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Frontiers of Structural and Civil Engineering 2019年第1期13卷 92-102页

作者： Chung Nguyen VAN Department of Civil Engineering Faculty of EngineeringChulalongkorn UniversityThailand Faculty of Civil Engineering Ho Chi Minh City of Technology and EducationVietNam

The scaled boundary finite element method (SBFEM)is applied to the static analysis of two dimensional elasticity problem,boundary value problems domain with the domain completely described by a circular defining curve. The scaled boundary finite element equations is formulated within a general framework integrating the influence of the distributed body force,general boundary conditions,and bounded and unbounded *** paper investigates the possibility of using exact geometry to form the exact description of the circular defining curve and the standard finite element shape function to approximate the defining *** linear elasticity problems are presented to verify the proposed method with the analytical *** examples show the accuracy and efficiency of the proposed method,and the performance is found to be better than using standard linear element for the approximation defining curve on the scaled boundary method.

关键词： exact geometry circular defining curve general boundaries SBFEM

Effects of geometrical and physical factors on light particles dispersion by agitation characteristic curve

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Chinese Journal of Chemical Engineering 2019年第10期27卷 2313-2324页

作者： Meng Li Yangbo Tan Yufeng Liu Jianglong Sun De Xie Zeng Liu School of Naval Architecture and Ocean Engineering Huazhong University of Science and TechnologyWuhan 430074China Collaborative Innovation Center for Advanced Ship and Deep-Sea Exploration(CISSE) Shanghai 200240China Hubei Key Laboratory of Naval Architecture and Ocean Engineering Hydrodynamics(HUST) Wuhan 430074China

In this study,the effects of geometrical and physical factors on light particles dispersion in stirred tank were investigated by agitation characteristic *** experiments and CFD simulations with discrete phase model(DPM)and volume of fluid model(VOF)were conducted in this *** factors,which include four geometrical factors(submergence,impeller-to-tank ratio,number of impeller blades and baffling mode)and a physical factor(liquid viscosity)were *** each factor,the power consumption curve and agitation characteristic curve were drawn to compare the power consumption and mixing results in the stirred *** of the agitation characteristic curves were compared with the previous published literatures and *** is found that the agitation characteristic curves reflect the tendency of power consumption and particles distribution well in stirred *** good agreement indicates the applicability of the agitation characteristic curves for the study of light particles distribution in stirred tank.

关键词： Agitation characteristic curve Geometrical and physical factors Light particles Solid–liquid mixing Stirred tank

QSAR study on the non-monotonic dose-response curve of PCBs in chicken embryo hepatocyte bioassay

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Science China Chemistry 2009年第5期52卷 662-669页

作者： YunSong Mu AiQian Zhang ChangAn Gao SuFen Peng LianSheng Wang State Key Laboratory of Pollution Control and Resource Reuse School of Environment Nanjing University Nanjing 210093 China

Endocrine disrupting chemicals (EDCs) in the natural environment exhibit a unique non-monotonic dose-response curve and it is impossible to select one simple index to characterize the bilogogical activity of these compounds. Quantitative structure-activity relationship (QSAR) study on non-monotonic dose-response curve has become a real challenge presently. In order to explore the possible mechanism for the non-monotonic dose-response curve of polychlorinated biphenyls congeners (PCBs) in chicken embryo hepatocyte bioassay, AM1 method of ChemOffice was adopted to calculate necessary structure descriptors for PCBs, while the interactions between PCBs and simulated AhR ligand binding domain (LBD) were analyzed by using FlexX in SYBYL7.0. Different binding modes for PCBs have been distinguished not only from aligned conformation but also from free binding energy. Some QSAR models were established separately for both low and high doses ranges, revealing that receptor binding may predominate in the interference of the physiological function of cytochrome P4501A-P4501A in the low doses range. But with the higher doses range, the EROD suppression might be related to acute toxicity owing to molecular polarity or distribution of charges and consequently damage structure and function of chicken embryo hepatocyte.

关键词： polychlorinated biphenyls congeners (PCBs) non-monotonic dose-response curve quantitative structure-activity relationship (QSAR)

ON SOME SIMPLE METHODS TO DERIVE THE HAIRCLIP AND PAPERCLIP SOLUTIONS OF THE curve SHORTENING FLOW

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Acta Mathematica Scientia 2019年第6期39卷 1674-1694页

作者： Dong-Ho TSAI Xiaoliu WANG Department of Mathematics National Tsing Hua UniversityHsinchu 30013China Department of Mathematics Southeast UniversityNanjing 210096China

We use two simple methods to derive four important explicit graphical solutions of the curve shortening flow in the plane. They are well-known as the circle, hairclip, paperclip, and grim reaper solutions of the curve shortening flow. By the methods, one can also see that the hairclip and the paperclip solutions both converge to the grim reaper solutions as t → -∞.

