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Effect of seismic wave propagation in massed medium on rate-dependent anisotropic damage growth in concrete gravity dams

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Frontiers of Structural and Civil Engineering 2021年第2期15卷 346-363页

作者： alireza DANESHYAR Hamid MOHAMMADNEZHAD Mohsen GHAEMIAN Civil Engineering Department Sharif University of TechnologyTehran11155-9313Iran Faculty of Civil Water and Environmental EngineeringShahid Beheshti UniversityTehran11155-9313Iran

Seismic modeling of massive structures requires special caution,as wave propagation effects significantly affect the *** becomes more crucial when the path-dependent behavior of the material is *** coexistence of these conditions renders numerical earthquake analysis of concrete dams ***,a finite element model for a comprehensive nonlinear seismic simulation of concrete gravity dams,including realistic soil-structure interactions,is introduced.A semi-infinite medium is formulated based on the domain reduction method in conjunction with standard viscous *** representation of radiation damping in a half-space medium and wave propagation effects in a massed foundation are verified using an analytical solution of vertically propagating shear waves in a viscoelastic half-space domain.A rigorous nonlinear finite element model requires a precise description of the material ***,a microplane-based anisotropic damage-plastic model of concrete is formulated to reproduce irreversible deformations and tensorial degeneration of concrete in a coupled and rate-dependent ***,the Koyna concrete gravity dam is analyzed based on different assumptions of foundation,concrete response,and reservoir *** between responses obtained based on conventional assumptions with the results of the presented comprehensive model indicates the significance of considering radiation damping and employing a rigorous constitutive material model,which is pursued for the presented model.

关键词： soil-structure interaction massed foundation radiation damping anisotropic damage

Experimental study of path planning problem using EMCOA for a holonomic mobile robot

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Journal of Systems Engineering and Electronics 2021年第6期32卷 1450-1462页

作者： MOHSENI alireza DUCHAINE Vincent WONG Tony Department of System Engineering École de Technologie SupérieureMontreal QC H3C 1K3Canada

In this paper,a comparative study of the path planning problem using evolutionary algorithms,in comparison with classical methods such as the A*algorithm,is presented for a holonomic mobile *** configured navigation system,which consists of the integration of sensors sources,map formatting,global and local path planners,and the base controller,aims to enable the robot to follow the shortest smooth path ***-based mapping is used for scoring paths efficiently,allowing the determination of collision-free trajectories from the initial to the target *** work considers the evolutionary algorithms,the mutated cuckoo optimization algorithm(MCOA)and the genetic algorithm(GA),as a global planner to find the shortest safe path among others.A non-uniform motion coefficient is introduced for MCOA in order to increase the performance of this algorithm.A series of experiments are accomplished and analyzed to confirm the performance of the global planner implemented on a holonomic mobile *** results of the experiments show the capacity of the planner framework with respect to the path planning problem under various obstacle layouts.

关键词： holonomic robot path planning evolutionary algorithm(EA)

Non-Monotonic Lyapunov-Krasovskii Functional Approach to Stability Analysis and Stabilization of Discrete Time-Delay Systems

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IEEE/CAA Journal of Automatica Sinica 2020年第3期7卷 752-763页

作者： Younes Solgi alireza Fatehi Ala Shariati Advanced Process Automation and Control Research Group Industrial Control Center of ExcellenceFaculty of Electrical EngineeringK.N.Toosi University of TechnologyTehran 16317-14191Iran IEEE

In this paper, a novel non-monotonic Lyapunov-Krasovskii functional approach is proposed to deal with the stability analysis and stabilization problem of linear discrete time-delay systems. This technique is utilized to relax the monotonic requirement of the Lyapunov-Krasovskii theorem. In this regard, the Lyapunov-Krasovskii functional is allowed to increase in a few steps, while being forced to be overall decreasing. As a result, it relays on a larger class of Lyapunov-Krasovskii functionals to provide stability of a state-delay system. To this end, using the non-monotonic Lyapunov-Krasovskii theorem, new sufficient conditions are derived regarding linear matrix inequalities(LMIs)to study the global asymptotic stability of state-delay ***, new stabilization conditions are also proposed for time-delay systems in this article. Both simulation and experimental results on a p H neutralizing process are provided to demonstrate the efficacy of the proposed method.

