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Experimental study on three dimensional movements of particles Ⅱ Effects of particle diameter on turbulence characteristics

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International Journal of Sediment Research 2009年第2期24卷 169-176页

作者： Limo TANG1 and Xingkui WANG2 1State Key Laboratory of Hydrology-Water Resources and Hydraulic Engineering,hohai university, Nanjing 210098,China 2 Prof.,State Key Laboratory of Hydroscience and Engineering,Tsinghua university,Beijing 100084,China State Key Laboratory of Hydrology-Water Resources and Hydraulic Engineering Hohai University Nanjing 210098 China State Key Laboratory of Hydroscience and Engineering Tsinghua University Beijing 100084 China

Based on the 3D PTV(Particle Tracking Velocimetry) measuring system,the 3D movement characteristics of particles with four different diameters were investigated. Under specific flow conditions,the impact of particle diameters on 3D motion of particles was studied,and the turbulence characteristics were analyzed by different statistical methods. The results showed that the turbulence intensity of coarse particle decreased as the diameter increased. In near wall region,the probability density distributions of longitudinal and vertical fluctuation velocities both deviated from the normal distribution;while in the outer region,the probability density distribution of vertical fluctuation velocity approximately agreed with the normal distribution.

关键词： Particle diameter Turbulence Probability density distribution

Transfer function based equivalent modeling method for wind farm

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Journal of Modern Power Systems and Clean Energy 2019年第3期7卷 549-557页

作者： Feng WU Junxia QIAN Ping JU Xiaoping ZHANG Yuqing JIN Dan XU Michael STERLING College of Energy and Electrical Engineering Hohai UniversityNanjing 210098China Department of Electronic Electrical and Computer EngineeringUniversity of BirminghamBirminghamB152TTUK

To effectively study the dynamics of power systems with large-scale wind farms(WFs), an equivalent model needs to be developed. It is well known that back-toback converters and their controllers are important for the dynamic responses of the wind turbine(WT) under disturbances. However, the detailed structure and parameters of the back-to-back converters and their controllers are usually unknown to power grid operators. Hence, it is difficult to build an accurate equivalent model for the WF using the component model-based equivalent modeling method. In this paper, a transfer function based equivalent modeling method for the WF is proposed. During modeling, the detailed structure and parameters of the WF are not required. The objective of the method is reproducing the output dynamics of the WF under the variation of the wind speed and power grid faults. A decoupled parameter-estimation strategy is also developed to estimate the parameters of the equivalent model. A WF that consists of 16 WTs is used to test the proposed equivalent model. Additionally,the proposed equivalent modeling method is applied to build the equivalent model for a real WF in Northwest China. The effectiveness of the proposed method is validated by the real measurement data.

关键词： Wind farm Equivalent modeling Transfer function Parameter estimation Particle swarm optimization

Compression behavior of metal foams with real pore structures through CT scan images

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Journal of Iron and Steel Research International 2022年第11期29卷 1886-1897页

作者： Lei Wang Kai Jiang Dong-hui Yang College of Mechanics and Materials Hohai UniversityNanjing 211100JiangsuChina Suqian Research Institute of hohai university Suqian 223814JiangsuChina

Based on the real pore structure obtained from computed tomography(CT)scan images,a three-dimensional(3D)model of the metal foam sample with specified porosity is established,and the model is compressed and simulated by finite element method with the simulation results compared with the experimental test results for *** the same time,based on the spatial distribution characteristics of cells extracted from 3D model construction,a widely used metal foam model with Voronoi pore structure or spherical pore structure was established and simulated under *** two compression simulation results with regular pore structure models were also compared with the experimental results and CT model results to study the influence of cell wall morphology on the compression performance of metal *** simulation results show that CT model agrees well with the experimental results and is more accurate than Voronoi pore or spherical pore model,which can provide a more reasonable option for investigation of metal foams.

