Scattering off of an instanton

We consider the scattering of a classical colored particle off an instanton. That is, we investigate Wong's equations (or equivalently, the Kaluza-Klein geodesic equations) for a colorSU(2) particle under the influence of a Euclidean instanton. We solve the equations in the limit in which the instanton becomes singular. Our main result is that particles with head-on trajectories scatter off the instanton with a scattering angle of π/3. This angle is independent of the magnitude of the color charge and velocity of the particle as long as both are nonzero. The plane in which the scattering takes place is determined by the particle's initial position and color charge. We also solve for the geodesics for the corresponding (singular) Kaluza-Klein metric onS ⁷.     

Stimulated Raman scattering of pre-gaussian light

The quantum theory of a forward Stokes generation by means of stimulated Raman scattering is considered in the case of a pre-gaussian pump composed by two and three telegraphs. As for the case of a colored chaotic pump the mean Stokes intensity is found to be enhanced over that resulting from a coherent pump in both transient and steady-state limits. In the limit that the pre-gaussian bandwidth becomes large, the mean Stokes intensity also becomes identical with that resulting from a coherent pump.     

e+e−-Annihilation into hadrons and unified theories

It is argued that unified gauge theories of weak, electromagnetic and strong interactions lead naturally to the introduction of new hadronic constituents which carry both color and electric charged and are colored counterparts of the W-bosons mediating the weak interactions. Consequences for e⁺e^?-annihilation and deep inelastic scattering are discussed.     

Thermally activated structural changes in KCl crystals containing color centers

Structural changes taking place in the temperature interval 300–750K in KCl crystals additively colored in Na vapor are studied by spectrophotometric and light scattering methods in conjunction with crystal lattice constant measurement.Translated from Izvestiya Vysshikh Uchebnykh Zavedenii, Fizika, No. 9, pp. 39–45, September, 1984.     

一些异核双金属有机化合物的FT－Raman光谱

一些异核双金属有机化合物的ＦＴ－Ｒａｍａｎ光谱郭建华，谭，聂崇实（中国科学院上海有机化学研究所上海市２０００３２）ＦＴ－ＲａｍａｎＳｐｅｃｔｒａｏｆＳｏｍｅＨｅｔｅｒｏｂｉｎｕｃｌｅａｒＭｅｔａｌｌｏｒｇａｎｉｃＣｏｍｐｏｕｎｄｓ￥ＪｉａｎＨｕａＧｕ...     

Statistical model of the habit and arrangement of mineral crystals in the collagen of bone

Randomly colored space tesselations are considered as models for the mineral/organic structure of bone. First, it is shown that the structure function for such models is always proportional to the average form factor of the individual tiles and hence independent of the mineral density in the sample. Then the structure function is calculated for three such models: for model I, based on a hexagonal, and model 2, on a Poisson-Voronoi tesselation of the plane and for model 3, based on a random tesselation of the line. These results are compared to experimental structure functions measured by small-angle scattering and excellent agreement is obtained between model 2 and the bone from mice and rats, as well as between model 3 and calcified turkey leg tendon. Divergent conclusions following recent experiments by small-angle x-ray scattering and by electron microscopy are discussed in the light of these structural models and an explanation is proposed which might remove the discrepancy.Dedicated to Prof. Oliver Penrose on the occasion of his 65th birthday.     

Determination by Raman scattering of the nature of pigments in cultured freshwater pearls from the mollusk Hyriopsis cumingi

