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Frequency-comb-linearized, widely tunable lasers for coherent ranging

Photonics Research 2024年第4期12卷 663-681页

作者： BAOQI SHI YI-han LUO WEI SUN YUE HU jinbao LONG XUE BAI ANTING WANG JUNQIU LIU Department of Optics and Optical Engineering University of Science and Technology of ChinaHefei 230026China International Quantum Academy Shenzhen 518048China Shenzhen Institute for Quantum Science and Engineering Southern University of Science and TechnologyShenzhen 518055China Hefei National Laboratory University of Science and Technology of ChinaHefei 230088China

Tunable lasers,with the ability to continuously vary their emission wavelengths,have found widespread applications across various fields such as biomedical imaging,coherent ranging,optical communications,and spectroscopy.In these applications,a wide chirp range is advantageous for large spectral coverage and high frequency resolution.Besides,the frequency accuracy and precision also depend critically on the chirp linearity of the laser.While extensive efforts have been made on the development of many kinds of frequency-agile,widely tunable,narrow-linewidth lasers,wideband yet precise methods to characterize and linearize laser chirp dynamics are also demanded.Here we present an approach to characterize laser chirp dynamics using an optical frequency comb.The instantaneous laser frequency is tracked over terahertz bandwidth at 1 MHz intervals.Using this approach we calibrate the chirp performance of 12 tunable lasers from Toptica,Santec,New Focus,EXFO,and NKT that are commonly used in fiber optics and integrated photonics.In addition,with acquired knowledge of laser chirp dynamics,we demonstrate a simple frequency-linearization scheme that enables coherent ranging without any optical or electronic linearization unit.Our approach not only presents novel wideband,highresolution laser spectroscopy,but is also critical for sensing applications with ever-increasing requirements on performance.

关键词： tunable Focus coherent

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A wideband,high-resolution vector spectrum analyzer for integrated photonics

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Light(Science & Applications) 2024年第4期13卷 760-771页

作者： Yi-han Luo Baoqi Shi Wei Sun Ruiyang Chen Sanli Huang Zhongkai Wang jinbao Long Chen Shen Zhichao Ye Hairun Guo Junqiu Liu International Quantum Academy 518048 ShenzhenChina. Shenzhen Institute for Quantum Science and Engineering Southern University of Science and Technology518055 ShenzhenChina. Department of Optics and Optical Engineering University of Science and Technology of China230026 HefeiChina. Hefei National Laboratory University of Science and Technology of China230088 HefeiChina. Qaleido Photonics 518048 ShenzhenChina. Key Laboratory of Specialty Fiber Optics and Optical Access Networks Shanghai University200444 ShanghaiChina

The analysis of optical spectra—emission or absorption—has been arguably the most powerful approach for discovering and understanding matter.The invention and development of many kinds of spectrometers have equipped us with versatile yet ultra-sensitive diagnostic tools for trace gas detection,isotope analysis,and resolving hyperfine structures of atoms and molecules.With proliferating data and information,urgent and demanding requirements have been placed today on spectrum analysis with ever-increasing spectral bandwidth and frequency resolution.These requirements are especially stringent for broadband laser sources that carry massive information and for dispersive devices used in information processing systems.In addition,spectrum analyzers are expected to probe the device’s phase response where extra information is encoded.Here we demonstrate a novel vector spectrum analyzer(VSA)that is capable of characterizing passive devices and active laser sources in one setup.Such a dual-mode VSA can measure loss,phase response,and dispersion properties of passive devices.It also can coherently map a broadband laser spectrum into the RF domain.The VSA features a bandwidth of 55.1 THz(1260–1640 nm),a frequency resolution of 471 kHz,and a dynamic range of 56 dB.Meanwhile,our fiber-based VSA is compact and robust.It requires neither high-speed modulators and photodetectors nor any active feedback control.Finally,we employ our VSA for applications including characterization of integrated dispersive waveguides,mapping frequency comb spectra,and coherent light detection and ranging(LiDAR).Our VSA presents an innovative approach for device analysis and laser spectroscopy,and can play a critical role in future photonic systems and applications for sensing,communication,imaging,and quantum information processing.

