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Damage and progressive failure of concrete structures using non-local peridynamic modeling

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Science China(Technological Sciences) 2011年第3期54卷 591-596页

作者： HUANG Dan1,2, ZHANG Qing1,2 & QIAO PiZhong1,3 1 State Key Laboratory of Hydrology-Water Resources and Hydraulic Engineering, hohai university, Nanjing 210098, China 2 Department of Engineering Mechanics, hohai university, Nanjing 210098, China 3 Department of Civil and Environmental Engineering, Washington State university, Pullman, WA 99164-2910, USA State Key Laboratory of Hydrology-Water Resources and Hydraulic Engineering Hohai University Nanjing China Department of Engineering Mechanics Hohai University Nanjing China Department of Civil and Environmental Engineering Washington State University Pullman USA

Peridynamics (PD), a recently developed theory of solid mechanics, which employs a non-local model of force interaction and makes use of integral formulation rather than the spatial partial differential equations used in the classical continuum mechanics theory, has shown effectiveness and promise in solving discontinuous problems at both macro and micro scales. In this paper, the peridynamics theory is used to analyze damage and progressive failure of concrete structures. A non-local peridynamic model for a rectangular concrete plate is developed, and a central pairwise force function is introduced to describe the interior interactions between particles within some definite distance. Damage initiation, evolution and crack propagation in the concrete model subject to in-plane uni-axial tension, in-plane uni-axial compression and out-of-plane impact load are investigated respectively. The numerical results show that discontinuities appear and grow spontaneously as part of the solution to the peridynamic equations of motion, and no special failure criteria or re-meshing techniques are required, which proves the potential of peridynamic modeling as a promising technique for analyzing the progressive failure of concrete materials and structures.

关键词：混凝土结构破坏过程损伤非局部模型偏微分方程理论建模技术分析混凝土材料

Multivariate analysis in dam monitoring data with PCA

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Science China(Technological Sciences) 2010年第4期53卷 1088-1097页

作者： YU Hong1,2,WU ZhongRu1,2,BAO TengFei1,2 & ZHANG Lan1,2 1 State Key Laboratory of Hydrology-Water Resources and Hydraulic Engineering,hohai university,Nanjing 210098,China 2 National Engineering Research Center of Water Resources Efficient Utilization and Engineering Safety,hohai university,Nanjing 210098,China State Key Laboratory of Hydrology-Water Resources and Hydraulic Engineering Hohai University Nanjing China National Engineering Research Center of Water Resources Efficient Utilization and Engineering Safety Hohai University Nanjing China

Given the limitation of traditional univariate analysis method in processing the multicollinearity of dam monitoring data,this paper reconstructs the multivariate response variables by introducing principal component analysis(PCA) method,explores the ways of determining principal components(PCs),and extracts a few PCs that have major influence on data variance.For steady observation series,a control field for the whole observation values has been established based upon PCA;for unsteady observation series that have significant tendency,a control field for the future observation values has been constructed according to PC statistical predication model.These methods have already been applied to an actual project and the results showed that data interpretation method with PCA can not only realize data reduction,lower data redundancy,and reduce noise and false alarm rate,but also be effective to data analysis,having a broad application prospect.

关键词： dam safety monitoring multivariate response variables principal component analysis data reduction

Certificateless Strong Key-Insulated Signature Without Random Oracles

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Journal of Shanghai Jiaotong university(Science) 2011年第5期16卷 571-576页

作者：万中美孟祥芹洪璇 College of Science Hohai University Department of Computer Science Shanghai Normal University

It is important to ensure the private key secure in cryptosystem. To reduce the underlying danger caused by the private key leakage, Dodis et al. (2003) introduced the notion of key-insulated security. To handle the private key leakage problems in certificateless signature schemes, we propose a new certificateless strong key-insulated signature scheme. Our scheme has two desirable properties. First, its security can be proved without utilizing the random oracle model. Second, it solves the key escrow problems in identity-based key-insulated signatures (IBKISs).

关键词： key-insulated key leakage certificateless bilinear pairings

Reliable calculations of nuclear binding energies by the Gaussian process of machine learning

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Nuclear Science and Techniques 2024年第6期35卷 130-144页

作者： Zi-Yi Yuan Dong Bai Zhen Wang Zhong-Zhou Ren School of Physics Science and Engineering Tongji UniversityShanghai 200092China College of Science Hohai UniversityNanjing 211100China Key Laboratory of Advanced Micro-Structure Materials Ministry of EducationShanghai 200092China

