The steady, laminar, incompressible and two dimensional micropolar flow between two porous disks was investigated using optimal homotopy asymptotic method(OHAM) and fourth order Runge–Kutta numerical method. Comparis...The steady, laminar, incompressible and two dimensional micropolar flow between two porous disks was investigated using optimal homotopy asymptotic method(OHAM) and fourth order Runge–Kutta numerical method. Comparison between OHAM and numerical method shows that OHAM is an exact and high efficient method for solving these kinds of problems. The results are presented to study the velocity and rotation profiles for different physical parameters such as Reynolds number, vortex viscosity parameter, spin gradient viscosity and microinertia density parameter. As an important outcome, the magnitude of the microrotation increases with an increase in the values of injection velocity while it decreases by increasing the values of suction velocity.展开更多
Aimed at the difficulty in revealing the vibration localization mechanism of mistuned bladed disks by using simple non-linear model,a mechanical model of the bladed disk with random mistuning of hysteretic dry frictio...Aimed at the difficulty in revealing the vibration localization mechanism of mistuned bladed disks by using simple non-linear model,a mechanical model of the bladed disk with random mistuning of hysteretic dry friction damping was established.Then,the incremental harmonic balance method was used to analyze the effects of the parameters of bladed disks,such as the mistuning strength of dry friction force,coupled strength,viscous damping ratio and friction strength,on the forced response of the bladed disks.The results show that the vibrational energy localization phenomenon turns up in the tuned bladed disks if the nonlinear friction damping exists,and the random mistuning of the dry friction force intensifies this kind of vibration localization.展开更多
Metal-organic framework(MOF)nanostructures have emerged as a prominent class of materials in the advancement of electrochemical sensors.The rational design of bimetallic MOF-functionalized microelectrode is of importa...Metal-organic framework(MOF)nanostructures have emerged as a prominent class of materials in the advancement of electrochemical sensors.The rational design of bimetallic MOF-functionalized microelectrode is of importance for improv-ing the electrochemical performance but still in great challenge.In this work,the bimetallic FeCo-MOF nanostructures were assembled onto a gold disk ultramicroelectrode(Au UME,5.2μm in diameter)via an in-situ electrodeposition method,which enhanced the sensitive detection of epinephrine(EP).The in-situ electrodeposited FeCo-MOF exhibited a character-istic nanoflower-like morphology and was uniformly dispersed on the Au UME.The FeCo-MOF/Au UME demonstrated excellent electrochemical performance on the detection of EP with a high sensitivity of 36.93μA·μmol^(-1)·L·cm^(-2)and a low detection limit of 1.28μmol·L^(-1).It can be attributed to the nonlinear diffusion of EP onto the ultra-micro working substrate,coupled with synergistical catalytic activity of the bimetallic Fe,Co within MOF structure.Furthermore,the FeCo-MOF/Au UME has been successful applied to the analysis of EP in human serum samples,yielding high recovery rates.These results not only contribute to the expansion of the research area of electrochemical sensors,but also provide novel insights and directions into the development of high-performance MOF-based electrochemical sensors.展开更多
对美国3M公司的锶特效固相萃取片(EmporeTMStrontium Rad Disk)分离水溶液中锶离子的性能进行了系统研究,包括酸度、流速、样品体积对吸附百分比的影响,吸附容量的测定,137 Cs和99 Tc在萃取片上的吸附情况等,并对萃取片上90Sr的解吸及片...对美国3M公司的锶特效固相萃取片(EmporeTMStrontium Rad Disk)分离水溶液中锶离子的性能进行了系统研究,包括酸度、流速、样品体积对吸附百分比的影响,吸附容量的测定,137 Cs和99 Tc在萃取片上的吸附情况等,并对萃取片上90Sr的解吸及片上90Sr的放射性测量进行了研究。在此基础上,给出了萃取片法分析环境水中90Sr的推荐程序。样品体积为1L,液闪测量时间为1h时,分析程序的最小可探测活度浓度为0.033Bq/L。最后应用一些实际环境水样对该程序进行了检验。展开更多
Mechanical behaviors of granular materials are complicated and greatly influenced by the particle shape.Current,some composite approaches have been proposed for realistic particle shape modelling within discrete eleme...Mechanical behaviors of granular materials are complicated and greatly influenced by the particle shape.Current,some composite approaches have been proposed for realistic particle shape modelling within discrete element method(DEM),while they cannot give a good representation to the shape and mass properties of a real particle.In this work,a novel algorithm is developed to model an arbitrary particle using a cluster of non-overlapping disks.The algorithm mainly consists of two components:boundary filling and domain filling.In the boundary filling,some disks are placed along the boundary for a precise representation of the particle shape,and some more disks are placed in the domain to give an approximation to the mass properties of the particle in the domain filling.Besides,a simple method is proposed to correct the mass properties of a cluster after domain filling and reduce the number of the disks in a cluster for lower computational load.Moreover,it is another great merit of the algorithm that a cluster generated by the algorithm can be used to simulate the particle breakage because of no overlaps between the disks in a cluster.Finally,several examples are used to show the robust performance of the algorithm.A current FORTRAN version of the algorithm is available by contacting the author.展开更多
