A novel inverse scattering method to reconstruct the permittivity profile of one-dimensional multi-layered media is proposed in this paper.Based on the equivalent network ofthe medium,a concept of time domain signal f...A novel inverse scattering method to reconstruct the permittivity profile of one-dimensional multi-layered media is proposed in this paper.Based on the equivalent network ofthe medium,a concept of time domain signal flow graph and its basic principles are introduced,from which the reflection coefficient of the medium in time domain can be shown to be a series ofDirac δ-functions(pulse responses).In terms of the pulse responses,we will reconstruct both thepermittivity and the thickness of each layer will accurately be reconstructed.Numerical examplesverify the applicability of this展开更多
5G network is expected to support massive user connections and exponentially increasing wireless services,which makes network security unprecedentedly important.Unlike traditional security-guaranteeing techniques whic...5G network is expected to support massive user connections and exponentially increasing wireless services,which makes network security unprecedentedly important.Unlike traditional security-guaranteeing techniques which rely heavily on cryptographic approaches at upper layers of the protocol stack,physical-layer security(PLS) solutions fully take advantages of the characteristics of wireless channels to degrade the received signal qualities at the malicious users,and realize keyless secure transmission via signal design and signal processing techniques.PLS avoids the difficulties in the distribution and management of secret keys,and provides flexible security levels through adaptive transmission protocol design.Moreover,PLS techniques match the features of 5G networks well.Therefore,the application of PLS to 5G networks is a promising solution to address the security threats.This article presents a comprehensive review of the state-of-the-art PLS techniques,and discusses their applications in 5G networks.We first summarize the principle and advantages of PLS techniques,and point out the reasons why PLS is suitable for 5G networks.Then,we review the existing PLS methods in literature,and highlight severalPLS solutions that are expected to be applied in 5G networks.Finally,we conclude this article and figure out some further research directions.展开更多
Automatic feature extraction and classification algorithm of echo signal of ground penetrating radar is presented. Dyadic wavelet transform and the average energy of the wavelet coefficients are applied in this paper ...Automatic feature extraction and classification algorithm of echo signal of ground penetrating radar is presented. Dyadic wavelet transform and the average energy of the wavelet coefficients are applied in this paper to decompose and extract feature of the echo signal. Then, the extracted feature vector is fed up to a feed forward muhi layer perceptron classifier. Experimental results based on the measured GPR, echo signals obtained from the Mei shan railway are presented.展开更多
A detailed analysis of the influence of Rydberg states to the behavior of GPS satellite signals in the D and E atmospheric layers has been carried out. It is demonstrated that these states are the main reason for the ...A detailed analysis of the influence of Rydberg states to the behavior of GPS satellite signals in the D and E atmospheric layers has been carried out. It is demonstrated that these states are the main reason for the GPS signal distortion. It is shown that the behavior of satellite signals is associated with the spectral characteristics of the UHF radiation of the Rydberg states depending on the geomagnetic conditions of ionosphere. The foundations of the quantum theory of distortion and delay of GPS satellite signal propagation through D and E atmospheric layers are analyzed and expounded. The problem reduces to the resonant scattering of photons, moving in the electromagnetic field of the signal, to the Rydberg complexes populated in a two-temperature non-equilibrium plasma. The processes of creation of additional photons because of stimulated emission and resonance scattering of photons are considered. In the present work, the quantum theory of the propagation of a satellite signal in the Earth’s upper atmosphere, firstly earlier proposed by the same authors, is described in detail. The general problems of the theory and possible theoretical and applied consequences are discussed. It is explained that two main processes occurring here, are directly related to the resonant quantum properties of the propagation medium. The first process leads to a direct increase in the power of the received signal, and second—to a shift in the signal carrier frequency??and the time delay??of its propagation. The main reasons of the processes are scattering of the Rydberg electron by the ion core and presence of the neutral medium molecule in the intermediate autoionization states of the composite system populated by the strong non-adiabatic coupling of electron and nuclear motions. The main purposes of our investigation are the physical justification of the formation of parameters ?and??using the quantum dynamics of the electron behavior in the intermediate state of the Rydberg complex A**M and the estimation of the quantities of??and??in the elementary act of elastic (Rayleigh) photon scattering.展开更多
