Tissue characterization by image processing subtraction: windowing of specific T1 values.

A method for windowing specific T₁ values is presented. A 1.0 T imager with two routine pulse sequences was employed: A T₁-weighted spin echo (SE) sequence and a short tau inversion recovery STIR sequence (fat-suppressed IR). A T₁ window for fat was obtained by subtracting the STIR image from the SE image. Negative values were coded black. The method was tested on a normal human thigh, on a human liver with confirmed fatty infiltration, and on the livers of four live burbots. The fat-containing tissues of the two human volunteers were well depicted. The differences in fat concentration among the burbot livers were also clearly shown. The fat intensity seen in the images correlated well with the chemically measured fat concentration. This subtraction method for windowing T₁ values proved feasible for fat. The method could be used for tissues with other short T₁ values as well.     

远程采集模糊无人机图像的特征识别方法研究

地面对空中无人机的视觉识别中,由于无人机的飞行速度、角度呈现非线性变化。使得采集的疑似图像存在特征模糊、衰退等问题,传统的模式识别方法无法提取无人机图像的主要特征,极大程度上降低了图像的识别概率。提出一种引入球面谐波基图像特征细分的无人机识别算法,建立球面谐波基图像识别模型,利用无人机图像的球面谐波基图像近似率,对模糊图像的差异特征进行依次识别。实验结果表明,利用改进算法建立的模糊无人机图像差异特征识别模型,具有一定的优越性,提高了无人机识别的准确率。     

Determination of solid materials rigidity modulus by a new nondestructive optical method

We propose a new optical method for the determination of the rigidity modulus G of solid materials. The rigidity modulus is determined by measuring the twisted angle θ as a response of the material sample, depending on the applied force. The measuring of this twisted angle can be carried out by using an adapted polarimetric sensor. The effective measurement of rigidity modulus G for aluminum, Plexiglas and steel was experimentally obtained 1.4464×10¹⁰,0.99417×10⁹ and 1.0395×10¹¹ N m, respectively. The study has demonstrated the effective usefulness of our method for evaluating the rigidity modulus. A good agreement between the theoretical and experimental results was achieved.     

Two-dimensional lateral ordering of self-assembled Ge islands on patterned substrates

Stacks of Ge islands layers, separated by thin Si spacer layers, have been grown on prepatterned Si (0 0 1) substrates. The sample topography, obtained by atomic force microscopy, exhibits a regular two-dimensional island arrangement. The vertical alignment is confirmed in cross-sectional transmission electron microscopy images. X-ray diffraction reciprocal space maps around the (0 0 4) Bragg point reveal exceptional lateral and vertical ordering of the Ge islands. Photoluminescence spectra taken at 5 K show well-separated peaks of the no-phonon and the transverse-optical phonon replica of these ordered islands, which is achieved too, due to the excellent island size uniformity.     

Surface modification of ceria nanoparticles and their chemical mechanical polishing behavior on glass substrate

To improve their chemical mechanical polishing (CMP) performance, ceria nanoparticles were surface modified with γ-aminopropyltriethoxysilane (APS) through silanization reaction with their surface hydroxyl group. The compositions, structures and dispersibility of the modified ceria particles were characterized by Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), field-emission scanning electron microscopy (FE-SEM), energy dispersive spectroscopy (EDS), laser particle size analyzer, zeta potential measurement and stability test, respectively. The results indicated that APS had been successfully grafted onto the surface of ceria nanoparticles, which led to the modified ceria nanoparticles with better dispersibility and stability than unmodified ceria particles in aqueous fluids. Then, CMP performance of the modified ceria nanoparticles on glass substrate was investigated. Experimental results showed that the modified ceria particles exhibited lower material removal rate (MRR) but much better surface quality than unmodified ceria particles, which may be explained by the hardness reduction of ceria particles, the enhancement of lubrication of the particles and substrate surfaces, and the elimination of the agglomeration among the ceria particles.     

