Results indicate that flapwise-edgewise coupling factors are essential for the vibration analysis of rectangular thin-walled beams.The ply angle and setting angle strongly affect the internal and external resonances.Large ply angles can significantly reduce the chances of primary internal and external resonances occurring when the permitted rotational speed is lower.展开更多
In semiconductor precision packaging and other applications involving alignment of automated equipment,the nonlinear motion caused by structural characteristics and friction effects on torque-type rotating motion stag...In semiconductor precision packaging and other applications involving alignment of automated equipment,the nonlinear motion caused by structural characteristics and friction effects on torque-type rotating motion stages seriously affects output accuracy and stability.To solve this problem,the motion characteristics of a rotating stage and the mechanism by which friction nonlinearity influences accuracy are analyzed in detail.In addition,a compound control strategy based on a kinematic model and the Stribeck friction model is designed.A friction disturbance observer based on output position feedback is improved for simple parameter tuning.Finally,an experimental system is constructed to carry out validation tests,including identification of nonlinear characteristics and performance comparisons.The experimental results show that the linear tracking error of the torque-type rotating stage is less than 1.47µm after adoption of the proposed model-based composite control strategy,and the corresponding rotary angle deviation is less than 0.0153°.The linearity of output motion is increased to 97.59%and the error compensation effect is improved by 51.6%compared with the PID control method.The experimental results confirm that the analysis method adopted here and the proposed compensation strategy can effectively reduce frictional nonlinearity and improve motion accuracy.The proposed method can also be applied to other precision electromechanical systems.展开更多
A rotating disc column (RDC) with inner diameter 68 mm and 28 compartments is used in this study. Parameters including Sauter mean diameter, hold-up and mass transfer coefficient are measured experimentally un-der dif...A rotating disc column (RDC) with inner diameter 68 mm and 28 compartments is used in this study. Parameters including Sauter mean diameter, hold-up and mass transfer coefficient are measured experimentally un-der different operating conditions. The correlations in literature for molecular diffusion and enhancement factor equation including eddy diffusion, circulation and oscillation of drops are evaluated. A new equation for the effec-tive diffusion coefficient as a function of Reynolds number is proposed. The calculated values of mass transfer co-efficient and column height from the previous equations and present equation are compared with the experimental data. The results from the present equation are in very good agreement with the experimental results, which may be used in designing RDC columns.展开更多
Coriolis effect is considered in the analysis of a rotating piezoelectric hollow cylinder. An inhomogeneous Bessel equation governing the radial mechanical displacement is derived, which can be approximated as an Eule...Coriolis effect is considered in the analysis of a rotating piezoelectric hollow cylinder. An inhomogeneous Bessel equation governing the radial mechanical displacement is derived, which can be approximated as an Euler type differential equation when the cylinder is very thin. Numerical examples show that the Coriolis effect can he significant under certain conditions.展开更多
Dynamic coupling modeling and analysis of rotating beams based on the nonlinear Green-Lagrangian strain are introduced in this work.With the reservation of the axial nonlinear strain,there are more coupling terms for ...Dynamic coupling modeling and analysis of rotating beams based on the nonlinear Green-Lagrangian strain are introduced in this work.With the reservation of the axial nonlinear strain,there are more coupling terms for axial and transverse deformations.The discretized dynamic governing equations are obtained by using the finite element method and Lagrange’s equations of the second kind.Time responses are conducted to compare the proposed model with other previous models.The stretching deformation due to rotating motion is observed and calculated by special formulations under dynamic equilibrium.The stretching deformation and the change of the associated equilibrium position are taken into account to analyze the free vibration and frequency response of the rotating beams.Analytical and numerical comparisons show that the proposed model can provide reliable results,while the previous models may lead to imprecise results,especially in high-speed conditions.展开更多
The three-dimensional(3D)spheroid culture has been widely used as an important tool in biological research.Although several techniques have been established to prepare cell spheroids,fast and controllable production r...The three-dimensional(3D)spheroid culture has been widely used as an important tool in biological research.Although several techniques have been established to prepare cell spheroids,fast and controllable production remains one of the major challenges.In this study,a simple but efficient method utilizing the inertial focusing effect in rotating hanging droplets is demonstrated for the rapid and controllable production of cell spheroids.展开更多
