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Journal of Environmental Sciences 2019年第7期31卷 181-194页

作者： arash Mollahosseini Amira Abdelrasoul Department of Chemical and Biological Engineering University of Saskatchewan Global Institute of Water Security

Drinking water scarcity is an ever-increasing global concern. This issue appears as a greater threat to the countries with no access to sea water resources or rivers, since their potential water resources are only limited to ground waters only. There are serious concerns with the treatment of ground water resources, including landfill leachates, agricultural contaminations(pesticides,herbicides, and fertilizers), and rural contaminations. Membrane separation has been proved to be the governing technology in water and wastewater treatment plants, as these methods are responsible for more than half of the market share of the world's desalination capacity. This study intends to offer a holistic view of the groundwater contamination with specific focus on Saskatchewan province in Canada, and the recent efforts in the groundwater treatment using thin film composite membrane technology. This study begins with an introduction of the general aspects of ground water and membrane separation, polluting agents, and their *** is followed by a discussion of Saskatchewan's groundwater status and various ***, the recent research that became available since 2010 is reviewed in details and the results are summarized with respect to purification efficiency. Different affecting parameters in a groundwater-thin film composite system are synthesized and an in-depth overview is presented.

关键词： Thin film composite membrane Groundwater Brackish water Water pollution Polyamide Canada Saskatchewan

Buckling analysis of functionally graded plates partially resting on elastic foundation using the differential quadrature element method

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Acta Mechanica Sinica 2019年第1期35卷 174-189,I0005页

作者： arash Shahbaztabar Koosha Arteshyar Department of Ocean Engineering AmirKabir University of TechnologyTehran 15914Iran Department of Mechanical Engineering Islamic Azad UniversityKarajAlborzIran

We extend the differential quadrature element method (DQEM) to the buckling analysis of uniformly in-plane loaded functionally graded (FG) plates fully or partially resting on the Pasternak model of elastic support. Material properties of the FG plate are graded in the thickness direction and assumed to obey a power law distribution of the volume fraction of the constituents. To set up the global eigenvalue equation, the plate is divided into sub-domains or elements and the generalized differential quadrature procedure is applied to discretize the governing, boundary and compatibility equations. By assembling discrete equations at all nodal points, the weighting coefficient and force matrices are derived. To validate the accuracy of this method, the results are compared with those of the exact solution and the finite element method. At the end, the effects of different variables and local elastic support arrangements on the buckling load factor are investigated.

关键词： Differential quadrature element method Pasternak elastic support Critical buckling load Functionally graded plates

Optimal design of double-layer barrel vaults using genetic and pattern search algorithms and optimized neural network as surrogate model

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Frontiers of Structural and Civil Engineering 2023年第3期17卷 378-395页

作者： Reza JAVANMARDI Behrouz ahmadi-NEDUSHAN Department of Civil Engineering Yazd UniversityYazd 89195Iran

This paper presents a combined method based on optimized neural networks and optimization algorithms to solve structural optimization *** main idea is to utilize an optimized artificial neural network(OANN)as a surrogate model to reduce the number of computations for structural ***,the OANN is trained ***,the main optimization problem is solved using the OANN and a population-based *** algorithms considered in this step are the arithmetic optimization algorithm(AOA)and genetic algorithm(GA).Finally,the abovementioned problem is solved using the optimal point obtained from the previous step and the pattern search(PS)*** evaluate the performance of the proposed method,two numerical examples are *** the first example,the performance of two algorithms,OANN+AOA+PS and OANN+GA+PS,is *** the GA reduces the elapsed time by approximately 50%compared with using the *** show that both the OANN+GA+PS and OANN+AOA+PS algorithms perform well in solving structural optimization problems and achieve the same optimal ***,the OANN+GA+PS algorithm requires significantly fewer function evaluations to achieve the same accuracy as the OANN+AOA+PS algorithm.

