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Neural network and neuro-fuzzy assessments for scour depth around bridge piers
, Article Engineering Applications of Artificial Intelligence ; Volume 20, Issue 3 , 2007 , Pages 401-414 ; 09521976 (ISSN) ; Borghei, S. M ; Jeng, D. S ; Sharif University of Technology
2007
Abstract
The mechanism of flow around a pier structure is so complicated that it is difficult to establish a general empirical model to provide accurate estimation for scour. Interestingly, each of the proposed empirical formula yields good results for a particular data set. Hence, in this study, alternative approaches, artificial neural networks (ANNs) and adaptive neuro-fuzzy inference system (ANFIS), are proposed to estimate the equilibrium and time-dependent scour depth with numerous reliable data base. Two ANN models, multi-layer perception using back-propagation algorithm (MLP/BP) and radial basis using orthogonal least-squares algorithm (RBF/OLS), were used. The equilibrium scour depth was...
Optimizing floor reservation and contention resolution in wireless random access
, Article Ad Hoc Networks ; Volume 82 , 2019 , Pages 31-45 ; 15708705 (ISSN) ; Golestani, S. J ; Doost Hoseini, A. M ; Sharif University of Technology
Elsevier B.V
2019
Abstract
In this paper, we propose a novel wireless random access scheme, combining the CSMA/CA mechanism with two control signals for initiating new transmissions and announcing receiver busy status, respectively. We also develop a time-space framework of performance analysis, enabling separate study of the temporal and spatial efficiency of the random access, i.e. the scheme's ability for contention resolution and efficient performance in time, and its ability to provide for concurrent transmissions in space. Based on this framework and using both analysis and simulation, we show that the proposed scheme outperforms the IEEE 802.11 DCF, in terms of the overall afforded throughput, and also in terms...
Geotechnical characteristics of copper mine tailings: A case study
, Article Geotechnical and Geological Engineering ; Volume 25, Issue 5 , 2007 , Pages 591-602 ; 09603182 (ISSN) ; Pak, A ; Bateni, S. M ; Ayatollahi, S. A. H ; Sharif University of Technology
2007
Abstract
Waste management issue in mining industry has become increasingly important. In this regard, construction of tailings dams plays a major role. Most of the tailings dams require some kinds of remedial actions during their operational lifetime, among which heightening is the most common. In the first stage of the remedial provisions for Sarcheshmeh Copper Complex tailings dam in Iran, it has been decided to use hydrocyclone method to provide suitable construction material due to the high cost associated with using borrow materials for heightening of the dam. To undertake this project a series of laboratory experiments was performed to determine the copper 'original tailings' and 'cycloned...
Evaluation of methods for estimating aquifer hydraulic parameters
, Article Applied Soft Computing Journal ; Volume 28 , March , 2015 , Pages 541-549 ; 15684946 (ISSN) ; Mortazavi Naeini, M ; Ataie Ashtiani, B ; Jeng, D. S ; Khanbilvardi, R ; Sharif University of Technology
Elsevier Ltd
2015
Abstract
An accurate estimation of aquifer hydraulic parameters is required for groundwater modeling and proper management of vital groundwater resources. In situ measurements of aquifer hydraulic parameters are expensive and difficult. Traditionally, these parameters have been estimated by graphical methods that are approximate and time-consuming. As a result, nonlinear programming (NLP) techniques have been used extensively to estimate them. Despite the outperformance of NLP approaches over graphical methods, they tend to converge to local minima and typically suffer from a convergence problem. In this study, Genetic Algorithm (GA) and Ant Colony Optimization (ACO) methods are used to identify...
Plane embeddings of planar graph metrics
, Article Discrete and Computational Geometry ; Volume 38, Issue 3 , 2007 , Pages 615-637 ; 01795376 (ISSN) ; Demaine, E. D ; Hajiaghayi, M ; Moharrami, M ; Sharif University of Technology
Springer New York
2007
Abstract
Embedding metrics into constant-dimensional geometric spaces, such as the Euclidean plane, is relatively poorly understood. Motivated by applications in visualization, ad-hoc networks, and molecular reconstruction, we consider the natural problem of embedding shortest-path metrics of unweighted planar graphs (planar graph metrics) into the Euclidean plane. It is known that, in the special case of shortest-path metrics of trees, embedding into the plane requires Θ(√n) distortion in the worst case [M1], [BMMV], and surprisingly, this worst-case upper bound provides the best known approximation algorithm for minimizing distortion. We answer an open question posed in this work and highlighted by...
