Performance of truncated surface asperities in elastohydrodynamic lubrication

The elastohydrodynamic lubrication in a sliding line contact between a flattened rough plane surface and a smooth plane surface is analytically studied. Both surfaces are assumed as elastic and parallel to one another. The flattened rough surface is treated as equivalent to a rough plane surface with uniformly distributed cylindrical asperities evenly truncated on the top. For understanding the elastohydrodynamic lubrication performance between these two plane surfaces, an inlet zone analysis is taken for the elastohydrodynamic lubrication formed between a truncated cylindrical asperity and the smooth plane surface. It is found from the obtained results that the asperity truncation reduces the elastohydrodynamic load-carrying capacity, and this effect is significant for low sliding speeds or/and heavy loads, while it is negligible for high sliding speeds and moderate loads. The asperity truncation increases the friction coefficient of the asperity contact especially at relatively light loads, while it only slightly increases the friction coefficient of the asperity contact at heavy loads. For heavy loads, the asperity truncation can have a significant effect on the reduction in the maximum surface temperature rise. It is recommended by the present study that the surface asperity be truncated in a certain degree in an elastohydrodynamic contact with high sliding speeds and relatively heavy loads because of giving the benefits of considerably reducing the maximum surface temperature rise while maintaining the elastohydrodynamic load-carrying capacity.     

单晶金刚石机械研磨结合化学辅助机械抛光组合加工工艺

单晶金刚石因具有最高的硬度和最低的摩擦系数常被用来制备超精密刀具,而表面粗糙度是影响刀具寿命的重要指标.提出采用机械研磨结合化学辅助机械抛光的组合工艺抛光单晶金刚石.实验优化并确定的加工工艺如下:先用5μm和2μm金刚石粉研磨单晶金刚石表面,然后采用化学机械的方法去除机械研磨带来的损伤.用该工艺抛光单晶金刚石,表面粗糙度Ra可达0.8 nm(测量区域70μm×53μm).表面拉曼光谱分析表明化学机械抛光的表面只有1 332 cm-1拉曼峰.     

Waveguide image slicer

A new image slicer with a simple structure has been developed for use in grating spectrometers. The image slicer has polished thin glass plates that work as optical waveguides. It has a square 0.5 mm x 0.5 mm input surface and a steplike output surface with a width of 50 mum that is thin enough for high spectral resolution measurement. The output surface is in the same plane as the input surface so that optical path differences between the plates do not affect the spectrometer optics. The image slicer is efficient, with optical systems with F ratios faster than 10, and can be used at wavelengths that range from visual (lambda = 0.4 mum) to the near infrared (lambda = 2 mum).     

Concave reflective SU-8 photoresist gratings for flat-field integrated spectrometers

On-chip spectrometry will play a leading role in the development of micro-optofluidic systems for analytical chemistry. Integrated spectrometers fabricated using a polymer-on-silicon platform have been designed, fabricated, and characterized. Reflective grating designs have been implemented using a recursive algorithm to calculate the facet positions as described by McGreer [Appl. Opt. 35, 5904 (1996)]. It is shown that the free spectral range, the output focal plane geometry, and the linear dispersion can be selected with a high degree of control independently of the chosen grating order. The polymer-on-silicon platform facilitates integration with microfluidic circuits and cost-efficient batch fabrication.     

Design of an in-line, digital holographic imaging system for airborne measurement of clouds

We discuss the design and performance of an airborne (underwing) in-line digital holographic imaging system developed for characterizing atmospheric cloud water droplets and ice particles in situ. The airborne environment constrained the design space to the simple optical layout that in-line non-beam-splitting holography affords. The desired measurement required the largest possible sample volume in which the smallest desired particle size (～5 μm) could still be resolved, and consequently the magnification requirement was driven by the pixel size of the camera and this particle size. The resulting design was a seven-element, double-telecentric, high-precision optical imaging system used to relay and magnify a hologram onto a CCD surface. The system was designed to preserve performance and high resolution over a wide temperature range. Details of the optical design and construction are given. Experimental results demonstrate that the system is capable of recording holograms that can be reconstructed with resolution of better than 6.5 μm within a 15 cm(3) sample volume.     

