According to characteristic of hydroforming of parallel multi-branch tubes,multi-objective problems were transformed to single objective problem of relational grade comparison by grey system theory.Two different objec...According to characteristic of hydroforming of parallel multi-branch tubes,multi-objective problems were transformed to single objective problem of relational grade comparison by grey system theory.Two different objectives were selected,according to the principle that process parameters were optimal which of grey relational grade were maximum,the optimal loading parameters under different objective condition were obtained,and loading paths were optimized.The results indicated that parallel multi-branch tubes hydroformed under loading paths optimized by grey system theory could meet with the requirement that objective was optimal.And the optimal loading paths under different objectives were different,and the appropriate objective should be selected according to forming characteristic.展开更多
Microchannel heat sink with high heat transfer coefficients has been extensively investigated due to its wide application prospective in electronic cooling. However, this cooling system requires a separate pump to dri...Microchannel heat sink with high heat transfer coefficients has been extensively investigated due to its wide application prospective in electronic cooling. However, this cooling system requires a separate pump to drive the fluid transfer, which is uneasy to minimize and reduces their reliability and applicability of the whole system. In order to avoid these problems, valveless piezoelectric pump with fractal-like Y-shape branching tubes is proposed. Fractal-like Y-shape branching tube used in microchannel heat sinks is exploited as no-moving-part valve of the valveless piezoelectric pump. In order to obtain flow characteristics of the pump, the relationship between tube structure and flow rate of the pump is studied. Specifically, the flow resistances of fractal-like Y-shape branching tubes and flow rate of the pump are analyzed by using fractal theory. Then, finite element software is employed to simulate the flow field of the tube, and the relationships between pressure drop and flow rate along merging and dividing flows are obtained. Finally, valveless piezoelectric pumps with fractal-like Y-shape branching tubes with different fractal dimensions of diameter distribution are fabricated, and flow rate experiment is conducted. The experimental results show that the flow rate of the pump increases with the rise of fractal dimension of the tube diameter. When fractal dimension is 3, the maximum flow rate of the valveless pump is 29.16 mL/min under 100 V peak to peak （13 Hz） power supply, which reveals the relationship between flow rate and fractal dimensions of tube diameter distribution. This paper investigates the flow characteristics of valveless piezoelectric pump with fractal-like Y-shape branching tubes, which provides certain references for valveless piezoelectric pump with fractal-like Y-shape branching tubes in application on electronic chip cooling.展开更多
Microfluidic behavior of ternary mixed carrier solvents of water-acetonitrile-ethyl acetate (2:3:1 volume ratio) was examined by use of a microchip incorporating microchannels in which one wide channel was separated i...Microfluidic behavior of ternary mixed carrier solvents of water-acetonitrile-ethyl acetate (2:3:1 volume ratio) was examined by use of a microchip incorporating microchannels in which one wide channel was separated into three narrow channels, i.e., triple-branched microchannels. When the ternary carrier solution containing the fluorescent dyes, hydrophobic perylene (blue) and relatively hydrophilic Eosin Y (green), was fed into the wide channel under laminar flow conditions, the carrier solvent molecules or fluorescence