The cooperative game theory foundations of network bargaining games
, Article Lecture Notes in Computer Science (including subseries Lecture Notes in Artificial Intelligence and Lecture Notes in Bioinformatics), 6 July 2010 through 10 July 2010, Bordeaux ; Volume 6198 LNCS, Issue PART 1 , 2010 , Pages 67-78 ; 03029743 (ISSN) ; 3642141641 (ISBN) ; Hajiaghayi, M ; Immorlica, N ; Mahini, H ; Sharif University of Technology
2010
Abstract
We study bargaining games between suppliers and manufacturers in a network context. Agents wish to enter into contracts in order to generate surplus which then must be divided among the participants. Potential contracts and their surplus are represented by weighted edges in our bipartite network. Each agent in the market is additionally limited by a capacity representing the number of contracts which he or she may undertake. When all agents are limited to just one contract each, prior research applied natural generalizations of the Nash bargaining solution to the networked setting, defined the new solution concepts of stable and balanced, and characterized the resulting bargaining outcomes....
Diffusion-based nanonetworking: A new modulation technique and performance analysis
, Article IEEE Communications Letters ; Volume 17, Issue 4 , 2013 , Pages 645-648 ; 10897798 (ISSN) ; Gohari, A ; Kenari, M. N ; Bateni, F ; Sharif University of Technology
2013
Abstract
In this letter, a new molecular modulation scheme for nanonetworks is proposed. To evaluate the scheme, a system model based on the Poisson distribution is introduced. The error probability of the proposed scheme as well as that of two previously known schemes, the concentration and molecular shift keying modulations, are derived for the Poisson model by taking into account the error propagation effect of previously decoded symbols. The proposed scheme is shown to outperform the previously introduced schemes. This is due to the fact that the decoding of the current symbol in the proposed scheme does not encounter propagation of error, as the decoding of the current symbol does not depend on...
Reducing occupant injury in frontal crashes for a low-floor city bus
, Article 2005 ASME International Mechanical Engineering Congress and Exposition, IMECE 2005, Orlando, FL, 5 November 2005 through 11 November 2005 ; Volume 2006 , 2006 , Pages 113-120 ; Darvish, K ; Parnianpour, M ; Bateni, A ; Sharif University of Technology
2006
Abstract
In this research, the effect of beam buckling in a predefined direction is used to reduce occupant injuries in frontal crashes of an ultra-low-floor (ULF) city bus. In ULF buses, the floor structure consists of several longitudinal long beams, which in case of a frontal crash may buckle due to the axial impact. The direction of rotational acceleration of the driver seat due to buckling is highly affected by the position of the driver seat. A finite element model of an ULF bus was developed using LS-Dyna. The driver model, a Hybrid III 50 th male dummy with deformable jacket and abdomen, was restrained to the seat with a 3-point belt. An Elastic-Plastic material model was used for the bus...
Plane embeddings of planar graph metrics
, Article 22nd Annual Symposium on Computational Geometry 2006, SCG'06, Sedona, AZ, 5 June 2006 through 7 June 2006 ; Volume 2006 , 2006 , Pages 197-206 ; 1595933409 (ISBN); 9781595933409 (ISBN) ; Demaine, E. D ; Hajiaghayi, M ; Moharrami, M ; ACM SIGACT; ACM SIGGRAPH ; Sharif University of Technology
Association for Computing Machinery
2006
Abstract
Embedding metrics into constant-dimensional geometric spaces, such as the Euclidean plane, is relatively poorly understood. Motivated by applications in visualization, ad-hoc networks, and molecular reconstruction, we consider the natural problem of embedding shortest-path metrics of unweighted planar graphs (planar graph metrics) into the Euclidean plane. It is known that, in the special case of shortest-path metrics of trees, embedding into the plane requires Θ(√n) distortion in the worst case [19, 1], and surprisingly, this worst-case upper bound provides the best known approximation algorithm for minimizing distortion. We answer an open question posed in this work and highlighted by...
Non-fragile control and synchronization of a new fractional order chaotic system
, Article Applied Mathematics and Computation ; Volume 222 , 2013 , Pages 712-721 ; 00963003 (ISSN) ; Delshad, S. S ; Hamidi Beheshti, M. T ; Tavazoei, M. S ; Sharif University of Technology
2013
Abstract
In this paper, we address global non-fragile control and synchronization of a new fractional order chaotic system. First we inspect the chaotic behavior of the fractional order system under study and also find the lowest order (2.49) for the introduced dynamics to remain chaotic. Then, a necessary and sufficient condition which can be easily extended to other fractional-order systems is proposed in terms of Linear Matrix Inequality (LMI) to check whether the candidate state feedback controller with parameter uncertainty can guarantee zero convergence of error or not. In addition, the proposed method provides a global zero attraction of error that guarantees stability around all existing...
