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Tree species classification in an extensive forest area using airborne hyperspectral data under varying light conditions

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Journal of Forestry Research 2023年第5期34卷 1359-1377页

作者： Wen jia Yong Pang Institute of Forest Resource Information Techniques Chinese Academy of ForestryBeijing 100091People’s Republic of China Key Laboratory of Forestry Remote Sensing and Information System National Forestry and Grassland AdministrationBeijing 100091People’s Republic of China

Although airborne hyperspectral data with detailed spatial and spectral information has demonstrated significant potential for tree species classification,it has not been widely used over large areas.A comprehensive process based on multi-flightline airborne hyperspectral data is lacking over large,forested areas influenced by both the effects of bidirectional reflectance distribution function(BRDF)and cloud shadow *** this study,hyperspectral data were collected over the Mengjiagang Forest Farm in Northeast China in the summer of 2017 using the Chinese Academy of Forestry's LiDAR,CCD,and hyperspectral systems(CAF-LiCHy).After BRDF correction and cloud shadow detection processing,a tree species classification workflow was developed for sunlit and cloud-shaded forest areas with input features of minimum noise fraction reduced bands,spectral vegetation indices,and texture *** indicate that BRDF-corrected sunlit hyperspectral data can provide a stable and high classification accuracy based on representative training ***-shaded pixels also have good spectral separability for species *** red-edge spectral information and ratio-based spectral indices with high importance scores are recommended as input features for species classification under varying light *** to the classification accuracies through field survey data at multiple spatial scales,it was found that species classification within an extensive forest area using airborne hyperspectral data under various illuminations can be successfully carried out using the effective radiometric consistency process and feature selection strategy.

关键词： Tree species classification BRDF effects Cloud shadow Airborne hyperspectral data Random forest

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Modeling of Multipath Channel and Performance Analysis of MIMO-DCO-OFDM System in Visible Light Communications

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Chinese Journal of Electronics 2019年第3期28卷 630-639页

作者： jia Kejun HAO Li Key Laboratory of Information Coding and Transmission Southwest Jiaotong University School of Computer and Communication Lanzhou University of Technology

When a big path difference exists between the multiple transmitter-receiver links, time dispersion is inevitable. A multipath channel model is proposed for Multiple-input multiple-output(MIMO)Visible light communications(VLC). To combat Intersymbol interference(ISI) as well as increase the channel capacity, a combination of MIMO and Direct-currentbiased Optical orthogonal frequency division multiplexing(DCO-OFDM) is studied. The performance analysis of MIMO-DCO-OFDM taking into account the limitation of the forward current of the off-the-shelf LED is *** accuracy of the theoretical results is verified by comparison with the Monte Carlo Bit error ratio(BER)simulation results under different DC bias and different clipping levels.

关键词： Visible light communication(VLC) Multiple input multiple output(MIMO) DC-biased optical OFDM Multipath channel model Clipping noise

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Facile synthesis of transition metal complexes with five coplanar metal-carbon σ-bonds

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National Science Review 2024年第4期11卷 11-12页

作者： Guocheng jia Department of Chemistry Hong Kong University of Science and Technology

Carbon is one of the most important elements in chemistry, forming a vast number of organic compounds. It can also form a variety of organometallic compounds with a metal–carbon bond. Metal alkyl, carbene and carbyne complexes are classical examples of organometallic compounds. A particularly interesting class of organometallic compounds are all-carbon metallacycles formed by combination of a metal and a hydrocarbon chain serving as a chelating agent with only carbon atoms as the donor atoms. Many interesting monocyclic metallacycles made of a chelating bidentate hydrocarbon chain are known, for example, metallacyclobutadienes, metallacyclopentadienes and metallabenzenes[1].

关键词： with bonds complexes coplanar facile five metal-carbon synthesis transition

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Random stability for lateral vibration on footbridge based on IEVIE-PDE method

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Earthquake Engineering and Engineering Vibration 2021年第4期20卷 981-992页

作者： jia Buyu Yu Xiaolin School of Civil Engineering and Transportation South China University of TechnologyGuangzhou 510640China Newmark Structural Engineering Laboratory University of Illinois at Urbana-ChampaignUrbana 61801USA

The pedestrian-induced lateral vibration of footbridges is essentially classified as a nonlinear stochastic ***,bridge vibration stability falls within the field of nonlinear stochastic vibration *** present,the Lyapunov method is mainly used to analyze such ***,this method is qualitative,and it cannot quantitatively analyze the vibration stability *** this study,a new analytical method based on a comparison of the input energy and the variation of intrinsic energy(IEVIE)is used to analyze the nonlinear stochastic vibration stability of the lateral vibration of the *** improved Nakamura model is used to describe the lateral nonlinear stochastic vibration of the footbridge.A combination of the IEVIE method and the probability density evolution(PDE)method is then proposed,in which the IEVIE method is utilized to determine vibration *** PDE method is used to obtain the reliability of vibration *** proposed method is successfully applied to the Millennium Bridge,and its effectiveness is verified by comparing the Monte Carlo and Lyapunov *** proposed method can obtain the dynamic probability of the vibration as stable or instable and provide a reference for quantitative analysis of lateral nonlinear stochastic vibration stability of footbridges.

关键词： footbridge lateral vibration stochastic stability quantitative

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The Module-Phase Synchronization of Complex-Valued Neural Networks with Time-Varying Delay and Stochastic Perturbations

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Journal of Systems Science & Complexity 2021年第6期34卷 2139-2154页

作者： NIAN Fuzhong LI jia School of Computer Sz Communication Lanzhou University of TechnologyLanzhou 730050China

The problem of exponential module-phase synchronization of complex-valued neural networks(CVNNs)with time-varying delay and stochastic perturbations was *** model of CVNNs with time-varying delay and stochastic perturbations was *** error system was deduced and the module-phase synchronization was *** on the principle of Lyapunov stability theory,the appropriate controller was designed to control the ***,the effectiveness and reliability of the method were verified by the numerical simulations.

