光学显微镜自动聚焦的技术研究

在对普通光学显微镜进行一定改装的基础之上 ,设计了一套显微镜自动聚焦系统 ,并且给出了图像的灰度差分绝对值之和算子 ,解决了自动聚焦过程中是否正确聚焦的判断问题。最后还给出了一套基于启发式搜索算法的聚焦搜索策略 ,以加快焦平面的搜索。     

Measurement of surface roughness: Comparison between a defect-of-focus optical technique and the classical stylus technique

Talysurf 5 measurements and defect-of-focus optical measurements are compared by statistical analysis and three-dimensional imaging for various metal surface roughnesses. The results show the interest of the new non-destructive technique for roughnesses R_t ranging from 0.1 to 20 μm.     

螺旋叶片血泵血液流动性能分析

根据人体血液的流变特性,对血液在低剪变率及高剪变率两种不同条件下的环形空间螺旋流动性能进行了研究,推导出速度及流量表达式,分析了各参数对流动性能的影响,对螺旋叶片血泵的设计和研究具有重要的参考价值。     

枪钻技术在柱塞泵转子加工中的应用

介绍了枪钻头的主要参数、工作原理 ,其中重点介绍了枪钻主要几何参数的选择范围 ;还介绍了油泵转子柱塞孔枪钻床的主要结构、加工范围、主要工装及加工效果 ,对其主要工装的相互配合关系及作用作了详细分析并给出一些重要参数 ,如配合间隙等 ;最后以某型转子为例作了具体说明     

污水源热泵应用关键技术浅析

简要介绍污水源热泵的工作原理及基本形式,概述污水源热泵优越性。着重探讨了污水源热泵的阻塞污染、流动换热及其如何达到有效防污除污的问题。     

A comparison of optical geometries for combined flash photolysis and total internal reflection fluorescence microscopy

Total internal reflection fluorescence (TIRF) microscopy, used in conjunction with flash photolysis, provides a useful way of investigating the kinetics of macromolecular interactions. We compare different TIRF optical geometries to establish an optimal combination. Excitation light was introduced via four different arrangements: (1) a prism positioned on the microscope optical axis, (2) an offset prism with propagation through a silica slide trans to the objective lens, (3) an offset prism with propagation through a silica coverslip cis to a water-immersion objective lens and (4) a prismless arrangement using a high NA oil-immersion objective lens. Photolysis was achieved using a Xe flash lamp and a customised silica condenser lens. Single myosin molecules labelled with a Cy3 fluorophore were used as a test sample. Although the offset trans prism gave the best signal-to-background ratio, a customised thin rhombic prism incorporated, on axis, into the flash condenser assembly was almost as good and was more practical for scanning multiple fields. An oil-immersion lens gave the brightest image for sample depths < 30 µm but above this limit, a water-immersion lens was better. The prismless arrangement may offer advantages in other situations but it is important to check the actual numerical aperture of the objective lens.     

A nanosecond optical parametric oscillator in the mid-IR region with double-pass pump

An optical parametric oscillator (OPO) with double-pass pump based on MgO:PPLN and PPLN periodic structures is described. A compact nanosecond Nd:YLF laser has been used as a pump source at 1.053 μm (the pumping pulse duration is 5–7 ns at a maximum pulse energy of 300 μJ at frequencies of 1–7 kHz). The oscillation threshold of the OPO based on MgO:PPLN was varied in a range of 11–28 μJ at wavelength of 2.1–4.3 μm. The conversion efficiency from the pump wave to an idler wave decreased from 8.6 to 2.5% in the range of 2.0–4.3 μm. For PPLN-OPO the measured threshold was 36 μJ at 4.2 μm and 49 μJ at 4.7 μm. The conversion efficiency of the pump energy into the energy of an idler wave was 3.3μ-0.4% at wavelengths of 4.2–4.7 μm.     

