一种基于HWD结构相似的图像质量评价方法

针对传统图像质量评价方法峰值信噪比PSNR和结构相似度SSIM没有充分考虑人眼视觉特性,所得结果有时并不能与人眼的视觉所感知到的实际质量一致的问题,通过对图像结构相似度和人眼视觉系统的研究,文中提出了一种新的基于HWD结构相似的图像质量评价方法。首先对图像进行Hybrid Wavelets and Directional Filter Banks(HWD)分解,提取图像不同频带不同方向上的信息,然后计算各子带结构相似度,最后综合人眼视觉特性的CSF得到图像质量评价值。实验结果表明文中方法相比峰值信噪比PSNR、结构相似度SSIM算法具有更高的准确性和良好的相关性,可以更好的评价图像质量。     

基于人眼失真敏感度的图像质量评价算法研究

人眼作为图像的最终观测者,对图像失真的敏感度会随着图像纹理的变化而变化。根据人眼视觉系统的这一特性,将图像的纹理信息引入到图像质量计算中,提出了一种基于人眼失真敏感度的结构相似度算法(DS-SSIM)。通过对LIVE DATABASE中5种失真类型共779张失真图像的仿真实验得出,相比PSNR,SSIM,ESSIM等算法,DS-SSIM算法的评价结果与人为主观评分具有更高的一致性,更加符合人眼视觉特性。     

基于频率、空间和方向的图像质量评估

将空间域图像质量评价方法结构相似度SSIM推广到HWD变换域,结合人眼视觉倾斜效应和粒子群优化算法,提出一种新的图像质量评价测度。将SSIM直接用于各HWD分解频带,用频带相关性图加权各频带的结构相似度得到局部质量,然后对不同方向的局部质量求加权和得到整幅图像的结构相似度。实验结果表明,该测度与主观感知有较好的一致性,能准确地反映人眼对图像的视觉感知。     

基于图像失真类型的自适应图像质量评价方法

提出了一种图像质量评价方法,所提出的评价算法抽取DCT系数特征来代表图像的失真类型,使用基于支持向量机的分类器对图像失真类型进行预测,随后针对每一种失真类型,给出相应的融合评价算法,对图像进行质量评价.实验结果表明,该算法在整体性能上要优于传统的PSNR及SSIM等图像质量评价算法.     

基于Contourlet视觉模型和奇异值分解的图像质量评价

针对基于像素值的图像质量评价方法忽视图像结构信息和需要完全参考图像等问题,提出了一种基于Contourlet域奇异值分解CW-SVD,部分参考图像质量评价方法(contourlet weighted singular value decomposition)。在Contourlet域中,利用奇异值向量对图像结构的表征能力,结合人眼视觉敏感性确定每个子带的视觉权重,得到每个子带的评价测度,再综合得出图像的最终评价指标。实验表明,该方法应用于4种类型的降质图像质量评价时,比峰值信噪比(PSNR、MSSIM)等算法具有更好的稳定性和更好的主客观评价一致性。     

基于无监督学习的单样本红外图像生成方法

针对当前可见光-红外图像数据集匮乏导致的模型特征学习能力不够以及生成图像质量低下等问题,提出了单样本的无监督学习方法来训练红外图像生成模型。首先,在数据集难以获取、匮乏的情况下,仅采用一对可见光-红外图像作为模型训练的数据,降低了数据获取的难度,解决了数据匮乏的问题。其次,为了在训练模型时充分提取图像特征,改进了网络结构。实验数据表明,本文方法能够在单样本图像生成中取得较好的效果。在艾睿光电数据集中,本文方法的峰值信噪比(Peak Signal-to-Noise Ratio, PSNR)与结构相似性(Structural Similarity, SSIM)指标分别达到了26.5588 dB和0.8846;在俄亥俄州立大学(Ohio State University, OSU)数据集上的PSNR和SSIM分别达到了30.3528 dB和0.9182。与基于风格的生成对抗网络(Style-based Generative Adversarial Network, StyleGAN)方法相比,本文方法在艾睿光电数据集上的PSNR和SSIM指标分别提高了16.07%和23.78%;在OSU数据集上的PSNR和SSIM指标分别提高了31.8%和40.4%。结果表明,本文方法在当前图像质量评价指标方面有较为明显的提高,生成的红外图像纹理细节丰富且接近于真实红外图像。该研究对于今后的红外图像生成技术优化具有一定的参考意义。     

基于小波第二级系数误差的图像质量评价模型

图像质量研究的目标是设计客观评价算法,它与主观评价有很强的相关性.本文根据人眼对图像高低频失真的敏感度不同,采用不同方法分别计算图像高频和低频失真量,然后将两种失真量直接相乘得到客观评价值.实验结果表明,这种客观评价模型能够一致评价各种失真类型、各种失真强度的图像质量,与LIVE图库上差异主观评价分(DMOS)的线性相关性优于PSNR、LMSE和SSIM算法.     

一种基于视觉特性的图像质量评价指标

在分析多通道结构、遮掩效应、敏感度带通特性等人类基本视觉特性（HVS）的基础上,提出了一种新的图像质量评价指标的构造方法。指标构造先借助多尺度几何分析（MGA）中的Contourlet变换对图像进行子带分解以此模拟视觉多通道结构特性,然后在各子带中使用一种遮掩效应模型获取失真图像和参考图像之间的视觉误差,最后通过对比度敏感函数（CSF）获取不同子带的视觉误差加权系数,从而获取图像质量评价值。本文在具有5种类型降质图像的LIVE图库进行性能比较实验,结果表明本文所设计指标比峰值信噪比PSNR、结构相似度SSIM算法具有更好的稳定性和主客观评价一致性。      

基于有约束最小二乘法的IQA算法曲线拟合

为了实现准确评估图像质量评价算法的目标,采纳VQEG报告中提到的性能指标,完成了将算法数据的曲线拟合过程转换为有约束最小二乘法形式的数学模型,然后编写Matlab程序求解。以PSNR、SSIM和MSSIM三种图像质量评价算法为例的评估结果表明,此法结果准确,求解效率高。     

基于剪切波域改进Gamma校正的医学图像增强算法

为了解决医学图像在采集和传输过程中引入噪 声和干扰导致图像质量恶化从而严重影响医学诊断的问题,提出 一种基于剪切波(shearlet)域改进Gamma校正的图像增强方法。首先,通过剪切波变换,把 图像分解成高频 部分和低频部分;其次,用改进的Gamma校正处理剪切波分解后的低频部分以调整图像的整 体对比 度,采用改进的自适应阈值函数对高频部分进行去噪;最后,把剪切波反变换的重构图 像进行模糊对比 增强,以突出图像的细节信息。实验结果表明,本文算法的峰值信噪比(PSNR )、结构相似度(SSIM)和 绝对均值差(MAE)优于其他对比算法,尤其是PSNR的提升更加明显。这些 客观指标说明,本 文算法不仅能有效地抑制噪声,而且能明显改善增强对比度。从主观方面观察,本文算法与 其他算法相比,能获得更好的视觉效果。     

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.     

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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