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On the nonlinear dynamic responses of FG-CNTRC beams exposed to aerothermal loads using third-order piston theory
, Article Acta Mechanica ; Volume 229, Issue 6 , 2018 , Pages 2413-2430 ; 00015970 (ISSN) ; Rabiei Beheshti, A ; Sharif University of Technology
Springer-Verlag Wien
2018
Abstract
The purpose of this study is to analyze the nonlinear dynamic responses of functionally graded carbon nanotube-reinforced composite (FG-CNTRC) beams exposed to axial supersonic airflow in thermal environments. The dynamic model of the FG-CNTRC beam is developed with regard to the first-order shear deformation theory incorporating the von Kármán geometrical nonlinearity. The thermomechanical properties of the constituents are assumed to be temperature dependent. The third-order piston theory is adopted to estimate the nonlinear aerodynamic pressure induced by the supersonic airflow. Harmonic differential quadrature method is implemented to discretize the equations of motion in the spatial...
Experimental study of three-dimensional flow field around a complex bridge pier
, Article Journal of Engineering Mechanics ; Volume 136, Issue 2 , 2010 , Pages 143-154 ; 07339399 (ISSN) ; Ataie Ashtiani, B ; Sharif University of Technology
2010
Abstract
In this paper, three-dimensional turbulent flow field around a complex bridge pier placed on a rough fixed bed is experimentally investigated. The complex pier foundation consists of a column, a pile cap, and a 2×4 pile group. All of the elements are exposed to the approaching flow. An acoustic-Doppler velocimeter was used to measure instantaneously the three components of the velocities at different horizontal and vertical planes. Profiles and contours of time-averaged velocity components, turbulent intensity components, turbulent kinetic energy, and Reynolds stresses, as well as velocity vectors are presented and discussed at different vertical and horizontal planes. The approaching...
Scour hole influence on turbulent flow field around complex bridge piers
, Article Flow, Turbulence and Combustion ; Volume 97, Issue 2 , 2016 , Pages 451-474 ; 13866184 (ISSN) ; Ataie Ashtiani, B ; Sharif University of Technology
Springer Netherlands
2016
Abstract
Experimental results of detailed flow measurements using an Acoustic-Doppler Velocimeter (ADV) around a complex bridge pier (CBP) are presented. The pier consists of a column, a pile cap (PC) and a 2×4 pile group. The time-averaged velocities, turbulence intensities, and Reynolds stresses are studied and presented at different horizontal and vertical planes. Streamlines obtained from the velocity fields are used to show the complexity of the flow around the pier. It is shown that the main feature of the flow responsible for the entrainment of the bed sediments is a contracted (pressurized) flow below the PC toward the piles. A deflected flow around the PC and a strong down-flow along its...
Discussion of “Neuro-fuzzy GMDH systems based evolutionary algorithms to predict scour pile groups in clear water conditions” by M. Najafzadeh
, Article Ocean Engineering ; Volume 123 , 2016 , Pages 249-252 ; 00298018 (ISSN) ; Ataie Ashtiani, B ; Sharif University of Technology
Elsevier Ltd
2016
Abstract
The author utilized neuro-fuzzy based group method of data handling (NF-GMDH) to predict the local scour depth around pile groups under clear-water conditions. They collected the datasets from literature. To predict the local scour by using NF-GMDH, nine dimensional parameters were considered to define a functional relationship between input and output variables. The results of NF- GMDH networks were compared with that of the empirical equations. However, the collected datasets for pile group scouring, the method of implementing the empirical formula to calculate scour depth, and using the equation of Sheppard et al. (2004) suggested for single pier to predict local scouring around pile...
Analysis of threshold and incipient conditions for sediment movement
, Article Coastal Engineering ; Volume 55, Issue 5 , 2008 , Pages 423-430 ; 03783839 (ISSN) ; Ataie Ashtiani, B ; Sharif University of Technology
2008
Abstract
Prediction of threshold conditions and incipient motion is the essential issue for the study of sediment transport. This work compares existing empirical threshold curves proposed for Shields diagram, a method based on the concept of probability of sediment movement, and an empirical method based on movability number. These methods are used to predict the incipient motion conditions for experimental runs taken from various studies. Most of the experimental data, used in this work, have not been used before in derivation of alternative formulations for Shields diagram and other methods. The empirical threshold curves based on the Shields entrainment function was the least successful at...
