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China Ocean Engineering 2024年第2期38卷 285-296页

作者： DU Zun-feng ZHU Hai-ming YU jian-xing State Key Laboratory of Hydraulic Engineering Intelligent Construction and Operation School of Civil EngineeringTianjin UniversityTianjin 300350China

When investigating the vortex-induced vibration(VIV)of marine risers,extrapolating the dynamic response on the entire length based on limited sensor measurements is a crucial step in both laboratory experiments and fatigue monitoring of real *** problem is conventionally solved using the modal decomposition method,based on the principle that the response can be approximated by a weighted sum of limited vibration ***,the method is not valid when the problem is underdetermined,i.e.,the number of unknown mode weights is more than the number of known *** study proposed a sparse modal decomposition method based on the compressed sensing theory and the Compressive Sampling Matching Pursuit(Co Sa MP)algorithm,exploiting the sparsity of VIV in the modal *** the validation study based on high-order VIV experiment data,the proposed method successfully reconstructed the response using only seven acceleration measurements when the conventional methods failed.A primary advantage of the proposed method is that it offers a completely data-driven approach for the underdetermined VIV reconstruction problem,which is more favorable than existing model-dependent solutions for many practical applications such as riser structural health monitoring.

关键词： motion reconstruction vortex-induced vibration(VIV) marine riser modal decomposition method compressed sensing

Vertical two-dimensional WS_(2)flakes grown on flexible CNT film for excellent electrochemical performance

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Rare Metals 2024年第1期43卷 164-174页

作者： Qian Gong Jing-Yun Zou ming Ren Si-Qi Zhu Yu-Rong Zhou Li-ming Zhao jian Chen Yu-Long Wu jiang-Tao Di Li-Xing Kang Qing-Wen Li School of Nano-Tech and Nano-Bionics University of Science and Technology of ChinaHefei 230026China Key Laboratory of Multifunctional Nanomaterials and Smart Systems Division of Advanced MaterialsSuzhou Institute of Nano-Tech and Nano-BionicsChinese Academy of SciencesSuzhou 215123China jiangsu Key Laboratory of Micro and Nano Heat Fluid Flow Technology and Energy Application School of Physical Science and TechnologySuzhou University of Science and TechnologySuzhou 215009China

Soft electrochemical actuators that can generate mechanical motions in response to electrical stimuli can be used as artificial muscles in microscale *** electrode materials are the key component of the electrochemical actuator because they limit the ion diffusion and accumulation processes and thus affect the deformation in fast response-time and potential engineering ***-dimensional materials,such as one-dimensional(1D)CNT and two-dimensional(2D)vertically stood WS_(2),are great electrode due to their good electrochemical stability and high surface-to-volume ratios,but show limited performances when being used on their own in the actuators because of low reconstruction or low conductivity.A combination of 1D CNT and 2D WS_(2)could form a heterojunction with both high electrochemical activity and great mechanical ***,by depositing highly disordered graphene nanosheets(HDGNs)on CNT films and then WS_(2)on the formed low-dimensional nanocarbon film,a hybrid WS_(2)/HDGN/CNT film was synthesized through a multistep CVD *** grown WS_(2)nanosheets were achieved by taking advantage of HDGNs which limits CNTs ***,the volume expansion caused by the transition from WO_(3)to WS-2can force the vertical growth of WS_(2).This hybrid film shows excellent electrochemical properties,such as high specific capacitance and high rate *** actuators based on the WS_(2)/HDGN/CNT films show good actuating performance,including stability and reconfigurability.

关键词： CNT Graphene Vertically growth WS_(2) Electrochemical actuators

Assessment of Wet Season Precipitation in the Central United States by the Regional Climate Simulation of the WRFG Member in NARCCAP and Its Relationship with Large-Scale Circulation Biases

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Advances in Atmospheric Sciences 2024年第4期41卷 619-638页

作者： Yating ZHAO ming XUE Jing jiang Xiao-ming HU Anning HUANG School of Atmospheric Sciences Nanjing UniversityNanjing 210023China Center for Analysis and Prediction of Storms and School of Meteorology The University of OklahomaNorman 73072U.S.A

