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Plasmon-induced nonlinear response on gold nanoclusters

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Chinese Physics B 2024年第4期33卷 36-39页

作者：宋玉慧曹逸飞黄思晨李凯超杜如海严蕾付正坤张正龙 School of Physics and Information Technology Shaanxi Normal UniversityXi'an 710119China

The plasmon-induced nonlinear response has attracted great attention in micro-nano optics and optoelectronics applications,yet the underlying microscopic mechanism remains *** this study,the nonlinear response of gold nanoclusters when exposed to a femtosecond laser pulse was investigated using time-dependent density functional *** was observed that the third-order tunneling current was augmented in plasmonic dimers,owing to a greater number of electrons in the dimer being excited from occupied to unoccupied *** findings provide profound theoretical insights and enable the realization of accurate regulation and control of nonlinear effects induced by plasmons at the atomic level.

关键词： plasmon nonlinear optics time-dependent density functional theory(TDDFT)

Self‐suspended rare‐earth doped up‐conversion luminescent waveguide:propagating and directional radiation

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Opto-Electronic Advances 2020年第6期3卷 1-7,I0001页

作者： Changjian Zhang Chengyun Zhang Zhenglong Zhang Tao He Xiaohu Mi Ting Kong zhengkun fu Hairong Zheng Hongxing Xu School of Physics and Information Technology Shaanxi Normal UniversityXi’an 710062China School of Physics and Technology Wuhan UniversityWuhan 430072China

Near-infrared excited rare-earth(RE)-doped up-conversion(UC)-luminescent materials have attracted enormous attention because of their unique emission properties,such as narrow emission bands,long luminescence lifetimes,and multiple ***,current development of RE-doped luminescent material is hindered by weak and narrowband absorption problems and low photon-conversion quantum *** addition to conventional approaches to enhance fluorescence intensity,controlling emission directivity to improve detection efficiency has become a promising approach to obtain higher luminescence *** this paper,a self-suspended RE-doped UC luminescent waveguide is designed to realize directional *** from the special morphology of the crown-like NaYF4:Yb3+/Er3+microparticle,the points contact between the waveguide and substrate can be obtained to decrease energy *** attractive UC luminescent pattern accompanied by powerful and controllable directional emissions is observed,and the spatial emission angle and intensity distribution are explored and analyzed in detail by introducing Fourier imaging detection and *** work provides a new method for achieving controllable directional fluorescence emissions and obtaining improved detection efficiency by narrowing emission directivity,which has potential applications in 3-dimensional displays and micro-optoelectronic devices,especially when fabricating self-fluorescence micron lasers.

关键词： rare-earth-doped microcrystal up-conversion self-suspended Fourier imaging

A Tutorial on Quantized Feedback Control

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IEEE/CAA Journal of Automatica Sinica 2024年第1期11卷 5-17页

作者： Minyue fu IEEE the School of System Design and Intelligent Manufacturing Shenzhen Key Laboratory of Control Theory and Intelligent Systems and Centre for Control Science and TechnologySouthern University of Science and TechnologyShenzhen 518055China

In this tutorial paper, we explore the field of quantized feedback control, which has gained significant attention due to the growing prevalence of networked control systems. These systems require the transmission of feedback information, such as measurements and control signals, over digital networks, presenting novel challenges in estimation and control design. Our examination encompasses various topics, including the minimal information needed for effective feedback control, the design of quantizers, strategies for quantized control design and estimation,achieving consensus control with quantized data, and the pursuit of high-precision tracking using quantized measurements.

关键词： Consensus control high-precision control networked control quantized estimation quantized feedback control robust control

Coupling Coordination Analysis of Cropland Intensification and Agroecosystem Services:Evidence from Loess Plateau in Shaanxi Province,China

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Chinese Geographical Science 2024年第3期34卷 401-419页

作者： fu Shaowu fu Mengyu QIU Menglong Center for Land Resource Research in Northwest China Shaanxi Normal UniversityXi’an 710119China

One of the greatest challenges in the agroecosystem is to improve cropland intensification while preserving agroecosystem *** many studies have investigated the effect of cropland intensification on agroecosystem service,the interactive coupling and coordination among these factors remain largely *** view of this,this study performed a case study of the Loess Plateau in Shaanxi Province,China and constructed comprehensive evaluation models to quantify the cropland intensification and agroecosystem service in this *** analysis and the coupling coordination degree model were used to evaluate the interactive relationship between cropland intensification and agroecosystem service,and statistical analysis and spatial autocorrelation were used to analyze the spatial characteristics and potential mechanism of the coupling *** show that both the cropland intensification and agroecosystem service in the study area were relatively low yet gradually increased from 2000 to *** service lag was identified as the dominant unbalanced development *** the supply capacity of agroecosystem services plays a key role in the balanced development of cropland in the Loess *** coupling coordination degree between cropland intensification and agroecosystem service ranges from basic coordination to serious ***,cropland intensification practices in the area should be optimized to enhance this coordination *** upward trend was also observed in the coupling coordination degree from2000 to *** withdrawal of marginal cropland in the Grain for Green program is one of the most important reasons for this trend,especially for the northern *** 83.6%of the high-high clusters are concentrated in the southern region of the Loess Plateau,whereas 70.5%of the low-low clusters are distributed in the northern *** clustering characteristics are mainly attributed to the environmental

关键词： cropland intensification agroecosystem services balance analysis coupling coordination degree Loess Plateau,China