We report microstructure,magnetocaloric effect and thermal transfer properties of highly orientated Nd0.8Pr0.2Co5 alloy prepared by powder metallurgical processing.Two spin-reorientation transitions of easy magnetizat...We report microstructure,magnetocaloric effect and thermal transfer properties of highly orientated Nd0.8Pr0.2Co5 alloy prepared by powder metallurgical processing.Two spin-reorientation transitions of easy magnetization direction,easy plane to easy cone at TSR1=206 K,easy cone to easy axis at TSR2=242 K,are observed.The present textured alloy exhibits a rotating entropy change of 2.6 J/(kg·K)and refrigerant capacity of 155 J/kg under a magnetic field of 2 T,and high thermal conductivity of 11 W/(m·K).The sintered Nd0.8Pr0.2Co5 alloy with good combination of excellent magnetocaloric and thermal transfer properties are promising for scientific research and practical applications as room-temperature rotating magnetic refrigeration materials.展开更多
This article investigates an unbiased analysis for the unsteady two-dimensional laminar flow of an incompressible, electrically and thermally conducting fluid across the space separated by two infinite rotating permea...This article investigates an unbiased analysis for the unsteady two-dimensional laminar flow of an incompressible, electrically and thermally conducting fluid across the space separated by two infinite rotating permeable walls.The influence of entropy generation, Hall and slip effects are considered within the flow analysis. The problem is modeled based on valid physical arguments and the unsteady system of dimensionless PDEs (partial differential equations) are solved with the help of Finite Difference Scheme. In the presence of pertinent parameters, the precise movement of the flow in terms of velocity, temperature, entropy generation rate, and Bejan numbers are presented graphically, which are parabolic in nature. Streamline profiles are also presented, which exemplify the accurate movement of the flow. The current study is one of the infrequent contributions to the existing literature as previous studies have not attempted to solve the system of high order non-linear PDEs for the unsteady flow with entropy generation and Hall effects in a permeable rotating channel. It is expected that the current analysis would provide a platform for solving the system of nonlinear PDEs of the other unexplored models that are associated to the two-dimensional unsteady flow in a rotating channel.展开更多
In this article,we investigate the nonrelativistic quantum motion of a charged particle within a rotating frame,taking into account the Aharonov–Bohm(AB)effect and a uniform magnetic field.Our analysis entails the de...In this article,we investigate the nonrelativistic quantum motion of a charged particle within a rotating frame,taking into account the Aharonov–Bohm(AB)effect and a uniform magnetic field.Our analysis entails the derivation of the equation of motion and the corresponding radial equation to describe the system.Solving the resulting radial equation enables us to determine the eigenvalues and eigenfunctions,providing a clear expression for the energy levels.Furthermore,our numerical analysis highlights the substantial influence of rotation on both energy levels and optical properties.Specifically,we evaluate the photoionization cross-section with and without the effects of rotation.To elucidate the impact of rotation on the photoionization process of the system,we present graphics that offer an appealing visualization of the intrinsic nature of the physics involved.展开更多
In this work,we have investigated the rotating effect on the thermodynamic properties of a 2D quantum ring.Accordingly,we have considered the radial potential of a 2D quantum ring and solved the Schrödinger equat...In this work,we have investigated the rotating effect on the thermodynamic properties of a 2D quantum ring.Accordingly,we have considered the radial potential of a 2D quantum ring and solved the Schrödinger equation in the presence of the Aharonov-Bohm effect and a uniform magnetic field for the considered potential.According to the solution of the equation,we calculated the eigenvalues and eigenfunctions of the considered system.Using the calculated energy spectrum,we obtained the partition function and thermodynamic properties of the system,such as the mean energy,specific heat,entropy and free energy.Our results show that the rotating effect has a significant influence on the thermophysical properties of a 2D quantum ring.We also study other effects of the rotating term:(1)the effect of different values of rotating parameters,and(2)the effect of negative rotation on the thermodynamic properties of the system.Our results are discussed in detail.展开更多
The general relativistic frame dragging effect on the properties,such as the moments of inertia and the radiiof gyration of fast rotating neutron stars with a uniform strong magnetic field,is calculated accurate to th...The general relativistic frame dragging effect on the properties,such as the moments of inertia and the radiiof gyration of fast rotating neutron stars with a uniform strong magnetic field,is calculated accurate to the first orderin the uniform angular velocity.The results show that compared with the corresponding non-rotating static sphericalsymmetric neutron star with a weaker magnetic field,a fast rotating neutron star(millisecond pulsar)with a strongermagnetic field has a relative smaller moment of inertia and radius of gyration.展开更多
