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Will the 2022 compound heatwaveedrought extreme over the Yangtze River Basin become Grey Rhino in the future?

Advances in Climate Change Research 2024年第3期15卷 547-556页

作者： Ai-Qing FENG Qing-Chen CHAO lu-lu liu Ge GAO Guo-Fu WANG Xue-Jun ZHANG Qi-Guang WANG China Meteorological Administration Key Laboratory for Climate Prediction Studies National Climate CentreBeijing 100081China Key Laboratory of Land Surface Pattern and Simulation Institute of Geographic Sciences and Natural Resources ResearchChinese Academy of SciencesBeijing 100101China China Institute of Water Resources and Hydropower Research Beijing 100038China China Meteorological Administration Training Centre China Meteorological AdministrationBeijing 100081China

The increasingly frequent and severe regional-scale compound heatwave-drought extreme events(CHDEs),driven by global warming,present formidable challenges to ecosystems,residential livelihoods,and economic ***,uncertainty persists regarding the future trend of CHDEs and their insights into regional spatiotemporal *** integrating daily meteorological data from observations in 1961-2022 and global climate models(GCMs)based on the Shared Socioeconomic Pathways,the evolution patterns of CHDEs were compared and examined among three sub-catchments of the Yangtze River Basin,and the return periods of CHDE in 2050s and 210Os were *** findings indicate that the climate during the 2022 CHDE period was the warmest and driest recorded in 1961-2022,with precipitation less than 154.5 mm and a mean daily maximum temperature 3.4°C higher than the average of 1981-2010,whereas the char-acteristics in the sub-catchments exhibited temporal and spatial *** July-August 2022,the most notable feature of CHDE was its extremeness since 1961,with return periods of~200-year in upstream,80-year in midstream,and 40-year in downstream,*** 2050,the return periods witnessed 2022 CHDE would likely be reduced by *** towards 2100,under the highest emission scenario of SSP585,it was projected to substantially increase the frequency of CHDEs,with return periods reduced to one-third in the upstream and downstream,as well as halved in the *** findings provide valuable insights into the changing risks associated with forthcoming climate extremes,emphasizing the urgency of addressing these challenges in regional management and sustainable development.

关键词： Compound extreme event Joint return period Drought Heatwave Climate change Yangtze River Basin

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A modified constitutive model for FRP confined concrete in circular sections and its implementation with OpenSees programming

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2013年第12期14卷 856-866页

作者： Hui liu Ming-hua HE Yu-qi luAN Jia GUO lu-lu liu Department of Civil Engineering Tsinghua University Research Institute of Highway of China Ministry of Transport Institute of Chemical Machinery Zhejiang University

OpenSees is a well-recognized open source platform with high compatibility,and it has a well-developed fiber element method to cope with nonlinear structural *** reinforced polymer(FRP)confined concrete can effectively improve the seismic performance of concrete ***,sophisticated constitutive models for FRP confined concrete are not available in the current version of *** this paper,after reviewing several typical FRP confined concrete constitutive models,a modified constitutive model for FRP confined concrete in circular sections was proposed based on Lam and Teng(2003)’s model with four main modifications including the determination of FRP rupture strain,ultimate condition,envelope shape,and hysteretic *** embed the proposed constitutive model into OpenSees is a practical solution for engineering ***,the secondary development of OpenSees New UserMat was briefly demonstrated and a set of critical steps were depicted in a flow ***,with the numerical implementations of a series of FRP confined concrete members covering a wide range of load cases,FRP confinement types and geometric properties,the utility and accuracy of the proposed model compared with Lam and Teng(2003)’s model and new material secondary development in OpenSees were well validated.