关键词： spectrum resolution coherent

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Quick Weighing of Passing Vehicles Using the Transfer-Learning-Enhanced Convolutional Neural Network

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Computer Modeling in Engineering & Sciences 2024年第6期139卷 2507-2524页

作者： Wangchen Yan jinbao Yang Xin Luo College of Civil Engineering Xiangtan UniversityXiangtan411105China Energy&Environmental Engineering Department China CEC Engineering CorporationChangsha410114China

Transfer learning could reduce the time and resources required by the training of new models and be therefore important for generalized applications of the trainedmachine learning algorithms.In this study,a transfer learningenhanced convolutional neural network(CNN)was proposed to identify the gross weight and the axle weight of moving vehicles on the bridge.The proposed transfer learning-enhanced CNN model was expected to weigh different bridges based on a small amount of training datasets and provide high identification accuracy.First of all,a CNN algorithm for bridge weigh-in-motion(B-WIM)technology was proposed to identify the axle weight and the gross weight of the typical two-axle,three-axle,and five-axle vehicles as they crossed the bridge with different loading routes and speeds.Then,the pre-trained CNN model was transferred by fine-tuning to weigh themoving vehicle on another bridge.Finally,the identification accuracy and the amount of training data required were compared between the two CNN models.Results showed that the pre-trained CNN model using transfer learning for B-WIM technology could be successfully used for the identification of the axle weight and the gross weight for moving vehicles on another bridge while reducing the training data by 63%.Moreover,the recognition accuracy of the pre-trained CNN model using transfer learning was comparable to that of the original model,showing its promising potentials in the actual applications.

关键词： Bridge weigh-in-motion transfer learning convolutional neural network

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April-September minimum temperature reconstruction based on Sabina tibetica ring-width chronology in the central eastern Tibetan Plateau,China

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Journal of Forestry Research 2024年第2期35卷 134-145页

作者： Teng Li Jianfeng Peng Tsun Fung Au jinbao Li School of Geography and Remote Sensing Guangzhou UniversityGuangzhou 510006People’s Republic of China College of Geography and Environmental Science Henan UniversityKaifeng 475004People’s Republic of China Institute for Global Change Biology School for Environment and SustainabilityUniversity of MichiganAnn ArborMIUSA Department of Ecology and Evolutionary Biology University of MichiganAnn ArborMIUSA Department of Geography University of Hong KongHong Kong SARPeople’s Republic of China HKU Shenzhen Institute of Research and Innovation Shenzhen 518057People’s Republic of China

Minimum temperatures have remarkable impacts on tree growth at high-elevation sites on the Tibetan Plateau,but the shortage of long-term and high-resolution paleoclimate records inhibits understanding of recent minimum temperature anomalies.In this study,a warm season(April–September)reconstruction is presented for the past 467 years(1550–2016)based on Sabina tibetica ring-width chronology on the Lianbaoyeze Mountain of the central eastern Tibetan Plateau.Eight warm periods and eight cold periods were identified.Long-term minimum temperature variations revealed a high degree of coherence with nearby reconstructions.Spatial correlations between our reconstruction and global sea surface temperatures suggest that warm season minimum temperature anomalies in the central eastern Tibetan Plateau were strongly influenced by large-scale ocean atmospheric circulations,such as the El Ni?o-Southern Oscillation and the Atlantic Multidecadal Oscillation.

