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hydraulics
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An investigation on the dynamic response of the shaking table steel deck using finite element
, Article 11th World Congress on Computational Mechanics, WCCM 2014, 5th European Conference on Computational Mechanics, ECCM 2014 and 6th European Conference on Computational Fluid Dynamics, ECFD 2014 ; 2014 , pp. 1330-1340 ; ISBN: 9788494284472 ; Farzanian, K ; Taheri, E ; Sharif University of Technology
Abstract
This paper presents the results of an analytical study on the dynamic characteristics of the Shaking Table facilities at Sharif University. This 3 degree of freedom shaking table is driven by 3 servo-control hydraulic actuators, and consists of a 12 ton, 4m×4m×0.6m steel deck. The main objective of this investigation is to identify the degree of flexibility of the deck, and its adverse effects in causing errors in the simulation of seismic effects on different structural specimens. Many frame specimens of different weights and configurations are subjected to seismic motions, and their responses are calculated using FE models. Some of these models were designed to account for eccentric...
An investigation of fracture geometry in hydraulic fracturing on a gas reservoir well production enhancement
, Article Petroleum Science and Technology ; Vol. 32, issue. 2 , 2014 , pp. 150-157 ; ISSN: 10916466 ; Parvazdavani, M ; Abbasi, S ; Rahnama, A. R ; Sharif University of Technology
Abstract
Utilizing improved production methods have been always challenging in upstream industries. Nowadays, hydraulic fracturing is one of the most prestigious mechanical methods. Application of this method is in wells with low productivity index. Hydraulic fracturing efficiency depends on various factors, such as fracture geometry, fluid composition, and stress distribution. But some of them would be ignored, such as fracture geometry, which is neglected due to nongravity and lack of investigation of DFN statistical population assumption. The authors develop a more comprehensive methodology based on fracture geometry and aim to model one of the gas reservoirs in Iran that is naturally fractured by...
An integrated SPH-polyhedral DEM algorithm to investigate hydraulic stability of rock and concrete blocks: application to cubic armours in breakwaters
, Article Engineering Analysis with Boundary Elements ; Volume 84 , 2017 , Pages 1-18 ; 09557997 (ISSN) ; Pak, A ; Sharif University of Technology
Abstract
In this paper, a combination of the Lagrangian meshfree method of SPH and Polyhedral DEM is presented to simulate the interaction between the free surface of water and solid objects possessing sharp edges and flat surfaces, such as armour units of breakwaters. Both SPH and DEM schemes are validated successfully against experimental data. The numerical scheme is utilized to inspect the stability of concrete cubic armours in rubble-mound breakwaters through systematic analyses with various geometrical parameters and environmental conditions. The numerical results regarding the required dimensions of the cubic blocks for providing stability of the armour units under the wave attack are compared...
An improvement of collision probability in biased birthday attack against A5/1 stream cipher
, Article 2010 European Wireless Conference, EW 2010, 12 April 2010 through 15 April 2010, Lucca ; April , 2010 , Pages 444-448 ; 9781424459995 (ISBN) ; Tavakoli, H ; Naderi, M ; Sharif University of Technology
2010
Abstract
A5/1 is the strong version of the encryption algorithm on GSM (Global System for Mobile communications) used in many countries. It is constructed of a combination of three LFSRs (Linear Feedback Shift Registers) with irregular clocking manner. One of the most practical attacks against this algorithm is time-memory trade-off attack, which is based on birthday paradox. The goal of this attack is to find any intersection between precomputed LFSRs states set and set of states generating the output bits in the actual execution of the algorithm. In order to increase feasibility of this attack, the biased birthday attack was introduced. In this attack special states producing a specific pattern in...
An improved porous media approach to thermal-hydraulics analysis of high-temperature gas-cooled reactors
, Article Annals of Nuclear Energy ; Volume 76 , February , 2015 , Pages 485-492 ; 03064549 (ISSN) ; Tabatabai Ghomsheh, S. I ; Sharif University of Technology
Elsevier Ltd
2015
Abstract
A precise thermal-hydraulics model is of great importance for developing more effective designs of High Temperature Gas Cooled Reactors (HTGR). Recently, several advancements have been made in the methods of analysis of porous media which could be of significant value in the development of more precise and robust codes. The objective of this research is to incorporate some of the most recent improvements in the development of a new 2D program for thermal-hydraulics analysis of modular high temperature reactors. The program is mainly based on the solution of a coupled set of mass, energy and momentum conservation equations for the gas flow, along with the energy conservation equation in the...