关键词： FRP confined concrete Constitutive model OpenSees User material Secondary development

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Containment of high-speed rotating disk fragments

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Journal of Zhejiang University-Science A(Applied Physics & Engineering) 2012年第9期13卷 665-673页

作者： Hai-jun XUAN lu-lu liu Yi-ming FENG Qing HE Juan-juan LI High-Speed Rotating Machinery Laboratory Institllte of Chemical MachineryFacldly of EngineeringZhejiang UniversityHangzhou 310027China

Disk burst accidents sometimes happen in *** avoid tragic consequences,aeroengine casings must have sufficient containment *** and simulations need to be conducted to study the impact,distortion,and perforation caused by disk burst and which may give important clues to potential failure *** paper presents some containment tests of high-speed rotating disk fragments,in which the original disks were burst into three equal fragments within a predetermined rotating speed *** failure modes of the containment casing varied significantly with the thickness of the containment ***,tearing,tensile fracture,and large plastic stretching deformation occurred in a thin-walled containment casing,while a thick-walled casing could contain disk fragments and withstand large plastic *** simulations were carried out to study the impact process and failure modes *** agreement was found between the results of the simulations and the tests.

关键词： Aeroengine Disk fragments Engine casing Containment capability Numerical simulation

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Numerical Analysis of Effect of Water on Explosive Wave Propagation in Tunnels and Surrounding Rock

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Journal of China University of Mining and Technology 2007年第3期17卷 368-371页

作者： XIA Chang-jing SONG Zhen-duo TIAN lu-lu liu Hong-bin WANG lu WU Xiao-fang School of Mechanics ＆ Civil Engineering China University of Mining ＆ Technology Beijing 100083 China

Based on the application of practical engineering,propagation processes of explosive waves in rock with water well and tunnel are simulated by ANSYS/LS-DYNA software. The evolution of damage in rock is presented. The effect of water on the damage of the concrete slab in a tunnel is compared with damage inflicted without water. The numerical simulation illustrates that water plays an important role in the evolution of damage of the concrete slab in a mine tunnel. In the presence of water in the rock the concrete slab is damaged more severely than without water in rock. The effect of water location in the rock is also considered. It is found that the concrete slab in the tunnel shows various degrees of damage as a function of the different locations of water. Attenuation laws of stress waves over time-space in rock with water are also obtained. Numerical results indicate that,under blast loading,there are three zones in the rock: a crushed zone nearby the explosive charge,a damaged zone and an elastic zone. The conclusions of numerical analysis may provide references for blasting designs and structure protection.

关键词： explosive wave numerical simulation concrete slab damage evolution

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Tuning mechanical behaviors of highly entangled hydrogels with the random distribution of mobile entanglements

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Applied Mathematics and Mechanics(English Edition) 2024年第2期45卷 277-294页

作者： Jinlong liu Di lu Bin CHEN Department of Engineering Mechanics Zhejiang UniversityHangzhou 310027China Beijing System Design Institute of Electro-Mechanic Engineering Beijing 100854China Intelligent Robotic Research Center Zhejiang LaboratoryHangzhou 310027China Key Laboratory of Soft Machines and Smart Devices of Zhejiang Province Hangzhou 311100China

Highly entangled hydrogels exhibit excellent mechanical properties,including high toughness,high stretchability,and low *** considering the evolution of randomly distributed entanglements within the polymer network upon mechanical stretches,we develop a constitutive theory to describe the large stretch behaviors of these *** the theory,we utilize a representative volume element(RVE)in the shape of a cube,within which there exists an averaged chain segment along each edge and a mobile entanglement at each *** employing an explicit method,we decouple the elasticity of the hydrogels from the sliding motion of their entanglements,and derive the stress-stretch relations for these *** present theoretical analysis is in agreement with experiment,and highlights the significant influence of the entanglement distribution within the hydrogels on their *** also implement the present developed constitutive theory into a commercial finite element software,and the subsequent simulations demonstrate that the exact distribution of entanglements strongly affects the mechanical behaviors of the structures of these ***,the present theory provides valuable insights into the deformation mechanism of highly entangled hydrogels,and can aid in the design of these hydrogels with enhanced performance.

