基于循环谱对称性的频谱感知算法

针对现有基于循环谱的频谱感知算法的不足,利用改进SSCA算法计算接收信号的循环谱,减少算法的计算量;利用循环谱的对称性,选择非零循环频率处的循环谱抵抗干扰和噪声,结合对称性搜索策略进行频谱感知。分析并仿真了循环谱的参数对频谱感知算法的影响,仿真结果证明了所提出算法克服了传统算法的不足,提高了低信噪比下的正确检测性能。

关于一致超图直积的循环指数

设G和H为m-一致超图,G×H为G和H的直积.研究直积G×H的循环指数c(G×H)和因子超图的循环指数c(G),c(H)之间的联系,证明了G×H是谱[c(G),c(H)]-对称的,从而[c(G),c(H)]整除c(G×H),其中[a,b]记正整数a,b的最小公倍数.

N = 4 Supersymmetric Morse Oscillator and Its Spectrum-Generating Algebra

In this paper N = 4 supersymmetry of generalized Morse oscillators in one dimension is studied. Both bound states and scattering states of its four superpartner Hamiltonians are analyzed by using unitary irreducible representations of the noncompact Lie algebra su(1,1). The spectrum-generating algebra governing the Hamiltonian of the N = 4 supersymmetric Morse oscillator is shown to be connected with the realization of Lie superalgebra osp(1,2)or B(0,1) in terms of the variables of a supersymmetric two-dimensional harmonic oscillator.

Density Functional Theory Investigation of Structures and Electronic Spectra of N-protonated Corroles

The geometries and electronic spectra of a series of N-protonated corroles, including unsub- stituted H4Cor＋ and meso-triaryl substituted H4TPC＋, H4TpFPC＋, and H4TdCPC＋, were theoretically studied with density functional theory （DFT）. The results indicate that all these compounds have two conformers, one with C2 symmetry （denoted as Sl） is more stable than the other （denoted as $2, C1 symmetry） by 15.8-18.5 kJ/mol. The corrole macrocycles of these compounds show significant out-of-plane deformation. The enantiomerizations of the chiral S1 conformers were found to be a multi-step process with the $2 conformers as the intermediates. Electronic absorption spectra and electronic circular dichroism （ECD） of these compounds were calculated with time-dependent DFT. In comparison with H4Cor＋, the UV- Vis absorptions of meso-triaryl species are significantly red-shifted and their Q bands are enhanced due to the π-π conjugation between the aryl and corrole rings. Several neighboring electronic transitions were calculated with opposite signs in rotatory strengths, suggesting that ECD spectroscopy may be a useful tool in studying the electronic transitions of these compounds.

Hamiltonian Characterization for Dipolar Coupled Spin Systems

Measuring the Hamiltonian of dipolar coupled spin systems is usually a difficult task due to the high complexity of their spectra. Currently, molecules with unknown geometrical structure and low symmetry are extremely tedious or impossible to analyze by sheer spectral fitting. We present a novel method that addresses the problem of spectral analysis and report experimental results of extracting, by spectral fitting, the parameters of an oriented 6-spin system with very low symmetry in structure, without using apriori knowledge or assumptions on the molecular geometry or order parameters. The advantages of our method are achieved with the use of a new spectral analysis algorithm non-assigned frequency optimization of NMR spectra （NAFONS） and by the use of simplified spectra obtained by transition selective pulses. This new method goes beyond the limit of spectral analysis for dipolar coupled spin systems and is helpful for related fields, such as quantum computation and molecular structure analysis.

Theoretical and experimental investigation on nonlinear interaction among wave groups

Wave group is important in ocean wave theory and applications. In the past, nonlinear interaction among wave groups has been studied on the basis of the nonlinear Sehrrdinger equation. Using this theoretical approach, we found that the nonlinear interaction among wave groups causes asymmetry in the shape of the wave envelope （steeper in the front of the curve of the envelope）. An important consequence of this asymmetry is that the highest wave in a wave group appears one individual wave length ahead of the center of the wave group. Further results show that the degree of envelope asymmetry increases with increasing spectral width and the wave steepness. This theoretical analysis has been supplemented by a systematic experimental study of wind waves. Laboratory and some open sea wave data were analyzed. The results show that the shape of the wind wave envelope of wind waves has the same asymmetry predicted by the theoretical approach. The observed degree of deformation of the envelope also increases with increasing spectral width and the wave steepness as predicted by theory. These conclusions have important ramifications for practical applications of ocean wave theory.

