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Vortex excites unidirectional water waves near ancient Luoyang Bridge

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Frontiers of physics 2024年第3期19卷 163-165页

作者： Yichen Li xinhua Hu Department of Materials Science and Key Laboratory of Micro-and Nano-Photonic Structures(Ministry of Education) Fudan UniversityShanghai 200433China

Since the discovery of generalized Snell’s law in 2011[1],metasurfaces have opened up the mainstream of arbitrary wavefront manipulation in *** a gradient-index metasurface,the parallel wavenumber kx of reflected wave can be not equal to the incident one(kx=ξ+k0sinθi,where k0 andθi are the incident wavenumber and angle,andξis the phase gradient of metasurface in its supercell)[1].Whenξ>k0,the reflected wave becomes a surface wave bounded on the metasurface(where|kx|>k0,kz is imaginary,and z is normal to the metasurface)[2].However,as research of metasurfaces continually evolves,some articles have pointed out that such graded metasurfaces suffer from a series of problems[3-6].In particular,multiple metallic resonators are adopted in a subwavelength supercell,resulting in impedance mismatch,moderate conversion efficiency,wave absorption,and fabrication ***,although the approach of graded metasurfaces has been demonstrated in the microwave regime,it is hard to extend to infrared and optical ranges with shorter *** solve this problem,Ra’di et al.[7]devised metagratings with periodic arrays of bianisotropic scatterers and showed that they enable wave front engineering with unitary efficiency and significantly lower fabrication demands.

关键词： graded reflected imaginary

Cr-containing wastewater treatment based on Cr self-catalysis: a critical review

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Frontiers of Environmental Science & Engineering 2024年第1期18卷 1-22页

作者： Manshu Zhao xinhua Wang Shuguang Wang Mingming Gao School of Environmental Science and Engineering Shandong UniversityQingdao 266237China Shandong Key Laboratory of Environmental Processes and Health Shandong UniversityQingdao 266237China Shandong Key Laboratory of Water Pollution Control and Resource Reuse Shandong UniversityQingdao 266237China Weihai Research Institute of Industrial Technology of Shandong University Weihai 264209China

Chromium (Cr), as a transition metal material with multiple redox states, has exhibited the catalysis toward Fenton-like reactions over a wide pH range. Although it is not sensible to add Cr reagents as catalysts due to its toxicity, it is highly promising to remediate Cr-containing wastewater through Cr-initiated advanced oxidation processes (Cr-initiated AOPs), which are clean and low-cost. Moreover, the widely concerned Cr-complexes, considered as obstacles in the remediation process, can be effectively destroyed by AOPs. Cr self-catalysis is defined as Cr species is both substrate and catalyst. However, the full understanding of Cr self-catalysis, including the generation of intermediates Cr(IV)/Cr(V), the synergetic effects with co-existing ions, and the accumulation of toxic Cr(VI), remains a challenge for the practical application of Cr-initiated AOPs. In this review, relevant researches on Cr self-catalysis during Cr-initiated AOPs are summarized. Specifically, the Cr-Fenton-like reaction, Cr substituted materials, and Cr-sulfite reactions are explored as key mechanisms contributing to Cr self-catalysis. Moreover, Cr transformation processes, including synchronously Cr removal, Cr redox reactions, and Cr(VI) accumulation, in AOPs-based synergistic systems are systematically analyzed. Detailed approaches for the detection of active species in AOPs-based systems are also presented. The primary objective of this review is to explore the application of AOPs for Cr-containing wastewater remediation based on Cr self-catalysis, and provide fundamental insights and valuable information for future research on Cr-initiated AOPs.

关键词： Self-catalysis Cr-initiated AOPs Cr transformation Cr intermediates Cr-containing wastewater

Low-cost portable dielectric spectrometer based on mini-vector network analyzer and open-ended coaxial probe technology

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International Journal of Agricultural and Biological Engineering 2024年第3期17卷 166-172页

作者： Zhuozhuo Zhu xinhua Zhu Wenchuan Guo College of Mechanical and Electronic Engineering Northwest A&F UniversityYangling 712100ShaanxiChina School of Physics and Electronic Information Yan'an UniversityYan'an 716000ShaanxiChina Shaanxi Research Center of Agricultural Equipment Engineering Technology Yangling 712100ShaanxiChina Key Laboratory of Agricultural Internet of Things Ministry of Agriculture and Rural AffairsYangling 712100ShaanxiChina Shaanxi Key Laboratory of Agricultural Information Perception and Intelligent Service Yangling 712100ShaanxiChina

As a simple,fast,and non-destructive measuring technology,dielectric spectroscopy is usually used to analyze the dielectric properties of agricultural products and food,and then to predict the main components of ***,the large and expensive vector network analyzers(VNA)with expensive analysis software applied in measuring dielectric properties make research limited to the *** acquire dielectric spectra in situ,a model for solving relative complex permittivity was derived,and its performance was ***,a low-cost portable dielectric spectrometer with a mini VNA,a Raspberry Pi,and a coaxial probe as core parts was developed over the frequency range of 100-3000 *** stability and accuracy of the developed spectrometer were tested using milk and *** results indicated that the relative errors of the model were within±5%for dielectric constant(ε′)and loss factor(ε″).The coefficients of variation of measuredε′andε″by the developed spectrometer at 100-3000 MHz were less than 1%and 2%,*** with the dielectric properties obtained by using a commercial dielectric measurement system,the relative errors of measuredε′andε″were within±3.4%and±6.0%,*** study makes fast,non-destructive,and on-site food quality detection using dielectric spectra possible.

