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Optimization of N18 Zirconium Alloy for Fuel Cladding of Water Reactors

Journal of Materials Science & Technology 2012年第7期28卷 606-613页

作者： B.x. Zhou M. Y. Yao Z.K. li x.M. Wang J. Zhoua C.S. Long Q. liu B.F. Luan Laboratory for Mierostructures Shanghai University Shanghai 200444 China Institute of Materials Shanghai University Shaxighai 200072 China Northwest Institute for Non-ferrous Metal Research Xian 721014 China Key Laboratory for Nuclear Fuel and Materials Nuclear Power Institute of China Chengdu 610041 China College of Material Science and engineering Chongqing University Chongqing 400044 China

In order to optimize the microstructure and composition of N18 zirconium alloy （Zr-1Sn-0.35Nb-0.35Fe-0.1Cr, in mass fraction, %）, which was developed in China in 1990s, the effect of microstructure and composition variation on the corrosion resistance of the N18 alloy has been investigated. The autoclave corrosion tests were carried out in super heated steam at 400 ~C/10.3 MPa, in deionized water or lithiated water with 0.01 mol/L liOH at 360 ~C/18.6 MPa. The exposure time lasted for 300-550 days according to the test temperature. The results show that the microstructure with a fine and uniform distribution of second phase particles （SPPs）, and the decrease of Sn content from 1% （in mass fraction, the same as follows） to 0.8% are of benefit to improving the corrosion resistance; It is detrimental to the corrosion resistance if no Cr addition. The addition of Nb content with upper limit （0.35%） is beneficial to improving the corrosion resistance. The addition of Cu less than 0.1% shows no remarkable influence upon the corrosion resistance for N18 alloy. Comparing the corrosion resistance of the optimized N18 with other commercial zirconium alloys, such as Zircaloy-4, ZIRLO, e635 and ell0, the former shows superior corrosion resistance in all autoclave testing conditions mentioned above. Although the data of the corrosion resistance as fuel cladding for high burn-up has not been obtained yet, it is believed that the optimized N18 alloy is promising for the candidate of fuel cladding materials as high burn-up fuel assemblies. Based on the theory that the microstructural evolution of oxide layer during corrosion process will affect the corrosion resistance of zirconium alloys, the improvement of corrosion resistance of the N18 alloy by obtaining the microstructure with nano-size and uniform distribution of SPPs, and by decreasing the content of Sn and maintaining the content of Cr is discussed.

关键词： Zirconium alloys Corrosion resistance Composition variation Microstructure

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Variational Boundary Conditions for Molecular Dynamics Simulations of Solids at Low Temperature

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Communications in Computational Physics 2006年第1期1卷 135-175页

作者： xiantao li Weinan e Department of Mathematics Pennsylvania State UniversityUniversity ParkPA 16802USA Department of Mathematics&Program in Applied and Computational Mathematics Princeton UniversityPrincetonNJ 08544USA

Boundary conditions for molecular dynamics simulation of crystalline solids are considered with the objective of eliminating the reflection of phonons.A variational formalism is presented to construct boundary conditions that minimize total phonon *** boundary conditions that involve a few neighbors of the boundary atoms and limited number of time steps are found using the variational *** effects are studied and compared with other boundary conditions such as truncated exact boundary conditions or by appending border atoms where artificial damping forces are *** general it is found that,with the same cost or complexity,the variational boundary conditions perform much better than the truncated exact boundary conditions or by appending border atoms with empirical damping *** issues of implementation are discussed for real *** to brittle fracture dynamics is illustrated.

