In order to suppress the fast decrease of the transfer efficiency of magnetic resonance coupled wireless power transfer system(MRCWPTS) with distance increase,this paper investigates the impact factors of the system t...In order to suppress the fast decrease of the transfer efficiency of magnetic resonance coupled wireless power transfer system(MRCWPTS) with distance increase,this paper investigates the impact factors of the system transfer efficiency and is,then formulates a new efficiency optimal control method based on frequency control.Based upon this control method two optimal control schemes are designed to achieve transfer efficiency control of the system.Simulations and experiments show that the proposed efficiency optimal control method can effectively stabilize the system transfer efficiency in a certain range so as to successfully solve the subtle issue of transfer efficiency variation with distance.展开更多
The problem of the steady magnetohydrodynamic （MHD） stagnation-point flow of an incompressible viscous fluid over a stretching sheet is studied. The effect of an induced magnetic field is taken into account. The non...The problem of the steady magnetohydrodynamic （MHD） stagnation-point flow of an incompressible viscous fluid over a stretching sheet is studied. The effect of an induced magnetic field is taken into account. The nonlinear partial differential equations are transformed into ordinary differential equations via the similarity transformation. The transformed boundary layer equations are solved numerically using the shooting method. Numerical results are obtained for various magnetic parameters and Prandtl numbers. The effects of the induced magnetic field on the skin friction coefficient, the local Nusselt number, the velocity, and the temperature profiles are presented graphically and discussed in detail.展开更多
Kerosene-alumina nanofluid flow and heat transfer in the presence of magnetic field are studied. The basic partial differential equations are reduced to ordinary differential equations which are solved semi analytical...Kerosene-alumina nanofluid flow and heat transfer in the presence of magnetic field are studied. The basic partial differential equations are reduced to ordinary differential equations which are solved semi analytically using differential transformation method. Velocity and temperature profiles as well as the skin friction coefficient and the Nusselt number are determined analytically. The influence of pertinent parameters such as magnetic parameter, nanofluid volume fraction, viscosity parameter and Eckert number on the flow and heat transfer characteristics is discussed. Results indicate that skin friction coefficient decreases with increase of magnetic parameter, nanofluid volume fraction and viscosity parameter. Nusselt number increases with increase of magnetic parameter and nanofluid volume fraction while it decreases with increase of Eckert number and viscosity parameter.展开更多
This short review examines the most recent functional studies of the topographic organization of the human corpus callosum, the main interhemispheric commissure. After a brief description of its anatomy, development, ...This short review examines the most recent functional studies of the topographic organization of the human corpus callosum, the main interhemispheric commissure. After a brief description of its anatomy, development, microstructure, and function, it examines and discusses the latest findings obtained using diffusion tensor imaging(DTI) and tractography(DTT) and functional magnetic resonance imaging(f MRI), three recently developed imaging techniques that have significantly expanded and refined our knowledge of the commissure. While DTI and DTT have been providing insights into its microstructure, integrity and level of myelination, f MRI has been the key technique in documenting the activation of white matter fibers, particularly in the corpus callosum. By combining DTT and f MRI it has been possible to describe the trajectory of the callosal fibers interconnecting the primary olfactory, gustatory, motor, somatic sensory, auditory and visual cortices at sites where the activation elicited by peripheral stimulation was detected by fMRI. These studies have demonstrated the presence of callosal fiber tracts that cross the commissure at the level of the genu, body, and splenium, at sites showing f MRI activation. Altogether such findings lend further support to the notion that the corpus callosum displays a functional topographic organization that can be explored with f MRI.展开更多
This research entails the study of heat and mass transfer of nanofluid flow in a fluidized bed dryer used in tea drying processes in presence of induced magnetic field. A mathematical model describing the fluid flow i...This research entails the study of heat and mass transfer of nanofluid flow in a fluidized bed dryer used in tea drying processes in presence of induced magnetic field. A mathematical model describing the fluid flow in a Fluidized bed dryer was developed using the nonlinear partial differential equations. Due to their non-linearity, the equations were solved numerically by use of the finite difference method. The effects of physical flow parameters on velocity, temperature, concentration and magnetic induction profiles were studied and results were presented graphically. From the mathematical analysis, it was deduced that addition of silver nanoparticles into the fluid flow enhanced velocity and temperature profiles. This led to improved heat transfer in the fluidized bed dryer, hence amplifying the tea drying process. Furthermore, it was noted that induced magnetic field tends to decrease the fluid velocity, which results in uniform distribution of heat leading to efficient heat transfer between the tea particles and the fluid, thus improving the drying process. The research findings provide information to industries on ways to optimize thermal performance of fluidized bed dryers.展开更多
