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).     

Phase-aberration correction using signals from point reflectors and diffuse scatterers: measurements

A method for phase-aberration correction of phased-array images is tested using a model of near-field velocity inhomogeneities. A set of grooved room-temperature vulcanizing plates was constructed to simulate near-field aberrations encountered in clinical ultrasound imaging. As expected, large image distortion was experienced when grooved plates producing significant aberrations were placed near the surface of the array. An iterative aberration correction procedure based on cross-correlation measures between neighboring elements in a phased array, using signals reflected from diffuse scatterers, significantly reduced the effects of these aberrations, producing images nearly identical to those generated in the absence of aberrations. The results suggest that a practical phase-aberration correction system can be constructed for medical ultrasound imaging and possibly all coherent imaging systems by using a sampled aperture.     

柔印橡胶版和感光树脂版印刷性能对比实验

目的比较柔印感光树脂版和橡胶版的表面特性,分析影响版材油墨传输性能和图像再现的原因。方法通过表面能、硬度和粗糙度来表征印版的表面特性,制作相同加网线数的2种版材;在相同的印刷条件下,通过分光光度计和显微镜分析2种版材的油墨转移和图文再现特性。结果感光树脂版表面能比橡胶版高,但橡胶版表面粗糙度比感光树脂版大。从印刷效果来看,感光树脂版的油墨转移效果更好,实地油墨密度更高,而橡胶版的网点扩大程度更小。采用UV油墨印刷时,感光树脂版的印刷反差略高,而采用水性油墨印刷时,两者的印刷反差基本相同。此外,橡胶版比感光树脂版可实现更精确的线条和文字。结论针对特定柔性版,可通过分析研究印版的表面特性,为印刷工艺合理选择版材。     

Image plates for registration of far-ultraviolet spectra

We have tested an autoradiographic photostimulable phosphor image storage plate as a medium for recording spectra in the wavelength region from 50 to 550 A and have compared the results with spectra obtained with conventional photographic emulsions. The image plate shows sensitivity comparable with the photographic plates but has a linear intensity response over a much wider dynamic range. Resolution of current image-plate systems is limited by the scanner that reads the stored image from the phosphor plate, but this limitation is not fundamental. These initial results suggest that optimized image plates with an improved scanner would provide a favorable alternative to photographic plates in this spectral region.     

Technique for detecting flaws in metallic surfaces using an optical system with phase-type blazed gratings

In this paper, we evaluate a novel flaw-detection technique for metallic surfaces based on the use of phase-type blazed gratings. Transparent blazed gratings were prepared by the soft nanoimprint method involving the transfer of a template (a reflective grating structure used for spectroscopy) onto silicone rubber. The blazed gratings were then integrated into an imaging system to observe the reflective metal sample. Due to the low-pass-filtering properties of the gratings, the captured image was notably blurred. This characteristic aids in flaw detection on metallic surfaces because the captured image is adequate to distinguish flaws in the targeted area on the basis of the texture of the rough surface, including any other structures that were unintended. The use of double-sided gratings with crossing grating vectors was found to be efficient for homogenous low-pass filtering. Such flaw-detection techniques are expected to be useful for conducting quality inspections of rolled steel plates since the surface contains both a rough surface and undesirable flaws.     

Enhanced osteoblast and osteoclast responses to a thin film sputtered hydroxyapatite coating

A sputtering technique followed by a low temperature hydrothermal treatment has been demonstrated to produce a dense-and-bioactive hydroxyapatite thin film coating. The purpose of the present study was to investigate osteoblast and osteoclast responses to the hydroxyapatite coated plates and titanium plates with similar roughness. Rat bone marrow stromal cells were cultured on these plates to induce osteoblasts. The cells showed a significantly enhanced proliferation on the hydroxyapatite surface, accompanied by increase of osteoblastic phenotypes. The co-cultured osteoclasts exhibited the significantly different cell number and morphology between the hydroxyapatite and the titanium surfaces. A series of osteoclast marker genes were more stimulated on the hydroxyapatite and thirty two percent of the hydroxyapatite surface area could be resorbed by osteoclasts. The thin film sputtered hydroxyapatite could provide a favorable surface for both osteoblast and osteoclast formation and their function, indicating its good osteoconductivity and biodegradability.     

