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Dynamic behavior of worn wheels in a track containing several sharp curves based on field data measurements and simulation
, Article Scientia Iranica ; Volume 26, Issue 5 B , 2019 , Pages 2839-2853 ; 10263098 (ISSN) ; Farrahi, G. H ; Sohrabpour, S ; Sharif University of Technology
Sharif University of Technology
2019
Abstract
A study of the wheel and rail wear phenomenon can provide a chance for the optimal use of wheel profile, which results in cost efficiency, dynamic stability, travel comfort, and safety to prevent the derailment, especially in curves. In this paper, the experimental data are recorded based on the field measurements for worn wheels of a passenger wagon in the "Southern line" of Iran's railway system and are combined with the dynamic simulations to study the effects of severe wheel flange wear on the dynamics of wagon. The results show that the amount of wheel wear (especially the wheel flange) directly impacts the dynamic behavior of the wagon in curves. In addition, based on the history of...
A bridge between dual porosity and multiscale models of heterogeneous deformable porous media
, Article International Journal for Numerical and Analytical Methods in Geomechanics ; Volume 43, Issue 1 , 2019 , Pages 212-238 ; 03639061 (ISSN) ; Khoei, A. R ; Sharif University of Technology
John Wiley and Sons Ltd
2019
Abstract
In this paper, a multiscale homogenization approach is developed for fully coupled saturated porous media to represent the idealized sugar cube model, which is generally employed in fractured porous media on the basis of dual porosity models. In this manner, an extended version of the Hill-Mandel theory that incorporates the microdynamic effects into the multiscale analysis is presented, and the concept of the deformable dual porosity model is demonstrated. Numerical simulations are performed employing the multiscale analysis and dual porosity model, and the results are compared with the direct numerical simulation through 2 numerical examples. Finally, a combined multiscale-dual porosity...
Simulation of blood particle separation in a trapezoidal microfluidic device by acoustic force
, Article IEEE Transactions on Electron Devices ; Volume 66, Issue 3 , 2019 , Pages 1495-1503 ; 00189383 (ISSN) ; Yazdan Parast, F ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2019
Abstract
Nowadays, the importance of the blood particles separation is undeniable in medical fields and there are different sorts of separation methods accordingly. Acoustic cell separation is chosen in this paper. Also, numerical methods have been used to study the effect of geometrical factors on the separation of the particles before spending time and expenses in a trial and error manner experimentally. We have implemented a plenary finite-element-based simulation of separatingblood particles such as white blood cells and platelets in an acoustic field using standing surface acoustic waves. In this paper, unlike previous works in which the channel is rectangular; the channel is trapezoidal in...
Freshwater and cooling production via integration of an ethane ejector expander transcritical refrigeration cycle and a humidification-dehumidification unit
, Article Desalination ; Volume 477 , 2020 ; Vajdi, M ; Rostamzadeh, H ; Sharif University of Technology
Elsevier B.V
2020
Abstract
Despite the fact that humidification-dehumidification (HDH) desalination systems can be driven by various renewable or waste heat energies, many of the available renewable technologies are expensive in some parts of the globe. Hence, proposing and developing high-efficient mechanical-based HDH units can be an encouraging alternative which is more highlighted in recent investigations. In pursuance of this objective, three innovative mechanical-driven HDH units are simulated and the results are compared with each other. The simulated hybrid desalination system consists of a HDH unit and an ethane ejector expander transcritical refrigeration cycle (ethane-EETRC). The simulated hybrid systems...
A numerical study on utilizing horizontal flat-panel ground heat exchangers in ground-coupled heat pumps
, Article Renewable Energy ; Volume 147 , March , 2020 , Pages 996-1010 ; Amadeh, A ; Hakkaki Fard, A ; Sharif University of Technology
Elsevier Ltd
2020
Abstract
Horizontal ground heat exchangers (GHEs) have a lower cost in comparison to vertical ones; however, they require more land area. For the sake of reducing the required land area for horizontal GHEs, flat-panel GHEs have been recently introduced. In this piece of research, a 3-D numerical model has been developed to predict the thermal performance of flat-panel GHEs. In this study, at first, the thermal performance of a flat-panel GHE has been compared with that of linear horizontal ones. The results demonstrate that the flat-panel GHE has a better thermal performance of about 27% in comparison to an arrangement of linear GHEs with a value of 0.5 m for pipe spacing. In the second part of this...