关键词： coaxial probe mini vector network analyzer low-cost portable dielectric spectrometer

NHC-derived carbon-centered luminescent radicals with shortwavelength emission via suppression of Kasha's rule

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Science China Chemistry 2024年第8期67卷 2679-2685页

作者： Can Chen Xin Li xinhua Ouyang Ying-Feng Han Key Laboratory of Synthetic and Natural Functional Molecule Chemistry of the Ministry of Education Xi’an Key Laboratory of Functional Supramolecular Structure and MaterialsCollege of Chemistry and Materials ScienceNorthwest UniversityXi’an 710127China College of Material Engineering Fujian Agriculture and Forestry University Fuzhou 350108China

Luminescent organic radicals have garnered increasing attention owing to their versatile applications in sensing, imaging, and organic light-emitting diodes(OLEDs), attributed to their unique emission properties originating from the doublet spin ***, the natural narrow bandgap of organic free radicals typically limits their emission to the long-wavelength *** luminescent organic radicals with short-wavelength emission remains a significant challenge. Herein, a series of carbon-centered radicals with short-wavelength emission(383–476 nm) by combining N-heterocyclic carbenes with various polycyclic aromatic hydrocarbons(PAHs)(2-naphthyl, 2a~Ⅰ and 2b~Ⅰ;2-phenanthryl, 2a~Ⅱand 2b~Ⅱ;2-anthryl, 2a~Ⅲand 2b~Ⅲ;3-phenanthryl, 2a~Ⅳand 2b~Ⅳ). Theoretical calculations reveal that the introduction of PAHs significantly increases the ΔE_(D2-D1) in 2a^(Ⅰ–Ⅲ)and 2b^(Ⅰ–Ⅲ)compared to that in phenyl-derived radical congeners. Consequently, the internal transition from D2 to D1 is impeded, leading to a high yield of D2 emission and a suppressed Kasha's rule, thereby overcoming the limitations imposed by their narrow bandgap. For 2a~Ⅳ and 2b~Ⅳ, despite a moderately large ΔED2-D1value, the ΔED3-D1value exceeds 1 e V, indicating that their emission likely originates from the D3 state. Furthermore, we utilized 2a~Ⅲand 2b~Ⅲ as emissive materials in OLEDs,resulting in blue emissions with external quantum efficiencies of 7.5% and 6.5%, respectively.

关键词： N-heterocyclic carbenes luminescent organic molecules carbon-centered radicals short-wavelength emission

Exercise Fatigue Monitoring Based on R-Peak Detection Using UNET-TCN

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Journal of Beijing Institute of Technology 2024年第4期33卷 337-345页

作者： xinhua Su Xuxuan Wang Xinxin Ma Schoolof Sports Engineering Beijing Sport UniversityBeijing100091China

Moderate exercise contributes to health, but excessive exercise may lead to physicalinjury or even endanger life. It is pressing for a device that can detect the intensity of ***, in order to enable real-time detection of exercise intensity and mitigate the risks of harmfrom excessive exercise, a exercise intensity monitoring system based on the heart rate variability(HRV) from electrocardiogram (ECG) signal and linear features from phonocardiogram (PCG)signal is proposed. The main contributions include: First, accurate analysis of HRV is crucial forsubsequent exercise intensity detection. To enhance HRV analysis, we propose an R-peak detectorbased on encoder-decoder and temporal convolutional network (TCN). Experimental resultsdemonstrate that the proposed R-peak detector achieves an F1 score exceeding 0.99 on real high-intensity exercise ECG datasets. Second, an exercise fatigue monitoring system based on multi-sig-nal feature fusion is proposed. Initially, utilizing the proposed R-peak detector for HRV extractionin exercise intensity detection,which outperforms traditional algorithms, with the system achiev-ing a classification performance of 0.933 sensitivity, 0.802 specificity, and 0.960 accuracy. To fur-ther improve the system, we combine HRV with the linear features of PCG. Our exercise intensitydetection system achieves 90.2% specificity, 96.7% recall, and 98.1% accuracy in five-fold cross-vali-dation.

关键词： heart rate variability(HRV) phonocardiogram(PCG) Unet temporal convolutionalnetwork(TCN) machine learning exercise intensity

PCG-Based Exercise Fatigue Detection Method Using FRFT-Based Fusion Model

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Journal of Beijing Institute of Technology 2024年第4期33卷 298-306页

作者： Xinxin Ma xinhua Su Huanmin Ge Schoolof Sports Engineering Beijing Sport UniversityBeijing 100084China.