dyes were radially distributed in the channel, forming inner (organic solvent-rich major;blue) and outer (water-rich minor;green) phases in the wide channel. And then, in the narrow channels, perylene molecules mostly appeared to flow through the center narrow channel and Eosin Y, which is distributed in the outer phases in the wide channel, flowed through the both side narrow channels. A metal ion, Cu(II) as a model, dissolved in the ternary mixed carrier solution was also examined. The Cu(II) showed fluidic behavior, transferring from the homogeneous carrier solution to the water-rich solution in the side narrow channels through the triple-branched microchannels.展开更多
This paper proposed a T- Y tube model to simulate foe input impedance of arterial system. It improves and extends the asymmetric T-tube model which was firstproposed by O' Rourke[1] and developed laier by Liu et a...This paper proposed a T- Y tube model to simulate foe input impedance of arterial system. It improves and extends the asymmetric T-tube model which was firstproposed by O' Rourke[1] and developed laier by Liu et al.[2]. Based on foe asymmetricT-tube model. a T-Y tube model was proposed by adding branching tubes whichrepresem the iliac arteries.All the tubes are considered to be uniform,viscoelasticlongitudinally tethered cylindrical tubes.The upper tube terminates with a windkesselmodel, while the terminal arterioles of the lowr tube are expressed as a resistance.After proper eraluation of the parameters.the impedance of the arterial system iscalculated under normal physiological and hypertensive condition.The model canpredict impedance in good agreement with the experimentally obtained data no matterin normal physiological condition or in pathological condition In comparison with theasymmeric T-tube model,T- Y tube model is closer to anatomy structure of the human arlerial system and at the sametime much simpler than the extremely complex multiplebranching tube model Therefore it will be a valuable model in studying the influencesof various parameters on aorta impedance and ventricular-vascular coupling.展开更多
旁支管是应用广泛的共振消声结构。应用解析方法推导旁支管共振结构的传递损失和共振频率计算公式,考虑三维修正,给出旁支管共振消声带宽与各种参数的定量关系,定义消声带宽与共振频率的比值为带宽参数,研究带宽参数与传递损失以及旁支...旁支管是应用广泛的共振消声结构。应用解析方法推导旁支管共振结构的传递损失和共振频率计算公式,考虑三维修正,给出旁支管共振消声带宽与各种参数的定量关系,定义消声带宽与共振频率的比值为带宽参数,研究带宽参数与传递损失以及旁支管其他参数的变化关系,最终给出旁支管共振消声带宽计算公式。最后,通过三维有限元方法(Finite Element Method,FEM)计算旁支管的消声带宽并与文中公式结果进行比较,结果显示,两种结果吻合良好,验证了计算公式的可靠性和准确性。展开更多
针对缝洞型碳酸盐岩储层酸压改造投入高、效果不理想的问题,基于羽状分支管增产原理,设计了羽状分支管增产管柱和羽状分支管增产关键工具——分支管短节。分支管应力分布和屈曲特性的有限元法分析结果发现,ϕ8.0和ϕ10.0 mm 316L型不锈钢...针对缝洞型碳酸盐岩储层酸压改造投入高、效果不理想的问题,基于羽状分支管增产原理,设计了羽状分支管增产管柱和羽状分支管增产关键工具——分支管短节。分支管应力分布和屈曲特性的有限元法分析结果发现,ϕ8.0和ϕ10.0 mm 316L型不锈钢分支管的最大应力小于材料的屈服强度,属于弹性变形范畴,满足使用要求。地面试验结果表明,分支管可以从分支管短节中伸出,启动压力3.0 MPa,最高压力3.5 MPa。性能测试结果发现,分支管启动前经喷嘴高速喷出的酸液可以在岩心上造孔,分支管伸出短节后可以进入岩心并在岩心中穿行。羽状分支管增产技术在塔河油田碳酸盐岩储层改造应用的可行性分析表明,目标区块碳酸盐岩岩样的溶解率达100%,喷酸造孔速率达2.6~14.4 m/h,具备实施该技术的条件。研究结果表明,羽状分支管增产技术具有施工压力低的优点,在塔河油田碳酸盐岩储层改造中应用具有很强的可行性,前景良好。展开更多
基金Sponsored by the National Natural Science Foundation of China(Grant No.U0934006)
文摘According to characteristic of hydroforming of parallel multi-branch tubes,multi-objective problems were transformed to single objective problem of relational grade comparison by grey system theory.Two different objectives were selected,according to the principle that process parameters were optimal which of grey relational grade were maximum,the optimal loading parameters under different objective condition were obtained,and loading paths were optimized.The results indicated that parallel multi-branch tubes hydroformed under loading paths optimized by grey system theory could meet with the requirement that objective was optimal.And the optimal loading paths under different objectives were different,and the appropriate objective should be selected according to forming characteristic.