Numerical simulation of proppant transport and tip screen-out in hydraulic fracturing with the extended finite element method
, Article International Journal of Rock Mechanics and Mining Sciences ; Volume 128 , 2020 ; Khoei, A. R ; Sharif University of Technology
Elsevier Ltd
2020
Abstract
In this paper, a numerical model is developed based on the X-FEM technique to simulate the proppant transport and tip screen-out in hydraulic fracturing. The governing equations are based on the momentum balance and mass conservation of the fluid. The hydro-mechanical coupling between the fracture and surrounding porous medium is fulfilled through the weak form of the governing equations. The fluid inflow within the fracture is modeled using the one-dimensional mass conservation of the injected slurry and proppant along the fracture, in which the viscosity of the slurry is dependent on the proppant concentration. The transition from the Poiseuille to Darcy flow regime is incorporated into...
Numerical modeling of density-driven solute transport in fractured porous media with the extended finite element method
, Article Advances in Water Resources ; Volume 136 , 2020 ; Bajalan, Z ; Khoei, A. R ; Sharif University of Technology
Elsevier Ltd
2020
Abstract
In this paper, a numerical model is developed based on the X-FEM technique to simulate the transport of dense solute in a single fluid phase through the fractured porous media. The governing equation is based on the mass conservation law which is applied to the fluid phase and the solute in both matrix and fracture domain. The integral governing equations of the mass exchange between the fracture and the surrounding matrix is derived. The extended finite element method (X-FEM) is applied by employing appropriate enrichment functions to model the fractured porous domain. The superiority of the X-FEM is that the FE mesh is not necessary to be conformed to the fracture geometry, so the regular...
Rigid-bar loading on pregnant uterus and development of pregnant abdominal response corridor based on finite element biomechanical model
, Article International Journal for Numerical Methods in Biomedical Engineering ; Volume 36, Issue 1 , January , 2020 ; Ahmadian, M. T ; Mohammadi, H ; Sharif University of Technology
Wiley-Blackwell
2020
Abstract
During pregnancy, traumas can threaten maternal and fetal health. Various trauma effects on a pregnant uterus are little investigated. In the present study, a finite element model of a uterus along with a fetus, placenta, amniotic fluid, and two most effective ligament sets is developed. This model allows numerical evaluation of various loading on a pregnant uterus. The model geometry is developed based on CT-scan data and validated using anthropometric data. Applying Ogden hyper-elastic theory, material properties of uterine wall and placenta are developed. After simulating the “rigid-bar” abdominal loading, the impact force and abdominal penetration are investigated. Findings are compared...
A novel linear solver for simulating highly heterogeneous black oil reservoirs
, Article Journal of Petroleum Science and Engineering ; Volume 194 , November , 2020 ; Eslahi, R ; Bakhtiari, M ; Alizadeh, A ; Madani, M ; Zeinali, M ; Rajabi, H ; Sharifi, E ; Mortezazadeh, E ; Mahdavifar, Y ; Sharif University of Technology
Elsevier B.V
2020
Abstract
A great deal of computational power and time is necessary for the simulation of highly heterogeneous fractured reservoirs with complicated geometry. Simulating such largescale complex reservoirs with both minimum time and maximum accuracy has consistently remained a topic of concern to reservoir simulation engineers worldwide. The currently used linear solvers in well-known commercial simulators that utilize classical methods such as Nested Factorization (NF) and Incomplete LU Factorization (ILU) as their preconditioners, all suffer from severe convergence problems in models with high heterogeneity and/or large number of non-neighbor connections. To overcome such problems, a novel Adaptive...
Incorporation of strong motion duration in incremental-based seismic assessments
, Article Engineering Structures ; Volume 223, Issue 15 , November , 2020 ; Harati, M ; Darzi, A ; Estekanchi, H. E ; Sharif University of Technology
Elsevier Ltd
2020
Abstract
This study proposes a new approach to incorporate motion duration in incremental dynamic assessments. In the proposed methodology, at each intensity level, a simulation-based approach which is verified with actual data is employed to determine the median duration and the median acceleration spectra of ground motions expected to occur at the site. Afterward, at each intensity level, artificial or spectrally matched motions are produced based on the median acceleration spectra and the median duration, indicating that different intensity levels are directly covered by the generated artificial or adjusted motions rather than just scaling up and down a set of recorded ground motions. In the...
