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Responses of the Southern Ocean mixed layer depth to the eastern and central Pacific El Niño events during austral winter

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Acta Oceanologica Sinica 2024年第7期43卷 1-14页

作者： Yuxin shi Hailong Liu Xidong wang Quanan Zheng School of Oceanography Shanghai Jiao Tong UniversityShanghai 200240China Yunnan Key Laboratory of Meteorological Disasters and Climate Resources in the Greater Mekong Subregion Yunnan UniversityKunming 600650China College of Oceanography Hohai UniversityNanjing 210098China Department of Atmospheric and Oceanic Science University of Maryland at College ParkCollege Park 20742USA

Based on the Ocean Reanalysis System version 5(ORAS5)and the fifth-generation reanalysis datasets derived from European Centre for Medium-Range Weather Forecasts(ERA5),we investigate the different impacts of the central Pacific(CP)El Niño and the eastern Pacific(EP)El Niño on the Southern Ocean(SO)mixed layer depth(MLD)during austral *** MLD response to the EP El Niño shows a dipole pattern in the South Pacific,namely the MLD dipole,which is the leading El Niño-induced MLD variability in the *** tropical Pacific warm sea surface temperature anomaly(SSTA)signal associated with the EP El Niño excites a Rossby wave train propagating southeastward and then enhances the Amundsen Sea low(ASL).This results in an anomalous cyclone over the Amundsen *** a result,the anomalous southerly wind to the west of this anomalous cyclone advects colder and drier air into the southeast of New Zealand,leading to surface cooling through less total surface heat flux,especially surface sensible heat(SH)flux and latent heat(LH)flux,and thus contributing to the mix layer(ML)*** east of the anomalous cyclone brings warmer and wetter air to the southwest of Chile,but the total heat flux anomaly shows no significant *** warm air promotes the sea ice melting and maintains fresh water,which strengthens *** results in a shallower *** the CP El Niño,the response of MLD shows a separate negative MLD anomaly center in the central South *** Rossby wave train triggered by the warm SSTA in the central Pacific Ocean spreads to the Amundsen Sea,which weakens the ***,the anomalous anticyclone dominates the Amundsen ***,the anomalous northerly wind to the west of anomalous anticyclone advects warmer and wetter air into the central and southern Pacific,causing surface warming through increased SH,LH,and longwave radiation flux,and thus contributing to the ML ***,to the east of the anomalous anticyclone,there is n

关键词： Southern Ocean mixed layer depth Central Pacific El Niño Eastern Pacific El Niño Rossby wave train

Model Parameters Identification and Backstepping Control of Lower Limb Exoskeleton Based on Enhanced Whale Algorithm

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Chinese Journal of Mechanical Engineering 2024年第2期37卷 100-114页

作者： Yan shi Jiange Kou Zhenlei Chen Yixuan wang Qing Guo School of Automation Science and Electrical Engineering Beihang UniversityBeijing 100191China School of Aeronautics and Astronautics University of Electronic Science and Technology of ChinaChengdu 611731China

Exoskeletons generally require accurate dynamic models to design the model-based controller conveniently under the human-robot interaction ***,due to unknown model parameters such as the mass,moment of inertia and mechanical size,the dynamic model of exoskeletons is difficult to ***,an enhanced whale optimization algorithm(EWOA)is proposed to identify the exoskeleton model ***,the periodic excitation trajectories are designed by finite Fourier series to input the desired position demand of exoskeletons with mechanical physical *** a backstepping controller based on the identified model is adopted to improve the human-robot wearable comfortable performance under cooperative ***,the proposed Model parameters identification and control are verified by a two-DOF exoskeletons *** knee joint motion achieves a steady-state response after 0.5 ***,the position error of hip joint response is less than 0.03 rad after 0.9 *** addition,the steady-state human-robot interaction torque of the two joints is constrained within 15 N·*** research proposes a whale optimization algorithm to optimize the excitation trajectory and identify model ***,an enhanced mutation strategy is adopted to avoid whale evolution’s unsatisfactory local optimal value.

关键词： Parameter identification Enhanced whale optimization algorithm(EWOA) Backstepping Human-robot interaction Lower limb exoskeleton

Recent progress in the development of dielectric elastomer materials and their multilayer actuators

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2024年第3期25卷 183-205页

作者： Shengchao JIANG Junbo PENG Lvting wang Hanzhi MA Ye shi ZJU-UIUC Institute Zhejiang UniversityJiaxing 314400China College of Mechanical Engineering Zhejiang UniversityHangzhou 310058China Department of Polymer Science and Engineering Zhejiang UniversityHangzhou 310058China

Dielectric elastomers(DEs)have emerged as one of the most promising artificial muscle technologies,due to their exceptional properties such as large actuation strain,fast response,high energy density,and flexible processibility for various *** the past two decades,researchers have been working on developing DE materials with improved properties and exploring innovative applications of dielectric elastomer actuators(DEAs).This review article focuses on two main topics:recent material innovation of DEs and development of multilayer stacking processes for DEAs,which are important to promoting commercialization of *** begins by explaining the working principle of a ***,recently developed strategies for preparing new DE materials are introduced,including reducing mechanical stiffness,increasing dielectric permittivity,suppressing viscoelasticity loss,and mitigating electromechanical instability without *** the next section,different multilayer stacking methods for fabricating multilayer DEAs are discussed,including conventional dry stacking,wet stacking,a novel dry stacking method,and micro-fabrication-enabled stacking *** review provides a comprehensive and up-to-date overview of recent developments in high-performance DE materials and multilayer stacking *** highlights the progress made in the field and also discusses potential future directions for further advancements.