An improved methodology for design of custom-made hip prostheses to be fabricated using additive manufacturing technologies
, Article Rapid Prototyping Journal ; Volume 18, Issue 5 , 2012 , Pages 389-400 ; 13552546 (ISSN) ; Abbaszadeh, F ; Farahmand, F ; Sharif University of Technology
Emerald
2012
Abstract
Purpose - The purpose of this paper is to present an improved methodology for design of custom-made hip prostheses, through integration of advanced image processing, computer aided design (CAD) and additive manufacturing (AM) technologies. Design/methodology/approach - The proposed methodology for design of custom-made hip prostheses is based on an independent design criterion for each of the intra-medullary and extra-medullary portions of the prosthesis. The intra-medullar part of the prosthesis is designed using a more accurate and detailed description of the 3D geometry of the femoral intra-medullary cavity, including the septum calcar ridge, so that an improved fill and fit performance...
An improved Kalman filtering approach for the estimation of unsaturated flow parameters by assimilating photographic imaging data
, Article Journal of Hydrology ; Volume 590 , 2020 ; Belfort, B ; Lehmann, F ; Weill, S ; Ataie Ashtiani, B ; Fahs, M ; Sharif University of Technology
Elsevier B.V
2020
Abstract
As a non-invasive method, photographic imaging techniques offer some interesting potentials for characterization of soil moisture content in unsaturated porous media, enabling mapping at very fine resolutions in both space and time. Although less explored, the wealth of soil moisture data provided by photographic imaging is also appealing for the estimation of unsaturated soil hydraulic parameters through inverse modeling. However, imaging data have some unique characteristics, including high susceptibility to noise, which can negatively affect the parameter estimation process. In this study a sequential data assimilation approach is developed to simultaneously update soil moisture content...
Aniline-silica nanocomposite as a novel solid phase microextraction fiber coating
, Article Journal of Chromatography A ; Volume 1238 , May , 2012 , Pages 22-29 ; 00219673 (ISSN) ; Roostaie, A ; Sharif University of Technology
2012
Abstract
A new unbreakable solid phase microextraction (SPME) fiber coating based on aniline-silica nanocomposite was electrodeposited on a stainless steel wire. The electropolymerization process was carried out at a constant deposition potential, applied to the corresponding aqueous electrolyte containing aniline and silica nanoparticles. The scanning electron microscopy (SEM) images showed the non-smooth and the porous surface structure of the prepared nanocomposite. The applicability of the new fiber coating was examined by headspace-solid phase microextraction (HS-SPME) of some environmentally important polycyclic aromatic hydrocarbons (PAHs), as model compounds, from aqueous samples....
An extended finite element method for hydraulic fracture propagation in deformable porous media with the cohesive crack model
, Article Finite Elements in Analysis and Design ; Volume 73 , 2013 , Pages 77-95 ; 0168874X (ISSN) ; Khoei, A. R ; Sharif University of Technology
Abstract
In this paper, a fully coupled numerical model is developed for the modeling of the hydraulic fracture propagation in porous media using the extended finite element method in conjunction with the cohesive crack model. The governing equations, which account for the coupling between various physical phenomena, are derived within the framework of the generalized Biot theory. The fluid flow within the fracture is modeled using the Darcy law, in which the fracture permeability is assumed according to the well-known cubic law. By taking the advantage of the cohesive crack model, the nonlinear fracture processes developing along the fracture process zone are simulated. The spatial discretization...
A new study in designing MTMDs in SDOF and MDOF systems based on the spectral analysis method
, Article Earthquake and Structures ; Volume 19, Issue 4 , 2020 , Pages 243-259 ; Shargh, F. H ; Rofooei, F. R ; Sharif University of Technology
Techno-Press
2020
Abstract
This study aims to optimize, design, and predict the MTMDs performance in SDOF systems using spectral analysis, and then apply their results to MDOF structures. Given the importance of spectral analysis in the design of new engineering structures, achieving a method for designing TMDs based on this theory can be of great importance for structural designers. In this study, several convenient combinations of MTMDs in an SDOF system are first considered to minimize the maximum displacement. For calculating the frequency ratios of dampers, an innovative technique is adopted in which the values of different modal responses obtained from the spectral analysis are approached together. This...
