一种CSS-SIFT复合图像配准算法

针对SIFT算法的图像配准耗时长的问题,提出一种CSS-SIFT复合图像配准算法。CSS-SIFT算法首先使用CSS算法检测图像特征,然后,使用优化的SIFT算法生成并降维图像特征描述子,最后,使用基于欧式距离和曼哈顿距离的优化双向匹配算法对图像特征进行匹配。仿真实验条件是通过计算机中仿真软件进行仿真实验,统计图像特征数目、匹配数目、正确匹配数目、配准准确率、配准时间与配准时间下降率共6个指标数据,统计结果表明,CSS-SIFT算法在图像配准准确度方面与传统SIFT算法、传统SURF算法、Forstern-SIFT算法、Harris-SIFT算法、Trajkovic-SIFT算法相当,但在图像配准耗时方面分别降低了58.45%、10.68%、14.84%、16.21%与4.63%,为图像配准提供了一种解决方案。     

邻域多维度特征点结合相关熵的点云配准北大核心CSCD

针对传统点云配准中存在配准精度低、耗时长的问题,提出一种邻域多维度特征点结合相关熵模型的点云配准方法。首先根据邻域点的加权投影信息、表面曲率和法向量夹角提取特征点;其次用二值化的方向直方图描述子(B-SHOT)进行特征描述与匹配,然后利用刚性距离约束剔除误匹配,并通过随机采样一致性算法获取初始变换矩阵;在精配准阶段,以点到面的距离为准则双向搜索对应点,并通过多种几何特征约束剔除误匹配点对,最后迭代最大相关熵模型的目标误差函数完成精配准。实验结果表明,本文算法比迭代最近点算法(ICP)的配准精度提高了15%~97%、配准效率提高了约90%。     

一种基于改进SIFT算法的图像配准方法

给出一种改进的SIFT算法,并将该算法应用到图像配准中.首先,该改进算法结合Canny算子,去除影响匹配的边缘点.然后采用最近邻与次近邻之比来对96维描述子进行匹配.最后,采用随机抽样一致性(RANSAC)方法消除误匹配.实验结果表明,与原SIFT算法相比,该算法能够有效提高图像配准确度,并减少了10%左右的运算时间.     

融入曲率尺度空间算法的图像配准方法

为了满足图像配准对于实时性的要求,提出融入曲率尺度空间算法的图像配准方法。首先使用曲率尺度空间算法提取图像角点特征,然后使用改进的加速稳健特征算法生成64维角点特征描述子向量并将描述子向量降维到24维,最后使用改进的相似性距离算法和随机采样一致性算法进行匹配。仿真实验一表明:在图像配准准确度方面与传统尺度不变特征变换算法、传统加速稳健特征算法及其他改进的图像配准方法相当,但在图像配准实时性方面具有一定的优势,仿真实验二通过立体匹配库验证了该方法具有普遍有效性。     

SIFT与形状上下文结合的异源图像匹配算法

针对红外图像和可见光图像灰度差异大、匹配困难的问题,提出了一种基于改进的尺度不变特征变换和形状上下文描述的局部多特征匹配算法。首先通过高斯差分检测算法分别提取两幅图像的特征点;针对特征点梯度方向存在反转现象,结合梯度镜像方法对特征点统计特征点邻域梯度方向信息;然后引入图像边缘特征生成形状上下文描述子,与梯度方向描述子级联成联合描述子;最后采用欧氏距离和卡方距离加权的联合距离和最近邻算法对特征点进行匹配。实验结果证明,在红外图像和可见光图像匹配中,该算法相比原始SIFT算法能有效减少误匹配特征点对,达到较高的匹配精度。     