The electrochemical nitrate reduction reaction(NO_(3)RR)to ammonia under ambient conditions is a promising approach for addressing elevated nitrate levels in water bodies,but the progress of this reaction is impeded b...The electrochemical nitrate reduction reaction(NO_(3)RR)to ammonia under ambient conditions is a promising approach for addressing elevated nitrate levels in water bodies,but the progress of this reaction is impeded by the complex series of chemical reactions involving electron and proton transfer and competing hydrogen evolution reaction.Therefore,it becomes imperative to develop an electro-catalyst that exhibits exceptional efficiency and remarkable selectivity for ammonia synthesis while maintaining long-term stability.Herein the magnetic biochar(Fe-C)has been synthesized by a two-step mechanochemical route after a pyrolysis treatment(450,700,and 1000℃),which not only significantly decreases the particle size,but also exposes more oxygen-rich functional groups on the surface,promoting the adsorption of nitrate and water and accelerating electron transfer to convert it into ammonia.Results showed that the catalyst(Fe-C-700)has an impressive NH_(3)production rate of 3.5 mol·h^(−1)·gcat^(−1),high Faradaic efficiency of 88%,and current density of 0.37 A·cm^(−2)at 0.8 V vs.reversible hydrogen electrode(RHE).In-situ Fourier transform infrared spectroscopy(FTIR)is used to investigate the reaction intermediate and to monitor the reaction.The oxygen functionalities on the catalyst surface activate nitrate ions to form various intermediates(NO_(2),NO,NH_(2)OH,and NH_(2))and reduce the rate determining step energy barrier(*NO_(3)→*NO_(2)).This study presents a novel approach for the use of magnetic biochar as an electro-catalyst in NO_(3)RR and opens the road for solving environmental and energy challenges.展开更多
A parabolic trough solar collector(PTSC)converts solar radiation into thermal energy.However,low thermal efficiency of PTSC poses a hindrance to the deployment of solar thermal power plants.Thermal performance of PTSC...A parabolic trough solar collector(PTSC)converts solar radiation into thermal energy.However,low thermal efficiency of PTSC poses a hindrance to the deployment of solar thermal power plants.Thermal performance of PTSC is enhanced in this study by incorporating magnetic nanoparticles into the working fluid.The circular receiver pipe,with dimensions of 66 mm diameter,2 mm thickness,and 24 m length,is exposed to uniform temperature and velocity conditions.The working fluid,Therminol-66,is supplemented with Fe3O4 magnetic nanoparticles at concentrations ranging from 1%to 4%.The findings demonstrate that the inclusion of nanoparticles increases the convective heat transfer coefficient(HTC)of the PTSC,with higher nanoparticle volume fractions leading to greater heat transfer but increased pressure drop.The thermal enhancement factor(TEF)of the PTSC is positively affected by the volume fraction of nanoparticles,both with and without a magnetic field.Notably,the scenario with a 4%nanoparticle volume fraction and a magnetic field strength of 250 G exhibits the highest TEF,indicating superior thermal performance.These findings offer potential avenues for improving the efficiency of PTSCs in solar thermal plants by introducing magnetic nanoparticles into the working fluid.展开更多
Magnetohydrodynamic behaviors in a resistance spot weld nugget under different welding currents are investigated based on a multiphysics coupled numerical model, which incorporates phase change and variable electrical...Magnetohydrodynamic behaviors in a resistance spot weld nugget under different welding currents are investigated based on a multiphysics coupled numerical model, which incorporates phase change and variable electrical contact resis-tances at faying surface and electrode-workpiece contact surface. The patterns of the flow field and thermal field at the end of the welding phase under different welding currents are obtained. The evolutions of fluid flow and heat transfer during the whole welding process are also revealed systematically. The analysis results are also compared with a traditional electrothermal coupled model to obtain the quantitative effects of the magnetohydrodynamic behaviors on the resistance spot weld nugget formation.展开更多