关键词： Linear matrix inequality(LMI) non-monotonic Lyapunov-Krasovskii functional(NMLKF) pH neutralization plant stabilization state-delay system time-delay system

Effect of seismic waves on the hydro-mechanical properties of fractured rock masses

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Earthquake Engineering and Engineering Vibration 2017年第3期16卷 525-536页

作者： Meysam Lak alireza Baghbanan Hamid Hashemolhoseini Department of Mining Engineering Isfahan University of Technology (IUT) Isfahan Iran Department of Civil Engineering Isfahan University of Technology (IUT) Isfahan Iran

The transmission of seismic waves in a particular region may influence the hydraulic properties of a rock mass, including permeability, which is one of the most important. To determine the effect of a seismic wave on the hydraulic behavior of a fractured rock mass, systematic numerical modeling was conducted. A number of discrete fracture network（DFN） models with a size of 20 m × 20 m were used as geometrical bases, and a discrete element method（DEM） was employed as a numerical simulation tool. Three different boundary conditions without（Type Ⅰ） and with static（Type Ⅱ） and dynamic（Type Ⅲ） loading were performed on the models, and then their permeability was calculated. The results showed that permeability in Type Ⅲ models was respectively 62.7% and 44.2% higher than in Type I and Type Ⅱ models. This study indicates that seismic waves can affect deep earth, and, according to the results, seismic waves increase the permeability and change the flow rate patterns in a fractured rock mass.

关键词： wave transmission earthquake dynamic analysis discrete fracture network permeability UDEC

Landfill site selection using multi cr iter ia decision making: Influential factors for comparing locations

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Journal of Environmental Sciences 2020年第7期32卷 170-184页

作者： Yashar Rezaeisabzevar alireza Bazargan Behzad Zohourian School of Environment College of EngineeringUniversity of Tehran141785311 TehranIran Department of Engineering Ferdowsi University of Mashhad*** MashhadIran

Although a lot of research has focused on energy recovery and recycling of valuable materials from wastes to reduce loads on landfills,landfilling is still an inseparable part of solid waste *** landfills potentially pose a risk to human health and the surrounding environment,landfill site selection is an important endeavor that has to be carried out with great *** a suitable location for landfills depends on several factors and is a complicated *** this paper,a comprehensive review of landfill site selection methods,with an emphasis on multi criteria decision making(multiple criteria decision analysis)has been *** indicate that the most frequently used methods are weighted linear combination(WLC),ordered weighted averaging(OWA),analytic hierarchy process(AHP),fuzzy analytic hierarchy process(F-AHP),TODIM,fuzzy TODIM,analytic network process(ANP),fuzzy-analytic network process(F-ANP),and grey systems theory,each of which is *** most widely used factors for selecting a landfill site are groundwater depth,surface water vicinity,elevation,land slope,soil permeability,soil stability,flooding susceptibility,lithology and stratification,faults,land use type,nearby settlements and urbanization,cultural and protected site vicinity,wind direction,roads,railways,proximity to building materials,pipelines and powerlines,and proximity to airports.

关键词： Sustainable urban planning Waste management Sanitary landfills Landfill siting Geographic information system

Design of Tunable Devices at Terahertz Frequencies Based on Quasi-Photonic Crystals Incorporated with Graphene

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Communications in Theoretical Physics 2019年第10期71卷 1227-1235页

作者： Reza Ghayoor alireza Keshavarz Department of Physics Shiraz University of Technology

In this study, we present a new theoretical model including Thue-Morse and double-period sequences as quasi-photonic crystals are incorporation with graphene and investigate the transmission properties of the THz waves in both structures using a straightforward computational method. We also consider properties of nonlinear conductivity in addition to surface linear conductivity for graphene. We observe the sharp peaks and proper forbidden bands are created in the range of 0.3 THz to 30 THz. In addition, we find that by considering the nonlinear term of graphene and engineering the structural parameters such as the chemical potential of graphene, number of layers and the incidence wave angle, transmission levels of peaks enhance scientifically and quality factor improve considerably. These results show that it would be possible to design of high-Q tunable filters with multi-stop bands in the THz regime which can reduce the noise associated with THz frequency peaks and increase the number of sharp frequency peaks.

