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Optical Nonlinearity of Violet Phosphorus and Applications in Fiber Lasers

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Chinese Physics Letters 2024年第1期41卷 16-20页

作者：杨慧苒齐梦婷李旭鹏薛泽鲁晨浩成嘉伟韩冬冬李璐 School of Science Xi’an University of Posts and TelecommunicationsXi’an 710121China China Academy of Space Technology(xi’an) Xi’an 710100China School of Electronic Engineering Xi’an University of Posts and TelecommunicationsXi’an 710121China

A D-shaped fiber is coated with a new two-dimensional nanomaterial,violet phosphorus(VP),to create a saturable absorber(SA)with a modulation depth of 3.68%.Subsequently,the SA is inserted into a fiber laser,enabling successful generation of dark solitons and bright–dark soliton pairs through adjustment of the polarization state within the cavity.Through further study,mode-locked pulses are achieved,proving the existence of polarization-locked vector solitons.The results indicate that VP can be used as a polarization-independent SA.

关键词： polarization fiber absorber

L_(2,1)-norm robust regularized extreme learning machine for regression using CCCP method

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The Journal of China Universities of posts and telecommunications 2023年第2期30卷 61-72页

作者： Wu Qing Wang Fan Fan Jiulun Hou Jing School of Automation Xi'an University of Posts and TelecommunicationsXi'an 710121China School of Telecommunication and Information Engineering&School of Artificial Intelligence Xi'an University of Posts and TelecommunicationsXi'an 710121China School of Humanities and Foreign Languages Xi'an University of Posts and TelecommunicationsXi'an 710121China

As a way of training a single hidden layer feedforward network(SLFN),extreme learning machine(ELM)is rapidly becoming popular due to its efficiency.However,ELM tends to overfitting,which makes the model sensitive to noise and outliers.To solve this problem,L_(2,1)-norm is introduced to ELM and an L_(2,1)-norm robust regularized ELM(L_(2,1)-RRELM)was proposed.L_(2,1)-RRELM gives constant penalties to outliers to reduce their adverse effects by replacing least square loss function with a non-convex loss function.In light of the non-convex feature of L_(2,1)-RRELM,the concave-convex procedure(CCCP)is applied to solve its model.The convergence of L_(2,1)-RRELM is also given to show its robustness.In order to further verify the effectiveness of L_(2,1)-RRELM,it is compared with the three popular extreme learning algorithms based on the artificial dataset and university of California Irvine(UCI)datasets.And each algorithm in different noise environments is tested with two evaluation criterions root mean square error(RMSE)and fitness.The results of the simulation indicate that L_(2,1)-RRELM has smaller RMSE and greater fitness under different noise settings.Numerical analysis shows that L_(2,1)-RRELM has better generalization performance,stronger robustness,and higher anti-noise ability and fitness.

关键词： extreme learning machine(ELM) non-convex loss L_(2,1)-norm concave-convex procedure(CCCP)

Infrared image enhancement based on adaptive weighted guided filter

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The Journal of China Universities of posts and telecommunications 2022年第2期29卷 73-84页

作者： Lu Ying Huang Shiqi Wang Wenqing Sun Ke School of Automation Xi’an University of Posts and TelecommunicationsXi'an 710121China xi’an Key Laboratory of Advanced Control and Intelligent Processing Xi’an University of Posts and TelecommunicationsXi'an 710121China

The physical principle of infrared imaging leads to the low contrast of the whole image,the blurring of contour and edge details,and it is also sensitive to noise.To improve the quality of infrared image and visual effect,an adaptive weighted guided filter(AWGF) for infrared image enhancement algorithm was proposed.The core idea of AWGF algorithm is to propose an adaptive strategy to update the weights of guided filter(GF) parameters,which not only improves the accuracy of regularization parameter estimation in GF theory,but also achieves the purpose of removing infrared image noise and improving its detail contrast.A large number of real infrared images were used to verify AWGF algorithm,and good experimental results were obtained.Compared with other guided filtering algorithms,the halo phenomenon at the edge of infrared images processed by the AWGF algorithm is significantly avoided,and the evaluation parameter values of information entropy(IE),average gradient(AG),and moment of inertia(MI)are relatively high.This shows that the quality of infrared image processed by the AWGF algorithm is better.