We discussed the unsteady flow of an incompressible viscous fluid in a rotating parallel plate channel bounded on one side by a porous bed under the influence of a uniform transverse magnetic field taking hall current...We discussed the unsteady flow of an incompressible viscous fluid in a rotating parallel plate channel bounded on one side by a porous bed under the influence of a uniform transverse magnetic field taking hall current into account. The perturbations are created by a constant pressure gradient along the plates in addition to the non-torsional oscillations of the upper plate. The flow in the clean fluid region is governed by Navier-Stoke’s equations while in the porous bed the equations are based on Darcy-Lapwood model. The exact solutions of velocity in the clean fluid and the porous medium consist of steady state and transient state. The time required for the transient state to decay is evaluated in detail and ultimate quasi-steady state solution has been derived analytically and also its behaviour is computationally discussed with reference to different flow parameters. The shear stresses on the boundaries and the mass flux are also obtained analytically and their behaviour is computationally discussed.展开更多
The thermodynamic features of the Reiner-Rivlin nanoliquid flow induced by a spinning disk are analyzed numerically.The non-homogeneous two-phase nanofluid model is considered to analyze the effect of nanoparticles on...The thermodynamic features of the Reiner-Rivlin nanoliquid flow induced by a spinning disk are analyzed numerically.The non-homogeneous two-phase nanofluid model is considered to analyze the effect of nanoparticles on the thermodynamics of the Reiner-Rivlin nanomaterial,which also includes a temperature-dependent heat source(THS)and an exponential space-dependent heat source(ESHS).Further,the transfer of heat and mass is analyzed with velocity slip,volume fraction jump,and temperature jump boundary conditions.The finite difference method-based routine is used to solve the complicated differential equations formed after using the von-Karman similarity technique.Limiting cases of the present problem are found to be in good agreement with benchmarking studies.The relationship of the pertinent parameters with the heat and mass transport is scrutinized using correlation,which is further evaluated based on the probable error estimates.Multivariable models are fitted for the friction factor at the disk and heat transport,which accurately predict the dependent variables.The Reiner-Rivlin nanoliquid temperature is influenced comparatively more by the ESHS than by THS.The Nusselt number is decreased by the ESHS and THS,whereas the friction factor at the disk is predominantly decremented by the wall roughness aspect.The increment in the non-Newtonian characteristic of the liquid leads more fluid to drain away in the radial direction far from the disk compared with the fluid nearby the disk in the presence of the centrifugal force during rotation.The increased thermal and volume fraction slip lowers the nanoliquid temperature and nanoparticle volume fraction profiles.展开更多
Based on the equations of state from the relativistic mean field theory without and with the inclusion of strangeness-bearing hyperons, we study the dimensionless spin parameter j = cJ/（GM2） of uniformly rotat- ing ...Based on the equations of state from the relativistic mean field theory without and with the inclusion of strangeness-bearing hyperons, we study the dimensionless spin parameter j = cJ/（GM2） of uniformly rotat- ing neutron stars. It is shown that the maximum value of the spin parameter jmax of a neutron star rotating at the Keplerian frequency fK is .jmax - 0.7 when the star mass M 〉 0.SM⊙, which is sustained for various versions of equations of state without and with hyperons. The relationship between j and the scaled rotation frequency f /fK is found to be insensitive to the star mass or the adopted equation of state in the models without hyperons. However, the emergence of byperons in neutron stars will lead to an uncertainty of the spin parameter j, which in turn could generate a complexity in the theoretical study of the quasi-periodic oscillations observed in disk-accreting compact-star systems.展开更多
In this paper, we make an initial value investigation of the unsteady flow of incompressible viscous fluid between two rigid non-conducting rotating parallel plates bounded by a porous medium under the influence of a ...In this paper, we make an initial value investigation of the unsteady flow of incompressible viscous fluid between two rigid non-conducting rotating parallel plates bounded by a porous medium under the influence of a uniform magnetic field of strength H0 inclined at an angle of inclination α with normal to the boundaries taking hall current into account. The perturbations are created by a constant pressure gradient along the plates in addition to the non-torsional oscillations of the upper plate while the lower plate is at rest. The flow in the porous medium is governed by the Brinkman’s equations. The exact solution of the velocity in the porous medium consists of steady state and transient state. The time required for the transient state to decay is evaluated in detail and the ultimate quasi-steady state solution has been derived analytically. Its behaviour is computationally discussed with reference to the various governing parameters. The shear stresses on the boundaries are also obtained analytically and their behaviour is computationally discussed.展开更多
Objective To compare the preliminary clinical outcome between fixed platform and rotating high-flexion prosthesis following total knee replacement(TKR).Methods Form January 2007 to December 2009,68 patients with osteo...Objective To compare the preliminary clinical outcome between fixed platform and rotating high-flexion prosthesis following total knee replacement(TKR).Methods Form January 2007 to December 2009,68 patients with osteoarthritis of展开更多
