基于轮廓特征点最大互信息的多模态医学图像配准

提出了一种基于轮廓特征点最大互信息的多模态医学图像配准方法,并将粒子群优化算法(PSO)和Powell算法相结合以一种组合的全局优化算法(PPSO)来求取最优配准变换参数.实验结果表明,该方法具有配准精度高、速度快、鲁棒性强等特点,是一种有效地全自动配准方法.     

融合特征点提取的三维点云配准方法

为了改进传统迭代最近点云配准方法配准精度低,需要较好的初始输入变换矩阵等问题,提出一种基于分块思想结合点云平面拟合提取特征点的改进型点云配准方法。首先,对点云进行分块,结合随机采样一致性定理进行块状点云的平面拟合和特征点提取。其次,采用快速点对直方图来描述点云特征,利用采样一致性配准算法进行初始配准,为精配准奠定良好的基础。精配准通过K-D树改进加速迭代最近点算法,实现点云的整体配准。试验结果表明,所提出的点云配准方法在两种测试集上相较于传统最近迭代点方法,在配准精度上提升89.23%和31.45%,相较于其他点云配准方法,提出的方法也有一定的优势。     

基于SIFT特征点结合ICP的点云配准方法

在点云配准过程中,针对迭代最近点(ICP)算法对点云初始位置依赖性强且迭代速度慢的问题,提出一种基于尺度不变特征变换(SIFT)特征点结合ICP的点云配准方法.首先利用SIFT算法提取待配准点云和目标点云的特征点;接着计算出特征点的快速点特征直方图(FPFH)特征;然后依据该特征使用采样一致性初始配准(SAC-IA)算...     

基于超体素与几何特征融合的点云配准优化

针对点云配准过程中点云数据冗余、易出现误匹配点对和配准精度低的问题,提出了一种融合超体素及几何特征的点云配准方法。首先使用超体素与法向量信息相结合的方法提取特征点;其次,在粗配准中,通过使用快速特征点直方图(Fast Point Feature Histograms,FPFH)进行特征描述,采用双向最近邻比获取初始特征点对应关系,基于法向量夹角策略和随机采样一致性(Random Sample Consensus,RANSAC)算法进行对应关系的优化,获取良好的初始位姿;最后,在精配准中,基于初始位姿与改进的迭代最近点算法(Iterative Closest Point,ICP)算法完成点云配准。通过在斯坦福数据集中进行配准实验,验证了所提算法具有更好的鲁棒性,能高效且精准的完成点云配准。     

基于改进ICP的复杂机械零件测量点云配准方法

点云配准是基于机器视觉进行复杂机械零件三维非接触精密测量的关键环节。针对传统迭代最近点(iterative closest point, ICP)算法对初始位置依赖性强,迭代收敛速度慢,错误对应点对多,难以满足大批量复杂机械零件测量点云配准效率和精度要求的问题,提出了一种基于ISS-FPFH(intrinsic shape signature-fast point feature histogram)特征结合改进ICP的复杂机械零件测量点云配准方法。为了减少点云配准数量,并保留点云表面原来的细微特征,提出了基于重心邻近点的体素滤波器对点云进行下采样预处理。为解决传统ICP算法因合适初始位置难以确定而导致多视角测量点云配准失败的问题,采用了基于ISS-FPFH特征的采样一致性初始配准(sample consensus intial alignment, SAC-IA)算法进行粗配准。为解决传统ICP算法迭代收敛速度慢、错误对应点对多的问题,提出结合法向量夹角约束的点到平面ICP算法进行精配准。以斯坦福大学的bunny点云模型为对象,验证了本文提出方法对噪声点云的鲁棒性。以常见的复杂机械零...     

自适应局部邻域特征点提取和匹配的点云配准

点云配准是三维重建的关键技术之一。针对点云匹配中迭代最近点算法(ICP)速率低、对初始位置要求高的问题,提出了一种基于自适应局部邻域特征点提取和匹配的点云配准方法。首先根据局部表面变化因子与平均变化因子的大小关系,自适应地提取特征点;其次利用快速点特征直方图（FPFH）综合描述每个特征点的局部信息,结合随机抽样一致性（RANSAC）算法实现粗配准;最后根据得到的初始变换矩阵和基于特征点的ICP算法实现精配准。对斯坦福数据集、含噪声的点云以及场景点云进行配准实验,实验结果表明:所提出的特征点提取算法能高效地提取点云的特征;相比于其他特征点检测方法,所提方法在粗配准中的配准精度和配准速度更高,且抗噪性能更好;与ICP算法相比,基于文中特征点的ICP算法在斯坦福数据集和场景点云中的配准速度提升了约10倍,在含噪声的点云中,能根据所提取的特征点高效地进行配准。该研究为提高三维重建和目标识别的匹配效率提供了一种高效的方法。     

