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Experimental investigation on the aerodynamic performance of NLF-0414 iced-airfoil
, Article Journal of Applied Fluid Mechanics ; Volume 9, Issue 2 , 2016 , Pages 587-592 ; 17353572 (ISSN) ; Hajipour, M ; Hasheminasab, H ; Sharif University of Technology
Isfahan University of Technology
2016
Abstract
Icing phenomenon on a natural laminar flow airfoil (NLF-0414) has been experimentally investigated. Double horn glaze ice geometry which was acquired during a 15 minutes spray time at-2.23°C with liquid water content and a median volumetric diameter of 1.0 g/m3 and 20 μm, has been extracted from database of NASA Lewis Research Center. Pressure distribution over airfoil surfacewas evaluated at angles of attack between -2 to 6 degreesfor both iced and clean airfoils. Aerodynamics performance degradation of the iced airfoil has been studied and it is shown that double horn ice accretion, due to its unique geometry, severely affects aerodynamic characteristics of natural laminar flow airfoils....
Causes of common and frequent claims in oil, gas and petrochemical projects of Iran
, Article KSCE Journal of Civil Engineering ; Volume 18, Issue 5 , June , 2014 , Pages 1270-1278 ; ISSN: 12267988 ; Mortaheb, M. M ; Ahmadian, F. F. A ; Sharif University of Technology
2014
Abstract
Over recent years, frequent involvements in claims have been inevitable due to unpredictable economic changes and increasing complexities in construction industry. Therefore, even appropriately made contracts are not exempted from claims. On the other hand, construction contract claims are time-consuming, expense-involving and most likely leading to unsatisfactory results. However, there may be some positive outcomes, such as time extension or compensation of damages. To launch investigations, a list of important and frequent claims in oil and gas industry projects of Iran was extracted after a succinct documents review. Further, the most important claim causes were identified through...
Estimation of water coverage ratio in low temperature PEM-fuel cell using deep neural network
, Article IEEE Sensors Journal ; Volume 20, Issue 18 , May , 2020 , Pages 10679-10686 ; Alasty, A ; Boroushaki, M ; Khodsiani, M. H ; Hasheminasab, M. R ; Kermani, M. J ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2020
Abstract
Proton exchange membrane fuel cell (PEMFC) is a rich source of renewable energy. A non-destructive prediction method is needed to determine the content of water in the PEMFC. In the gas channel of a transparent PEMFC, water is detected with image processing. This method has a high computational cost and is sensitive to the initial position of the camera and ambient lighting. In this paper, the deep neural network (DNN) has been trained to learn the transparent PEMFC's labeled images as a way to determine the content of water, limit human interference and employed in a real-time process. This DNN model is a virtual sensor for measuring the water coverage ratio. To produce the label of images,...
Claims Prevention Management & Counter Claim Management in Oil Industry Projects of Iran
, M.Sc. Thesis Sharif University of Technology ; Ebrahimi, Nasrollah (Supervisor) ; Mortaheb, Mohammad Mehdi (Supervisor)
Abstract
In recent years, frequent involvements in claims have been inevitable due to unpredictable economic changes and increasing complexities in construction industry. Therefore, even appropriately made contracts are not exempted from claims. On the other hand, construction contract claims are time-consuming, expense-involving and most likely leading to unsatisfactory results. However, there may be some positive outcomes, such as time extension or compensation of damages. To launch investigationson claim management, a list of important and frequent claims in oil and gas industry projects of Iran was extracted after a succinct documents review. Further, the most important claim causes were...
Application of decision tree, artificial neural networks, and adaptive neuro-fuzzy inference system on predicting lost circulation: A case study from Marun oil field
, Article Journal of Petroleum Science and Engineering ; Volume 177 , 2019 , Pages 236-249 ; 09204105 (ISSN) ; Talebkeikhah, M ; Agin, F ; Talebkeikhah, F ; Hasheminasab, E ; Sharif University of Technology
Elsevier B.V
2019
Abstract
One of the most prevalent problems in drilling industry is lost circulation which causes intense increase in drilling expenditure as well as operational obstacles such as well instability and blowout. The aim of this research is to develop smart systems for estimating amount of lost circulation making able to use appropriate prevention and remediation methods. To obtain this aim, a large data set were collected from 61 recently drilled wells in Marun oil field in Iran to be used for developing relevant models. After that, using the extracted data set consisting of 1900 data subset, intelligent prediction models including decision tree (DT), adaptive neuro-fuzzy inference systems (ANFIS),...