Accurate detection of exercise fatigue based on physiological signals is vital for reason-able physical *** a non-invasive technology,phonocardiogram(PCG)signals possess arobust capability to reflect cardiovascular information,and their data acquisition devices are *** this study,a novel hybrid approach of fractional Fourier transform(FRFT)com-bined with linear and discrete wavelet transform(DWT)features extracted from PCG is proposedfor PCG multi-class *** proposed system enhances the fatigue detection performanceby combining optimized FRFT features with an effective aggregation of linear features and *** FRFT technique is employed to convert the 1-D PCG signal into 2-D image which issent to a pre-trained convolutional neural network structure,called *** features from theVGG-16 were concatenated with the linear and DWT features to form fused *** fusedfeatures are sent to support vector machine(SVM)to distinguish six distinct fatigue ***-mental results demonstrate that the proposed fused features outperform other feature combinationssignificantly.

关键词： exercise fatigue phonocardiogram(PCG) fractional Fourier transform(FRFT) dis-crete wavelet transform(DWT) future fusion

Light People: Professor Fanglin Bao and his cover story

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Light(Science & Applications) 2024年第6期13卷 1015-1020页

作者： ji Wang School of Science Westlake UniversityHangzhouZhejiangPR China

Qu Yuan,a renowned ancient Chinese poet,once pondered in his work Heavenly Inquiry:“If the sun’s light is absent,from where does the radiance of the Hero Flower emanate?”The ability to see clearly in the darkest of nights has long been a sought-after magical power by *** holds not only immense technological significance for computer vision and remote sensing but also profound implications for transcending the dichotomy between day and night in our daily *** Fanglin Bao from Westlake University has made significant breakthroughs in this field,bringing us closer to a world where we can transform night into *** groundbreaking research on Heat-Assisted Detection and Ranging(HADAR)and night vision was featured as the cover story in Nature on July 26,2023.

关键词： bringing breakthrough holds

Multimode Design and Analysis of an Integrated Leg-Arm Quadruped Robot with Deployable Characteristics

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Chinese Journal of Mechanical Engineering 2024年第3期37卷 41-61页

作者： Fuqun Zhao Yifan Wu xinhua Yang Xilun Ding Kun Xu Sheng Guo Xiaodong jin School of Mechanical Engineering and Automation Beihang UniversityBeijing 100191China School of Mechanical Electronic and Control EngineeringBeijing Jiaotong UniversityBeijing 100044China

To improve locomotion and operation integration, this paper presents an integrated leg-arm quadruped robot(ILQR) that has a reconfigurable joint. First, the reconfigurable joint is designed and assembled at the end of the legarm chain. When the robot performs a task, reconfigurable configuration and mode switching can be achieved using this joint. In contrast from traditional quadruped robots, this robot can stack in a designated area to optimize the occupied volume in a nonworking state. Kinematics modeling and dynamics modeling are established to evaluate the mechanical properties for multiple modes. All working modes of the robot are classified, which can be defined as deployable mode, locomotion mode and operation mode. Based on the stability margin and mechanical modeling, switching analysis and evaluation between each mode is carried out. Finally, the prototype experimental results verify the function realization and switching stability of multimode and provide a design method to integrate and perform multimode for quadruped robots with deployable characteristics.

关键词： Quadruped robot Multimode design Mode switching Locomotion Operation

Application of deep learning for informatics aided design of electrode materials in metal-ion batteries

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Green Energy & Environment 2024年第5期9卷 877-889页

作者： Bin Ma Lisheng Zhang Wentao Wang Hanqing Yu Xianbin Yang Siyan Chen Huizhi Wang xinhua Liu School of Transportation Science and Engineering Beihang UniversityBeijing102206China College of Automotive Engineering Jilin UniversityChangchun130022China Department of Mechanical Engineering Imperial College LondonLondonSW72BXUK

To develop emerging electrode materials and improve the performances of batteries,the machine learning techniques can provide insights to discover,design and develop battery new materials in high-throughput *** this paper,two deep learning models are developed and trained with two feature groups extracted from the Materials Project datasets to predict the battery electrochemical performances including average voltage,speciﬁc capacity and speciﬁc *** deep learning models are trained with the multilayer perceptron as the *** Bayesian optimization and Monte Carlo methods are applied to improve the prediction accuracy of *** on 10 types of ion batteries,the correlation coefﬁcients are maintained above 0.9 compared to DFT calculation results and the mean absolute error of the prediction results for voltages of two models can reach 0.41 V and 0.20 V,*** electrochemical performance prediction times for the two trained models on thousands of batteries are only 72.9 ms and 75.7 ***,the two deep learning models are applied to approach the screening of emerging electrode materials for sodium-ion and potassium-ion *** work can contribute to a high-throughput computational method to accelerate the rational and fast materials discovery and design.

关键词： Cathode materials Material design Electrochemical performance prediction Deep learning Metal-ion batteries