Loading...
Search for:
tahani--masoud
0.117 seconds
Total 370 records
Edge effects of uniformly loaded cross-ply composite laminates
, Article Materials and Design ; Volume 24, Issue 8 , 2003 , Pages 647-658 ; 02641275 (ISSN) ; Nosier, A ; Sharif University of Technology
Elsevier Ltd
2003
Abstract
Interlaminar stresses resulting from bending of rectangular cross-ply composite laminates are determined using a layer wise laminate theory. Two types of laminates are considered. First a fully simply supported laminate subjected to bi-directional bending is analyzed. The results obtained from this theory are compared with those of the published three-dimensional elasticity solutions to verify the validity and accuracy of the present theory. Then laminates with two edges simply supported and the other two edges free are examined. The results indicate the presence of significant interlaminar stresses near the free edges. © 2003 Elsevier Ltd. All rights reserved
Free edge stress analysis of general cross-ply composite laminates under extension and thermal loading
, Article Composite Structures ; Volume 60, Issue 1 , 2003 , Pages 91-103 ; 02638223 (ISSN) ; Nosier, A ; Sharif University of Technology
2003
Abstract
An elasticity formulation for finite general cross-ply (symmetric and unsymmetric) laminates subjected to extension and/or a layerwise temperature distribution is developed. It is shown that the edge-effect problem of such laminates is actually a quasi-threedimensional problem and its stress analysis can be restricted to a generic two-dimensional cross-section of the laminates. A layerwise theory is used to investigate analytically the interlaminar stresses near the free edges of general cross-ply composite laminates. The results obtained from this theory are compared with those available in the literature. It is found that the theory can predict very accurately the stresses in the interior...
Three-dimensional interlaminar stress analysis at free edges of general cross-ply composite laminates
, Article Materials and Design ; Volume 24, Issue 2 , 2003 , Pages 121-130 ; 02641275 (ISSN) ; Nosier, A ; Sharif University of Technology
2003
Abstract
A layerwise theory is used to investigate analytically the interlaminar stresses near the free edges of general cross-ply composite laminates under uniform axial extension. Laminates with finite dimensions are considered and full three-dimensional stresses in the interior and the boundary-layer regions are calculated. The results obtained from this theory are compared with those available in the literature. It is found that the edge-effect problem of general cross-ply laminates is actually a quasi three-dimensional problem and its stress analysis can be restricted to a generic two-dimensional cross-section of the laminates. © 2003 Elsevier Science Ltd. All rights reserved
Accurate determination of interlaminar stresses in general cross-ply laminates
, Article Mechanics of Advanced Materials and Structures ; Volume 11, Issue 1 , 2004 , Pages 67-92 ; 15376494 (ISSN) ; Nosier, A ; Sharif University of Technology
2004
Abstract
Reddy's layerwise theory is used to investigate analytically the interlaminar stresses near the free edges of general (unsymmetric and symmetric) cross-ply composite laminates with various boundary conditions subjected to mechanical and hygrothermal loadings. Laminates with finite dimensions are considered and full three-dimensional stresses in the interior and the boundary-layer regions are calculated. The results obtained from this theory are compared with those available in the literature. It is found that the theory can predict very accurately the stresses in the interior region and near the free edges of both finite and long laminates
Explaining the Concept of Civilization by using Theory of Constructive Perceptions with Emphasis on Knowledge and Technology as Components of Civilization
, M.Sc. Thesis Sharif University of Technology ; Taghavi, Mostafa (Supervisor)
Abstract
The purpose of writing this thesis is to arrive at the concept of civilization. And in this process, using the constructive perception. My approach in constructive perception is different with approach of Allameh tabatabaei in constructive perception. In first chapter defining constructive perception as the perception that mind by analogy between two consepts makes the non-real relations and attributes it deliberated to the reality (the parties). Meanwhile, should have been constructive perception is the intermediary that stimulation our sense abut reality. These feelings can be tenderness or hatred or fear and hope and ... . In the second chapter we will show that the use of technology...
