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Investigation of Generalized SIFs of cracks in 3D piezoelectric media under various crack-face conditions

Frontiers of Structural and civil engineering 2020年第2期14卷 280-298页

作者： Jaroon RUNGAMORNRAT Bounsana CHANSAVANG Weeraporn PHONGTINNABOOT Chung Nguyen VAN Applied Mechanics and Structures Research Unit Department of Civil EngineeringFaculty of EngineeringChulalongkorn UniversityBangkok 10330Thailand Department of civil engineering Faculty of EngineeringSouphanouvong UniversityLoungprabang 06000Laos Department of civil engineering Faculty of EngineeringBurapha UniversityChonburi 20131Thailand faculty of civil engineering Ho Chi Minh City of Technology and EducationHo Chi Minh 721400Vietnam

This paper investigates the influence of crack geometry,crack-face and loading conditions,and the permittivity of a medium inside the crack gap on intensity factors of planar and non-planar cracks in linear piezoelectric media.A weakly singular boundary integral equation method together with the near-front approximation is adopted to accurately determine the intensity *** results indicate that the non-flat crack surface,the electric field,and the permittivity of a medium inside the crack gap play a crucial role on the behavior of intensity *** mode-I stress intensity factors(K1)for two representative non-planar cracks under different crack-face conditions are found significantly different and they possess both upper and lower *** addition,K1 for impermeable and semi-permeable non-planar cracks treated depends strongly on the electric field whereas those of impermeable,permeable,and semi-permeable penny-shaped cracks are identical and independent of the electric *** stress/electric intensity factors predicted by permeable and energetically consistent models are,respectively,independent of and dependent on the electric field for the penny-shaped crack and the two representative non-planar ***,the permittivity of a medium inside the crack gap strongly affects the intensity factors for all crack configurations considered except for K1 of the semi-permeable pennyshaped crack.

关键词： crack-face conditions intensity factors non-flat cracks permittivity piezoelectric media SGBEM

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Lattice models of traffic flow considering drivers' delay in response

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Chinese Physics B 2009年第4期18卷 1322-1327页

作者：祝会兵 faculty of Architectural Civil Engineering and Environment Ningbo University

This paper proposes two lattice traffic models by taking into account the drivers＇ delay in response. The lattice versions of the hydrodynamic model are described by the differential-difference equation and difference-difference equation, respectively. The stability conditions for the two models are obtained by using the linear stability theory. The modified KdV equation near the critical point is derived to describe the traffic jam by using the reductive perturbation method, and the kink-antikink soliton solutions related to the traffic density waves are obtained. The results show that the drivers＇ delay in sensing headway plays an important role in jamming transition.

关键词： lattice hydrodynamic model traffic jams analytical method drivers' delay in response

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Dynamic failure analysis of concrete dams under air blast using coupled Euler-Lagrange finite element method

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Frontiers of Structural and civil engineering 2019年第1期13卷 15-37页

作者： Farhoud KALATEH faculty of civil engineering University of TabrizTabriz ***Iran

In this study,the air blast response of the concrete dams including dam-reservoir interaction and acoustic cavitation in the reservoir is *** finite element (FE)developed code are used to build three-dimensional (3D)finite element models of concrete dams.A fully coupled Euler-Lagrange formulation has been adopted herein.A previous developed model including the strain rate effects is employed to model the concrete material behavior subjected to blast *** addition,a one-fluid cavitating model is employed for the simulation of acoustic cavitation in the fluid domain.A parametric study is conducted to evaluate the effects of the air blast loading on the response of concrete dam ***,the analyses are performed for different heights of dam and different values of the charge distance from the charge *** results revealed that 1)concrete arch dams are more vulnerable to air blast loading than concrete gravity dams;2)reservoir has mitigation effect on the response of concrete dams;3)acoustic cavitation intensify crest displacement of concrete dams.

关键词： air blast loading concrete dams finite element dam-reservoir interaction cavitation concrete damage model

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Theoretical study on setup of expanded-base pile considering cavity contraction

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Journal of Central South University 2015年第11期22卷 4355-4365页

作者：齐昌广刘干斌王艳邓岳保 faculty of Architectural Civil Engineering and Environment Ningbo University

When an expanded-base pile is installed into ground, the cavity expansion associated with penetration of the enlarged pile base is followed by cavity contraction along the smaller-diameter pile shaft. In order to account for the influence of cavity contraction on the change of bearing capacity of expanded-base pile, a theoretical calculation methodology, predicting the setup of expanded-base pile, was established by employing the cavity contraction theory to estimate the shaft resistance of expanded-base pile, and horizontal consolidation theory to predict the dissipation of excess pore pressure. Finally, the numerical solutions for the setup of expanded-base pile were obtained. The parametric study about the influence of cavity contraction on setup of expanded-base pile was carried out, while a field test was introduced. The parametric study shows that the decrements in radial pressure and the maximum pore water pressure after considering cavity contraction are increased as the expanded ratio(base diameter/shaft diameter) and rigidity index of soil are raised. The comparison between calculated and measured values shows that the calculated results of ultimate bearing capacity for expanded-base pile considering cavity contraction agree well with the measured values; however, the computations ignoring cavity contraction are 2.5-3.0 times the measured values.