Assessment of past-climate simulations of regional climate models(RCMs)is important for understanding the reliability of RCMs when used to project future regional ***,we assess the performance and discuss possible causes of biases in a WRF-based RCM with a grid spacing of 50 km,named WRFG,from the North American Regional Climate Change Assessment Program(NARCCAP)in simulating wet season precipitation over the Central United States for a period when observational data are *** RCM reproduces key features of the precipitation distribution characteristics during late spring to early summer,although it tends to underestimate the magnitude of *** dry bias is partially due to the model’s lack of skill in simulating nocturnal precipitation related to the lack of eastward propagating convective systems in the *** in reproducing large-scale circulation and environmental conditions is another contributing *** too weak simulated pressure gradient between the Rocky Mountains and the Gulf of Mexico results in weaker southerly winds in between,leading to a reduction of warm moist air transport from the Gulf to the Central Great *** simulated low-level horizontal convergence fields are less favorable for upward motion than in the NARR and hence,for the development of moist convection as ***,a careful examination of an RCM’s deficiencies and the identification of the source of errors are important when using the RCM to project precipitation changes in future climate scenarios.

关键词： NARCCAP Central United States precipitation low-level jet large-scale environment diurnal variation

Synergistic integration of self-supported 1T/2H-WS_(2) and nitrogendoped rGO on carbon cloth for pH-universal electrocatalytic hydrogen evolution

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Nano Research 2024年第3期17卷 1267-1280页

作者： Feng ming Yap jian Yiing Loh Wee-Jun Ong School of Energy and Chemical Engineering Xiamen University MalaysiaSelangor Darul Ehsan 43900Malaysia Center of Excellence for NaNo Energy&Catalysis Technology(CONNECT) Xiamen University MalaysiaSelangor Darul Ehsan 43900Malaysia State Key Laboratory of Physical Chemistry of Solid Surfaces College of Chemistry and Chemical EngineeringXiamen UniversityXiamen 361005China Gulei Innovation Institute Xiamen UniversityZhangzhou 363200China Shenzhen Research Institute of Xiamen University Shenzhen 518057China

Hydrogen economy based on electrochemical water splitting exemplified one of the most promising means for overcoming the rapid consumption of fossil fuels and the serious deterioration of global *** development of earth-abundant,efficient,and durable electrocatalysts for hydrogen evolution reaction(HER)plays a vital role in the commercialization of water ***,the self-supported electrode with unique nitrogen-doped reduced graphene oxide(N-rGO)nanoflakes and WS_(2) hierarchical nanoflower that were grown directly on carbon cloth(CC)substrate(WS_(2)/N-rGO/CC)was successfully synthesized using a facile dual-step hydrothermal *** as-synthesized 50%1T/2H-WS_(2)/N-rGO/CC(WGC),which possessed high metallic 1T phase of 57%not only efficiently exposed more active sites and accelerated mass/charge diffusion,but also endowed excellent structural lustiness,robust stability,and durability at a high current *** a result,the 50%WGC exhibited lower overpotentials and Tafel slopes of 21.13 mV(29.55 mV∙dec^(-1))and 80.35 mV(137.02 mV∙dec^(-1))as compared to 20%Pt-C/CC,respectively for catalyzing acidic and alkaline hydrogen evolution ***,the as-synthesized 50%WGC also depicted long-term stability for more than 8 h in the high-current-density regions(100 and 220 mA∙cm^(-2)).In brief,this work reveals a self-supported electrode as an extraordinary alternative to Pt-based catalysts for HER in a wide pH range,while paving a facile strategy to develop advanced electrocatalysts with abundant heterointerfaces for practical applications in energy-saving hydrogen production.

关键词： self-supported electrocatalyst carbon-based substrate phase engineering pH-universal water splitting

Could natural phytochemicals be used to reduce nitrogen excretion and excreta‑derived N_(2)O emissions from ruminants?

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Journal of Animal Science and Biotechnology 2024年第2期15卷 490-508页

作者： Yuchao Zhao ming Liu Linshu jiang Leluo Guan Beijing Key Laboratory of Dairy Cow Nutrition College of Animal Science and TechnologyBeijing University of AgricultureBeijing 102206China College of Animal Science and Technology China Agricultural UniversityBeijing 100193China Department of Agricultural Food and Nutritional ScienceUniversity of AlbertaEdmontonAB T6G 2R3Canada