Dynamics of 2×2 matrix non-Hermitian quantum systems on Bloch sphere

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Communications in Theoretical Physics 2024年第4期76卷 66-71页

作者： Libin fu Graduate School of China Academy of Engineering Physics Beijing 100193China

By casting evolution to the Bloch sphere, the dynamics of 2 × 2 matrix non-Hermitian systems are investigated in detail. This investigation reveals that there are four kinds of dynamical modes for such systems. The different modes are classified by different kinds of fixed points, namely,the elliptic point, spiral point, critical node, and degenerate point. The Hermitian systems and the unbroken PT non-Hermitian cases belong to the category with elliptic points. The degenerate point just corresponds to the systems with exceptional point(EP). The topological properties of the fixed point are also discussed. It is interesting that the topological charge for the degenerate point is two, while the others are one.

关键词： non-Hermitian quantum system two-level system dynamics on the Bloch sphere PT-symmetry fixed points

New speckle pattern interferometry for precise in situ deformation measurements

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Chinese Optics Letters 2024年第1期22卷 34-40页

作者：章如月 Yu fu 缪泓 CAS Key Laboratory of Mechanical Behavior and Design of Materials Department of Modern MechanicsUniversity of Science and Technology of ChinaHefei 230027China Shenzhen Key Laboratory of Intelligent Optical Measurement and Detection College of Physics and Optoelectronic EngineeringShenzhen UniversityShenzhen 518060China

A new electronic speckle pattern interferometry method is proposed to realize in situ deformation *** feature of the method is the combination of a high-speed camera and multiple laser Doppler vibrometers(LDVs)for synchronous *** high-speed camera is used to record and select effective interferograms,while the LDVs are used to measure the rigid body displacement caused by vibrations.A series of effective interferograms with known shifted phase values are obtained to calculate the deformation *** experimental results show that the method performs well in measuring static and dynamic deformations with high accuracy in vibrating environments.

关键词： speckle pattern interferometry laser Doppler vibrometers in situ deformation measurements

Small Cycles Property of Some Cremer Rational Maps and Polynomials

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Chinese Annals of Mathematics,Series B 2024年第1期45卷 123-136页

作者： Rong fu Ji ZHOU Faculty of Science Yibin UniversityYibin 644000SichuanChina Department of Mathematical Sciences Sichuan Normal UniversityChengdu 610066China

This paper concerns the linearization problem on rational maps of degree d≥2 and polynomials of degree d>2 from the perspective of *** authors introduce a set l_(∞) of irrational numbers and show that if α∈l_(∞),then any rational map is not linearizable and has infinitely many cycles in every neighborhood of the fixed point with multiplier λ=e^(2πiα),Adding more constraints to cubic polynomials,they discuss the above problems by polynomial-like *** the family of polynomials,with the help of Yoccoz's method,they obtain its maximum dimension of the set in which the polynomials are non-linearizable.

关键词： Irrationally indifferent fixed point Linearization problem Small cycles property

A stochastic gradient-based two-step sparse identification algorithm for multivariate ARX systems

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Control Theory and Technology 2024年第2期22卷 213-221页

作者： Yanxin fu Wenxiao Zhao Key Laboratory of Systems and Control Academy of Mathematics and Systems ScienceChinese Academy of SciencesBeijing100190China School of Mathematical Sciences University of Chinese Academy of SciencesBeijing100049China

We consider the sparse identification of multivariate ARX systems, i.e., to recover the zero elements of the unknown parameter matrix. We propose a two-step algorithm, where in the first step the stochastic gradient (SG) algorithm is applied to obtain initial estimates of the unknown parameter matrix and in the second step an optimization criterion is introduced for the sparse identification of multivariate ARX systems. Under mild conditions, we prove that by minimizing the criterion function, the zero elements of the unknown parameter matrix can be recovered with a finite number of observations. The performance of the algorithm is testified through a simulation example.

关键词： ARX system Stochastic gradient algorithm Sparse identification Support recovery Parameter estimation Strong consistency

Floating Waste Discovery by Request via Object-Centric Learning

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Computers, Materials & Continua 2024年第7期80卷 1407-1424页

作者： Bingfei fu School of Computer Science Fudan UniversityShanghai200438China

Discovering floating wastes,especially bottles on water,is a crucial research problem in environmental ***,real-world applications often face challenges such as interference from irrelevant objects and the high cost associated with data ***,devising algorithms capable of accurately localizing specific objects within a scene in scenarios where annotated data is limited remains a formidable *** solve this problem,this paper proposes an object discovery by request problem setting and a corresponding algorithmic *** proposed problem setting aims to identify specified objects in scenes,and the associated algorithmic framework comprises pseudo data generation and object discovery by request ***-data generation generates images resembling natural scenes through various data augmentation rules,using a small number of object samples and scene *** network structure of object discovery by request utilizes the pre-trained Vision Transformer(ViT)model as the backbone,employs object-centric methods to learn the latent representations of foreground objects,and applies patch-level reconstruction constraints to the *** the validation phase,we use the generated pseudo datasets as training sets and evaluate the performance of our model on the original test *** have proved that our method achieves state-of-the-art performance on Unmanned Aerial Vehicles-Bottle Detection(UAV-BD)dataset and self-constructed dataset Bottle,especially in multi-object scenarios.

关键词： Unsupervised object discovery object-centric learning pseudo data generation real-world object discovery by request