Synthesis, characterization of ceria-coated silica particles and their chemical mechanical polishing performance on glass substrate

Nano-sized ceria particles were coated on the silica surface by the precipitation method using ammonium cerium nitrate and urea as precipitant with poly(vinylpyrrolidone) (PVP) as assistant. The structures and compositions of ceria-coated silica particles were characterized using X-ray diffraction (XRD), field-emission scanning microscopy (FE-SEM), energy dispersive spectroscopy (EDS), transmission electron microscopy (TEM) and dynamic light scattering (DLS) measurements. The results show that nano-size ceria particles were coated uniformly around the surface of silica particles when PVP was used as assistant during coating process, while without PVP, the ceria particles were grown sparsely on the silica particle surface and many ceria particles grow up through independent nucleation in the solution. Then, the chemical mechanical polishing (CMP) behaviors of the as-prepared ceria-coated silica particles on glass substrate were investigated. The CMP test results suggest that the as-prepared ceria-coated silica particles exhibit higher removal rate than pure silica particles without deteriorating the surface quality. In addition, online coefficient of friction (COF) was conducted during the polishing process. The COF data indicate that the COF values of ceria-coated silica particles are larger than those of pure silica particles due to their surface properties.     

Localized corrosion effects and modifications of acidic and alkaline slurries on copper chemical mechanical polishing

This study demonstrates the CMP performance can be enhanced by modifying the corrosion effects of acidic and alkaline slurries on copper. A corrosion test-cell with a polishing platform is connected with the potentiostat to investigate the corrosion behaviors of copper CMP in various alumina slurries. Experiments show that the slurry needs to be maintained in acidic pH<4.56 or alkaline pH>9.05 surroundings and thus better dispersion of alumina particles and less residual contaminant on copper surface can be obtained. The surface defects after copper CMP using acidic and alkaline slurries are described by pitting corrosion mechanisms, and these mechanisms can be regarded as a basis to modify their corrosion effects. Experimental results indicate that it is necessary to modify the dissolution of HNO₃ and oxidization of NH₄OH for copper CMP slurries. Consequently, the slurries of 5 wt.% HNO₃ by adding 0.1 wt.% BTA or 5 wt.% KNO₃ by adding 1 wt.% NH₄OH achieve good CMP performance for copper with higher CMP efficiency factor (CMPEF), 1460 and 486, and lower surface roughness (R_q), 4.019 and 3.971 nm, respectively. It is found that AFM micrographs can support the effectiveness of corrosion modifications for copper CMP in various slurry chemistries.     

Effects of the ultrasonic flexural vibration on the interaction between the abrasive particles; pad and sapphire substrate during chemical mechanical polishing (CMP)

In this paper, the technique of ultrasonic flexural vibration assisted chemical mechanical polishing (UFV-CMP) was used for sapphire substrate CMP. The functions of the polishing pad, the silica abrasive particles, and the chemical additives of the slurry such as pH value regulator and dispersant during the sapphire's UFV-CMP were investigated. The results showed that the actions of the ultrasonic and silica abrasive particles were the main factors in the sapphire material removal rate (MMR) and the chemical additives were helpful to decrease the roughness of sapphire. Then the effects of the flexural vibration on the interaction between the silica abrasive particles, pad and sapphire substrate from the kinematics and dynamics were investigated to explain why the MRR of UFV-CMP was bigger than that of the traditional CMP. It indicated that such functions improved the sapphire's MRR: the increasing of the contact silica particles’ motion path lengths on the sapphire's surface, the enhancement of the contact force between the contact silica particles and the sapphire's surface, and the impaction of the suspending silica particles to the sapphire's surface.     