Sub-pixel image registration based on physical forces
, Article 2010 International Conference on Wireless Communications and Signal Processing, WCSP 2010, 21 October 2010 through 23 October 2010, Suzhou ; 2010 ; 9781424475551 (ISBN) ; Ghorbani, S ; Beheshti Shirazi, A. A ; Sharif University of Technology
2010
Abstract
A new method for image registration has been previously proposed by the authors, which the registration is based on physical forces. The registration parameters are translation and rotation. This method assumes images like charged materials that attract each other. In this case, one of the images moves in the same direction as the applied force while the other one is still. The movement of the image continues until the resultant force becomes zero. This approach estimates the registration parameters simultaneously and leading to a better optimized set of registration parameters. The registration error for this method is 1 to 3 pixels. In this paper we aim to develop this method for the...
Experimental investigation of clear-water local scour of compound piers
, Article Journal of Hydraulic Engineering ; Volume 136, Issue 6 , June , 2010 , Pages 343-351 ; 07339429 (ISSN) ; Baratian Ghorghi, Z ; Beheshti, A. A ; Sharif University of Technology
2010
Abstract
Local scour around complex piers under steady clear-water condition was studied experimentally for a variety of configuration, including different sizes and shapes of complex piers. A total of 70 experiments were carried out. Three sets of experiments were performed over the entire range of possible pile cap elevations for complex piers with different geometrical characteristics. The collected data are used to quantify the pile cap elevations that maximize or minimize the local scour depth. Some of the available methodologies to estimate the maximum local scour depth around such complex piers are evaluated. The predictions of the scour depths improved by using the revised methods of...
Vulnerability assessment of urban groundwater resources to nitrate: the case study of Mashhad, Iran
, Article Environmental Earth Sciences ; Volume 76, Issue 1 , 2017 ; 18666280 (ISSN) ; Ataie Ashtiani, B ; Beheshti, A ; Sharif University of Technology
Springer Verlag
2017
Abstract
Groundwater vulnerability assessment of urban areas is a challenging task in the fast trend of urbanization around the globe. This study introduces a new approach for modifying well-known parameters of common vulnerability indexes to adjust them for urban areas. The approach is independent of a specific weighting system. The aquifer of Mashhad city, contaminated by domestic wastewater, is selected as a case in this study. In order to evaluate the aquifer vulnerability due to anthropogenic activities, at first, parameters of depth to groundwater, recharge, land use, and soil are modified based on their basic concepts and their influences on contamination attenuation. Then, the modified...
Numerical simulations of turbulent flow around side-by-side circular piles with different spacing ratios
, Article International Journal of River Basin Management ; Volume 15, Issue 2 , 2017 , Pages 227-238 ; 15715124 (ISSN) ; Ataie Ashtiani, B ; Dashtpeyma, H ; Sharif University of Technology
Taylor and Francis Ltd
2017
Abstract
Numerical simulations of the turbulent flow around single and side-by-side piles at different spacing ratios (centre-to-centre distance to the pile diameter) with flow Reynolds number of 105 on the fixed flat-bed are presented. The calculations are performed using the computational fluid dynamics model, FLOW-3D, which solves the Navier–Stokes equations in three dimensions with a finite-volume method. The numerical results of time-averaged flow patterns around single and side-by-side piles are validated using the available experimental measurements. At the downstream of the single pile, dimensionless vortex shedding frequency (Strouhal number) is estimated as 0.22. The maximum values of bed...
