检索结果-南通市图书馆

Porosity of bimodal sediment mixture with particle filling

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

International Journal of Sediment Research 2017年第2期32卷 253-259页

作者： weiming wu Wei Li Department of Civil and Environmental Engineering Clarkson University Institute of Coastal and Nearshore Engineering Ocean CollegeZhejiang University

The porosity of a bimodal sediment mixture is affected by the filling of fine particles in the voids of coarse particles when the particle size range is *** classical ideal packing models tend to overestimate the filling,and,thus,underestimate the porosity of the *** this study,an existing random filling model is improved by considering a three-dimensional packing configuration,and a new model is developed by considering how many fine particles are required and how many are available to cover the surface of coarse particles in the sediment *** developed models are validated using measured data and compared with existing *** new model can reproduce well the variation trend of the mixture porosity as the fraction of fine particles varies.

关键词： Bimodal sediment mixture Porosity Particle filling Particle packing

Rapid dynamical pattern recognition for sampling sequences

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Science China(Information Sciences) 2021年第3期64卷 118-135页

作者： weiming wu Qian WANG Chengzhi YUAN Cong WANG School of Automation Science and Engineering South China University of Technology School of Control Science and Engineering Shandong University Department of Mechanical Industrial and Systems Engineering University of Rhode Island

In this paper, based on deterministic learning, we propose a method for rapid recognition of dynamical patterns consisting of sampling sequences. First, for the sequences yielded by sampling a periodic or recurrent trajectory(a dynamical pattern) generated from a nonlinear dynamical system, a sampled-data deterministic learning algorithm is employed for modeling/identification of inherent system dynamics. Second,a definition is formulated to characterize similarities between sampling sequences(dynamical patterns) based on differences in the system dynamics. Third, by constructing a set of discrete-time dynamical estimators based on the learned knowledge, similarities between the test and training patterns are measured by using the average L1 norms of synchronization errors, and general conditions for accurate and rapid recognition of dynamical patterns are given in a sampled-data framework. Finally, numerical examples are discussed to illustrate the effectiveness of the proposed method. We demonstrate that not only a test pattern can be rapidly recognized corresponding to a similar training pattern, but also the proposed recognition conditions can be verified step by step based on historical sampling data. This makes a distinction compared with the previous work on rapid dynamical pattern recognition for continuous-time nonlinear systems, in which the recognition conditions are difficult to be verified by using continuous-time signals.

关键词： deterministic learning dynamical pattern recognition sampling sequence synchronization

Dynamical pattern recognition for univariate time series and its application to an axial compressor

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Control Theory and Technology 2024年第1期22卷 39-55页

作者： Jingtao Hu weiming wu Zejian Zhu Cong Wang Center for Intelligent Medical Engineering School of Control Science and TechnologyShandong UniversityJinan250061ShandongChina School of Automation Science and Engineering South China University of TechnologyGuangzhou510641GuangdongChina

In this paper, a learning and recognition approach is proposed for univariate time series composed of output measurements of general nonlinear dynamical systems. Firstly, a class of dynamical systems in the canonical form is derived to describe the univariate time series by introducing coordinate transformation. An observer-based deterministic learning technique is then adopted to achieve dynamical modeling of the associated transformed systems of the training univariate time series, and the modeling results in the form of radial basis function network (RBFN) models are stored in a pattern library. Subsequently, multiple observer-based dynamical estimators containing the RBFN models in the pattern library are constructed for a test univariate time series, and a recognition decision scheme is proposed by the derived recognition indicator. On this basis, more concise recognition conditions are provided, which is beneficial for verifying the recognition results. Finally, simulation studies on the Rossler system and aero-engine stall warning verify the effectiveness of the proposed approach.