On thermomechanical stress analysis of adhesively bonded composite joints in presence of an interfacial void
, Article Composite Structures ; Volume 130 , October , 2015 , Pages 116-123 ; 02638223 (ISSN) ; Yousefsani, S. A ; Sharif University of Technology
Elsevier Ltd
2015
Abstract
This paper deals with analytical thermomechanical stress analysis of adhesively bonded composite joints in presence of a structural imperfection in the form of an interfacial void within the adhesive layer based on the full layerwise theory (FLWT). The joints are subjected to mechanical tension, uniform temperature change, or steady-state heat conduction. The proposed adhesive joint is divided into three distinct regions along its length and a large number of mathematical plies through its thickness. Three sets of fully coupled governing equilibrium equations are derived employing the principle of minimum total potential energy. The three-dimensional nonlinear interlaminar stress...
Deformation and stress analysis of circumferentially fiber-reinforced composite disks
, Article International Journal of Solids and Structures ; Volume 42, Issue 9-10 , 2005 , Pages 2741-2754 ; 00207683 (ISSN) ; Nosier, A ; Zebarjad, S. M ; Sharif University of Technology
2005
Abstract
A semi-analytical method is developed for the analysis of deformation and three-dimensional stress field in rotating annular disks made of cylindrically orthotropic nested rings. The method is based on a layerwise theory and the Hamilton principle. The proposed method is applied to calculate in-plane and out-of-plane stresses in a rotating disk made up of two nested rings that is rigidly fixed (or free) at the inner boundary and is free at the outer boundary. The computed results are compared with those obtained from the finite element method. It is found that because of discontinuity of material properties, the stress field is three-dimensional at the interface of two rings. © 2004 Elsevier...
Analytical stress analysis of rotating composite beams due to material discontinuities
, Article Composites Technologies For 2020 ; 2004 , Pages 223-228 ; 9781855738317 (ISBN) ; Nosier, A ; Rezaeepazhand, J ; Zebarjad, S. M ; Sharif University of Technology
Woodhead Publishing Limited
2004
Abstract
Material discontinuity could cause in-plane stress gradients that it arises interlaminar stresses in regions of sudden transition of material properties. A layerwise laminated beam theory that is a modification of a layerwise laminated plate theory is developed and it is used to analyze analytically the interlaminar stresses at material discontinuities in rotating composite beams. Equations of motion are obtained by using Hamilton's principle. It is assumed that the beam is divided into two regions with different layups which are joined together. The predicted interlaminar stress distributions at the ply interfaces are shown to be in good agreement with comparative three-dimensional finite...
Inferring dynamic diffusion networks in online media
, Article ACM Transactions on Knowledge Discovery from Data ; Volume 10, Issue 4 , 2016 ; 15564681 (ISSN) ; Hemmatyar, A. M. A ; Rabiee, H. R ; Ramezani, M ; Sharif University of Technology
Association for Computing Machinery
2016
Abstract
Online media play an important role in information societies by providing a convenient infrastructure for different processes. Information diffusion that is a fundamental process taking place on social and information networks has been investigated in many studies. Research on information diffusion in these networks faces two main challenges: (1) In most cases, diffusion takes place on an underlying network, which is latent and its structure is unknown. (2) This latent network is not fixed and changes over time. In this article, we investigate the diffusion network extraction (DNE) problem when the underlying network is dynamic and latent. We model the diffusion behavior (existence...
Inferring the Diffusion Network in Dynamic Online Social Networks
, Ph.D. Dissertation Sharif University of Technology ; Afshin Hemmatyar, Ali Mohammad (Supervisor) ; Rabiee, Hamid Reza (Supervisor)
Abstract
The emergence of online social networks (OSN) has encouraged scientists to investigate them more deeply due to availability of excessive data and increased computational power. Diffusion is a fundamental process taking place in such networks. The spread of news, ideas, influence and diseases are examples of diffusion in social networks. The importance of information diffusion in different disciplines such as economics, politics and social behavior has motivated us to study diffusion networks in this thesis. Diffusion’s behavior is strongly influenced by the underlying network in social networks. Despite this fact most research done in this area ignores the dynamics of the underlying network....