关键词： Boundary condition molecular dynamics phonon reflection crack propagation

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Set stability for switched Boolean networks with open-loop and closed-loop switching signals

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Science China(Information Sciences) 2018年第9期61卷 232-240页

作者： xiaohua li Jianquan LU Jianlong QIU xiangyong CHeN xiaodi li Fuad e.ALSAADI School of Automation and engineering and Key Laboratory of Complex Systems and Intelligent Computing in Universities of Shandong Linyi University School of Mathematics and Statistics Shandong Normal University School of Mathematics Southeast University Department of electrical and Computer engineering King Abdulaziz University

This paper mainly analyzes the set stability of switched Boolean networks(SBNs) by considering two different methods of switching signals in the form of open-loop and closed-loop switching. First, the definitions of set stability are proposed for SBNs with such switching signals. Then, we propose two different algorithms to find the largest open-loop switching invariant set and largest closed-loop switching invariant set. Furthermore, the corresponding set stability conditions for SBNs are given in each case. In addition,the constructive procedures are presented to design the switching signal sequence to achieve set stability under the two different methods of switching signals. Finally, the effectiveness of the proposed algorithms and research results are demonstrated using two numerical examples.

关键词： switched Boolean network set stability semi-tensor product switching signal design

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Red-emitting CaWO4:eu^(3+),Tm^(3+)phosphor for solid-state lighting:Luminescent properties and morphology evolution

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Journal of Rare earths 2022年第2期40卷 226-233,I0002页

作者： L.x.Lovisa I.M.P.da Silva A.A.G.Santiago M.Siu li e.Longo C.A.Paskocimas M.R.D.Bomio F.V.Motta Institute of Physics and Chemistry.Federal University of Itajubd(UNIFeI) ItajubdMG37500-903Brazil LSQM-Laboratory of Chemical Synthesis of Materials-Department of Materials engineering Federal University of Rio Grande Do NorteP.O.Box 152459078-900Natal RNBrazil IFSC USPAv.Trabalhador Sao Carlense400CEP 13566-590Sao CarlosSPBrazil CDMF-lieC UFSCarP.O.Box 67613565-905Sao Carlos.SPBrazil

CaWO_(4):xeu^(3+),yTm^(3+)crystals were obtained by facile synthesis at low temperature by the microwaveassisted hydrothermal method(MAH).The phase formation,morphology,luminescent properties and ene rgy transfer were *** x-ray diffraction(xRD)re sults show the formation of a scheelitelike tetragonal structure without the presence of secondary *** growth mechanism of hierarchical micro structures based on self-assembly and Ostwald-ripening processes was evaluated,obtaining different types of *** luminescence spectra of CaWO_(4):eu^(3+),Tm^(3+)at 325 nm excitation show the predominance of red emission at the 5 D0→7 F2(eu^(3+))transition at 624 *** feature signals dominant behavior of the electric dipole *** presence of Tm^(3+)is notably evident in the absorption spectra by the related excitation transitions:3 H6→1 G4,3 H6→3 F3 and 3 H6→3 *** parameters are discussed to characterize CaWO_(4):eu^(3+),Tm^(3+)*** study of the emission spectrum as a function of the concentration of eu^(3+)(x mol%)and Tm^(3+)(y mol%)indicates that the CaWO_(4):eu^(3+),Tm^(3+)phosphors show stronger red emission intensity and exhibit the CIe value of x=0.63 and y=*** photoluminescence results show 97%high color purity for CaWO_(4):4 mol%eu^(3+),a high CRI(92%)and a low CCT of 1085 *** results demonstrate that the CaWO_(4):eu^(3+),Tm^(3+)red phosphors are promising as color converters for application in white light-emitting diodes and display devices.

关键词： CaWO_(4):eu^(3+),Tm^(3+)microwave-assisted hydrothermal method Photoluminescence Red phosphor Rare earths

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New fossils of the early Pleistocene equus huanghoensis(equidae,Perissodactyla)from Nihewan in Hebei Province of China

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Science China earth Sciences 2016年第10期59卷 83-94页

作者： li Yongxiang ZHANG Yunxiang SUN BoYang AO Hong xUe xiangxu State Key Laboratory of Continental Dynamics Department of GeologyNorthwest UniversityXi'an 710069China State Key Laboratory of Loess and Quaternary Geology Institute of Earth EnvironmentChinese Academy of SciencesXi'an 710061China Tianjin Museum of Natural History Tianjin 300201China