基金Supported by National Natural Science Foundation of China(Grant Nos.51275235,51375227)Major Research Plan of National Natural Science Foundation of China(Grant No.91223201)Independent Projects Fund of State Key Lab of Mechanics and Control of Mechanical Structures of China(Grant No.0313G01)
文摘Microchannel heat sink with high heat transfer coefficients has been extensively investigated due to its wide application prospective in electronic cooling. However, this cooling system requires a separate pump to drive the fluid transfer, which is uneasy to minimize and reduces their reliability and applicability of the whole system. In order to avoid these problems, valveless piezoelectric pump with fractal-like Y-shape branching tubes is proposed. Fractal-like Y-shape branching tube used in microchannel heat sinks is exploited as no-moving-part valve of the valveless piezoelectric pump. In order to obtain flow characteristics of the pump, the relationship between tube structure and flow rate of the pump is studied. Specifically, the flow resistances of fractal-like Y-shape branching tubes and flow rate of the pump are analyzed by using fractal theory. Then, finite element software is employed to simulate the flow field of the tube, and the relationships between pressure drop and flow rate along merging and dividing flows are obtained. Finally, valveless piezoelectric pumps with fractal-like Y-shape branching tubes with different fractal dimensions of diameter distribution are fabricated, and flow rate experiment is conducted. The experimental results show that the flow rate of the pump increases with the rise of fractal dimension of the tube diameter. When fractal dimension is 3, the maximum flow rate of the valveless pump is 29.16 mL/min under 100 V peak to peak （13 Hz） power supply, which reveals the relationship between flow rate and fractal dimensions of tube diameter distribution. This paper investigates the flow characteristics of valveless piezoelectric pump with fractal-like Y-shape branching tubes, which provides certain references for valveless piezoelectric pump with fractal-like Y-shape branching tubes in application on electronic chip cooling.
文摘Microfluidic behavior of ternary mixed carrier solvents of water-acetonitrile-ethyl acetate (2:3:1 volume ratio) was examined by use of a microchip incorporating microchannels in which one wide channel was separated into three narrow channels, i.e., triple-branched microchannels. When the ternary carrier solution containing the fluorescent dyes, hydrophobic perylene (blue) and relatively hydrophilic Eosin Y (green), was fed into the wide channel under laminar flow conditions, the carrier solvent molecules or fluorescence dyes were radially distributed in the channel, forming inner (organic solvent-rich major;blue) and outer (water-rich minor;green) phases in the wide channel. And then, in the narrow channels, perylene molecules mostly appeared to flow through the center narrow channel and Eosin Y, which is distributed in the outer phases in the wide channel, flowed through the both side narrow channels. A metal ion, Cu(II) as a model, dissolved in the ternary mixed carrier solution was also examined. The Cu(II) showed fluidic behavior, transferring from the homogeneous carrier solution to the water-rich solution in the side narrow channels through the triple-branched microchannels.
文摘This paper proposed a T- Y tube model to simulate foe input impedance of arterial system. It improves and extends the asymmetric T-tube model which was firstproposed by O' Rourke[1] and developed laier by Liu et al.[2]. Based on foe asymmetricT-tube model. a T-Y tube model was proposed by adding branching tubes whichrepresem the iliac arteries.All the tubes are considered to be uniform,viscoelasticlongitudinally tethered cylindrical tubes.The upper tube terminates with a windkesselmodel, while the terminal arterioles of the lowr tube are expressed as a resistance.After proper eraluation of the parameters.the impedance of the arterial system iscalculated under normal physiological and hypertensive condition.The model canpredict impedance in good agreement with the experimentally obtained data no matterin normal physiological condition or in pathological condition In comparison with theasymmeric T-tube model,T- Y tube model is closer to anatomy structure of the human arlerial system and at the sametime much simpler than the extremely complex multiplebranching tube model Therefore it will be a valuable model in studying the influencesof various parameters on aorta impedance and ventricular-vascular coupling.
文摘旁支管是应用广泛的共振消声结构。应用解析方法推导旁支管共振结构的传递损失和共振频率计算公式,考虑三维修正,给出旁支管共振消声带宽与各种参数的定量关系,定义消声带宽与共振频率的比值为带宽参数,研究带宽参数与传递损失以及旁支管其他参数的变化关系,最终给出旁支管共振消声带宽计算公式。最后,通过三维有限元方法(Finite Element Method,FEM)计算旁支管的消声带宽并与文中公式结果进行比较,结果显示,两种结果吻合良好,验证了计算公式的可靠性和准确性。