红外与可见光图像自相似性特征的描述与匹配

针对红外与可见光图像匹配的难题,提出了一种基于自相似性的异源图像点特征匹配算法。首先对红外与可见光图像进行小邻域平方和计算;再通过构造高斯金字塔,运用FAST-9进行角点检测,使得检测的特征点具有尺度属性;然后,统计特征点邻域的特征信息以确定特征点的主方向;再求取在相应尺度下特征点邻域的相关平面,对相关平面进行区域划分,提取每个区域相关平面的极值以构造100维的自相似性描述子,并对描述子进行归一化处理;而后,剔除不良特征描述子;最后采用最近邻匹配算法进行特征匹配。实验结果表明,提出的算法能够实现红外与可见光图像在视角、旋转、尺度变换下的有效匹配;在保证运算速度的前提下,提出的算法较SIFT算法在正确匹配率方面有明显提高。     

一种改进的基于不变描述子的图像自动配准方法

本文提出了一种改进的基于不变描述子的图像自动配准方法来处理具有全局仿射变换的图像配准问题.该方法主要分为三步:首先,利用Mean-shift算法和区域标记算法分别从参考图像和待配准图像中提取区域特征作为配准基元,采用7个仿射不变矩作为不变描述子;其次,通过组合仿射不变矩的最小距离准则和行、列匹配概率系数算法获得一个候选匹配区域特征集,运用穷举策略从中得到三个最好的匹配区域特征,利用它们的重心点坐标计算仿射变换模型参数的初始值;最后,根据空间一致性检测获得所有正确的匹配区域特征,利用它们的重心点坐标和最小二乘算法估计最优的仿射变换模型参数.仿真和实际图像数据的配准实验和对比实验结果表明本文方法具有较高的可靠性和配准精度.     

基于椭圆傅里叶描述子的遥感图像配准算法

传统的基于点特征的图像配准算法在遥感图像配 准时提取的特征点数量大、分布密,易产生误匹配,导致特 征匹配的效率和精度低。为此,本文利用椭圆傅里叶描述子(EFD)能较好保留 形状信息的特点,提出了一种基于EFD的 图像配准算法,根据匹配的边界对预估变换参数,给出特征搜索范围,从而有效地提 高特征搜索的效率。实 验结果表明,所提出算法能有效抑制误匹配的产生,提升特征匹配的效率,尤其是对于纹理 丰富的大尺寸图像,提 升效果更加明显,验证了本文算法对遥感图像配准的适用性。     

基于视觉模糊的LBP鲁棒特征提取与匹配

目的针对目前模糊图像特征提取与匹配方面, 存在特征提取困难、匹配率低、抗噪以及抗尺度变 化能力弱的缺陷。方法提出一种基于SIFT算法与改进的中心对称局部二值模式相结合的精准 、特征识别 率高的匹配算法。首先采用SIFT进行特征的提取,生成多维的描述子,其次采用本文改进的 中心对称局 部二值模式对高维特征描述子进行降维处理,并采用局部特征区域对降维后的描述子进行特 征检测,并生 成纹理特征图像以及信息分布直方图,对特征区域的特征点进行信息量统计,并设置检测阈 值。提取符合 特征信息要求的特征点,并依据Hausdorff距离算法实现图像粗匹配,最后采用RANSAC算法 进行误差匹 配的剔除来改善匹配的精度和鲁棒性。结果测试结果表明,本文所建议的算法是有效的,它 不仅具有良 好的模糊图像分辨能力和抗尺度变化特性,而且具有较强的噪声抑制能力和抗光照变化能力 。结论本文 提出的基于视觉模糊的鲁棒特征匹配算法,不仅考虑到传统特征匹配算法的优缺点,也提出 了算法改进的 新思路,而且较SIFT算法以及LBP算法稳定性和准确度有了明显的提高。     

一种基于图像区域分块的SIFT快速配准方法

针对传统尺度不变特征变换(SIFT)算法在特征提取与描述时计算量大、实时性差的问题,提出一种基于区域分块的SIFT的快速配准方法。首先,将匹配图像和待匹配图像分割成若干均匀的子图,通过计算每个子图的信息熵值与设定阈值比较来确定局部子图的特征类型;对筛选出来的特征区域的子图进行特征提取和生成PCA-SIFT描述子,对筛选出来的平坦区域直接跳过,不进行检测。实验结果表明:提出的方法在保证配准精度90%以上的情况下,计算时间减少了15%~25%左右,提高了图像配准的速度。     