紧凑型轴流式血泵电机的设计与仿真

针对传统轴流式磁悬浮血泵存在轴向尺寸偏长,不利于植入问题。提出一种将无刷直流电机与径向磁悬浮轴承集成结构,可有效缩短血泵轴向尺寸;在讨论血泵结构的基础上,重点通过对无轴承直流电机进行理论计算,获得其设计参数,然后采用数值仿真,讨论了电流、位移以及转子位置角对无轴承直流电机径向悬浮力的影响关系。     

Measurement and analysis of flow behaviour in complex geometries using the Ultrasonic Velocity Profiling (UVP) technique

In this project a non-Newtonian CMC model fluid was tested in two different complex geometries using Ultrasonic Velocity Profiling (UVP). Velocity profiles were measured at three different positions at the center (contraction) of a specially manufactured 50% open diaphragm valve. The complex geometry coordinates and velocity magnitudes were analysed and compared to the bulk flow rate measured using an electromagnetic flow meter. The difference between the calculated and measured flow rates varied from 15% to 25%. A complete flow map in the axial direction from developed to contracting flow was also measured by scanning the transducer along a hyperbolic contraction using a high precision robotic arm set-up. Experimental results obtained using UVP showed good agreement (10%) with theoretical predictions. Results showed that it was possible, for the first time, to measure quantitative velocity data for non-Newtonian flow in a complex geometry, such as a diaphragm valve. It was found that the most important problem in order to increase measurement accuracy is the estimation of wall interface positions, which is due to the ultrasonic transducer’s near field. This problem can be eliminated by the introduction of a next generation transducer, which is currently under development.     

大型双吸泵泵体的加工艺及误差分析

对大型双吸泵泵体的加工工艺进行了介绍，并对加工过程中可能产生的形位误差进行了分析。     

Visualization of relative flow patterns in centrifugal blood pump

This paper presents computational and flow visualization results on a centrifugal blood pump. 4 impeller designs were tested at a rotational speed of 2000 rpm using blood analog as working fluid. All impellers have seven blades but of different geometry (Impellers A3, A4, B2 and R7). Flow visualization within the impeller passages was conducted using an image de-rotation system. A pair of large scale vortices was found within the blades of impeller R7 while a single vortex was found in most of the passages of backward facing impellers (Impellers A3, A4 and B2). To establish the effects of blade geometry on blood cells, CFD was used to simulate the blade to blade flow to provide an estimate of the maximum shear stress. The results showed that though most of the stresses within the blade passages are below a threshold level of 150 N/m² for extensive erythrocyte damage to occur, there are some regions near to the leading edge of the pressure side where the shear stresses are above threshold level.     

An optical pump-probe technique for measuring the thermal conductivity of liquids

We present a pump-probe optical technique for measuring the thermal conductivity of liquids. The technique uses a reflective geometry which does not depend on the optical properties of the liquid and requires as little as a single droplet to produce a result. An analytical solution is given for bidirectional heat flow in layered media, including the effects of radial heat flow from coaxial Gaussian laser spots, thermal interface resistances, and the accumulation of multiple laser pulses. In addition, several experimental improvements over previous pump-probe configurations are described, resulting in an improved signal to noise ratio and smaller errors at long stage delay times. The technique is applied to a range of liquids and solids. Results are in good agreement with literature values.     

Rapid manufacturing techniques in the development of an axial blood pump impeller

This paper presents a comparison of manufacturing techniques used in the development of an axial blood pump impeller. In this development process the impeller was designed and its performance was evaluated with the aid of computational fluid dynamics (CFD). Prototypes of those designs where the CFD results show promise were needed in sufficient quantities at a low cost for experimental validation of the CFD results. As the impeller is less than 16 mm in diameter with a maximum blade thickness of about 1.5 mm, innovative manufacturing techniques are explored in this paper to determine the best process for quick fabrication of prototypes that are dimensionally accurate, structurally robust and low in cost. Four rapid prototyping techniques were explored. The completed parts were compared on the basis of manufacturing time, quality and strength of parts obtained, manufacturing cost and also in vitro performances. Based on these studies, it was concluded that selective laser sintering (SLS) is the most appropriate method for the quick production of prototype parts for evaluation of pump performance.     