关键词： Metal foam Computed tomography scan Three-dimensional reconstruction Cell wall morphology Compression performance

Inhibitory effects of the extracts with different solvents from three compositae plants on cyanobacterium Microcystis aeruginosas

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science China Chemistry 2011年第7期54卷 1123-1129页

作者： NI LiXiao HAO XiangYang LI ShiYin CHEN ShiJin REN GaoXiang ZHU Liang Key Laboratory of Integrated Regulation and Resource Development on Shallow Lakes Ministry of Education College of Environmental science and Engineering Hohai University Nanjing 210098 China Department of Environmental science and Engineering School of Geography Science Nanjing Normal University Nanjing 210097 China

The algicidal activity of the terrestrial plants is a novel and promising means for alga control of eutrophic waters. In this study, three compositae plants-Artemisia annua （A. annua）, Conyza canadensis （ C. canadensis）, and Erigeron annuus （E. annuus） were selected and antialgal activity of petroleum ether （PE）, ethyl acetate （EA） and ethanol extracts of these plants on blue algae Microcystis aeruginosa was investigated. The result shows the EA extracts of these plants present the stronger inhibitory effects. The results of the further separation of PE and EA extracts according to water-solubility and acidity or alkalinity show that fatty acids and telpenoids in A. annua, terpenoids and organic acid in C. Canadensis and E. Annuus may be the main antialgal active constituents. This study suggested that the EA extracts of these plants could become the potential algicide to prevent water blooming.

关键词： compositae plants fractional extraction microcystis aeruginosa antialgal activity

Nutrient exchange and release experiment and its simulation study in lake water-sediment interface

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Journal of Environmental sciences 2006年第3期18卷 591-595页

作者： XUE Lian-qing HAO Zhen-chun State Key Laboratory of Hydrology-Water Resources and Hydraulic Engineering College of Water Resources and Environment Hohai UniversityNanjing 210098 China

The sediment distributed and insolated under lake was collected for experiments. The nutrient layer distribution conditions of sampled sediment and its physical and chemical characteristics were analyzed to simulate and assess the influence degree to lake water quality. Based on the dynamic water exchanging experiments the nutrient release process in sediment and influence mechanism to substance exchanging on water-sediment interface was studied, and the correlation between the changing content of total phosphors and total nitrogen in sediment and covered water were analyzed for setting up a simulation model. At the same time the influence degree is explained in detail. The experimental results indicated that even if clean water without nutrient contents was used for water exchangement so as to decrease pollution or prevent eutrophication, however owing to the vertical nutrient distribution in lake sediment, it will lead to the increasing release amount greatly especially when the organic nutrient contained in sediment turns into inorganic status because of isolation. Besides the release process of total phosphate （TP） and total nitrogen （TN） were modeled and each nutrient＇s exchanging equation at interface caused by covered water nutrient concentration changing was set up. According to the simulating prediction, TP and TN content of cover water will also sustain a steady higher level in a long period. The nutrient release amount of sediment is not only affected by the covered water concentration but also connects with accumulative time. The experiments provide the fundamental theoretical and practical basis for taking ecological restoration project. And research is helpful to prevent or restore lake eutrophication.

关键词： phosphate and nitrogen release water-sediment interface experiments simulation model

A NEGATIVE ANSWER TO A PROBLEM OF FREMLIN AND MENDOZA

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Acta Mathematica Scientia 2007年第4期27卷 813-820页

作者：叶国菊 Stefan Schwabik College of science hohai university Nanjing210098China Mater naticky ústav AV R itná 25 115 67 Praha 1Czech Republic

This article studies some convergence results for the McShane integral of functions mapping the interval [0, 1] into a Banach space X from the point of view of an open problem proposed by *** and J. Mendoza in [2], al... 详细信息

关键词： Abstract function Pettis integral McShane integral

Effect of Fly Ash on TSA Resistance of Cement-based Material

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Journal of Wuhan university of Technology(Materials science) 2011年第3期26卷 561-566页