Traditional power supply method for moving electric railway vehicles is based on contact type power collection technology.This sometimes cannot meet the requirements of modern rail transportation.A new wireless power ...Traditional power supply method for moving electric railway vehicles is based on contact type power collection technology.This sometimes cannot meet the requirements of modern rail transportation.A new wireless power transfer(WPT)technology can offer significant benefits in modern rail transportation particularly in some stringent environments.This paper reviews the status and the development of rail transit power supply technology,and introduces a new challenging technology--inductive power transfer(IPT)technology for rail transit.Tesla established the underpinning of IPT technology and creatively and significantly demonstrated power transfer by using highly resonant tuned coils long time ago.However,only in recent years the IPT technology has been significantly improved including the transfer air-gap length,transfer efficiency,coupling factor,power transfer capability and so on.This is mainly due to innovative semiconductor switches,higher control frequency,better coil designs and high performance material,new track and vehicle construction techniques.Recent advances in IPT for rail transit and major milestones of the developments are summarized in this paper.Some important technical issues such as coupling coil structures,power supply schemes,segmentation switching techniques for long-distance power supply,and bidirectional IPT systems for braking energy feedback are discussed.展开更多
Background:Lymphedema is a debilitating condition that frequently occurs after breast cancer treatment.Vas-cularized lymph node transfer(VLNT)is a promising approach to reduce lymphedema.This study used magnetic reson...Background:Lymphedema is a debilitating condition that frequently occurs after breast cancer treatment.Vas-cularized lymph node transfer(VLNT)is a promising approach to reduce lymphedema.This study used magnetic resonance lymphangiography(MRL)to assess lymphatic reconnections post-VLNT in patients with breast cancer-related lymphedema(BCRL).Methods:The clinical records of six female patients with unilateral upper limb BCRL who underwent VLNT(4 cases)or VLNT combined with breast reconstruction(2 cases)were retrospectively reviewed.All patients were examined using MRL preoperatively and at the 1-year follow-up.The morphological characteristics of the lymphatic network,dermal backflow patterns,and architecture of the lymph nodes were evaluated.Clinical outcomes,patient satisfaction,and complications were assessed.Results:At the 1-year follow-up,reduction in tissue edema and limb circumference was achieved in all six patients.In MRL,the implanted lymph nodes in the axillary region of the affected upper arm were enhanced and visualized in all six patients.Reconnected lymphatic vessels in the subcutaneous tissue associated with the implanted lymph nodes were observed in four patients.Decreased dermal backflow and lymphatic vessel dilation of the affected limbs were observed in all six patients.No disruption of the lymph flow in the donor area was detected.Conclusion:This is the first study to provide direct imaging evidence for the reconnection of afferent lymphatic channels between implanted lymph nodes and the recipient lymphatic system in patients with BCRL.Overall,our study demonstrates the mechanism and efficacy of VLNT in reducing lymphedema.展开更多
文摘In order to suppress the fast decrease of the transfer efficiency of magnetic resonance coupled wireless power transfer system(MRCWPTS) with distance increase,this paper investigates the impact factors of the system transfer efficiency and is,then formulates a new efficiency optimal control method based on frequency control.Based upon this control method two optimal control schemes are designed to achieve transfer efficiency control of the system.Simulations and experiments show that the proposed efficiency optimal control method can effectively stabilize the system transfer efficiency in a certain range so as to successfully solve the subtle issue of transfer efficiency variation with distance.
基金supported by the Fundamental Research Grant Scheme (FRGS) of the Ministry of Higher Education (MOHE) of Malaysia (No. UKM-ST-07-FRGS0036-2009)
文摘The problem of the steady magnetohydrodynamic （MHD） stagnation-point flow of an incompressible viscous fluid over a stretching sheet is studied. The effect of an induced magnetic field is taken into account. The nonlinear partial differential equations are transformed into ordinary differential equations via the similarity transformation. The transformed boundary layer equations are solved numerically using the shooting method. Numerical results are obtained for various magnetic parameters and Prandtl numbers. The effects of the induced magnetic field on the skin friction coefficient, the local Nusselt number, the velocity, and the temperature profiles are presented graphically and discussed in detail.
文摘Kerosene-alumina nanofluid flow and heat transfer in the presence of magnetic field are studied. The basic partial differential equations are reduced to ordinary differential equations which are solved semi analytically using differential transformation method. Velocity and temperature profiles as well as the skin friction coefficient and the Nusselt number are determined analytically. The influence of pertinent parameters such as magnetic parameter, nanofluid volume fraction, viscosity parameter and Eckert number on the flow and heat transfer characteristics is discussed. Results indicate that skin friction coefficient decreases with increase of magnetic parameter, nanofluid volume fraction and viscosity parameter. Nusselt number increases with increase of magnetic parameter and nanofluid volume fraction while it decreases with increase of Eckert number and viscosity parameter.
