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LARGE TIME BEHAVIOR OF THE 1D ISENTROPIC NAVIER-STOKES-POISSON SYSTEM

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Acta Mathematica Scientia 2022年第5期42卷 1843-1874页

作者： Qingyou HE jiawei sun Department of Mathematics Capital Normal UniversityBeijing 100048China Department of Mathematics Shandong Normal UniversityJinan 250014China

The initial value problem(IVP)for the one-dimensional isentropic compressible Navier-Stokes-Poisson(CNSP)system is considered in this *** the variables,the electric field and the velocity,under the Lagrange coordinate,we establish the global existence and uniqueness of the classical solutions to this IVP *** we prove by the method of complex analysis,that the solutions to this system converge to those of the corresponding linearized system in the L^(2) norm as time tends to *** addition,we show,using Green’s function,that the solutions to this system are close to a diffusion profile,pointwisely,as time goes to infinity.

关键词： 1D Navier-Stokes-Poisson system well-posedness L^(2)-time decay rates timespace pointwise behaviors

Local Discontinuous Galerkin Methods for the abcd Nonlinear Boussinesq System

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Communications on Applied Mathematics and Computation 2022年第2期4卷 381-416页

作者： jiawei sun Shusen Xie Yulong Xing Department of Mathematics The Ohio State UniversityColumbusOH 43210USA School of Mathematical Sciences Ocean University of ChinaQingdao 266100ShandongChina

Boussinesq type equations have been widely studied to model the surface water *** this paper,we consider the abcd Boussinesq system which is a family of Boussinesq type equations including many well-known models such as the classical Boussinesq system,the BBM-BBM system,the Bona-Smith system,*** propose local discontinuous Galerkin(LDG)methods,with carefully chosen numerical fluxes,to numerically solve this abcd Boussinesq *** main focus of this paper is to rigorously establish a priori error estimate of the proposed LDG methods for a wide range of the parameters a,b,c,*** experiments are shown to test the convergence rates,and to demonstrate that the proposed methods can simulate the head-on collision of traveling wave and finite time blow-up behavior well.

关键词： Local discontinuous Galerkin methods Boussinesq equations Coupled BBM equations Error estimate Numerical fluxes Head-on collision

Deformation Behavior and Microstructure Evolution of AA2024-H18 Aluminum Alloy by Hot Forming with Synchronous Cooling Operations

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Transactions of Nanjing University of Aeronautics and Astronautics 2017年第5期34卷 504-513页

作者： Chen Guoliang Chen Minghe Wang Ning sun jiawei College of Mechanical and Electrical Engineering Nanjing University of Aeronautics and Astronautics Nanjing 210016 P.R. China Changzhou Institute of Mechatronic Technology Changzhou 213164 P.R. China

Hot forming with synchronous cooling(HFSC)is a novel technique for heat-treatable,high-strength aluminum alloys,which allows the alloys to acquire good formability,negligible springback,rapid processing and better mechanical ***,the deformation behavior and microstructure evolution of the alloys during HFSC are complex and need to be studied due to the temperature and strain rate *** tensile tests in a temperature range of 250—450℃and a strain rate range of 0.01—1 s-1 for AA2024-H18 aluminum alloy sheet are conducted with a Gleeble-3500 Thermal-Mechanical Simulation *** based on metallography observation and analysis,AA2024-H18 aluminum alloy sheet in HSFC process exhibits hardening and dynamic recovery behaviors within the temperature range of 250—450 ℃.Strain rate shows different effects on ductility at different *** with traditional warm/hot forming methods,AA2024-H18 aluminum alloy achieves a better work-hardening result through HFSC operations,which promises an improved formability at elevated temperature and thus good mechanical properties of final *** HSFC operations,the microstructure of the specimens is composed of elongated static recrystallization grain.