关键词： expanded-base pile setup cavity contraction numeri

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Kinetic study on photocatalytic degradation of Acid Orange 52 in a baffled reactor using TiO_2 nanoparticles

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Journal of Environmental Sciences 2019年第5期31卷 213-224页

作者： Payam Zanganeh Ranjbar Bita Ayati Hossein Ganjidoust civil and Environmental engineering faculty Tarbiat Modares University

In this study, a baffled photocatalytic reactor was used for the treatment of colored wastewater containing the azo dye of Acid Orange 52(AO52). A study on the active species of the photocatalytic process using TiO_2 nanoparticles indicated that hydroxyl radical and superoxide have the greatest contribution to the dye degradation process *** that a level of biological oxygen demand/chemical oxygen demand(BOD5/COD) equal to 0.4 was achieved after about 5 hr from the beginning of the experiment, the reactor seems to be capable of purifying the wastewater containing AO52 dye after this time in order to discharge into a biological treatment system to continue the treatment *** results of the liquid chromatography-mass spectrometry(LC-MS) test showed that during the first 4 hr of the experiment, with the breakdown of the azo bond, the contaminant was decomposed into the benzene annular compounds with less toxicity indicating a reduction in the toxicity of wastewater after removing the dye agent. The study on the kinetics of these reactions followed the pseudo-first-order kinetic model in all conditions and corresponded well to Langmuir–Hinshelwood model. According to the kinetic model for the simultaneous occurrence of possible pathways, the kinetic constant of production and degradation of intermediate products in optimal conditions was estimated to be between 0.0029 and 0.0391 min^(-1).

关键词： Kinetic study Active species Photocatalyst Decolorization

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Numerical Modelling Investigation of Wave Interaction on Composite Berm Breakwater

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China Ocean engineering 2021年第5期35卷 631-645页

作者： Seyed Morteza MARASHIAN Mehdi ADJAMI Ahmad Rezaee MAZYAK Water and Environmental engineering Department Faculty of Civil EngineeringShahrood University of TechnologyShahroodIran faculty of civil and Environmental engineering Tarbiat Modares UniversityTehranIran

The breakwaters have experienced many changes during their construction *** changes have been considered to improve their performance,depending on their environmental conditions and *** modelling was conducted using FLOW-3 D *** this study,the wave overtopping from composite berm breakwater as new conceptual structure and the pressure imposed on the composite berm breakwater are considered and *** results show a decrease of 84.01,70.88 and 61.42 percent of the wave overtopping in the composite berm breakwater,in comparison to the rubble mound breakwater,horizontally caisson breakwater and caisson breakwater,***,the pressure applied to the composite berm breakwater with the pressure applied to the horizontally caisson breakwater was compared and *** berm breakwater compared with horizontally caisson breakwater in P1,the amount of the obtained pressure decreased by 52.09%,in P2 the amount of the obtained pressure decreased by 63.07%,in P3 decreased by 76.09%and in Pu,this pressure reduced by53.92%.For the composite berm breakwater,the impact of three types of berms,homogenous berm(Type 1),a berm consisting of armor-filter(Type 2)and multi-layer berm(Type 3)with the aim of optimizing the hydraulic responses and wave interaction on the caisson of the breakwater was examined and *** total,Type 3 will be recommended with a significant reduction in the overtopping values and maximum pressure.

关键词： composite berm breakwater wave interaction berm breakwater wave overtopping pressure rubble mound breakwater horizontally caisson breakwater caisson breakwater

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Fault diagnosis using noise modeling and a new artificial immune system based algorithm

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Earthquake engineering and engineering Vibration 2015年第4期14卷 725-741页

作者： Farshid Abbasi Alireza Mojtahedi Mir Mohammad Ettefagh College of engineering University of Georgia Athens faculty of civil engineering University of Tabriz faculty of Mechanical engineering University of Tabriz

A new fault classification/diagnosis method based on artificial immune system (AIS) algorithms for the structural systems is proposed. In order to improve the accuracy of the proposed method, i.e., higher success rate, Gaussian and non-Gaussian noise generating models are applied to simulate environmental noise. The identification of noise model, known as training process, is based on the estimation of the noise model parameters by genetic algorithms (GA) utilizing real experimental features. The proposed fault classification/diagnosis algorithm is applied to the noise contaminated features. Then, the results are compared to that obtained without noise modeling. The performance of the proposed method is examined using three laboratory case studies in two healthy and damaged conditions. Finally three different types of noise models are studied and it is shown experimentally that the proposed algorithm with non-Gaussian noise modeling leads to more accurate clustering of memory cells as the major part of the fault classification procedure.