Hierarchical 3D SERS Substrates Fabricated by Integrating Photolithographic Microstructures and Self‐Assembly of Silver Nanoparticles

Most of the surface‐enhanced Raman scattering (SERS) substrates are 2D planar systems, which limits the SERS active area to a single Cartesian plane. Here, we fabricate 3D SERS substrates with the aim to break the traditional 2D SERS active area limitation, and to extend the SERS hotspots into the third dimension along the z‐axis. Our 3D SERS substrates are tailored with increased SERS hotspots in the z‐direction from tens of nanometers to tens of micrometers, increasing the hotspots in the z‐direction by at least an order of magnitude larger than the confocal volume (～1 μm) of most Raman spectrometers. Various hierarchical 3D SERS‐active microstructures are fabricated by combining 3D laser photolithography with Langmuir‐Blodgett nanoparticle assembly. 3D laser photolithography creates microstructured platforms required to extend the SERS‐active area into 3D, and the self‐assembly of Ag nanoparticles ensures homogeneous coating of SERS‐active Ag nanoparticles over the entire microstructured platforms. Large‐area 3D Raman imaging demonstrates that homogeneous signals can be collected throughout the entire 3D SERS substrates. We vary the morphology, height, and inclination angles of the 3D microstructures, where the inclination angle is found to exhibit strong influence on the SERS signals. We also demonstrate a potential application of this hierarchical 3D SERS substrate in information tagging, storage and encryption as SERS micro‐barcodes, where multiple micro‐barcodes can be created within a single set of microstructures.     

改性脂类分子自组装微管模板的制备及金属化

利用联乙炔基甘油磷脂酰乙二醇分子自组装制备了脂类微管,并以该脂类微管为模板,在其表面化学沉积制备了镀镍金属微管。SEM和TEM观察表明,自组装微管的生成率很高,脂类微管呈弯曲螺旋结构,具有很高的长径比,平均长度为380μm,平均直径为110 nm;金属微管表面相对致密,平均长度为120μm,平均直径为210 nm。XRD分析结果表明,镍镀层为非晶态结构。金属微管可用作载体包埋海洋防污剂或药物,控制它们的释放,可望用于新型功能材料的开发。     

Finite conjugate embedded relay lens hyperspectral imaging system (ERL-HIS)

We present a novel embedded relay lens hyperspectral imaging system (ERL-HIS) with high spectral resolution (nominal spectral resolution of 2.8 nm) and spatial resolution (30 μm×8 μm) that transfers the scanning plane to an additional imaging plane through the internal relay lens so as to alleviate all outside moving parts for the scanning mechanism used in the traditional HIS, where image scanning is achieved by the relative movement between the object and hyperspectrometer. The ERL-HIS also enables high-speed scanning and can attach to a variety of optical modules for versatile applications. Here, we also demonstrate an application of the proposed ERL-HIS attached to a microscopic system for observing autofluorescent images of sliced cancer tissue samples.     

Multiplexed bead-based mesofluidic system for gene diagnosis and genotyping

We have developed a novel multiplexed bead-based mesofluidic system (MBMS) based on the specific recognition events on the surface of a series of microbeads (diameter 250 μm) arranged in polydimethylsiloxane (PDMS) microchannels (diameter 300 μm) with the predetermined order and assembled an apparatus implementing automatically the high-throughput bead-based assay and further demonstrated its feasibility and flexibility of gene diagnosis and genotyping, such as β-thalassemia mutation detection and HLA-DQA genotyping. The apparatus, consisting of bead-based mesofluidic PDMS chip, liquid-processing module, and fluorescence detection module, can integrate the procedure of automated-sampling, hybridization reactions, washing, and in situ fluorescence detection. The results revealed that MBMS is fast, has high sensitivity, and can be automated to carry out parallel and multiplexed genotyping and has the potential to open up new routes to flexible, high-throughput approaches for bioanalysis.     