A new method to calculate efficiency of randomly-packed distillation columns and its comparison with the methods utilized in ASPEN Plus
, Article Fuel Processing Technology ; Volume 96 , 2012 , Pages 65-73 ; 03783820 (ISSN) ; Sadeghifar, A ; Sharif University of Technology
2012
Abstract
In this paper, a unique and applicable method was developed for calculation of efficiency (and mass and heat transfer coefficients) of randomly-packed distillation columns. This method has potential advantages; e.g., unlike all the available methods, it can calculate efficiency without using any empirical mass transfer and hydraulic correlations, and without the need to estimate the operational and hydraulic parameters of an operating column. It, therefore, will be free of errors and limitations of such empirical items and can be used for efficiency calculation of any random packing including new ones. Along with an analysis of the proposed method, the paper also presents a thorough analysis...
A new and applicable method to calculate mass and heat transfer coefficients and efficiency of industrial distillation columns containing structured packings
, Article Energy ; Volume 36, Issue 3 , 2011 , Pages 1415-1423 ; 03605442 (ISSN) ; Safe Kordi, A. A ; Sharif University of Technology
2011
Abstract
Most of the methods developed for efficiency estimation of distillation columns were based on the empirical mass transfer and hydraulic relations correlated to laboratory data. Therefore, these methods cannot estimate efficiency of industrial columns with sufficient accuracy. In this paper, a new and applicable method was developed for calculation of efficiency (and mass and heat transfer coefficients) of distillation columns containing structured packings. This method has potential advantages; e.g., it can calculate efficiency without using any empirical mass transfer and hydraulic correlations and models, and without the need to estimate the operational and hydraulic parameters of column....
An evolvable self-organizing neuro-fuzzy multilayered classifier with group method data handling and grammar-based bio-inspired supervisors for fault diagnosis of hydraulic systems
, Article International Journal of Intelligent Computing and Cybernetics ; Vol. 7, issue. 1 , 2014 , p. 38-78 ; Fathi, A ; Behzadipour, S ; Sharif University of Technology
Abstract
Purpose: The purpose of this paper is to apply a hybrid neuro-fuzzy paradigm called self-organizing neuro-fuzzy multilayered classifier (SONeFMUC) to classify the operating faults of a hydraulic system. The main motivation behind the use of SONeFMUC is to attest the capabilities of neuro-fuzzy classifier for handling the difficulties associated with fault diagnosis of hydraulic circuits. Design/methodology/approach: In the proposed methodology, first, the neuro-fuzzy nodes at each layer of the SONeFMUC are trained separately using two well-known bio-inspired algorithms, i.e. a semi deterministic method with random walks called co-variance matrix adaptation evolutionary strategy (CMA-ES) and...
An enriched-finite element technique for numerical simulation of hydro-fracture evolution in naturally-layered formations
, Article 6th ECCOMAS European Conference on Computational Mechanics: Solids, Structures and Coupled Problems, ECCM 2018 and 7th ECCOMAS European Conference on Computational Fluid Dynamics, ECFD 2018, 11 June 2018 through 15 June 2018 ; 2020 , Pages 1685-1696 ; Akhondzadeh, S. H ; Khoei, A. R ; Khalili, N ; Sharif University of Technology
International Centre for Numerical Methods in Engineering, CIMNE
2020
Abstract
In this paper, a computational model is developed for the simulation of hydro-fracture growth in naturally layered impervious media using the extended finite element method (X-FEM). The equilibrium equation of the bulk is solved in conjunction with the hydro-fracture inflow and continuity equations using the staggered Newton method. The hydro-fracture inflow is modeled by using the lubrication theory, where the permeability of the fracture is incorporated by taking advantage of the cubic law. The Eigen-function expansion method is utilized in order to develop enrichment functions suited for the asymptotic stress field in the vicinity of the singular points. An energy release rate-based...
An enriched–FEM technique for numerical simulation of interacting discontinuities in naturally fractured porous media
, Article Computer Methods in Applied Mechanics and Engineering ; Volume 331 , April , 2018 , Pages 197-231 ; 00457825 (ISSN) ; Vahab, M ; Hirmand, M ; Sharif University of Technology
Elsevier B.V
2018
Abstract
In this paper, an extended finite element method is presented for simulation of interaction between hydraulic fracturing and natural fractures in saturated porous media. The well-known u−p formulation is employed in order to obtain the fully coupled set of governing equations. Natural faults are modeled for both opening and closure modes where the fluid inflow and contact conditions are considered at the interface, respectively. The Darcy law is employed in conjunction with an aperture dependent permeability for the fracture channel to describe the interfacial inflow. The contact constraints of both the solid and fluid phases are imposed using the Penalty method. The Heaviside and modified...
