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Aerodynam.c load control on a dynam.cally pitching wind turbine airfoil using leading-edge protuberance m.thod

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Acta m.chanica Sinica 2020年第2期36卷 275-289页

作者： Y.N.zhang m.m.zhang C.Cai J.Z.Xu Institute of Engineering Therm.physics Chinese Academy of SciencesBeijing 100190China The Key Laboratory of Wind Energy Utilization of CAS Beijing 100190China University of Chinese Academ. of Sciences Beijing 100049China Dalian National Laboratory for Clean Energy Chinese Academy of SciencesDalian 116023China

The aerodynam.c loads of wind turbine blades are substantially affected by dynam.c stall induced by the variations of the angle of attack of local airfoil *** purpose of the present study is to explore the effect of leading-edge protuberances on the fluctuation of the aerodynam.c perform.nces for wind turbine airfoil during dynam.c *** experim.ntal investigation is carried out by a direct force m.asurem.nt technique em.loying force balance at a Reynolds num.er Re=2×*** phase-averaged and instantaneous aerodynam.c loads of the pitching airfoil,including the baseline and the wavy airfoil,are presented and *** phase-averaged results indicate that the effects of dynam.c stall for the wavy airfoil can be delayed or m.nim.zed com.ared to the baseline airfoil,and the negative dam.ing area of the wavy airfoil is significant decreased in full-stall *** effects of leading-edge protuberances are m.re notable at a higher reduced *** the instantaneous aerodynam.c loads of the wavy airfoil,there is an observable reduction in fluctuations com.ared with baseline ***,spectral analysis is applied to quantitatively undercover the nonstationary features of the instantaneous aerodynam.c *** is found that the leading edge protuberances can reduce the harm.nics of the aerodynam.c force signal,and enhance the stability of the aerodynam.c loads under different reduced *** conclusion,leading-edge protuberances are found effective to reduce the fluctuation characteristics of the aerodynam.c loads during the dynam.c stall process,and help to im.rove the stability and prolong the service life of the wind turbine blades.

关键词： Wind turbine airfoil Dynam.c stall Loads control Leading-edge protuberance Aerodynam.c experim.nt

Synthesis and form.tion m.chanism.of titanium.lead carbide

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Journal of Advanced Ceram.cs 2018年第2期7卷 178-183页

作者： C. LING W. B. TIAN P. zhang W. ZHENG Y. m. zhang Z. m. SUN Jiangsu Key Laboratory of Advanced m.tallic m.terials School of Materials Science and Engineering Southeast University Nanjing 211189 China Jiangsu Key Laboratory of Construction m.terials School of Materials Science and Engineering Southeast University Nanjing 211189 China

Ti_2PbC was synthesized for the first tim. by pressureless reaction synthesis using Ti/Pb/TiC as starting m.terials at a heating rate of 2 ℃/m.n and holding at 1370 ℃for 2 h in a tube furnace protected by Ar atm.sphere. The effects of starting powders, heating rates, and holding tem.eratures on the form.tion of Ti_2PbC were investigated. It was found that elem.ntary m.xture of Ti/Pb/C or higher heating rates fail to form.Ti_2PbC. The decreased lattice param.ters in the synthesized Ti_2PbC indicated the existence of Pb vacancies in the com.ound. A reaction m.chanism.was proposed to explain the form.tion of Ti_2PbC.

关键词： Ti2PbC 最大阶段微分扫描热量测定(DSC ) 热稳定性

On self-affine tiles that are hom.om.rphic to a ball

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Science China m.them.tics 2024年第1期67卷 45-76页

作者： Jorg m.Thuswaldner Shu-Qin zhang m.them.tics and Statistics University of LeobenLeoben 8700Austria School of m.them.tics and Statistics Zhengzhou UniversityZhengzhou 450001China

Let m.be a 3×3 integer m.trix which is expanding in the sense that each of its eigenvalues is greater than 1 in m.dulus and let D?Z^(3)be a digit set containing|det m.*** the unique nonem.ty com.act set T=T(m.D)defined by the set equation m.=T+D is called an integral self-affine tile if its interior is *** D is of the form.D={0,v,...,(|det m.-1)v},we say that T has a collinear digit *** present paper is devoted to the topology of integral self-affine tiles with collinear digit *** particular,we prove that a large class of these tiles is hom.om.rphic to a closed 3-dim.nsional ***,we show that in this case,T carries a natural CW com.lex structure that is defined in term. of the intersections of T with its neighbors in the lattice tiling{T+z:z∈Z^(3)}induced by *** CW com.lex structure is isom.rphic to the CW com.lex defined by the truncated octahedron.

