The Parallel-Plate Flow Chamber （PPFC）, of which the height is far smaller than its own length and width, is one of the main apparatus for the in-vitro study of the mechanical behavior of cultured vascular Endotheli...The Parallel-Plate Flow Chamber （PPFC）, of which the height is far smaller than its own length and width, is one of the main apparatus for the in-vitro study of the mechanical behavior of cultured vascular Endothelical Cells （ECs） exposed to fluid shear stress. The steady flow in different kinds of PPFC has been extensively investigated, whereas, the pulsatile flow in the PPFC has received little attention. In consideration of the characteristics of geometrical size and pulsatile flow in the PPFC, the 3-D pulsatile flow was decomposed into a 2-D pulsatile flow in the vertical plane, and an incompressible plane potential flow in the horizontal plane. A simple method was then proposed to analyze the pulsatile flow in the PPFC with spatial shear stress gradient. On the basis of the method, the pulsatile fluid shear stresses in several reported PPFCs with spatial shear stress gradients were calculated. The results were theoretically meaningful for applying the PPFCs in-vitro, to simulate the pulsatile fluid shear stress environment, to which cultured ECs were exposed.展开更多
This paper compares the fluid flow phenomena occurring within a fractured reservoir for three different fracture models using computational fluid dynamics.The effect of the fracture-matrix interface condition is studi...This paper compares the fluid flow phenomena occurring within a fractured reservoir for three different fracture models using computational fluid dynamics.The effect of the fracture-matrix interface condition is studied on the pressure and velocity distribution.The fracture models were compared based on the variation in pressure and permeability conditions.The model was developed for isotropic and anisotropic permeability conditions.The results suggest that the fracture aperture can have a drastic effect on fluid flow.The porous fracture-matrix interface condition produces more realistic transport of fluids.By increasing the permeability in the isotropic porous matrix,the pressure drop was significantly higher in both the fracture and reservoir region.Under anisotropic conditions in the 3D fractured reservoir,the effect of the higher longitudinal permeability was found to lower the pressure in the fractured reservoir.Depending on the properties of the fractured reservoir,this study can enhance the understanding of fracture-matrix fluid interaction and provide a method for production optimisation.展开更多
An exploratory multinuclear magnetic resonance(MR)and magnetic resonance imaging(MRI)study was performed on lithium-ion battery cells with ^(7)Li,^(19)F,and ^(1)H measurements.A variable field superconducting magnet w...An exploratory multinuclear magnetic resonance(MR)and magnetic resonance imaging(MRI)study was performed on lithium-ion battery cells with ^(7)Li,^(19)F,and ^(1)H measurements.A variable field superconducting magnet with a fixed frequency parallel-plate radiofrequency(RF)probe was employed in the study.The magnetic field was changed to set the resonance frequency of each nucleus to the fixed RF probe frequency of 33.7 MHz.Two cartridge-like lithium-ion cells,with graphite anodes and LiNi_(0.5)Mn_(0.3)Co_(0.2)O_(2)(NMC)cathodes,were interrogated.One cell was pristine,and one was charged to a cell voltage of 4.2 V.The results presented demonstrate the great potential of the variable field magnet approach in multinuclear measurement of lithium-ion batteries.These methods open the door for developing faster and simpler methods for detecting,quantifying,and interpreting MR and MRI data from lithium-ion and other batteries.展开更多
The transient feeding to parallel-plate transmission lines from coaxial line is optimized by using the Finite-Difference Time-Domain (FDTD) method and a simple FDTD feed model. Observing the reflected voltages, this l...The transient feeding to parallel-plate transmission lines from coaxial line is optimized by using the Finite-Difference Time-Domain (FDTD) method and a simple FDTD feed model. Observing the reflected voltages, this letter presents the optimal feeding position and ratio of width to height for a given input impedance of the coaxial line.展开更多
Quartz crystal resonators are typical piezoelectric acoustic wave devices for frequency control applications with mechanical vibration frequency at the radio-frequency （RF） range. Precise analyses of the vibration a...Quartz crystal resonators are typical piezoelectric acoustic wave devices for frequency control applications with mechanical vibration frequency at the radio-frequency （RF） range. Precise analyses of the vibration and deformation are generally required in the resonator design and improvement process. The considerations include the presence of electrodes, mountings, bias fields such as temperature, initial stresses, and acceleration. Naturally, the finite element method is the only effective tool for such a coupled problem with multi-physics nature. The main challenge is the extremely large size of resulted linear equations. For this reason, we have been employing the Mindlin plate equations to reduce the computational difficulty. In addition, we have to utilize the parallel computing techniques on Linux clusters, which are widely available for academic and industrial applications nowadays, to improve the computing efficiency. The general principle of our research is to use open source software components and public domain technology to reduce cost for developers and users on a Linux cluster. We start with a mesh generator specifically for quartz crystal resonators of rectangular and circular types, and the Mindlin plate equations are implemented for the finite element analysis. Computing techniques like parallel processing, sparse matrix handling, and the latest eigenvalue extraction package are integrated into the program. It is clear from our computation that the combination of these algorithms and methods on a cluster can meet the memory requirement and reduce computing time significantly.展开更多