Child Effect on Female Employment: Evidence from Iran with a Structural Approach
, M.Sc. Thesis Sharif University of Technology ; Keshavarz Haddad, Gholamreza (Supervisor) ; Moeini, Safoura (Supervisor)
Abstract
This research answers two questions: First, what effect does the increase in the number of children have on women's employment? Second, what is the magnitude of the effect of increasing the number of children on the potential employment rate of Iranian women? To address the first question, we use Heckman's reduced form regression along with a structural model of female labor supply. We use the Simulated Method Moments (SMM) to estimate the structural equations. Our data for the empirical analysis are taken from the Iranian Households’ Income and Expenditures Surveys in urban areas over the years 1990 to 2020. We use the estimated model to measure the potential increase in female employment...
Trajectory following of a micro motion stage based on closed-loop FEM simulation
, Article ASME International Mechanical Engineering Congress and Exposition, IMECE 2007, Seattle, WA, 11 November 2007 through 15 November 2007 ; Volume 11 PART A , 2008 , Pages 155-158 ; 079184305X (ISBN); 9780791843055 (ISBN) ; Mahboobi, S. H ; Pirouzpanah, S ; Esteki, H ; Sarkar, S ; Sharif University of Technology
2008
Abstract
Micro motion stages are one of the essential components in field of micro robotics and ultra fine positioning systems. This research presents the optimum design of a 3-DOF micro motion stage and its position control using FEM simulation. This stage to be studied uses a 3 RRR flexure hinge base compliant mechanism driven by three piezoelectric stack actuators to provide micro scale planar motion. First of all parametric modeling of the stage will be fulfilled in ANSYS environment utilizing a commercial piezostack and different types of flexure hinges. Hence the Jacobian matrix will be achieved for each case. The optimum selection of the hinge form will be achieved upon results of the previous...
Ricci-based chaos analysis for roto-translatory motion of a Kelvin-type gyrostat satellite
, Article Proceedings of the Institution of Mechanical Engineers, Part K: Journal of Multi-body Dynamics ; Vol. 228, issue. 1 , 2014 , pp. 34-46 ; ISSN: 14644193 ; Sadati, S. H ; Salarieh, H ; Sharif University of Technology
2014
Abstract
The chaotic dynamics of roto-translatory motion of a triaxial Kelvin-type gyrostat satellite under gravity gradient perturbations is considered. The Hamiltonian approach is used for modelling of the coupled spin-orbit equations of motion. The complex Hamiltonian of the system is reduced via the extended Deprit canonical transformation using the Serret- Andoyer variables. Therefore, this reduction leads to the derivation of the perturbation form of the Hamiltonian that can be used in the Ricci curvature criterion based on the Riemannian manifold geometry for the analysis of chaos phenomenon. The results obtained from Ricci method as well as the values from the Lyapunov exponent demonstrate...
Improving ITIL strategic alignment approach using COBIT framework
, Article Proceedings of the International Conference on Electronic Business (ICEB), 1 December 2010 through 4 December 2010, Shanghai ; 2010 , Pages 490-494 ; 16830040 (ISSN) ; Gardesh, H ; Sikari, S. S ; Sharif University of Technology
2010
Abstract
IT Governance provides a business focus to enable alignment between business and IT objectives at high level COBIT framework and focused on IT operational levels, ITIL standard. COBIT and ITIL are not mutually exclusive and can be combined to provide a powerful IT governance, control and best-practice framework in IT service management. So ITIL business-IT strategic alignment perspective could be improved using COBIT framework. Focusing on COBIT processes which support (primarily and secondarily) strategic alignment, in this paper, first, we map COBIT 4.1 to ITIL v3 to identify how ITIL cover COBIT control objectives. Furthermore, based on control objectives which are not completely...
Nonlinear analysis and attitude control of a gyrostat satellite with chaotic dynamics using discrete-time LQR-OGY
, Article Asian Journal of Control ; 2016 ; 15618625 (ISSN) ; Sadati, S. H ; Salarieh, H ; Sharif University of Technology
Wiley-Blackwell
2016
Abstract
Quasi-periodic and chaotic behavior, along with the control of chaos for a Gyrostat satellite (GS), is investigated in this work. The quaternion-based dynamical model of the GS is first derived, and then the influences of the reaction wheels in the GS structure, under the gravity gradient perturbation that causes a route to chaos through quasi-periodicity mechanism, is investigated. For the suppression of chaos in the system, a chaos control system with the quaternion feedback is designed for the GS based on the extension of the Ott-Grebogi-Yorke (OGY) method using the linearization of the Poincaré map. In the extended OGY controller, the Poincaré map is estimated using the Least Square...
