Wigner分布的模糊处理

针对Wigner分布在应用中物理意义含混不清等特点,提出时频分布具有模糊性的观点。将模糊集的概念和方法引入对时频分析结果的理解和再处理,提出了模糊时频点的概念和对Wigner分布进行模糊点处理的方法,将此方法用于实际信号的处理,效果良好。     

Wigner distribution function display of complex 1D signals

Three optical methods are proposed for the production of the Wigner distribution function (WDF). This function offers an alternative way of representing signals. The WDF depends simultaneously on time (or space) and on frequency. For the production of the WDF we distinguish between real signals, holograms of complex signals and truly complex signals. An important special class of signals are pure-phase functions. The WDF of such phase functions is very useful for testing optical phase structures. Our setups can also be employed for the production of the ambiguity function.     

The Wigner distribution function applied to optical signals and systems

In this paper the Wigner distribution function has been introduced for optical signals and systems. The Wigner distribution function of an optical signal appears to be in close resemblance to the ray concept in geometrical optics. This resemblance reaches even farther: although derived from Fourier optics, the Wigner distribution functions of some elementary optical systems can directly be interpreted in terms of geometrical optics.     

Wigner transformation,momentum space topology,and anomalous transport

Using derivative expansion applied to the Wigner transform of the two- point Green function we analyse the anomalous quantum Hall effect (AQHE), and the chiral magnetic effect (CME). The corresponding currents are proportional to the momentum space topological invariants. We reproduce the conventional expression for the Hall conductivity in 2+1$2+1$ D. In 3+1$3+1$ D our analysis allows to explain systematically the AQHE in topological insulators and Weyl semimetals. At the same time using this method it may be proved, that the equilibrium CME is absent in the wide class of solids, as well as in the properly regularized relativistic quantum field theory.     

Optical processing of one-dimensional signals

Long one-dimensional signals can be processed efficiently by optical methods if they are represented in a two-dimensional version. We show that by choosing an appropriate scanning pattern either new types of operations can be synthesized or classical operations like Fourier transformation or correlation can be implemented for this type of signals. Besides coherent illumination, incoherent light can also be used in order to reduce stability requirements, to increase the signal to noise ratio and to accommodate self-luminous inputs.     

On the Radon transformation of Wigner function altered with various optical processes

We discuss what happens to the Radon transformation of signal's Wigner functions (i.e., signal's Wigner transformation (WT)) if the signal function undergoes various optical processes, such as Fraunhofer diffraction, lens transformation and Fresnel diffraction, etc. Because the usual Wigner transforms can be studied via their corresponding transforms of the Wigner operator, we use the Weyl ordered form of the Wigner operator and the Weyl ordering invariance under similar transformations to derive the result, we find that the alteration of Radon transformation of signal's Wigner function (or named the variation of tomogram function), through these optical processes, can be ascribed to the variation of Radon transformation parameters once the parameter of WT is given.     

数字信号在原子芯片中的应用

通过分析和计算不同谐波分量与原子相互作用产生不同的势场,发现可以将其叠加在一起形成原子囚禁势,提出了数字信号在原子芯片中的应用方案. 关键词： 原子芯片 数字信号 绝热势     

Reduction of speckle noise in digital holography by using digital image processing

A fundamental problem in optical and digital holography is the presence of speckle noise in the reconstruction process. Many approaches have been carried out in order to overcome such a problem ranging from modifying the spatial coherence of the illumination (optical techniques) to image processing techniques (digital techniques). This work shows the merged use of digital image processing techniques in order to reduce the speckle noise in digital reconstruction of optically recorded Fresnel's holograms. The proposed filtering techniques are illustrated with experimental results.     

New transformation of Wigner operator in phase space quantum mechanics for the two-mode entangled case

As a natural and important extension of Fan's paper (Fan Hong-Yi 2010 Chin. Phys. B 19 040305) by employing the formula of operators' Weyl ordering expansion and the bipartite entangled state representation this paper finds a new two-fold complex integration transformation about the Wigner operator Δ ( μ,v ) (in its entangled form) in phase space quantum mechanics, and its inverse transformation. In this way, some operator ordering problems regarding to ( a₁⁺-a₂) and (a₁+a₂⁺) can be solved and the contents of phase space quantum mechanics can be enriched, where a_i,a_i⁺ are bosonic creation and annihilation operators, respectively.     

Application of digital signal processing in nuclear spectroscopy

Digital signal processing algorithms for nuclear particle spectroscopy are described. The algorithms are presented as recursive procedures, which can easily be programmed using modern computer programming languages. The input data flow was formed by particle detector pulses, preprocessed by a charge-sensitive preamplifier and transformed into a sequence of equidistantly sampled signals by a sampling analog-to-digital converter. The pile-up elimination procedure, the influence of the number of bits of the sampling analog-to-digital converter on the energy resolution of the spectrometer, and ballistic deficit correction are also considered. The pile-up elimination method was developed for fission fragment spectroscopy in the case of high α radioactivity of fissile targets (²³⁹Pu, ²⁴¹Am) using a Frisch-grid double ionization chamber. Since the intrinsic energy resolution of a spectrometer based on a double ionization chamber is much worse than that determined by the noise level of the charge-sensitive amplifier, an ultrapure germanium detector was used to provide the highest sensitivity to the errors introduced by measuring procedures. The effect of pile-up elimination procedure on the energy resolution was experimentally investigated at different source intensities. The main characteristics of the developed algorithms are compared with those of other processing procedures published in the literature.     

Estimation of parameters of motion of a moving sound source by digital processing of a set of Doppler-shifted underwater acoustic signals

A method is proposed for estimating the parameters of motion of a moving sound source on the basis of digital processing of Doppler-shifted underwater acoustic signals received by a set of hydrophones. A two-step approximation algorithm is used. An example of implementing the method of estimating the parameters of motion is presented for a two-hydrophone receiving system. Errors in estimating the parameters by means of the proposed method are considered.     

New transformation for optical signal processing

The use of the optical Mellin transform in several novel optical signal processing applications using the frequency plane correlator and joint transform correlator is discussed.