Shallow water model was employed to approximate the three-dimensional flows of a thin micropump to a two-dimensional thickness-averaged flows. The finite element method and pressure correction algorithm were used to s...Shallow water model was employed to approximate the three-dimensional flows of a thin micropump to a two-dimensional thickness-averaged flows. The finite element method and pressure correction algorithm were used to solve the two- dimensional flows of the pump and calculate the pump flow rate. The numerical results indicate that： 1 ） Phase differences in time of flow velocities and backflows occur across section of diffuser connecting to pump chamber; 2 ） A pair of symmetric vortexes appear inside the pump chamber at the end of suction flow phase; 3 ） The directional flow rate of the pump is dominated by nonlinearity of Navier-Stokes equations. Quantitative relations of the pump flow rate versus the ratio of diffuser length to width, the ratio of diffuser thickness to width, fluid viscosity and backpressure were also given. Possibly maximal flow rate can be achieved by optimizing the pump parameters.展开更多
The limit working parameters and service life of axial piston pump are determined by the carrying ability and lubrication characteristic of its key friction pairs. Therefore, the design and optimization of the key fri...The limit working parameters and service life of axial piston pump are determined by the carrying ability and lubrication characteristic of its key friction pairs. Therefore, the design and optimization of the key friction pairs are always a key and difficult problem in the research on axial piston pump. In the traditional research on piston/cylinder pair, the assembly relationship of piston and cylinder bore is simplified into ideal cylindrical pair, which can not be used to analyze the influences of radial micro-motion of piston on the distribution characteristics of oil-film thickness and pressure in details. In this paper, based on the lubrication theory of the oil film, a numerical simulation model is built, taking the influences of roughness, elastic deformation of piston and pressure-viscosity effect into consideration. With the simulation model, the dynamic characteristics of the radial micro-motion and pressure distribution are analyzed, and the relationships between radial micro-motion and carrying ability, lubrication condition, and abrasion are discussed. Furthermore, a model pump for pressure distribution measurement of oil film between piston and cylinder bore is designed. The comparison of simulation and experimental results of pressure distribution shows that the simulation model has high accuracy. The experiment and simulation results demonstrate that the pressure distribution has peak values that are much higher than the boundary pressure in the piston chamber due to the radial micro-motion, and the abrasion of piston takes place mainly on the hand close to piston ball. In addition, improvement of manufacturing roundness and straightness of piston and cylinder bore is helpful to improve the carrying ability of piston/cylinder pair. The proposed research provides references for designing piston/cylinder pair, and helps to prolong the service life of axial piston pump.展开更多
The structure and operating principle of micro valveless pump were investigated theoretically and experimentally. The mathematical model of pressure and flow rate within the micro nozzle/diffuser was established to an...The structure and operating principle of micro valveless pump were investigated theoretically and experimentally. The mathematical model of pressure and flow rate within the micro nozzle/diffuser was established to analyze the effects of nozzle/diffuser parameters on the output flow rate of the micro valveless pump.The experiments were carried out with different structural parameters, driving frequencies, vibration amplitudes and stiffness of the driving diaphragms. Effects of the structural parameters and driving conditions on the operation performance of the pump are discussed in detail. The work provides useful reference for structure optimization selection of the driving diaphragm of micro valveless pump.展开更多