QCD Chiral Phase Transition and Its Microscopic Origin

The transition of strong-interaction matter from the hadronic phase to the quark-gluon plasma phase is a rapid crossover but not a true phase transition in nature.The true phase transition of strong-interaction matter is expected to exist only in certain limits,e.g.chiral limit of massless quarks and etc.In this contribution to CNPC2023 Special Issue we present our recent studies on the true phase transition of strong-interaction matter in the chiral limit of massless quarks as well as its microscopic origin.The study is based on(2+1)-flavor lattice QCD simulations using highly improved staggered fermions,with pion masses ranging from 160 MeV down to 55 MeV.Utilizing a newly proposed method to compute the quark mass derivatives of the Dirac eigenvalue spectrum on the lattice,it is found that the axial U(1)anomaly is still manifested at 1.6T_(c),with a microscopic origin consistent with the dilute instanton gas approximation.Furthermore,based on lattice QCD results and a generalized Banks-Casher relation,it is found that the macroscopic singularity of the chiral phase transition is encoded in the correlation of the Dirac eigenvalue spectrum.Future research directions along these findings are also discussed,including the investigation of the temperature range between T_(c) and 1.6 T_(c) to understand the breakdown of the dilute instanton gas approximation and its connection to the chiral phase transition.

Identification of vibrational mode symmetry and phonon anharmonicity in SbCrSe_(3)single crystal using Raman spectroscopy

Developing an understanding of the physics underlying vibrational phonon modes,which are strongly related to thermal transport,has attracted significant research interest.Herein,we report the successful synthesis of bulk SbCrSe_(3)single crystal and its thermal transport property over the temperature range from 2 to 300 K.Using angle-resolved polarized Raman spectroscopy(ARPRS)and group theory calculation,the vibrational symmetry of each observed Raman mode in the cleaved(001)crystal plane of SbCrSe_(3)is identified for the first time,and then further verified through firstprinciples calculations.The ARPRS results of some Raman modes(e.g.,Ag2~64 cm-1 and Ag 7~185 cm-1)can be adopted to determine the crystalline orientation.More importantly,the temperature dependence of the lattice thermal conductivity(κL)is revealed to be more accurately depicted by the three-phonon scattering processes throughout the measured temperature range,substantiated by in-situ Raman spectroscopy analysis and the model-predictedκL.These results reveal the fundamental physics of thermal transport for SbCrSe_(3)from a completely new perspective and should thus ignite research interest in the thermal properties of other lowdimensional materials using the same strategy.

Spectroscopy of the rotating BTZ black hole via adiabatic invariance

According to Bohr-Sommerfeld quantization rule,an equally spaced horizon area spectrum of a static,spherically symmetric black hole was obtained under an adiabatic invariant action.This method can be extended to the rotating black holes.As an example,this method is applied to the rotating BTZ black hole and the quantized spectrum of the horizon area is obtained.It is shown that the area spectrum of the rotating BTZ black hole is also equally spaced and irrelevant to the rotating parameter,which is consistent with the Bekenstein conjecture.Specifically,the derivation does not need the quasinormal frequencies and the small angular momentum limit.

ON SPECTRUM OF NETWORKS BASED ON MATRIX OF LINK-STATE AND ITS SYMMETRY

This paper constructs a new spectrum of networks by means of the matrix of link-state ofthe network,which can reveal the characteristics of the correlation between the degrees of the network.Also,the computation of this spectrum of networks is usually more feasible and more efficient due tothe much lower order of its matrix of link-state than its adjacent matrix in practice.Some estimatesfor the bounds of the key eigenvalues in the spectrum are obtained,the corresponding inequalities arepresented and proved.For the sake of its application,the authors define spectrum of networks in twoways,and all theorems are given in parallel for both kinds of definition.In addition,the authors finda symmetry in the spectrum,which is relative to the characteristic of structure of its network to someextent.

Neutrino Mixing in the BLMSSM

Abstract In recent years, a nonzero value for the neutrino mixing angle θ13 has been successively measured by the international famous reactor oscillation experiments, which is greater than 5 standard deviations. Our study is in the framework of the MSSM, where baryon and lepton numbers are local gauged symmetries （BLMSSM）. This model can generate three tiny neutrino masses at the tree level through TeV scale seesaw mechanism. In our paper, we analyze the neutrino masses and their corresponding mixing angles with a ＂top-down＂ method, assuming neutrino mass spectrum with normal ordering （NO） and inverted ordering （IO）.