Discussion of “an integrated framework of extreme learning machines for predicting scour at pile groups in clear water condition
, Article Coastal Engineering ; Volume 142 , 2018 , Pages 106-109 ; 03783839 (ISSN) ; Ataie Ashtiani, B ; Beheshti, A ; Sharif University of Technology
2018
Harmonic class loading for damage identification in beams using wavelet analysis
, Article Structural Health Monitoring ; Volume 6, Issue 1 , 2007 , Pages 67-80 ; 14759217 (ISSN) ; Golafshani, A. A ; Beheshti Aval, S. B ; Noori, M ; Sharif University of Technology
2007
Abstract
The harmonic displacement response of a beam is utilized as the input signal function in wavelet analysis. Sudden changes in the spatial variation of transformed response identify the location of damages and defects. The damage incurred causes a change in the stiffness or mass of the beam. This causes a localized singularity which can be identified by a wavelet analysis of the displacement response. In this article, it is shown that using harmonic response is superior to the static deflection response and this approach is more effective in the presence of noise and more sensitive to the versatility of the applied harmonic loads. © 2007 SAGE Publications
An Approach for Keeping Consistency of Models During the Evaluation of Modeling Languages
, M.Sc. Thesis Sharif University of Technology ; Habibi, Jafar (Supervisor)
Abstract
The development of a complex software needs an abstraction mechanism which is called Model Driven Engineering mechanism. In order to have a successful model based process, we need an appropriate tool such as version control systems to support our model-based process. On the other hand, developers need a mechanism to synchronize them with VCS systems. One of the concerns in modeling languages is the compatibility and the consistency of the models and modeling languages during their evaluation. the focus of the former researches was mostly on the consistency of the models during their evaluation, and to this end, lots of approaches have been proposed for keeping the consistency of the models...
Sustainability Assessment of Preventive Maintenance Plans (Case Study: Slurry Seal and Thin Overlay)
, M.Sc. Thesis Sharif University of Technology ; Tabatabaee, Nader (Supervisor)
Abstract
Preventive maintenance strategies have been considered by highway agencies in order to increase pavement service life and to reduce the costs associated with pavement maintenance. Due to the increasing concern regarding promoting sustainable pavements, consideration of the environmental, economic and performance factors in devising preventive maintenance strategies is of great importance.This study contributes to developing a multicriteria decision-making tool for sustainability evaluation of pavement preventive maintenance strategies. The developed tool, PaveSAT, considers the greenhouse gas emission, net present value, and pavement performance to rank preventive maintenance schemes using...
Analysis of Equilibrium Points in Economic Games
, M.Sc. Thesis Sharif University of Technology ; Habibi, Jafar (Supervisor)
Abstract
Nowadays economical issues are greatly taken into consideration. In this project we aim to study a problem of this area, which focuses on the subject of location allocation and pricing strategy for a good supplier. Solution evaluation is done by taking costumer demand into account. This problem has a sequential characteristic. That is players do not take their decisions at the same time. Suppliers should first decide about where and how they plan to provide their goods. On the other hand almost every economical problem have multiple players who play with or against each other. Therefore modeling this problem using Stackelberg leadership model is a natural choice. Since this problem is in the...
Three dimensional analysis of an AC electric arc furnace
, Article IECON Proceedings (Industrial Electronics Conference), 3 November 2009 through 5 November 2009 ; 2009 , Pages 3697-3702 ; Nazari, A ; Ataei, M ; Khademhosseini Beheshti, H ; Karimi, H ; Sharif University of Technology
2009
Abstract
AC electric arc furnaces (EAFs) highly reduce power quality of the network by generating disturbances such as flicker and harmonics. These disturbances are due to the nonlinear electromagnetic and thermal field behaviors of the AC arcs. Analysis of these nonlinear behaviors is required for improving power quality in the network. This paper presents a three-dimensional finite element modeling of the electromagnetic fields in an AC three-phase electric arc furnace. The model includes the electrodes, arcs and molten bath. Current density, voltage and magnetic field intensity in the arcs, molten bath and electrodes are predicted as a result of applying the three-phase AC voltages to the EAF....
