复杂背景中维-汉混排字符串的分割技术研究

提出了一种基于混合高斯模型拟合选取阈值和区域生长的图像分割方法:首先利用笔画方向算子对文字笔画进行抽样,再利用混合高斯模型拟合其灰度直方图,确定样本的最佳分割阈值,最后利用样本的标准差作为生长规则的判断依据分割文字。该算法计算量小,实时性和分割精度均有一定优势,在提取目标的同时,残留背景像素极少,使下一步的目标识别更为简单。     

铁路视频监控中运动目标检测算法研究

运动目标的正确检测影响着运动目标能否被正确跟踪与分类,因此成为视频监控系统研究中的一项重要课题。文中对运动目标检测算法进行研究,实现对铁路沿线前方目标的有效识别,针对得到的视频序列,通过混合高斯模型进行背景建模,并与混合差分算法结合实现前景的提取与检测。通过与混合差法相比较,其仿真结果表明,该算法具有一定的可行性。     

基于高斯混合背景模型的运动目标检测技术研究

在运动目标检测技术中,使用传统的高斯混合背景模型所得到的检测结果并不能完美地获取运动目标的轮廓信息,而图像中像素的梯度信息,刚好就是反映了各物体的轮廓和边界,并且相对于颜色信息而言,梯度信息对于噪声并不敏感。为此,该文对传统的高斯混合背景模型进行了改进,提出基于梯度时空信息的高斯混合背景模型,证明了改进的算法确实能够取...     

基于改进高斯混合模型的运动图像目标检测算法

运动图像目标检测指的是从序列图像中将变化的目标从背景中分离出来,高斯混合模型可以对视频序列图像的前景和背景进行分类,再利用背景减除实现运动目标的检测。提出一种基于改进高斯混合模型的优化背景建模方法,该方法首先利用3×3模板对序列图像帧中的像素进行类似卷积的均值计算,然后利用相邻均值的差提取均差因子自适应更新图像的均值。在此基础上,设计了自适应学习率和学习速率,利用改进高斯混合模型实现序列图像的背景建模。改进模型不仅能有效减少数据计算量,同时可以降低在相似区域像素计算的时长,大大加快背景建模速度。实验结果表明,改进模型在目标检测、算法执行速率等性能指标上都有更好的表现,能满足实时检测要求。     

交通视频的移动目标检测算法研究

对视频序列的目标进行识别和跟踪监控是计算机视觉领域的关键技术。依据图像处理和目标检测研究方向的热点算法,将帧间差分与混合高斯背景模型融合法应用于交通视频移动车辆的目标检测分析中。该算法通过背景差分求出光照影响的动态阈值范围,若光照检测阈值小于该动态阈值,选择混合高斯背景模型法,大于该动态阈值则选取帧间差分法。再通过开运算、闭运算、连通域计算,以及区域的凸包形态学运算即可准确描述目标。实验结果表明,该融合算法消除了鬼影现象,在光照环境改善的情况下可以有效应用于交通视频中移动车辆的目标检测。     

基于HOG特征的织物瑕疵检测算法

传统织物瑕疵检测依赖人工,成本高且效率低.提出基于机器视觉和图像处理算法的织物瑕疵检测方法,采用方向梯度直方图描述织物纹理特征,通过计算局部区域的方向梯度直方图特征与无瑕疵织物图像特征的相似性来识别瑕疵,在织物图像数据集上的待测结果表明,此算法能够有效地提取出织物的瑕疵.     

复杂背景下红外人体目标检测算法研究

红外图像信噪比和对比度较低、缺乏颜色纹理信息、目标周围有光晕效应、边缘模糊,这些缺点对红外图像中人体目标检测提出了挑战。本文对复杂环境下红外图像序列中运动人体目标检测技术进行研究。首先采用基于改进的混合高斯模型(Gaussian mixture model,GMM)的背景减除法对人体目标进行分割,通过多个带有权值的高斯过程来描述复杂变化的背景,对模型个数、权值、学习率进行更新。然后对分割得到感兴趣区域(Region of interest,ROI)采用融合边缘方向累加和特性的梯度方向直方图(Accumulation of oriented edge and histogram of oriented gradient,AOE-HOG)进行特征描述,利用支持向量机(Support vector machine,SVM)实现对人体目标分类检测。实验表明,本文算法能够在复杂场景下正确检测出人体目标,对于多目标距离较近甚至有部分粘连的情形,也具有较好效果。     

一种基于监控视频的出租车识别方法

研究了一种基于视频监控的出租车识别算法.对已经完成跟踪的车辆,通过提取车辆的方向梯度直方图(HOG)特征,作为支持向量机(SVM)分类检测的输入,进行车辆是否为出租车的分类识别.通过多窗口投票机制,增强了分类识别算法的准确性与鲁棒性.实验证明,该方法能准确进行出租车的分类识别,基于实际的标清监控视频,出租车的分类准确率达到90％左右.     

融合颜色和梯度直方图反投影的运动阴影检测

针对智能视频监控中运动阴影影响目标跟踪和识别准确性的问题,提出了一种基于颜色和梯度直方图反投影的阴影检测算法。以视觉背景提取模型检测得到的运动目标区域为基础,首先在HSI颜色空间利用亮度和色度信息筛选出阴影像素,然后通过梯度直方图反投影的方法区分运动目标和阴影,最后将上述两种方法的检测结果进行合理融合得到最终的阴影检测区域。与典型算法的对比实验结果表明,所提算法有效提高了阴影检测的准确性和鲁棒性,适用于运动目标的实时检测和识别。     

基于多特征的视频中单人行为识别

基于视频流的运动人体行为识别是一项既具有挑战性同时又非常具有广阔应用前景的研究课题。行为识别是基于人体目标识别和人体跟踪更高级的计算机视觉部分,研究出一种健壮的行为识别算法具有重要的理论意义和广泛的应用前景。利用在视频的基础上提取出位置分布图、大小分布图等一系列的属性将人的行为进行分类。采用基于帧间差分和改进混合高斯模型的运动人体分割算法,解决了复杂背景下的运动目标检测问题。实验数据对提出的新的行为描述方法进行了各种指标的讨论,验证了本文提出的算法的合理性与高效性。     

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