Search for: three-dimensional-model
Total 112 records
Three-dimensional data transfer operators in plasticity using SPR technique with C0, C1 and C2 continuity, Article Scientia Iranica ; Volume 15, Issue 5 , 2008 , Pages 554-567 ; 10263098 (ISSN) ; Gharehbaghi, S. A ; Sharif University of Technology
Sharif University of Technology 2008
In this paper, the data transfer operators are developed in three-dimensional elasto-plasticity using the Superconvergent Patch Recovery (SPR) method. The transfer operators are defined for mapping of the state and internal variables between different meshes. The internal variables are transferred from Gauss points of old mesh to the nodal points. The variables are then transferred from the nodal points of old mesh to the nodal points of new mesh. Finally, the values are computed at the Gauss points of new mesh using their values at the nodal points. Aspects of the transfer operators are presented in a three-dimensional superconvergent path recovery technique, based on C0, C1 and C2...
Multi-channel electrocardiogram denoising using a Bayesian filtering framework, Article 2006 Computers in Cardiology, CIC, Valencia, 17 September 2006 through 20 September 2006 ; Volume 33 , 2006 , Pages 185-188 ; 02766574 (ISSN); 1424425328 (ISBN); 9781424425327 (ISBN) ; Shamsollahi, M. B ; Jutten, C ; Sharif University of Technology
In some recent works, model-based filtering approaches have been proved as effective methods for extracting ECG signals from single channel noisy recordings. The previously developed methods, use a highly realistic nonlinear ECG model for the construction of Bayesian filters. In this work, a multi-channel extension of the previous approach is developed, by using a three dimensional model of the cardiac dipole vector. The results have considerable improvement compared with the single channel approach. The method is hence believed to be applicable to low SNR multi-channel recordings
Three-dimensional simulation of urine concentrating mechanism in a functional unit of rat outer medulla. I. Model structure and base case results, Article Mathematical Biosciences ; Vol. 258 , 2014 , pp. 44-56 ; ISSN: 00255564 ; Saidi, M. S ; Saadatmand, M ; Banazadeh, M. H ; Firoozabadi, B ; Sharif University of Technology
The urine formation and excretion system have long been of interest for mathematicians and physiologists to elucidate the obscurities within the process happens in renal tissue. In this study, a novel three-dimensional approach is utilized for modeling the urine concentrating mechanism in rat renal outer medulla which is essentially focused on demonstrating the significance of tubule's architecture revealed in anatomic studies and physiological literature. Since nephrons and vasculatures work interdependently through a highly structured arrangement in outer medulla which is dominated by vascular bundles, a detailed functional unit is proposed based on this specific configuration....
Numerical investigation and parametric analysis of a photovoltaic thermal system integrated with phase change material, Article Applied Energy ; Volume 238 , 2019 , Pages 734-746 ; 03062619 (ISSN) ; Salari, A ; Hakkaki Fard, A ; Ma, T ; Sharif University of Technology
Elsevier Ltd 2019
In this paper, a comprehensive three-dimensional model of photovoltaic thermal system integrated with phase change material (PVT/PCM) is developed and simulated. The effect of some key parameters using parametric analysis on performance of PVT/PCM system with water as working fluid is investigated. Parameters considered in this study include the properties of PCM (i.e. melting temperature, enthalpy of fusion and thermal conductivity), solar radiation and mass flow rate. The parametric analysis ranges are selected according to the properties of the most of available PCMs on the market, which shows the practical application of the numerical research. Furthermore, a three-dimensional model of...
Prediction of particle deposition in the respiratory track using 3D-1D modeling, Article Scientia Iranica ; Volume 19, Issue 6 , December , 2012 , Pages 1479-1486 ; 10263098 (ISSN) ; Dastanpour, R ; Saidi, M. S ; Pishevar, A. R ; Sharif University of Technology
Airflow simulation of the whole respiratory system is still unfeasible due to the geometrical complexity of the lung airways and the diversity of the length scales involved in the problem. Even the new CT imaging system is not capable of providing accurate 3D geometries for smaller tubes, and a complete 3D simulation is impeded by the limited computational resources available. The aim of this study is to develop a fully coupled 3D-1D model to make accurate prediction of airflow and particle deposition in the whole respiratory track, with reasonable computational cost and efficiency. In the new proposed method, the respiratory tree is divided into three parts to be dealt with using different...