具有不同浸润性功能有机表面薄膜的制备

通过开发的有机镀膜技术,选用具有不同功能基团的有机镀液对不锈钢表面进行改性.借助于红外光谱、接触角和表面自由能等测试对有机镀膜处理的不锈钢表面薄膜进行了表征.实验结果表明,经过TTN溶液有机镀膜后,不锈钢表面自由能升高、蒸馏水接触角减小,具有了亲水功能特性;而经过DHN和AF17N溶液有机镀膜处理后,其表面自由能降低、蒸馏水接触角增大,具有良好的疏水功能特性;其中经过AF17N镀液处理后表面自由能最小而接触角最大,即疏水效果最佳.该技术实现了不锈钢表面的亲/疏水表面改性,提供了一种制备具有不同浸润性的有机表面薄膜材料的方法.     

Tonpilz piezoelectric transducers with acoustic matching plates for underwater color image transmission

Tonpilz piezoelectric transducers with multiple acoustic matching plates are suitable for color image acoustic transmission, to achieve wideband low-ripple characteristics as well as high-efficiency high-power transmitting capability. The design method for the transducers was investigated on the basis of multiple-mode filter synthesis theory. For transducers with single, double, and triple matching plates, optimum specific acoustic impedances and lengths were calculated. Moreover, based on this design method, a 24 kHz array comprising nine identical transducers with single matching plates was built and evaluated. As a result, this array showed high-efficiency, low-ripple, and wideband characteristics. Excellent agreement between theoretical values and experimental results was obtained. A field test was carried out on color image transmission from a 3500 m sea depth, using the fabricated array, during which good color images were received.     

Service life prediction for refractory materials

Ultrasonic pulse velocity testing and image analysis were used to predict the thermal stability of cordierite–mullite refractories. Two compositions used as substrates in fast firing of porcelain whiteware, characterized by different microstructure and crack propagation behavior, were investigated. Fracture strength and fracture toughness values were obtained from three point bending test and chevron notched specimen technique, respectively. The measurement of the ultrasonic velocity was used to assess the material degradation with increasing number of thermal-shock cycles and specimen damage was monitored using image analysis to obtain further evidence of material degradation. The correlation between thermo-mechanical properties, ultrasonic velocity, microstructure, crack-propagation behavior and thermal-shock resistance was discussed. A remarkable similarity was found between the variation of ultrasonic velocity (when measured through the length of the refractory plates) and fracture strength with number of thermal shock cycles. On the other hand, the development of surface microcracking, as monitored by image analysis, is in good agreement with the variation of K _IC with the number of thermal-shock cycles. The variation of the ratio with number of thermal-shock cycles shows the highest gradient of the investigated trends and it is proposed as a promising parameter to differentiate refractory materials regarding their different thermal shock behavior. Service life prediction models for refractory plates, from measured values of ultrasonic velocity and surface damage analysis, were proposed and validated.     

Ti-WC nanocrystalline coating formed by surface mechanical attrition treatment process on 316L stainless steel

Nanocrystalline coatings were performed on the surface of 316L stainless steel plates mechanically with a mixture of Ti and WC powders under vacuum conditions. The targets were replaced in the end of the high energy milling rig, while Ti-WC mixture was milled as usual. It is shown that the coatings are nanocrystalline in nature with narrow distribution of average size of nanocrystallites. X-ray diffraction and scanning electron microscopy (with energy-dispersive spectrometer) revealed that the top layer of the coatings is uniform. Microhardness, roughness and primary corrosion tests (tafel tests) proved enhancement of coated samples with respect to raw materials. Transmission electron microscope image of deformed surface confirmed surrounding of nanoparticles by dislocation loops after plastic deformation.     

Design, fabrication, and evaluation of microfabricated columns for gas chromatography