The primary goal of this study is to examine the flow of non-Newtonian Sutterby fluid conveying tiny particles as well as the induced magnetic field in the involvement of motile gyrotactic microorganisms.The flow is c...The primary goal of this study is to examine the flow of non-Newtonian Sutterby fluid conveying tiny particles as well as the induced magnetic field in the involvement of motile gyrotactic microorganisms.The flow is configured between a pair of circular disks filled with Sutterby fluid conveying tiny particles and gyrotactic microorganisms.The impact of Arrhenius kinetics and thermal radiation is also considered in the governing flow.The presented mathematical models are modified into nonlinear ordinary differential equations using the relevant similarity transformations.To compute the numerical solutions of nonlinear ordinary differential equations,the differential transform procedure(DTM)is used.For nonlinear problems,integral transform techniques are more difficult to execute.However,a polynomial solution is obtained as an analytical solution using the differential transform method,which is based on Taylor expansion.To improve the convergence of the formulated mathematical modeling,the Padéapproximation was combined with the differential transformation method.Variations of different dimensionless factors are discussed for velocity,temperature field,concentration distribution,and motile gyrotactic microorganism profile.Torque on both plates is calculated and presented through tables.展开更多
Head disk collision models of 'coefficient-of-restitution' are widely used in the head disk interface simulation. A new head disk collision model called 'critical velocity model' has been developed. Nu...Head disk collision models of 'coefficient-of-restitution' are widely used in the head disk interface simulation. A new head disk collision model called 'critical velocity model' has been developed. Numerical simulation of dynamics of a typical Winchester-type slider is presented under the influence of head disk collisions due to disk surface defects such as localize asperities. Two kinds of head disk collision models have been compared and analysed. The results show that the critical velocity is a very important parameter which affects the dynamics of the slider.展开更多
文摘The steady, laminar, incompressible and two dimensional micropolar flow between two porous disks was investigated using optimal homotopy asymptotic method(OHAM) and fourth order Runge–Kutta numerical method. Comparison between OHAM and numerical method shows that OHAM is an exact and high efficient method for solving these kinds of problems. The results are presented to study the velocity and rotation profiles for different physical parameters such as Reynolds number, vortex viscosity parameter, spin gradient viscosity and microinertia density parameter. As an important outcome, the magnitude of the microrotation increases with an increase in the values of injection velocity while it decreases by increasing the values of suction velocity.
基金Project(2007CB707706) supported by the National Basic Research Program of China
文摘Aimed at the difficulty in revealing the vibration localization mechanism of mistuned bladed disks by using simple non-linear model,a mechanical model of the bladed disk with random mistuning of hysteretic dry friction damping was established.Then,the incremental harmonic balance method was used to analyze the effects of the parameters of bladed disks,such as the mistuning strength of dry friction force,coupled strength,viscous damping ratio and friction strength,on the forced response of the bladed disks.The results show that the vibrational energy localization phenomenon turns up in the tuned bladed disks if the nonlinear friction damping exists,and the random mistuning of the dry friction force intensifies this kind of vibration localization.
基金support from the National Key Research and Development Program of China(2021YFB3201400,2021YFB3201401,2020YFC1908602)the National Natural Science Foundation of China(21904001 and 61774159)+1 种基金the Anhui Provincial Natural Science Foundation(2008085QF288)the Scientific Research Foundation for the Returned Overseas Chinese Scholars,Anhui Province(2020LCX032).