关键词： Dielectric elastomer actuator(DEA) Dielectric elastomer(DE) Material svnthesis Multilaver stacking method

Command filtered integrated estimation guidance and control for strapdown missiles with circular field of view

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Defence Technology（防务技术） 2024年第5期35卷 211-221页

作者： Wei wang Jiaqi Liu shiyao Lin Baokui Geng Zhongjiao shi School of Aerospace Engineering Beijing Institute of TechnologyBeijing 10081China China Research and Development Academy of Machinery Equipment Beijing 100089China Northwest Industries Group CO. Ltd.Xi'an 710043China

In this paper,an integrated estimation guidance and control(IEGC)system is designed based on the command filtered backstepping approach for circular field-of-view(FOV)strapdown *** threedimensional integrated estimation guidance and control nonlinear model with limited actuator deflection angle is established considering the seeker's FOV *** boundary time-varying integral barrier Lyapunov function(IBLF)is employed in backstepping design to constrain the body line-of-sight(BLOS)in IEGC system to fit a circular ***,the nonlinear adaptive controller is designed to estimate the changing aerodynamic *** generalized extended state observer(GESO)is designed to estimate the acceleration of the maneuvering targets and the unmatched time-varying disturbances for improving tracking ***,the command filters are used to solve the"differential expansion"problem during the backstepping *** Lyapunov theory is used to prove the stability of the overall closed-loop IEGC ***,the simulation results validate the integrated system's effectiveness,achieving high accuracy strikes against maneuvering targets.

关键词： Integrated estimation guidance and control Circular field-of-view Time-varying integral barrier Lyapunov function Command filtered backstepping control Nonlinear adaptive control Extended state observer

A multi-scale framework for life reduction assessment of turbine blade caused by microstructural degradation

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Chinese Journal of Aeronautics 2024年第1期37卷 186-200页

作者： Xiaoguang YANG Menglei wang Duoqi shi Zhenlei LI Yongsheng FAN School of Energy and Power Engineering Beihang UniversityBeijing 102206China Research Institute of Aero-Engine Beihang UniversityBeijing 102206China National Key Laboratory of Science and Technology on Aero-Engine Aero-Thermodynamics Beihang UniversityBeijing 102206China

The prolonged thermal exposure with centrifugal load results in microstructural degradation,which ultimately leads to a reduction in the fatigue and creep resistance of the turbine *** present work proposes a multi-scale framework to estimate the life reduction of turbine blades,which combines a microstructural degradation model,a two-phase constitutive model,and a microstructure-dependent fatigue and creep life reduction *** framework with multi-scale models is validated by a Single Crystal(SC)Ni-based superalloy at the microstructural length-scale and is then applied to calculate the microstructural degradation and the fatigue and creep life reduction of turbine blades under two specific service *** simulation results and quantitative analysis show that the microstructural degradation and fatigue and creep life reduction of the turbine blade are heavily influenced by the variations in the proportion of the intermediate state,namely,the maximum rotor speed status,in the two specific service *** intermediate state accelerates the microstructural degradation and leads to a reduction of the life,especially the effective fatigue life reserve due to the higher temperature and rotational speed than that of the 93%maximum rotor speed status marked as the reference *** proposed multi-scale framework provides a capable approach to analyze the reduction of the fatigue and creep life for turbine blade induced by microstructural degradation,which can assist to determine a reasonable Time Between Overhaul(TBO)of the engine.

关键词： Creep Fatigue Life reduction Microstructural degradation Multi-scale modeling Turbine blades

Effect of electrical parameters and slag system on macrostructure of electroslag ingot

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China Foundry 2024年第1期21卷 44-50页

作者： Bing-jie wang Yu wang Meng-jun wang Lei Zhao Li-zhong Chang Xiao-fang shi School of Metallurgy engineering Anhui University of TechnologyMa'anshan 243002AnhuiChina

To investigate the influence of electric parameters and slag system on the solidification quality of electroslag ingot during electroslag remelting,different power supply modes,current strengths and remelting slag systems were used to conduct electroslag remelting experiments on 304L austenitic stainless steel,and the macrostructure of electroslag ingots was *** results indicate that the depth of the metal pool decreases with the reduction of remelting frequency in the low frequency power supply *** effects of different power supply modes,such as low-frequency,direct current straight polarity(DCSP),and direct current reverse polarity(DCRP),on reducing the depth of the metal pool increase in that *** reducing the remelting current strength in the same power supply mode,the depth of metal pool is *** compared to the binary slag system of 70%CaF2+30%Al2O3,the ternary slag system of 60%CaF2+20%Al2O3+20%CaO is more effective in reducing the depth of the metal pool during *** the 60%CaF2+20%Al2O3+20%CaO ternary slag system results in a shallower and flatter metal pool,with columnar crystal growth occurring closer to the axial *** effect is observed for both low frequency and direct current(DC)power supply modes.