文摘A novel inverse scattering method to reconstruct the permittivity profile of one-dimensional multi-layered media is proposed in this paper.Based on the equivalent network ofthe medium,a concept of time domain signal flow graph and its basic principles are introduced,from which the reflection coefficient of the medium in time domain can be shown to be a series ofDirac δ-functions(pulse responses).In terms of the pulse responses,we will reconstruct both thepermittivity and the thickness of each layer will accurately be reconstructed.Numerical examplesverify the applicability of this
基金supported in part by the National Natural Science Foundation of China under Grants No.61671369 and 61431011the National Science and Technology Major Project of China under Grant No.2016ZX03001012004+1 种基金the Open Research Fund of the State Key Laboratory of Integrated Services Networks,Xidian University,under Grant No.ISN18-02the Fundamental Research Funds for the Central Universities of China
文摘5G network is expected to support massive user connections and exponentially increasing wireless services,which makes network security unprecedentedly important.Unlike traditional security-guaranteeing techniques which rely heavily on cryptographic approaches at upper layers of the protocol stack,physical-layer security(PLS) solutions fully take advantages of the characteristics of wireless channels to degrade the received signal qualities at the malicious users,and realize keyless secure transmission via signal design and signal processing techniques.PLS avoids the difficulties in the distribution and management of secret keys,and provides flexible security levels through adaptive transmission protocol design.Moreover,PLS techniques match the features of 5G networks well.Therefore,the application of PLS to 5G networks is a promising solution to address the security threats.This article presents a comprehensive review of the state-of-the-art PLS techniques,and discusses their applications in 5G networks.We first summarize the principle and advantages of PLS techniques,and point out the reasons why PLS is suitable for 5G networks.Then,we review the existing PLS methods in literature,and highlight severalPLS solutions that are expected to be applied in 5G networks.Finally,we conclude this article and figure out some further research directions.
基金Supported by the National Natural Science Founda-tion of China (49984001)
文摘Automatic feature extraction and classification algorithm of echo signal of ground penetrating radar is presented. Dyadic wavelet transform and the average energy of the wavelet coefficients are applied in this paper to decompose and extract feature of the echo signal. Then, the extracted feature vector is fed up to a feed forward muhi layer perceptron classifier. Experimental results based on the measured GPR, echo signals obtained from the Mei shan railway are presented.
文摘A detailed analysis of the influence of Rydberg states to the behavior of GPS satellite signals in the D and E atmospheric layers has been carried out. It is demonstrated that these states are the main reason for the GPS signal distortion. It is shown that the behavior of satellite signals is associated with the spectral characteristics of the UHF radiation of the Rydberg states depending on the geomagnetic conditions of ionosphere. The foundations of the quantum theory of distortion and delay of GPS satellite signal propagation through D and E atmospheric layers are analyzed and expounded. The problem reduces to the resonant scattering of photons, moving in the electromagnetic field of the signal, to the Rydberg complexes populated in a two-temperature non-equilibrium plasma. The processes of creation of additional photons because of stimulated emission and resonance scattering of photons are considered. In the present work, the quantum theory of the propagation of a satellite signal in the Earth’s upper atmosphere, firstly earlier proposed by the same authors, is described in detail. The general problems of the theory and possible theoretical and applied consequences are discussed. It is explained that two main processes occurring here, are directly related to the resonant quantum properties of the propagation medium. The first process leads to a direct increase in the power of the received signal, and second—to a shift in the signal carrier frequency??and the time delay??of its propagation. The main reasons of the processes are scattering of the Rydberg electron by the ion core and presence of the neutral medium molecule in the intermediate autoionization states of the composite system populated by the strong non-adiabatic coupling of electron and nuclear motions. The main purposes of our investigation are the physical justification of the formation of parameters ?and??using the quantum dynamics of the electron behavior in the intermediate state of the Rydberg complex A**M and the estimation of the quantities of??and??in the elementary act of elastic (Rayleigh) photon scattering.
