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A shake table investigation of dynamic behavior of pile supported bridges in liquefiable soil deposits

Earthquake Engineering and Engineering Vibration 2021年第1期20卷 1-24页

作者： Piyush Mohanty xu dan Suryakant Biswal Subhamoy Bhattacharya CSIR-Central Building Research Institute Roorkee247667India Fluor Ltd. 140 Pinehurst RoadFarnboroughGU147BFUK Institute of Engineering Mechanics China Earthquake AdministrationSanhe 065201China University of Surrey GuildfordGU27XHUK

Bridges are a part of vital infrastructure,which should operate even after a disaster to keep emergency services *** have been numerous bridge failures during major past earthquakes due to *** other categories of failures,mid span collapse(without the failure of abutments)of pile supported bridges founded in liquefiable deposits are still observed even in most recent *** mechanism of collapse is attributed to the effects related to the differential elongation of natural period of the individual piers during liquefaction.A shake table investigation has been carried out in this study to verify mechanisms behind midspan collapse of pile supported bridges in liquefiable *** this investigation,a typical pile supported bridge is scaled down,and its foundations pass through the liquefiable loose sandy soil and rest in a dense gravel *** noise motions of increasing acceleration magnitude have been applied to initiate progressive liquefaction and to characterize the dynamic features of the *** has been found that as the liquefaction of the soil sets in,the natural frequency of individual bridge support is reduced,with the highest reduction occurring near the central *** a result,there is differential lateral displacement and bending moment demand on the *** has also been observed that for the central pile,the maximum bending moment in the pile will occur at a higher elevation,as compared to that of the interface of soils of varied stiffness,unlike the abutment *** practical implications of this research are also highlighted.

关键词： bridges midspan failure liquefaction bridge collapse earthquake pile shake table test natural frequency

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Stellar dynamical modeling-accuracy of 3D density estimation for edge-on axisymmetric galaxies

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Research in Astronomy and Astrophysics 2021年第6期21卷 403-423页

作者： Richard J.Long Sheng-Dong Lu dan-dan xu Department of Astronomy Tsinghua UniversityBeijing 100084China Jodrell Bank Centre for Astrophysics Department of Physics and AstronomyThe University of ManchesterOxford RoadManchester M139PLUK

From Rybicki’s analysis using the Fourier slice theorem,mathematically it is possible to reproduce uniquely an edge-on axisymmetric galaxy’s 3D light distribution from its 2D surface *** galaxies from a cosmological simulation,we examine the ability of Syer and Tremaine’s madeto-measure method and Schwarzschild’s method for stellar dynamical modeling to do so for edge-on oblate axisymmetric ***,we find that the methods do not accurately recover the 3D distributions,with the made-to-measure method producing more accurate estimates than Schwarzschild’s *** results have implications broader than just luminosity density,and affect other luminosity-weighted distributions within galaxies,for example,age and metallicity.

关键词： galaxies:kinematics and dynamics galaxies:structure methods:numerical

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An enhanced least squares residual RAIM algorithm based on optimal decentralized factor

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Chinese Journal of Aeronautics 2020年第12期33卷 3369-3379页

作者： Guanghui SUN Chengdong xu dan SONG Yimei JIAN School of Aerospace Engineering Beijing Institute of TechnologyBeijing 100081China School of Electronic and Information Engineering Beihang UniversityBeijing 100191China

The Least Squares Residual(LSR)algorithm is commonly used in the Receiver Autonomous Integrity Monitoring(RAIM).However,LSR algorithm presents high Missed Detection Risk(MDR)caused by a large-slope faulty satellite and high False Alert Risk(FAR)caused by a small-slope faulty *** this paper,the LSR algorithm is improved to reduce the MDR for a large-slope faulty satellite and the FAR for a small-slope faulty *** on the analysis of the vertical critical slope,the optimal decentralized factor is defined and the optimal test statistic is conceived,which can minimize the FAR with the premise that the MDR does not exceed its allowable value of all three *** construct a new test statistic approximating to the optimal test statistic,the Optimal Decentralized Factor weighted LSR(ODF-LSR)algorithm is *** new test statistic maintains the sum of pseudo-range residual squares,but the specific pseudo-range residual is weighted with a parameter related to the optimal decentralized *** new test statistic has the same decentralized parameter with the optimal test statistic when single faulty satellite exists,and the difference between the expectation of the new test statistic and the optimal test statistic is the minimum when no faulty satellite *** performance of the ODFLSR algorithm is demonstrated by simulation experiments.