Parameters calculation of transformer winding detailed model based on finite element method to study partial discharge
, Article International Review on Modelling and Simulations ; Volume 5, Issue 5 , October , 2012 , Pages 1995-2000 ; 19749821 (ISSN) ; Vakilian, M ; Enjavimadar, S. M ; Sharif University of Technology
Praise Worthy Prize
2012
Abstract
The first step to locate Partial Discharge in power transformers is to find a model that can clearly explain the behavior of the winding in high-frequency. The detailed model is one of the models used for the study of PD. One of the fundamental problems of the described model is to find its parameters. And the accuracy in calculating these parameters has significant impact on reducing the simulation error and PD locating. The current paper seeks to calculate the parameters of the detailed model 20kv distribution transformer winding by using the finite element method (FEM). Comparing the results of this model with pulse waveforms obtained from the PD to the winding in the laboratory...
A Mechanical model for flexible exercise bars to study the influence of the initial position of the bar on lumbar discs and muscles forces
, Article Proceedings of the Annual International Conference of the IEEE Engineering in Medicine and Biology Society, EMBS, 25 August 2015 through 29 August 2015 ; Volume 2015-November , 2015 , Pages 3917-3920 ; 1557170X (ISSN) ; 9781424492718 (ISBN) ; Abdollahi, M ; Nikkhoo, M ; Hoviattalab, M ; Asghari, M ; Ashouri, S ; Nikpour, S ; Kahrizi, S ; Parnianpour, M ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2015
Abstract
A single-degree-of-freedom model is considered for flexible exercise bars based on the lumped-element approach. By considering the side segment of a flexible bar as a cantilever beam with an equivalent mass at the free end, its free-vibration response, as well as the forced response under the excitation of the grip, are expressed parametrically. Experiments are performed on a particular flexible bar (FLEXI-BAR) in order to obtain numerical values for quantifying the model's parameters. The model is also computationally simulated to study the response of the flexible bar to various excitations. The results are imported into a multi-segment musculoskeletal software (AnyBody), where the effect...
Magnetoelectric nanocomposite scaffold for high yield differentiation of mesenchymal stem cells to neural-like cells
, Article Journal of Cellular Physiology ; Volume 234, Issue 8 , 2019 , Pages 13617-13628 ; 00219541 (ISSN) ; Soleimani, M ; Ghiass, M. A ; Hatamie, S ; Vakilian, S ; Zomorrod, M. S ; Sadeghzadeh, N ; Vossoughi, M ; Hosseinzadeh, S ; Sharif University of Technology
Wiley-Liss Inc
2019
Abstract
While the differentiation factors have been widely used to differentiate mesenchymal stem cells (MSCs) into various cell types, they can cause harm at the same time. Therefore, it is beneficial to propose methods to differentiate MSCs without factors. Herein, magnetoelectric (ME) nanofibers were synthesized as the scaffold for the growth of MSCs and their differentiation into neural cells without factors. This nanocomposite takes the advantage of the synergies of the magnetostrictive filler, CoFe 2 O 4 nanoparticles (CFO), and piezoelectric polymer, polyvinylidene difluoride (PVDF). Graphene oxide nanosheets were decorated with CFO nanoparticles for a proper dispersion in the polymer through...
Hydrogenated graphene oxide (H-G-SiO2) Janus structure: Experimental and computational study of strong piezo-electricity response
, Article Journal of Physics D: Applied Physics ; Volume 53, Issue 17 , 2020 ; Alidoosti, M ; Hosseinzadeh, A ; Seyyedi, S. M. S ; Elahi, M ; Pourfath, M ; Mohajerzadeh, S ; Sharif University of Technology
Institute of Physics Publishing
2020
Abstract
We have investigated the piezoelectric response of the hydrogenated graphene oxide (H-G-SiO2) stacks both experimentally and theoretically. The piezoresponse force microscopy method and density-functional theory (DFT) calculations were used to study the piezoresponse effect of this structure from both experimental and computational point of views. A mono-layer graphene, made by chemical vapour deposition method, is deposited on Si/SiO2 substrate and its surface is then functionalized with hydrogen atoms. The vertical piezoresponse, observed by piezoresponse force microscopy, is measured to be about 2146 pC N-1, that is comparable to the reported state of the art piezoelectric materials such...
