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porosity
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Using the laser irradiation to improve the rate of production of Iran South West formation
, Article Society of Petroleum Engineers - Kuwait International Petroleum Conference and Exhibition 2012, KIPCE 2012: People and Innovative Technologies to Unleash Challenging Hydrocarbon Resources ; Volume 1 , 2012 , Pages 141-147 ; 9781622769766 (ISBN) ; Habibpour, M ; Jalalyfar, H ; Geranmayehrad, A ; Sharif University of Technology
2012
Abstract
Whole level of the erosion and the resistance of rocks which were composed closured have been studied, besides, the impact of temperature and laser irradiation for more investigation about this issue has been involved before all. This subject more reveals the matter which laser absorption on the laboratory scale using laser to what extent can cause the augment of the relative permeability and secondary porosity of reservoir rock, that of the vertical and horizontal useful connectivity and eventually that of the positive transferability. This research has been carried out in the form of case study on one of Iranian south west formations in north east of Behbahan city in Iran, either the rate...
A steady-state saturation model to determine the subsurface travel time (STT) in complex hillslopes
, Article Hydrology and Earth System Sciences ; Volume 14, Issue 6 , Jun , 2010 , Pages 891-900 ; 10275606 (ISSN) ; Talebi, A ; Ardakanian, R ; Shamsai, A ; Sharif University of Technology
2010
Abstract
The travel time of subsurface flow in complex hillslopes (hillslopes with different plan shape and profile curvature) is an important parameter in predicting the subsurface flow in catchments. This time depends on the hillslopes geometry (plan shape and profile curvature), soil properties and climate conditions. The saturation capacity of hillslopes affect the travel time of subsurface flow. The saturation capacity, and subsurface travel time of compound hillslopes depend on parameters such as soil depth, porosity, soil hydraulic conductivity, plan shape (convergent, parallel or divergent), hillslope length, profile curvature (concave, straight or convex) and recharge rate to the groundwater...
A novel method for production of foamy core@compact shell Ti6Al4V bone-like composite
, Article Journal of Alloys and Compounds ; Volume 656 , 2016 , Pages 416-422 ; 09258388 (ISSN) ; Sadrnezhad, S. K ; Sharif University of Technology
Elsevier Ltd
Abstract
This paper presents a novel method for fabrication of bone-like Ti6Al4V foamy core@compact shell composite for utilization as substitutive implant for cortical bone having porous core. Seven prototypes with core-diameters of 0, 6, 8, 10, 12, 14 and 16 mm surrounded by dense shells of respective thicknesses 8, 5, 4, 3, 2, 1 and 0 were produced by an innovative two-stage packing/compaction sintering method. Density, porosity, Young's modulus and compression strength of the prototypes depended on the core diameter. Mechanical strength and Young's modulus of 10@16 (10 mm core, 16 mm diameter prototypes) resembled that of the human ulna bone. Creation of foam at the center was achieved by...
The impact of ZrSiO4 nanoparticles addition on the microstructure and properties of dolomite based refractories
, Article Ceramics International ; Volume 43, Issue 16 , 2017 , Pages 13932-13937 ; 02728842 (ISSN) ; Karamian, E ; Gheisari Dehsheikh, H ; Sharif University of Technology
Abstract
Dolomite base refractories have advantages such as high refractoriness, potential to produce pure steel molten, high alkaline corrosion resistance, and economical for consumers. However, application of these refractories has been limited due to their high potential to hydration with atmosphere humidity. In this research work, the impact of ZrSiO4 nanoparticles addition on the physical, thermo-mechanical, mechanical, and microstructure of the dolomite base refractories is investigated. Also, XRD and SEM/EDX analyses were used for determining generated ceramic phases and microstructure evaluation, respectively. Up to 3 wt% ZrSiO4 nanoparticles were added to the compositions. Compositions fired...
Strain gradient based dynamic response analysis of heterogeneous cylindrical microshells with porosities under a moving load
, Article Materials Research Express ; Volume 6, Issue 3 , 2019 ; 20531591 (ISSN) ; Mohasel Afshari, B ; Barati, M. R ; Hamouda, A. M. S ; Sharif University of Technology
Institute of Physics Publishing
2019
Abstract
Forced vibration of a porous functionally graded (FG) cylindrical microshell due to a moving point load with constant velocity is studied for the first time. Through the thickness of microshell, there are even-type or uneven-type porosities. Therefore, material properties of the microshell become porosity-dependent and are described via modified power-law function. For micro-scale shells, small size effects due to non-uniform strain field can be considered via strain gradient theory (SGT). At first, the governing equations of the microshell are converted to new equations in Laplace domain. Then, time response of the microshell will be obtained implementing inverse Laplace transform...