关键词： electroslag remelting frequency slag system solidification quality

A Simple-Prepared and Multi-Reusable Adhesive Based on Epoxy Vitrimer

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Chinese Journal of Polymer Science 2024年第10期42卷 1589-1594,I0015页

作者： Yu-Ting wang Huan Liang Yen Wei Jian-long wang Xiang-Ming He Yang Yang Institute of Nuclear and New Energy Technology Tsinghua UniversityBeijing100084China The Key Laboratory of Bioorganic Phosphorus Chemistry&Chemical Biology(Ministry of Education) Department of ChemistryTsinghua UniversityBeijing100084China

Adhesives play an important role in modern society's production and daily *** robust and sustainable adhesives remains a great *** we report a sustainable epoxy-vitrimer adhesive with high adhesive strength(about 10 MPa)and reusability(82%strength after 3 times).This adhesive can be fabricated from commercially available products through a straightforward hot-pressing method without the need of *** adhesive process is also simple,requiring only 30 min at 180℃.In addition,the vitrimer adhesive has the advantages of both erasability for reuse and excellent water *** work provides a facile strategy to fabricate high-strength adhesive that ensures reusability,recyclability,low cost of raw materials,and simple processing ***,it expands the range of potential applications for epoxy vitrimers.

关键词： Epoxy Vitrimer Adhesive Reusable Sustainable

Seismic stability of expansive soil slopes reinforced by anchor cables using a modified horizontal slice method

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Earthquake Engineering and Engineering Vibration 2024年第2期23卷 377-387页

作者： wang long Chen Guoxing Hu Wei Zhou Enquan Feng Jianxue Huang Anping School of Mechnical Engineering Jiangnan UniversityWuxi 214122China Institute of Geotechnical Engineering Nanjing Tech UniversityNanjing 211816China State Key Laboratory of Geohazard Prevention and Geoenvironmental Protection Chengdu University of TechnologyChengdu 610059China Faculty of Civil Engineering and Mechanics Jiangsu UniversityZhenjiang 212013China Architectural Engineering College Guizhou Minzu UniversityGuiyang 550025China School of Civil Engineering Lanzhou University of TechnologyLanzhou 730050China

Earthquake-induced slope failures are common occurrences in engineering practice and pre-stressed anchor cables are an effective technique in maintaining slope stability,especially in areas that are prone to ***,the soil at typical engineering sites also exhibit unsaturated *** considerations of these factors in slope stability estimations are crucial in producing accurate *** this study,the seismic responses of expansive soil slopes stabilized by anchor cables is studied in the realm of kinematic limit analysis.A modified horizontal slice method is proposed to semi-analytically formulate the energy balance *** illustrative slope is studied to demonstrate the influences of suction,seismic excitations and anchor cables on the slope *** results indicate that the stabilizing effect of soil suction relates strongly to the seismic excitation and presents a sine shape as the seismic wave *** higher and steeper slopes,the stabilizing effect of suction is more *** critical slip surface tends to be much more shallow as the seismic wave approaches the peak and vice versa.

关键词： limit analysis expansive soil slope matric suction anchor cable pseudo-dynamic analysis

Study of the multi-physics field-coupled model of the two-stage electrostatic precipitator

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Building Simulation 2024年第3期17卷 387-398页

作者： Wenjia Hao Yu Guo Yukun wang Tao Yu Hao Gao Zhengwei long Tianjin Key Laboratory of Indoor Air Environmental Quality Control School of Environmental Science and EngineeringTianjin UniversityWeijin Road 92Tianjin300072China Wuhan Second ship Design and Research Institute WuhanChin

The two-stage electrostatic precipitator is widely used to purify oil mist ***,there is limited research on the influences of relative humidity,particle deposition characteristics,and the generation of gaseous ***,this paper established a numerical model of the electrostatic oil mist purifier and applied it to a two-stage electrostatic *** the model was used to investigate the corona discharge characteristics under different relative humidity conditions in the charged zone,the particle deposition characteristics,the purification efficiency,the ozone concentration distribution,and the oil vapor concentration distribution in the collection *** results indicate that,with a constant temperature,the corona current decreases as relative humidity increase,and there is a quadratic relationship between relative humidity and *** variation in relative humidity has little impact on the purification *** maximum ozone concentration occurs near the electrode line,and its concentration is influenced by the discharge current and inlet airflow *** oil vapor concentration reaches its maximum value at the side plates,with a value of 19 ppb,while it reaches the minimum value at the collecting zone electrode plate,with a value of 2 *** temperature is the main factor affecting the volatilization of the oil film,with higher temperatures resulting in higher oil vapor.

关键词： two-stage ESPs particle deposition corona discharge oil vapor