Optimization of Load Distribution at the Bone-Implant Interface in Porous Coated Implants ''A Micromechanical Study Using FEM'
, M.Sc. Thesis Sharif University of Technology ; Katoozian, Hamid Reza (Supervisor) ; Ahmadian, Mohammad Reza (Supervisor) ; Zohoor, Hassan (Supervisor)
Abstract
Loosening and gap opening at the bone-implant interface depends on several physiological and mechanical factors such as bone remodeling, stress concentration, and variation in load transfer pathway. Since fracture of orthopedic material at the interface is one of the major failure mode of total joint implants, this study focused on the micromechanical behavior of the interface. Using a two-dimensional FE model, with pure compressive, tensile, and shearing forces applied on bone or cement, ratio of the stress at the interface to the applied stress has been calculated. Stress distribution was considered as a function of porosity,angle of bead contact to surface, as well as size of bead for two...
Long Term Effective Factors on House Price of Metropolises of Iran
, M.Sc. Thesis Sharif University of Technology ; Nili, Masoud (Supervisor)
Abstract
The notable share of housing sector in GDP (approximately five percent) shows this sector’s relation with macroeconomic activities. On the other hand, House as an asset leads housing sector to be affected by monetary and fiscal variables. A dynamic panel data was used in this study to evaluate the relations between housing sector and some macroeconomic variables in metropolises of Iran. As results show, in long term growth of liquidity, GDP per capita and sharp ratio have positive effects, and land per capita has negative effect on housing price in metropolises of Iran. Price increases have not been equal in different cities. Inequality of land price between metropolises and between...
Estimating an Index of Iran’s Informal Economy in 1350-1386 With Concentration on the Impact of Government’s Intervention by EMIMIC Model (The Multiple Indicators-Multiple Causes Model and Error-Correction Model)
, M.Sc. Thesis Sharif University of Technology ; Nili, Masoud (Supervisor)
Abstract
In this research, an Index of Iran informal economy in response to the government interventions in credit, labor and product markets is stimated by EMIMIC model. To do this, first these interventions are measured using principal components analysis. In the model, the variables GDP and employment are used as indicators and taxation rates, government distortions in credit, labor and product markets, government expenditure, per capita income, unemployment and inflation as causes of the informal economy. We conclude these government interventions have affected Iran informal economy and their influence is more than indirect interventions influence such as taxation. The estimated index of Iran...
Water Quality Modeling of Urban Streams
, M.Sc. Thesis Sharif University of Technology ; Tajrishy, Masoud (Supervisor)
Abstract
With altering natural state and increasing impervious surfaces, traditional urbanization leads to deteriorating the environment and water catchments. During the years most efforts in order to control the urban runoff outflow, have been focused on quantity; and awareness about improving water quality has been raised just in the last few years and, which emphasizes on pollution source control. Standard water quality sampling methods are time consuming, expensive and because of sampling in broad geographic areas, difficult; however modeling is a more efficient way in assessing water quality and as worries about non-point source pollution grows, different kinds of models have been used to...
The Political Economy Aspects of the Redistributive Role of Government in a General Equilibrium Micro-founded Macro Model
, M.Sc. Thesis Sharif University of Technology ; Nili, Masoud (Supervisor)
Abstract
The role of government in economy has been a controversial subject in economics. Lately, there has been some fundamental change in evaluating this subject. One could mention two of these as 1) realizing the importance of micro-founded macro model for evaluating policy, and 2) taking into consideration the rent-seeking behavior of politicians. In this research, a general equilibrium in a micro-founded macro model will be discussed and then in political economics framework, the effect of government on this equilibrium will be investigated. Only the redistribution role of government has been considered. First, the model in which a benevolent government is seeking optimal policy is Discussed....