实现激光点云高效配准的ICP优化及性能验证

激光点云常规匹配算法是迭代最近点(Iterative Closest Point, ICP)算法,但其收敛速度慢、鲁棒性差,因此,提出一种融合多种优化算法的激光点云高效ICP配准方法。首先对点云体素滤波降采样,通过ISS算子提取关键点,采用快速点特征直方图(Fast Point Feature Histograms, FPFH)提取关键点特征,嵌入多核多线程并行处理模式 (OpenMP)提高特征提取速度;然后基于提取的FPFH特征,使用采样一致性初始配准算法(Sample Consensus Initial Alignment, SAC-IA)进行相似特征点粗配准,获取点云集间的初始旋转平移变换矩阵;最后采用ICP算法进行精配准,同时采用最优节点优先(Best Bin First, BBF)优化K-D tree近邻搜索法来加速对应关系点对的搜索,并设定动态阈值消除错误对应点对,提高配准快速性和准确性。对两个实例的配准点云进行了实验验证,结果表明,提出的优化配准算法具有明显速度优势和精度优势。     

基于快速点特征直方图的三维点云配准算法

三维点云配准算法是三维场景模型重建的重要研究部分。针对传统迭代最近点算法(ICP)对点云进行配准时容易陷入局部最优的问题,本文研究了基于局部特征点改进的ICP算法。文章分析了点特征直方图(PFH)和快速点特征直方图(FPFH)两种局部特征点,得出了FPFH具有比PFH更低的时间复杂度的结论,因此通过FPFH特征描述子对两片初始点云进行粗配准,使其具有较好的初始位姿,最后用经典的ICP算法进行精配准。实验结果表明,基于FPFH特征点改进后的ICP算法能提供较好的点云初始位姿,一定程度上避免了配准时陷入局部最优的问题,比传统ICP算法具有更好的配准效果。     

基于轮廓曲线特征的破碎物体重组算法

由于大多数断裂面拼接算法主要适用于断裂面粗糙且特征丰富的碎片,针对部分破碎物体碎片断裂面特征稀少难以提取的问题,提出一种既适用于断裂面粗糙又适用于断裂面光滑的基于轮廓曲线特征的破碎物体重组算法。首先利用区域生长算法和改进的曲面融合算法分割出破碎物体碎片断裂面。然后,利用边界提取算法得到断裂面的边缘轮廓曲线,将经过体素滤波处理过后的边缘轮廓曲线作为配准的基础。最后,采用4PCS算法和迭代最近点算法对处理过的碎片边缘轮廓曲线进行粗配准和精细配准,并将旋转平移矩阵应用到原始碎片中得到拼接结果。结果表明,所提出的算法能够适用于断裂面特征丰富和特征较为稀少的破碎物体重组,有效解决了基于断裂面表面特征的算法无法拼接断裂面光滑碎片的问题。     

一种多模式融合的激光点云配准算法

针对经典迭代最邻近点(iterative closest point,ICP)算法在三维激光点云配准领域内,存在收敛速度慢、配准误差大、配准效率低的问题,提出了一种基于法向量夹角特征和边界旋转角相融合的改进ICP算法。利用点云区域层划分将点云分成若干独立单元方格,搜寻方格的法向量夹角特征关键点,结合点面曲率对应关系形成初始匹配点对,随后引入距离约束函数,估算边界旋转角和相关动态迭代系数,自动优化刚性变换参数。实验结果表明,与传统ICP算法相比,改进后的算法配准误差降至0.3%以下,配准时间减少50%以上,有效提升点云配准效率。     

Resolution Enhancement Technology:Integrated Process Solutions using OPC

DUV lithography, using the 248 nm wavelength, is a viable manufacturing option for devices with features at 130 nm and less. Given the low kl value of the lithography, integrated process development is a necessary method for achieving acceptable process latitude. The application of assist features for rule based OPC requires the simultaneous optimization of the mask, illumination optics and the resist.Described in this paper are the details involved in optimizing each of these aspects for line and space imaging.A reference pitch is first chosen to determine how the optics will be set. The ideal sigma setting is determined by a simple geometrically derived expression. The inner and outer machine settings are determined, in turn,with the simulation of a figure of merit. The maximum value of the response surface of this FOM occurs at the optimal sigma settings. Experimental confirmation of this is shown in the paper.Assist features are used to modify the aerial image of the more isolated images on the mask. The effect that the diffraction of the scattering bars (SBs) has on the image intensity distribution is explained. Rules for determining the size and placement of SBs are also given.Resist is optimized for use with off-axis illumination and assist features. A general explanation of the material' s effect is discussed along with the affect on the through-pitch bias. The paper culminates with the showing of the lithographic results from the fully optimized system.     