视网膜前假体中柔性凸起微电极的研制

采用聚对二甲苯（Parylene C）作为结构材料,借助微细加工技术设计并制作了按6×6矩阵排布的柔性凸起微电极阵列．微电极直径为80μm,引线线宽40μm,电极间距为280μm,引线间距为80μm．电极位点高度约为10μm,呈明显的圆滑凸起结构特征．电极和引线表面均平整光滑,轮廓清晰,结构完好．阻抗测试结果表明：随着频率的增加,凸起微电极的阻抗呈下降趋势,显示出明显的高通特性;1kHz时凸起微电极的阻抗约为10kΩ,较具有相同基底面积的平面电极约低30％,有助于提高电极的信噪比,可望用于视网膜前假体中．柔性凸起微电极制作工艺简单,利于高效率批量制作并提高微电极的集成度．     

Off-plane anastigmatic imaging in Offner spectrometers

In this paper, the imaging performance of an Offner concentric imaging spectrometer is analyzed when the spectrometer entrance slit is disposed arbitrarily on the plane that is parallel to the grating grooves and contains the common center of curvature. Astigmatism-corrected designs are obtained for off-plane incidence on the grating if one point on the slit is located on the Rowland circle of the primary mirror. In this case, the combined system of primary mirror plus diffraction grating provides two astigmatic line images oriented parallel and orthogonal to the plane of diffraction, with the former located on the same plane as the slit. Consequently, these images can be brought to a single focus on this plane by the tertiary mirror if its radius of curvature is chosen properly. In addition, coma aberration is simultaneously removed. These results can be applied to the design of two-mirror or three-mirror spectrometers, generalizing the concept of the best imaging circle and providing solutions to get anastigmatic imaging for two object points and two wavelengths.     

一种彩色大面阵航空遥感相机前向像移补偿机构设计及精度分析

提高彩色大面阵航空遥感相机地面分辨力需设计像移补偿环节以消除工作时CCD像面的像移,本文在分析航空遥感器4种像移补偿方式及像移补偿机构设计原则的基础上,针对某航空遥感器的要求设计了一种前向像移补偿机构,利用等径共轭凸轮机构将电机旋转转化为直线运动,并配合精密直线导轨约束运动自由度。具有传动简单,精度较高的优点,可有效的避免传动误差。分析了原动件输入速度波动、制造误差对像移补偿残差的影响,并对像移补偿总体效果进行了评价。试验数据及数据分析表明,像移补偿机构的补偿残差小到600μm/s,动态目标发生器及外场航拍图像良好,满足使用要求。     

A combined ion probe/spark source analysis system

Spark source mass spectrometry and secondary ion mass spectrometry have complementary advantages in the elemental analysis of solids. The AEI IM20 ion probe and MS702R mass spectrometer form a composite instrument incorporating both techniques; the design and different operating modes are described. A primary ion beam diameter as low as 2 μm can be obtained under favourable circumstances; the minimum detectable concentration of a typical element is derived as a function of this diameter. The mass resolution is greater than 5000 (10% valley definition) with electrical detection and 10,000 (50% density definition) with photographic detection; this resolution is much higher than that obtained with other secondary ion mass spectrometers. Two typical applications illustrate that such high mass resolution is a necessary prerequisite to quantitative interpretation in secondary ion mass spectrometry: precise isotopic analysis of titanium is demonstrated and the concentrations of impurity transition elements derived from ion probe and spark source analyses of a geological olivine are compared.     

等径共轭调焦凸轮机构的精度分析及优化设计

为保证航空遥感器的成像质量,对遥感器偏移的焦平面进行校正,设计了等径共轭凸轮调焦机构.研究了影响凸轮机构精度的因素,分析了滚子径向跳动误差、凸轮加工误差、基圆半径对机构位移正确度的影响,并提出了一种基于最小二乘法,保证凸轮共轭等径、消除机构空回误差及防止机构卡死的优化方法.优化设计了某等径共轭调焦凸轮机构并对其进行了精度分析.结果表明,等径共轭凸轮机构的最大位移误差为主±4.7μm,最大空回误差为4.8μm,机构运行稳定可靠.     

Rapid Prototyping of Microfluidic Systems in Poly(dimethylsiloxane)

This paper describes a procedure that makes it possible to design and fabricate (including sealing) microfluidic systems in an elastomeric material [Formula: see text] poly(dimethylsiloxane) (PDMS) [Formula: see text] in less than 24 h. A network of microfluidic channels (with width >20 μm) is designed in a CAD program. This design is converted into a transparency by a high-resolution printer; this transparency is used as a mask in photolithography to create a master in positive relief photoresist. PDMS cast against the master yields a polymeric replica containing a network of channels. The surface of this replica, and that of a flat slab of PDMS, are oxidized in an oxygen plasma. These oxidized surfaces seal tightly and irreversibly when brought into conformal contact. Oxidized PDMS also seals irreversibly to other materials used in microfluidic systems, such as glass, silicon, silicon oxide, and oxidized polystyrene; a number of substrates for devices are, therefore, practical options. Oxidation of the PDMS has the additional advantage that it yields channels whose walls are negatively charged when in contact with neutral and basic aqueous solutions; these channels support electroosmotic pumping and can be filled easily with liquids with high surface energies (especially water). The performance of microfluidic systems prepared using this rapid prototyping technique has been evaluated by fabricating a miniaturized capillary electrophoresis system. Amino acids, charge ladders of positively and negatively charged proteins, and DNA fragments were separated in aqueous solutions with this system with resolution comparable to that obtained using fused silica capillaries.     

