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Switching,explosion,and chaos of multi-wavelength soliton states in ultrafast fiber lasers

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Science China(Physics,Mechanics & Astronomy) 2024年第7期67卷 82-90页

作者： Zhi-Zeng Si Yue-Yue wang chao-qing Dai College of Optical Mechanical and Electrical EngineeringZhejiang A&F UniversityLin’an 311300China

Because of the complexity and difficulty of realizing a multi-wavelength soliton state,reports on its internal dynamic characteristics are *** this study,the switching and periodic soliton explosion processes of the multi-wavelength soliton state in a negative dispersion passively mode-locked fiber laser are *** generation of the multi-wavelength soliton state undergoes the process of noise,oscillation,and stable mode-locking,and the splitting and annihilation of solitons with different group velocities directly impact the generation and disappearance of three *** and negative dispersion lead to different group velocities of *** presence and displacement of solitons with different group velocities cause soliton collisions,which lead to soliton explosions.A soliton experiences relative phase oscillation,chaos,and oscillation,as well as convergence and separation before and after an *** an increase in parameters related to pump power,single-soliton oscillation,multi-wavelength solitons,and chaos are found in experiments and simulations,proving the relevance and reliability between simulation and experimental *** work promotes the dynamical study of multi-soliton collisions in nonlinear science and the development of chaos theory in multi-comb lasers.

关键词： multi-wavelength fiber laser soliton explosion chaos state switching real-time dynamics

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Application of machine learning models in groundwater quality assessment and prediction:progress and challenges

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Frontiers of Environmental Science & Engineering 2024年第3期18卷 25-55页

作者： Yanpeng Huang chao wang Yuanhao wang Guangfeng Lyu Sijie Lin Weijiang Liu Haobo Niu qing Hu School of Environment Harbin Institute of TechnologyHarbin 150090China School of Environmental Science and Engineering Southern University of Science and TechnologyShenzhen 518055China Engineering Innovation Center of SUSTech(Beijing) Southern University of Science and TechnologyBeijing 100083China Technical Center for Soil Agriculture and Rural Ecology and EnvironmentMinistry of Ecology and EnvironmentBeijing 100012China Chinese Academy of Environmental Planning Beijing 100043China

Groundwater quality assessment and prediction(GQAP)is vital for protecting groundwater *** GQAP methods can not adequately capture the complex relationships among attributes and have the disadvantage of being computationally ***,the application of machine learning(ML)in GAQP(GQAPxML)has been widely studied due to ML’s reliability and *** many GQAPxML publications exist,a thorough review is *** review provides a comprehensive summary of the development of ML applications in the field of ***,the workflow of ML modeling is briefly introduced,as are data preparation,model development,model evaluation,and model ***,299 publications related to the topic are filtered,mainly through ML ***,many aspects of GQAPxML,such as publication trends,the spatial distribution of study areas,the size of data sets,and ML algorithms,are discussed from a bibliometric *** addition,we review in detail the well-established applications and recent findings for several subtopics,including groundwater quality assessment,groundwater quality modeling using groundwater quality parameters,groundwater quality spatial mapping,probability estimation of exceeding the groundwater quality threshold,groundwater quality temporal prediction,and the hybrid use of ML and physics-based ***,the development of GQAPxML is explored from three perspectives:data collection and preprocessing,model building and evaluation,and the broadening of model *** review provides a reference for environmental scientists to better understand GQAPxML and promotes the development of innovative methods and improvements in modeling quality.

关键词： Groundwater quality assessment Groundwater quality prediction Machine learning Groundwater modeling

Polyoxometalates-derived nanostructures for electrocatalysis application

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Rare Metals 2024年第5期43卷 1845-1866页

作者： chao-Yue Sun Wen Li Kai wang Wei-Jia Zhou Hai-qing wang Institute for Advanced Interdisciplinary Research(iAIR) College of Chemistry and Chemical EngineeringUniversity of JinanJinan250022China Shandong Electrical Engineering and Equipment Group Intelligent Electric Co. Ltd.Jinan 250022China

The conversion of intermittent renewable electrical energy to chemical energy is of great importance which can not only mitigate current energy and environmental crisis but also contribute to the ongoing carbon neutrality national *** is serving as a low-carbon conversion technology that enables green and efficient energy conversion mainly through hydrogen evolution reaction(HER),carbon dioxide reduction reaction(CO_(2)RR),and nitrogen reduction reaction(NRR).The core of electrocatalysis is the design and construction of low-cost high-activity and high-stability electrocatalyst to drive reaction thermodynamics and *** employment of polyoxometalates(POMs)as platforms or precursors to construct different types of electrocatalysts has been widely ***,we systematically summarized the recent advances in POM-derived nanostructures for electrocatalysis *** strategies for precursor design and electrocatalyst synthesis were briefly *** morphology control,phase control,composite modulation,and heterostructure engineering in POM-derived nanostructures were presented in *** structure–activity relationship of POM-derived nanostructures is fully discussed for HER CO_(2)RR,and NRR ***,the current challenges and future outlooks of POM-derived nanostructures are summarized to provide insights toward high-efficiency electrocatalysts for energy conversion technologies.