关键词： Dynamical pattern recognition Deterministic learning Stall warning Radial basis function network Sampled-data observer

Porosity of bimodal and trimodal sediment mixtures

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

International Journal of Sediment Research 2022年第2期37卷 258-271页

作者： Chamil Perera weiming wu Ian Knack Department of Civil and Environmental Engineering Clarkson University

This study focuses on the prediction of the porosity of nonuniform sediment mixtures,considering the effects of particle packing.A random particle packing model has been developed for the porosity of bimodal mixtures by extending the existing random particle filling *** in the developed model are calibrated by fitting the model to measured data for a variety of bimodal mixtures,including spherical glass particles,rounded quarry grains,and natural *** model coefficients are found to be functions of the diameter ratio of coarse and fine particles,separately for spherical glass particles and natural sediments due to differences in particle *** bimodal mixture model is then extended to trimodal particle mixtures in three approaches:two based on serial packing and one based on random *** models are tested against experimental data of six trimodal mixtures with spherical glass *** results show that the random packing model and the fine-medium-coarse particle serial packing model predict well the observed trimodal mixture porosities.

关键词： Porosity Particle filling Particle packing Bimodal mixture Trimodal mixture

Numerical simulation of solitary and random wave propagation through vegetation based on VOF method

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Acta Oceanologica Sinica 2013年第7期32卷 38-46页

作者： ZHANG Mingliang HAO Zining ZHANG Yunpeng wu weiming School of Ocean and Environment Engineering Dalian Ocean University National Center for Computational Hydroscience and Engineering University of MississippiUniversity

A vertical two-dimensional numerical model has been applied to solving the Reynolds Averaged Navier- Stokes （RANS} equations in the simulation of current and wave propagation through vegetated and non- vegetated waters. The k-e model is used for turbulence closure of RANS equations. The effect of vegeta- tion is simulated by adding the drag force of vegetation in the flow momentum equations and turbulence model. To solve the modified N-S equations, the finite difference method is used with the staggered grid system to solver equations. The Youngs＇ fractional volume of fluid （VOF） is applied tracking the free sur- face with second-order accuracy. The model has been tested by simulating dam break wave, pure current with vegetation, solitary wave runup on vegetated and non-vegetated channel, regular and random waves over a vegetated field. The model reasonably well reproduces these experimental observations, the model- ing approach presented herein should be useful in simulating nearshore processes in coastal domains with vegetation effects.

关键词： VOF method vegetation solitary regular and random waves wave height attenuation k-emodel

维普期刊数据库

Coupling of wave and current numerical model with unstructured quadtree grid for nearshore coastal waters

在线全文

学校读者我要写书评

暂无评论

Science China(Technological Sciences) 2012年第2期55卷 568-580页

作者： ZHANG MingLiang wu weiming LIN LiHua YU JiangNan School of Ocean Technology and Environment Dalian Ocean UniversityDalian 116023China National Center for Computational Hydroscience and Engineering The University of MississippiUniversity 38677MSUSA US Army Engineer Research and Development Center 39180MSUSA

This paper presents 2D wave-current interaction model for evaluating nearly horizontal wave-induced currents in the surf-zone and coastal *** hydrodynamic model is the two-dimensional depth-averaged nonlinear shallow water equations by using an unstructured non-staggered and multiple-level quadtree rectangular mesh,this mesh information is stored in simple data structures and it is easy to obtain a locally high resolution for important *** intercell fluxes are computed based on the HLL(Harten-Lax-van Leer) approximate Riemann solver with shock capturing capability for computing the dry-to-wet interface of coastal *** effects of pressure and gravity are included in source term in the model,this treatment can simplify the computation and eliminate numerical imbalance between source and flux *** wave model readily provides the radiation stresses that represent the shortwave-averaged forces in a water column for the hydrodynamic model and the wave model takes into account the effect of wave-induced nearshore currents and water *** coupling model is applied to verify different experimental cases and real life case of considering the wave-current *** calculated results agree with analytical solution,experimental and field *** results show that the modeling approach presented herein should be useful in simulating the nearshore processes in complicated natural coastal domains.