The design, fabrication, and performance of gas chromatography columns etched in silicon substrates are described. Deep reactive-ion etching formed the 3-m-long, 150-microm-wide, 240-microm-deep rectangular cross section channels. A glass cover plate was anodically bonded to the remaining surface of the substrate forming the gastight channel. For some of the columns, the silicon channels were oxidized before the channels were sealed with the glass plates. Fused-silica capillary connecting tubes were sealed into ports on the edge of the 3.2-cm x 3.2-cm substrate chips. Dynamic coating was used to deposit a film of nonpolar dimethyl polysiloxane or moderately polar trifluoropropylmethyl polysiloxane stationary phase. The columns were evaluated in a conventional benchtop GC instrument with split injection and flame ionization detection. Column efficiency was evaluated by the use of plots of height equivalent to a theoretical plate versus average carrier gas velocity using both hydrogen and air as carrier gases. The number of theoretical plates measured at the average carrier gas velocity giving the minimum plate height ranged from 4600 to 8200 plates for the dimethyl polysiloxane columns and from 3500 to 5500 plates for the trifluoropropylmethyl polysiloxane columns. Minimum plate height was significantly smaller with air as carrier gas. For the nonpolar phase, the nonoxidized surface gave approximately 1500 plates more than the oxidized surface for both carrier gases. For the polar phase, the oxidized surface gave approximately 200 plates more than the nonoxidized surface. Isothermal chromatograms of a 20-component multifunctional mixture and temperature-programmed chromatograms of a normal alkane mixture are presented.     

Analysis of orthotropic thick plates by meshless local Petrov–Galerkin (MLPG) method

A meshless local Petrov–Galerkin (MLPG) method is applied to solve static and dynamic problems of orthotropic plates described by the Reissner–Mindlin theory. Analysis of a thick orthotropic plate resting on the Winkler elastic foundation is given too. A weak formulation for the set of governing equations in the Reissner–Mindlin theory with a unit test function is transformed into local integral equations on local subdomains in the mean surface of the plate. Nodal points are randomly spread on the surface of the plate and each node is surrounded by a circular subdomain to which local integral equations are applied. The meshless approximation based on the Moving Least–Squares (MLS) method is employed in the numerical implementation. The present computational method is applicable also to plates with varying thickness. Numerical results for simply supported and clamped plates are presented. Copyright © 2006 John Wiley & Sons, Ltd.     

Impact surface fractures of glass-fiber/epoxy lamina-coated glass plates by small steel-ball

Fiber orientation effects on the impact surface fracture of glass plates coated with a glass-fiber/epoxy lamina layer were investigated using a small-diameter steel-ball impact experiment. Four kinds of materials were used: soda-lime glass plates, unidirectional glass-fiber/epoxy layer (one ply, two plies) coated glass plates, crossed glass-fiber/epoxy layer (only two plies) coated glass plates. The maximum stress and absorbed fracture energy of these plates were measured by a single-grid strain gage bonded to the back surface of the glass plates during the impact of the steel ball. With increasing impact velocity, various surface cracks, such as ring, cone, radial and lateral cracks, occurred near the impact sites of the uncoated glass plates. Plates with glass-fiber coating had a plastic deformation zone between the fiber layer and the glass plate that formed around the impact site while the surface cracks in the plates drastically diminished. The principal direction of this plastic deformation and delamination followed the fiber orientation. The impact surface-fracture index expressed in terms of the maximum stress and the absorbed energy could be used as an effective evaluation parameter for surface resistance.     

Effects of face plates on surface displacement profile in 2-2piezoelectric composites

A simple model is developed to describe the inhomogeneous surface deformation profile of face plated 2-2 type piezocomposites. The contribution of face plate to the equilibrium condition is approximated by simple elastic bending of the plate. Analytical solutions were obtained for the inhomogeneous surface displacement profile. From these solutions one can predict the variation of the nonuniform surface displacement in a 2-2 composite with respect to material and geometry parameters. It is shown that the surface displacement uniformity depends on several factors: the ceramic aspect ratio, the spacing between ceramic plates, the thickness of face plate, the Young's modulus of the polymer and of the face plate. The calculated results indicate that stiffer face plates, softer polymer resin, and closer ceramic spacing could make the piezocomposite transducers have more uniform surface displacement     

变换域加密全息水印算法

提出了一种基于DCT-DWT的彩色图像全息水印算法。为了保证水印信息的安全性,该算法首先对水印信息进行双随机相位调制,并生成水印全息图;其次,将载体图像在Lab空间内的L分量进行4×4分块,对每一分块进行DCT变换,抽取每个矩阵的中低频系数,组成一个新的矩阵,并对之进行小波分解,将水印全息图嵌入到它的中低频小波系数上。实验结果表明,基于DCT-DWT变换的水印算法具有较好的不可见性,对常见的攻击具有强鲁棒性。     