Ruminants play a critical role in our food system by converting plant biomass that humans cannot or choose not to consume into edible high-quality ***,ruminant excreta is a significant source of nitrous oxide(N_(2)O),a potent greenhouse gas with a long-term global warming potential 298 times that of carbon *** phytochemicals or forages containing phytochemicals have shown the potential to improve the efficiency of nitrogen(N)utilization and decrease N_(2)O emissions from the excreta of *** inclusion of tannins can shift more of the excreted N to the feces,alter the urinary N composition and consequently reduce N_(2)O emissions from *** oils or saponins could inhibit rumen ammonia production and decrease urinary N *** grazed pastures,large amounts of glucosinolates or aucubin can be introduced into pasture soils when animals consume plants rich in these compounds and then excrete them or their metabolites in the urine or *** inhibitory compounds are excreted in the urine,they would be directly applied to the urine patch to reduce nitrification and subsequent N_(2)O *** phytochemicals’role in sustainable ruminant production is undeniable,but much uncertainty ***,transient effects,and adverse effects limit the effectiveness of these phytochemicals for reducing N *** this review,we will identify some current phytochemicals found in feed that have the potential to manipulate ruminant N excretion or mitigate N_(2)O production and deliberate the challenges and opportunities associated with using phytochemicals or forages rich in phytochemicals as dietary strategies for reducing N excretion and excreta-derived N_(2)O emissions.

关键词： Nitrogen metabolism Nitrous oxide Plant bioactive compounds Ruminant Urine patches

Relaxed Stability Criteria for Time-Delay Systems:A Novel Quadratic Function Convex Approximation Approach

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IEEE/CAA Journal of Automatica Sinica 2024年第4期11卷 996-1006页

作者： Shenquan Wang Wenchengyu Ji Yulian jiang Yanzheng Zhu jian Sun College of Electrical and Electronic Engineering Changchun University of TechnologyChangchun 130012China the College of Electrical Engineering and Automation Shandong University of Science and TechnologyQingdao 266590China Key Laboratory of Complex Systems Intelligent Control and Decision Beijing Institute of TechnologyBeijing 100081China

This paper develops a quadratic function convex approximation approach to deal with the negative definite problem of the quadratic function induced by stability analysis of linear systems with time-varying *** introducing two adjustable parameters and two free variables,a novel convex function greater than or equal to the quadratic function is constructed,regardless of the sign of the coefficient in the quadratic *** developed lemma can also be degenerated into the existing quadratic function negative-determination(QFND)lemma and relaxed QFND lemma respectively,by setting two adjustable parameters and two free variables as some particular ***,for a linear system with time-varying delays,a relaxed stability criterion is established via our developed lemma,together with the quivalent reciprocal combination technique and the Bessel-Legendre *** a result,the conservatism can be reduced via the proposed approach in the context of constructing Lyapunov-Krasovskii functionals for the stability analysis of linear time-varying delay ***,the superiority of our results is illustrated through three numerical examples.

关键词： Equivalent reciprocal combination technique quadratic function convex approximation approach stability timevarying delay

Echo State Network Based on Improved Knowledge Distillation for Edge Intelligence

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Chinese Journal of Electronics 2024年第1期33卷 101-111页

作者： jian ZHOU Yuwen jiang Lijie XU Lu ZHAO Fu XIAO College of Computer Nanjing University of Posts and Telecommunications jiangsu High Technology Research Key Laboratory for Wireless Sensor Networks

Echo state network(ESN) as a novel artificial neural network has drawn much attention from time series prediction in edge intelligence. ESN is slightly insufficient in long-term memory, thereby impacting the prediction performance. It suffers from a higher computational overhead when deploying on edge devices. We firstly introduce the knowledge distillation into the reservoir structure optimization, and then propose the echo state network based on improved knowledge distillation(ESN-IKD) for edge intelligence to improve the prediction performance and reduce the computational overhead. The model of ESN-IKD is constructed with the classic ESN as a student network, the long and short-term memory network as a teacher network, and the ESN with double loop reservoir structure as an assistant network. The student network learns the long-term memory capability of the teacher network with the help of the assistant network. The training algorithm of ESN-IKD is proposed to correct the learning direction through the assistant network and eliminate the redundant knowledge through the iterative pruning. It can solve the problems of error learning and redundant learning in the traditional knowledge distillation process. Extensive experimental simulation shows that ESN-IKD has a good time series prediction performance in both long-term and short-term memory, and achieves a lower computational overhead.

