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Enhanced Grain Refining Effect of Mg–Zr Master Alloy on Magnesium Alloys via a Synergistic Strategy Involving Heterogeneous Nucleation and Solute‑Driven Growth Restriction

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Acta Metallurgica Sinica(English Letters) 2024年第8期37卷 1354-1366页

作者： Gang zeng Hong Liu Jing‑Peng Xiong Jian‑Long Li Yong Liu Key Laboratory of Lightweight and High Strength Structural Materials of Jiangxi Province School of Advanced ManufacturingNanchang UniversityNanchang 330031China

Zirconium(Zr)emerges as the most effective grain refiner for magnesium(Mg)alloys incorporating ***,Zr is introduced in the form of an Mg–Zr master ***,within Mg–Zr master alloys,Zr predominantly exists in a particle form,which tends to aggregate due to attractive van der Waals *** clustered Zr is prone to settling,thereby reducing its refining impact on Mg *** this work,a combined pretreatment process for Mg–Zr master alloys was proposed,encompassing the introduction of a physical field to intervene the agglomeration of particle Zr and the employ of high-temperature dissolution and peritectic reactions to promote the solid solution of *** results demonstrate that the particle Zr within the pretreated Mg–Zr master alloy is effectively dispersed and refined,and greater solute Zr levels can be *** subsequent grain refinement ability was studied on a typical Mg–6Zn–0.6Zr(wt%)*** outcome highlights that an improvement in the grain refinement efficacy(32.4%)of Mg–Zr master alloys was obtained with a holding time of 60 *** pretreated Mg–Zr master alloy significantly augments the efficiency of grain refinement for Mg alloys through a synergistic strategy involving heterogeneous nucleation and solute-driven growth *** crucial factor in achieving effective grain refinement of Zr in Mg alloys lies in regulating the presence and morphology of Zr in the Mg–Zr master alloy,distinguishing between particle Zr and solute *** study introduces a novel method for developing more efficient Mg–Zr refiners.

关键词： Magnesium alloy Mg-Zr master alloy Grain refinement Heterogeneous nucleation Solute-driven growth restriction Synergistic strategy

Advances in environmental DNA monitoring:standardization,automation,and emerging technologies in aquatic ecosystems

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Science China(Life Sciences) 2024年第7期67卷 1368-1384页

作者： Suxiang Lu Honghui zeng Fan Xiong Meng Yao Shunping He State Key Laboratory of Freshwater Ecology and Biotechnology Institute of HydrobiologyChinese Academy of SciencesWuhan 430072China Institute of Ecology College of Urban and Environmental SciencesPeking UniversityBeijing 100871China School of Life Sciences Peking UniversityBeijing 100871China Institute of Deep Sea Science and Engineering Chinese Academy of SciencesSanyaChina Center for Excellence in Animal Evolution and Genetics Chinese Academy of SciencesKunmingChina

Environmental DNA(eDNA)monitoring,a rapidly advancing technique for assessing biodiversity and ecosystem health,offers a noninvasive approach for detecting and quantifying species from various environmental *** this review,a comprehensive overview of current eDNA collection and detection technologies is provided,emphasizing the necessity for standardization and automation in aquatic ecological ***,the intricacies of water bodies,from streams to the deep sea,and the associated challenges they pose for eDNA capture and analysis are *** paper delineates three primary eDNA survey methods,namely,bringing back water,bringing back filters,and bringing back data,each with specific advantages and constraints in terms of labor,transport,and data ***,innovations in eDNA sampling equipment,including autonomous drones,subsurface samplers,and in-situ filtration devices,and their applications in monitoring diverse taxa are ***,recent advancements in species-specific detection and eDNA metabarcoding are addressed,highlighting the integration of novel techniques such as CRISPR-Cas and nanopore sequencing that enable precise and rapid detection of *** implications of environmental RNA and epigenetic modifications are considered for future applications in providing nuanced ecological ***,the review stresses the critical role of standardization and automation in enhancing data consistency and comparability for robust long-term *** propose that the amalgamation of these technologies represents a paradigm shift in ecological monitoring,aligning with the urgent call for biodiversity conservation and sustainable management of aquatic ecosystems.