Does the short-term boost of renewable energies guarantee their stable long-term growth? Assessment of the dynamics of feed-in tariff policy
, Article Renewable Energy ; Volume 159 , October , 2020 , Pages 1252-1268 ; Hamed Shakouri, G ; Mashayekhi, A. N ; Kazemi, A ; Sharif University of Technology
Elsevier Ltd
2020
Abstract
Feed-in tariff (FiT) is one of the most efficient ways that many governments throughout the world use to stimulate investment in renewable energies (REs) technology. For governments, financial management of the policy could be challenging as it needs a considerable amount of budget to support RE producers during the long remuneration period. In this paper, it has been illuminated that the early growth of REs capacity could be a temporary boost. And the socio-economic structure of the system will backlash the policy if some social mechanisms are not considered. Social tolerance for paying REs tax and potential investors’ trust emanated from budget-related mechanisms -which have rarely been...
Studying effect of entrainment on dynamics of debris flows using numerical simulation
, Article Computers and Geosciences ; Volume 134 , 2020 ; Manzari, M. T ; Sharif University of Technology
Elsevier Ltd
2020
Abstract
This paper studies entrainment phenomenon in debris flows using full flow (non-depth-averaged) equations and an Incompressible Smoothed Particle Hydrodynamics (ISPH) method. A viscoplastic constitutive relationship is adopted for both the overlying fluid and bed material. Collapse of a two-dimensional dry granular column on a horizontal bed consisting of entrainable dry granular material is considered as a benchmark problem. The adopted ISPH method for simulation of collapse over rigid and entrainable beds is validated using available numerical and experimental data. To quantify the effects of entrainment on dynamics of flow, the initial aspect ratio of granular column (a) is varied and the...
Smooth switching in power control of wind turbines using a combination strategy of hysteresis and modified middle regions
, Article Sustainable Energy Technologies and Assessments ; Volume 37 , 2020 ; Moradi, H ; Sharif University of Technology
Elsevier Ltd
2020
Abstract
This paper presents a new method for protecting the variable speed wind turbines in switching between different regions. With the objective of power maximization, the controller is applied in all regions. Since usually different methods and algorithms are used in different regions for controlling the wind turbines, smooth transition between these controllers is necessary for the safety and protection of turbine parts and structure. A two degree of freedom mechanical model is used and the simulations are performed and verified by FAST. The turbine is controlled by a rotor angular speed controller in the second region and an inverse dynamic pitch controller in the third region. The transient...
Computer modeling of the operating room ventilation performance in connection with surgical site infection
, Article Scientia Iranica ; Volume 27, Issue 2 , 2020 , Pages 704-714 ; Saidi, M. H ; Ahmadi, G ; Sharif University of Technology
Sharif University of Technology
2020
Abstract
The primary source of surgical site infection is the deposition of flakes released from the exposed skin of surgical staff or the patient on the exposed surgical wound. In this study, a computational model for simulating air ow and thermal conditions in an operating room is developed, and transport and deposition of particulate contaminants near the wound are analyzed. The results show the formation of a thermal plume over the wound tissue, which is typically at a higher temperature than the surrounding. The thermal plume protects the wound from the deposition of contaminants. In addition, the computational model predicts an optimum value for the inlet air velocity that is mainly maintaining...
A numerical study on a photovoltaic thermal system integrated with a thermoelectric generator module
, Article Renewable Energy ; Volume 153 , 2020 , Pages 1261-1271 ; Parcheforosh, A ; Hakkaki Fard, A ; Amadeh, A ; Sharif University of Technology
Elsevier Ltd
2020
Abstract
In this work, a three-dimensional numerical model is developed to investigate the performance of a photovoltaic thermal system integrated with a thermoelectric generator module (PVT/TE). Furthermore, the effects of various operating parameters such as solar radiation, coolant mass flow rate, and inlet and ambient temperatures on the performance of both the PVT and PVT/TE systems are investigated and compared. Based on the obtained results, the electrical efficiency of the PVT/TE system, when exposed to solar radiation of 600 and 1000 W/m2, is 6.23% and 10.41% higher than that of the PVT system, respectively. Besides, the electrical efficiency of the PVT and PVT/TE by increasing the inlet...