Evaluation of Endurance Time Method in Nonlinear Dynamic Analysis of Unreinforced Brick Masonry Buildings, M.Sc. Thesis Sharif University of Technology ; Esmaeil Pourestekanchi, Homayoon
The existing statistical studies implies that in Iran like most of developing countries, the great percent of houses are traditional. Statistics of the most disastrous current quakes also show damages caused by masonry structures in developing countries. The main problem of brick and masonry structures especially the unreinforced one is their weak performance against quake. Different methods are use to analyse the seismic performance of this structures. The modern endurance time method is a kind of time history analysis using standard increasing accelerograms which examines different parameters of structure behavior during excitation actions. In this project we analyse these structures using...
Flow-Field Modeling and Performance Prediction of Axial-Flow Compressors using Streamline Curvature Method, M.Sc. Thesis Sharif University of Technology ; Ghofrani, Mohammad Bagher ; Nouri Borujerdi, Ali
Compressors are one of the most important components of gas turbines and turbomachinery processes. Thus some precise and quick tools are needed for design and analysis purposes. Despite of vast development of Computational Fluid Dynamics (CFD) tools, Through-Flow Streamline Curvature Methods (SCM) has retained their position. 2D and quasi-3D forms of SCM in combination with CFD results nowadays make more than 80% of turbomachinery design process of axial and radial compressors and turbines. In this thesis, the basics of developing a tool for axial-flow compressor analysis are introduced. As will be seen, this analysis tool can be used for design purposes too. The method that is chosen for...
Study of the Effect of Central Beam Column (CBC) Structure on Sequential Excavation of Large Span Underground Station, M.Sc. Thesis Sharif University of Technology ; Ahmadi, Mohammad Mehdi
Effect of utilizing Central Beam Column (CBC) structure on shallow, large span underground spaces excavation is studied. The CBC method focuses on increasing the overall rigidity of tunnel supporting system prior to full face excavation, in which central drift excavation is limited to the dimensions of the central beam and column to reduce disturbances. Constructing the central beam and column structure, the excavation is completed with NATM excavation method in a symmetric manner about centerline. In CBC method on each side of the centerline there is an arch structure composed of the initial lining resting on roof beam on top and bottom beam at the invert. The roof and bottom beams take the...
3D Modeling South Three-Way Station1 of Mehrabad Airport and Tunnels Connected to the Station and Connecting Tunnel with Line4 of Metro Tehran, M.Sc. Thesis Sharif University of Technology ; Sadaghiani, Mohammad Hossein
Recently, due to the major need of the development of underground spaces in dense urban areas, excavating tunnels near to the earth surface is arising. Therefore, there is a possibility that the new tunnels drill and construct in the vicinity or along the available tunnels. Thus, the interaction mechanism of this tunnels on each other and on land subsidence should be taken into consideration. In this research using ABAQUS finite element analysis software the interactions of the cross road subway station of Bimeh-Mehrabad airport in the line 4 of the Tehran city subway lines which is excavated using multistage drilling method is investigated. This model includes Eastern, Western and a...
Analysis of Stability and Ground Settlement in Construction Stages of Underground Exchange Station between Line 3 and 4 At Mashhad Subway, M.Sc. Thesis Sharif University of Technology ; Sadaghiani, Mohammad Hossein
Deformation and Settlement of the ground surface and stability of large underground space is the main concern in the excavation under urban area. In order to control settlement and increase stability, it is necessary to use pre-Supporting system prior to excavation. Concrete Arc Pre-supporting System (CAPS) is one of the most useful pre-supporting methods which is used in exchange station of line 3 and 4 of Mashhad subway. Line 3 and 4 are parallel in Shohada square and the groundwater level is above the whole station structure. To analyze deformation of the ground due to excavation stages, the station was modeled in 2D and 3D by Abaqus. In this study, to estimate ground Deformation, we need...
