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Design and construction of super-long span bridges in China: Review and future perspectives

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Frontiers of Structural and Civil Engineering 2020年第4期14卷 803-838页

作者： wei HUANG Minshan PET Xiaodong LIU ya wei Intelligent Transportation System Research Center Southeast UniversityNanjing 211189China China Communications Construction Company Ltd. Beijing 100088China Department of Civil Engineering Tsinghua UniversiyBeijing 100084China

Super-long span bridges demand high design requirements and involve many difficulties when constructed,which is an important indicator to reflect the bridge technical level of a *** the past three decades,a large percentage of the new long-span bridges around the world were built in China,and thus,abundant technological innovations and experience have been accumulated during the design and *** paper aims to review and summarize the design and construction practices of the superstructure,the substructure,and the steel deck paving of the long-span bridges during the past decades as well as the current operation status of the existing long-span bridges in China.A future perspective was given on the developing trend of high-speed railway bridge,bridge over deep-sea,health monitoring and maintenance,intellectualization,standard system,and information technology,which is expected to guide the development direction for the construction of future super long-span bridges and promote China to become a strong bridge construction country.

关键词： long-span bridges steel box girder design technology construction technology,review and future perspectives

Top-down control on major groups of global marine diazotrophs

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Acta Oceanologica Sinica 2022年第8期41卷 111-119页

作者： Hua Wang ya-wei Luo State Key Laboratory of Marine Environmental Science Xiamen UniversityXiamen 361102China College of Ocean and Earth Sciences Xiamen UniversityXiamen 361102China

Dinitrogen(N_(2))fixed by a group of prokaryotes(diazotrophs)is the dominant process adding bioavailable nitrogen into the *** it has been intensively studied how N_(2) fixation is controlled by resources(bottom-up factors),it is unclear whether the grazing(top-down control)effectively impacts growth and distribution of different diazotroph *** this study,we evaluate this question by conducting log-log regression of diazotroph biomass onto corresponding N_(2) fixation rates in the global *** slope of the regression for Trichodesmium is~0.8,indicating that a small portion of the increase in N_(2) fixation does not accumulate as its *** leads to a conclusion that Trichodesmium is under a substantial top-down control,although bottom-up control still *** also analyze the residuals of the regression in the North Atlantic,concluding that free trichomes of Trichodesmium are subject to stronger top-down control than its *** weak correlation between the biomass and N_(2) fixation of unicellular cyanobacterial diazotrophs indicates that the degree of top-down control on this type of diazotrophs varies *** analyses obtain unrealistic results for diatom-diazotroph assemblages due to complicated nitrogen sources of these *** study reveals the variability of top-down control among different diazotroph groups across time and space,suggesting its importance in improving our understandings of ecology of diazotrophs and predictions of N_(2) fixation in biogeochemical *** of size-specific N_(2) fixation rates and growth rates of different diazotroph groups can be useful to more reliably analyze the top-down control on these key organisms in the global ocean.

关键词： marine diazotrophs nitrogen fixation top-down control bottom-up control Trichodesmium diatom-diazotroph assemblages

Dislocation Movement in Nitrogen-Doped Czochralski Silicon

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Chinese Physics Letters 1996年第5期13卷 382-385页

作者： wei ya-dong LIANG Jun-wu Department of Physics Shanxi UniversityTaiyuan 030006 Institute of Semiconductors Chinese Academy of SciencesBeijing 100083

Dislocation movemnent in N-doped Czochralski silicon(Cz-Si)was surrveyed by four point bend method,Dislocation mnovemnent velocities ***-Si doped with nitrogen,with both nitrogen and antimony,and with only antimony were investigated,The order of measured dislocation movement velocities,at 700℃≤T≤800℃ and under resolved stress σ=4.1 kg/mm^(2),was Vsp,O>V_(N,sb,O)>V_(N,O).The experiments showed that nitrogen doping could retard the movement ofdislocations.