An enriched FEM technique for modeling hydraulically driven cohesive fracture propagation in impermeable media with frictional natural faults: Numerical and experimental investigations
, Article International Journal for Numerical Methods in Engineering ; Volume 104, Issue 6 , 2015 , Pages 439-468 ; 00295981 (ISSN) ; Hirmand, M ; Vahab, M ; Bazargan, M ; Sharif University of Technology
John Wiley and Sons Ltd
2015
Abstract
In this paper, an enriched finite element technique is presented to simulate the mechanism of interaction between the hydraulic fracturing and frictional natural fault in impermeable media. The technique allows modeling the discontinuities independent of the finite element mesh by introducing additional DOFs. The coupled equilibrium and flow continuity equations are solved using a staggered Newton solution strategy, and an algorithm is proposed on the basis of fixed-point iteration concept to impose the flow condition at the hydro-fracture mouth. The cohesive crack model is employed to introduce the nonlinear fracturing process occurring ahead of the hydro-fracture tip. Frictional contact is...
An applicable method for efficiency estimation of operating tray distillation columns and its comparison with the methods utilized in HYSYS and Aspen Plus
, Article Heat and Mass Transfer/Waerme- und Stoffuebertragung ; Volume 51, Issue 10 , October , 2015 , Pages 1393-1402 ; 09477411 (ISSN) ; Sharif University of Technology
Springer Verlag
2015
Abstract
Developing general methods that rely on column data for the efficiency estimation of operating (existing) distillation columns has been overlooked in the literature. Most of the available methods are based on empirical mass transfer and hydraulic relations correlated to laboratory data. Therefore, these methods may not be sufficiently accurate when applied to industrial columns. In this paper, an applicable and accurate method was developed for the efficiency estimation of distillation columns filled with trays. This method can calculate efficiency as well as mass and heat transfer coefficients without using any empirical mass transfer or hydraulic correlations and without the need to...
An ant-based rate allocation algorithm for media streaming in peer to peer networks: Extension to multiple sessions and dynamic networks
, Article Journal of Network and Computer Applications ; Volume 34, Issue 1 , 2011 , Pages 327-340 ; 10848045 (ISSN) ; Salavati, A. H ; Pakravan, M. R ; Sharif University of Technology
Abstract
In this paper, we introduce a novel algorithm for rate allocation in media streaming P2P networks where multimedia contents are distributed among network members and streamed toward any requesting peer. The proposed algorithm is based on ant-colony optimization. It is capable of handling network dynamism, which is an inherent property of unstructured P2P networks. Another advantage of our algorithm is its ability to get over uncertainties in network state information, particularly the rate of supplying peers that could happen due to lack of accurate measurements. In addition, the suggested method does not rely on any information about the topology of the network. We have investigated both...
Analyzing and predicting permeability coefficient of roller-compacted concrete (RCC)
, Article Journal of Testing and Evaluation ; Volume 49, Issue 3 , 2019 ; 00903973 (ISSN) ; Toufigh, V ; Ghaemian, M ; Sharif University of Technology
ASTM International
2019
Abstract
The permeability of roller-compacted concrete (RCC) substantially affects its functionality and safety. This study investigates the effect of mix design parameters on the performance of RCC. For this purpose, approximately 500 laboratory specimens were prepared and tested. A formula and an artificial neural network (ANN) were proposed to predict the permeability coefficient of RCC by considering the main parameters, which were then verified independently using new specimens. Furthermore, the experimental data were analyzed by the Taguchi method and analysis of variance (ANOVA) to evaluate the level of parameter contribution. Based on the results, the permeability coefficient was highly...
Analytical study of fluid flow modeling by diffusivity equation including the quadratic pressure gradient term
, Article Computers and Geotechnics ; Volume 89 , 2017 , Pages 1-8 ; 0266352X (ISSN) ; Izadmehr, M ; Karimi, M ; Sharifi, M ; Kazemi, A ; Sharif University of Technology
Abstract
Diffusivity equation which can provide us with the pressure distribution, is a Partial Differential Equation (PDE) describing fluid flow in porous media. The quadratic pressure gradient term in the diffusivity equation is nearly neglected in hydrology and petroleum engineering problems such as well test analysis. When a compressible liquid is injected into a well at high pressure gradient or when the reservoir possess a small permeability value, the effect of ignoring this term increases. In such cases, neglecting this parameter can result in high errors. Previous models basically focused on numerical and semi-analytical methods for semi-infinite domain. To the best of our knowledge, no...