Curved crystal spectrometer for the measurement of X-ray lines from laser-produced plasmas

In order to diagnose the laser-produced plasmas, a focusing curved crystal spectrometer has been developed for measuring the X-ray lines radiated from a laser-produced plasmas. The design is based on the fact that the ray emitted from a source located at one focus of an ellipse will converge on the other focus by the reflection of the elliptical surface. The focal length and the eccentricity of the ellipse are 1350 mm and 0.9586, respectively. The spectrometer can be used to measure the X- ray lines in the wavelength range of 0.2-0.37 nm, and a LiF crystal （200） （2d = 0.4027 nm） is used as dispersive element covering Bragg angle from 30° to 67.5°. The spectrometer was tested on Shengnang- Ⅱ which can deliver laser energy of 60-80 J/pulse and the laser wavelength is 0.35 μm. Photographs of spectra including the 1 s2p ^1P1-1s^2 ^1S0 resonance line（w）, the 1s2p ^3P2-1s^2 1S0 magnetic quadrupole line（x）, the 1s2p ^3P1-1 s^2 ^1S0 intercombination lines（y）, the 1 s2p ^3S~1-1 s^2 ^1S0 forbidden line（z） in helium-like Ti Ⅹ Ⅺ and the 1 s2s2p ^2P3/2-1 s622s ^2S1/2 line（q） in lithium-like Ti Ⅹ Ⅹhave been recorded with a X-ray CCD camera. The experimental result shows that the wavelength resolution（λ/△ 2） is above 1000 and the elliptical crystal spectrometer is suitable for X-ray spectroscopy.     

Preparation and Characterization of TaN ALD Precursors

High purity organic-tantalum precursors for thin film ALD TaN were synthesized and characterized.Vapor pressure and thermal stability of these precursors were studied.From the vapor pressure analysis,it was found that TBTEMT has a higher vapor pressure than any other published liquid TaN precursor,including TBTDET,TAITMATA,and IPTDET.Thermal stability of the alkyl groups on the precursors was investigated using a 1H NMR technique.The results indicated that the tertbutylimino group is the most stable group on TBTDET and TBTEMT as compared to the dialkylamido groups.Thermal stability of TaN precursors decreased in the following order:TBTDET ＞ PDMAT ＞ TBTEMT.In conclusion,precursor vapor pressure and thermal stability were tuned by making slight variations in the ligand sphere around the metal center.     

Electronic Structure of Semiconductor Nanocrystals

This paper reviews our recent development of the use of the large-scale pseudopotential method to calculate the electronic structure of semiconductor nanocrystals, such as quantum dots and wires, which often contain tens of thousands of atoms. The calculated size-dependent exciton energies and absorption spectra of quantum dots and wires are in good agreement with experiments. We show that the electronic structure of a nanocrystal can be tuned not only by its size,but also by its shape. Finally,we show that defect properties in quantum dots can be significantly different from those in bulk semiconductors.     

Critical Stage Rule-Based Real Time Dispatch（RTD）System in Highly-Mixed-Products （HMP） FAB

An improving utilization and efficiency of critical equipments in semiconductor wafer fabrication facilities are concerned. Semiconductor manufacturing FAB is one of the most complicated and cost sensitive environments. A good dispatching tool will make big difference in equipment utilization and FAB output as a whole. The equipment in this paper is In-Line DUV Scanner. There are many factors impacting utilization and output on this equipment group. In HMP environment one of the issues is changing of reticule in this area and idle counts due to load unbalance between equipments. Here we'll introduce a rule-based RTD system which aiming at decreasing the number of recipe change and idle counts among a group of scanner equipment in a high-mixed-products FAB.     