Evaluation the Surface Settlement and Interaction Between Tunnelinline2 and Metro Station Inline1 of Mashhad Metro at Intersection Using 3-D Numerical Modeling, M.Sc. Thesis Sharif University of Technology ; Sadaghiani, Mohammad Hossein
In this study, the interaction of tunneling of line 2 of Mashhad metro and existing metro station (Shariati station) in line 1 has been investigated. To produce the stress and displacement which is caused by excavation of station, the process of station excavation has been modeled by method of cut and cover.This method is the common method for station construction at Shallow depth and is used in several cases in line 1 of Mashhad metro. The piled-raft system is used in foundation of central part of the station to reduce the settlements and the effects of interactions between the station and new tunnel. The new tunnel under the station is surrounded by two rows of lateral piles with distance...
The Behavior of Supporting Structures with Pretension Anchors by Geotechnical Softwares, M.Sc. Thesis Sharif University of Technology ; Ahmadi, Mohammad Mehdi
In recent years, due to urban expansion and population growth, number of floors and excavations depth has increased. Stabilization of excavations is one of the most important issues in geotechnical engineering. Today, one of the most widely used methods that is used in deep excavations is brace soil by steels and pretension them. In this thesis tries to evaluate static behavior of flexible supporting structures with pretension anchors by using PLAXIS2D, FLAC3D and GEOSTUDIO softwares. The objective of this modeling is better understanding the static behavior of walls, comparing the two and three dimensional modeling and the effect of corners of excavation on deformation. The results shows...
Three Dimensional Computational Modeling of Multiphase Flow in Proton Exchange Membrane Fuel Cells, M.Sc. Thesis Sharif University of Technology ; Mazaheri, Karim ; Roshandel, Ramin
Proton exchange membrane (PEM) fuel cell performance is directly related to the flow channel design on bipolar plates. Power gains can be found by varying the type, size, or arrangement of channels. It has been understood that the flow field design has deterministic role on mass transport and water management in a PEM Fuel cell. This study concentrates on improvements in the fuel cell performance through optimization of channel dimensions and configurations. A 3D, multi-component numerical model of flow distribution based on the Navier-Stokes equations using individual computer code is presented. The simulation results showed excellent agreement with the experimental results in previous...
Investigation of Excitation-contraction behavior in Skeletal Muscle by Means of Chemomechanical Modeling, Ph.D. Dissertation Sharif University of Technology ; Zohoor, Hassan ; Firoozbakhsh, Keikhosrow
Numerous studies have shown a direct relationship between skeletal muscle active force and intracellular calcium ion concentrations; In fact, no matter how the muscle is stimulated (neurological, electrical, chemical, and mechanical stimuli), the main cause of muscle activation and consequently force generation is calcium ions.According to this scientific finding, the purpose of this study is to present a new chemo-mechanical multiscale model of skeletal muscle based on the fundamental principles of continuum thermodynamics. In this model, unlike other similar studies, muscle active force is not considered as the conventional multiplication of isometric force in a set of corrective...
Assessment of 2DH and pseudo-3D modelling platforms in a large saline aquatic system: Lake Urmia, Iran, Article Hydrological Processes ; Vol. 28, Issue. 18 , 2014 , pp. 49534970 ; ISSN: 10991085 ; Tofighi, M. A ; Bakhtiari, A ; Sharif University of Technology
The main objective of this paper is to provide comparative quantitative examinations on the capabilities of two-dimensional horizontal and pseudo-three-dimensional (3D) modelling approaches for simulating spatial and temporal variability of the flow and salinity in Lake Urmia, Iran. The water quality in the lake has been an environmentally important subject partly because this shallow hypersaline aquatic ecosystem is considered to be one of the largest natural habitats of a unique multicellular organism, Artemia urmiana. This brine shrimp is the major food source for many of the protected and rare shorebirds that visit the lake. A.urmiana can grow and survive in certain ranges of salinity,...