关键词： fault diagnosis physical models modal updating AIS method noise modeling

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Dynamic Analysis of Non-Symmetric Functionally Graded (FG) Cylindrical Structure under Shock Loading by Radial Shape Function Using Meshless Local Petrov-Galerkin (MLPG) Method with Nonlinear Grading Patterns

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Computer Modeling in engineering & Sciences 2017年第4期113卷 497-520页

作者： Y.Sadeghi Ferezghi M.R.Sohrabi S.M Mosavi Nezhad civil engineering Department Faculty of EngineeringUniversity of Sistan and BaluchestanZahedanIran civil engineering Department Faculty of EngineeringUniversity of BirjandBirjandIran

In this paper,dynamic behavior of non-symmetric Functionally Graded(FG)cylindrical structure under shock loading is carried *** equations in the polar coordinates are drawn out using Meshless Local Petrov-Galerkin(MLPG)*** volume fractions are used for radial direction to simulate the mechanical properties of Functionally Graded Material(FGM).To solve dynamic equations of nonsymmetric FG cylindrical structure in the time domain,the MLPG method are combined with the Laplace transform *** computing the inverse Laplace transform in the present paper,the Talbot algorithm for the numerical inversion is *** verify the obtained results by the MLPG method,these results are compared with the analytical solution and the Finite Element Method(FEM).The obtained results through the MLPG method show a good agreement in comparison to other results and the MLPG method has high accuracy for dynamic analysis of non-symmetric FG cylindrical *** capability of the present method to dynamic analysis of non-symmetric FG cylindrical structure is demonstrated by dynamic analysis of the cylinder with different volume fraction exponents under harmonic and rectangular shock *** present method shows high accuracy,efficiency and capability to dynamic analysis of non-symmetric FG cylindrical structure with nonlinear grading patterns,which furnishes a ground for a more flexible design.

关键词： MLPG cylindrical structure FGM radial basis functions volume fraction

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Strength,porosity,and chloride resistance of mortar using the combination of two kinds of pozzolanic materials

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International Journal of Minerals,Metallurgy and Materials 2013年第8期20卷 808-814页

作者： Sumrerng Rukzon Prinya Chindaprasirt Department of civil engineering Faculty of EngineeringRajamangala University of Technology Phra Nakhon Sustainable Infrastructure Research and Development Center Department of Civil EngineeringFaculty of EngineeringKhon Kaen University

This article presents a study on the resistance to chloride penetration, corrosion, porosity, and strength of mortar containing fine fly ash （FA）, ground rice husk-bark ash （RB）, and ground bagasse ash （BA）. Ordinary Portland cement （CT） was blended with a single pozzolan and two pozzolans. Strength, porosity, rapid chloride penetration, immersion, and corrosion tests were performed to characterize the mortar. Test results showed that the use of ternary blends of CT, FA, and RB or BA decreased the porosity of the mortar, as compared with binary blended mortar containing CT and RB or BA. The resistance to chloride penetration of the mortar improved substantially with partial replacement of CT with FA, RB, and BA. The use of ternary blends of CT, FA and RB or BA produced the mortar with good strength and resistance to chloride penetration. The resistance to chloride penetration was higher with an increase in the replacement level due to the reduced calcium hydroxide.

关键词： mortar pozzolanic materials strength porosity chloride penetration agricultural wastes

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Chitosan-praseodymium complex for adsorption of fluoride ions from water

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Journal of Rare Earths 2015年第10期33卷 1104-1113页

作者： Eny Kusrini Nofrijon Sofyan Nyoman Suwartha Gefin Yesya Cindy Rianti Priadi Department of Chemical engineering Faculty of Engineering Universitas Indonesia Department of Metallurgical and Materials engineering Faculty of Engineering Universitas Indonesia Department of civil engineering Faculty of Engineering Universitas Indonesia

engineering of chitosan by praseodymium has been investigated to improve the adsorption properties as well as physical characteristics of chitosan. Modification of chitosan changes the original properties of chitosan so that it can be more suitable for adsorption of fluoride ions. In this study, chitosan-praseodymium （Chi-Pr） was synthesized by impregnation method. The Chi-Pr complex was characterized by scanning electron microscopic-energy dispersive X-ray spectroscopy （SEM-EDX）, Fourier transform infrared （FTIR） and employed as an adsorbent for removal of fluorides ions from water in the batch system. The variables such as contact time, concentration of Pr, adsorbent dose, initial concentration of fluoride ions, and competitor anions were studied. The adsorption efficiency of fluoride ions （n） with increasing Pr loading into chitosan （5 wt.%, 10 wt.%, 15 wt.%, 20 wt.% and 25 wt.%） were 35.5%, 56.1%, 72.0%, 68.5% and 62.5%, respectively. The Chi-Pr （15 wt.%） complex had the highest fluoride removal efficiency （72.0%）. The experimental data fitted well to the Langmuir isotherm with maximum adsorption capacity （qmax） of 15.87 mg/g and an equilibrium constant （kL） of 0.15 mg. Kinetic study revealed that the adsorption of fluoride ions from water followed pseudo-second-order model with a maximum adsorption capacity （q2） of 8.20 mg/g and a rate constant （k2） of 0.01 g/***. Adsorption efficiency of fluoride ions in the simulated drinking water was diminished with the changes in pH levels. The presence of Pr3＋ in chitosan increased chitosan＇s performance as an adsorbent for adsorption of fluoride ions.

关键词： adsorption of fluoride chitosan isotherms studies kinetics study praseodymium rare earths

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