关键词： eDNA methodology sampler environment biomonitoring ecogenomic sensors ocean observation instrument

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Enabling the transfer matrix method to model serial-parallel compliant mechanisms including curved flexure beams

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International Journal of Mechanical System Dynamics 2024年第1期4卷 48-62页

作者： Mingxiang Ling Lei Yuan Tingjun zeng Xianmin Zhang Robotics and Microsystems Center Soochow UniversitySoochowChina Guangdong Key Laboratory of Precision Equipment and Manufacturing Technology School of Mechanical and Automotive EngineeringSouth China University of TechnologyGuangzhouChina

Compliant mechanisms with curved flexure hinges/beams have potential advantages of small spaces,low stress levels,and flexible design parameters,which have attracted considerable attention in precision engineering,metamaterials,robotics,and so ***,serial-parallel configurations with curved flexure hinges/beams often lead to a complicated parametric ***,the transfer matrix method is enabled for analysis of both the kinetostatics and dynamics of general serial-parallel compliant mechanisms without deriving laborious formulas or combining other modeling ***,serial-parallel compliant mechanisms with curved flexure hinges/beams can be modeled in a straightforward manner based on a single transfer matrix of Timoshenko straight beams using a step-by-step *** and numerical validations on two customized XY nanopositioners comprised of straight and corrugated flexure units confirm the concise modeling process and high prediction accuracy of the presented *** conclusion,the present study provides an enhanced transfer matrix modeling approach to streamline the kinetostatic and dynamic analyses of general serial-parallel compliant mechanisms and beam structures,including curved flexure hinges and irregular-shaped rigid bodies.

关键词： compliant mechanisms curved flexure beams transfer matrix method nanopositioner rigid-body dynamics

Achieving full mutualism with massive passive devices for multiuser MIMO symbiotic radio

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Science China(Information Sciences) 2024年第9期67卷 196-212页

作者： Jingran XU Zhuoyin DAI Yong zeng Shi JIN Tao JIANG National Mobile Communications Research Laboratory Southeast University Purple Mountain Laboratories Research Center of 6G Mobile Communications School of Cyber Science and Engineering and Wuhan National Laboratory for Optoelectronics Huazhong University of Science and Technology

Symbiotic radio(SR) is one of the attractive communication technologies to facilitate largescale Internet of Things(IoT) connections with enhanced energy and spectrum efficiency, where passive backscatter devices(BDs) modulate their information over the radio frequency(RF) signals emitted by the active primary transmitters(PTs). Meanwhile, the primary transmission can be strengthened with the additional multipaths created by BDs. To capitalize to a greater extent on the mutualism relationship between the two types of communication, this paper studies multiple-input multiple-output(MIMO) SR communication systems including multiple PTs and massive BDs. We derive the achievable rate expressions of each PT and BD, as well as the sum rate expressions of primary and secondary communication, *** asymptotic analysis is given to derive the active and passive communication rates with a large number of BDs. Furthermore, for the general case with a finite number of BDs, we study the precoding optimization problem to maximize the sum rate of primary communication, while ensuring that the sum rate of secondary communication and the individual rate for each PT and BD in the prescribed active and passive user sets satisfy the specified thresholds. Simulation results are presented to verify the analytical studies.