Volume effect has been extensively investigated in several families of solid electrolytes, i.e., expanding the skeleton lattice by bigger-size substitution favors the ionic conduction. However, this effect is not appl...Volume effect has been extensively investigated in several families of solid electrolytes, i.e., expanding the skeleton lattice by bigger-size substitution favors the ionic conduction. However, this effect is not applicable in α-Li2SO4 and α-Na3PO4 based inorganic ionic plastic crystal electrolytes, a unique family of solid electrolytes. Here, it is proposed that the underlying rotational motion effect of polyanion, which is actually inhibited by the substitution of bigger-size polyanion in single-phase solid solution region and causes the unexpected lowering of the ionic conductivity instead, should need the more consideration. Furthermore, through utilizing the rotational motion effect of polyanion, it is given that a new explanation of the ionic conductivities of Li10MP2S12 （M = Si, Ge, Se） electrolytes deviating from the volume effect. These results inspire new vision of rationalization of the high-performance solid electrolytes by tuning the rotational motion effect of polyanion.展开更多
Based on the surface elasticity theory of GurtinMurdoch, thermo-elastic fields within rotating nanoshafts with varying material properties subjected to a thermal field are explicitly examined. Accounting for the surfa...Based on the surface elasticity theory of GurtinMurdoch, thermo-elastic fields within rotating nanoshafts with varying material properties subjected to a thermal field are explicitly examined. Accounting for the surface energy effect, the nonclassical boundary conditions are enforced in the cases of fixed-free and free-free conditions. The effects of variation of material properties, temperature of the environment, angular velocity, and radius of the outer radius on the radial displacement, hoop and radial stresses are investigated. In all performed studies, the role of the surface effect on the thermo-elastic field of the nanostructure is methodically discussed.展开更多
The rapid development of high-speed railway networks requires advanced methods for analysing vibration and sound radiation characteristics of a fast rotating train wheel subject to a vertical harmonic wheel-rail force...The rapid development of high-speed railway networks requires advanced methods for analysing vibration and sound radiation characteristics of a fast rotating train wheel subject to a vertical harmonic wheel-rail force. In order to consider the rotation of the wheel and at the same time increase the computational efficiency, a procedure is adapted in this paper taking advantage of the axial symmetry of the wheel. In this procedure, a recently developed 2.5D finite element method, which can consider wheel rotation but only requires a 2D mesh over a cross section containing the wheel axis, is used to calculate the vibration response of the wheel. Then, the vibration response of the wheel is taken as acoustic boundary condition and the 2.5D acoustic boundary element method, which only requires a 1D mesh over the boundary of the above cross section, is utilised to calculate the sound radiation of the wheel. These 2.5D methods and relevant programs are validated by comparing results from this procedure with those from conventional 3D analyses using commercial software. The comparison also demonstrates that these 2.5D methods have a much higher computational efficiency. Using the 2.5D methods, we study the wheel rotation speed influences on the factors including the vertical receptance of the wheel at wheel-rail contact point, sound pressure level at a pre-defined standard measurement point, radiated sound power level, directivity of the radia- tion, and contribution of each part of the wheel. It can be concluded that the wheel rotation speed splits most peaks of the vertical receptance at the wheel-rail contact point, sound pressure levels at the field, and the sound power level of the wheel into two peaks. The directivity and power contribution of the wheel are also significantly changed by the wheel rotation speed. Therefore, the rotation of a train wheel should be taken into account when calculating its vibration and sound radiation.展开更多
This communiquéis opted to study the flow of nanofluid because of heated disk rotation subjected to the convective boundaries with chemical reaction of first order.Wherein Buongiorno’s model for nanofluids is us...This communiquéis opted to study the flow of nanofluid because of heated disk rotation subjected to the convective boundaries with chemical reaction of first order.Wherein Buongiorno’s model for nanofluids is used due to its wide range of applications and the rotating disk under investigation is permeable.Small magneto Reynolds parameter and boundary layer assumptions are carried out to formulate the problem.The system of nonlinear partial differential equations governing the flow problem is converted into the set of ordinary differential equations by using particular relations known as Von Karman transformations.The complicated set of coupled ordinary differential equations with complicated boundary conditions is set to solve by an analytical technique Homotopy Analysis Method(HAM).Whereby the results obtained by the aforementioned method are provided analytically and analyzed graphically.Also validation of the work is confirmed by providing comparison of previous works in tabular form.Effect of chemical reaction parameter on mass transfer rate is also highlighted tabularly for its increament.Nusselt and Sherwood numbers calculated and compared to the like literature and found in good agreement.展开更多
基金supported by the National Natural Science Foundation of China(Grant Nos.11902002 and 51705002)the Sichuan Provincial Natural Science Foundation(Grant No.2022NSFSC0275)the University Outstanding Youth Researcher Support Program of the Education Department of Anhui Province,and the Teaching Project of the Education Department of Anhui Province(Grant No.2022xxsfkc023).