关键词： infrared image guided filter(GF) adaptive weight image enhancement regularization parameter

Janus MSiGeN_(4)(M=Zr and Hf)monolayers derived from centrosymmetricβ-MA_(2)Z_(4):A first-principles study

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Journal of Semiconductors 2021年第12期42卷 22-28页

作者： xiaoshu Guo Sandong Guo xi'an university of posts and telecommunications Xi'an 710121China School of Electronic Engineering Xi'an University of Posts and TelecommunicationsXi'an 710121China

A two-dimensional(2D)MA_(2)Z_(4)family with and phases has been attracting tremendous interest,the MoSi_(2)N_(4)and WSi_(2)N_(4)of which have been successfully fabricated(Science 369,670(2020)).Janus monolayers have been achieved in many 2D families,so it is interesting to construct a Janus monolayer from the MA_(2)Z_(4)family.In this work,Janus MSiGeN4(M=Zr and Hf)monolayers are predicted from-MA_(2)Z_(4),which exhibit dynamic,mechanical and thermal stabilities.It is found that they are indirect band-gap semiconductors by using generalized gradient approximation(GGA)plus spin-orbit coupling(SOC).With biaxial strain a/a0 from 0.90 to 1.10,the energy band gap shows a nonmonotonic behavior due to a change of conduction band minimum(CBM).A semiconductor to metal transition can be induced by both compressive and tensile strains,and the phase trans-formation point is about 0.96 for compressive strain and 1.10 for tensile strain.The tensile strain can change the positions of CBM and valence band maximum(VBM),and can also induce the weak Rashba-type spin splitting near CBM.For MSiGeN4(M=Zr and Hf)monolayers,both an in-plane and out-of-plane piezoelectric response can be produced,when a uniaxial strain in the basal plane is applied,which reveals the potential as piezoelectric 2D materials.The high absorption coefficients in the visible light region suggest that MSiGeN4(M=Zr and Hf)monolayers have potential photocatalytic applications.Our works provide an idea to achieve a Janus structure from the MA_(2)Z_(4)family,and can hopefully inspire further research exploring Janus MA_(2)Z_(4)monolayers.

关键词： Janus monolayers piezoelectronics MA_(2)Z_(4)family

Certificateless broadcast multi-signature for network coding

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Frontiers of Information Technology & Electronic Engineering 2022年第9期23卷 1369-1377页

作者： Huifang Yu Zhewei QI School of Cyberspace Security Xi’an University of Posts and TelecommunicationsXi’an710121China

Network coding can save wireless network resources and is very fast in comparison with traditional routing.In real application scenarios,network coding is vulnerable to pollution attacks and forgery attacks.To solve these problems,the certificateless broadcast multi-signature for network coding(NC-CLBMS)method is devised,where each source node user generates a multisignature about the message vector,and the intermediate node linearly combines the received data.NC-CLBMS is a multi-source multi-signature method with anti-pollution and anti-forgery advantages;moreover,it has a fixed signature length and its computation efficiency is very high.NC-CLBMS has extensive application prospects in unmanned aerial vehicle(UAV)communication networks,fifth-generation wireless networks,wireless sensor networks,mobile wireless networks,and Internet of Vehicles.

关键词： Network coding Certificateless multi-signature Linear combination Homomorphic hash function

Passive Localization of Signal Source Based on UAVs in Complex Environment

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China Communications 2020年第2期17卷 107-116页

作者： Pengwu Wan Qiongdan Huang Guangyue Lu Jin Wang Qianli Yan Yufei Chen Xi’an University of Posts and Telecommunications

For the influence caused by multipath fading and non-line-of-sight(NLOS)transmission,it is challenging to accurately localize a moving signal source in complex environment by using the wireless sensor network(WSN)on the ground.In this paper,we establish a special WSN in the sky to address this challenge,where each sensor is loaded on an unmanned aerial vehicle(UAV)and the operation center of all the UAVs is fixed on the ground.Based on the analyzing of the optimal distribution and the position error calibration of all the sensors,we formulate the localization scheme to estimate the position of the target source,which combines the time difference of arrival(TDOA)method and the frequency difference of arrival(FDOA)method.Then by employing the semidefinite programming approach,we accurately obtain the position and velocity of the signal source.In the simulation,the validity of the proposed method is verified through the performance comparison.

