Investigation on the Radial Micro-motion about Piston of Axial Piston Pump

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.

Modeling and simulation of a high-frequency micro-pump based on giant magnetostrictive material (GMM)

A new type of high-frequency micro-pump was designed, in which GMA (Giant Magnetostrictive Actuator) was employed to replace the traditional motor drive, owing to its significant characteristics of fast response, high accuracy, easily miniaturized and so on. Both the mathematic and simulation models of the micro-pump were built.A set of raw data was used for simulation studies.The results show that the micro-pump based on GMA has achieved the features of high-frequency response and high accuracy, theoretically displaying the performance merits of a giant magnetostrictive material (GMM) high-frequency micro-pump.

Stokes flow of micro-polar fluids by peristaltic pumping through tube with slip boundary condition

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.

5-羟色胺转运蛋白显像剂^(11)C-DASB的自动化合成及Micro PET/CT显像

目的:自动化合成5-羟色胺转运蛋白显像剂11 C-DASB并进行大鼠Micro PET/CT显像;方法:通过改变甲基化试剂、溶解前体溶剂及反应条件,得到优化的标记条件作为碳-11多功能合成模块的输入参数,进行自动化合成11 C-DASB,大鼠静脉注射11 C-DASB 45 min后进行显像;结果:采用11 C-CH3-Triflate作为甲基化试剂,通入新配制的含1mg去甲基DASB前体的500μL DMSO溶液内,80℃下加热2min,标准率为63.7%,大鼠显像表明,11 C-DASB特异性的浓聚于SERT富集区域;结论:经优化,11 C-DASB自动化合成可得到较高产率,大鼠显像表明,其特异性浓聚于SERT富集区域,有望作为5-羟色胺转运蛋白显像剂。

^(18)F-氟赤硝基咪唑micro PET/CT评价裸鼠乳腺癌早期放疗疗效实验研究

目的探讨^(18)F-氟赤硝基咪唑micro PET/CT评价裸鼠MDA-MB231乳腺癌早期放疗疗效的价值。方法建立16只裸鼠MDA-MB231乳腺癌模型,将其按照随机对照原则分为两组:对照组(A组)、放疗组(B组),每组8只。每组裸鼠行micro PET/CT显像,测定每只裸鼠肿瘤SUVmax值。完成显像后,常规HE染色观察每组肿瘤组织形态学特征,免疫组化方法测定每组肿瘤细胞乏氧诱导因子-1α(HIF-1α)的表达情况。结果放疗前,对照组与放疗组SUVmax值差异无统计学意义(t=0. 375,P> 0. 05)。放疗组放疗后48 h裸鼠肿瘤组织SUVmax值较放疗前(t=9. 958,P <0. 05)、放疗后24 h(t=16. 506,P <0. 05)明显降低,差异有统计学意义(F=58. 860,P <0. 05)。放疗后24 h SUVmax值也低于放疗前24 h(t=5. 405,P <0. 05),差异有统计学意义。HE染色结果显示放疗组肿瘤细胞坏死较对照组更加明显。免疫组化结果显示放疗组放疗后HIF-1α表达阳性率明显低于放疗前(t=14. 802,P <0. 05),差异具有统计学意义。相关性分析结果显示肿瘤SUVmax与HIF-1α的表达呈明显正相关性(r=0. 865,P <0. 05)。结论^(18)F-氟赤硝基咪唑micro PET/CT可以监测肿瘤内部的乏氧状态,并且可以评价裸鼠MDA-MB231乳腺癌的早期放疗疗效。

NUMERICAL STUDY OF PERIODICAL FLOWS OF PIEZOELECTRIC VALVELESS MICROPUMP FOR BIOCHIPS

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.

Using Finite Element Analysis and Experimental Analysis on Vibration of a Piezoelectric Micro Pump

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.

Effects of structural parameters and rigidity of driving diaphragm on flow characteristics of micro valveless pump

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.