文摘This study focuses on coupled vibrations of rotating thin-walled composite beams subjected to hygrothermal effects.In the existing literature,many studies have been conducted on coupled bending-torsional vibration and resonance in hygrothermal environments.Few studies considered the coupled flapwise-edgewise and resonances of composite thin-walled beams.Considering this,the flapwise-edgewise coupling effects and resonant characteristics of rotating thin-walled composite beams in a hygrothermal environment are studied.The Rayleigh–Ritz method is used to solve the equations of the beam.Results indicate that flapwise-edgewise coupling factors are essential for the vibration analysis of rectangular thin-walled beams.The ply angle and setting angle strongly affect the internal and external resonances.Large ply angles can significantly reduce the chances of primary internal and external resonances occurring when the permitted rotational speed is lower.
基金funded by the European Union’s Horizon 2020 Research and Innovation Program under the Marie Sklodowska-Curie Grant Agreement(Grant No.101026104)by the National Natural Science Foundation of China(Grant No.U20A6004)in part by the State Key Laboratory of Precision Electronics Manufacturing Technology and Equipment(Grant No.JMDZ202314).
文摘In semiconductor precision packaging and other applications involving alignment of automated equipment,the nonlinear motion caused by structural characteristics and friction effects on torque-type rotating motion stages seriously affects output accuracy and stability.To solve this problem,the motion characteristics of a rotating stage and the mechanism by which friction nonlinearity influences accuracy are analyzed in detail.In addition,a compound control strategy based on a kinematic model and the Stribeck friction model is designed.A friction disturbance observer based on output position feedback is improved for simple parameter tuning.Finally,an experimental system is constructed to carry out validation tests,including identification of nonlinear characteristics and performance comparisons.The experimental results show that the linear tracking error of the torque-type rotating stage is less than 1.47µm after adoption of the proposed model-based composite control strategy,and the corresponding rotary angle deviation is less than 0.0153°.The linearity of output motion is increased to 97.59%and the error compensation effect is improved by 51.6%compared with the PID control method.The experimental results confirm that the analysis method adopted here and the proposed compensation strategy can effectively reduce frictional nonlinearity and improve motion accuracy.The proposed method can also be applied to other precision electromechanical systems.
文摘A rotating disc column (RDC) with inner diameter 68 mm and 28 compartments is used in this study. Parameters including Sauter mean diameter, hold-up and mass transfer coefficient are measured experimentally un-der different operating conditions. The correlations in literature for molecular diffusion and enhancement factor equation including eddy diffusion, circulation and oscillation of drops are evaluated. A new equation for the effec-tive diffusion coefficient as a function of Reynolds number is proposed. The calculated values of mass transfer co-efficient and column height from the previous equations and present equation are compared with the experimental data. The results from the present equation are in very good agreement with the experimental results, which may be used in designing RDC columns.
基金supported by the National Natural Science Foundation of China (11321202)the Fundamental Research Funds for the Central Universities (2016XZZX001-05)
文摘Coriolis effect is considered in the analysis of a rotating piezoelectric hollow cylinder. An inhomogeneous Bessel equation governing the radial mechanical displacement is derived, which can be approximated as an Euler type differential equation when the cylinder is very thin. Numerical examples show that the Coriolis effect can he significant under certain conditions.
基金the National Natural Science Foundation of China(Nos.12232012,12202110,12102191,and 12072159)the Fundamental Research Funds for the Central Universities of China(No.30922010314)the Natural Science Foundation of Guangxi Province of China(No.2020GXNSFBA297010)。
文摘Dynamic coupling modeling and analysis of rotating beams based on the nonlinear Green-Lagrangian strain are introduced in this work.With the reservation of the axial nonlinear strain,there are more coupling terms for axial and transverse deformations.The discretized dynamic governing equations are obtained by using the finite element method and Lagrange’s equations of the second kind.Time responses are conducted to compare the proposed model with other previous models.The stretching deformation due to rotating motion is observed and calculated by special formulations under dynamic equilibrium.The stretching deformation and the change of the associated equilibrium position are taken into account to analyze the free vibration and frequency response of the rotating beams.Analytical and numerical comparisons show that the proposed model can provide reliable results,while the previous models may lead to imprecise results,especially in high-speed conditions.