关键词： Tree-ring analysis Sabina tibetica Minimum temperatures Central eastern Tibetan Plateau Climate change

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Dendroclimatological study of Sabina saltuaria and Abies faxoniana in the mixed forests of the Qionglai Mountains,eastern Tibetan Plateau

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Journal of Forestry Research 2024年第1期35卷 72-82页

作者： Teng Li Jianfeng Peng Tsun Fung Au Jingru Li jinbao Li Yue Zhang School of Geography and Remote Sensing Guangzhou UniversityGuangzhou 510006People’s Republic of China College of Geography and Environmental Science Henan UniversityKaifeng 475004People’s Republic of China Institute for Global Change Biology School for Environment and SustainabilityUniversity of MichiganAnn ArborMIUSA Department of Ecology and Evolutionary Biology University of MichiganAnn ArborMIUSA Department of Geography University of Hong KongHong Kong SARPeople’s Republic of China HKU Shenzhen Institute of Research and Innovation Shenzhen 518057People’s Republic of China

Tree-ring chronologies were developed for Sabina saltuaria and Abies faxoniana in mixed forests in the Qionglai Mountains of the eastern Tibetan Plateau.Climate-growth relationship analysis indicated that the two co-exist-ing species reponded similarly to climate factors,although S.saltuaria was more sensitive than A.faxoniana.The strong-est correlation was between S.saltuaria chronology and regional mean temperatures from June to November.Based on this relationship,a regional mean temperature from June to November for the period 1605-2016 was constructed.Reconstruction explained 37.3%of the temperature variance during th period 1961-2016.Six major warm periods and five major cold periods were identified.Spectral analysis detected significant interannual and multi-decadal cycles.Reconstruction also revealed the influence of the Atlantic Multi-decadal Oscillation,confirming its importance on climate change on the eastern Tibetan Plateau.

关键词： Tree-ring analysis Mixed forests Dendroclimatology Qionglai Mountains

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Deep Industrial Image Anomaly Detection: A Survey

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Machine Intelligence Research 2024年第1期21卷 104-135页

作者： Jiaqi Liu Guoyang Xie jinbao Wang Shangnian Li Chengjie Wang Feng Zheng Yaochu Jin Research Institute of Trustworthy Autonomous Systems Southern University of Science and TechnologyShenzhen 518055China NICEGroup Universityof SurreyGuildford GU27YXUK Youtu Lab TencentShanghai 200233China NICE Group Bielefeld UniversityBielefeld 33619Germany

The recent rapid development of deep learning has laid a milestone in industrial image anomaly detection(IAD).In this pa-per,we provide a comprehensive review of deep learning-based image anomaly detection techniques,from the perspectives of neural net-work architectures,levels of supervision,loss functions,metrics and datasets.In addition,we extract the promising setting from indus-trial manufacturing and review the current IAD approaches under our proposed setting.Moreover,we highlight several opening chal-lenges for image anomaly detection.The merits and downsides of representative network architectures under varying supervision are discussed.Finally,we summarize the research findings and point out future research directions.More resources are available at https://***/M-3LAB/awesome-industrial-anomaly-detection.

关键词： Image anomaly detection defect detection industrial manufacturing deep learning computer vision

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Climate-growth relationships of Pinus tabuliformis along an altitudinal gradient on Baiyunshan Mountain,Central China

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Journal of Forestry Research 2024年第1期35卷 202-212页

作者： Xiaoxu Wei Jianfeng Peng jinbao Li Jinkuan Li Meng Peng Xuan Li Yameng Liu Jiaxin Li College of Geography and Environmental Science Henan UniversityKaifeng 475004People’s Republic of China Key Laboratory of Earth System Observation and Simulation of He’nan Province Kaifeng 475004People’s Republic of China Department of Geography University of Hong KongPokfulamHong Kong SARPeople’s Republic of China HKU Shenzhen Institute of Research and Innovation Shenzhen 518057People’s Republic of China