关键词： passive localization time difference of arrival wireless sensor network unmanned aerial vehicle semidefinite programming

A novel feature extraction method for ship-radiated noise

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Defence Technology（防务技术） 2022年第4期18卷 604-617页

作者： Hong Yang Lu-lu Li Guo-hui Li Qian-ru Guan School of Electronic Engineering Xi’an University of Posts and TelecommunicationsXi’anShaanxi710121China

To improve the feature extraction of ship-radiated noise in a complex ocean environment,a novel feature extraction method for ship-radiated noise based on complete ensemble empirical mode decomposition with adaptive selective noise(CEEMDASN) and refined composite multiscale fluctuation-based dispersion entropy(RCMFDE) is proposed.CEEMDASN is proposed in this paper which takes into account the high frequency intermittent components when decomposing the signal.In addition,RCMFDE is also proposed in this paper which refines the preprocessing process of the original signal based on composite multi-scale theory.Firstly,the original signal is decomposed into several intrinsic mode functions(IMFs)by CEEMDASN.Energy distribution ratio(EDR) and average energy distribution ratio(AEDR) of all IMF components are calculated.Then,the IMF with the minimum difference between EDR and AEDR(MEDR)is selected as characteristic IMF.The RCMFDE of characteristic IMF is estimated as the feature vectors of ship-radiated noise.Finally,these feature vectors are sent to self-organizing map(SOM) for classifying and identifying.The proposed method is applied to the feature extraction of ship-radiated noise.The result shows its effectiveness and universality.

关键词： Complete ensemble empirical mode decomposition with adaptive noise Ship-radiated noise Feature extraction Classification and recognition

Enhancement of red upconversion emission intensity of Ho^(3+) ions in NaLuF4:Yb^(3+)/Ho^(3+)/Ce^(3+)@NaLuF_(4) core-shell nanoparticles

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Journal of Rare Earths 2022年第4期40卷 517-525,I0001页

作者： Wei Gao xiaotong Cheng Yu xing Shanshan Han Binhui Chen Qingyan Han Xuewen Yan Jihong Liu Lin Liu Jun Dong School of Electronic Engineering Xi'an University of Posts&TelecommunicationsXi'an 710121China

The red upconversion emission of Ho^(3+)ions,in the optical window of biological tissue,exhibits excellent prospects in biological applications.This study aims to enhance the red upconversion emission intensity of Ho^(3+)ions in NaLuF_(4):20%Yb^(3+)/2%Ho^(3+)/12%Ce^(3+) nanoparticles through building different core–shell structures with different excitation wavelengths.A significantly enhanced red upconversion emission with a higher red-to-green ratio was successfully obtained in NaLuF_(4):20%Yb^(3+)/2%Ho^(3+)/12%Ce^(3+)@NaLuF_(4) core–shell nanoparticles by introducing the Yb^(3+)and Yb^(3+)/Nd^(3+)ions into the NaLuF_(4) shell,with enhancement of the red emission occurring when Yb^(3+)and Nd^(3+)ions in the shell transfer more excitation energy to the Ho^(3+)ions.Investigation of the red emission enhancement mechanism is based on spectral characteristics and lifetimes.We examined the synergistic effect of dual-wavelength co-excitation NaLuF_(4):20%Yb^(3+)/2%Ho^(3+)/12%Ce^(3+)@NaLuF_(4):10%Yb^(3+)/15%Nd^(3+)core–shell nanoparticles to establish optimal excitation conditions.It is hoped that this method,using red upconversion emission core–shell nanoparticles with multi-mode excitation,can provide new ways to expand the applications of rare-earth luminescent materials in biomedicine and anti-counterfeiting.

关键词： NaLuF_(4)nanoparticles Upconversion Core-shell structure Energy transfer Dual-wavelength co-excitation Rare earths

TSR: algorithm of image hole-filling based on three-step repairing

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The Journal of China Universities of posts and telecommunications 2022年第5期29卷 83-91页

作者： Li Fucheng Deng Junyong Zhu Yun Luo Jiaying Ren Han School of Electronic Engineering Xi'an University of Posts and TelecommunicationsXi'an 710121China

In order to solve the hole-filling mismatch problem in virtual view synthesis, a three-step repairing(TSR) algorithm was proposed. Firstly, the image with marked holes is decomposed by the non-subsampled shear wave transform(NSST), which will generate high-/low-frequency sub-images with different resolutions. Then the improved Criminisi algorithm was used to repair the texture information in the high-frequency sub-images, while the improved curvature driven diffusion(CDD) algorithm was used to repair the low-frequency sub-images with the image structure information. Finally, the repaired parts of high-frequency and low-frequency sub-images are synthesized to obtain the final image through inverse NSST. Experiments show that the peak signal-to-noise ratio(PSNR) of the TSR algorithm is improved by an average of 2-3 dB and 1-2 dB compared with the Criminisi algorithm and the nearest neighbor interpolation(NNI) algorithm, respectively.

关键词： virtual view point synthesis hole-filling three-step repairing(TSR) Criminisi algorithm curvature driven diffusions(CDD)algorithm