We explore the use of the parallel-plate resonator for the study of thin cuboid samples over a wide range of magnetic resonance frequencies.The parallel-plate resonator functions at frequencies from tens to hundreds o...We explore the use of the parallel-plate resonator for the study of thin cuboid samples over a wide range of magnetic resonance frequencies.The parallel-plate resonator functions at frequencies from tens to hundreds of MHz.Seven parallel-plate resonators are presented and discussed in a frequency range from 8 to 500 MHz.Magnetic resonance experiments were performed on both horizontal and vertical bore magnet systems with lithium and hydrogen nuclei.Parallel-plate radiofrequency(RF)probes are easy to build and easy to optimize.Experiments and simulations showed good sensitivity of the parallel-plate RF probe geometry with a small decrease in sensitivity at higher frequencies.展开更多
A comprehensive dynamic model consisting of 66 reactions and 24 species is developed to investigate the dynamic characteristics of ozone generation by positive pulsed dielectric barrier discharge（DBD） using parallel...A comprehensive dynamic model consisting of 66 reactions and 24 species is developed to investigate the dynamic characteristics of ozone generation by positive pulsed dielectric barrier discharge（DBD） using parallel-plate reactor in air.The electron energy conservation equation is coupled to the electron continuity equation,the heavy species continuity equation,and Poisson＇s equation for a better description.The reliability of the model is experimentally confirmed.The model can be used to predict the temporal and spatial evolution of species,as well as streamer propagation.The simulation results show that electron density increases nearly exponentially in the direction to the anode at the electron avalanche.Streamer propagation velocity is about 5.26×104m/s from anode to cathode in the simulated condition.The primary positive ion,negative ion,and excited species are O_2~＋,O_3^-and O_2（1？g） in pulsed DBD in air,respectively.N_2 O has the largest density among nitrogen oxides.e and N_2~＋densities in the streamer head increase gradually to maximum values with the development of the streamer.Meanwhile,the O_2~＋,O,O_3,N_2（A^3Σ） and N_2 O densities reach maximum values in the vicinity of the anode.展开更多
基金Project supported by the National Natural Science Foundation of China (Grant Nos. 10472027, 30670511).
文摘The Parallel-Plate Flow Chamber （PPFC）, of which the height is far smaller than its own length and width, is one of the main apparatus for the in-vitro study of the mechanical behavior of cultured vascular Endothelical Cells （ECs） exposed to fluid shear stress. The steady flow in different kinds of PPFC has been extensively investigated, whereas, the pulsatile flow in the PPFC has received little attention. In consideration of the characteristics of geometrical size and pulsatile flow in the PPFC, the 3-D pulsatile flow was decomposed into a 2-D pulsatile flow in the vertical plane, and an incompressible plane potential flow in the horizontal plane. A simple method was then proposed to analyze the pulsatile flow in the PPFC with spatial shear stress gradient. On the basis of the method, the pulsatile fluid shear stresses in several reported PPFCs with spatial shear stress gradients were calculated. The results were theoretically meaningful for applying the PPFCs in-vitro, to simulate the pulsatile fluid shear stress environment, to which cultured ECs were exposed.
文摘This paper compares the fluid flow phenomena occurring within a fractured reservoir for three different fracture models using computational fluid dynamics.The effect of the fracture-matrix interface condition is studied on the pressure and velocity distribution.The fracture models were compared based on the variation in pressure and permeability conditions.The model was developed for isotropic and anisotropic permeability conditions.The results suggest that the fracture aperture can have a drastic effect on fluid flow.The porous fracture-matrix interface condition produces more realistic transport of fluids.By increasing the permeability in the isotropic porous matrix,the pressure drop was significantly higher in both the fracture and reservoir region.Under anisotropic conditions in the 3D fractured reservoir,the effect of the higher longitudinal permeability was found to lower the pressure in the fractured reservoir.Depending on the properties of the fractured reservoir,this study can enhance the understanding of fracture-matrix fluid interaction and provide a method for production optimisation.
基金BJB thanks the Canada Chairs program for a Research Chair in MRI of Materials[950e230894]an NSERC Discovery Grant[2015-6122]GRG thanks NSERC for a Discovery Grant[RGPIN-2017-06095].