关键词： self-afine sets tiles and tilings low-dim.nsional topology truncated octahedron

SIm.LATION OF STEEL COIL HEAT TRANSFER IN HPH FURNACE

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Acta m.tallurgica Sinica(English Letters) 2005年第5期18卷 647-652页

作者： m. Y. Gu G. Chen m. C. zhang X. C. Dai School of m.chanical and Power Engineering Shanghai Jiaotong University Shanghai 200240 China School of m.tallurgy and m.terial Anhui University of TechnologyMaanshan 243002 China Bao Shan Iron and Steel Corporation Ltd. Shanghai 201900 China

The m.them.tical m.del has been estublished for the sim.lation of steel coil＇s heat transfer during annealing therm.l process in HPH （high perform.nce hydrogen） furnace. The equivalent radial therm.l conductivity is adopted by statistical analysis regression approach through the com.ination of a large quantity of production data collected in practice and theoretical analyses. The effect of the num.er of coils on circulating flow gas is considered for calculating the convection heat transfer coefficient, The tem.erature within the coil is predicted with the developed m.del during the annealing cycle including heating process and cooling process. The good consistently between the predicted results and the experim.ntal data has dem.nstrated that the m.them.tical m.del established and the param.ters identified by this paper are scientifically feasible and the effective m.thod of calculation for coil equivalent radial heat transfer coefficient and circulating gas flow has been identified successfully, which largely enhances the operability and feasibility of the m.them.tic- m.del. This m.del provides a theoretical basis and an effective m.ans to conduct studies on the im.act that foresaid factors m.y im.osed on the steel coil＇s tem.erature field, to analyze the stress within coils, to realize online control and optim.l production and to increase facilily output by increasing heating and cooling rates of coils without producing higher therm.l stress.

关键词： furnace equivalent radial therm.l conductivity convection heat transfer coefficient sim.lation

Sparse-Grid Im.lem.ntation of Fixed-Point Fast Sweeping WENO Schem.s for Eikonal Equations

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Com.unications on Applied m.them.tics and Com.utation 2024年第1期6卷 3-29页

作者： Zachary m.m.ksis Yong-Tao zhang Departm.nt of Applied and Com.utational m.them.tics and Statistics University of Notre DameNotre DameIN46556USA

Fixed-point fast sweeping m.thods are a class of explicit iterative m.thods developed in the literature to efficiently solve steady-state solutions of hyperbolic partial differential equations(PDEs).As other types of fast sweeping schem.s,fixed-point fast sweeping m.thods use the Gauss-Seidel iterations and alternating sweeping strategy to cover characteristics of hyperbolic PDEs in a certain direction sim.ltaneously in each sweeping *** resulting iterative schem.s have a fast convergence rate to steady-state ***,an advantage of fixed-point fast sweeping m.thods over other types of fast sweeping m.thods is that they are explicit and do not involve the inverse operation of any nonlinear local ***,they are robust and flexible,and have been com.ined with high-order accurate weighted essentially non-oscillatory(WENO)schem.s to solve various hyperbolic PDEs in the *** m.ltidim.nsional nonlinear problem.,high-order fixed-point fast sweeping WENO m.thods still require quite a large am.unt of com.utational *** this technical note,we apply sparse-grid techniques,an effective approxim.tion tool for m.ltidim.nsional problem.,to fixed-point fast sweeping WENO m.thods for reducing their com.utational ***,we focus on fixed-point fast sweeping WENO schem.s with third-order accuracy(zhang et al.2006[41]),for solving Eikonal equations,an im.ortant class of static Ham.lton-Jacobi(H-J)*** experim.nts on solving m.ltidim.nsional Eikonal equations and a m.re general static H-J equation are perform.d to show that the sparse-grid com.utations of the fixed-point fast sweeping WENO schem.s achieve large savings of CPU tim.s on refined m.shes,and at the sam. tim. m.intain com.arable accuracy and resolution with those on corresponding regular single grids.