刚体面内位移激光散斑测量研究

运用散斑统计理论,结合数字图像处理技术,设计了一套激光散斑测量刚体面内微小位移的实验系统,再利用刚体位移前后的散斑图像的互相关性,实现了刚体面内的位移测量.测量结果表明,针对刚体面内小于300μm的微小位移,x轴和y轴的绝对位移误差为±14μm,相对误差为±6.25%左右.     

Automatic Inspection of Photographic Materials

An infra-red laser scanning instrument has been developed for the automatic inspection of unexposed photographic strip products (film and paper) for visible defects. The system has been developed jointly by Sira and Kodak and one unit has been in constant use in an on-line application for over 2 years. The laser scanning head is designed to inspect web with a width of up to 1500 mm at line speeds up to at least 100 m/min. Scratches of width down to 50 w m running along the strip, and certain other defects such as digs down to 300 w m in diameter, can be detected. The basic optical principle is to scan an infra-red laser beam with a mirror drum scanner sequentially across the inspected surface, from which the specularly reflected light is collected by a large cylindrical mirror and directed at a photomultiplier detector. When defects in the surface are scanned the photomultiplier signal is temporarily increased or decreased, and it is these features which are extracted by the electronic signal processing units. The output from the instrument can be displayed on an oscilloscope in the form of a ‘videoprint’ (which is a picture of the web surface showing only defects); a permanent ‘videoprint’ can be recorded on a photographic hard-copy instrument.     

针刺毡C/C复合材料磨擦制动压力和速度特性

用模拟刹车制动的摩擦试验机,研究探讨了一种针刺毡结构C/C复合材料在不同制动压力和制动速度下的摩擦磨损性能,并用扫描电子显微镜对摩擦表面进行了观察和分析。摩擦磨损机理由磨屑经挤压、剪切堆积在表面形成的磨屑层所决定。在5m/s制动速度或静态条件下,表面温度低(<150~200℃)吸附水气未脱附,其润滑作用导致了较低的摩擦系数值;当制动速度达到10m/s,摩擦使表面温度升高,达到了吸附水气脱附温度,引起摩擦系数急剧升高,达到了最大;此后,随制动速度及表面温度的继续升高,磨屑层间剪切强度降低,导致摩擦系数随之下降。在较高制动速度下,该种材料仍能保持较高的摩擦系数,显示出优良的高温高能摩擦性能。     

Effect of inherent anisotropy on acceleration wave speeds in hypoplasticity

Generally, soils possess an inherent fabric with transverse isotropy on the bedding plane. As a consequence, the deformation-stress characteristics show a dependence on the loading direction. Anisotropy is characterized by a vector normal to the bedding plane. In this paper we investigate the speeds of acceleration waves in an inherently anisotropic hypoplastic material. For the incrementally nonlinear hypoplastic constitutive equation the wave speed spectrum is continuous in contrast to discrete spectra in incrementally linear constitutive models. The so-called flutter instability arises when the equation for the wave speeds has complex solutions. In the principal stress space, a surface of first occurrence of flutter instability can be identified by analogy with the failure surface defined by a vanishing stress rate. We analyse the influence of the anisotropy on these surfaces and the change in their shape and symmetries depending on the bedding angle.     

基于表面应力的生物传感器敏感元件研制（英文）

基于表面应力的生物传感器利用分子间的结合能来测试生物信号,传感器敏感元件在整个传感器系统中起着决定性作用.研制了一种新型的基于表面应力的传感器,设计、制造了参数为500μm×500μm×1μm的PDMS微薄膜作为敏感元件,并对其进行测量.实验结果表明该薄膜作为敏感元件可以用来探测大肠杆菌.