This paper describes new fossils of equus huanghoensis from an early Pleistocene bed in Nihewan, Hebei Province, which confirms the classification of e. huanghoensis by Chinese researchers. The new fossils include a relatively complete male skull and mandible with all upper and lower dentition, a broken female skull with fragment of mandible and a broken Mc III of equus sp. The fossils were collected from the Yangshuizhan site of Nihewan. The age of the formation is about 1.6 Ma. The new materials verify some classification characteristics based on teeth published in previous descriptions. These characteristics include large teeth size, short protocone, and tilted protoloph and metaloph. We have added to these characteristics of large skull size, a developed protuberantia supramagna, pentagonal nuchal side, weak Pli cabaline, simple enamel plications; a series of new characteristics strikingly different from the other equus horses. The broken Mc III is similar to equus qingyangensis from Qingyang, Gansu.

关键词： Nihewan early Pleistocene equus huanghoensis New fossils

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Stability of a Variable Coefficient Star-Shaped Network with Distributed Delay

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Journal of Systems Science & Complexity 2022年第6期35卷 2077-2106页

作者： ZHANG Hai-e xU Gen-Qi CHeN Hao li Min School of Mathematics Tianjin UniversityTianjin 300350China Department of Basic Science Tangshan UniversityTangshan 063000China School of Mechatronical engineering Beijing Institute of TechnologyBeijing 100081China

The paper deals with the exponential stability problem of a variable coefficient star-shaped network,whose strings are coupled at a common end in a star-shaped configuration and the common connection of all strings can be *** kinds of media materials with a component of viscous and another simply elastic are distributed on each *** suitable hypothesis on the coefficient functionsμj(x)of damping terms and the kernelsηj(s)of distributed delay terms,the well-posedness of the system is obtained by means of resolvent family *** addition,the allocation proportion of the two parts and the property of the material character functions are discussed when the starshaped network is exponentially ***,the sufficient condition of exponential stability is *** simulations are also included to verify the main results.

关键词： Allocation proportion elastic and viscous exponential stability resolvent family starshaped network

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Quantifying cold front induced water transport of a bay with in situ observations using manned and unmanned boats

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Acta Oceanologica Sinica 2018年第11期37卷 1-7页

作者： WeeKS eddie ROBINSON Mark e li Chunyan Coastal Studies Institute Department of Oceanography and Coastal Sciences Louisiana State University Department of Geography and Anthropology Louisiana State University

The generation of high-resolution data is increasingly important in understanding the complexities of coastal ocean and developing sound management strategies, especially in view of the long-term impact of severe weather systems. The impact of severe weather systems, when integrated over time, can be significant when compared with tidal oscillations. This paper presents a study of water transport out of Vermilion Bay in response to a short, intense event associated with a passing atmospheric cold front, and reports the application of an Acoustic Doppler Current Profiler （ADCP） mounted on an Automated Surface Craft （ASC）, known as the auto-boat or unmanned boat, developed in our lab at the Louisiana State University, to generate high resolution data accurately at a fraction of the cost of a manned boat. In our study, we used a manned boat and an unmanned boat, each for over 24 h to cover an entire diurnal tidal cycle, to measure flow velocity profiles to calculate the total transport. A stationary ADCP was deployed in the Southwest Pass of the Vermilion Bay from May 2009 to April 2012, providing data almost continuously （with only one major gap）, with a 717-day record of water transport between the northern Gulf of Mexico and Vermilion Bay, and demonstrates the importance of the pass in water transport.