关键词： multiuser MIMO SR backscattering massive backscatter devices asymptotic analysis active and passive communication

High-performance self-powered GaN/PEDOT:PSS hybrid heterojunction UV photodetector for optical communication

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Science China(Technological Sciences) 2024年第2期67卷 608-615页

作者： LI Shan LIU zeng ZHANG MaoLin YANG LiLi GUO YuFeng TANG WeiHua College of Integrated Circuit Science and Engineering&National and Local Joint Engineering Laboratory for RF Integration and Micro-Packing Technologies Nanjing University of Posts and TelecommunicationsNanjing 210023China

Self-powered ultraviolet photodetectors(UVPDs)provide great possibility for the next-generation energy conservation optical communication technology;while the high photodetection performance at zero bias is still a tremendous ***,ntype GaN film with Si-doping concentration of~1018cm^(-3)and p-type organic PEDOT:PSS were adopted to construct a planar hybrid heterojunction via the simple spin-coating *** from typical type-Ⅱenergy band alignment and giant photovoltaic effect at GaN/PEDOT:PSS inorganic-organic interface,the fabricated UVPD achieved excellent self-powered photoelectrical properties in dual-band with large R of 0.96 A/W(2.8 A/W),superior D*of 5.7×1012Jones(1.7×10^(13)Jones),prominent EQE of 325%(1371%),high on/off ratio of 9.65×10^(3)(6.15×10^(3))and fast rise/decay time of 60.7/124.5 ms(30.9/26.7 ms)for UVA(UVC)band,as well as outstanding UV/visible rejection ratio and great detection *** as an optical signal receiver,this designed self-powered UVPD decoded a message of“NJUPT”from a simple optical communication *** results open a new avenue for GaN/PEDOT:PSS heterojunction in UV communications and related applications.

关键词： GaN UV photodetector self-powered heterojunction optical communication

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The source of Double ITCZ induced by the SST bias over the tropical western Pacific as reflected in CAS-ESM2 Model

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Science China Earth Sciences 2024年第5期67卷 1604-1615页

作者： Jinning TONG Fei ZHENG Jiangbo JIN Ruowen YANG Jiang ZHU Qingcun zeng Department of Atmospheric Sciences Yunnan UniversityKunming 650091China International Center for Climate and Environment Science Institute of Atmospheric PhysicsChinese Academy of SciencesBeijing 100029China

“Double ITCZ”is a common precipitation bias over the tropical Pacific in current climate models and Earth system models,but the reasons for its formation are still worth exploring and *** this study,we adopted the second version of Chinese Academy of Sciences Earth System Model(CAS-ESM2),by comparing a set of sea surface temperature(SST)bias correction experiments over the tropical Pacific,to explore the possible mechanism of SST bias on inducing the“Double ITCZ”from the perspective of the climatic annual mean bias in the coupled *** revealed that the simulated climatic annual mean SST bias over the tropical Pacific can affect the bias of latent heat flux through the saturation specific humidity,and the bias of latent heat flux can further affect that of vertical velocity of humid air by the condensation release mechanism,and finally modulate the simulated bias in ***,through the inter-comparison between different experiments,it is found that the source of Double ITCZ might mainly come from the annual mean SST bias over the tropical western Pacific through the proposed air-sea coupled process of“SST-saturated specific humidity-latent heat flux-vertical velocity-precipitation”,indicating a possible way on reducing the couple biases in models over the tropical Pacific to improve the accuracy of CAS-ESM2 for climate simulation.

关键词： SST bias Double ITCZ Nudging SST CAS-ESM2

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Deep Broad Learning for Emotion Classification in Textual Conversations

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Tsinghua Science and Technology 2024年第2期29卷 481-491页

作者： Sancheng Peng Rong zeng Hongzhan Liu Lihong Cao Guojun Wang Jianguo Xie Center for Linguistics and Applied Linguistics and Laboratory of Language Engineering and ComputingGuangdong University of Foreign StudiesGuangzhou 510006China Guangdong Provincial Key Laboratory of Nanophotonic Functional Materials and Devices South China Normal UniversityGuangzhou 510006China School of Computer Science and Cyber Engineering Guangzhou UniversityGuangzhou 510006China Modern Education Technology Center Guangdong University of Foreign StudiesGuangzhou 510006China

Emotion classification in textual conversations focuses on classifying the emotion of each utterance from textual *** is becoming one of the most important tasks for natural language processing in recent ***,it is a challenging task for machines to conduct emotion classification in textual conversations because emotions rely heavily on textual *** address the challenge,we propose a method to classify emotion in textual conversations,by integrating the advantages of deep learning and broad learning,namely *** aims to provide a more effective solution to capture local contextual information(i.e.,utterance-level)in an utterance,as well as global contextual information(i.e.,speaker-level)in a conversation,based on Convolutional Neural Network(CNN),Bidirectional Long Short-Term Memory(Bi-LSTM),and broad *** experiments have been conducted on three public textual conversation datasets,which show that the context in both utterance-level and speaker-level is consistently beneficial to the performance of emotion *** addition,the results show that our proposed method outperforms the baseline methods on most of the testing datasets in weighted-average F1.