A new correlation on the MEXICO experiment using a 3D enhanced blade element momentum technique, Article International Journal of Sustainable Energy ; Vol. 33, issue. 2 , 2014 , pp. 448-460 ; ISSN: 14786451 ; Jafari, A ; Schaffarczyk, A. P ; Keyhani, A ; Mahmoudi, J ; Sharif University of Technology
The blade element momentum (BEM) theory is based on the actuator disc (AD) model, which is probably the oldest analytical tool for analysing rotor performance. The BEM codes have very short processing times and high reliability. The problems of the analytical codes are well known to the researchers: the impossibility of describing inside the one-dimensional code the three-dimensional (3D) radial flows along the span-wise direction. In this work, the authors show how the 3D centrifugal pumping affects the BEM calculations of a wind turbine rotor. Actually to ascertain the accuracy of the analytical codes, the results are compared with rotor performance, blade loads and particle image...
A study on thermal responses, microstructural issues, and natural aging in gas tungsten arc welding of AA2024-T4, Article Proceedings of the Institution of Mechanical Engineers, Part B: Journal of Engineering Manufacture ; Vol. 228, issue. 3 , 2014 , p. 413-421 ; Serajzadeh, S ; Kokabi, A. H ; Sharif University of Technology
In this study, a three-dimensional model has been utilized for predicting thermal responses during tungsten arc welding of AA2024-T4 plates in which double ellipsoidal heat source model was employed to consider the moving torch in the model. Furthermore, tensile and hardness tests and microstructural evaluations have been carried out to investigate the mechanical properties and the microstructures within the welded metal. The results show that there is a region inside the heat-affected zone where hardness increases while in some parts of this region having temperatures higher than 250 C the hardness decreases significantly. Furthermore, natural aging occurs after welding; however, its...
Unsupported advance length in tunnels constructed using New Austrian Tunnelling Method and ground surface settlement, Article International Journal for Numerical and Analytical Methods in Geomechanics ; Volume 37, Issue 14 , 2013 , Pages 2170-2185 ; 03639061 (ISSN) ; Ahmadi, M. M ; Hajjar, M ; Kashighandi, A ; Sharif University of Technology
Tunnels constructed using New Austrian Tunnelling Method (NATM) are always based on certain round (unsupported) advance lengths, after which, the temporary lining is placed. The settlement of the ground surface resulting from such construction is of high significance in design and practice. The existing data in this respect, however, is scarce. It is the aim of this paper to propose a semi-analytical procedure based on three-dimensional finite element analyses to predict the maximum surface settlement of the ground in NATM tunnels under different combinations of tunnel diameter, overburden depth, round length and soil and lining properties. The comparison of the results with three case...
Field scale characterization of geological formations using percolation theory, Article Transport in Porous Media ; Volume 92, Issue 2 , 2012 , Pages 357-372 ; 01693913 (ISSN) ; Masihi, M ; Shojaei, A ; Pishvaie, M ; King, P. R ; Sharif University of Technology
The connectivity of high conductivity pathways in geological formations depend on the spatial distribution of geological heterogeneities that may appear on various length scales. Appropriate modeling of this is crucial within in hydrology and petroleum systems. The approach taken in this study is to use percolation theory to quantify the connectivity, hydraulic conductivity, and breakthrough time behavior between an injector and a producer within such systems. In particular, a three-dimensional overlapping sandbody model is considered which assumes that the geological formation can be split into either conductive flow units (i. e., good sands) or non-conductive units (i. e., poor sands). The...
Proposal of a new design for valveless micropumps, Article Scientia Iranica ; Volume 18, Issue 6 , December , 2011 , Pages 1261-1266 ; 10263098 (ISSN) ; Movahhedy, M. R ; Assempour, A ; Sharif University of Technology
A new design for a valveless micropumping device has been proposed that integrates two existing pumping technologies, namely, the wall induced traveling wave and the obstacle-type valveless micropump. The liquid in the microchannel is transported by generating a traveling wave on the channel, while the placing of two asymmetric trapezoid obstacles, along the centerline of the channel inlet and outlet, leads to a significant (up to seven times) increase of the net flow rate of the device. The effectiveness of this innovative design has been proved through a verified three-dimensional finite element model. FluidStructure Interaction (FSI) analysis is performed in the framework of an Arbitrary...