Influence of imperfection on amplitude and resonance frequency of a reinforcement compositionally graded nanostructure
, Article Waves in Random and Complex Media ; 2019 ; 17455030 (ISSN) ; Alizadeh, A ; Oyarhossein, M. A ; Shavalipour, A ; Makkiabadi, M ; Habibi, M ; Sharif University of Technology
Taylor and Francis Ltd
2019
Abstract
This article investigates the influences of nonuniform imperfection on the dynamic amplitude and resonance frequency of the nanoshell reinforced with graphene nanoplatelet (GNP). The novelty of the current study is to consider the effects of porosity, thermal loading and graphene platelet reinforced composites on the dynamic behavior of the nanostructure. Three-length scale parameters (l0=5 h, l1=3 h, l2=5 h) in the modified strain gradient theory (MSGT) show a better agreement with MD simulation in comparison with other theories. Finally, the effects of different factors on the dynamic amplitude and resonance frequency of the porous nanostructure are examined in detail. © 2019, © 2019...
Transient response of porous inhomogeneous nanobeams due to various impulsive loads based on nonlocal strain gradient elasticity
, Article International Journal of Mechanics and Materials in Design ; Volume 16, Issue 1 , March , 2020 , Pages 57-68 ; Mohasel Afshari, B ; Barati, M. R ; Hamouda, A. M. S ; Sharif University of Technology
Springer
2020
Abstract
Transient vibration responses of a porosity-dependent functionally graded nanobeam under different impulsive loadings have been investigated in the context of non-local strain gradient theory. Three impulse loads of rectangular-type, linear-type and sine-type have been applied to top surface of nanobeam. Two porosity distribution types known as even and uneven are discussed. Governing equations of the nanobeam are solved via inverse Laplace transform approach to express the dynamic deflections. One can see that the transient response of nano-size beams is influenced by the type and location of pulse load, porosities volume fractions, porosities distributions, non-local and strain gradient...
Effect of transient liquid phase diffusion bonding on microstructure and properties of a nickel base superalloy rene 80
, Article Materials Science and Engineering A ; Volume 456, Issue 1-2 , 2007 , Pages 93-98 ; 09215093 (ISSN) ; Moeinifar, S ; Kokabi, A. H ; Sharif University of Technology
2007
Abstract
A nickel base superalloy Rene 80 was bonded in the as received cast condition using transient liquid phase diffusion bonding with a Ni-base interlayer. The bonding process was carried out at 1100 °C under argon and vacuum atmospheres for various hold times. The bonds then homogenized at 1206 °C for 1 and 2 h. Microstructures of bonds were studied with optical and scanning electron microscopy. Microstructure studies showed intermetallic compounds within the joint region. However, these intermetallic compounds were removed by a post-bond heat treatment at 1206 °C for 2 h. Shear and hardness tests were undertaken to determine the mechanical properties of bonded samples. Results showed that the...
Effect of microstructural constituents on the thermal fatigue life of A319 aluminum alloy
, Article Materials Science and Engineering A ; Volume 454-455 , 2007 , Pages 528-535 ; 09215093 (ISSN) ; Rajabi, M ; Nejati, E ; Khomamizadeh, F ; Sharif University of Technology
2007
Abstract
In this investigation, the effect of microstructural constituents on thermal fatigue resistance of A319 aluminum casting alloy was studied. For this purpose, both thermo-mechanical fatigue and thermal-shock fatigue experiments were performed in thermal cycling range between 40 and 250 °C. Following the results, samples with finer SDAS, lower porosity volume fraction and lower brittle intermetallic contents, as well as higher Si modification showed better thermal fatigue resistance. Moreover, T6 and T7 heat treatments appeared to be highly beneficial for thermal fatigue performance. According to the fractography analysis, porosities and coarse intermetallic phases were determined as the most...
Adhesive and cohesive properties by indentation method of plasma-sprayed hydroxyapatite coatings
, Article Applied Surface Science ; Volume 253, Issue 11 , 2007 , Pages 4960-4965 ; 01694332 (ISSN) ; Ziaei Moayyed, A. A ; Mesgar, A. S. M ; Sharif University of Technology
Elsevier
2007
Abstract
Adhesive and cohesive properties of the plasma-sprayed hydroxyapatite (HA) coatings, deposited on Ti-6Al-4V substrates by varying the plasma power level and spray distance (SD), were evaluated by an indentation method. The crystallinity and the porosity decreased with increasing both of these two parameters. The microhardness value, Young's modulus (E) and coating fracture toughness (K C ) were found to increase with a combinational increase in spray power and SD. The Knoop and Vickers indentation methods were used to estimate E and K C , respectively. The critical point at which no crack appears at the interface was determined by the interface indentation test. This was used to define the...
