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Extreme storm surge induced coastal inundation in Yangtze Estuary regions

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Journal of Hydrodynamics 2019年第6期31卷 1127-1138页

作者： Zhen-hua Pan hua liu Key Laboratory of Hydrodynamics(Ministry of Education) School of Naval ArchitectureOcean and Civil EngineeringShanghai Jiao Tong UniversityShanghai 200240China DHI China Shanghai 200235China

Coastal inundation induced by the storm surge belongs to one of the major natural hazards in Shanghai and other regions around the Yangtze *** worst scenarios of coupling the extreme storm and the sea level rise are presented to assess the storm surge hazard in the Yangtze *** numerical model MIKE 21 FM is adopted to implement the numerical study,which includes wind,current,tide and *** storm surge induced by typhoon 9711 is simulated,and the measurements of six tide gauges are used to validate the numerical *** identify the worst case scenario of severe typhoon(9711)and super typhoon(5612),we propose seven typhoon tracks through the Yangtze Estuary and fourteen scenarios of landfall time for each typhoon track,which generates 196 ***,based on the worst case scenario and the relative sea level rise in the range of 0 m to 0.7 m,the coastal inundation maps of Pudong New District and Changxing Island are provided and discussed.

关键词： Storm surge inundation Yangtze Estuary sea level rise numerical simulation

Quantitative deformation measurements and analysis of the ferrite-austenite banded structure in a 2205 duplex stainless steel at 250 ℃

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Chinese Physics B 2018年第3期27卷 487-493页

作者： Ji-hua liu School of Mechanical Engineering Tianjin UniversityTianjin 300354China Tianjin Key Laboratory of Modern Engineering Mechanics Tianjin UniversityTianjin 300354China

The deformation process of the microstructure in 2205 duplex stainless steel(DSS)under thermo-mechanical coupling at 250℃was investigated using digital image correlation(DIC).A thermal tension test of duplex stainless steel(2205DSS)with a banded structure was carded out to observe the initial deformation of the *** was found that inhomogeneous strain fields occurred primarily in *** maximum normal strain in austenite was almost pos-itive,while that in ferrite was almost *** addition,a thermal cyclic-loading test was conducted,and the strain field was characterized by *** heterogeneities were induced after 400 cycles,which spread within the austenite and at the phase boundaries with the load *** high tensile-strain regions were always located adjacent to regions of intense compressive *** on the strain matrix sum *** number,we found that hardening occurred in the early cycles followed by softening.

关键词： thermo-mechanical coupling duplex stainless steel digital image correlation(DIC)

Effect of a viscoelastic target on the impact response of a flat-nosed projectile

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Acta Mechanica Sinica 2018年第1期34卷 162-174页

作者： Hu liu Jialing Yang hua liu Institute of Solid Mechanics Beihang University

Taylor impact is a widely used strategy in which a flat-nosed projectile is fired onto a rigid anvil directly to determine the dynamic strength of rod specimens. Nowadays, the rigid anvil is often replaced by an output target bar to ensure the accuracy of measurement via recording strain signals in the output bar. For testing the dynamic strength of low-density materials, a low-impedance target bar, which exhibits viscoelastic characteristics is often employed. In this paper, an extended Taylor model is proposed to improve the idealization of treating the target bar as perfectly rigid material in the classic Taylor model, and the viscoelastic effect of the target bar is incorporated. The viscoelastic target bar is depicted by two elastic springs and one dashpot. Based on the plastic shock wave theory in the flat-nosed projectile associated with the viscoelastic wave analysis in the target bar, the viscoelastic effect of the target bar on the impact response of the flat-nosed projectile is investigated. The finite element simulation is also carried out to verify the theoretical model,and good agreement is found. The present theoretical model is also called the Taylor-cylinder Hopkinson impact, which provides a more accurate way to identify the dynamic material parameters. The dynamic responses of the present model are further compared with previous elastic and rigid target bar models. It is found that the viscoelastic effect of the target bar should be taken into consideration in the Taylor-cylinder Hopkinson impact test for low-impedance materials.

关键词： Dynamic response Taylor impact Viscoelastic target Low-density material

Halo-like Structures Observed in ^(209)Pb

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Chinese Physics Letters 2001年第8期18卷 1024-1026页

作者： liu Zu-hua China Institute of Atomic Energy Beijing 102413

The density distributions of the last neutron in ^(209)Pb wereinvestigated by analysis of the ^(208)Pb(d,p)^(209)Pb transfer reactions at 8 *** results show that the last neutron in the 2d_(5/2),3s_(1/2),1g_(7/2) and 2d_(3/2) states is present with appreciable probability at distances much larger than the core ***,these states should be the neutron halo or skin ***,the density distributions extracted illustrate that there is intrinsic relationship between the node number of state and the halo formation.

关键词： formation. states. radius.