关键词： Dislocation stress movement

Valley switch effect in anα-T3 lattice-based superconducting interferometer

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Chinese Physics B 2024年第11期33卷 372-377页

作者： ya-Jun wei Jun Wang School of Physics Southeast UniversityNanjing 210096China

Dirac electrons possess a valley degree of freedom,which is currently under investigation as a potential information *** propose an approach to generate and manipulate the valley-switching current(VSC)through Andreev reflection using an interferometer-based superconductor hybrid *** interferometer comprises a ring-shaped structure formed by topological kink states in the a-T3 lattice via carefully designed electrostatic *** results demonstrate the feasibility of achieving a fully polarized VSC in this device without contamination from cotunneling electrons sharing the same valley as the incident ***,we show that control over the fully polarized VSC can be achieved by applying a nonlocal gate voltage or modifying the global parameter *** former alters the dynamic phase of electrons while the latter provides an a-dependent Berry phase,both directly influencing quantum interference and thereby affecting performance in terms of generating and manipulating VSC,crucial for advancements in valleytronics.

关键词： valley switch effect valleytronics Andreev reflection a-T3 lattice

Simulating Alpine Vegetation Net Primary Productivity by Remote Sensing in Qinghai Province,China

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Journal of Mountain Science 2014年第4期11卷 967-978页

作者： wei ya-xing WANG Li-wen Center for Marine Economic and Sustainable Development Liaoning Normal University Liaoning Key Laboratory of Physical Geography and Geomatics Liaoning Normal University College of Urban and Environmental Science Liaoning Normal University

Primary productivity of ecosystem is important indicator about ecological assessment. Remote sensing technology has been used to monitor net primary productivity （NPP） of ecological system for several years. In this paper, the remotely sensed NPP simulation model of alpine vegetation in Qinghai Province of Tibet Plateau was set up based on the theory of light use efficiency. Firstly a new approach based on mixed pixels and Support Vector Machine （SVM） algorithm were used to correct simulated NPP values derived from Moderate Resolution Imaging Spectroradiometer （MODIS） data. Finally, spatial distribution and monthly variation characteristics of NPP in Qinghai Province detail. The result showed in 2006 were analyzed in that NPP of vegetation in Qinghai Province in 2006 ranged from o to 422 gC/m2/a and the average NPP was 151 gC/m2/a. NPP gradually increased from northwest to southeast. NPP of different vegetation types were obviously different. The average NPP of broad-leaved forest was the largest （314 gC/m2/a）, and sparse shrub was the smallest （101 gC/m2/a）. NPP in Qinghai Province significantly changed with seasonal variation. The accumulation of NPP was primarily in the period （from April to September） with better moist and heat conditions. In July, the average NPP of vegetation reached the maximum value （43 gC/m2）. In our model, the advantage of traditional LUE models was adopted, and our study fully considered typicalcharacteristics of alpine vegetation light use efficiency and environmental factors in the study area. Alpine vegetation is the most important ecological resource of Tibet Plateau, exactly monitoring its NPP value by remote sensing is an effective protection measure.

关键词： Net primary productivity Remotesensing Light use efficiency model Contexturalapproach Support Vector Machine

An enhanced treatment of boundary conditions in implicit smoothed particle hydrodynamics

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Acta Mechanica Sinica 2014年第1期30卷 37-49页

作者： ya-wei Han Hong-Fu Qiang Hu Liu wei-Ran Gao Xi’an Research Inst.of Hi-Tech.