基金Supported by Ministero Istruzione,Universitàe Ricerca(MIURPRIN 2007,2009)
文摘This short review examines the most recent functional studies of the topographic organization of the human corpus callosum, the main interhemispheric commissure. After a brief description of its anatomy, development, microstructure, and function, it examines and discusses the latest findings obtained using diffusion tensor imaging(DTI) and tractography(DTT) and functional magnetic resonance imaging(f MRI), three recently developed imaging techniques that have significantly expanded and refined our knowledge of the commissure. While DTI and DTT have been providing insights into its microstructure, integrity and level of myelination, f MRI has been the key technique in documenting the activation of white matter fibers, particularly in the corpus callosum. By combining DTT and f MRI it has been possible to describe the trajectory of the callosal fibers interconnecting the primary olfactory, gustatory, motor, somatic sensory, auditory and visual cortices at sites where the activation elicited by peripheral stimulation was detected by fMRI. These studies have demonstrated the presence of callosal fiber tracts that cross the commissure at the level of the genu, body, and splenium, at sites showing f MRI activation. Altogether such findings lend further support to the notion that the corpus callosum displays a functional topographic organization that can be explored with f MRI.
文摘This research entails the study of heat and mass transfer of nanofluid flow in a fluidized bed dryer used in tea drying processes in presence of induced magnetic field. A mathematical model describing the fluid flow in a Fluidized bed dryer was developed using the nonlinear partial differential equations. Due to their non-linearity, the equations were solved numerically by use of the finite difference method. The effects of physical flow parameters on velocity, temperature, concentration and magnetic induction profiles were studied and results were presented graphically. From the mathematical analysis, it was deduced that addition of silver nanoparticles into the fluid flow enhanced velocity and temperature profiles. This led to improved heat transfer in the fluidized bed dryer, hence amplifying the tea drying process. Furthermore, it was noted that induced magnetic field tends to decrease the fluid velocity, which results in uniform distribution of heat leading to efficient heat transfer between the tea particles and the fluid, thus improving the drying process. The research findings provide information to industries on ways to optimize thermal performance of fluidized bed dryers.
基金the National Natural Science Foundation of China(Nos.52072152 and 51802126)the Jiangsu University Jinshan Professor Fund,the Jiangsu Specially-Appointed Professor Fund,Open Fund from Guangxi Key Laboratory of Electrochemical Energy Materials,Zhenjiang“Jinshan Talents”Project 2021,China PostDoctoral Science Foundation(No.2022M721372)+3 种基金“Doctor of Entrepreneurship and Innovation”in Jiangsu Province(No.JSSCBS20221197)the Postgraduate Research&Practice Innovation Program of Jiangsu Province(No.KYCX22_3645)the National Natural Science Foundation of China(No.22208134)Jiangsu Agricultural Science and Technology Innovation Fund(No.CX(21)1010).
文摘The electrochemical nitrate reduction reaction(NO_(3)RR)to ammonia under ambient conditions is a promising approach for addressing elevated nitrate levels in water bodies,but the progress of this reaction is impeded by the complex series of chemical reactions involving electron and proton transfer and competing hydrogen evolution reaction.Therefore,it becomes imperative to develop an electro-catalyst that exhibits exceptional efficiency and remarkable selectivity for ammonia synthesis while maintaining long-term stability.Herein the magnetic biochar(Fe-C)has been synthesized by a two-step mechanochemical route after a pyrolysis treatment(450,700,and 1000℃),which not only significantly decreases the particle size,but also exposes more oxygen-rich functional groups on the surface,promoting the adsorption of nitrate and water and accelerating electron transfer to convert it into ammonia.Results showed that the catalyst(Fe-C-700)has an impressive NH_(3)production rate of 3.5 mol·h^(−1)·gcat^(−1),high Faradaic efficiency of 88%,and current density of 0.37 A·cm^(−2)at 0.8 V vs.reversible hydrogen electrode(RHE).In-situ Fourier transform infrared spectroscopy(FTIR)is used to investigate the reaction intermediate and to monitor the reaction.The oxygen functionalities on the catalyst surface activate nitrate ions to form various intermediates(NO_(2),NO,NH_(2)OH,and NH_(2))and reduce the rate determining step energy barrier(*NO_(3)→*NO_(2)).This study presents a novel approach for the use of magnetic biochar as an electro-catalyst in NO_(3)RR and opens the road for solving environmental and energy challenges.