Due to the rise of biological and MEMS technology in recent years, some micro flow system components have drawn attention and been developed by many investigators. The importance of micro-pumps manufactured is higher ...Due to the rise of biological and MEMS technology in recent years, some micro flow system components have drawn attention and been developed by many investigators. The importance of micro-pumps manufactured is higher than the other part of micro flow system since it is the power source of the entire micro-flow system and responsible for driving working fluid in the microfluidic system. In actual operation, the instability and bad dynamic characteristics of the micro-pump will cause larger fluid flow mobility error, such as transport behavior and response procedures failure, etc., and even damage the microfluidic system. Therefore, to investigate the stability and dynamic characteristics of a micro pump is necessary. The Finite element analysis (FEA), ANSYS Workbench, is employed to analyze the dynamic characteristics of this micro pump, and experiment is also considered in this study.展开更多
This paper studies the Stokes flow of micro-polar fluids by peristaltic pumping through the cylindrical tube under the effect of the slip boundary condition. The motion of the wall is governed by the sinusoidal wave e...This paper studies the Stokes flow of micro-polar fluids by peristaltic pumping through the cylindrical tube under the effect of the slip boundary condition. The motion of the wall is governed by the sinusoidal wave equation. The analytical and numerical solutions for the axial velocity, the micro-polar vector, the stream function, the pressure gradient, the friction force, and the mechanical efficiency are obtained by using the lu- brication theory under the low Reynolds number and long wavelength approximations. The impacts of the emerging parameters, such as the coupling number, the micro-polar parameter, the slip parameter on pumping characteristics, the friction force, the velocity profile, the mechanical efficiency, and the trapping phenomenon are depicted graphically. The numerical results infer that large pressure is required for peristaltic pumping when the coupling number is large, while opposite behaviors are found for the micro-polar parameter and the slip parameter. The size of the trapped bolus reduces with the increase in the coupling number and the micro-polar parameter, whereas it blows up with the increase in the slip parameter.展开更多
目的探讨丙泊酚微量泵输注联合前锯肌平面阻滞对老年胃癌根治术患者麻醉药物用量、术后谵妄及躁动影响。方法前瞻性选取2021年1月至2023年12月临汾市人民医院收治的80例老年胃癌患者作为研究对象,按照抽签法分为观察组与对照组,每组各4...目的探讨丙泊酚微量泵输注联合前锯肌平面阻滞对老年胃癌根治术患者麻醉药物用量、术后谵妄及躁动影响。方法前瞻性选取2021年1月至2023年12月临汾市人民医院收治的80例老年胃癌患者作为研究对象,按照抽签法分为观察组与对照组,每组各40例。所有患者均择期实施胃癌根治术治疗,对照组患者实施单纯全身静脉麻醉,术中采取丙泊酚微量泵注维持麻醉,观察组在对照组基础上增加前锯肌平面阻滞。对比两组麻醉效果,麻醉前(T1)、麻醉后2 min(T2)、手术开始即刻(T3)及手术结束即刻(T4)平均动脉压、血氧饱和度及心率水平变化,对比两组麻醉药物总用量,术后1、6及12 h疼痛及镇静情况,最后对比其谵妄及躁动发生率。结果观察组麻醉效果Ⅰ级患者比率为65.00%,高于对照组(37.50%),观察组麻醉效果Ⅲ级患者比率为2.50%,低于对照组(15.00%),差异均有统计学意义(P<0.05)。观察组T2、T3、T4时MAP水平分别为(80.94±6.26)、(83.37±6.52)、(92.39±5.18)mmHg,均高于对照组[(74.33±4.85)、(76.21±4.42)、(83.72±11.22)mmHg],观察组T2、T3时血氧饱和度分别为(98.84±1.67)%、(98.95±1.56)%,均高于对照组[(93.52±2.52)%、(93.12±1.53)%],观察组T2时心率为(80.36±9.27)次/min,低于对照组[(86.28±7.22)次/min],差异均有统计学意义(P<0.05)。两组患者瑞芬太尼用量比较,差异无统计学意义(P>0.05),观察组患者舒芬太尼、丙泊酚用量分别为(43.32±5.12)μg、(251.63±42.52)mg,均明显低于对照组[(46.02±7.25)μg、(281.68±56.12)mg],差异均有统计学意义(P<0.05)。观察组术后1、6、12 h Ramsay评分(1.62±0.28)、(1.08±0.15)、(0.73±0.16)级,均低于对照组[(2.81±0.31)、(1.52±0.12)、(1.03±0.12)级];观察组术后1、6、12 h VAS评分(3.41±1.23)、(2.44±0.21)、(2.17±0.31)分,均低于对照组[(4.39±1.38)、(3.57±0.11)、(3.03±0.25)分],差异均有统计学意义(P<0.05)。观察组术后谵妄及躁动发生率分别为5.00%、2.50%,均明显低于对照组(22.50%、17.50%),差异均有统计学意义(P<0.05)。结论丙泊酚微量泵输注联合前锯肌平面阻滞可提升老年胃癌根治术患者麻醉效果,稳定术中生命体征,减少麻醉药物用量,同时可提升术后镇痛及镇静效果,降低躁动及谵妄发生率。展开更多
文摘Shallow water model was employed to approximate the three-dimensional flows of a thin micropump to a two-dimensional thickness-averaged flows. The finite element method and pressure correction algorithm were used to solve the two- dimensional flows of the pump and calculate the pump flow rate. The numerical results indicate that： 1 ） Phase differences in time of flow velocities and backflows occur across section of diffuser connecting to pump chamber; 2 ） A pair of symmetric vortexes appear inside the pump chamber at the end of suction flow phase; 3 ） The directional flow rate of the pump is dominated by nonlinearity of Navier-Stokes equations. Quantitative relations of the pump flow rate versus the ratio of diffuser length to width, the ratio of diffuser thickness to width, fluid viscosity and backpressure were also given. Possibly maximal flow rate can be achieved by optimizing the pump parameters.