Measurement of Gini Coefficients by Means of Household’s Special CPI in Iran(1984-2005)
, M.Sc. Thesis Sharif University of Technology ; Nili, Masoud (Supervisor)
Abstract
Gini coefficient is the most prevalent index for the measurement of inequality and is usually extracted by means of nominal variables based on income or expenditures of households. In this study we have extracted more accurate Gini coefficients. By using the raw data of Households Budget Survey (HBS) and STATA software, a special CPI for each household of the sample is extracted. Subsequently nominal expenditures are deflated by these special CPIs, and at last, Gini coefficients are extracted from real expenditures. Our findings indicate that in recent years, extracted Gini coefficients are remarkably higher than prevailing ones.
Parametric Evaluation of the Y- Shaped Bracing Frame and Introducing a New Method for Design
, M.Sc. Thesis Sharif University of Technology ; Mofid, Masoud (Supervisor)
Abstract
This paper investigates the behavior of the Y-shaped bracing system. Because of the special type of eccentricity in this system, the behavior of the frame is strongly dependent on the geometrical changes of the braces. So that even in the elastic region, it shows the geometrically nonlinear behavior. The amount of eccentricity is very effective on the nonlinear behavior of the frame. Also the ratio of cross sections of the bracing members has a very important impact on the expected performance of the frame. The results show that this system tolerates large displacements, and can act like a base isolation system. Firstly, using a two-dimensional accurate modeling related to the geometrical...
Assessment of Seismic Behavior Factor of Irregular Midrise Steel Structure
, M.Sc. Thesis Sharif University of Technology ; Mofid, Masoud (Supervisor)
Abstract
The Overstrength, Ductility and the Response Modification Factor (R) for 70 steel X-braced , Inverted-V-Braced and Offcenter Bracing System frames were evaluated by performing pushover analysis of model structure with various stories (3,6,9,12&15 story) and span length (4,6&8 meter). Some result were compared with those from nonlinear dynamic analysis. According to the analysis result the R factors obtained from nonlinear dynamic analysis are 15% more than obtained from pushover analysis and R factors computed from pushover analysis were generally smaller than the values given in the design codes. R factors in Irregular structure in height are about 90% of R values in regular structure in...
Synthesis of γ-Fe2O3 Nanoparticles by Gelatin Mediator and Synthesis of γ-Fe2O3/SiO2/PCA/Ag-NPs Nanostructure Drug Delivery System
, M.Sc. Thesis Sharif University of Technology ; Pourjavadi, Ali (Supervisor)
Abstract
Maghemite (γ-Fe2O3) nanoparticles were produced after high temperature oxidation of gelatin-Fe3O4 nanocomposite, obtained from a common coprecipitation process of Fe2+ and Fe3+ ions in an alkaline medium in the presence of a gelatin protein as an effective mediator. Size, shape, surface morphology and magnetic properties of the prepared γ-Fe2O3 nanoparticles were characterized using XRD, FTIR, TEM, SEM and VSM data. The results revealed that primary, gelatin-Fe3O4 nanocomposite had been formed and next, the gelatin decomposition in furnace produced a spinel structure of γ-Fe2O3. The effects of furnace temperature and time of heating together with the amount of gelatin on the produced...
On The Behavior of Low-Rise, Irregular, Dual Structures
, M.Sc. Thesis Sharif University of Technology ; Mofid, Masoud (Supervisor)
Abstract
The Response modification factor R represents the behavior of the structure such as ductility, overstrength and the inherent redundancy. This factor shall be defined according to the type of lateral force resisting system. However, there are some complexities and/or uncertainties in codes related to the R factor according to the height, form of irregularities and structural systems. Therefore, from the scientific point of view as well as reliability, it is very clear that the R factor cannot be similar for all kinds of structures, categorized as a specific group. In this investigation, assuming a low-rise, vertically irregular structure with a heliport which has a dual structural system...