Prediction of porosity percent in Al-Si casting alloys using ANN
, Article Materials Science and Engineering A ; Volume 431, Issue 1-2 , 2006 , Pages 206-210 ; 09215093 (ISSN) ; Mousavi Anijdan, S. H ; Bahrami, A ; Sharif University of Technology
2006
Abstract
In this investigation a theoretical model based on artificial neural network (ANN) has been developed to predict porosity percent and correlate the chemical composition and cooling rate to the amount of porosity in Al-Si casting alloys. In addition, the sensivity analysis was performed to investigate the importance of the effects of different alloying elements, composition, grain refiner, modifier and cooling rate on porosity formation behavior of Al-Si casting alloys. By comparing the predicted values with the experimental data, it is demonstrated that the well-trained feed forward back propagation ANN model with eight nodes in hidden layer is a powerful tool for prediction of porosity...
Effects of resin and graphite content on density and oxidation behavior of MgO-C refractory bricks
, Article Ceramics International ; Volume 32, Issue 3 , 2006 , Pages 313-319 ; 02728842 (ISSN) ; Nemati, Z. A ; Faghihi Sani, M. A ; Sharif University of Technology
2006
Abstract
The effects of resin type and content as well as graphite content on physical and mechanical properties of MgO-C refractories, such as density, porosity and strength were studied. The samples were formulated with various amounts of graphite and resin, and their oxidation behavior was isothermally investigated using a thermo gravimeter (TG), in air and at a temperature ranges from 900 to 1300 °C. The results indicated that, low-viscosity resins improved compressibility, but it degraded the strength. Higher resin content also improved the compressibility, but it caused higher porosity after preheating at 600 °C. The results also showed that the porosity and density of tempered samples were...
Using genetic algorithm and artificial neural network analyses to design an Al-Si casting alloy of minimum porosity
, Article Materials and Design ; Volume 27, Issue 7 , 2006 , Pages 605-609 ; 02641275 (ISSN) ; Bahrami, A ; Madaah Hosseini, H. R ; Shafyei, A ; Sharif University of Technology
2006
Abstract
In this investigation a theoretical model based on artificial neural network (ANN) and genetic algorithm (GA) has been developed to optimize effective parameters on porosity formation in Al-Si casting alloys. The ANN theory was used to correlate the chemical composition and cooling rate to the amount of porosity. The GA and ANN were incorporated to find the optimal conditions for achieving the minimum porosity percent. By comparing the predicted values with the experimental data - earlier deduced by Dash et al. - it is demonstrated that the combined GA-ANN model is a useful and efficient method to find the optimal conditions for casting of Al-Si alloys associated with the minimum porosity...
Some physical properties of Pistachio (Pistacia vera L.) nut and its kernel
, Article Journal of Food Engineering ; Volume 72, Issue 1 , 2006 , Pages 30-38 ; 02608774 (ISSN) ; Mortazavi, A ; Safekordi, A ; Tabil, L. G ; Sharif University of Technology
2006
Abstract
Some physical and aerodynamic properties of pistachio nut and its kernel were determined in order to design processing equipment and facilities. In this study, several physical properties of pistachio nut and its kernel were evaluated as a function of moisture content in the range of 4.10-38.10% (w.b.). The length, width, height, shell splitting and unit mass of pistachio nut ranged from 16.07 to 17.25 mm, 12.41 to 12.75 mm, 10.98 to 12.24 mm, 3.59 to 4.47 mm and 0.90 to 1.30 g respectively as the moisture content increased. The respected value for pistachio kernel varied from 15.21 to 16.22 mm, 9.11 to 10.53 mm, 8.73 to 9.66 mm and 0.51 to 0.80 g, respectively. In pistachio nut, the...
Powder metallurgical fabrication and characterization of nanostructured porous NiTi shape-memory alloy
, Article Materials and Manufacturing Processes ; Volume 21, Issue 8 , 2006 , Pages 727-735 ; 10426914 (ISSN) ; Arami, H ; Keivan, H ; Khalifezadeh, R ; Sharif University of Technology
2006
Abstract
Production of NiTi alloy from elemental powders was conducted by mechanical alloying (MA) and sintering of the raw materials. Effects of milling time and milling speed (RPM) on crystallite size, lattice strain, and XRD peak intensities were investigated by X-ray analysis of the alloy. Powder compaction and sintering time and temperature effects on pore percentage of the as-mixed and the mechanically alloyed samples were empirically evaluated. The crystallite size of the mechanically alloyed Ni50Ti50 samples decreased with MA duration and with the milling speed. Depending on the crystal structure of the raw materials, the lattice strain increases with the milling duration. Metallographic...