地面驱动螺杆泵井口偏斜对光杆的影响

针对地面驱动螺杆泵井口偏斜的问题，对光杆的载荷和应力进行了分析，并以大庆油田一口螺杆泵井的实际测试数据为例进行了计算，最后指出即使井口偏斜角度很小，也会在光杆内部产生相对较大的弯曲应力。在光杆的设计过程中，应进行疲劳强度校核，并设法提高光杆的疲劳强度。     

Microhaemodynamics within the blade tip clearance of a centrifugal turbodynamic blood pump

A persistent challenge facing the quantitative design of turbodynamic blood pumps is the great disparity of spatial scales between the primary and auxiliary flow paths. Fluid passages within journals and adjacent to the blade tips are often on the scale of several blood cells, confounding the application of macroscopic continuum models. Yet, precisely in these regions there exists the highest shear stress, which is most likely to cause cellular trauma. This disparity has motivated these microscopic studies to visualize the kinematics of the blood cells within the small clearances of a miniature turbodynamic blood pump. A transparent model of a miniature centrifugal pump having an adjustable tip clearance (50-200 microm) was prepared for direct optical visualization of the region between the impeller blade tip and the stationary housing. Synchronized images of the blood cells were obtained by a microscopic visualization system, consisting of an inverted microscope fitted with long-working-distance objective lens (40x), mercury lamp, and high-resolution charge-coupled device camera electronically triggered by the rotation of the impeller. Experiments with 7 microm fluorescent particles revealed the influence of the gap dimension on the trajectory across the blade thickness. The lateral component of velocity (perpendicular to the blade) was dramatically enhanced in the 50 microm gap compared with the 200 microm gap, thereby reducing the exposure time. Studies with diluted bovine blood (Ht = 0.5 per cent) showed that the concentration of cells traversing the gap is also reduced dramatically (30 per cent) as the blade tip clearance is reduced from 200 microm to 50 microm. These results motivate further investigation into the microfluidic phenomena responsible for cellular trauma within turbodynamic blood pumps.     

An opto-isolator based linearization technique of a typical thyristor driven pump

A thyristor driven pump is operated by varying the DC input signal in the firing circuit of thyristor drive. This operation suffers from difficulties due to the nonlinear relation between thyristor output and DC input. In the present paper, an opto-isolator based linearization technique of a typical thyristor driven pump has been proposed. The design, fabrication and the necessary circuit diagram along with theoretical explanations of the resultant output has been described. The operation of the linearized thyristor driven pump has been studied experimentally and the experimental data before and after linearization are reported. The characteristic graphs are found to have very good linearity.     

基于荧光示踪技术的水质稳定剂在线自动监测仪

为了对工业循环冷却水水质稳定剂进行监测与控制,研制了一种基于荧光示踪技术的水质稳定剂在线自动监测仪.通过动态模拟实验,初步验证了系统的有效性.结果表明,仪器运行稳定,性能可靠.     

齿轮泵密封槽铣削加工四工位气动夹具设计

为提高齿轮泵后盖密封槽数控加工效率,设计了一款四工位气动夹具,从精度要求入手,确定了定位方案,分析并设计了定位装置的结构、夹具体的结构、夹紧装置的结构,分析了定位误差,最后进行了夹具的装配和使用,结果表明加工精度稳定、操作方便、加工效率明显提高,实际应用效果良好.     

轴流血泵叶轮结构仿真优化分析

采用CFD仿真技术,结合所设计的微型轴流血泵,对血泵叶轮中的速度、压力、应力等分布进行了仿真分析。研究结果表明：血泵中的流体具有非常复杂的流动情况,为了避免流动分离、压力变化过大等情况,减少剪切应力,对血泵叶轮结构提出了相应的改进意见。     

倾斜下电极式MOEMS光开关阵列的光路分析及准直技术研究

从高斯光束的传输理论出发,对8×8 MOEMS阵列光开关的光路进行了分析.这种光开关的反射镜尺寸与插入损耗(简称插损)密切相关.为了降低插损并且达到准直长度的要求,对相关参数进行了优化选择.此外,开关中光纤、球透镜以及微反射镜之间的位置及角度偏移均会使插损大大增加,采用自对准技术和凸角补偿方法可以有效提高各个器件之间的对准效果,降低插损[1].