关键词： curve shortening flow grim reaper solution hairclip solution paperclip solution

A unified approach to kinematic synthesis of mechanism by adaptive curve fitting

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Science China(Technological Sciences) 2004年第1期47卷 85-96页

作者： WANG Delun WANG Shufen School of Mechanical Engineering Dalian University of Technology Dalian 116024 China School of Mechanical Engineering Dalian University of Technology Dalian 116024 China

A unified approach to kinematic synthesis of mechanism is presented in this paper. Firstly a new approach to adaptive curve fitting is presented, which leads the normal fitting error to be minimum for a series of given discrete points, including a plane curve fitting, a spherical curve fitting and a ruled surface fitting in terms of invariants of ruled surface. Approximate characteristic points and lines are defined, such as an approximate circle point, an approximate slide point, an approximate spherical cone point and an approximate constant axis with an approximate spherical image cone point and an approximate striction curve. Then,the ruled surface fitting will be converted into a space curve fitting and a spherical curve fitting by differential geometry. Based on these definitions and the adaptive curve fitting approaches, the unified mathematical model is set up for the kinematic synthesis of mechanism from planar, spherical to spatial motion. Finally, a planar mechanism or a spatial mechanism can be synthesized by means of searching for two approximate characteristic points, or a characteristic point and a characteristic line, even two characteristic lines. This puper lays a theoretic base for the existence of the best solution and the convergence of the optimum algorithm.

关键词： kinematics, mechanism synthesis, ruled surface, adaptive curve fitting.

Carrying capacity for the electromagnetic suspension low-speed maglev train on the horizontal curve

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Science China(Technological Sciences) 2010年第4期53卷 1082-1087页

作者： CUI Peng,LI Jie & LIU DeSheng Maglev Engineering Center,National University of Defense Technology,Changsha 410073,China 1. Maglev Engineering Center National University of Defense Technology Changsha 410073 China

Aiming at the lateral dislocation between the electromagnets and the rails on a horizontal curve,we investigated a single magnetic bogie of the maglev train in this *** magnetic levitation and guidance forces supplied by the suspension modules were deduced by the flux tube *** to the dynamic equilibrium equations of the maglev train on the curved track with cant,several major factors that influence the carrying capacity were analyzed,and the formula of the carrying capacity was *** results provide a theoretical reference for the design of maglev train.

关键词： low-speed maglev train curve flux tube carrying capacity

Characteristics of soil water retention curve at macro-scale

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Science China(Technological Sciences) 2009年第10期52卷 2990-2996页

作者： TIAN FuQiang MOU LiQin HU HePing State Key Laboratory of Hydro-Science and Engineering Department of Hydraulic EngineeringTsinghua UniversityBeijing 100084China

Scale adaptable hydrological models have attracted more and more attentions in the hydrological modeling research community, and the constitutive relationship at the macro-scale is one of the most important issues, upon which there are not enough research activities yet. Taking the constitutive relationships of soil water movement--soil water retention curve (SWRC) as an example, this study extends the definition of SWRC at the micro-scale to that at the macro-scale, and aided by Monte Carlo method we demonstrate that soil property and the spatial distribution of soil moisture will affect the features of SWRC greatly. Furthermore, we assume that the spatial distribution of soil moisture is the result of self-organization of climate, soil, ground water and soil water movement under the specific boundary conditions, and we also carry out numerical experiments of soil water movement at the vertical direction in order to explore the relationship between SWRC at the macro-scale and the combinations of climate, soil, and groundwater. The results show that SWRCs at the macro-scale and micro-scale presents totally different features, e.g., the essential hysteresis phenomenon which is exaggerated with increasing aridity index and rising groundwater table. Soil property plays an important role in the shape of SWRC which will even lead to a rectangular shape under drier conditions, and power function form of SWRC widely adopted in hydrological model might be revised for most situations at the macro-scale.

关键词： scale issue constitutive relationship soil water retention curve Richards equation

Determination of site-specific soil-water characteristic curve from a limited number of test data-A Bayesian perspective

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Geoscience Frontiers 2018年第6期9卷 1665-1677页

作者： Lin Wang Zi-Jun Cao Dian-Qing Li Kok-Kwang Phoon Siu-Kui Au State Key Laboratory of Water Resources and Hydropower Engineering Science Key Laboratory of Rock Mechanics in Hydraulic Structural Engineering(Ministry of Education)Wuhan University8 Donghu South RoadWuhan 430072China Department of Civil and Environmental Engineering National University of SingaporeBlk E1A#07-031 Engineering Drive 2Singapore 117576Singapore Institute for Risk and Uncertainty University of LiverpoolHarrison Hughes BuildingBrownlow HillLiverpoolL69 3GHUnited Kingdom