关键词： highly entangled hydrogel constitutive theory entanglement gamma distribution

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FedDAA:a robust federated learning framework to protect privacy and defend against adversarial attack

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Frontiers of Computer Science 2024年第2期18卷 107-122页

作者： Shiwei lu Ruihu LI Wenbin liu Fundamentals Department Air Force Engineering UniversityXi’an 710051China Institute of Advanced Computational Science and Technology Guangzhou UniversityGuangzhou 510006China

Federated learning(FL)has emerged to break data-silo and protect clients’privacy in the field of artificial ***,deep leakage from gradient(DLG)attack can fully reconstruct clients’data from the submitted gradient,which threatens the fundamental privacy of *** cryptology and differential privacy prevent privacy leakage from gradient,they bring negative effect on communication overhead or model ***,the original distribution of local gradient has been changed in these schemes,which makes it difficult to defend against adversarial *** this paper,we propose a novel federated learning framework with model decomposition,aggregation and assembling(FedDAA),along with a training algorithm,to train federated model,where local gradient is decomposed into multiple blocks and sent to different proxy servers to complete *** bring better privacy protection performance to FedDAA,an indicator is designed based on image structural similarity to measure privacy leakage under DLG attack and an optimization method is given to protect privacy with the least proxy *** addition,we give defense schemes against adversarial attack in FedDAA and design an algorithm to verify the correctness of aggregated *** results demonstrate that FedDAA can reduce the structural similarity between the reconstructed image and the original image to 0.014 and remain model convergence accuracy as 0.952,thus having the best privacy protection performance and model training *** importantly,defense schemes against adversarial attack are compatible with privacy protection in FedDAA and the defense effects are not weaker than those in the traditional ***,verification algorithm of aggregation results brings about negligible overhead to FedDAA.

关键词： federated learning privacy protection adversarial attacks aggregated rule correctness verification

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Fast measurement and prediction method for electromagnetic susceptibility of receiver

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Journal of Systems Engineering and Electronics 2024年第2期35卷 275-285页

作者： CHEN Yan lu Zhonghao liu Yunxia State Key Laboratory of Complex Electromagnetic Environment Effects on Electronics and Information System College of Electronic Science and TechnologyNational University of Defense TechnologyChangsha 410073China State Key Laboratory of Astronautic Dynamics Xi’an 710043China

Aiming at evaluating and predicting rapidly and accurately a high sensitivity receiver’s adaptability in complex electromagnetic environments,a novel testing and prediction method based on dual-channel multi-frequency is proposed to improve the traditional two-tone ***,two signal generators are used to generate signals at the radio frequency(RF)by frequency scanning,and then a rapid measurement at the intermediate frequency(IF)output port is carried out to obtain a huge amount of sample data for the subsequent ***,the IF output response data are modeled and analyzed to construct the linear and nonlinear response constraint equations in the frequency domain and prediction models in the power domain,which provide the theoretical criteria for interpreting and predicting electromagnetic susceptibility(EMS)of the *** experiment performed on a radar receiver confirms the reliability of the method proposed in this *** shows that the interference of each harmonic frequency and each order to the receiver can be identified and predicted with the sensitivity *** on this,fast and comprehensive evaluation and prediction of the receiver’s EMS in complex environment can be efficiently realized.

关键词： electromagnetic susceptibility(EMS) receiver dualchannel multi-frequency nonlinear response frequency domain power domain

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Enlarged interlayer of separator coating enabling high-performance lithiumsulfur batteries

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Frontiers of Chemical Science and Engineering 2024年第2期18卷 103-112页

作者： Yanqi Feng Hui liu Xiaoting liu Qiongqiong lu School of Materials&Environment Engineering Chengdu Technological UniversityChengdu 611730China School of Materials Science and Engineering Shaanxi Key Laboratory of Green Preparation and Functionalization for Inorganic MaterialsShaanxi University of Science and TechnologyXi’an 710021China Green Catalysis Center and College of ChemistryZhengzhou UniversityZhengzhou 450001China Institute of Materials Henan Key Laboratory of Advanced Conductor MaterialsHenan Academy of SciencesZhengzhou 450046China Leibniz Institute for Solid State and Materials Research(IFW) Dresden e.V.Dresden 01069Germany