基金the Fundamental Research Funds for the Central Universities(Nos.JKF-YG20-B008 and YWF-19-BJ-J-132)the National Natural Science Foundation of China(Nos.11674019 and 12072010)for the financial supportpartially supported by Yunnan Baiyao Group Co.Ltd.
文摘The three-dimensional(3D)spheroid culture has been widely used as an important tool in biological research.Although several techniques have been established to prepare cell spheroids,fast and controllable production remains one of the major challenges.In this study,a simple but efficient method utilizing the inertial focusing effect in rotating hanging droplets is demonstrated for the rapid and controllable production of cell spheroids.
基金the National Natural Science Foundation of China(51601208,51531008,51601209)the Fujian Institute of Innovation,Chinese Academy of Sciences(FJCXY18040301)。
文摘We report microstructure,magnetocaloric effect and thermal transfer properties of highly orientated Nd0.8Pr0.2Co5 alloy prepared by powder metallurgical processing.Two spin-reorientation transitions of easy magnetization direction,easy plane to easy cone at TSR1=206 K,easy cone to easy axis at TSR2=242 K,are observed.The present textured alloy exhibits a rotating entropy change of 2.6 J/(kg·K)and refrigerant capacity of 155 J/kg under a magnetic field of 2 T,and high thermal conductivity of 11 W/(m·K).The sintered Nd0.8Pr0.2Co5 alloy with good combination of excellent magnetocaloric and thermal transfer properties are promising for scientific research and practical applications as room-temperature rotating magnetic refrigeration materials.
基金Support of the National Natural Science Foundation of China under Grant Nos.51709191 and 51706149Key Laboratory of Advanced Reactor Engineering and Safety,Ministry of Education under Grant No.ARES-2018-10
文摘This article investigates an unbiased analysis for the unsteady two-dimensional laminar flow of an incompressible, electrically and thermally conducting fluid across the space separated by two infinite rotating permeable walls.The influence of entropy generation, Hall and slip effects are considered within the flow analysis. The problem is modeled based on valid physical arguments and the unsteady system of dimensionless PDEs (partial differential equations) are solved with the help of Finite Difference Scheme. In the presence of pertinent parameters, the precise movement of the flow in terms of velocity, temperature, entropy generation rate, and Bejan numbers are presented graphically, which are parabolic in nature. Streamline profiles are also presented, which exemplify the accurate movement of the flow. The current study is one of the infrequent contributions to the existing literature as previous studies have not attempted to solve the system of high order non-linear PDEs for the unsteady flow with entropy generation and Hall effects in a permeable rotating channel. It is expected that the current analysis would provide a platform for solving the system of nonlinear PDEs of the other unexplored models that are associated to the two-dimensional unsteady flow in a rotating channel.
基金partially supported by the Brazilian agencies CAPES,CNPqthe support from the grants CNPq/306308/2022-3+3 种基金CNPq Grant No.153635/2024-0FAPEMAFAPEMA/UNIVERSAL-06395/22,FAPEMA/APP-12256/22financed in part by the Coordenacao de Aperfeicoamento de Pessoal de Nível Superior—Brasil(CAPES)—Finance Code 001。
文摘In this article,we investigate the nonrelativistic quantum motion of a charged particle within a rotating frame,taking into account the Aharonov–Bohm(AB)effect and a uniform magnetic field.Our analysis entails the derivation of the equation of motion and the corresponding radial equation to describe the system.Solving the resulting radial equation enables us to determine the eigenvalues and eigenfunctions,providing a clear expression for the energy levels.Furthermore,our numerical analysis highlights the substantial influence of rotation on both energy levels and optical properties.Specifically,we evaluate the photoionization cross-section with and without the effects of rotation.To elucidate the impact of rotation on the photoionization process of the system,we present graphics that offer an appealing visualization of the intrinsic nature of the physics involved.
文摘In this work,we have investigated the rotating effect on the thermodynamic properties of a 2D quantum ring.Accordingly,we have considered the radial potential of a 2D quantum ring and solved the Schrödinger equation in the presence of the Aharonov-Bohm effect and a uniform magnetic field for the considered potential.According to the solution of the equation,we calculated the eigenvalues and eigenfunctions of the considered system.Using the calculated energy spectrum,we obtained the partition function and thermodynamic properties of the system,such as the mean energy,specific heat,entropy and free energy.Our results show that the rotating effect has a significant influence on the thermophysical properties of a 2D quantum ring.We also study other effects of the rotating term:(1)the effect of different values of rotating parameters,and(2)the effect of negative rotation on the thermodynamic properties of the system.Our results are discussed in detail.