Microstructure evolution in large billet during reduction pretreatment based on laboratory experiments

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Journal of Iron and Steel Research International 2023年第6期30卷 1244-1257页

作者： Yang liu Jian-hua liu Yang He National Engineering Research Center for Advanced Rolling and Intelligent Manufacturing University of Science and Technology BeijingBeijing 100083China

The reduction pretreatment process has been proposed to improve the center quality of large billet and reduce the rolling *** microstructure evolution during the reduction pretreatment was further *** austenite grains were refined after the reduction pretreatment experiment,especially those at the center of the *** effects of strain and strain rate on the average grain size were dependent on the deformation *** a strain rate of 0.01 s-1 and 1200°C,the newly formed strain-free austenite grains grew very fast as the strain continued to increase,which resulted in the coarsening of austenite *** calculation results of the microstructure evolution model showed that at the same deformation temperature,the evolution curves of average grain size with different strain rates had the intersection *** the increase in temperature,the position of intersection point moved to the downward direction of *** simulation results showed that when the reduction amount increased to 20%,the average grain size at the center was smaller than that near the *** could be inferred that when the reduction amount greatly exceeded 20%,the dynamic recrystallization at the center was mostly completed,and the austenite grain growth would become the main mechanism.

关键词： Large billet Reduction pretreatment Dynamic recrystallization Grain refinement Microstructure evolution model

Prospects for Variable Gauge Rolling:Technology,Theory and Application

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Journal of Iron and Steel Research International 2011年第1期18卷 1-7页

作者： liu Xiang-hua Northeastern University Shenyang 110004 Liaoning China

Variable gauge rolling （VGR） is a new technology to produce flat products with different thicknesses （FDT）, which could be used to replace conventional fiat products in order to save metals and reduce structure mass. The method of VGR was introduced for investigating new problems in rolling theory of VGR, and the new formulas for calculating parameters of VGR were proposed. Besides, some results of numerical simulation by finite elemen~ method were described. As an example, the products applications of FDT in bridge construction, ship building and auto manufacturing were presented. Finally, the prospects for VGR and FDT were discussed.

关键词： variable gauge rolling longitudinal profile plate tailor rolled blank

Investigating distance halo effect of fixed automated speed camera based on taxi GPS trajectory data

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Journal of Traffic and Transportation Engineering(English Edition) 2023年第1期10卷 70-85页

作者： Chuanyun Fu hua liu School of Transportation Science and Engineering Harbin Institute of TechnologyHarbin 150090China Department of Civil Engineering University of British ColumbiaVancouver V6T 1Z4Canada School of Transportation Southeast UniversityJiangsu 211189China

Background:The deterrence effect of automated speed camera(ASC)is still ***,it is pointed out that ASC may have varying deterrence effects on different types of road users(e.g.,taxis).Objective:This study intends to investigate the distance halo effect of fixed ASC(hereafter called ASC)on ***:More than 1.34 million taxis’GPS trajectory data were collected.A novel indicator,the delta speed(defined as the difference between the traveling speed and the speed limit),was proposed to continuously describe the variations in traveling *** upstream and downstream critical delta speeds during each time period on weekdays and weekends were obtained by using K-means clustering method,*** on the critical delta speeds,the ranges of upstream and downstream distance halo effects of ASC during different time periods on weekdays and weekends were determined separately and ***:The downstream critical delta speed is smaller than the upstream *** upstream and downstream distance halo effects of ASC on taxis are within a range of 8-2180 m and an area of 10-580 m to the ASC location,*** are no obvious difference in the ranges of upstream and downstream distance halo effects of ASC on taxis between different time periods or between weekdays and ***:The present study confirms that the upstream and downstream distance halo effects of ASC on taxis have different ranges and the stabilities of time-of-day and *** application:The findings of this study can provide a basic reference for reasonably deploying ASCs within a region.

关键词： Distance halo effect Automated speed camera Critical delta speed K-means clustering GPS trajectory data

A VERTICAL 2-D NUMERICAL SIMULATION OF SUSPENDED SEDIMENT TRANSPORT

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Journal of Hydrodynamics 2007年第2期19卷 217-224页

作者： ZHANG Jing-xin liu hua Department Of Engineering Mechanics Shanghai Jiaotong University Shanghai 200240 China

Numerical simulation of sediment transport and bed evolution has become an important technique in the sediment research. In this article, a numerical model of suspended sediment transport was proposed, which was established in the vertical σ coordinate for fitting the free surface and bottom. In the research of the sediment transport, the predominant factors were found to be the eddy diffusion, the settling velocity, the bed condition and so on. By the aid of the model in the article, the contribution of the Rouse parameter to the vertical profile of sediment concentration was clarified, which was identical to the theoretical results. In the comparison of the numerical results with laboratory data, the agreement between experimental data and numerical results was reached except for some data. And the possible reasons for the disagreement were discussed.

关键词： suspended sediment transport 2-D numericalmodel σ coordinate

Impulse-coupling coefficients from a pulsed-laser ablation of semiconductor GaAs

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Nuclear Science and Techniques 2006年第4期17卷 217-221页

作者： liu Ai-hua College of Physics and Electronics Shandong Normal University Jinan 250014 China

Impulse-coupling coefficients from 1.06 - μ m, 10-ns Nd:YAG pulsed-laser radiation to GaAs targets with different areas were measured using the ballistic pendulum method in the laser power density ranging from 4.0 × 108 to 5.0 × 109 W·cm-2. A detonation wave model of the plasma was established theoretically. The expansion process of plasma after the laser pulse ends is described in detail, and the impulse-coupling coefficients from pulsed laser with different energies to GaAs with different areas were calculated using the given model. It is found that the theoretical results agree well with the experimental data.

关键词：激光-材料相互作用冲击式联接镓砷半导体激光爆破