关键词： False alert Least squares residual(LSR)algorithm Missed detection Receiver autonomous integrity monitoring(RAIM) Slope

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Changes in the activities of key enzymes and the abundance of functional genes involved in nitrogen transformation in rice rhizosphere soil under different aerated conditions

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Journal of Integrative Agriculture 2023年第3期22卷 923-934页

作者： xu Chun-mei XIAO De-shun CHEN Song CHU Guang LIU Yuan-hui ZHANG Xiu-fu WANG dan-ying The State Key Laboratoty of Rice Biology China National Rice Research InstituteHangzhou 310006P.R.China

Soil microorganisms play important roles in nitrogen transformation. The aim of this study was to characterize changes in the activity of nitrogen transformation enzymes and the abundance of nitrogen function genes in rhizosphere soil aerated using three different methods(continuous flooding(CF), continuous flooding and aeration(CFA), and alternate wetting and drying(AWD)). The abundances of amoA ammonia-oxidizing archaea(AOA) and ammonia-oxidizing bacteria(AOB), nirS, nirK, and nifH genes, and the activities of urease, protease, ammonia oxidase, nitrate reductase, and nitrite reductase were measured at the tillering(S1), heading(S2), and ripening(S3) stages. We analyzed the relationships of the aforementioned microbial activity indices, in addition to soil microbial biomass carbon(MBC) and soil microbial biomass nitrogen(MBN), with the concentration of soil nitrate and ammonium nitrogen. The abundance of nitrogen function genes and the activities of nitrogen invertase in rice rhizosphere soil were higher at S2 compared with S1 and S3 in all treatments. AWD and CFA increased the abundance of amoA and nifH genes, and the activities of urease, protease, and ammonia oxidase, and decreased the abundance of nirS and nirK genes and the activities of nitrate reductase and nitrite reductase, with the effect of AWD being particularly strong. During the entire growth period, the mean abundances of the AOA amoA, AOB amoA, and nifH genes were 2.9, 5.8, and 3.0 higher in the AWD treatment than in the CF treatment, respectively, and the activities of urease, protease, and ammonia oxidase were 1.1, 0.5, and 0.7 higher in the AWD treatment than in the CF treatment, respectively. The abundances of the nirS and nirK genes, and the activities of nitrate reductase and nitrite reductase were 73.6, 84.8, 10.3 and 36.5% lower in the AWD treatment than in the CF treatment, respectively. The abundances of the AOA amoA, AOB amoA, and nifH genes were significantly and positively correlated wi

关键词： rhizosphere aeration gene abundance enzyme activities soil microbial biomass carbon soil microbial nitrogen

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Performance of Convective Parameterization Schemes in Asia Using RegCM:Simulations in Three Typical Regions for the Period 1998–2002

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Advances in Atmospheric Sciences 2015年第5期32卷 715-730页

作者： Shaukat ALI dan Li fu Congbin YANG Yang START Temperate East Asia Regional Center and Key Laboratory of Regional Climate-Environment for Temperate East Asia Institute of Atmospheric Physics Chinese Academy of Sciences University of Chinese Academy of Sciences Global Change Impact Studies Centre Ministry of Climate Change

This study discusses the sensitivity of convective parameterization schemes（CPSs） in the Regional Climate Model（version 4.3）（Reg CM4.3） over East/South Asia. The simulations using different CPSs in Reg CM are compared to discover a suitable scheme for this region, as the performance of different schemes is greatly influenced by region and seasonality. Over Southeast China and the Bay of Bengal, the Grell scheme exhibits the lowest RMSEs of summer precipitation compared to observed data. Moreover, the Emanuel over land and Grell over ocean（ELGO） scheme enhances the simulation, in comparison with any single CPS（Grell/Emanuel） over Western Ghats, Sri Lanka, and Southeast India. Over the Huang–Huai–Hai Plain（3H） and Tibetan Plateau（TP） regions of China, the Tiedtke scheme simulates the more reasonable summer precipitation with high correlation coefficient and comparable amplitude. Especially, it reproduces a minimum convective precipitation bias of 8 mm d^-1and the lowest RMSEs throughout the year over East/South Asia. furthermore, for seasonal variation of precipitation, the Tiedtke scheme results are closer to the observed data over the 3H and TP regions. However, none of the CPSs is able to simulate the seasonal variation over North Pakistan（NP）. In comparison with previous research, the results of this study support the Grell scheme over South Asia. However, the Tiedtke scheme shows superiority for the 3H, TP and NP regions. The thicker PBL, less surface latent heat flux, the unique ability of deep convection and the entrainment process in the Tiedtke scheme are responsible for reducing the wet bias.