关键词： graphene nonlinear conductivity terahertz filters transfer matrix transmission spectrum

Segregation behavior of a ternary mixture of titanium dioxide particles in a pseudo two-dimensional fluidized bed

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Particuology 2021年第1期19卷 78-90页

作者： Mojtaba Rasteh alireza Bahramian Goodarz Ahmadi Department of Chemical Engineering Hamedan University of TechnologyHamedanP.O.Box65155-579Iran Department of Mechanical and Aeronautical Engineering Clarkson UniversityPotsdamNY 13699-5725USA

The segregation behavior of a mixture of silica-coated titanium dioxide(TiO2)particles of three different sizes in a pseudo two-dimensional fluidized bed was studied experimentally by the freeze-sieving method and numerically by the multi-fluid model(MFM).Three-dimensional computational fluid dynamics(CFD)simulations were carried out to evaluate the effects of the solid wall boundary conditions on particle segregation in terms of specularity and particle-wall restitution *** quantitative indexes of segregation tendency and segregation degree were used to determine the axial segregation of the mixture in triangular *** simulation results revealed that the axial segregation increased with the specularity coefficient,whereas the particle-wall restitution coefficient had a minor effect on axial *** of the simulation results with experimental data showed that the appropriate value of the specularity coefficient used in the CFD model depended on superficial gas *** study of the effects of superficial gas velocity on segregation behavior demonstrated that the greatest segregation was obtained at minimum fluidization velocity and the segregation decreased as the gas velocity gradually increased.

关键词： Ternary mixture Segregation tendency Segregation degree Two-fluid model Computational fluid dynamics(CFD)

Characterization of Operators on the Dual of Hypergroups which Commute with Translations and Convolutions

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Acta Mathematica Sinica,English Series 2004年第2期20卷 201-208页

作者： Ali Ghaffari alireza Medghalchi Department of Mathematics Semnan UniversityP.O.Box 35195-363SemnanIran Department of Mathematics Teacher Training UniversityTehranIran.

For a locally compact group G, L 1(G) is its group algebra and L ∞(G) is the dual of L 1(G). Lau has studied the bounded linear operators T : L ∞(G) → L ∞(G) which commute with convolutions and translations. For a subspace H of L ∞(G), we know that M(L ∞(G),H), the Banach algebra of all bounded linear operators on L ∞(G) into H which commute with convolutions, has been studied by Pym and Lau. In this paper, we generalize these problems to L(K)*, the dual of a hypergroup algebra L(K) in a very general setting, i. e. we do not assume that K admits a Haar measure. It should be noted that these algebras include not only the group algebra L 1(G) but also most of the semigroup algebras. Compact hypergroups have a Haar measure, however, in general it is not known that every hypergroup has a Haar measure. The lack of the Haar measure and involution presents many difficulties; however, we succeed in getting some interesting results.

关键词： Hypergroup algebras Group algebras Operators Translations Convolutions Invariant

Strength evolution and deformation behaviour of cemented paste backfill at early ages： Effect of curing stress, filling strategy and drainage

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International Journal of Mining Science and Technology 2016年第5期26卷 809-817页

作者： Ghirian alireza Fall Mamadou Department of Civil Engineering University of Ottawa 161 Louis Pasteur Ottawa K1N 6N5 ON Canada

In this study, a pressure cell apparatus is developed to investigate the early age evolution of the strength and deformation behaviour of cemented paste backfill(CPB) when subjected to various loading conditions under different curing scenarios. The different curing scenarios that are simulated include:(1)drained and undrained conditions,(2) different filling rates,(3) different filling sequences, and(4) different curing stresses. The findings show that drainage, curing stress, curing time and filling rate influence the mechanical and deformation behaviours of CPB materials. The coupled effects of consolidation, drainage and suction contribute to the strength development of drained CPB subjected to curing stress. On the other hand, particle rearrangement caused by the applied pressure and suction development due to self-desiccation plays a significant role in the strength gain of undrained CPB cured under ***, curing stress induces slightly faster rate of cement hydration, which can contribute to strength acquisition.

关键词： Cemented paste backfill Tailings Pore pressure Curing under stress Plug fill Cement