基金supported by National Natural Science Foundation of China(Grant No. 51075360)Doctoral Foundation of Ministry of Education of China(Grant No. 20090101110041)National Key Technology R&D Program of the Twelfth Five-year Plan of China(Grant No. 2011BAF09B03)
文摘The limit working parameters and service life of axial piston pump are determined by the carrying ability and lubrication characteristic of its key friction pairs. Therefore, the design and optimization of the key friction pairs are always a key and difficult problem in the research on axial piston pump. In the traditional research on piston/cylinder pair, the assembly relationship of piston and cylinder bore is simplified into ideal cylindrical pair, which can not be used to analyze the influences of radial micro-motion of piston on the distribution characteristics of oil-film thickness and pressure in details. In this paper, based on the lubrication theory of the oil film, a numerical simulation model is built, taking the influences of roughness, elastic deformation of piston and pressure-viscosity effect into consideration. With the simulation model, the dynamic characteristics of the radial micro-motion and pressure distribution are analyzed, and the relationships between radial micro-motion and carrying ability, lubrication condition, and abrasion are discussed. Furthermore, a model pump for pressure distribution measurement of oil film between piston and cylinder bore is designed. The comparison of simulation and experimental results of pressure distribution shows that the simulation model has high accuracy. The experiment and simulation results demonstrate that the pressure distribution has peak values that are much higher than the boundary pressure in the piston chamber due to the radial micro-motion, and the abrasion of piston takes place mainly on the hand close to piston ball. In addition, improvement of manufacturing roundness and straightness of piston and cylinder bore is helpful to improve the carrying ability of piston/cylinder pair. The proposed research provides references for designing piston/cylinder pair, and helps to prolong the service life of axial piston pump.
文摘The structure and operating principle of micro valveless pump were investigated theoretically and experimentally. The mathematical model of pressure and flow rate within the micro nozzle/diffuser was established to analyze the effects of nozzle/diffuser parameters on the output flow rate of the micro valveless pump.The experiments were carried out with different structural parameters, driving frequencies, vibration amplitudes and stiffness of the driving diaphragms. Effects of the structural parameters and driving conditions on the operation performance of the pump are discussed in detail. The work provides useful reference for structure optimization selection of the driving diaphragm of micro valveless pump.
文摘Due to the rise of biological and MEMS technology in recent years, some micro flow system components have drawn attention and been developed by many investigators. The importance of micro-pumps manufactured is higher than the other part of micro flow system since it is the power source of the entire micro-flow system and responsible for driving working fluid in the microfluidic system. In actual operation, the instability and bad dynamic characteristics of the micro-pump will cause larger fluid flow mobility error, such as transport behavior and response procedures failure, etc., and even damage the microfluidic system. Therefore, to investigate the stability and dynamic characteristics of a micro pump is necessary. The Finite element analysis (FEA), ANSYS Workbench, is employed to analyze the dynamic characteristics of this micro pump, and experiment is also considered in this study.