作者：张风臣 College of Mechanics and Materials Hohai University

Thaumasite form of sulfate attack（TSA）is a major concern in evaluating durability of concrete structures subjected to sulfate and carbonate *** means of Fourier transform infrared spectroscopy （FT-IR）,X-ray diffraction（XRD）,scanning electron microscopy（SEM）,and energy dispersive spectrum（EDS） as well as Raman spectra of erosion substances,effect of fly ash on TSA resistance of Portland cement-based material were *** in magnesium sulfate solution with 33 800 ppm mass concentration of SO 4 2-at 5±2℃for 15 weeks,ratio of compressive strength loss decreased as binder replacement ratio of fly ash ***,when binder replacement of fly ash was 60%,compressive strength *** thaumasite came into being in samples with 0,15%binder replacement ratio of fly ash,ettringite and gypsum appeared in those with 30%,45%,60%binder replacement ratio of fly *** mentioned above showed that fly ash can restrain formation of thaumasite and improve TSA resistance of Portland cement-based material sufficiently.

关键词： fly ash cement-based material thaumasite

Improved acetone sensing properties of flat sensors based on Co-SnO_(2) composite nanofibers

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Chinese science Bulletin 2011年第24期56卷 2644-2648页

作者： HU Lei LI Yi College of Environmental Hohai UniversityNanjing 210098China Key Laboratory of Integrated Regulation and Resource Development on Shallow Lakes of Ministry of Education Hohai UniversityNanjing 210098China

Co-SnO_(2) composite nanofibers were synthesized by an electrospinning method and characterized by X-ray diffraction, field emission scanning electron microscopy, and transmission electron microscopy. Gas sensors were fabricated by spinning these nanofibers onto flat ceramic substrates, which had signal electrodes and heaters on their top and bottom surfaces, respectively. Compared with sensors loaded with pure SnO_(2) nanofibers, the Co-SnO_(2) nanofiber sensors exhibited improved acetone sensing properties with high selectivity and rapid response and recovery times. The response was 33 when the sensors were exposed to 100 μL/L acetone at 330°C, and the corresponding response with 100 μL/L of ethanol was only 6. The response and recovery times to acetone were about 5 and 8 s, respectively. These results indicate Co-SnO_(2) composite nanofibers are good candidates for fabrication of high performance acetone sensors for practical application.

关键词：气体传感器纳米复合纤维 SnO2 丙酮场发射扫描电子显微镜复合纳米纤维菲亚特透射电子显微镜

CONSTRUCTION OF CUBATURE FORMULAS VIA BIVARIATE QUADRATIC SPLINE SPACES OVER NON-UNIFORM TYPE-2 TRIANGULATION

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Journal of Computational Mathematics 2022年第2期40卷 205-230页

作者： Jiang Qian Xiquan Shi Jinming Wu Dianxuan Gong College of science Hohai UniversityNanjing 211100China Key Laboratory of Coastal Disaster and Defence(hohai university) Ministry of EducationNanjing 210098China Division of Physics EngineeringMathematicsand Computer ScienceDelaware State UniversityDoverDE 19901USA Statistics and Mathematics Institute Zhejiang Gongshang UniversityHangzhou 310018China College of science North China University of Science and TechnologyTangshan 063210China

In this paper,matrix representations of the best spline quasi-interpolating operator over triangular sub-domains in S_(2)^(1)(△_(mn)^(2),and coefficients of splines in terms of B-net are calculated ***,by means of coefficients in terms of B-net,computation of bivariate numerical cubature over triangular sub-domains with respect to variables x and y is transferred into summation of coefficients of splines in terms of *** concise bivariate cubature formulas are constructed over rectangular ***,by means of module of continuity and max-norms,error estimates for cubature formulas are derived over both sub-domains and the domain.

关键词： Multivariate spline Bivariate cubature Conformality of Smoothing Cofactor Method B-net Non-uniform Type-2 Triangulation