文摘A parabolic trough solar collector(PTSC)converts solar radiation into thermal energy.However,low thermal efficiency of PTSC poses a hindrance to the deployment of solar thermal power plants.Thermal performance of PTSC is enhanced in this study by incorporating magnetic nanoparticles into the working fluid.The circular receiver pipe,with dimensions of 66 mm diameter,2 mm thickness,and 24 m length,is exposed to uniform temperature and velocity conditions.The working fluid,Therminol-66,is supplemented with Fe3O4 magnetic nanoparticles at concentrations ranging from 1%to 4%.The findings demonstrate that the inclusion of nanoparticles increases the convective heat transfer coefficient(HTC)of the PTSC,with higher nanoparticle volume fractions leading to greater heat transfer but increased pressure drop.The thermal enhancement factor(TEF)of the PTSC is positively affected by the volume fraction of nanoparticles,both with and without a magnetic field.Notably,the scenario with a 4%nanoparticle volume fraction and a magnetic field strength of 250 G exhibits the highest TEF,indicating superior thermal performance.These findings offer potential avenues for improving the efficiency of PTSCs in solar thermal plants by introducing magnetic nanoparticles into the working fluid.
基金the National Natural Science Foundation of China (Grant Nos. 50705059 and 50575140)National Basic Research Program of China (Grant No. 2006CB705400)
文摘Magnetohydrodynamic behaviors in a resistance spot weld nugget under different welding currents are investigated based on a multiphysics coupled numerical model, which incorporates phase change and variable electrical contact resis-tances at faying surface and electrode-workpiece contact surface. The patterns of the flow field and thermal field at the end of the welding phase under different welding currents are obtained. The evolutions of fluid flow and heat transfer during the whole welding process are also revealed systematically. The analysis results are also compared with a traditional electrothermal coupled model to obtain the quantitative effects of the magnetohydrodynamic behaviors on the resistance spot weld nugget formation.
基金This work was supported in part by the National Key R&D Program of China under Grant 2017YFB1201003.
文摘Traditional power supply method for moving electric railway vehicles is based on contact type power collection technology.This sometimes cannot meet the requirements of modern rail transportation.A new wireless power transfer(WPT)technology can offer significant benefits in modern rail transportation particularly in some stringent environments.This paper reviews the status and the development of rail transit power supply technology,and introduces a new challenging technology--inductive power transfer(IPT)technology for rail transit.Tesla established the underpinning of IPT technology and creatively and significantly demonstrated power transfer by using highly resonant tuned coils long time ago.However,only in recent years the IPT technology has been significantly improved including the transfer air-gap length,transfer efficiency,coupling factor,power transfer capability and so on.This is mainly due to innovative semiconductor switches,higher control frequency,better coil designs and high performance material,new track and vehicle construction techniques.Recent advances in IPT for rail transit and major milestones of the developments are summarized in this paper.Some important technical issues such as coupling coil structures,power supply schemes,segmentation switching techniques for long-distance power supply,and bidirectional IPT systems for braking energy feedback are discussed.
基金supported by the National Natural Science Foundation of China(grant nos.81372080 and 82302822)Shanghai Municipal Key Clinical Specialty(grant no.shslczdzk00901)Shanghai Sailing Program(grant no.21YF1424000).
文摘Background:Lymphedema is a debilitating condition that frequently occurs after breast cancer treatment.Vas-cularized lymph node transfer(VLNT)is a promising approach to reduce lymphedema.This study used magnetic resonance lymphangiography(MRL)to assess lymphatic reconnections post-VLNT in patients with breast cancer-related lymphedema(BCRL).Methods:The clinical records of six female patients with unilateral upper limb BCRL who underwent VLNT(4 cases)or VLNT combined with breast reconstruction(2 cases)were retrospectively reviewed.All patients were examined using MRL preoperatively and at the 1-year follow-up.The morphological characteristics of the lymphatic network,dermal backflow patterns,and architecture of the lymph nodes were evaluated.Clinical outcomes,patient satisfaction,and complications were assessed.Results:At the 1-year follow-up,reduction in tissue edema and limb circumference was achieved in all six patients.In MRL,the implanted lymph nodes in the axillary region of the affected upper arm were enhanced and visualized in all six patients.Reconnected lymphatic vessels in the subcutaneous tissue associated with the implanted lymph nodes were observed in four patients.Decreased dermal backflow and lymphatic vessel dilation of the affected limbs were observed in all six patients.No disruption of the lymph flow in the donor area was detected.Conclusion:This is the first study to provide direct imaging evidence for the reconnection of afferent lymphatic channels between implanted lymph nodes and the recipient lymphatic system in patients with BCRL.Overall,our study demonstrates the mechanism and efficacy of VLNT in reducing lymphedema.