基于图像识别技术的随机线缆束建模及分布参数统计分析

提出了一种对实际弯曲随机捆扎线束的建模方法,该方法首先基于图像识别技术,使用实际线束在侧视和俯视方向的两幅照片来实现弯曲线束轴心三维坐标的重建,然后再基于随机转移路径方法实现弯曲线束的捆扎随机性。基于该建模方法,通过蒙特卡洛模拟来分析弯曲随机线束分布参数的统计特征,发现自电感、互电感和互电容均值沿线变化趋势与线束高度变化趋势一致,自电容均值则趋势相反;自电容、自电感和互电感的变异系数与线束高度存在负相关特征;捆扎随机性不会改变自电感和自电容均值,但是会降低互电容与互电感均值。     

Non-linear dynamical analysis of crack surface perturbations and their dependence on velocity and direction

The fracture surfaces of single crystal [1 0 0] silicon specimens, fractured under three-point bending (3PB) and subjected to a high strain energy upon cracking, revealed exceptional surface perturbations, generated during the unstable propagation. While macroscopically the crack is propagating on the (1 1 1) low energy cleavage plane, microscopic examination revealed small angled deviations from and fluctuations along that plane. Furthermore, while the crack is propagating at a velocity of nearly 3000 m/s in the direction, its velocity in the direction is two orders of magnitude lower, with distinctive surface perturbations. The amplitude and complexity of the perturbations increase as the normal velocity vector changes its direction and magnitude. These perturbations were recorded with a profilometer and analyzed using non-linear dynamical analysis tools. This study provides an opportunity to interpret surface phenomena of one of the most general cases of fracture and to study the effect of major variables on the nature of the perturbations involved, such as the local crack tip velocity and the crystallographic orientations. It is shown that the surface perturbations are chaotic deterministic in nature and can be described by high order non-linear differential equations; the order of the equation varying with the variations of the local velocity and direction.     

基于粗测位置和方位的三视场快速星图识别方法

为了在已知粗略方位角和地理位置时实现三视场天文定位定向设备的快速测量,给出了一种三视场定位定向设备的快速局部星图识别方法。分析了三视场定位定向设备使用全天球识别数据库执行三角形识别时识别效率低的原因;指出了应先进行视场内识别,后进行视场间识别以提高效率,并给出星图识别时角距误差门限的选取范围;给出了一种基于粗略位置和方位快速生成局部识别数据库的方法,它可以减少识别信息的冗余,实现高效的星图识别。仿真实验和野外实验结果表明：使用此局部识别方法正确识别率可达99.19%,识别速度为24.3 ms,基本满足三视场天文定位定向设备快速高效测量的要求。验证了局部星图识别方法的效率,以及采用先视场内识别后进行视场间识别方式的正确性。     

基于支持向量机的~(252)Cf中子裂变信号时频特征分析及识别

基于裂变中子(252Cf)对裂变链(235U系统)依存关系,在对252Cf中子裂变信号的测量原理及信号特点分析基础上,开展了基于支持向量机的中子裂变信号时频特征分析及识别研究工作。采用小波分解和去噪小波包分解方法,提取不同状态下随机核信号的时频能量特征,借助于统计学习理论的支持向量机(SVM)分类器原理进行训练和分类。研究结果表明:通过直接小波分解或去噪小波包分解,以获取核信号特征的方法是有效的;去噪小波包分解特征提取方式,较之直接小波分解特征提取方式更能反映中子裂变核系统的内部特征和规律;基于SVM核信号样本的分类,训练后的SVM分类器有着大于70%以上的正确率,且较好地克服了训练样本数较少的问题,验证了方法的可行性和有效性。     

An in-depth analysis of reflections in MMI couplers using optical low-coherence reflectometry: design optimization and performance evaluation

This paper describes a comprehensive report on the high potential of optical low-coherence reflectometry (OLCR) measurements to assist the design optimization and performance evaluation of symmetric MMI couplers. Using three sets of deep-ridge InGaAsP–InP couplers on InP and by performing OLCR measurements simultaneously in reflection and transmission modes, the nature and origin of all reflections in MMI have first been identified with respect to a deliberately chosen design parameter, namely, the coupler length. In addition, and in total agreement with the self-imaging principle and also the BPM simulations, the back reflections in combiner mode are shown to be prominent even in fully optimized devices. Finally, a simple design artifact has been proposed and demonstrated experimentally for the first time to suppress back reflections. Received: 16 May 2001 / Published online: 2 November 2001     