Reliable calculations of nuclear binding energies are crucial for advancing the research of nuclear physics.Machine learning provides an innovative approach to exploring complex physical problems.In this study,the nuclear binding energies are modeled directly using a machine-learning method called the Gaussian process.First,the binding energies for 2238 nuclei with Z>20 and N>20 are calculated using the Gaussian process in a physically motivated feature space,yielding an average deviation of 0.046 MeV and a standard deviation of 0.066 MeV.The results show the good learning ability of the Gaussian process in the studies of binding energies.Then,the predictive power of the Gaussian process is studied by calculating the binding energies for 108 nuclei newly included in AME2020.The theoretical results are in good agreement with the experimental data,reflecting the good predictive power of the Gaussian process.Moreover,the-decay energies for 1169 nuclei with 50≤Z≤110 are derived from the theoretical binding energies calculated using the Gaussian process.The average deviation and the standard deviation are,respectively,0.047 MeV and 0.070 MeV.Noticeably,the calculated-decay energies for the two new isotopes 204 Ac(Huang et al.Phys Lett B 834,137484(2022))and 207 Th(Yang et al.Phys Rev C 105,L051302(2022))agree well with the latest experimental data.These results demonstrate that the Gaussian pro-cess is reliable for the calculations of nuclear binding energies.Finally,the-decay properties of some unknown actinide nuclei are predicted using the Gaussian process.The predicted results can be useful guides for future research on binding energies and-decay properties.

关键词： Nuclear binding energies decay Machine learning Gaussian process

Supplementation of alanine improves biomass accumulation and lipid production of Chlorella pyrenoidosa by increasing the respiratory and metabolic processes

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Journal of Oceanology and Limnology 2024年第2期42卷 570-579页

作者： Yongfu LI Tianze ZHAO Wei SUN Ruiwen GAO Guangyuan MA Jiangsu Province Engineering Research Center for Marine Bioresources Sustainable Utilization Key Laboratory of Marine Hazards ForecastingMinistry of Natural ResourcesHohai UniversityNanjing 210098China College of Oceanography Hohai UniversityNanjing 210098China Jiangsu Innovation Center of Marine Bioresources Jiangsu Coast Development Group Co.Ltd.Nanjing 210019China

The function of exogenous alanine(Ala)in regulating biomass accumulation,lipid production,photosynthesis,and respiration in Chlorella pyrenoidosa was studied.Result shows that the supplementation of Ala increased C.pyrenoidosa biomass and lipid production in an 8-d batch culture.The concentration of 10 mmol/L of Ala was optimum and increased the microalgal cell biomass and lipid content by 39.3%and 21.4%,respectively,compared with that in the control(0-mmol/L Ala).Ala supplementation reduced photosynthetic activity while boosting respiratory activity and pyruvate levels,indicating that C.pyrenoidosa used exogenous Ala for biomass accumulation through the respiratory metabolic process.The accelerated respiratory metabolism due to Ala supplementation elevated the substrate pool and improved the lipogenic gene expression,promoting lipid production at last.This study provided a novel method for increasing biomass accumulation and lipid production and elucidated the role of Ala in regulating lipid production.

关键词： alanine Chlorella pyrenoidosa lipid respiration lipogenic gene

Analysis of crack propagation in concrete structures with structural information entropy

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Science China(Technological Sciences) 2010年第7期53卷 1943-1948页

作者： BAO TengFei1’2, PENG Yan1’2, CONG PeiJiang1’2 & WANG JiaLin1’2 1 State Key Laboratory of Hydrology-Water Resources and Hydraulic Engineering, hohai university, Nanjing 210024, China 2 National Engineering Research Center ofWater Resources Efficient Utilization and Engineering Safety, hohai university, Nanjing 210024, China State Key Laboratory of Hydrology-Water Resources and Hydraulic Engineering Hohai University Nanjing China National Engineering Research Center of Water Resources Efficient Utilization and Engineering Safety Hohai University Nanjing China

The propagation of cracks in concrete structures causes energy dissipation and release, and also causes energy redistribution in the structures. Entropy can characterize the energy redistribution. To investigate the relation between the propagation of cracks and the entropy in concrete structures, cracked concrete structures are treated as dissipative structures. Structural information entropy is defined for concrete structures. A compact tension test is conducted. Meanwhile, numerical simulations are also carried out. Both the test and numerical simulation results show that the structural information entropy in the structures can characterize the propagation of cracks in concrete structures.

关键词： crack entropy concrete sun

INFLUENCE OF SEEPAGE FACE OBLIQUITY ON DISCHARGE OF GROUNDWATER AND ITS POLLUTANT INTO LAKE FROM A TYPICAL UNCONFINED AQUIFER

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Journal of Hydrodynamics 2007年第6期19卷 756-761页

作者： LI Yong WANG Chao YANG Lin-zhang LI Yi-ping State Key Laboratory of Hydrology-Water Resources and Hydraulic Engineering Hohai University Nanjing 210098 China College of Environmental Science and Engineering Hohai University Nanjing 210098 China Institute of Soil Science Chinese Academy of Sciences Nanjing 210008 China