关键词： cold fronts unmanned boat Vermillion Bay Acoustic Doppler Current Profiler surveys regression on transport

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A Wind Tunnel experimental Study on the Wake Characteristics of a Horizontal Axis Wind Turbine

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Journal of Thermal Science 2025年第1期 145-158页

作者： GUO xingduo li Yinran li Rennian MA Yulong WeI Kui College of energy and Power engineering Lanzhou University of Technology Key Laboratory of Fluid Machinery and Systems Gansu Provincial Technology Centre for Wind Turbines

The characteristics of wind turbine wakes are influenced by multiple factors,including the atmospheric boundary layer(ABL) wind and wind turbine operating conditions(e.g.,tip speed ratio and yaw angle).In this study,two types of ABL winds with different velocity gradients and turbulence intensities are generated in a wind tunnel through configurations of spires,baffles,and various numbers of roughness elements.A wind turbine with a rotor diameter of 0.8 m and a hub height of 0.6 m is tested under varying tip speed ratios,yaw angles,and ABL wind *** results indicate that the streamwise velocity deficit in the near-wake region becomes more pronounced with an increase in the tip speed ratio,while the far-wake velocity deficit remains largely unaffected by changes in the tip speed *** the yaw angle increases,the wake deflection becomes more prominent and the wake narrows;the offset of the wake center at various downstream positions grows linearly,reaching a maximum value of approximately half the rotor ***,the turbulence level and influence range in the wake region are reduced when the turbine is *** ABL wind conditions,high turbulence intensity in the incoming flow accelerates wake recovery,and the Reynolds stress at different lateral positions tends to become consistent with increasing longitudinal ***,turbulence has a significant impact on the meandering characteristics of the wind turbine wake,with greater fluctuations in the wake center observed under higher turbulence ***,this study provides insights that could inform the optimal operation of wind farms.

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Root Morphology and Zn^2＋ Uptake Kinetics of the Zn Hyperaccumulator of Sedum alfredii Hance

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Journal of Integrative Plant Biology 2005年第8期47卷 927-934页

作者： Ting-Qiang li xiao-e YANG Zhen-li He Jin-Yan YANG Ministry of education Key Laboratory of environmental Remediation and ecosystem Health Zhejiang University Huajiachi Campus Hangzhou 310029 China University of Florida Indian River Research and Education Center Fort Pierce Florida 34945 USA

Root morphology and Zn^2＋ uptake kinetics of the hyperaccumulating ecotype （He） and nonhyperaccumulating ecotype （NHe） of Sedum alfredii Hance were investigated using hydroponic methods and the radiotracer flux technique. The results indicate that root length, root surface area, and root volume of NHe decreased significantly with increasing Zn^2＋ concentration in growth media, whereas the root growth of He was not adversely affected, and was even promoted, by 500μmol/L Zn^2＋. The concentrations of Zn^2＋ in both ecotypes of S. alfredii were positively correlated with root length, root surface area and root volumes, but no such correlation was found for root diameter. The uptake kinetics for ^65Zn^2＋ in roots of both ecotypes of S. alfredii were characterized by a rapid linear phase during the first 6 h and a slower linear phase during the subsequent period of investigation. The concentration-dependent uptake kinetics of the two ecotypes of S. alfredii could be characterized by the Michaelis-Menten equation, with the Vmax for ^65Zn^2＋ influx being threefold greater in He compared with NHe, indicating that enhanced absorption into the root was one of the mechanisms involved in Zn hyperaccumulation. A significantly larger Vmax value suggested that there was a higher density of Zn transporters per unit membrane area in He roots.

关键词： phytoremediation Sedum alfredii translocation uptake kinetics zinc (Zn).

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effectiveness of Implicit Methods for Stiff Stochastic Differential equations

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Communications in Computational Physics 2008年第2期3卷 295-307页

作者： Tiejun li Assyr Abdulle Weinan e LMAM and School of Mathematical Sciences Peking UniversityBeijing 100871China School of Mathematics and Maxwell Institute for Mathematical Sciences King’s BuildingsEdinburghEH93JZUK Department of Mathematics and PACM Princeton UniversityPrincetonNJ 08544USA.

In this paper we study the behavior of a family of implicit numerical methods applied to stochastic differential equations with multiple time *** show by a combination of analytical arguments and numerical examples that implicit methods in general fail to capture the effective dynamics at the slow time *** is due to the fact that such implicit methods cannot correctly capture non-Dirac invariant distributions when the time step size is much larger than the relaxation time of the system.

关键词： Implicit methods stiff ODe stiff SDe invariant distribution multiscale.

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