文摘Metal-organic framework(MOF)nanostructures have emerged as a prominent class of materials in the advancement of electrochemical sensors.The rational design of bimetallic MOF-functionalized microelectrode is of importance for improv-ing the electrochemical performance but still in great challenge.In this work,the bimetallic FeCo-MOF nanostructures were assembled onto a gold disk ultramicroelectrode(Au UME,5.2μm in diameter)via an in-situ electrodeposition method,which enhanced the sensitive detection of epinephrine(EP).The in-situ electrodeposited FeCo-MOF exhibited a character-istic nanoflower-like morphology and was uniformly dispersed on the Au UME.The FeCo-MOF/Au UME demonstrated excellent electrochemical performance on the detection of EP with a high sensitivity of 36.93μA·μmol^(-1)·L·cm^(-2)and a low detection limit of 1.28μmol·L^(-1).It can be attributed to the nonlinear diffusion of EP onto the ultra-micro working substrate,coupled with synergistical catalytic activity of the bimetallic Fe,Co within MOF structure.Furthermore,the FeCo-MOF/Au UME has been successful applied to the analysis of EP in human serum samples,yielding high recovery rates.These results not only contribute to the expansion of the research area of electrochemical sensors,but also provide novel insights and directions into the development of high-performance MOF-based electrochemical sensors.
文摘对美国3M公司的锶特效固相萃取片(EmporeTMStrontium Rad Disk)分离水溶液中锶离子的性能进行了系统研究,包括酸度、流速、样品体积对吸附百分比的影响,吸附容量的测定,137 Cs和99 Tc在萃取片上的吸附情况等,并对萃取片上90Sr的解吸及片上90Sr的放射性测量进行了研究。在此基础上,给出了萃取片法分析环境水中90Sr的推荐程序。样品体积为1L,液闪测量时间为1h时,分析程序的最小可探测活度浓度为0.033Bq/L。最后应用一些实际环境水样对该程序进行了检验。
基金Project(2011CB013504)supported by the National Basic Research Program(973 Program)of ChinaProject(2013BAB06B01)supported by Key Projects in the National Science&Technology Pillar Program during the Twelfth Five-year Plan Period,China+1 种基金Projects(51309089,51479049)supported by National Natural Science Foundation of ChinaProject(487237)supported by Natural Sciences and Engineering Research Council of Canada
文摘Mechanical behaviors of granular materials are complicated and greatly influenced by the particle shape.Current,some composite approaches have been proposed for realistic particle shape modelling within discrete element method(DEM),while they cannot give a good representation to the shape and mass properties of a real particle.In this work,a novel algorithm is developed to model an arbitrary particle using a cluster of non-overlapping disks.The algorithm mainly consists of two components:boundary filling and domain filling.In the boundary filling,some disks are placed along the boundary for a precise representation of the particle shape,and some more disks are placed in the domain to give an approximation to the mass properties of the particle in the domain filling.Besides,a simple method is proposed to correct the mass properties of a cluster after domain filling and reduce the number of the disks in a cluster for lower computational load.Moreover,it is another great merit of the algorithm that a cluster generated by the algorithm can be used to simulate the particle breakage because of no overlaps between the disks in a cluster.Finally,several examples are used to show the robust performance of the algorithm.A current FORTRAN version of the algorithm is available by contacting the author.
文摘The primary goal of this study is to examine the flow of non-Newtonian Sutterby fluid conveying tiny particles as well as the induced magnetic field in the involvement of motile gyrotactic microorganisms.The flow is configured between a pair of circular disks filled with Sutterby fluid conveying tiny particles and gyrotactic microorganisms.The impact of Arrhenius kinetics and thermal radiation is also considered in the governing flow.The presented mathematical models are modified into nonlinear ordinary differential equations using the relevant similarity transformations.To compute the numerical solutions of nonlinear ordinary differential equations,the differential transform procedure(DTM)is used.For nonlinear problems,integral transform techniques are more difficult to execute.However,a polynomial solution is obtained as an analytical solution using the differential transform method,which is based on Taylor expansion.To improve the convergence of the formulated mathematical modeling,the Padéapproximation was combined with the differential transformation method.Variations of different dimensionless factors are discussed for velocity,temperature field,concentration distribution,and motile gyrotactic microorganism profile.Torque on both plates is calculated and presented through tables.
文摘Head disk collision models of 'coefficient-of-restitution' are widely used in the head disk interface simulation. A new head disk collision model called 'critical velocity model' has been developed. Numerical simulation of dynamics of a typical Winchester-type slider is presented under the influence of head disk collisions due to disk surface defects such as localize asperities. Two kinds of head disk collision models have been compared and analysed. The results show that the critical velocity is a very important parameter which affects the dynamics of the slider.