Lab experiment and mathematical simulation Modular three dimensional finite difference groundwater （MODFLOW） were performed in a soil tank to simulate the hydrogeochemical interaction between lake and typical unconfined aquifer. Results show that the velocity decreases exponentially with the transect distance on seepage face. The maximal velocity occurs at the top point of seepage face. The obliquity of seepage face has a great influence on the maximum and distribution of seepage velocity. With the increase of the obliquity of seepage face, the maximal velocity decreases quickly and the velocity distribution becomes much more even. Most of groundwater flow and pollutant flux discharges through a narrow portion near the top of seepage face. The flow and mass concentrated in the narrow portion increase with the decrease of the obliquity of seepage face. These will benefit to design a reasonable and economical scenario to manage lakeshore and to control the pollution of lake water near lakeshore.

关键词： shallow lake unconfined aquifer groundwater discharge velocity distribution chloride MODFLOW

Dilatancy equation of rockfill material under the true triaxial stress condition

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Science China(Technological Sciences) 2011年第S1期54卷 175-184页

作者： XIAO Yang 1,2,LIU HanLong 1,2,ZHU JunGao 1,2 & SHI WeiCheng 1,3 1 Key Laboratory of Ministry of Education for Geomechanics and Embankment Engineering,hohai university,Nanjing 210098,China 2 Geotechnical Research Institute,hohai university,Nanjing 210098,China 3 School of Civil Engineering and Architecture,Changzhou Institute of Technology,Changzhou 213002,China Key Laboratory of Ministry of Education for Geomechanics and Embankment Engineering Hohai University Nanjing China Geotechnical Research Institute Hohai University Nanjing China School of Civil Engineering and Architecture Changzhou Institute of Technology Changzhou China

Rockfill material is widely used for construction of high rockfill dam due to its facility,economical cost,high strength and effective aseismatic property.It is provoked profoundly to propose a suitable constitutive model for a better application of this material.The dilatancy equation of rockfill material plays a significant role in the constitutive model.For the sake of simplicity,a dilatancy equation is established by the linear least square method on the basis of the rearranged data of rockfill material in the true triaxial tests.Based on the fact that the rearranged data at different initial confining pressures are aligned in a narrow band,the dilatancy behavior of rockfill material is independent of the initial confining pressure.However,different from the initial confining pressure,both the intermediate principal stress ratio and the specimen density exhibit a remarkable influence on the dilatancy behaviors of rockfill material.Furthermore,the predictions of the proposed dilatancy equation are in a good agreement with the rearranged test data of rockfill material at different specimen densities and stress paths.

关键词： rockfill material dilatancy equation true triaxial test density stress path initial confining pressure

Comparative Study on Microstructure and Mechanical Properties of Coarse-grained WC-based Cemented Carbides Sintered with Ultrafine WC or (W+C) as Additives

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Journal of Wuhan university of Technology(Materials Science) 2024年第2期39卷 399-409页

作者：于淞百闵凡路 LI De NOUDEM Guillaume Jacques ZHANG Hailong MA Jichang ZHAO Kui YAO Zhanhu 张建峰 College of Mechanics and Materials Hohai UniversityNanjing 210098China Key Laboratory of Geomechanics and Embankment Engineering Hohai UniversityMinistry of EducationNanjing 210098China CRISMAT-ENSICAEN(UMR-CNRS 6508) Universitéde Caen-Basse-NormandieF-14050 CaenFrance Shaanxi Aeronautic Carbide Tool Co.Ltd. Hanzhong 724200China CCCC Tunnel Engineering Co.Ltd. Beijing 100102China

The effects of ultrafine WC(WC_(UF),0.5μm) or W(1μm) and C(0.3μm)(W+C)_(UF) additives on the densification,microstructure and mechanical properties of coarse-grained cemented carbides were compared systematically.Overall,the cemented carbides with WC_(UF)/(W+C)_(UF) additives are almost fully densification to be higher than 99%,and the average grain size is kept above 2.8μm.The WC_(UF) additive assists grains to(truncated)trigonal prism shape by two dimensional(2D) growth,whereas the(W+C)_(UF) additive assists grains to rounded shape by three dimensional(3D) growth,lowers WC contiguity and increases face-centered-cubic Co.The hardness and bending strength of(75WC_(C)-15WC_(UF))-10Co are 86.6 HRA and 2 272 MPa,respectively,both higher than those of(75WC_(C)-15(W+C)_(UF))-10Co,which could be ascribed to the enhanced densification and unblemished grains.However,the fracture toughness of the(75WC_(C)-15(W+C)_(UF))-10Co is 23.5 MPa·m^(1/2),higher than that of the(75WC_(C)-15WC_(UF))-10Co due to the uniform WC-Co structure and flexible binder phase.

关键词： coarse-grained WC-based cemented carbide ultrafine WC ultrafine(W+C) microstructure mechanical properties