Experimental identification of closely spaced modes using NExT-ERA
, Article Journal of Sound and Vibration ; Volume 412 , 2018 , Pages 116-129 ; 0022460X (ISSN) ; Momeni Massouleh, S. H ; Hajirezayi, S ; Bahai, H ; Sharif University of Technology
Academic Press
2018
Abstract
This article presents a study on the capability of the time domain OMA method, NExT-ERA, to identify closely spaced structural dynamic modes. A survey in the literature reveals that few experimental studies have been conducted on the effectiveness of the NExT-ERA methodology in case of closely spaced modes specifically. In this paper we present the formulation for NExT-ERA. This formulation is then implemented in an algorithm and a code, developed in house to identify the modal parameters of different systems using their generated time history data. Some numerical models are firstly investigated to validate the code. Two different case studies involving a plate with closely spaced modes and...
Trajectory following of a micro motion stage based on closedloop fem simulation
, Article ASME 2007 International Mechanical Engineering Congress and Exposition, IMECE 2007, 11 November 2007 through 15 November 2007 ; Volume 11 , 2007 , Pages 155-158 ; 079184305X (ISBN) ; Mahboobi, S. H ; Pirouzpanah, S ; Esteki, H ; Sarkar, S ; ASME ; Sharif University of Technology
American Society of Mechanical Engineers (ASME)
2007
Abstract
Micro motion stages are one of the essential components in field of micro robotics and ultra fine positioning systems. This research presents the optimum design of a 3-DOF micro motion stage and its position control using FEM simulation. This stage to be studied uses a 3 RRR flexure hinge base compliant mechanism driven by three piezoelectric stack actuators to provide micro scale planar motion. First of all parametric modeling of the stage will be fulfilled in ANSYS environment utilizing a commercial piezostack and different types of flexure hinges. Hence the Jacobian matrix will be achieved for each case. The optimum selection of the hinge form will be achieved upon results of the previous...
Iterative histogram matching algorithm for chromosome image enhancement based on statistical moments
, Article Proceedings - International Symposium on Biomedical Imaging ; 2012 , Pages 214-217 ; 19457928 (ISSN) ; 9781457718588 (ISBN) ; Mousavi, H. S ; Khalaj, B. H ; Sharif University of Technology
IEEE
2012
Abstract
Vivid banding pattern of the chromosome image is a crucial part for diagnosis in karyotype medical test. Furthermore, thriving computer aided segmentation and classification depend on the initial image quality. In this paper, we propose an adaptive and iterative histogram matching algorithm for chromosome contrast enhancement especially in banding patterns which is one of the most important information laid in chromosome image. Objective histogram, with which the initial image needs to be matched, is created based on processes on the initial image histogram. Calculation of statistical moments of image histogram and determination of parameters in each step of iteration based on these moments...
Chromosome image contrast enhancement using adaptive, iterative histogram matching
, Article 2011 7th Iranian Conference on Machine Vision and Image Processing, MVIP 2011 - Proceedings, 16 November 2011 through 17 November 2011 ; 2011 ; 9781457715358 (ISBN) ; Mousavi, H. S ; Khalaj, B. H ; Sharif University of Technology
2011
Abstract
Vivid banding patterns in medical images of chromosomes are a vital feature for karyotyping and chromosome classification. The chromosome image quality may be degraded by many phenomenon such as staining, sample defectness and imaging conditions. Thus, an image enhancement processing algorithm is needed before classification of chromosomes. In this paper, we propose an adaptive and iterative histogram matching (AIHM) algorithm for chromosome contrast enhancement especially in banding patterns. The reference histogram, with which the initial image needs to be matched, is created based on some processes on the initial image histogram. Usage of raw information in the histogram of initial image...