The nature of pigments in naturally colored pearls is still under discussion. For this study, Raman scattering measurements were obtained for 30 untreated freshwater cultured pearls from the mollusk Hyriopsis cumingi covering their typical range of colors. The originality of this work is that seven different excitation wavelengths (1064 nm, 676.44 nm, 647.14 nm, 514.53 nm, 487.98 nm, 457.94 nm, 363.80 nm) are used for the same samples at the highest possible resolution. All colored pearls show the two major Raman features of polyenic compounds assigned to double carbon–carbon (CC) – at about 1500 cm⁻¹ – and single carbon–carbon (C C) – at about 1130 cm⁻¹ – bond stretching mode, regardless of their specific hue. These peaks are not detected in the corresponding white pearls, and therefore seem directly related to the major cause of body color. Additionally, the exact position of CC stretching vibration shows that these compounds are not members of the carotenoid family. Moreover, some changes are observed in intensities, shape and positions of the two main characteristic polyenic peaks from one sample to the next. Similar changes are observed also using several excitation wavelengths for the same point of the same pearl. The exact position of C C stretching vibration of polyenic molecules depends strongly on the number of double bonds (N) contained in their polyenic chain. Hence, using a constrained decomposition of this band for different excitation wavelengths, up to nine different pigments may be detected in the same pearl. Their general chemical formula is R‐( CHCH )_N‐R′ with N = 6–14. All our colored samples contained at least four pigments (N = 8–11). Different colors are explained by different mixtures, not by a simple change of pigment. The chemical nature of the chain ends is still unknown, because it cannot be detected with Raman scattering. However, it is possible that these polyenes are complexed with carbonate molecules of the nacre. Similar coloration mechanisms are found in products from other living organisms (e.g. parrots feathers). Moreover, it seems that a similar series of pigments is found in other pearls also, as well as in some marine animals living in similar environments (e.g. corals). Copyright © 2006 John Wiley & Sons, Ltd.     

Signal-to-noise ratio enhancement based on the whitening transformation of colored structural noise

In the ultrasonic testing and evaluation of highly scattering materials (i.e. non-homogeneous media such as composites, layered and clad materials) structural noise is an important limitation to the visibility of flaw echoes. This noise cannot be reduced by conventional linear filtering or by time-averaging techniques. In order to enhance the defect-to-background noise ratio (SNR), many different algorithms have been developed over the years. This work analyzes three new strategies for SNR enhancement based on the whitening transformation of the colored structural noise. By using this transformation, the small spectral differences between noise and flaw echoes are exploited, thereby allowing an improvement in the visibility of the flaw.     

关联噪声驱动的非对称双稳系统的随机共振

运用统一色噪声近似理论和两态模型理论,研究了周期矩形信号和关联的乘性色噪声和加性白噪声驱动的非对称双稳系统的随机共振现象,得到了适合信号任意幅值的信噪比表达式.信噪比是乘性噪声强度、加性噪声强度、乘性噪声自关联时间、噪声耦合强度的非单调函数,所以该双稳系统中出现了随机共振.同时,调节加性噪声强度比调节乘性噪声强度更容易产生随机共振.势阱静态非对称性和噪声之间的耦合强度对信噪比的影响是不同的. 关键词： 非对称双稳系统 随机共振 信噪比 周期矩形信号     

On the normal ordering of multi-mode boson operators

Combinatorial aspects of normal ordering for annihilation and creation operators of a multi-mode boson system are discussed. The modes are assumed to be coupled, since otherwise the problem of normal ordering is reduced to the cooresponding problem of the single-mode case. To describe the normal ordering in the multi-mode case, for each mode, a color is introduced, and colored contractions are considered. A depiction for colored contractions via colored linear representations is given. By analogy with the single-mode case, associated colored Stirling numbers are defined as coefficients appearing in the process of normal ordering for powers of the number operators. Several properties of these colored Stirling numbers are discussed.     

Analysis of visual perception of light emitting diode brightness in dense fog with various droplet sizes

Road signs must provide a conspicuous signal to a wide variety of drivers over a broad range of environmental and geometric conditions. Recently, there are an increasing number of applications in which light emitting diodes (LEDs) are used as the light source, including critical transportation signaling. In the presence of fog, the resulting visual signal is disturbed due to light scattering by airborne water droplets. By measuring LED brightness with human spectral sensitivity in various densities and various droplet sizes (10, 30, 50, and 100 μm), it is understood that the particle size distribution (fog droplet size) and density of fog does affect visibility in fog. The colored LEDs that contain a yellow component had high brightness evaluation, blue component had low brightness evaluation in all densities and different droplet sizes. The result in this paper can contribute to air and land traffic safety and the prevention of accidents.     