Principle of a Multistage Electroosmotic Pump and Its Application in Microfluidic Chip

In the past decade, a variety of microfabricated pumps and fluid-handling systems based on ultrasonic, electricity, light, magnet and heat actuated technologies were reported[1], which could be classified into two groups: membrane-displacement pumps and field-induced flow pumps. An advantage of field-induced flow pumps over the former is that they do not require moving parts, such as check valves which complicate the fabrication, sealing, and operation of the systems.……

Effect of Surface Roughness in Micro-nano Scale on Slotted Waveguide Arrays in Ku-band

Modeling of the roughness in micro-nano scale and its influence have not been fully investigated, however the roughness will cause amplitude and phase errors of the radiating slot, and decrease the precision and efficiency of the SWA in Ku-band. Firstly, the roughness is simulated using the electromechanical coupled（EC） model. The relationship between roughness and the antenna＇s radiation properties is obtained. For verification, an antenna proto- type is manufactured and tested, and the simulation method is introduced. According to the prototype, a contrasting experiment dealing with the flatness of the radiating plane is conducted to test the simulation method. The advantage of the EC model is validated by comparisons of the EC model and two classical roughness models （sine wave and fractal function）, which shows that the EC model gives a more accurate description model for roughness, the maxi- mum error is 13%. The existence of roughness strongly broadens the beamwidth and raises the side-lobe level of SWA, which is 1.2 times greater than the ideal antenna. In addition, effect of the EC model＇s evaluation indices is investigated, the most affected scale of the roughness is found, which is 1/10 of the working wavelength. The proposed research provides the instruction for antenna designing and manufacturing.

Autonomous Multi-Factor Energy Flows Controller (AmEFC): Enhancing Renewable Energy Management with Intelligent Control Systems Integration

The transition to sustainable energy systems is one of the defining challenges of our time, necessitating innovations in how we generate, distribute, and manage electrical power. Micro-grids, as localized energy hubs, have emerged as a promising solution to integrate renewable energy sources, ensure energy security, and improve system resilience. The Autonomous multi-factor Energy Flow Controller (AmEFC) introduced in this paper addresses this need by offering a scalable, adaptable, and resilient framework for energy management within an on-grid micro-grid context. The urgency for such a system is predicated on the increasing volatility and unpredictability in energy landscapes, including fluctuating renewable outputs and changing load demands. To tackle these challenges, the AmEFC prototype incorporates a novel hierarchical control structure that leverages Renewable Energy Sources (RES), such as photovoltaic systems, wind turbines, and hydro pumps, alongside a sophisticated Battery Management System (BMS). Its prime objective is to maintain an uninterrupted power supply to critical loads, efficiently balance energy surplus through hydraulic storage, and ensure robust interaction with the main grid. A comprehensive Simulink model is developed to validate the functionality of the AmEFC, simulating real-world conditions and dynamic interactions among the components. The model assesses the system’s reliability in consistently powering critical loads and its efficacy in managing surplus energy. The inclusion of advanced predictive algorithms enables the AmEFC to anticipate energy production and consumption trends, integrating weather forecasting and inter-controller communication to optimize energy flow within and across micro-grids. This study’s significance lies in its potential to facilitate the seamless incorporation of RES into existing power systems, thus propelling the energy sector towards a more sustainable, autonomous, and resilient future. The results underscore the potential of such a system to revolutionize energy management practices and highlight the importance of smart controller systems in the era of smart grids.

泵用微连通对称双卸荷槽及其困油与流量特性

为了充分提高外啮合齿轮泵的困油性能和完善双卸荷槽的现有设置理论,提出了一种双卸荷槽微连通对称设置的创新结构,并以常规无连通对称设置的双矩形卸荷槽为例,依次给出了创新结构的实现方法,构建了困油压力和理论流量的计算模型,比较分析了常规结构和创新结构下的困油压力、排量损失以及流量脉动质量等。结果表明:啮合点位置越接近最小困油容积位置,创新结构下的卸荷面积越大,突出解决了常规结构下该处的零卸荷面积问题;通过充分缓和常规结构下的困油压力,创新结构有效地避免了困油的高压冲击与低压气穴所造成的危害;相对于常规结构,创新结构的理论排量稍有下降,流量脉动有所加剧等。研究结果可为齿轮泵的优化设计提供参考。