Influence of imperfection on amplitude and resonance frequency of a reinforcement compositionally graded nanostructure
, Article Waves in Random and Complex Media ; Volume 31, Issue 6 , 2021 , Pages 1340-1366 ; 17455030 (ISSN) ; Alizadeh, A ; Oyarhossein, M. A ; Shavalipour, A ; Makkiabadi, M ; Habibi, M ; Sharif University of Technology
Taylor and Francis Ltd
2021
Abstract
This article investigates the influences of nonuniform imperfection on the dynamic amplitude and resonance frequency of the nanoshell reinforced with graphene nanoplatelet (GNP). The novelty of the current study is to consider the effects of porosity, thermal loading and graphene platelet reinforced composites on the dynamic behavior of the nanostructure. Three-length scale parameters (l 0=5 h, l 1=3 h, l 2=5 h) in the modified strain gradient theory (MSGT) show a better agreement with MD simulation in comparison with other theories. Finally, the effects of different factors on the dynamic amplitude and resonance frequency of the porous nanostructure are examined in detail. © 2019 Informa UK...
Presentation of a Model and Solving the Problem of Project Portfolio Selection Based on Project Scheduling using Two-Level NSGAII
, M.Sc. Thesis Sharif University of Technology ; Shadrokh, Shahram (Supervisor)
Abstract
This project aims to study a situation in which several projects must be selected. The decision makers should select a subset of these projects taking into account the limitation of resources and scheduling. Project selection models generally do not consider schedule of project activities as part of selection process. On the other hand, except the cases where only one project is under process in each period, prioritizing the selected projects is not optimal not considering their scheduling. Projects scheduling in project activities level may increase the complexity of decision making for portfolio selection and expand the area of search for selection of projects portfolio. Therefore, all the...
Design and Fabrication af a Bioceramic-Polymer Composite Scaffold Using Bioprinter for Regeneration of Osteochondral Tissue
, M.Sc. Thesis Sharif University of Technology ; Mashayekhan, Shohreh (Supervisor)
Abstract
In this work, we have used a 3D printer and unidirectional ice-templating technique in conjunction, to fabricate a novel composite scaffold to facilitate local osteochondral defects tissue regeneration with a cell-free approach. Using ice-templating to induce radially-aligned porosity formation in type I bovine collagen is known to expedite host cells' migration into the scaffold which their ECM secretion shifts cellular milieu toward that of its neighboring tissue layer. We used numerical analysis to design and optimize appropriate freeze-casting mold, finding the optimum value for pin height and metal slab depth to be 4mm and 14mm, respectively. Collagen content equivalent to 2%w/v was...
Effects of preheating temperature and cooling rate on two-step residual stress in thermal barrier coatings considering real roughness and porosity effect
, Article Ceramics International ; Vol. 40, Issue. 10 , December , 2014 , pp. 15925-15940 ; ISSN: 02728842 ; Farrahi, G. H ; Azadi, M ; Ghodrati, M ; Sharif University of Technology
Abstract
In this research, a finite element model was developed in order to simulate the two-step residual stress distribution of a thermal barrier coating system, considered to be used in diesel engine cylinder head, with a real roughness and real porosity. Two steps including the bond coat and the top coat deposition processes were taken into account. The real geometry of coating layers, including the roughness and the porosity, was also considered based on a scanning electron microscopy image. Then, effects of the convective heat transfer coefficient and initial substrate and substrate/bond coat preheating temperatures on the residual stress were studied. Obtained results illustrate that the...
On the effect of hydrogen and Fe on reproducibility of tensile properties in cast Al-Si-Mg alloys
, Article Materials Science and Engineering A ; Volume 565 , 2013 , Pages 278-284 ; 09215093 (ISSN) ; Davami, P ; Varahram, N ; Kim, S. K ; Sharif University of Technology
2013
Abstract
Gas porosities and Fe-rich phases and entrapped double oxide films (hereafter: oxides) are known to be the most detrimental defects in cast Al-Si-Mg alloys. The effects of H (gas porosities) and Fe (Β-Al5FeSi phase) on reproducibility of tensile properties in Al-7Si-0.35Mg alloy have been investigated in this study. Four different casting conditions (Low H-Low Fe, Low H-High Fe, High H-Low Fe and High H-High Fe) were studied. In each case, 30 tensile test samples were prepared by casting in a metallic mold and machining (total of 120 tensile test samples). Results of tensile test were analyzed by Weibull three-parameter analyses. The microstructures of samples were studied by optical...