关键词： hot forming with synchronous cooling AA2024 aluminum alloy deformation behavior microstructure evolution

Optimization of confined aquifer dewatering for long-deep excavation using simulation–optimization method

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Underground Space 2024年第4期17卷 246-266页

作者： Yanxiao sun Zhenxiong Jiang Liyuan Tong jiawei sun Jia Cui Xin Zhou Songyu Liu Institute of Geotechnical Engineering Southeast UniversityNanjing 211189China Nanjing Modern Multimodal Transportation Laboratory Nanjing 211100China Jiangsu Provincial Transportation Construction Bureau Nanjing 210004China

The confined aquifer dewatering for long-deep excavations usually encounters challenges due to complicated geotechnical conditions,large excavation sizes,and high hydraulic *** propose the most efficient scheme of confined aquifer dewatering for long-deep excavations,dewatering optimizations were performed using the simulation–optimization *** open cut tunnel of the Jiangyin-Jingjiang Yangtze River Tunnel Project was taken as an *** methods of finite element and linear programming(LP)were combined to optimize the dewatering process.A three-dimensional finite element model was *** simulating the pumping tests,hydraulic conductivity was ***,necessary parameters in the LP method were determined by simulating dewatering with each pumping well,and various LP models were developed based on some important influence factors such as dewatering sequence,considered pumping wells,and pumping rate ***,the optimal pumping rates were solved and applied to the numerical model,with induced drawdown and ground settlement computed for *** results indicate that the optimization can significantly reduce the required wells in the original *** in the deepest zone exhibits the highest efficiency for long-deep excavations with gradually varying *** the dewatering sequence from the shallowest to the deepest zone,more pumping wells are required but less energy is *** quantity and more advantageous locations of pumping wells in the LP model usually result in lower total pumping rate,drawdown,and ground *** more pumping wells are considered in the deepest zone,pumping rate limitation of single well will only slightly increase the total pumping rate,number of required pumping wells,drawdown,and ground settlement.

关键词： Dewatering Confined aquifer Simulation-optimization Linear programming Open cut tunnel

Integration of chemical and biological methods:A case study of polycyclic aromatic hydrocarbons pollution monitoring in Shandong Peninsula,China

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Journal of Environmental Sciences 2022年第1期34卷 24-37页

作者： Zeyuan Li Yunhao Cao Huawei Qin Yuanqing Ma Luqing Pan jiawei sun Key Laboratory of Mariculture Ministry of EducationOcean University of ChinaQingdao 266003China Shandong Marine Resources and Environment Research Institute Yantai 264006China

Polycyclic aromatic hydrocarbons(PAHs),as persistent toxic substances(PTS),have been widely monitored in coastal environment,including seawater and ***,scientific monitoring methods,like ecological risk assessment and integrated biomarker response,still need massive researches to verify their *** study was performed in March,May,August and October of 2018 at eight sites,Yellow River estuary(S1),Guangli Port(S2),Xiaying(S3),Laizhou(S4),Inner Bay(S5),Outer Bay(S6),Hongdao(S7)and Hongshiya(S8)of Shandong Peninsula,*** contents of 16 priority PAHs in local seawater and sediment were determined,by which ecological risk assessment risk quotient(RQ)for seawater and sediment quality guidelines(SQGs)were calculated to characterize the PAHs ***,multiple biomarkers in the digestive gland of clam Ruditapes philippinarum were measured to represent different biological endpoints,including ethoxyresorufin-O-deethylase(EROD),glutathione S-transferase(GST),sulfotransferase(SULT),superoxide dismutase(SOD)and lipid peroxidation(LPO),by which integrated biomarker response(IBR)was calculated to provide a comprehensive assessment of environmental *** together,these results revealed the heaviest pollution at S2 as both PAHs concentrations and biomarkers responses reflected,and supported the integrated biomarker response as a useful tool for marine environmental monitoring,through its integration with SQGs.

关键词： Shandong Peninsula Polycyclic aromatic hydrocarbons(PAHs) Ruditapes philippinarum Risk quotient Sediment quality guidelines Integrated biomarker response

Strength and elastic modulus enhancement in Mg-Li-Al matrix composites reinforced by ex situ TiB2 particles via stir casting

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Journal of Magnesium and Alloys 2024年第9期12卷 3574-3588页

作者： jiawei sun Dehua Ding Wencai Liu Guohua Wu Hongjie Liu Guangling Wei Hezhou Liu National Engineering Research Center of Light Alloy Net Forming and State Key Laboratory of Metal Matrix Composites School of Materials Science and EngineeringShanghai Jiao Tong UniversityShanghai 200240China