Determining soilewater characteristic curve(SWCC) at a site is an essential step for implementing unsaturated soil mechanics in geotechnical engineering practice, which can be measured directly through various in-situ and/or laboratory tests. Such direct measurements are, however, costly and timeconsuming due to high standards for equipment and procedural control and limits in testing apparatus. As a result, only a limited number of data points(e.g., volumetric water content vs. matric suction)on SWCC at some values of matric suction are obtained in practice. How to use a limited number of data points to estimate the site-specific SWCC and to quantify the uncertainty(or degrees-of-belief) in the estimated SWCC remains a challenging task. This paper proposes a Bayesian approach to determine a site-specific SWCC based on a limited number of test data and prior knowledge(e.g., engineering experience and judgment). The proposed Bayesian approach quantifies the degrees-of-belief on the estimated SWCC according to site-specific test data and prior knowledge, and simultaneously selects a suitable SWCC model from a number of candidates based on the probability logic. To address computational issues involved in Bayesian analyses, Markov Chain Monte Carlo Simulation(MCMCS), specifically Metropolis-Hastings(M-H) algorithm, is used to solve the posterior distribution of SWCC model parameters, and Gaussian copula is applied to evaluating model evidence based on MCMCS samples for selecting the most probable SWCC model from a pool of candidates. This removes one key limitation of the M-H algorithm, making it feasible in Bayesian model selection problems. The proposed approach is illustrated using real data in Unsaturated Soil Database(UNSODA) developed by U.S. Department of Agriculture. It is shown that the proposed approach properly estimates the SWCC based on a limited number of site-specific test data and prior knowledge, and reflects the degrees-of-belief on the estimated SWCC

关键词： Soilewater characteristic curve Bayesian approach Unsaturated soils Degrees-of-belief UNSODA

Convergence of Solutions of General Dispersive Equations Along curve

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Chinese Annals of Mathematics,Series B 2019年第3期40卷 363-388页

作者： Yong DING Yaoming NIU School of Mathematical Sciences Beijing Normal UniversityLaboratory of Mathematics and Complex Systems (BNU) Ministry of Education Faculty of Mathematics Baotou Teachers' College

In this paper, the authors give the local L^2 estimate of the maximal operator S_(φ,γ)~* of the operator family {S_(t,φ,γ)} defined initially by ■which is the solution(when n = 1) of the following dispersive equations(~*) along a curve γ:■where φ : R^+→R satisfies some suitable conditions and φ((-?)^(1/2)) is a pseudo-differential operator with symbol φ(|ξ|). As a consequence of the above result, the authors give the pointwise convergence of the solution(when n = 1) of the equation(~*) along curve γ.Moreover, a global L^2 estimate of the maximal operator S_(φ,γ)~* is also given in this paper.

关键词： L^2 estimate Global maximal operator Dispersive equation curve

Modelling surface runoff using the soil conservation service-curve number method in a drought prone agro-ecological zone in Rwanda

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International Soil and Water Conservation Research 2019年第1期7卷 9-17页

作者： Dieudonne Uwizeyimana Stephen M.Mureithi Simon M.Mvuyekure George Karuku Geoffrey Kironchi Department of Land Resource Management and Agricultural Technology University of NairobiP.O Box 2905300625 NairobiKenya Ministry of Agriculture and Animal Resources of Rwanda P.O.Box 6961KigaliRwanda Rwanda Agriculture and Animal Resources Development Board P.O.Box 5016KigaliRwanda

Runoff farming is reported to improve land productivity and crop yields in hot and dry *** study was conducted to assess the available rainwater that can be harvested in a conserved catchment in a drought prone agro-ecological *** study was carried out in the Cyili sub-catchment,southern province of Rwanda,which has an irregular rainfall pattern and unexploited runoff *** Conservation Service-curve Number method (SCS-CN),CROPWAT model version 8 and Hazen model with an average daily rainfall data recorded from 1971 to 2016 were applied to estimate the runoff and water requirements in the study *** of the study revealed that more than half rainfall water received in the catchment was lost through runoff (229.8 mm) and effective rainfall was lower (246.9 mm) than the actual crop water requirement for maize (330 mm).The expected seasonal surface runoff volume to be harvested by the farmers was 3008 m3 ha-1 per season and 1.29 × 106 m3 per season for the entire whole sub-catchment (430 ha).Based on Hazen model,the return period of low rainfall (dry spell) event would be expected every 2 years with a 98% probability of *** sub-catchment has higher potential runoff volume to stabilize the deficit of water demand in the period of short rainy *** suggests that rainwater harvesting through supplementary irrigation is an option to improve the crop yield in the dry period as well as in the annual dry season.

关键词： Available rainwater Cyili sub-Catchment curve number Runoff Rwanda