基于红外热图像的标准几何体重构方法的研究

在红外图像特征提取的基础上，提出了一种基于单幅红外图像自动识别并重构标准几何体的方法，即采用红外目标图像上关键点的几何特性对红外目标进行自动分类；利用空间直角变换以获得目标的关键参数；最后实现了红外目标图像的标准几何体的三维模型重构，为复杂红外目标的自动重构打下基础。     

基于红外图像的遮挡标准几何体重构方法的研究

在基于单幅红外图像自动识别并重构标准几何体的方法基础上,利用正侧两幅红外图像对带有遮挡的标准几何体的组合进行自动识别和分类,提取图像的清晰边缘后通过提取遮挡几何体未被遮挡的对称区域来提取被遮挡几何体几何特征;利用空间直角变换获得尺寸参数,最后应用三维重构模型实现多目标有遮挡的红外图像的几何体系统的三维模型重构,为复杂的红外目标的自动重构打下基础。     

基于激光点云数据的三维运动图像重构技术北大核心CSCD

为了解决三维运动图重构时存在的重构测量距离与实际距离误差大、激光点云数据数量多和重构图像清晰度对比低的问题,提出了基于激光点云数据的三维运动图像重构技术,通过配准多帧激光点云数据,从中获取激光点云数据集,再采用平面拟合方法对激光点云数据集实行去噪处理,最后利用曲面重构法完成对曲面模型的拟合,实现三维运动图像重构。实验结果表明,通过对三维运动图像重构进行测量距离与实际距离的对比、激光点云数据数量的对比和测量图像与实际图像清晰度的对比测试,验证了三维运动图像重构技术的实用性高。     

运动视觉误差分析的模型设计与实现

针对运动目标模型三维建模中,视觉误差导致建模的准确性不好的问题,提出一种基于运动视觉误差补偿的三维模型设计方法。采用全息投影方法进行三维运动模型图形采集,结合边缘像素特征提取方法进行三维模型的体绘制,根据运动视觉误差补偿方法构建图像重构的三维数据场,进行运动模型的边缘轮廓特征提取和Harris角点检测,实现运动模型的三维重建和视景仿真重构。仿真结果表明,采用该方法进行运动模型重建,输出三维模型的噪点较小,轮廓特征配准精度较高,运动图像识别的视觉误差收敛到零,提高成像质量。     

基于Harris角点检测与聚类算法的空间自旋目标干涉三维成像

对空间微动目标进行干涉式成像,需要剔除微动曲线交叉位置的干涉相位值,以确保成像的准确性。针对空间自旋目标窄带雷达干涉三维成像问题,首先利用Harris角点检测与聚类算法对回波时频图像中的角点进行搜索与分类,准确找到散射点微动曲线的交叉位置,然后对交叉位置处的干涉相位信息予以剔除,再利用各散射点的干涉相位信息重构出了两基线方向上的坐标曲线,最后根据目标在空间中的圆轨迹与两基线平面内的椭圆轨迹之间的几何关系,实现对空间自旋目标的干涉三维成像。仿真结果验证了所提方法的有效性。      

基于SUSAN原理的黄河模型角点检测

分析了SUSAN算法进行角点检测的原理和有效性,在此基础上提出了一种采用改进了的SUSAN算法来提取黄河模型图像的角点特征。利用自适应的选取灰度差阈值的方法;再采用利用设定几何阈值的上下限方法,实现了黄河模型角点的自动识别和检测。实验表明,该方法提取的角点抗噪性能好,清晰真实,细致,定位精确。为下一步立体匹配和三维重构打下了基础。     

基于偏振双目视觉的无纹理高反光目标三维重构

对于表面光滑、纹理单一甚至缺失、高反光的目标,传统的三维重构方法由于对纹理以及反光特性的依赖会使得重构表面出现大面积的的数据空洞.而基于偏振的三维重构方法不依赖于物体表面的纹理信息,同时偏振成像能够在一定程度上抑制耀光,能够有效解决传统三维重构方法存在的问题.但是,基于偏振视觉的三维重构方法得到的是像素坐标系下的深度信息,因此提出了偏振双目视觉三维重构方法,以由双目立体视觉获得的少量特征点的世界三维坐标为"桥梁",利用双目立体标定得到的相机参数,将偏振得到的图像像素坐标系下的点云数据转化为世界坐标系下的绝对数据.     

云计算环境下的三维图像数据重构方法

针对传统三维虚拟技术进行三维图像数据重构时存在重构精度低、清晰度不高的问题,提出云计算环境下的三维图像数据重构方法。构建了Hadoop结构的云计算环境,其由Map Reduce编程应用、HDFS分布式计算应用、Hbase开源数据库以及多项Apache服务器软件构成。选取体素作为三维图像数据重构的基本单元,采用各向异性分散过滤法在Hadoop结构中腐蚀体素,达到图像去噪和消除体素不稳定形态的目的。采用一种跳跃性的三维空间索引方法进行三维图像数据重构,减少对无用体素索引的过程,提高重构效率。实验结果表明,所提方法的重构效果好、清晰度高。     

基于大数据可视化激光测距城市空间三维图像重构

针对当前三维图像重构效率差,重构结果遍历覆盖度低等问题,提出基于大数据可视化激光测距城市空间三维图像重构方法。利用激光测距仪采集大量城市空间三维点云元数据,对元数据实施序列化处理获取城市空间相关大数据。基于获取的数据进行可视化分析,点云数据中包含激光采样点数值范围,可构建城市空间数字表面模型;利用该模型获取城市地面高度均值,通过曲面拟合获取城市空间数字地面模型;根据上述两个模型划分城市空间地面建筑物,获取城市空间内建筑物三维信息。通过三角形网格法将三维点信息转换为三维面信息,实现城市空间三维图像重构。测试结果显示,所提方法三维图像重构加速比达到5.53,输出图像遍历覆盖最高可达98.83%,说明该方法可实现最初研究目的。     

基于双目视觉的目标完整点云获取方法

快速获取复杂形状目标的完整三维点云,重构目标的三维模型是目前智能检测和机器人识别与定位的关键技术和难点。基于立体视觉,提出一种图像预处理和优化半全局立体匹配过程的方法。该方法设计了图像预处理算法,与半全局立体匹配和点云配准算法配合使用,获取复杂形状目标完整的三维点云。搭建了硬件实验平台和旋转工作台,获取多角度下目标的左右图像对,在此平台上开发了一套基于双目视觉的点云获取系统,并以复杂形状的齿轮为实验对象对该系统进行测试。测试结果表明,该方法生成的物体三维点云效果良好,为目标三维重构提供方法和理论,实用性较强,并且系统运行速度快,算法处理过程可行。     

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.     

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.     

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.     

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.     

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.     

Call for Papers

正Communications—VLSI Researches and industries of telecommunications have been growing rapidly in the last 20 years and will keep their high growing pace in the next decade.The involved researches and developments cover mobile communications,highway and last-mile broadband communication,domain specific communications,and emerging D2D M2M communications.Radio communication steps into its