基于CCF-TLS-ESPRIT算法的低频振荡在线辨识

低频振荡在线辨识需用到广域测量系统(WAMS)的采集信号,而WAMS采集的信号中常伴有高斯白噪声,经过常规的低通滤波处理后会产生高斯色噪声,从而影响辨识的精度.针对在线辨识中的色噪声问题,提出以互相关函数(CCF)来代替实测信号,从而抑制色噪声,并结合总体最小二乘-旋转不变技术参数估计(TLS-ESPRIT)算法进行模态辨识.仿真结果表明,CCF-TLS-ESPRIT算法能够有效辨识出色噪声环境中的系统低频振荡模态,并具有一定的效率.     

色关联的乘性和加性色噪声激励下分段非线性模型的随机共振

研究了色关联的乘性和加性高斯色噪声与外周期信号共同激励下,分段非线性系统的随机共振.利用一致有色噪声近似和两态模型理论,推导出系统稳态概率密度和信噪比的解析表达式,分析了色噪声和周期信号对随机共振的影响,发现系统中存在传统的随机共振和真实的随机共振现象.同时,系统的信噪比曲线的峰值随着噪声互关联系数和互关联时间的增加而减小.     

Effect of Asymmetric Potential and Gaussian Colored Noise on Stochastic Resonance

The phenomenon of stochastic resonance （SR） in a bistable nonlinear system is studied when the system is driven by the asymmetric potential and additive Gaussian colored noise. Using the unified colored noise approximation method, the additive Gaussian colored noise can be simplified to additive Gaussian white noise. The signal-to-noise ratio （SNR） is calculated according to the generalized two-state theory （shown in [H.S. Wio and S. Bouzat, Brazilian J.Phys. 29 （1999） 136]）. We find that the SNR increases with the proximity of a to zero. In addition, the correlation time T between the additive Gaussian colored noise is also an ingredient to improve SR. The shorter the correlation time T between the Gaussian additive colored noise is, the higher of the peak value of SNR.     

非自治拉曼多色孤子的管理和传输

以变系数的非自治非线性薛定谔方程为模型,考虑了一种色散、非线性和自发拉曼散射效应管理下的非自治系统,通过简单变换显式给出了该系统的精确非自治拉曼多色孤子解。基于精确孤子解,解析研究了该拉曼多色孤子在非自治管理系统中的演化特性,发现孤子的中心位置、波数与色散和非线性以及拉曼效应有关,而孤子频移仅与拉曼效应的参数决定,拉曼效应主导了非自治孤子的自频移,引起了孤子的频移在传输过程中不断的发生变化,导致了孤子的多色性。另外,我们数值讨论了该非自治孤子的传输稳定性,结果表明:该非自治拉曼多色孤子在有限的扰动下具有较好的稳定性。     

Colored extension of GL q(2) and its dual algebra

We address the problem of duality between the colored extension of the quantized algebra of functions on a group and that of its quantized universal enveloping algebra, i.e., its dual. In particular, we derive explicitly the algebra dual to the colored extension of GL _q(2) using the colored RLL relations and exhibit its Hopf structure. This leads to a colored generalization of the R-matrix procedure to construct a bicovariant differential calculus on the colored version of GL _q(2). In addition, we also propose a colored generalization of the geometric approach to quantum group duality given by Sudbery and Dobrev.     

Colored Quantum Algebra and Its Bethe State

We investigate the colored Yang-Baxter equation. Based on a trigonometric solution of colored Yang-Baxter equation, we construct a colored quantum algebra. Moreover we discuss its algebraic Bethe ansatz state and highest wight representation.     

Colored Noise in First-order-like Phase Transition of a Laser System

The decoupling theory is employed to analyze the multiplicative colored noise in a single mode laser system. Steady state intensity distribution function is derived when colored noise is included in the laser system. The first-order-like phase transition driven by multiplicative colored noise is investigated and compared with the case of multiplicative white noise. It is shown that the noise correlation time can affect the parameter plane of the first-order-like phase transition. The steady state intensity distributions in a laser system is changed greatly with noise correlation time τ.