Quaternion higher-order spectra and their invariants for color image recognition

This paper describes an invariants generation method for color images, which could be a useful tool in color object recognition tasks. First, by using the algebra of quaternions, we introduce the definition of quaternion higher-order spectra (QHOS) in the spatial domain and derive its equivalent form in the frequency domain. Then, QHOS invariants with respect to rotation, translation, and scaling transformations for color images are constructed using the central slice theorem and quaternion bispectral analysis. The feature data are further reduced to a smaller set using quaternion principal component analysis. The proposed method can deal with color images in a holistic manner, and the constructed QHOS invariants are highly immune to background noise. Experimental results show that the extracted QHOS invariants form compact and isolated clusters, and that a simple minimum distance classifier can yield high recognition accuracy.     

对甲氧基苯甲腈的单色共振双光子电离光谱

对甲氧基苯甲腈是一种重要的化学化工原料,本文采用超声分子束技术和共振多光子电离方法获得了对甲氧基苯甲腈的单色共振双光子电离光谱,基态S0到电子激发态S1的0←0跃迁被确定为(35549±2)cm~(-1),结合含时密度泛函理论计算结果对观察到的光谱进行了振动模式标识和描述.实验发现呼吸振动模非常易于激活,其基频和二次泛频光谱很强,三次泛频也可明确标识,观察到大量呼吸振动与其他正则模的结合振动,这是对甲氧基苯甲腈不同于常见的多原子分子的一个重要特性.这些结果为研究对甲氧基苯甲腈的里德堡态、动力学和零动能光谱等提供了重要的参考数据.     

Principal component and sampling analysis of color spectra

We studied the effect and relation between the optimal sampling interval and the optimal number of principal component analysis eigenvectors for color spectra. The effect of different type of light sources and illuminants are included in the study. Several reflectance spectra sets under different real light sources and standard illuminants were used as a test set. The needed sampling interval and number eigenvectors with different light sources and illuminants are found. The used bandwidth in measurements causes effect to the resulted optimal sampling interval, which is also shown.     

Far-infrared spectra of color centers in alkali halides

Abstract

In this paper we wish to review some recent results on the effects of color centers on the vibrational properties of alkali halide crystals.     

Analysis of noise properties of an optocoupler device

In the paper, localization of a source of random telegraph signal noise (RTS noise) in optocoupler devices of CNY 17 type was defined. The equivalent noise circuit in low frequency noise for these types of optocouplers was proposed.     

Design of unit cells and demonstration of methods for synthesizing Huygens metasurfaces

The systematic design of unit cells for a Huygens metasurface, a particular class of metasurface, is presented here. The design of these unit cells uses transmission-line theory. This is validated through application to 1D refraction and Gaussian-to-Gaussian beam focusing. The 1D refraction is further validated experimentally. These applications demonstrate the practical utility of these Huygens metasurfaces. The Huygens metasurfaces presented here are printed on two bonded boards instead of many stacked, interspaced layers. This simplifies fabrication and enables the scaling down of the metasurfaces to shorter wavelengths. These two bonded boards implement a single, collocated layer of electric and magnetic dipoles. The electric and magnetic dipoles are synthesized using sub-wavelength arrays of printed elements. These printed elements can be manufactured using standard PCB fabrication techniques, and are capable of synthesizing the full range of impedances required. Furthermore, in contrast to frequency-selective surfaces (FSSs) and traditional transmitarrays, which are on the order of a wavelength thick, these designs are only λ/10 thick while incurring minimum reflections losses.     

Temporal evolution of the emission spectra of color center lasers

The mode spectrum of a homogeneously broadened laser is mainly influenced by mode competition effects. In this paper the temporal evolution of the emission spectra of color center lasers caused by mode competition is investigated. The results are compared with a theoretical estimation.Dedicated to Prof. Dr. Herbert Welling on the occasion of his 60th birthday     

Design of a color coded target for vision measurements

As a category of special control points which can be automatically identified, artificial coded targets have been widely developed in the field of computer vision, photogrammetry, augmented reality, etc. In this study, a novel color coded target is designed for vision measurements. A reference position is defined to avoid the repeated coding as well as simplify the coding structure, and a pair of concentric circles is utilized for the precise location of the target. An edge-based identification and location algorithm is proposed for the designed coded target. In this algorithm, a coarse-fine strategy is employed to improve the efficiency and various judgments are made to ensure the correctness of the identification. No human involvement is required except for the adjustment of thresholds in the beginning, which is conducive to the automation of measurement. The algorithm shows high accuracy and robustness in experiments.     

The scattering spectra and color of disperse systems of weakly absorbing particles

The scattering spectra of weakly absorbing systems of spherical particles are calculated using various approximate and numerical methods. Comparative estimates are made for applicability of the single-scattering and mean-field approximations and the Monte Carlo computer simulation for different scattering multiplicities. The results of the calculations well agree with the experimental scattering spectra of the crystalline lens. Based on the spectral characteristics obtained, the chromaticity coordinates are calculated and regularities in variations of the color characteristics are analyzed as functions of the disperse system parameters.     

彩色变焦照明系统设计

针对基于RGB混色技术在小角度、近距离空间内较难实现彩色LED,且有关彩色变焦照明相关文献也较少的问题,设计了一款彩色变焦照明系统。系统主要由LED光源、TIR透镜、微结构透镜组成,可在650mm处实现良好混色照明,变焦范围为4.2°~9.1°(半光强角),且变焦照明过程中,在光强下降为20%的角度内能量利用率达85%以上,半光强角内的能量利用率始终在75%以上,满足设计要求。     

Peculiarities of absorption and luminescence spectra of nitrogen-vacancy color centers in diamond crystals

We have studied photoluminescence spectra of nitrogen-vacancy (NV) centers upon their pumping by short-wavelength visible and near-UV radiation. We have shown that NV⁰ centers, as distinct from NV^? centers have an absorption line in the UV range. Inversion of the zero-phonon line of NV^? centers has been shown and interpreted.     

一种小型光谱色彩分析仪的设计

为解决目前颜色测量仪器测速慢、体积大的问题，采用先进的颜色测量方法——光电摄谱法，建立了一个测色的数学模型，设计了一种全自动测色的小型光谱色彩分析仪。仪 器由照明系统、光电摄谱仪、信号采集与处理电路、测色软件四部分组成。详细阐述了照明系统和光电摄谱仪的设计。光电摄谱仪采用平场凹面光栅分光，线阵CCD接收，缩小了仪 器体积。利用此仪器测量7块标准色板，色品坐标测量不确定度小于0.01，测试周期为1秒。结果表明，此仪器不仅精度高，还满足了工业生产中对测色的速度和准确度要求。     

碳化硅合成反应动力学研究

基于经典轨迹法研究了碳化硅合成反应C(3Pg) SiO(X1∑ ,V=0,1;J=0)→SiC(X1∑ ) O(3Pg)的动力学.该反应存在阈能,反应截面均存在一个极大值和最佳反应能量.当SiO(X1∑ )分别处于V=0、J=0和V=1、J=0状态时,反应阈能分别约为1.2552×103kJ.mol-1和1.1297×103kJ.mol-1,反应截面极大值分别为5.3742×10-3nm2和5.1824×10-3nm2,而最佳初始碰撞能Et(the Optimal InitialCollision Translation Energy)分别为3.3472×103kJ.mol-1和3.7656×103kJ.mol-1.在SiC的最佳产率区(即最佳反应能区),通过反应物的振动激发并不能使SiC产率明显提高,因此基态下SiC合成反应的最佳能区即为该反应的最佳产率区.