An ultra-wideband 3-dB quadrature hybrid with multisection broadside stripline tandem structure
, Article Lecture Notes of the Institute for Computer Sciences, Social-Informatics and Telecommunications Engineering ; Volume 77 LNICST , 2012 , Pages 672-681 ; 18678211 (ISSN) ; 9783642351549 (ISBN) ; Majedi, S. M. S ; Farzaneh, F ; Sharif University of Technology
2012
Abstract
Design of an Ultra-Wideband 3-dB quadrature (90°) Hybrid using ADS and HFSS softwares plus Measurement report are presented. Simultaneous Use of these two softwares lead to fast and accurate design procedure. The coupler is realized in broadside stripline and with the connection of coupled regions in tandem structure. The measured data agrees well with the expected values from simulations, and shows a good ultra wide bandwidth response over the frequency range of 1-10 GHz. Measurements showed an amplitude unbalance of ±1.5 dB, a phase unbalance of 90°±7° , and an isolation and a return loss characteristics of more than 14 dB over the frequency of 1 to 10 GHz
Broadside coupler Channels 1 to 10 GHz
, Article Microwaves and RF ; Volume 51, Issue 1 , 2012 ; 07452993 (ISSN) ; Majedi, S. M. S ; Farzaneh, F ; Sharif University of Technology
2012
Tensile deformation mechanisms at different temperatures in the Ni-base superalloy GTD-111
, Article Journal of Materials Processing Technology ; Volume 155-156, Issue 1-3 , 2004 , Pages 1900-1904 ; 09240136 (ISSN) ; Nategh, S ; Isac, M ; Zebarjad, S. M ; Sharif University of Technology
2004
Abstract
The Ni-base superalloy GTD-111 is employed in high-power stationary gas turbines because of its high temperature strength and oxidation resistance. The temperature dependence of the tensile behavior of GTD-111 has been studied by tensile tests in the temperature range of 25-900°C with a constant strain rate of 10-4s-1. The results showed an abnormal tensile property variation with increasing temperature. The yield strength decreased slightly with temperature up to about 650°C and then increased between 650 and 750°C. Above 750°C, a rapid decrease in the yield strength was found. The tensile strength showed a similar behavior except for its maximum that occurred at 650°C. The elongation...
Cell-imprinted substrates act as an artificial niche for skin regeneration
, Article ACS Applied Materials and Interfaces ; Vol. 6, Issue. 15 , 2014 , Pages 13280-13292 ; ISSN: 19448244 ; Bonakdar, S ; Taghinejad, H ; Satarifard, V ; Heidari, M ; Majidi, M ; Sharifi, S ; Peirovi, A ; Saffar, S ; Taghinejad, M ; Abdolahad, M ; Mohajerzadeh, S ; Shokrgozar, M. A ; Rezayat, S. M ; Ejtehadi M. R ; Dalby, M. J ; Mahmoudi, M ; Sharif University of Technology
2014
Abstract
Bioinspired materials can mimic the stem cell environment and modulate stem cell differentiation and proliferation. In this study, biomimetic micro/nanoenvironments were fabricated by cell-imprinted substrates based on mature human keratinocyte morphological templates. The data obtained from atomic force microscopy and field emission scanning electron microscopy revealed that the keratinocyte-cell-imprinted poly(dimethylsiloxane) casting procedure could imitate the surface morphology of the plasma membrane, ranging from the nanoscale to the macroscale, which may provide the required topographical cell fingerprints to induce differentiation. Gene expression levels of the genes analyzed...
Development of grid resource discovery service based on semantic information
, Article SpringSim '07: Proceedings of the 2007 spring simulaiton multiconference ; Volume 1 , 2007 , Pages 141-148 ; 07359276 (ISSN) ; 1565553128 (ISBN); 9781565553125 (ISBN) ; Moshkenani, M. S ; Sharif University of Technology
2007
Abstract
Grid computing is a type of parallel and distributed system that provides the possibility of sharing, choosing and collecting the autonomous resources (such as computer, software, databases, and equipments) that are distributed geographically. Resource discovery is one of the key subjects in distributed systems and especially Grids. We should consider that Grid consists of different applications that each of them consist of different hardware and software resources, therefore recognizing these resources is important in a Grid system. Classical approaches to Grid resource discovery are either centralized or hierarchical [1] (and will maybe prove inefficient as the scale of Grid systems...
Effect of nanoclay on improved rheology properties of polyacrylamide solutions used in enhanced oil recovery
, Article Journal of Petroleum Exploration and Production Technology ; Volume 5, Issue 2 , June , 2015 , Pages 189-196 ; 21900558 (ISSN) ; Khalili Nezhad, S. S ; Kamari, M ; Hemmati, M ; Masihi, M ; Bazgir, S ; Sharif University of Technology
Springer Verlag
2015
Abstract
Recently, a renewed interest arises in the application of nanotechnology for the upstream petroleum industry. In particular, adding nanoparticles to fluids may drastically benefit enhanced oil recovery (EOR) and improve well drilling, by changing the properties of the fluid, rocks wettability alteration, advanced drag reduction, strengthening the sand consolidation, reducing the interfacial tension and increasing the mobility of the capillary trapped oil. In this study, we focus on roles of clay nano-particles on polymer viscosity. Polymer-flooding schemes for recovering residual oil have been in general less than satisfactory due to loss of chemical components by adsorption on reservoir...