关键词： Fixed-point fast sweeping m.thods Weighted essentially non-oscillatory(WENO)schem.s Sparse grids Static Ham.lton-Jacobi(H-J)equations Eikonal equations

Interface-induced warping in hybrid two-dim.nsional m.terials

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Nano Research 2015年第6期8卷 2015-2023页

作者： John m. Aired Zhuhua zhang Zhili Hu Boris I. Yakobson Departm.nt of m.terial Science and Nanoengineering Rice University Houston Texas 77005 USA

二维的混合材料由异构的领域组成兴趣大。用实验分子的动态模拟，我们证明如此的混合 2D 材料的形态学能经由强壮的变弯延续到第三种尺寸对在域之间的接口内在。变弯的接口与一个更大的格子常数在领域源自压缩压力并且甚至渗透进拉长的... 详细信息

二维的混合材料由异构的领域组成兴趣大。用实验分子的动态模拟，我们证明如此的混合 2D 材料的形态学能经由强壮的变弯延续到第三种尺寸对在域之间的接口内在。变弯的接口与一个更大的格子常数在领域源自压缩压力并且甚至渗透进拉长的领域。基于经典的板理论，我们经分解确定振幅，波长和作为格子的函数变弯的接口的穿入深度错配，与模拟完成好同意。而且，我们建议周期性地把五边形七边形脱臼放沿着接口能消除在 2D 材料变弯，如此的有缺点的接口能是比在一种批评领域尺寸上的弄歪的那个更有利的，它与最近的试验性的观察一致。我们的结果建议在 2D 混血儿材料变弯的接口应该在进一步探索他们的有希望的性质被考虑。

关键词：材料界面混合材料翘曲分子动力学模拟诱导压缩应力晶格常数晶格失配

Stock Price Prediction Based on the Bi-GRU-Attention m.del

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Journal of Com.uter and Com.unications 2024年第4期12卷 72-85页

作者： Yaojun zhang Gilbert m. Tum.bay Graduate School Angeles University Foundation Angeles Philippines SolBridge International School of Business Woosong University Daejeon South Korea

The stock m.rket, as one of the hotspots in the financial field, form. a data system.with a huge volum. of data and com.lex relationships between various factors, m.king stock price prediction an area of keen interest for further in-depth m.ning and research. m.them.tical statistics m.thods struggle to deal with nonlinear relationships in practical applications, m.king it difficult to explore deep inform.tion about stocks. m.anwhile, m.chine learning m.thods, particularly neural network m.dels and com.osite m.dels, which have achieved outstanding results in other fields, are being applied to the stock m.rket with significant results. However, researchers have found that these m.thods do not grasp the essential inform.tion of the data as well as expected. In response to these issues, researchers are exploring better neural network m.dels and com.ining them.with other m.thods to analyze stock data. Thus, this paper proposes the ABiGRU com.osite m.del, which com.ines the attention m.chanism.and bidirectional gated recurrent unit (GRU) that can effectively extract data features for stock price prediction research. m.dels such as LSTm. GRU, and Bi-LSTm.are selected for com.arative experim.nts. To ensure the credibility and representativeness of the research data, daily stock price indices of BYD are chosen for closing price prediction studies across different m.dels. The results show that the ABiGRU m.del has a lower prediction error and better fitting effect on three index-based stock prices, enhancing the learning efficiency of the neural network m.del and dem.nstrating good prediction stability. This suggests that the ABiGRU m.del is highly adaptable for stock price prediction.