关键词： optimization surrogate models artificial neural network SAP2000 genetic algorithm

Effect of glycine-starch mixing ratio on the structural characteristics of MgAl2O4 nano-particles synthesized by sol-gel combustion

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Particuology 2016年第1期14卷 108-112页

作者： arash Motevalian Shiva Salem Faculty of Chemical Engineering Urrnia University of Technology Urrnia lran

Sol-gel auto-ignition was used to prepare nano-scale magnesium aluminate spinel, using nitrate salts as an oxidizer and glycine-starch mixtures as the fuel. The glycine-starch mixture was varied to understand the effect of fuel mixing ratio on the structural characteristics of the resulting magnesium aluminate. The products were characterized by thermogravimetric-differential thermal analyses, Fourier-transform infrared spectroscopy, X-ray diffraction, Brunauer-Emmett-Teller surface area measurements, and trans- mission electron microscopy. The phase purity and crystallite size of the powder products depended on the fuel mixing ratio. The presence of starch in the fuel facilitated the preparation of pure nano-particles. To prepare nano-particles of uniform spherical morphology and diameter of 〈 13 nm, the starch content should be Ol^timized to avoid agglomeration.

关键词： MgAl2O4 Starch Sol-gel Combustion Nano-particle Agglomeration

An efficient two-stage approach for structural damage detection using meta-heuristic algorithms and group method of data handling surrogate model

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Frontiers of Structural and Civil Engineering 2020年第4期14卷 907-929页

作者： Hamed FATHNEJAT Behrouz ahmadi-NEDUSHAN Department of Civil Engineering Yazd UniversityYazd 89195-741Iran

In this study,the performance of an efficient two-stage methodology which is applied in a damage detection system using a surrogate model of the structure has been *** the first stage,in order to locate the damage accurately,the performance of the modal strain energy based index for using different numbers of natural mode shapes has been evaluated using the confusion *** the second stage,to estimate the damage extent,the sensitivity of most used modal properties due to damage,such as natural frequency and flexibility matrix is compared with the mean normalized modal strain energy(MNMSE)of suspected damaged ***,a modal property change vector is evaluated using the group method of data handling(GMDH)network as a surrogate model during damage extent estimation by optimization algorithm;in this part of methodology,the performance of the three popular optimization algorithms including particle swarm optimization(PSO),bat algorithm(BA),and colliding bodies optimization(CBO)is examined and in this regard,root mean square deviation(RMSD)based on the modal property change vector has been proposed as an objective ***,the effect of noise in the measurement of structural responses by the sensors has also been ***,in order to achieve the most generalized neural network as a surrogate model,GMDH performance is compared with a properly trained cascade feed-forward neural network(CFNN)with log-sigmoid hidden layer transfer *** results indicate that the accuracy of damage extent estimation is acceptable in the case of integration of PSO and ***,the GMDH model is also more efficient and mimics the behavior of the structure slightly better than CFNN model.

关键词： two-stage method modal strain energy surrogate model GMDH optimization damage detection

Free vibration analysis of non-homogeneous orthotropic plates resting on Pasternak elastic foundation by Rayleigh-Ritz method

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Journal of Central South University 2016年第2期23卷 413-420页

作者： Ahmad Rahbar-Ranji arash Shahbaztabar Department of Ocean Engineering Amir Kabir University of Technology

Free vibration analysis of non-homogeneous orthotropic plates resting on a Pasternak type of elastic foundation is investigated. A set of admissible orthogonal polynomials are generated with Gram-Schmidt orthogonalization procedure and adopted in the Rayleigh-Ritz method. Accuracy and applicability of the method are examined by comparison of the results for different boundary conditions and material types with those available in literature. It is found that this method has good accuracy regardless of type of boundary condition and yields very accurate results even with low number of terms of orthogonal polynomials for the first mode of vibration. For higher modes of vibration, higher terms of orthogonal polynomials should be used. The effects of foundation parameter, density and non-homogeneity parameters on natural frequency are examined. It is concluded that natural frequency of plates are more sensitive to shearing layer coefficient rather than Winkler coefficient and density parameter has weakening effect on natural frequency.