文摘An exploratory multinuclear magnetic resonance(MR)and magnetic resonance imaging(MRI)study was performed on lithium-ion battery cells with ^(7)Li,^(19)F,and ^(1)H measurements.A variable field superconducting magnet with a fixed frequency parallel-plate radiofrequency(RF)probe was employed in the study.The magnetic field was changed to set the resonance frequency of each nucleus to the fixed RF probe frequency of 33.7 MHz.Two cartridge-like lithium-ion cells,with graphite anodes and LiNi_(0.5)Mn_(0.3)Co_(0.2)O_(2)(NMC)cathodes,were interrogated.One cell was pristine,and one was charged to a cell voltage of 4.2 V.The results presented demonstrate the great potential of the variable field magnet approach in multinuclear measurement of lithium-ion batteries.These methods open the door for developing faster and simpler methods for detecting,quantifying,and interpreting MR and MRI data from lithium-ion and other batteries.
文摘The transient feeding to parallel-plate transmission lines from coaxial line is optimized by using the Finite-Difference Time-Domain (FDTD) method and a simple FDTD feed model. Observing the reflected voltages, this letter presents the optimal feeding position and ratio of width to height for a given input impedance of the coaxial line.
基金supported by a grant from the Science and Technology Division,Zhejiang Provincial Government,under the Key Project of the International Collaborative Program(Grant No.2006C14021)Additional support is from the K.C. Wong Magna Fund of Ningbo University.
文摘Quartz crystal resonators are typical piezoelectric acoustic wave devices for frequency control applications with mechanical vibration frequency at the radio-frequency （RF） range. Precise analyses of the vibration and deformation are generally required in the resonator design and improvement process. The considerations include the presence of electrodes, mountings, bias fields such as temperature, initial stresses, and acceleration. Naturally, the finite element method is the only effective tool for such a coupled problem with multi-physics nature. The main challenge is the extremely large size of resulted linear equations. For this reason, we have been employing the Mindlin plate equations to reduce the computational difficulty. In addition, we have to utilize the parallel computing techniques on Linux clusters, which are widely available for academic and industrial applications nowadays, to improve the computing efficiency. The general principle of our research is to use open source software components and public domain technology to reduce cost for developers and users on a Linux cluster. We start with a mesh generator specifically for quartz crystal resonators of rectangular and circular types, and the Mindlin plate equations are implemented for the finite element analysis. Computing techniques like parallel processing, sparse matrix handling, and the latest eigenvalue extraction package are integrated into the program. It is clear from our computation that the combination of these algorithms and methods on a cluster can meet the memory requirement and reduce computing time significantly.
基金the Canada Chairs program for a Research Chair in MRI of Materials[950-230894]an NSERC Discovery Grant[2015-6122].GRG thanks NSERC for a Discovery Grant[RGPIN-2017-06095].
文摘We explore the use of the parallel-plate resonator for the study of thin cuboid samples over a wide range of magnetic resonance frequencies.The parallel-plate resonator functions at frequencies from tens to hundreds of MHz.Seven parallel-plate resonators are presented and discussed in a frequency range from 8 to 500 MHz.Magnetic resonance experiments were performed on both horizontal and vertical bore magnet systems with lithium and hydrogen nuclei.Parallel-plate radiofrequency(RF)probes are easy to build and easy to optimize.Experiments and simulations showed good sensitivity of the parallel-plate RF probe geometry with a small decrease in sensitivity at higher frequencies.
基金supported by National Natural Science Foundation of China(Nos.51366012 and 11105067)Jiangxi Province Young Scientists(Jinggang Star)Cultivation Plan of China(No.20133BCB23008)+1 种基金Natural Science Foundation of Jiangxi,China(No.20151BAB206047)Jiangxi Province Higher School Science and Technology Landing Plan of China(No.KJLD-14015)
文摘A comprehensive dynamic model consisting of 66 reactions and 24 species is developed to investigate the dynamic characteristics of ozone generation by positive pulsed dielectric barrier discharge（DBD） using parallel-plate reactor in air.The electron energy conservation equation is coupled to the electron continuity equation,the heavy species continuity equation,and Poisson＇s equation for a better description.The reliability of the model is experimentally confirmed.The model can be used to predict the temporal and spatial evolution of species,as well as streamer propagation.The simulation results show that electron density increases nearly exponentially in the direction to the anode at the electron avalanche.Streamer propagation velocity is about 5.26×104m/s from anode to cathode in the simulated condition.The primary positive ion,negative ion,and excited species are O_2~＋,O_3^-and O_2（1？g） in pulsed DBD in air,respectively.N_2 O has the largest density among nitrogen oxides.e and N_2~＋densities in the streamer head increase gradually to maximum values with the development of the streamer.Meanwhile,the O_2~＋,O,O_3,N_2（A^3Σ） and N_2 O densities reach maximum values in the vicinity of the anode.