Lithiumsulfur batteries have been intensively studied due to their high theoretical energy density and abundant sulfur resources. However, their commercial application is hindered by the low redox kinetics and high sulfur losses. In principle, in the design of cathodes and separators, the adsorption toward lithium-polysulfides should be enhanced and the conversion of soluble high-order lithium-polysulfides should be catalyzed. Herein, a KV_(3)O_(8)·0.75H_(2)O separator is designed as an effective lithium-polysulfides mediator in lithiumsulfur batteries. The intercalated K+ would enlarge the interlayer spacing of vanadium oxides, preventing the collapse of the layer structure and improving the electrical/ion conductivity of the interface. Moreover, the KV_(3)O_(8)·0.75H_(2)O modified separator possess a prior adsorption and high redox kinetics toward lithium-polysulfides due to the enhanced diffusion kinetics, which guarantees the high-rate capability and efficient utilization of sulfur. As a result, lithiumsulfur batteries exhibit a high capacity of 1362 mAh·g^(-1) and a long lifespan with a low capacity loss of 0.073% per cycle. This work may provide an alternative way to establish a functional separator to balance the adsorption and conversion of polysulfides during the redox back and forth.

关键词： lithium kinetics adsorption

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Engineering in amino acid-functionalized double-layer heteropolymolybdates:from structural control to catalytic activity

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Rare Metals 2023年第10期42卷 3345-3353页

作者： lu-lu liu Yan-Hu Wang Xin-Yu Xiao Ke-Wei Tong Yue Zhao Chao-Qin Chen Jing Du Peng Yang College of Chemistry and Chemical Engineering Advanced Catalytic Engineering Research Center of the Ministry of EducationHunan UniversityChangsha410082China Testing and Analysis Center Hebei Normal UniversityShijiazhuang050024China

A reexamination of the structural constraints on the amino acid-functionalized heteropolymolybdates has afforded four polyanions,namely the double-layer [(SeO_(3))_(2)Mo_(12)O_(36)(CH_(3)COO)_(3)]^(7-)(1),[(SeO_(3))_(1.3)(HPO_(3))_(0.7)Mo_(12)O_(36)(NH_(3)CH_(2)COO)_(3)]^(4-)(2),[(SeO_(3))_(1.4)(HPO_(3))_(0.6)Mo_(12)O_(36)(LNH_(3)C_(2)H_(3)OHCOO)_(3)]^(4-)(3),and the mono-layer [(SeO_(3))-Mo_6O_(18)(L-NH_(3)C_(2)H_(3)OHCOO)_(3)]^(2-)(4),which were crystallized as the hydrated ammonium salts.

关键词： structural layer double

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From non-carbon host toward carbon-free lithium-sulfur batteries

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Nano Research 2024年第3期17卷 1337-1365页

作者： Yanqi Feng Hui liu Qiongqiong lu School of Materials Science and Engineering Shaanxi Key Laboratory of Green Preparation and Functionalization for Inorganic MaterialsShaanxi University of Science and TechnologyXi’an 710021China Institute of Materials Henan Key Laboratory of Advanced Conductor MaterialsHenan Academy of SciencesZhengzhou 450046China Leibniz Institute for Solid State and Materials Research(IFW)Dresden e.V. Helmholtzstraβe 2001069 DresdenGermany School of Materials&Environment Engineering Chengdu Technological UniversityChengdu 611730China

Lithium-sulfur(Li-S)batteries with advantages of high energy densities(2600 Wh·kg^(-1)/2800 Wh·L^(-1))and sulfur abundance are regarded as promising candidates for next-generation high-energy ***,the conventional carbon host used in sulfur cathodes suffers from poor chemical adsorption towards Li-polysulfides(LPS)in liquid electrolyte and sluggish redox kinetics,leading to low capacity and rate ***,carbon host used in Li metal anode with the intrinsic property of poor lithiophilicity and high Li-nucleation barrier gives rise to uncontrollable dendrite growth and further battery ***,non-carbon hosts with chemical adsorption toward LPS and catalytic activity for accelerating LPS redox conversion as well as lithiophilic property for guiding uniform Li deposition are proposed and demonstrated a high efficiency in both sulfur cathodes and Li metal *** this review,the principle and challenges of Li-S batteries are first presented,then recent work using non-carbon hosts in Li-S batteries is summarized comprehensively,and the mechanism of non-carbon host in improving sulfur utilization and stabilizing Li metal anode is discussed in ***,remaining challenges and outlook on the implementation of non-carbon host for practical carbon-free Li-S batteries are also provided.

关键词： sulfur cathode Li metal anode polysulfides adsorption catalytic effect Li dendrite carbon-free lithium-sulfur batteries

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