Energy saving in HVAC systems using nanofluid
, Article Applied Thermal Engineering ; Volume 31, Issue 8-9 , 2011 , Pages 1543-1545 ; 13594311 (ISSN) ; Soltanieh, M ; Noie, S. H ; Saidi, S. H ; Sharif University of Technology
2011
Abstract
The present study tries to use the methanol-silver nanofluid filled thermosyphon heat exchanger and compares the effectiveness as well as energy saving with pure methanol. Experimental results show that using methanol-silver nanofluid, leads to energy saving around 8.8-31.5% for cooling and 18-100% for reheating the supply air stream in an air conditioning system
The large-scale dynamic maximal covering location problem
, Article Mathematical and Computer Modelling ; Volume 57, Issue 3-4 , February , 2013 , Pages 710-719 ; 08957177 (ISSN) ; Davari, S ; Sisakht, S. A. H ; Sharif University of Technology
2013
Abstract
Most of the publications regarding the maxim covering location problem (MCLP) address the case where the decision is to be made for one period. In this paper, we deal with a rather untouched version of MCLP which is called dynamic MCLP (DMCLP). In order to solve this problem, a simulated annealing (SA) has been presented. The proposed solution algorithm is capable of solving problems with up to 2500 demand nodes and 200 potential facilities with a fair amount of exactness. Our experiments showed that the proposed approach finds solutions with errors less than one percent
Alginate/cartilage extracellular matrix-based injectable interpenetrating polymer network hydrogel for cartilage tissue engineering
, Article Journal of Biomaterials Applications ; Volume 36, Issue 5 , 2021 , Pages 803-817 ; 08853282 (ISSN) ; Mashayekhan, S ; Pazooki, H ; Mohsenifard, S ; Baniasadi, H ; Sharif University of Technology
SAGE Publications Ltd
2021
Abstract
In the present study, alginate/cartilage extracellular matrix (ECM)-based injectable hydrogel was developed incorporated with silk fibroin nanofibers (SFN) for cartilage tissue engineering. The in situ forming hydrogels were composed of different ionic crosslinked alginate concentrations with 1% w/v enzymatically crosslinked phenolized cartilage ECM, resulting in an interpenetrating polymer network (IPN). The response surface methodology (RSM) approach was applied to optimize IPN hydrogel's mechanical properties by varying alginate and SFN concentrations. The results demonstrated that upon increasing the alginate concentration, the compression modulus improved. The SFN concentration was...
Adiabatic shear banding in an Al-Mg-Si alloy processed by equal channel angular pressing
, Article Materials Science Forum, 2 August 2010 through 6 August 2010, Cairns, QLD ; Volume 654-656 , 2010 , Pages 1014-1017 ; 02555476 (ISSN) ; 0878492550 (ISBN) ; Taheri, A. K ; Yoo, J. H ; Joo, S. H ; Kim, H. S ; Sharif University of Technology
2010
Abstract
Equal channel angular pressing is an outstanding method for imposing large plastic deformation to metallic materials without any decreasing in cross section area of as processed samples. In this paper, the effect of working temperature, ram speed and the number of passes on the formation of adiabatic shear bands in Al6061 during equal channel angular pressing was investigated. Billets of the alloy were processed up to four passes via route BC from room temperature to 200°C with two ram speeds using a die that imparts an effective strain of ∼1.1 per pass. The results have demonstrated that the onset of the adiabatic shear banding in this alloy strongly depends on the ram speed: more...
The gardener problem with reservation policy and discount
, Article Computers and Industrial Engineering ; Volume 123 , 2018 , Pages 82-102 ; 03608352 (ISSN) ; Pasandideh, S. H. R ; Akhavan Niaki, S. T ; Nahavandian, M. H ; Sharif University of Technology
Elsevier Ltd
2018
Abstract
The Newsboy problem has always been an important issue in inventory management. The multi-product newsboy problem with random yield and budget constraint named as the Gardener Problem is one of the novels and popular extensions of the newsboy problem. Different from the existing studies, this paper presents a multi-product gardener problem with reservation policy. Moreover, a discount rate is offered to those customers who are willing to make reservations. In addition to the demand from the original customers, extra demand is included in the model due to the motivation received by the discount rate. A solution algorithm namely the multi-product gardener problem with reservation policy...
Anisotropy in the quasi-static and cyclic behavior of ZK60 extrusion: Characterization and fatigue modeling
, Article Materials and Design ; Volume 160 , 2018 , Pages 936-948 ; 02641275 (ISSN) ; Karparvarfard, S. M. H ; Shaha, S. K ; Behravesh, S. B ; Adibnazari, S ; Jahed, H ; Sharif University of Technology
Elsevier Ltd
2018
Abstract
The quasi-static and strain-controlled fatigue characteristics of ZK60 extrusion have been investigated along three different directions: the extrusion direction (ED), the radial direction (RD), and 45° to the extrusion direction (45°). The quasi-static response showed symmetric behavior for the samples tested along RD and 45° whereas the ED samples manifested completely asymmetric behavior. Although the ED samples exhibited longer fatigue lives than the RD and 45° in the high cycle fatigue, the fatigue lives in the low cycle fatigue regime were similar. The texture measurement indicated a sharp basal texture along ED, explaining its asymmetric behavior. Higher tensile mean stress and less...