关键词： Microforming Cylindrical compression Size effects Grain orientation Inhomogeneous deformation

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

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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

Enhancement of comprehensive properties of Nb–Si based in-situ composites by Ho rare earth doping

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Rare Metals 2024年第9期43卷 4508-4520页

作者： Wei Wei Qi wang Rui-Run Chen chao-Wen Zheng Yan-qing Su National Key Laboratory for Precision Hot Processing of Metals School of Materials Science and EngineeringHarbin Institute of Technology

This study examines the microstructure,mechanical properties （with a focus on room-temperature toughness）, and oxidation resistance of Ho-doped NbDSi based in-situ composites. The base alloy consists of the coarse primary Nb5Si3phase and the Nb5Si3+Nbss （Nb solid solution） eutectic cells. Ho doping influences the solidification path. When the Ho doping is higher than0.2 at%, the alloys transform into eutectic alloys. Ho can be solid-solved in trace amounts in the Nbss phase. However, most of Ho forms a stable Ho oxide phase, which alleviates oxygen contamination problem to some ***, the interface separation between Ho oxide and other phases reduces the plastic deformation ***, with 0.4 at%Ho doping, the KQvalue is18.03 MPa·m1/2, which is 31.1%higher than that of the base alloy. The strength of the Ho-doped alloys does not deteriorate with an increase in toughness. However, the large network-like Ho2O3in the 0.8Ho alloy causes a decrease in toughness and strength. In addition, the Ho oxide phase effectively blocks the inward oxygen *** 0.8 at%Ho doping, the oxidation mass gain per unit area is 10.16 mg·cm2, which is 39.7%lower than that of the base alloy.

关键词： Ho Microstructure Nb–Si based composites Properties Rare earth elements

Wiener model identification and nonlinear model predictive control of a pH neutralization process based on Laguerre filters and least squares support vector machines

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Journal of Zhejiang University-Science C(Computers and Electronics) 2011年第1期12卷 25-35页

作者： qing-chao wang Jian-zhong ZHANG School of Energy Science and Engineering Harbin Institute of Technology Harbin 150001 China SINOPEC Safety Engineering Institute Qingdao 266071 China

This paper deals with Wiener model based predictive control of a pH neutralization *** dynamic linear block of the Wiener model is parameterized using Laguerre filters while the nonlinear block is constructed using least squares support vector machines (LSSVM).Input-output data from the first principle model of the pH neutralization process are used for the Wiener model *** results show that the proposed Wiener model has higher prediction accuracy than Laguerre-support vector regression (SVR) Wiener models,Laguerre-polynomial Wiener models,and linear Laguerre *** identified Wiener model is used here for nonlinear model predictive control (NMPC) of the pH neutralization *** set-point tracking performance of the proposed NMPC is compared with those of the Laguerre-SVR Wiener model based NMPC,Laguerre-polynomial Wiener model based NMPC,and linear model predictive control (LMPC).Validation results show that the proposed NMPC outperforms the other three controllers.

关键词： Wiener model Nonlinear model predictive control (NMPC) pH neutralization process Laguerre filters Least squares support vector machines (LSSVM)

Different responses of two adjacent artificial beaches to Typhoon Hato in Zhuhai,China

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Journal of Oceanology and Limnology 2024年第2期42卷 511-521页

作者： Jun ZHU qing wang chao ZHAN Fengjuan SUN Wenhao HUA Jianhui LIU Hongshuai QI Yu YANG Coastal Research Institute Ludong UniversityYantai 264025China Third Institute of Oceanography Ministry of Natural ResourcesXiamen 261005China