不同流量下泵前微压网式过滤器内部流场的数值模拟

泵前微压网式过滤器作为一种新型的灌溉过滤装置,具有结构简单、适配性高以及能耗低等优点。为了探究泵前微压网式过滤器内部流场的运行状态,采用了物理模型试验、数值计算及理论分析的方法,从微观角度对清水条件下泵前微压网式过滤器在不同流量(5、8、11、14、17 m^(3)/h)的水力性能和水流运动状态进行分析。结果表明:标准k-ε模型可作为模拟泵前微压网式过滤器清水流场的湍流模型;滤网内部流速分布不均匀,随流量呈现不同形态的“火烛”形态,出水口对过滤器内部影响范围随流量增加而增大;过滤器内部同时出现高压区和负压区,滤网底部为水头损失主要发生位置。研究成果可为泵前过滤设备的浑水数值模拟和结构优化提供理论和技术支撑。

可变形磨损模型下微型离心泵复合磨损研究

为了探究微型离心泵在不同颗粒体积分数下的复合磨损类型与磨损变化,基于计算流体动力学与离散元耦合的方法,通过可变形磨料磨损Archard模型与可变形冲蚀磨损Oka模型对离心泵在不同颗粒体积分数(2%、4%、6%、8%、10%、12%)下的颗粒-部件碰撞占比率、磨损分布与演化进行了研究。通过对比实验发现颗粒体积分数在4%附近时颗粒与叶轮叶片、蜗壳碰撞占比率呈现不同的变化趋势。离心泵磨损以磨料磨损为主,磨料磨损中蜗壳为磨损最严重的部件,占总磨料磨损量的68.5%,随着颗粒体积分数的增加,蜗壳处磨料磨损由断面Ⅷ向断面Ⅰ演化,蜗壳前后端先后磨损。冲蚀磨损高磨损区域主要集中于叶轮叶片,占冲蚀磨损总量的95.83%,蜗壳处冲蚀磨损断面演化规律与磨料磨损变化规律近似,但蜗壳后端最先被磨损。颗粒体积分数对蜗壳磨料磨损变形量影响较大,蜗壳、叶轮磨料磨损变形量与冲蚀磨损变形量具有相似的变化趋势。

微泵静推地尔硫卓在降低高血压急症血浆NT-proBNP中的作用

目的探讨微泵静脉推注地尔硫卓在降低高血压急症患者血浆N末端B型利钠肽原(NT-proBNP)中的作用。方法选取我院62例高血压急症患者,随机分为对照组和观察组。观察组给予地尔硫卓微泵静推,对照组给予乌拉地尔微泵静推,比较不同时间点两组临床疗效、NT-proBNP水平(2 h、8 h)、心率、血压、肝肾功能(5 min、30 min、1 h、3 h)指标变化情况。结果观察组总有效率为96.77%,对照组总有效率为87.10%,两组比较无统计学差异(P>0.05);用药2 h后,两组血浆NT-proBNP无明显差异;用药8 h后,观察组血浆NT-proBNP水平明显低于对照组(P<0.05);给药5 min后,观察组SBP、DBP改善情况明显优于对照组(P<0.05),同一时间点观察组心率明显低于对照组(P<0.05);两组用药前后ALT、BUN、AST、Cr均无明显变化(P>0.05)。结论微泵静脉推注地尔硫卓可有效降低高血压急症患者血浆NT-proBNP水平,降压效果显著,且不良反应较少,值得临床推广应用。