A set of standard chronologies for tree-ring width(TRW),earlywood width(EWW)and latewood width(LWW)in Pinus tabuliformis Carr.along an altitudi-nal gradient(1450,1400,and 1350 m a.s.l.)on Baiyunshan Mountain,Central China to analyze the effect of varying temperature and precipitation on growth along the gradi-ent.Correlation analyses showed that at all three altitudes and the TRW and EWW chronologies generally had signifi-cant negative correlations with mean and maximum tem-peratures in the current April and May and with minimum temperatures in the prior July and August,but significant positive correlations with precipitation in the current May.Correlations were generally significantly negative between LWW chronologies and all temperatures in the prior July and August,indicating that the prior summer temperature had a strong lag effect on the growth of P.tabuliformis that increased with altitude.The correlation with the standard-ized precipitation evapotranspiration index(SPEI)confirmed that wet conditions in the current May promoted growth of TR and EW at all altitudes.Significant altitudinal differences were also found;at 1400 m,there were significant positive correlations between EWW chronologies and SPEI in the current April and significant negative correlations between LWW chronologies and SPEI in the current September,but these correlations were not significant at 1450 m.At 1350 m,there were also significant negative correlations between the TRW and the EWW chronologies and SPEI in the prior October and the current July and between LWW chronology and SPEI in the current August,but these cor-relations were not significant at 1400 m.Moving correlation results showed a stable response of EWW in relation to the SPEI in the current May at all three altitudes and of LWW to maximum temperature in the prior July-August at 1400 m from 2002 to 2018.The EWW chronology at 1400 m and the LWW chronology at 1450 m were identified as more suitable for climate reconstruction.These results provide a strong scientific basis f

关键词： Tree rings Climate response Altitudinal gradient Baiyunshan Mountain Pinus tabuliformis Carr

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Microenvironmental effects on growth response of Pinus massoniana to climate at its northern boundary in the Tongbai Mountains,Central China

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Journal of Forestry Research 2024年第1期35卷 44-57页

作者： Jianfeng Peng Jiayue Cui jinbao Li Meng Peng Yongtao Ma Xiaoxu Wei Jinkuan Li Xuan Li Yamen Liu Jiaxin Li College of Geography and Environmental Science Henan UniversityKaifeng 475004People’s Republic of China Key Laboratory of Earth System Observation and Simulation of Henan Province Kaifeng 475004People’s Republic of China Department of Geography University of Hong KongHong KongSARPeople’s Republic of China HKU Shenzhen Institute of Research and Innovation Shenzhen 518057People’s Republic of China Henan Academy of Forestry Zhengzhou 450000People’s Republic of China

The Tongbai Mountains is an ecologically sensi-tive region and the northern boundary of Pinus massoniana Lamb.To analyze the effect of different microenvironments on tree growth response to climate factors,we developed standard chronologies for earlywood width(EWW),late-wood width(LWW),and total ring width(TRW)of P.massoniana at two sampling sites on slopes with different orientations,then analyzed characteristics of the chronolo-gies and their correlations with climate variables from five stations in the region and with a regional normalized differ-ence vegetation index(NDVI).Statistical results showed that the TRW/EWW/LWW chronology consistency and charac-teristics(mean sensitivity,signal to noise ratio,expressed population signal)for trees growing on the southeastern slope were much higher than for trees on the northeastern slope.Correlations indicated that temperature in current March and August has a significant positive effect on TRW/EWW/LWW formation,and the effect on the northeastern slope was weaker than on the southeastern slope.Compared to temperature,precipitation has more complicated effects on tree growth,but the effect on the northeastern slope was also generally weaker than on the southeastern slope.Step-wise linear regression analyses showed that temperature in August was the main limiting factor at the two sampling sites.Similarly,the response of tree growth on the southeast-ern slope as determined by the NDVI is better than on the northeastern slope,and the TRW/EWW/LWW chronologies for the southeastern slope explained over 50%of the total NDVI variances in June.Overall,the results indicate that the difference in the climate response of P.massoniana at two sampling sites is clearly caused by differences in the microenvironment,and such differences should be properly considered in future studies of forest dynamics and climate reconstructions.