Investigation of a Novel Microfluidic Device for Label-Free Ferrohydrodynamic Cell Separation on a Rotating Disk
, Article IEEE Transactions on Biomedical Engineering ; Volume 67, Issue 2 , 2020 , Pages 372-378 ; Besanjideh, M ; Sharif University of Technology
IEEE Computer Society
2020
Abstract
Negative magnetophoresis is a novel and attractive method for continuous microparticle sorting inside a magnetic medium. In this method, diamagnetic particles are sorted based on their sizes using magnetic buoyancy force and without any labeling process. Although this method provides some attractive features, such as low-cost fabrication and ease of operation, there are some obstacles that adversely affect its performance, especially for biological applications. Most types of magnetic media, such as ferrofluids, are not biocompatible, and the time-consuming process of sample preparation can be threatening to the viability of the cells within the sample. Furthermore, in this method, both the...
A hepatocellular carcinoma–bone metastasis-on-a-chip model for studying thymoquinone-loaded anticancer nanoparticles
, Article Bio-Design and Manufacturing ; Volume 3, Issue 3 , 2020 , Pages 189-202 ; Yesil Celiktas, O ; Kazan, A ; Maharjan, S ; Saghazadeh, S ; Firoozbakhsh, K ; Firoozabadi, B ; Zhang, Y. S ; Sharif University of Technology
Springer
2020
Abstract
We report the development of a metastasis-on-a-chip platform to model and track hepatocellular carcinoma (HCC)–bone metastasis and to analyze the inhibitory effect of an herb-based compound, thymoquinone (TQ), in hindering the migration of liver cancer cells into the bone compartment. The bioreactor consisted of two chambers, one accommodating encapsulated HepG2 cells and one bone-mimetic niche containing hydroxyapatite (HAp). Above these chambers, a microporous membrane was placed to resemble the vascular barrier, where medium was circulated over the membrane. It was observed that the liver cancer cells proliferated inside the tumor microtissue and disseminated from the HCC chamber to the...
Impact of trim on added resistance of KRISO container ship (KCS) in head waves: An experimental and numerical study
, Article Ocean Engineering ; Volume 211 , 2020 ; Khorasanchi, M ; Day, S ; Turan, O ; Sharif University of Technology
Elsevier Ltd
2020
Abstract
In this study, added resistance and motion responses of KRISO Container Ship (KCS) were evaluated experimentally and numerically in six different trim angles. A series of towing tank experiments were performed for six different trim angles at design speed in calm water and regular head waves. The ship motions and added resistance were measured for several wavelength conditions considering short and long wave ranges with wave steepness of 1/60. Next, computations of the towed model in calm water and waves were performed using Unsteady Reynolds-Averaged Navier-Stokes (URANS) CFD and 3-D potential methods. Effects of trim angles on added resistance were analysed and results concerning the...
Investigation of rock salt layer creep and its effects on casing collapse
, Article International Journal of Mining Science and Technology ; Volume 30, Issue 3 , 2020 , Pages 357-365 ; Pak, A ; Shad, S ; Mehrgini, B ; Razifar, M ; Sharif University of Technology
China University of Mining and Technology
2020
Abstract
Casing collapse is one of the costly incidents in the oil industry. In the oil fields of southwest Iran, most casing collapses have occurred in Gachsaran formation, and the halite rock salt layer in this formation may be the main cause for these incidents because of its peculiar creep behavior. In this research, triaxial creep experiments have been conducted on Gachsaran salt samples under various temperatures and differential stresses. The main purpose was to determine the creep characteristics of Gachsaran rock salt, and to examine the role of creep in several casing collapses that occurred in this formation. Results indicated that the halite rock salt of Gachsaran formation basically...
Phase-field simulation of weld solidification microstructure in an Al-Cu alloy
, Article Modelling and Simulation in Materials Science and Engineering ; Volume 16, Issue 6 , 11 August , 2008 ; 09650393 (ISSN) ; Do Quang, M ; Serajzadeh, S ; Kokabi, A. H ; Amberg, G ; Sharif University of Technology
2008
Abstract
Since the mechanical properties and the integrity of the weld metal depend on the solidification behaviour and the resulting microstructural characteristics, understanding weld pool solidification is of importance to engineers and scientists. Thermal and fluid flow conditions affect the weld pool geometry and solidification parameters. During solidification of the weld pool, a columnar grain structure develops in the weld metal. Prediction of the formation of the microstructure during welding may be an important and supporting factor for technology optimization. Nowadays, increasing computing power allows direct simulations of the dendritic and cell morphology of columnar grains in the...