关键词： Complex-valued neural networks exponential module-phase synchronization Lyapunov function time-varying delay

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Yi Zeng:promoting good governance of artificial intelligence

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National Science Review 2020年第12期7卷 1954-1956页

作者： Hepeng jia Science Communication at Soochow University and a freelancing science writer for NSR

Artificial intelligence (AI) has developed quickly in recent years,with applications expanding from automatic driving and smart manufacturing to personal healthcare and algorithm-based social media *** the COVID-19 pandemic,AI has played an essential role in identifying suspected infections,ensuring epidemic surveillance and quickening drug ***,many questions accompanied AI’s *** to protect citizens’ privacy and national information security?

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Data-driven short circuit resistance estimation in battery safety issues

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Journal of Energy Chemistry 2023年第4期79卷 37-44页

作者： Yikai jia Jun Xu Department of Mechanical Engineering and Engineering Science The University of North Carolina at CharlotteCharlotteNC 28223USA Vehicle Energy&Safety Laboratory(VESL) North Carolina Battery ComplexityAutonomous Vehicle and Electrification(BATT CAVE)Research CenterThe University of North Carolina at CharlotteCharlotteNC 28223USA School of Data Science The University of North Carolina at CharlotteCharlotteNC 28223USA

Developing precise and fast methods for short circuit detection is crucial for preventing or mitigating the risk of safety issues of lithium-ion batteries(LIBs).In this paper,we developed a Convolutional Neural Networks(CNN)based model that can quickly and precisely predict the short circuit resistance of LIB cells during various working *** tests of cells with an external short circuit(ESC)are produced to obtain the database and generate the training/testing *** samples are sequences of voltage,current,charging capacity,charging energy,total charging capacity,total charging energy with a length of 120 s and frequency of 1 Hz,and their corresponding short circuit resistances.A big database with~6×10^(5)samples are generated,covering various short circuit resistances(47~470Ω),current loading modes(Constant current-constant voltage(CC-CV)and drive cycle),and electrochemical states(cycle numbers from 1 to 300).Results show that the average relative absolute error of five random sample splits is 6.75%±2.8%.Further parametric analysis indicates the accuracy estimation benefits from the appropriate model setups:the optimized input sequence length(~120 s),feature selection(at least one total capacity-related variable),and rational model design,using multiple layers with different kernel *** work highlights the capabilities of machine learning algorithms and data-driven methodologies in real-time safety risk prediction for batteries.

关键词： Lithium-ion battery Safety risk Internal short circuit Short circuit resistance Convolutional neural networks

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A novel strategy for fine-grained semantic verification of civil aviation radiotelephony read-backs

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Chinese Journal of Aeronautics 2022年第12期35卷 266-277页

作者： Guimin jia Junxian LI Tianjin Key Lab for Advanced Signal Processing Civil Aviation University of ChinaTianjin 300300China College of Electronic Information and Automation Civil Aviation University of ChinaTianjin 300300China

During the flight of the aircraft,the pilot must repeat the instruction sent by the controller,and the controller must further confirm these read-backs,in this way to further ensure the safety of air ***,fatigue,tension,negligence and other human factors may prevent the controller from realizing read-back errors in time,which is a huge hidden danger for the safety of civil aviation *** paper proposes a novel strategy to implement fine-grained semantic verification of radiotelephony read-backs by introducing interaction layer and attention mechanism at the output of BiLSTM *** with the traditional twochannel verification strategy,the interaction layer is added to obtain fine-grained semantic matching relation representation,rather than connecting the BiLSTM output vectors to obtain the overall semantic representation of the *** by adding attention layer,the new strategy can capture the potential semantic relation between the read-backs and the instructions,which is applicable to non-standard diction and abbreviated read-backs in real radiotelephony *** experiments are conducted and the results show that the proposed new strategy is more effective than the traditional method for read-backs checking,and the average test accuracy of the new strategy based on the Chinese ATC radiotelephony read-backs corpus can reach 93.03%.

关键词： Attention mechanism BiLSTM Interaction layer Radiotelephony read-backs Semantic verification

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The VCOs in ISSCC 2023 set the new performance frontier of silicon-based oscillators

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Journal of Semiconductors 2023年第5期44卷 7-8页

作者： Haikun jia Institute of Mircoelectronics Tsinghua University100084China

High-quality frequency generators are one of the fundamental building blocks in high-throughput wireless communication *** by the fast-growing demand for high data rate communications,the signal generator continues to be an active research *** have been dedicated to improving the performance,including but not limited to phase noise,frequency tuning range,power consumption.

关键词： ISSCC tuning wireless

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Simple primitive recognition via hierarchical face clustering

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Computational Visual Media 2020年第4期6卷 431-443页

作者： Xiaolong Yang Xiaohong jia Academy of Mathematics and Systems Science Chinese Academy of SciencesBeijing 100190China University of Chinese Academy of Sciences Beijing 100049China

We present a simple yet efficient algorithm for recognizing simple quadric primitives(plane,sphere,cylinder,cone)from triangular *** approach is an improved version of a previous hierarchical clustering algorithm,which performs pairwise clustering of triangle patches from bottom to *** key contributions of our approach include a strategy for priority and fidelity consideration of the detected primitives,and a scheme for boundary smoothness between adjacent *** results demonstrate that the proposed method produces qualitatively and quantitatively better results than representative state-of-the-art methods on a wide range of test data.

关键词： quadric primitive extraction mesh hierarchical clustering

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