关键词： Tree-rings Pinus massoniana lamb Microenvironment Radial growth Climate-growth response

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Flexible mille-feuille structure electromagnetic interference shielding film with excellent thermal conductivity and Joule heating

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Nano Research 2024年第5期17卷 4544-4554页

作者： Dingwen Yin Huijuan Xiu Simin Wang Yanfei Pan Na Li Rui Cheng Shaoyan Huang Sha Fan jinbao Li College of Bioresources Chemical&Materials Engineering Shaanxi University of Science&TechnologyXi'an 710021China National Demonstration Center for Experimental Light Chemistry Engineering Education Shaanxi Provincial Key Laboratory of Papermaking Technology and Specialty Paper DevelopmentXi'an 710021China College of Material Science and Art Design Inner Mongolia Agricultural UniversityHohhot 010018China

The intelligent electronic devices have urgent demands for electromagnetic interference(EMI)shielding films with excellent heat dissipation capability.However,it is challenging to obtain excellent EMI shielding and thermal conductivity performances simultaneously.Herein,inspired by mille-feuille structure,the multifunctional EMI shielding films developed by a layer-by-layer self-assembly and hot-pressing strategy.The ingenious introduction of silver nanoparticles(AgNPs)with large specific surface area and highly conductive into the network formed by TEMPO-oxidized cellulose nanofibrils(TOCNFs)with large aspect ratio to form the TOCNFs/AgNPs.And the graphene nanoplates(GNPs)with high conductivity loss distributed alternately with TOCNFs/AgNPs to construct mille-feuille structure,which had highly efficient conductive network,complete thermally conduction pathway and rich heterogeneous interfaces.Consequently,the designed films presented high electrical conductivity of 8520 S/cm,superb EMI effectiveness(SE)of 98.05 dB,and excellent thermal conductivity of 18.82 W/(m·K).Furthermore,the films possessed outstanding Joule heating performances with low voltages,including high heating temperature(100℃),fast response time(<20 s),and impressive heating stability and reliability.Thus,such high-performance EMI shielding films with fascinating thermal conductivity and Joule heating performances have substantial application in flexible electronics,electromagnetic waves shielding and thermal management.

关键词： TEMPO-oxidized cellulose nanofibrils/silver nanoparticles(TOCNFs/AgNPs) mille-feuille structure electromagnetic interference shielding thermal conductivity Joule heating

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Light-triggered fluorochromic cholesteric liquid crystal elastomer with hydrogen-bonded fluorescent switch: dualmodal-switchable circularly polarized luminescence

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Science China Chemistry 2024年第8期 2719-2727页

作者： Siyang Lin Tianqi Ren Xianyu Meng Wenxin Kang jinbao Guo Key Laboratory of Carbon Fibers and Functional Polymers Ministry of Education College of Materials Science and Engineering Beijing University of Chemical Technology

Solid materials with dynamically tunable circularly polarized luminescence（CPL） feature higher security levels and devicefriendly characteristics, showing great superiority in the field of information technology and anti-counterfeiting. To address the limited photoisomerization of fluorescent photoswitch in CPL-active solid materials, here a cholesteric liquid crystal elastomer（CLCE） containing a hydrogen-bonded（H-bonded） polymerizable fluorescent switch AHBA-PSD is prepared. Owing to the good flexibility and low glass-transition temperature of CLCE, AHBA-PSD shows a fast and fully reversible photocyclization/cycloreversion with fluorochromic behavior in CLCE. Further, by controlling the spectral overlapping area between the emission and reflection bands, the CLCE exhibits a strong CPL with a glumvalue of up to 0.76 accompanied by a reversible phototunable CPL signal. Meanwhile, the H-bond helps to stabilize the mechanical property, and the force-induced switching-off of CPL signal could be achieved due to the destroyed helical structures by external force. Finally, an automatically-recognized identification card with abundant chiroptical information is demonstrated.

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