Nonlinear seismic behavior of elliptic-braced moment resisting frame using equivalent braced frame
, Article Steel and Composite Structures ; Volume 40, Issue 1 , 2021 , Pages 45-64 ; 12299367 (ISSN) ; Haghollahi, A ; Talebi Kalaleh, M ; Beheshti Aval, B ; Sharif University of Technology
Techno-Press
2021
Abstract
Recently, the elliptic-braced moment resisting frame (ELBRF) which is a new lateral bracing system installed in the middle bay of the frame in the facade of buildings is introduced. This system not only prevents a solution for opening space problem in view of architectural aspects, but also improves the structural behavior. The main drawback of its using in view of numerical modeling in multistory buildings is lack of curved frame element in design and analysis software. To overcome this shortcoming, in this paper, for the first time, an equivalent element for elliptic brace is presented for ELBRF through a laboratory program and nonlinear finite element analysis, which will contribute to...
Whole-genome analysis of de novo somatic point mutations reveals novel mutational biomarkers in pancreatic cancer
, Article Cancers ; Volume 13, Issue 17 , 2021 ; 20726694 (ISSN) ; Mohseni, A ; Dashti, H ; Beheshti, A ; Dehzangi, A ; Rabiee, H. R ; Alinejad Rokny, H ; Sharif University of Technology
MDPI
2021
Abstract
It is now known that at least 10% of samples with pancreatic cancers (PC) contain a causative mutation in the known susceptibility genes, suggesting the importance of identifying cancer-associated genes that carry the causative mutations in high-risk individuals for early detection of PC. In this study, we develop a statistical pipeline using a new concept, called gene-motif, that utilizes both mutated genes and mutational processes to identify 4211 3-nucleotide PC-associated gene-motifs within 203 significantly mutated genes in PC. Using these gene-motifs as distinguishable features for pancreatic cancer subtyping results in identifying five PC subtypes with distinguishable phenotypes and...
Prediction of current-induced local scour around complex piers: Review, revisit, and integration
, Article Coastal Engineering ; Volume 133 , 2018 , Pages 43-58 ; 03783839 (ISSN) ; Ataie Ashtiani, B ; Beheshti, A ; Hadjzaman, M ; Jamali, M ; Sharif University of Technology
Elsevier B.V
2018
Abstract
Complex piers (CPs), consisting of a column, pile cap and pile group, are commonly built as foundations for hydraulic and marine structures. Scour-hole development around CPs is studied in this paper. A total of 52 tests is carried out on 4 CP models, with experiments durations ranging from 24 to 120 h. All of the available experimental data for clear-water scour around CPs including the collected data of the present study and those previously published are reviewed and combined into a database. A special case of bridge piers with deep foundation or caisson instead of pile caps is also considered, which is herein called compound piers. The database contains 367 experiments for CPs and 162...
Continuous solid-state fermentation as affected by substrate flow pattern
, Article Chemical Engineering Science ; Volume 61, Issue 8 , 2006 , Pages 2675-2687 ; 00092509 (ISSN) ; Mitchell, D. A ; Beheshti, M ; Roostaazad, R ; Sánchez, L. R ; Sharif University of Technology
2006
Abstract
The performance of continuous solid state bioreactors having two different solid substrate flow patterns, namely plug flow and completely mixed flow, is quantified for both steady-state and transient operation using a simple mathematical model. The core assumption is that each substrate particle acts as an infinitesimal bioreactor. The residence time distribution of the particles is considered in the formulation of the equations for the mixed-flow bioreactor and the error that results from neglecting it is investigated by comparing the simulation results with those of a completely mixed, continuous bioreactor for submerged liquid fermentation (a chemostat). The model is extended to include...
Designing and implementing basic sciences ontology based on concepts and relationships of relevant thesauri
, Article Iranian Journal of Information Processing Management ; Volume 30, Issue 3 , Nov , 2015 , Pages 677-696 ; 22518223 (ISSN) ; Ejei, F ; Sharif University of Technology
Iranian Research Institute for Scientific Information and Documentation
2015
Abstract
Currently, the main portion of knowledge is stored in electronic texts and documents and for transferring that knowledge effectively, we must use proper methods to gather and retrieve relevant information. Ontologies provide means to produce structured documents and use intelligent search instead of keyword search. Ontology defines the common words and concepts used to describe and represent an area of knowledge. However, developing ontologies is a time consuming and labor work. So, many ontology developers try to facilitate and speed up this process by reusing other resources. In fact, thesaurus contains semantic information and hierarchical structure that make it an appropriate resource...