关键词： free vibration non-homogeneous orthotropic plate Pastemak foundation Rayleigh-Ritz method Gram-Schmidt procedure

Functional Charge Transfer Plasmon Metadevices

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Research 2020年第1期2020卷 1829-1846页

作者： Burak Gerislioglu arash ahmadivand Department of Physics&Astronomy Rice University6100 Main StHoustonTexas 77005USA Department of Electrical&Computer Engineering Rice University6100 Main StHoustonTexas 77005USA

Reducing the capacitive opening between subwavelength metallic objects down to atomic scales or bridging the gap by a conductive path reveals new plasmonic spectral features,known as charge transfer plasmon(CTP).We review the origin,properties,and trending applications of this modes and show how they can be well-understood by classical electrodynamics and quantum mechanics *** important is the excitation mechanisms and practical approaches of such a unique resonance in tailoring high-response and efficient extreme-subwavelength hybrid nanophotonic *** the quantum tunnelinginduced CTP mode possesses the ability to turn on and off the charge transition by varying the intensity of an external light source,the excited CTP in conductively bridged plasmonic systems suffers from the lack of *** address this,the integration of bulk plasmonic nanostructures with optothermally and optoelectronically controllable components has been introduced as promising techniques for developing multifunctional and high-performance CTP-resonant *** tunable plasmonic devices such as metamodulators and metafilters are thus in prospect.

关键词： CTP conductive extreme

Application of random set method in a deep excavation: based on a case study in Tehran cemented alluvium

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Frontiers of Structural and Civil Engineering 2019年第1期13卷 66-80页

作者： arash SEKHAVATIAN Asskar Janalizadeh CHOOBBASTI Department of Civil Engineering Babol Noshirvani University of TechnologyBabolIran

The design of high-rise buildings often necessitates ground excavation,where buildings are in close proximity to the construction,thus there is a potential for damage to these *** paper studies an efficient user-friendly framework for dealing with uncertainties in a deep excavation in layers of cemented coarse grained soil located in Tehran,Iran by non-deterministic Random Set (RS)*** order to enhance the acceptability of the method among engineers,a pertinent code was written in FISH language of FLAC2D software which enables the designers to run all simulations simultaneously,without cumbersome procedure of changing input variables in every individual *** could drastically decrease the computational effort and cost imposed to the project,which is of great importance especially to the *** results are presented in terms of probability of occurrence and most likely values of the horizontal displacement at top of the wall at every stage of ***,a methodology for assessing the credibility of the uncertainty model is presented using a quality *** was concluded that performing RS analysis before the beginning of every stage could cause great economical savings,while improving the safety of the project.

关键词： uncertainty reliability analysis deep excavations random set method finite difference method

Free Vibration Analysis of Symmetrically Laminated Composite Plates on Elastic Foundation and Coupled with Stationary Fluid

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China Ocean Engineering 2018年第3期32卷 266-277页

作者： arash SHAHBAZTABAR Ahmad RAHBAR-RANJI Department of Ocean Engineering AmirK abir University of Technology

Free vibration analysis of symmetrically laminated composite plates resting on Pasternak elastic support and coupled with an ideal, incompressible and inviscid fluid is the objective of the present work. The fluid domain is considered to be infinite in the length direction but bounded in the depth and width directions. In order to derive the eigenvalue equation, Rayleigh-Ritz method is applied for the fluid-plate-foundation system. The efficiency of the method is proved by comparison studies with those reported in the open literature. At the end, parametric studies are carried out to examine the impact of different parameters on the natural frequencies.

关键词： free vibration analysis laminated composite plate fluid-plate-foundation interaction Rayleigh-Ritz method Pasternak foundation

Effects of Yttrium Addition on Microstructure, Hardness and Resistance to Wear and Corrosive Wear of TiNi Alloy

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Journal of Materials Science & Technology 2011年第9期27卷 851-855页

作者： Hojat ahmadi Meisam Nouri Faculty of Biosystems Engineering University of Tehran Department of Materials Engineering Tarbiat Modares University

TiNi alloy has a high resistance to wear and could be an excellent candidate for various tribological applications. In this paper, it was demonstrated that by addition of yttrium, hardness properties and resistance to wear and corrosive wear of TiNi alloy were improved. New yttrium rich regions were formed in microstructure of TiNi alloy. The improved properties of this alloy by the yttrium addition could be attributed to the formation of these regions. The results showed that there was an optimum content for addition of yttrium between 2% and 5% （in wt%）, and above this content the improvement in properties of TiNi became minor.

关键词： Yttrium TiNi Mechanical behaviour Wear Corrosive wear Microstructure