关键词： regional climate models(RCM) Reg CM4 Tiedtke scheme convective parameterization scheme(CPS) topography seasonality

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The shape optimization of the arterial graft design by level set methods

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Applied Mathematics(A Journal of Chinese Universities) 2016年第2期31卷 205-218页

作者： JIANG Dong HAN dan-fu HU Xian-liang School of Mathematical Sciences Zhejiang University Department of Mathematics Hangzhou Normal University

The goal of the arterial graft design problem is to find an optimal graft built on an occluded artery, which can be mathematically modeled by a fluid based shape optimization problem. The smoothness of the graft is one of the important aspects in the arterial graft design problem since it affects the flow of the blood significantly. As an attractive design tool for this problem, level set methods are quite efficient for obtaining better shape of the graft. In this paper, a cubic spline level set method and a radial basis function level set method are designed to solve the arterial graft design problem. In both approaches, the shape of the arterial graft is implicitly tracked by the zero-level contour of a level set function and a high level of smoothness of the graft is achieved. Numerical results show the efficiency of the algorithms in the arterial graft design.

关键词： Arterial graft Shape optimization Level set method Adjoint variable method.

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Conceptual understandings of the ecological engineering issues in China and abroad

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Journal of Environmental Sciences 2000年第2期12卷 78-83页

作者： xu, fu-Liu Tao, Shu Departemnt of Urban and Environemmal Sciences Peking University Beijing 100871 China

The research on ecological engineering has been lasting for more than four decades. As a new, cheaper, environmentally acceptable and alternative techniques, ecological engineering has been applied to many aspects, including ecoagricultural engineering, ecosystem restoration, environmental conservation, and pollution control. This paper presents a conceptual understanding on the issues of ecological engineering, including its origin, concepts, goals, principles and applications.

关键词： ecological engineering ecologist engineer CLC number: X171 4 Document code: A

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Adaptive NN Dynamic Surface Control for a Class of Uncertain Non-affine Pure-feedback Systems with Unknown Time-delay

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International Journal of Automation and computing 2016年第3期13卷 268-276页

作者： Xiao-Qiang Li dan Wang Zhu-Mu fu Information Engineering College Henan University of Science and Technology Marine Engineering College Dalian Maritime University

Adaptive neural network （NN） dynamic surface control （DSC） is developed for a class of non-affine pure-feedback systems with unknown time-delay. The problems of ＂explosion of complexity＂ and circular construction of the practical controller in the traditional backstepping algorithm are avoided by using this controller design method. For removing the requirements on the sign of the derivative of function f~, Nussbaum control gain technique is used in control design procedure. The effects of unknown time-delays are eliminated by using appropriate Lyapunov-Krasovskii functionals. Proposed control scheme guarantees that all the signals in the closed-loop system are semi-globally uniformly ultimately bounded. Two simulation examples are presented to demonstrate the method.

关键词： Nonaffine pure-feedback systems dynamic surface control (DSC) time-delay neural network backstepping.

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Asymptotic Behavior of Impulsive Stochastic functional Differential Equations

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Acta Mathematica Sinica,English Series 2014年第6期30卷 1061-1072页

作者： Li Guang xu dan Hua HE Department of Applied Mathematics Zhejiang University of Technology Department of Mathematics Zhejiang International Studies University

In this paper, a nonlinear and nonautonomous impulsive stochastic functional differential equation is considered. By establishing a nonautonomous -operator impulsive delay inequality and using the properties of ρ-cone and stochastic analysis technique, we obtain the p-attracting set and p-invariant set of the impulsive stochastic functional differential equation. An example is also discussed to illustrate the efficiency of the obtained results.

关键词： p-attracting set p-invariant set -operator inequality stochastic impulsive

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Syntax theory of finite lattice-valued propositional logic

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Science China(Information Sciences) 2013年第8期56卷 177-188页

作者： PAN XiaoDong MENG dan xu Yang School of Mathematics Southwest Jiaotong University Intelligent Control Development Center Southwest Jiaotong University School of Economics Information Engineering Southwestern University of Finance and Ecnomics

In this paper,we establish the graded syntax theory of lattice-valued propositional logic based on finite lattice implication algebras,define the notions of syntactic consequence operation and formal proof,and develop a kind of graded finite lattice-valued propositional *** generalizing classic provable equivalence relation,we present a kind of generalized provable equivalence relation,and establish the corresponding quotient ***,we establish the generalized deduction theorem by syntactic consequence operation,and establish the completeness in Pavelka’s sense based on finite chains.

关键词： Lattice-valued propositional logic syntax theory inference rule generalized deduction theorem completeness

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