A wavelet-based method for multifractal image analysis. I. Methodology and test applications on isotropic and anisotropic random rough surfaces

We generalize the so-called wavelet transform modulus maxima (WTMM) method to multifractal image analysis. We show that the implementation of this method provides very efficient numerical techniques to characterize statistically the roughness fluctuations of fractal surfaces. We emphasize the wide range of potential applications of this wavelet-based image processing method in fundamental as well as applied sciences. This paper is the first one of a series of three articles. It is mainly devoted to the methodology and to test applications on random self-affine surfaces (e.g., isotropic fractional Brownian surfaces and anisotropic monofractal rough surfaces). Besides its ability to characterize point-wise regularity, the WTMM method is definitely a multiscale edge detection method which can be equally used for pattern recognition, detection of contours and image denoising. Paper II (N. Decoster, S.G. Roux, A. Arnéodo, to be published in Eur. Phys. J. B 15 (2000)) will be devoted to some applications of the WTMM method to synthetic multifractal rough surfaces. In paper III (S.G. Roux, A. Arnéodo, N. Decoster, to be published in Eur. Phys. J. 15 (2000)), we will report the results of a comparative experimental analysis of high-resolution satellite images of cloudy scenes. Received 8 July 1999     

激光法红外热像镜组中心偏测量与调校研究

论述了多镜片成像光学镜组中心偏的理论表征 ,以及自准反射旋转法测量中心偏的原理。设计了用于红外光学镜组的中心偏检测系统。系统包括用于 8～ 14 μm红外光学系统中心偏测量的CO2 激光 ;可调焦望远镜 ;采用TGS热释电热像仪与计算机配合的数据读出及处理系统 ;径向跳动≤ 1μm ,轴向晃动≤ 1″的高精密基准轴工作台。系统测量中心偏精度为 :角度≤ 2″ ,线度≤ 0 .0 2mm。给出了中心偏数据处理程序。系统也可用于在线装校 ,更换光源 (用He Ne激光代替CO2 激光 )系统可用于 3～ 5 μm红外光学系统的测量。进一步改进并利用激光的相干特性 ,系统可实现中心偏测量精度≤ 1μm。     

A novel method for detecting and counting overlapping tracks in SSNTD by image processing techniques

Overlapping object detection and counting is a challenge in image processing. A new method for detecting and counting overlapping circles is presented in this paper. This method is based on pattern recognition and feature extraction using “neighborhood values“ in an object image by implementation of image processing techniques. The junction points are detected by assignment of a value for each pixel in an image. As is shown, the neighborhood values for junction points are larger than the values for other points. This distinction of neighborhood values is the main feature which can be utilized to identify the junction points and to count the overlapping tracks. This method can be used for recognizing and counting charged particle tracks, blood cells and also cancer cells. The method is called “Track Counting based on Neighborhood Values” and is symbolized by “TCNV”.     

The method of simultaneous size and activity measurement of alpha emitting hot particles using multiple track analysis of solid state nuclear track detectors

Current work is concentrated upon the detection and analysis of hot particles from contaminated ground. Simultaneous measurement of parameters as activity and size of radioactive particle would have immense value for many applications in radiation protection and control of the environment. The algorithm and performance of multiple alpha track analysis is discussed.     

联合动静态图像分析技术研究鳄鱼血红细胞形态功能随pH值的变化

采用多维显微成像技术,结合有关动、静态图像分析方法,通过测定鳄鱼血红细胞在不同pH值下其形态参数(包括红细胞的接触面积、周长、长轴、短轴、伸长率和圆度)和反映细胞变形能力的频颤变化,揭示了鳄鱼血红细胞形态结构与有关生理功能随环境pH值的变化情况.结果表明,鳄鱼红细胞无论形态结构还是变形能力都比人体的红细胞更耐受酸性环境...