Major differences in beach erosion between two neighboring artificial beaches Xiangluwan Beach(XL beach)and Meiliwan Beach(ML beach)in Zhuhai,China,were studied after Super Typhoon *** this study,a fully nonlinear Boussinesq wave model(FUNWAVE)-Total Variation Diminishing(TVD)was used to distinguish the main impact factors,their relative contributions,and the hydrodynamic mechanisms underlying the different beach *** show that compared to the ML beach,the main reason for the relatively weak erosion on Xiangluwan(XL)beach was the smaller beach berm height(accounting for approximately 75.9%of the erosion response).Regarding the beach with a higher berm,the stronger wave-induced undertow flow,along with the higher sediment concentration,led to a higher offshore sediment transport flux,resulting in more severe erosion relative to the beach with a smaller berm *** second most important reason explaining the weak erosion on XL beach was the absence of seawalls(accounting for approximately 17.9%of the erosion response).Wave reflection induced by the seawall could cause higher suspended sediment concentration,resulting in a toe scouring near the *** offshore submerged breakwater protected XL beach slightly(accounting for approximately 6.1%of the erosion response).Due to the higher water level induced by storm surge,most of the wave energy could penetrate through the submerged *** effect of the larger berm width of XL beach was *** to the beach with a larger berm width,the erosion/deposition regions in the beach with a narrower berm width showed shoreward migration,without significant changes in the erosion/deposition *** of this,the larger berm width could reduce the wave energy reaching the *** study of the storm stability of artificial beaches may be applied to beach restoration design.

关键词： beach erosion berm height berm width seawall fully nonlinear Boussinesq wave model(FUNWAVE)

Effect of short-time low-temperature austenitizing on microstructure and mechanical properties of DT300 ultra-high strength steel fabricated by laser powder bed fusion

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Journal of Iron and Steel Research(International) 2024年第7期31卷 1763-1777页

作者： Chen-yang Jiang Xiao-qiang Li Jin-tao wang Hao Luo Sheng-qing Gao Sheng-guan Qu chao Yang National Engineering Research Centre of Near-Net-Shape Forming for Metallic Materials South China University of TechnologyGuangzhou 510640GuangdongChina Institute of New Materials Guangdong Academy of ScienceGuangzhou 510650GuangdongChina

To address the inhomogeneous microstructure and improve the mechanical properties of DT300 ultra-high strength steel specimens fabricated by laser powder bed fusion,different post-heat treatment schedules are *** the increase in austenitizing temperature and time,the migration rate of austenite grain boundaries continuously increases with the dissolution of nano-carbides,and the formation of nano-oxides and twin martensite is also inhibited *** rapid growth in the size of prior austenite grains and martensite laths,as well as the decrease in the content of nano-oxides and twin martensite,led to a rapid decrease in the strength(yield strength and ultimate tensile strength)from HT2 to HTF *** HT1 specimens(austenitizing at 830℃for 30 min,then oil quenching and tempering at 300℃for 120 min and finally air cooling)display excellent mechanical properties of yield strength of 1572 MPa,ultimate tensile strength of 1847 MPa,elongation of 9.84%,and fracture toughness of 106 MPa m^(1/2),which are counterparts to those of conventional DT300 steel forgings after heat treatment.

关键词： DT300 ultra-high strength steel Laser powder bed fusion-Short-time low-temperature austenitizing Microstructure Mechanical property

Designing Proportional-Integral Consensus Protocols for Second-Order Multi-Agent Systems Using Delayed and Memorized State Information

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IEEE/CAA Journal of Automatica Sinica 2024年第4期11卷 878-892页

作者： Honghai wang qing-Long Han the College of Information Science and Engineering State Key Laboratory of Synthetical Automation for Process IndustriesNortheastern UniversityShenyang 110819China the School of Science Computing and Engineering TechnologiesSwinburne University of TechnologyMelbourneVIC 3122Australia

This paper is concerned with consensus of a secondorder linear time-invariant multi-agent system in the situation that there exists a communication delay among the agents in the network.A proportional-integral consensus protocol is designed by using delayed and memorized state *** the proportional-integral consensus protocol,the consensus problem of the multi-agent system is transformed into the problem of asymptotic stability of the corresponding linear time-invariant time-delay *** that the location of the eigenvalues of the corresponding characteristic function of the linear time-invariant time-delay system not only determines the stability of the system,but also plays a critical role in the dynamic performance of the *** this paper,based on recent results on the distribution of roots of quasi-polynomials,several necessary conditions for Hurwitz stability for a class of quasi-polynomials are first *** allowable regions of consensus protocol parameters are *** necessary and sufficient conditions for determining effective protocol parameters are *** designed protocol can achieve consensus and improve the dynamic performance of the second-order multi-agent ***,the effects of delays on consensus of systems of harmonic oscillators/double integrators under proportional-integral consensus protocols are ***,some results on proportional-integral consensus are derived for a class of high-order linear time-invariant multi-agent systems.

关键词： Consensus protocol Hurwitz stability multi-agent systems quasi-polynomials time delay