关键词： Knowledge engineering Training Performance evaluation Computational modeling Time series analysis Artificial neural networks Reservoirs

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MXene Key Composites:A New Arena for Gas Sensors

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Nano-Micro Letters 2024年第10期16卷 350-391页

作者： Yitong Wang Yuhua Wang Min jian Qinting jiang Xifei Li Hubei Province Key Laboratory of Systems Science in Metallurgical Process Wuhan University of Science and TechnologyWuhan 430081People's Republic of China Key Materials and Components of Electrical Vehicles for Overseas Expertise Introduction Center for Discipline Innovation Institute of Advanced Electrochemical Energy and School of Materials Science and EngineeringXi'an University of TechnologyXi'an 710048People's Republic of China College of Materials Science and Engineering Fuzhou UniversityFuzhou 350108FujianPeople's Republic of China

With the development of science and technology,the scale of industrial production continues to grow,and the types and quantities of gas raw materials used in industrial production and produced during the production process are also constantly *** gases include flammable and explosive gases,and even contain toxic ***,it is very important and necessary for gas sensors to detect and monitor these gases quickly and *** recent years,a new two-dimensional material called MXene has attracted widespread attention in various *** abundant surface functional groups and sites,excellent current conductivity,tunable surface chemistry,and outstanding stability make them promising for gas sensor *** the birth of MXene materials,researchers have utilized the efficient and convenient solution etching preparation,high flexibility,and easily functionalize MXene with other materials to pre-pare composites for gas *** has opened a new chapter in high-performance gas sensing materials and provided a new approach for advanced sensor ***,previous reviews on MXene-based composite materials in gas sensing only focused on the performance of gas sensing,without systematically explaining the gas sensing mechanisms generated by different gases,as well as summarizing and predicting the advantages and disadvantages of MXene-based composite *** article reviews the latest progress in the application of MXene-based composite materials in gas ***,a brief summary was given of the commonly used methods for preparing gas sens-ing device structures,followed by an introduction to the key attributes of MXene related to gas sensing *** article focuses on the performance of MXene-based composite materials used for gas sensing,such as MXene/graphene,MXene/Metal oxide,MXene/Transition metal sulfides(TMDs),MXene/Metal-organic framework(MOF),MXene/*** summarizes the advantages and disad

关键词： MXene Compound material Gas sensor Gas sensitive preparation Gas sensitivity performance

Global Spherically Symmetric Solutions for a Coupled Compressible Navier–Stokes/Allen–Cahn System

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Acta Mathematica Sinica,English Series 2024年第8期40卷 2037-2064页

作者： Chang ming SONG jian Lin ZHANG Yuan Yuan WANG Department of Applied Mathematics School of Mathematics and Information ScienceZhongyuan University of TechnologyZhengzhou 450007P.R.China

In this paper,we consider the global spherically symmetric solutions for the initial boundary value problem of a coupled compressible Navier–Stokes/Allen–Cahn system which describes the motion of two-phase viscous compressible *** prove the existence and uniqueness of global classical solution,weak solution and strong solution under the assumption of spherically symmetry condition for initial dataρ0 without vacuum state.

关键词： Diffuse interface model global solutions Navier-Stokes equations Allen-Cahn equation spherically symmetry

Impact of cooling rate on exfoliation corrosion resistance of a Li-containing 7xxx aluminum alloy

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Journal of Central South University 2024年第7期31卷 2225-2236页

作者： jiang Ke-da LIAO Ze-xin CHEN ming-yang LIU Sheng-dan TANG jian-guo School of Materials Science and Engineering Central South UniversityChangsha 410083China National Key Laboratory of Science and Technology on High-strength Structural Materials Central South UniversityChangsha 410083China Key Laboratory of Non-ferrous Metals Materials Science and Engineering Ministry of EducationCentral South UniversityChangsha 410083China

The impact of cooling rate after solution heat treatment on exfoliation corrosion resistance of a Li-containing 7xxx aluminum alloy was investigated by accelerated immersion and electrochemical impedance spectroscopy test,optical microscope,electron backscatter diffraction and scanning transmission electron *** the decrease of cooling rate from 1700℃/s to 4℃/s,exfoliation corrosion resistance of the aged specimens decreases with rating changing from EA to EC and the maximum corrosion depth increasing from about 169.4μm to 632.1μ*** corrosion tends to develop along grain boundaries in the specimens with cooling rates higher than about 31℃/s and along both grain boundaries and sub-grain boundaries in the specimens with lower cooling *** reason has been discussed based on the changes of the microstructure and microchemistry at grain boundaries and sub-grain boundaries due to slow cooling.

关键词： 7xxx aluminum alloy cooling rate exfoliation corrosion microstructure