基金National Natural Science Foundation of China under Grant Nos.10647116 and 10575140the China Postdoctoral Science Foundation under Grant No.2005037175
文摘The general relativistic frame dragging effect on the properties,such as the moments of inertia and the radiiof gyration of fast rotating neutron stars with a uniform strong magnetic field,is calculated accurate to the first orderin the uniform angular velocity.The results show that compared with the corresponding non-rotating static sphericalsymmetric neutron star with a weaker magnetic field,a fast rotating neutron star(millisecond pulsar)with a strongermagnetic field has a relative smaller moment of inertia and radius of gyration.
文摘We discussed the unsteady flow of an incompressible viscous fluid in a rotating parallel plate channel bounded on one side by a porous bed under the influence of a uniform transverse magnetic field taking hall current into account. The perturbations are created by a constant pressure gradient along the plates in addition to the non-torsional oscillations of the upper plate. The flow in the clean fluid region is governed by Navier-Stoke’s equations while in the porous bed the equations are based on Darcy-Lapwood model. The exact solutions of velocity in the clean fluid and the porous medium consist of steady state and transient state. The time required for the transient state to decay is evaluated in detail and ultimate quasi-steady state solution has been derived analytically and also its behaviour is computationally discussed with reference to different flow parameters. The shear stresses on the boundaries and the mass flux are also obtained analytically and their behaviour is computationally discussed.
文摘The thermodynamic features of the Reiner-Rivlin nanoliquid flow induced by a spinning disk are analyzed numerically.The non-homogeneous two-phase nanofluid model is considered to analyze the effect of nanoparticles on the thermodynamics of the Reiner-Rivlin nanomaterial,which also includes a temperature-dependent heat source(THS)and an exponential space-dependent heat source(ESHS).Further,the transfer of heat and mass is analyzed with velocity slip,volume fraction jump,and temperature jump boundary conditions.The finite difference method-based routine is used to solve the complicated differential equations formed after using the von-Karman similarity technique.Limiting cases of the present problem are found to be in good agreement with benchmarking studies.The relationship of the pertinent parameters with the heat and mass transport is scrutinized using correlation,which is further evaluated based on the probable error estimates.Multivariable models are fitted for the friction factor at the disk and heat transport,which accurately predict the dependent variables.The Reiner-Rivlin nanoliquid temperature is influenced comparatively more by the ESHS than by THS.The Nusselt number is decreased by the ESHS and THS,whereas the friction factor at the disk is predominantly decremented by the wall roughness aspect.The increment in the non-Newtonian characteristic of the liquid leads more fluid to drain away in the radial direction far from the disk compared with the fluid nearby the disk in the presence of the centrifugal force during rotation.The increased thermal and volume fraction slip lowers the nanoliquid temperature and nanoparticle volume fraction profiles.
基金Supported by the National Natural Science Foundation of China under Grant Nos 11175108,U1432119,1146114100,11205075,11375076 and 11475104the Shandong Natural Science Foundation under Grant No ZR2014AQ012the Foundation of Shandong University under Grant No 2015WHWLJH01
文摘Based on the equations of state from the relativistic mean field theory without and with the inclusion of strangeness-bearing hyperons, we study the dimensionless spin parameter j = cJ/（GM2） of uniformly rotat- ing neutron stars. It is shown that the maximum value of the spin parameter jmax of a neutron star rotating at the Keplerian frequency fK is .jmax - 0.7 when the star mass M 〉 0.SM⊙, which is sustained for various versions of equations of state without and with hyperons. The relationship between j and the scaled rotation frequency f /fK is found to be insensitive to the star mass or the adopted equation of state in the models without hyperons. However, the emergence of byperons in neutron stars will lead to an uncertainty of the spin parameter j, which in turn could generate a complexity in the theoretical study of the quasi-periodic oscillations observed in disk-accreting compact-star systems.
文摘In this paper, we make an initial value investigation of the unsteady flow of incompressible viscous fluid between two rigid non-conducting rotating parallel plates bounded by a porous medium under the influence of a uniform magnetic field of strength H0 inclined at an angle of inclination α with normal to the boundaries taking hall current into account. The perturbations are created by a constant pressure gradient along the plates in addition to the non-torsional oscillations of the upper plate while the lower plate is at rest. The flow in the porous medium is governed by the Brinkman’s equations. The exact solution of the velocity in the porous medium consists of steady state and transient state. The time required for the transient state to decay is evaluated in detail and the ultimate quasi-steady state solution has been derived analytically. Its behaviour is computationally discussed with reference to the various governing parameters. The shear stresses on the boundaries are also obtained analytically and their behaviour is computationally discussed.