GaAsSb/InAlAs PA DHBTs Grown by Production MBE

The epi material growth of GaAsSb based DHBTs with InAlAs emitters are investigated using a 4 × 100mm multi-wafer production Riber 49 MBE reactor fully equipped with real-time in-situ sensors including an absorption band edge spectroscope and an optical-based flux monitor. The state-of-the-art hole mobilities are obtained from 100nm thick carbon-doped GaAsSb. A Sb composition variation of less than ± 0.1 atomic percent across a 4 × 100mm platen configuration has been achieved. The large area InAlAs/GaAsSb/InP DHBT device demonstrates excellent DC characteristics,such as BVCEO＞6V and a DC current gain of 45 at 1kA/cm2 for an emitter size of 50μm × 50μm. The devices have a 40nm thick GaAsSb base with p-doping of 4. 5 × 1019cm-3 . Devices with an emitter size of 4μm × 30μm have a current gain variation less than 2% across the fully processed 100mm wafer. ft and fmax are over 50GHz,with a power efficiency of 50% ,which are comparable to standard power GaAs HBT results. These results demonstrate the potential application of GaAsSb/InP DHBT for power amplifiers and the feasibility of multi-wafer MBE for mass production of GaAsSb-based HBTs.     

Influence of polarization extinction ratio on distributed polarization coupling detection

Distributed polarization coupling in polarization-maintaining fibers can be detected by using a white light Michelson interferometer. This technique usually requires that only one polarization mode is excited. However, in practical measurement, the injection polarization direction could not be exactly aligned to one of the principal axes of the PMF, so the influence of the polarization extinction ratio should be considered. Based on the polarization coupling theory, the influence of the incident polarization extinction on the measurement result is evaluated and analyzed, and a method for distributed polarization coupling detection is developed when both two orthogonal eigenmodes are excited.     

Noise character analysis and the restraint of self-pulsation laser diodes

We calculate the Langevin noise sources of self-pulsation laser diodes, analyze the effects of active region noise and saturable-absorption region noise on the power fluctuation as well as period fluctuation, and propose a novel method to restrain the noise effects. A visible SIMULINK model is established to simulate the system, The results indicate that the effects of noise in absorption region can be ignored; that with the increase of DC injecting current, the noise effects enhance power jitter, and nevertheless, the period jitter is decreased; and that with external sinusoidal current modulating the self-pulsation laser diode, the noise-induced power jitter and period jitter can be suppressed greatly. This work is valuable for clock recovery in all-optical network.     

High-quality single-crystal CdSe nanoribbons and their optical properties

Large-scale synthesis of single-crystal CdSe nanoribbons is achieved by a modified thermal evaporation method, in which two-step-thermal-evaporation is used to control CdSe sources＇ evaporation. The synthesized CdSe nanoribbons are usually several micrometers in width, 50 nm in thickness, and tens to several hundred micrometers in length. Studies have shown that high-quality CdSe nanoribbons with regular shapes can be obtained by this method. Room-temperature photolumines-cence indicates that the lasing emission at 710 nm has been observed under optical pumping （266 nm） at power densities of 25-153 kW/cm^2. The full width half maximum （FWHM） of the lasing mode is 0.67 nm     

Propagation of hermite-cosh-gaussian beams passing through ABCD optical system with an annular aperture

By using the expansion of the aperture function into a finte sum of complex Gaussian functions, the corresponding analytical expressions of Hermite-cosh-Gaussian beams passing through annular apertured paraxially and symmetrically optical systems written in terms of ABCD matrix were derived, and they could reduce to the cases with squared aperture. In a similar way, the corresponding analytical expressions of cosh-Gaussian beams through annular apertured ABCD matrix were also given. The method could save more calculation time than that by using the diffraction integral formula directly.     

中国建立EB级存储实验室,致力云计算应用(英文)

正With the support of 863 programs,Sugon Information Industry Co.,Ltd.,set up a dawning EB-class storage laboratory to address massive data storage requirements and largescale cloud computing demonstration applications.The Dawning EB-class cloud storage system adopts advanced fault-tolerant architecture,efficient data fault-tolerant algorithms with user authentication and data encryption policies to deal with the"lost""wrong"and"stolen"problems of data for ensuring the reliability and safety of the EB-class storage system in the public network application environments.The Dawning EB-class Storage Laboratory taking advan-