彩色印刷套准误差的自动检测研究

用线阵 CCD 作为探测元件,对印张的十字线套印标记进行自动扫描。 采用交替处于 CCD 光敏面之前的红、绿、蓝 3 种滤色片来识别十字套准线的色彩,并根据加不同滤色片 CCD 输出电平的不同来判别 CMYK 印版的偏移方向。 实现了并行比较 A / D 变换电路对 CCD 输出电平进行 A / D 转换,并以代码形式在显示器上显示相应印版的套准误差及方向。     

基于比例特征的区域分割算法在药板缺陷检测中的研究

目的 为解决铝塑泡罩药板图像ROI区域定位慢、精度差等问题,本文提出一种基于比例特征的泡罩区域分割算法,该算法可以快速定位并分割泡罩ROI区域,结合图像相关性特征算法对铝塑泡罩药板进行缺陷检测。方法 首先通过工业相机采集药品包装生产线上的药板原始图像,接着使用Blob分析从原始图片中分离出铝塑泡罩主体部分,然后通过仿射变换将图像放置在中心区域,并使用比例特征分割算法对泡罩区域进行分割,最后通过金字塔加速的NCC算法完成缺陷检测。结果 实验结果表明,基于比例特征分割后的图像平均NCC匹配时间为9 ms,在缺陷样本占比20%的实验中误检率为0.167%,漏检率为0.556%。结论 通过比例特征分割出精准的泡罩ROI区域结合改进的NCC算法,在拥有较高准确率的同时大幅减少了缺陷检测时图像匹配的时间,能较好地完成铝塑泡罩药板的缺陷检测任务。     

Some examples of nondestructive flaw detection by shearography

This paper presents some examples of nondestructive flaw detection using an optical method based on speckle shearing interferometry called shearography. In the method, a structure under study is illuminated by laser and imaged by a special image-shearing camera. After suitable processing, a fringe pattern which represents loci of surface displacement derivatives, i.e., strains, is observed in the image. Since defects in structures usually induce strain concentrations around them and since strain concentrations usually cause perturbations on the surface of structures, shearography reveals defects from anomalies in the recorded fringe pattern. In this work, the technique has been applied to the nondestructive detection of various flaws in plain and welded pipes, composite plates, and other engineering components. A simple model was also developed for the estimation of the depth of disbonds in glassfiber reinforced plastic sheets. Results obtained are good and demonstrate the usefulness of the method as a complement to other conventional NDT techniques.     

A high-throughput, low-volume enzyme assay on solid support

A high-throughput enzyme assay is described that uses 1 microL or less of enzyme solution for each test. Enzyme solutions are deposited by robotic handling in a throughput of over 1000 tests/h on the surface of silica gel plates that have been preimpregnated with fluorogenic substrates. The reaction is quantitated by fluorescence. The method is compatible with water-insoluble substrates (lipases), water-soluble substrates (glycosidases), whole-protein substrates (proteases), and enzyme inhibition measurements. Hydrolytically labile umbelliferyl esters can be used to assay lipases in this format without background hydrolysis. High throughput and reproducibility were tested by fingerprint analysis of lipases and esterases against 37 different fluorogenic ester substrates. A set of eight fluorogenic unbelliferyl esters was selected for optimal activity screening of lipases and esterases on silica gel plates.     

Lamb wave excitation by Hertzian contacts with applications in NDE

Excitation of Lamb waves in solid plates by point-like Hertzian contacts for material characterization and nondestructive testing is investigated. A 2 dimensional model using normal mode theory is used to predict the relative excitation efficiency of the lowest order Lamb waves in anisotropic solid plates. Hertzian contact transducers with PZT-5H piezoelectric material and quartz buffer rods are realized to operate in the 200 to 500 kHz range for experimental verification. Single mode operation with the lowest order antisymmetric Lamb wave (A ₀) mode is achieved in various plates at in agreement with theoretical predictions. The technique is applied for material characterization on single crystal silicon samples and defect detection in composite plates. The phase velocity anisotropy of the A₀ mode is measured with signal-to-noise levels exceeding 65 dB. In (111) cut silicon plates the absolute phase velocity is measured with ±0.05% accuracy. The phase velocity anisotropy and effects of delamination in layered composite plates are calculated using the surface impedance approach. The experiments on graphite/epoxy composite plates agree with these calculations and show the potential of the method for defect detection with high resolution