文摘This paper studies the Stokes flow of micro-polar fluids by peristaltic pumping through the cylindrical tube under the effect of the slip boundary condition. The motion of the wall is governed by the sinusoidal wave equation. The analytical and numerical solutions for the axial velocity, the micro-polar vector, the stream function, the pressure gradient, the friction force, and the mechanical efficiency are obtained by using the lu- brication theory under the low Reynolds number and long wavelength approximations. The impacts of the emerging parameters, such as the coupling number, the micro-polar parameter, the slip parameter on pumping characteristics, the friction force, the velocity profile, the mechanical efficiency, and the trapping phenomenon are depicted graphically. The numerical results infer that large pressure is required for peristaltic pumping when the coupling number is large, while opposite behaviors are found for the micro-polar parameter and the slip parameter. The size of the trapped bolus reduces with the increase in the coupling number and the micro-polar parameter, whereas it blows up with the increase in the slip parameter.
文摘目的探讨丙泊酚微量泵输注联合前锯肌平面阻滞对老年胃癌根治术患者麻醉药物用量、术后谵妄及躁动影响。方法前瞻性选取2021年1月至2023年12月临汾市人民医院收治的80例老年胃癌患者作为研究对象,按照抽签法分为观察组与对照组,每组各40例。所有患者均择期实施胃癌根治术治疗,对照组患者实施单纯全身静脉麻醉,术中采取丙泊酚微量泵注维持麻醉,观察组在对照组基础上增加前锯肌平面阻滞。对比两组麻醉效果,麻醉前(T1)、麻醉后2 min(T2)、手术开始即刻(T3)及手术结束即刻(T4)平均动脉压、血氧饱和度及心率水平变化,对比两组麻醉药物总用量,术后1、6及12 h疼痛及镇静情况,最后对比其谵妄及躁动发生率。结果观察组麻醉效果Ⅰ级患者比率为65.00%,高于对照组(37.50%),观察组麻醉效果Ⅲ级患者比率为2.50%,低于对照组(15.00%),差异均有统计学意义(P<0.05)。观察组T2、T3、T4时MAP水平分别为(80.94±6.26)、(83.37±6.52)、(92.39±5.18)mmHg,均高于对照组[(74.33±4.85)、(76.21±4.42)、(83.72±11.22)mmHg],观察组T2、T3时血氧饱和度分别为(98.84±1.67)%、(98.95±1.56)%,均高于对照组[(93.52±2.52)%、(93.12±1.53)%],观察组T2时心率为(80.36±9.27)次/min,低于对照组[(86.28±7.22)次/min],差异均有统计学意义(P<0.05)。两组患者瑞芬太尼用量比较,差异无统计学意义(P>0.05),观察组患者舒芬太尼、丙泊酚用量分别为(43.32±5.12)μg、(251.63±42.52)mg,均明显低于对照组[(46.02±7.25)μg、(281.68±56.12)mg],差异均有统计学意义(P<0.05)。观察组术后1、6、12 h Ramsay评分(1.62±0.28)、(1.08±0.15)、(0.73±0.16)级,均低于对照组[(2.81±0.31)、(1.52±0.12)、(1.03±0.12)级];观察组术后1、6、12 h VAS评分(3.41±1.23)、(2.44±0.21)、(2.17±0.31)分,均低于对照组[(4.39±1.38)、(3.57±0.11)、(3.03±0.25)分],差异均有统计学意义(P<0.05)。观察组术后谵妄及躁动发生率分别为5.00%、2.50%,均明显低于对照组(22.50%、17.50%),差异均有统计学意义(P<0.05)。结论丙泊酚微量泵输注联合前锯肌平面阻滞可提升老年胃癌根治术患者麻醉效果,稳定术中生命体征,减少麻醉药物用量,同时可提升术后镇痛及镇静效果,降低躁动及谵妄发生率。