In this work, an enhanced treatment of the solid boundaries is proposed for smoothed particle hydrodynamics with implicit time integration scheme （Implicit SPH）. Three types of virtual particles, i.e., boundary particles, image particles and mirror particles, are used to impose boundary conditions. Boundary particles are fixed on the solid boundary, and each boundary particle is associated with two fixed image particles inside the fluid domain and two fixed mirror particles outside the fluid domain. The image particles take the flow properties through fluid particles with moving least squares （MLS） interpolation and the properties of mirror particles can be obtained by the corresponding image particles. A repulsive force is also applied for boundary particles to prevent fluid particles from unphysical penetra- tion through solid boundaries. The new boundary treatment method has been validated with five numerical examples. All the numerical results show that Implicit SPH with this new boundary-treatment method can obtain accurate results for non-Newtonian fluids as well as Newtonian fluids, and this method is suitable for complex solid boundaries and can be easily extended to 3D problems.

关键词： Implicit SPH. Boundary conditions. Power-law model Repulsive force MLS interpolation

Direct synthesis of diaryl sulfides by copper-catalyzed coupling of aryl halides with aminothiourea

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Chinese Chemical Letters 2012年第4期23卷 391-394页

作者： Xiang Mei Wu wei ya Hu Department of Chemistry College of ScienceLishui UniversityLishui 323000China

An efficient and simple protocol of copper-catalyzed C-S bond formation between aryl halides and inexpensive and commercially available aminothiourea is reported.A variety of symmetrical diaryl sulfides can be synthes... 详细信息

关键词： Copper Diaryl sulfide Aryl halide Aminothiourea

Reaction of titanium investment castings made by Zr(CH3COO)2-Y2O3 shell

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Rare Metals 2017年第6期36卷 465-471页

作者： Xin Guo ya-Meng wei Zhi-Gang Lu Department of Mechanical Engineering Tsinghua UniversityBeijing 100084 China Academy of Opto-Electronics Chinese Academy of SciencesBeijing 100094 China State Key Laboratory of Tribology Tsinghua UniversityBeijing 100084 China

The forming process and mechanism of the reaction of Ti-6Al-4V investment casting made by Zr（CH3COO）2-Y2O3 shell in vacuum casting was *** was manipulated to study the distributions and types of the reaction layers. The morphology and composition of the reaction layers were tested using field emission scanning electron microscopy（FESEM） combined with energy-dispersive spectroscopy（EDS）. Phase of the reaction layers was characterized by X-ray diffraction（XRD）.Composition of the shell reaction zone was measured by X-ray fluorescence（XRF） method. The results suggest the reaction contains oxidation and element evaporation, and the melt reacts little with the shell but mainly with the remnant gas. The reaction layers contain three types due to different forming stages： the titanium oxidation film, the concretion film and the shell reaction zone. The interfacial temperature and pressure affect the reaction mechanism and degree, leading to three types of concretion films that differ in thickness, content and color.

关键词： Titanium alloy Investment casting Reaction Oxidation Element evaporation

Effect of wide-spectrum pulsed magnetic field on grain refinement of pure aluminium

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China Foundry 2023年第1期20卷 40-48页

作者： ya-ming Bai Gang Li ya-wei Sun Yong-yong Gong Qi-jie Zhai College of Science Shanghai University99 Shangda RoadShanghai 200444China Center for Advanced Solidification Shanghai University99 Shangda RoadShanghai 200444China School of Materials Science and Engineering Shanghai University99 Shangda RoadShanghai 200444China

A wide-spectrum pulsed magnetic field(WSPMF)was obtained by adjusting the number of current pulses and the pulse interval between adjacent *** effect of WSPMF on the grain refinement of pure aluminium was *** distribution of electromagnetic force and flow field in the melt under the WSPMF was simulated to reveal the grain refining *** show that the grain refinement is attributed to the combined effect of the melt flow and oscillation under a *** the pulse interval is 5 ms,the extreme value of electromagnetic force is the highest,and the size of the crystal nucleus is 0.35 *** the case of similar flow rates,the grain size gradually decreases as the pulse interval *** range of the harmonic frequency of the magnetic field gradually expands with the increase of the pulse interval,which can provide more energy for nucleation at the solid-liquid interface and promote nucleation.

关键词： wide-spectrum pulsed magnetic field forced flow grain refinement frequency components