关键词： wave-current interaction unstructured quadtree grid finite volume method HLL approximate Riemann solver waveaction spectral model

维普期刊数据库

Synergic catalysis of W and Ni originating from substitution of trivacant phosphotungstate for the selective oxidation of aniline to azoxybenzene

在线全文

学校读者我要写书评

暂无评论

Chinese Chemical Letters 2024年第2期35卷 558-563页

作者： Sheng Cai Xiao-Yuan wu weiming wu Sa-Sa Wang Can-Zhong Lu CAS Key Laboratory of Design and Assembly of Functional Nanostructures and Fujian Provincial Key Laboratory of NanomaterialsFujian Institute of Research on the Structure of MatterChinese Academy of SciencesFuzhou 350002China College of Chemistry and Materials Science Fujian Normal UniversityFuzhou 350117China Xiamen Institute of Rare Earth Materials Chinese Academy of SciencesXiamen 361021China University of Chinese Academy of Sciences Beijing 100049China

Partial substitution of polyoxometalate(POM)is an efficient route to modulate the catalytic property of maternal *** this work,a new Keggin type POM involving{Ni 6}cluster,{[Ni(H_(2)O)_(2)(Dach)_(2)][Ni(Dach)_(2)]_(2)}{[Ni_(6)Cl(μ-OH)_(3)(H_(2)O)(Dach)_(3)(WO_(4))(PW9 O_(3)_(4))][Ni_(6)(μ-OH)_(3)(H_(2)O)_(2)(Dach)_(3)(WO_(4))(PW9 O_(3)_(4))]}Cl·27H_(2)O,(1,Dach=1,2-diaminocyclohexane)was *** 1 shows excellent catalytic performance in the selective oxidation of aniline to azoxybenzene(AOB)in *** apparently different results from that with the matrix{PW_(9)O_(34)}({PW9})suggest the successful regulation of the catalytic property of{PW9}by the introduction of the{Ni6}cluster into the *** experimental results indicate that the highlighted performance of 1 is contributed by the synergy of W and Ni sites,which are respectively responsible for the oxidation and condensation steps in the production of *** good selectivity to AOB is essentially attributed to the effective modulation of the reaction rates of oxidation and condensation steps by W and Ni sites,respectively.

关键词： Polyoxometalate {Ni_(6)}cluster Modulated catalytic property Aniline oxidation Azoxybenzene

维普期刊数据库

Erosion rate of sand and mud mixtures

在线全文

学校读者我要写书评

暂无评论

International Journal of Sediment Research 2020年第6期35卷 563-575页

作者： Chamil Perera Jarrell Smith weiming wu David Perkey Anthony Priestas Department of Civil and Environmental Engineering Clarkson University Coastal and Hydraulics Laboratory US Army Corps of Engineers

Erosion of mixed cohesive and noncohesive sediments is studied using the erosion test instrument *** sediment mixtures are composed of well-sorted quartz sand(0.25-0.5 mm) and one of the three used muds:kaolinite,kaolinite-bentonite and Mississippi River *** mud contents cover from 0 to 100%.The measured data of erosion rate and bed shear stress are used to examine the segmented linear,nonlinear,and exponential erosion *** parameters of each erosion model are related to the physical properties of sediment mixtures,including clay fraction,mud fraction,mixture dry density,and mud dry *** is found that the three models can fit well with the data,and their parameters have strong relations with the mud fraction and mud dry density,to a less extent with the clay fraction,but not with the mixture dry density.

关键词： Cohesive sediments Noncohesive sediments Sand and mud mixtures Segmented linear model Nonlinear model Exponential model

Absolute Cross Sections for Single Ionization of Ar^(+) and Cl^(+) by Electron Impact

在线全文

同方期刊数据库

学校读者我要写书评

暂无评论

Chinese Physics Letters 1994年第2期11卷 73-75页

作者： SHI Wei FANG Dufei LU Fuquan GAO Haibin GU Jian wu Songmao wu weiming TANG Jiayong YANG Fujia T.D.Lee Physics Laboratory and Department of Nuclear Science Fudan UniversityShanghai 200433

A crossed-beam facility for electron impact ionization of ions was *** absolute cross sections for single ionization of Ar^(+) and Cl^(+) ions at electron energies ranging from 30 to 500eV were *** uncertainty is abou... 详细信息

关键词： absolute Electron ionization