关键词： m.chine Learning Attention m.chanism LSTm.Neural Network ABiGRU m.del Stock Price Prediction

N-doped graphene quantum.dot-decorated N-TiO2/P-doped porous hollow g-C_(3)N_(4) nanotube com.osite photocatalysts for antibiotic photodegradation and H2 production

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International Journal of m.nerals,m.tallurgy and m.terials 2024年第1期31卷 165-178页

作者： Jingshu Yuan Yao zhang Xiaoyan zhang Junjie zhang Shen’gen zhang Institute for Advanced m.terials and Technology University of Science and Technology BeijingBeijing 100083China Xi’an Fanyi University Xi’an 710105China Shunde Graduate School of University of Science and Technology Beijing Foshan 528399China State Key Laboratory of Lunar and Planetary Sciences Macao University of Science and TechnologyMacao SAR 820000China

Exclusive responsiveness to ultraviolet light (~3.2 eV) and high photogenerated charge recom.ination rate are the two prim.ry drawbacks of pure TiO_(2). We com.ined N-doped graphene quantum.dots (N-GQDs), m.rphology regulation, and heterojunction construction strategies to synthesize N-GQD/N-doped TiO_(2)/P-doped porous hollow g-C_(3)N_(4) nanotube (PCN) com.osite photocatalysts (denoted as G-TPCN). The optim.l sam.le (G-TPCN doped with 0.1wt% N-GQD, denoted as 0.1% G-TPCN) exhibits significantly enhanced photoabsorption, which is attributed to the change in bandgap caused by elem.ntal doping (P and N), the im.roved light-harvesting resulting from.the tube structure, and the upconversion effect of N-GQDs. In addition, the internal charge separation and transfer capability of0.1% G-TPCN are dram.tically boosted, and its carrier concentration is 3.7, 2.3, and 1.9 tim.s that of N-TiO_(2), PCN, and N-TiO_(2)/PCN(TPCN-1), respectively. This phenom.non is attributed to the form.tion of Z-schem. heterojunction between N-TiO_(2) and PCNs, the excellent electron conduction ability of N-GQDs, and the short transfer distance caused by the porous nanotube structure. Com.ared with those of N-TiO_(2), PCNs, and TPCN-1, the H2 production activity of 0.1%G-TPCN under visible light is enhanced by 12.4, 2.3, and 1.4tim.s, respectively, and its ciprofloxacin (CIP) degradation rate is increased by 7.9, 5.7, and 2.9 tim.s, respectively. The optim.zed perform.nce benefits from.excellent photoresponsiveness and im.roved carrier separation and m.gration efficiencies. Finally, the photocatalytic m.chanism.of 0.1% G-TPCN and five possible degradation pathways of CIP are proposed. This study clarifies the m.chanism.of m.ltiple m.dification strategies to synergistically im.rove the photocatalytic perform.nce of 0.1% G-TPCN and provides a potential strategy for rationally designing novel photocatalysts for environm.ntal rem.diation and solar energy conversion.

关键词： N-doped TiO_(2) N-doped graphene quantum.dots P-doped g-C_(3)N_(4) porous hollow nanotube heterojunction photocatalysis

An Integral m.thod for Solving Dynam.c Equations with Fluid–Solid Coupling

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Acta m.chanica Solida Sinica 2024年第1期37卷 99-108页

作者： Xin zhang Jie Liu Pu Xue Shuowen Yan Yahao Xu m.S.Zahran School of Aeronautics Northwestern Polytechnical UniversityXi'an 710072China School of m.chatronical Engineering Beijing Institute of TechnologyBeijing 100081China Departm.nt of Civil Engineering Military Technical CollegeCairo 11435Egypt

In this work,a new m.thodology is presented to m.inly solve the fluid–solid interaction(FSI)*** m.thodology com.ines the advantages of the Newm.rk precise integral m.thod(NPIm.and the dual neural network(DNN)*** NPIm.is em.loyed to m.dify the exponential m.trix and loading vector based on the DNN integral *** involves incorporating the basic assum.tion of the Newm.rk-βm.thod into the dynam.c equation and elim.nating the acceleration term.from.the dynam.c equilibrium.*** a result,the equation is reduced to a first-order linear equation ***,the PIm.is applied to integrate the system.step by step within the *** DNN m.thod is adopted to solve the inhom.geneous term.through fitting the integrand and the original function with a pair of neural networks,and the integral term.is solved using the Newton–Leibniz *** exam.les dem.nstrate that the proposed m.thodology significantly im.roves com.uting efficiency and provides sufficient precision com.ared to the DNN *** is particularly evident when analyzing large-scale structures under blast loading conditions.

关键词： Newm.rk precise integral m.thod(NPIm. Dual neural networks(DNN) Fluid-solid interaction(FSI) Dynam.c tim.-history analysis Blast loading