关键词： emotion classification textual conversation Convolutional Neural Network(CNN) Bidirectional Long Short-Term Memory(Bi-LSTM) broad learning

Modelling and simulation study on dynamic pollution accumulation process of composite insulator

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High Voltage 2024年第3期9卷 601-613页

作者： Zhongyi Yang Dongxiong Liu Xiangjun zeng Caijin Fan Xin Yang Yafei Huang School of Electrical and Information Engineering Changsha University of Science and TechnologyChangshaChina State Key Laboratory of HVDC Electric Power Research InstituteCSGGuangzhouChina

With the widespread application of composite insulators in transmission lines,exploring the accumulation mechanism of pollution particles on composite insulator surfaces is of importance to ensure the safe and steady operation of the power *** the current theoretical shortcomings,this study categorises the accumulation process of particles on the insulator surface into three stages,namely‘spatial motion’,‘surface collision’,and‘surface motion’.The motion and rotation velocities in a multi-physics field are calculated in the spatial motion *** the surface collision stage,a parameter called‘neck height’is introduced to determine the optimum mechanics theory,and the normal deposition criterion is *** the surface motion stage,the sliding displacement and rolling displacement on the surface are calculated based on the rotation speed of the particles.A dynamic pollution accumulation model of the composite insulator is estab-lished based on the normal deposition criterion and tangential ***,numerical simulations are performed by using the finite element *** results show that the proposed model agrees with the actual insulator pollution accu-mulation,and the deposition model is still applicable for various types of composite insulators operating in different applied *** deposition probability of particles increases with the increasing particle *** the surface motion stage,particle displacement increases with particle size and wind velocity.

关键词： composite displacement dynamic

Efficient oxidation of monosaccharides to sugar acids under neutral condition in flow reactors with gold-supported activated carbon catalysts

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Frontiers of Chemical Science and Engineering 2024年第9期18卷 113-123页

作者： Ziqin Gong zengyong Li Xu zeng Fengxia Yue Wu Lan Chuanfu Liu State Key Laboratory of Pulp and Paper Engineering School of Light Industry&EngineeringSouth China University of TechnologyGuangzhou 510640China Anhui Provincial Engineering Center for High Performance Biobased Nylons School of Materials and ChemistryAnhui Agricultural UniversityHefei 230036China

A significant reaction in the synthesis of biomass-based chemicals is the catalyst-based and targeted oxidation of monosaccharides into valuable sugar *** this study,an activated carbon supported gold catalyst was used to oxidize glucose and xylose to gluconic acid and xylonic acid under neutral *** of reaction conditions for the catalysts was performed using both a batch reactor and a flow-through *** a batch reactor,the yields of gluconic and xylonic acid reached 93%and 92%,respectively,at 90°C within 180 *** a flow reactor,both reactions reached a similar yield at 80°C with the weight hourly space velocity of 47.1 h^(-1).The reaction kinetics were explored in the flow *** oxidation of glucose and xylose to gluconic and xylonic acid followed a first-order kinetics and the turnover frequency was 0.195 and 0.161 s^(-1),*** activation energy was evaluated to be 60.58 and 59.30 kJ·mol^(-1),*** study presents an environmentally friendly and feasible method for the selective oxidation of monosaccharides using an activated carbon supported gold catalyst,benefiting the high-value application of carbohydrates.

关键词： monosaccharides oxidation gluconic acid xylonic acid flow reactor kinetics