文摘Objective To compare the preliminary clinical outcome between fixed platform and rotating high-flexion prosthesis following total knee replacement(TKR).Methods Form January 2007 to December 2009,68 patients with osteoarthritis of
基金financially supported by the National Natural Science Foundation of China(Nos.U1430104,51622207 and 51372228)the National Key Research and Development Program of China(No.2017YFB0701600)
文摘Volume effect has been extensively investigated in several families of solid electrolytes, i.e., expanding the skeleton lattice by bigger-size substitution favors the ionic conduction. However, this effect is not applicable in α-Li2SO4 and α-Na3PO4 based inorganic ionic plastic crystal electrolytes, a unique family of solid electrolytes. Here, it is proposed that the underlying rotational motion effect of polyanion, which is actually inhibited by the substitution of bigger-size polyanion in single-phase solid solution region and causes the unexpected lowering of the ionic conductivity instead, should need the more consideration. Furthermore, through utilizing the rotational motion effect of polyanion, it is given that a new explanation of the ionic conductivities of Li10MP2S12 （M = Si, Ge, Se） electrolytes deviating from the volume effect. These results inspire new vision of rationalization of the high-performance solid electrolytes by tuning the rotational motion effect of polyanion.
文摘Based on the surface elasticity theory of GurtinMurdoch, thermo-elastic fields within rotating nanoshafts with varying material properties subjected to a thermal field are explicitly examined. Accounting for the surface energy effect, the nonclassical boundary conditions are enforced in the cases of fixed-free and free-free conditions. The effects of variation of material properties, temperature of the environment, angular velocity, and radius of the outer radius on the radial displacement, hoop and radial stresses are investigated. In all performed studies, the role of the surface effect on the thermo-elastic field of the nanostructure is methodically discussed.
基金the support to this work from the Ministry of Science and Technology of China (2016YFE0205200)China Railway (2015Z003-B)Scientific Research Foundation of State Key Laboratory of Traction Power (2017TPL_T01)
文摘The rapid development of high-speed railway networks requires advanced methods for analysing vibration and sound radiation characteristics of a fast rotating train wheel subject to a vertical harmonic wheel-rail force. In order to consider the rotation of the wheel and at the same time increase the computational efficiency, a procedure is adapted in this paper taking advantage of the axial symmetry of the wheel. In this procedure, a recently developed 2.5D finite element method, which can consider wheel rotation but only requires a 2D mesh over a cross section containing the wheel axis, is used to calculate the vibration response of the wheel. Then, the vibration response of the wheel is taken as acoustic boundary condition and the 2.5D acoustic boundary element method, which only requires a 1D mesh over the boundary of the above cross section, is utilised to calculate the sound radiation of the wheel. These 2.5D methods and relevant programs are validated by comparing results from this procedure with those from conventional 3D analyses using commercial software. The comparison also demonstrates that these 2.5D methods have a much higher computational efficiency. Using the 2.5D methods, we study the wheel rotation speed influences on the factors including the vertical receptance of the wheel at wheel-rail contact point, sound pressure level at a pre-defined standard measurement point, radiated sound power level, directivity of the radia- tion, and contribution of each part of the wheel. It can be concluded that the wheel rotation speed splits most peaks of the vertical receptance at the wheel-rail contact point, sound pressure levels at the field, and the sound power level of the wheel into two peaks. The directivity and power contribution of the wheel are also significantly changed by the wheel rotation speed. Therefore, the rotation of a train wheel should be taken into account when calculating its vibration and sound radiation.
文摘This communiquéis opted to study the flow of nanofluid because of heated disk rotation subjected to the convective boundaries with chemical reaction of first order.Wherein Buongiorno’s model for nanofluids is used due to its wide range of applications and the rotating disk under investigation is permeable.Small magneto Reynolds parameter and boundary layer assumptions are carried out to formulate the problem.The system of nonlinear partial differential equations governing the flow problem is converted into the set of ordinary differential equations by using particular relations known as Von Karman transformations.The complicated set of coupled ordinary differential equations with complicated boundary conditions is set to solve by an analytical technique Homotopy Analysis Method(HAM).Whereby the results obtained by the aforementioned method are provided analytically and analyzed graphically.Also validation of the work is confirmed by providing comparison of previous works in tabular form.Effect of chemical reaction parameter on mass transfer rate is also highlighted tabularly for its increament.Nusselt and Sherwood numbers calculated and compared to the like literature and found in good agreement.