A novel Mg^(-1)0Li-3Al(wt.%,LA103)matrix composite reinforced by ex situ micron TiB_(2) particles was developed in the present *** ball milling and cold pressing pretreatment of the reinforcements made it feasible to prepare this material under stir casting conditions with good *** microstructure and mechanical properties of the composites prepared by different pretreatment methods were analyzed in *** TiB_(2) particles in the Al-TiB_(2)/LA103 composite using the pretreatment process were uniformly distributed in the microstructure due to the formation of highly wettable core-shell units in the *** with the matrix alloys,the Al-TiB_(2)/LA103 composite exhibited effective strength and elastic modulus improvements while maintaining acceptable *** strengthening effect in the composites was mainly attributed to the strong grain refining effect of *** work shows a balance of high specific modulus(36.1 GPa·cm^(3)·g^(-1))and elongation(8.4%)with the conventional stir casting path,which is of considerable application value.

关键词： Mg-Li composite Stir casting Elastic modulus Microstructure Mechanical properties

Data-Driven Rogue Waves in Nonlocal PT-Symmetric Schr?dinger Equation via Mix-Training PINN

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Journal of Systems Science & Complexity 2024年

作者： sun jiawei LI Biao School of Mathematics and Statistics Ningbo University

In this paper, by modifying loss function MSE(adding the mean square error of the complex conjugate term to the loss function) and training area of the physics-informed neural network(PINN), the authors proposed two neural network models: Mix-training PINN and prior information mix-training PINN. The authors demonstrated the advantages of these models by simulating rogue waves in the nonlocal PT-symmetric Schr?dinger equation. Numerical experiments showed that the proposed models not only simulate first-order rogue waves, but also significantly improve the simulation capability. Compared with original PINN, the prediction accuracy of the first-order rouge waves are improved by one to three orders of magnitude. By testing the inverse problem of first-order rogue waves, it is also proved that these models have good performance.

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Microstructure evolution and enhanced fatigue behavior in the Mg-10Li-5Zn-0.5Er alloys micro-alloyed with Yb

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Journal of Magnesium and Alloys 2024年第8期12卷 3159-3172页

作者： Guanglan Liao Guohua Wu Wencai Liu jiawei sun Lv Xiao Song Pang Peijun Chen National Engineering Research Center of Light Alloy Net Forming and State Key Laboratory of Metal Matrix Composite School of Materials Science and EngineeringShanghai Jiao Tong UniversityShanghai 200240China Shanghai Spaceflight Precision Machinery Institute Shanghai 201600China Shanghai Engineering Technology Research Center of Near-Net-Shape Forming for Metallic Materials Shanghai 201600China Luoyang Shengya Magnesium Alloy Technology Co. LtdLuoyang 471921China

In this paper,(0.2-1 wt%)Yb was added to improve the tensile properties and high-cycle fatigue behavior of the as-cast and as-extruded Mg-10Li-5Zn-0.5Er *** is found that Yb mainly affects the mechanical properties of the alloy by changing the grain size,type and morphology of the second *** mainly exists in the formation of Mg_(2)Yb and Mg-Zn-Yb phases in the metallographic *** the addition of Yb,the grains are refined and these Yb-containing phases replace the large-sized MgLiZn phase to be enriched at the grain *** the addition of excess Yb reduces the number of small-sized MgLiZn phases in the grain,thus reducing the alloys’mechanical *** extrusion,the small-sized MgLiZn phase is refined and the number increases,which effectively improves the tensile and fatigue strength of the *** fatigue strength is mainly affected by the number and morphology of the second phase,positively correlated with the *** in grain size and number and size of second phases,the extruded alloy with 0.2Yb added exhibits excellent mechanical properties with the yield strength,ultimate tensile strength and elongation of 292 MPa,303 MPa and 11.7%,and an fatigue strength of 130 MPa.

关键词： Mg-Li alloy Yb Microstructure Fatigue property Hot extrusion

Integrated Optimization of Storage Allocations in Automated Storage and Retrieval System of Bearings

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Integrated Optimization of Storage Allocations in Automated ...