Cost-effective test solutions for smart card and other integrated flash applications

From its emergence in the late 1980s as a lower cost alternative to early EEPROM technologies, flash memory has evolved to higher densities and speedsand rapidly growing acceptance in mobile applications.In the process, flash memory devices have placed increased test requirements on manufacturers. Today, as flash device test grows in importance in China, manufacturers face growing pressure for reduced cost-oftest, increased throughput and greater return on investment for test equipment. At the same time, the move to integrated flash packages for contactless smart card applications adds a significant further challenge to manufacturers seeking rapid, low-cost test.     

Theoretical analysis of the relationship between the Brillouin gain coefficient and the strain in the optical-fiber sensors

The relation between the power of the Brillouin signal and the strain is one of the bases of the distributed fiber sensors of temperature and strain. The coefficient of the Bfillouin gain can be changed by the temperature and the strain that will affect the power of the Brillouin scattering. The relation between the change of the Brillouin gain coefficient and the strain is thought to be linear by many researchers. However, it is not always linear based on the theoretical analysis and numerical simulation. Therefore, errors will be caused if the relation between the change of the Brillouin gain coefficient and the strain is regarded as to be linear approximately for measuring the temperature and the strain. For this reason, the influence of the parameters on the Brillouin gain coefficient is proposed through theoretical analysis and numerical simulation.     

An improved parallel thinning algorithm with two subiterations

The parallel thinning algorithm with two subiterations is improved in this paper. By analyzing the notions of connected components and passes, a conclusion is drawn that the number of passes and the number of eight-connected components are equal. Then the expression of the number of eight-connected components is obtained which replaces the old one in the algorithm. And a reserving condition is proposed by experiments, which alleviates the excess deletion where a diagonal line and a beeline intersect. The experimental results demonstrate that the thinned curve is almost located in the middle of the original curve connectivelv with single pixel width and the processing speed is high.     

Novel fiber-optical interferometer with miniaturized probe for in-hole measurements

Today, micro-system technology and the development of new MEMS （Micro-Electro-Mechanical Systems） are emerging rapidly. In order for this development to become a success in the long run, measurement systems have to ensure product quality. Most often, MEMS have to be tested by means of functionality or destructive tests. One reason for this is that there are no suitable systems or sensing probes available which can be used for the measurement of quasi inaccessible features like small holes or cavities. We present a measurement system that could be used for these kinds of measurements. The system combines a fiber optical, miniaturized sensing probe with low-coherence interferometry, so that absolute distance measurements with nanometer accuracy are possible.     

Study of waveguide coupling efficiency in hybrid silicon lasers

This paper presents a new method to increase the waveguide coupling efficiency in hybrid silicon lasers. We find that the propagation constant of the InGaAsP emitting layer can be equal to that of the Si resonant layer through improving the design size of the InP waveguide. The coupling power achieves 42% of the total power in the hybrid lasers when the thickness of the bonding layer is 100 nm. Our result is very close to 50% of the total power reported by Intel when the thickness of the thin bonding layer is less than 5 nm. Therefore, our invariable coupling power technique is simpler than Intel＇s.     

Teleportation of an arbitrary unknown N-qubit entangled state under the controlling of M controllers

A new quantum protocol to teleport an arbitrary unknown N-qubit entangled state from a sender to a fixed receiver under M controllers(M < N) is proposed. The quantum resources required are M non-maximally entangled Greenberger-Home-Zeilinger (GHZ) state and N-M non-maximally entangled Einstein-Podolsky-Rosen (EPR) pairs. The sender performs N generalized Bell-state measurements on the 2N particles. Controllers take M single-particle measurement along x-axis, and the receiver needs to introduce one auxiliary two-level particle to extract quantum information probabilistically with the fidelity unit if controllers cooperate with it.     

Diode-end-pumped Nd:YVO4/LBO lasers with 4.2W continuous-wave output at 457 nm

A continuous-wave (CW) 457 nm blue laser operating at the power of 4.2 W is demonstrated by using a fiber coupled laser diode module pumped Nd: YVO4 and using LBO as the intra-cavity SHG crystal With the optimization of laser cavity and crystal parameters, the laser operates at a very high efficiency. When the pumping power is about 31 W, the output at 457nm reaches 4.2 W, and the optical to optical conversion efficiency is about 13.5% accordingly. The stability of the out putpower is better than 1.2% for 8 h continuously working.     

A rigorous proof of MIMO channel capacity’s increase with antenna number

It is well known that adding more antennas at the transmitter or at the receiver may offer larger channel capacity in the multiple-input multiple-output（MIMO） communication systems. In this letter, a simple proof is presented for the fact that the channel capacity increases with an increase in the number of receiving antennas. The proof is based on the famous capacity formula of Foschini and Gans with matrix theory.     

Call for Papers

正Wireless Body-area Networks The last decade has witnessed the convergence of three giant worlds:electronics,computer science and telecommunications.The next decade should follow this convergence in most of our activities with the generalization of sensor networks.In particular with the progress in medicine,people live longer and the aging of population will push the development of wireless personal networks