针-柱结构敞开式离子源和微型气泵集成系统的放电特性

设计了一种小型针-柱电晕放电结构,实现了敞开式离子源和微型气泵的系统集成。通过数码相机拍摄的针-柱放电图像和示波器记录的特里切尔放电波形,验证了该针-柱结构在没有外界气流、间隙仅2mm的实验条件下实现了稳定的电晕放电。对针-柱结构电晕放电特性进行了研究,讨论了放电电压、镇流电阻、柱直径大小、针-柱间距等参数对针-柱电晕放电的影响,通过伏安特性曲线分析得出在放电电压为-3 800V、镇流电阻为10MΩ、柱直径为4mm、间距为2mm的实验条件下,产生的离子风气体流速最大(采用testo 405-V1风速仪测得最大气体流速为1.15m/s)。该针-柱结构可采用微机电系统(MEMS)工艺加工实现,有望应用于质谱仪、离子迁移谱、高场非对称波形离子迁移谱等便携式分析仪器中,实现敞开式离子源和微型气泵的双重功能。

流量与含沙量对浮筒网式旋转过滤器水力性能与过滤性能的影响

过滤器是保障微灌系统正常运行的核心设备,而水头损失与过滤效率是评价其性能的2个关键指标。为探明泵前过滤器—浮筒网式旋转过滤器的水力性能和过滤性能,采用方差分析、极差分析、主效应多重比较法对比分析了浮筒网式旋转过滤器在滤网孔径为0.150 mm时,5种不同含沙量、5种不同流量下的水头损失与过滤效率,并确定了试验条件下的最优工况。结果表明:对水头损失而言,流量比含沙量影响大;对过滤效率而言,含沙量的影响更大,且水头损失与过滤效率均随含沙量与流量的增大而增大;最优工况为流量930 L/h、含沙量2.0 g/L,此工况下对应的水头损失为0.281 m,过滤效率为84.01%,可以保证在有良好的过滤效率的同时具有较小的水头损失,从而实现节能减排,高效灌溉的目的。

航天器用微泵激光焊接气孔形成机理研究

为研究微泵激光焊接过程中的气孔形成机理,通过试验分析了激光焊接速度、离焦量、保护气体种类和吹气方式对微泵焊缝气孔率的影响规律。结果表明,随着激光离焦量的增加,焊缝气孔率逐渐降低,当激光离焦量小于+3 mm时,激光焊接模式为深熔焊,焊缝内部存在较多的工艺型气孔和冶金型气孔;激光离焦量大于+5 mm时,激光焊接模式为热导焊,焊缝内部气孔率显著降低。随着焊接速度的提高,气孔上浮速度可能低于熔池凝固速度,导致内部气孔率增加。降低焊接速度、采用N2保护气和采用尾吹吹气方式均有助于降低微泵焊缝气孔率。

太阳能-空气双热源热泵系统性能实验

将平板微热管光伏光热组件改造为新型光伏光热蒸发器,研发新型太阳能-空气双热源热泵系统,对太阳能供热模式和双热源供热模式下系统的运行性能进行研究。研究表明:受太阳辐射和环境温度影响,双热源供热模式下环境空气的作用会在放热和吸热之间转换,环境温度与背板温度的温差在-3.1~3.5℃之间波动;双热源供热模式适合在低辐照条件下运行,其热效率、综合性能效率和COP分别达56.7%、81.7%和2.38,比太阳能供热模式提升20.3%、25.0%和6.7%;在高辐射条件下,双热源供热模式会造成系统散热加快,但是对系统发电性能有提升作用。根据上述特性,当背板温度小于环境温度时启动双热源供热模式,反之启动太阳能供热模式,可以进一步提升系统的运行效果。

犬累-卡-佩斯病的组织形态学观察

本试验旨在对临床上患累-卡-佩斯病犬的股骨头组织形态学进行观察,对该病的组织病理学变化进行描述。收集中国农业大学动物医院患有累-卡-佩斯病并采取手术切除治疗的犬的股骨头以及正常犬的股骨头,对其进行大体观察,Micro-CT观察股骨头三维微观结构,取股骨头负重区组织进行H.E.染色、甲苯胺蓝染色观察病理变化,扫描电镜观察各组股骨头骨显微结构变化。结果显示,病变组较正常组股骨头结构破坏严重,组织结构疏松、易于凿切,髓腔脂肪细胞增大增多,骨小梁在塌陷、溶解的同时,伴有新小梁骨的形成。