70 research outputs found
On the influence of T-Stress on photoelastic analysis under pure mode II loading
No full textAccording to the classical definition for in-plane modes of crack deformation, the constant stress term T exists only in the presence of mode I. However, recent studies show that this term can exist inmode II conditions as well, and significantly affect the elastic stress field around the crack tip. These effects can be visualized using the experimental method of photoelasticity. Based on the analytical studies, presence of the T-stress in mode II cracks transforms the isochromatic fringe patterns from symmetric closed loops to asymmetric and discontinuous shapes. In this paper, presence of the T-stress in mode II cracks and its effects on the fringe patterns is experimentally investigated. The test specimens are Brazilian disks containing very sharp central cracks: experimental results indicate that these specimens contain negative values of T-stress. Experimental values are then compared to numerical results. To better understand the differences between experimental and numerical values, a thee dimensional analysis is performed with the finite element method: results show the influence of the real geometry of the crack front on the stress intensity factors
The Influence of Physical Rehabilitation Program on the Body Spatial Organization of the 8 Years Old Children with Posture Violation in the Frontal Plane and 1st and 2nd Degree Scoliosis
Get PDFKord Mahnaz. The Influence of Physical Rehabilitation Program on the Body Spatial Organization of the 8 Years Old Children with Posture Violation in the Frontal Plane and 1 and 2 Degree Scoliosis / Kord Mahnaz, O. Lazarieva // World Journal of Medical Sciences. – 2013. – № 8(3). – P. 271-275.Research was devoted for an actual problem of correction scoliosis to deformation and infringements of a bearing in a frontal plane in conditions. General educational establishment at 8 years Iran children was performed. The author offered the original program physical rehabilitations with application of exercises on restoration of vestibular function in conditions of general educational establishmen
Experimental Investigation of T-Stress Effects on photoelastic fringes in Brazilian Disk under Mode II Conditions.
No full textInvestigación sobre las potencialidades de la imagen caligráfica islámica para la pintura iraní contemporánea
No full textTesis inédita de la Universidad Complutense de Madrid, Facultad de Bellas Artes, leída el 24/05/2024En la cultura iraní, la palabra escrita ha ido más allá de sus funciones de documentación y comunicación y se ha transformado en una forma de arte. Los artistas iraníes han empleado su talento para producir estilos y patrones de escritura que se han aplicado, más allá de las páginas escritas, en diferentes formas de arte. En las últimas décadas, los artistas han enriquecido las escrituras islámica e iraní, dotándolas de variedad y belleza, y han producido muchas obras maestras, especialmente cuando se combina la caligrafía con la pintura...In Iranian culture, the written word has been carried beyond its functions of documentation and communication and has been transformed into a form of art. Iranian artists have employed their talents to produce styles and patterns of writing that have been applied, beyond the written pages, in different forms of art. In recent decades, artists have enriched Islamic and Iranian scripts endowing them with variety and beauty and have produced many masterpieces, particularly when calligraphy is combined with painting...Fac. de Bellas ArtesTRUEunpu
A participação política feminina no contexto da revolução iraniana : uma análise dos discursos de Mahnaz Afkhami (1994- 2016).
No full textPrograma de Pós-Graduação em História. Departamento de História, Instituto de Ciências Humanas e Sociais, Universidade Federal de Ouro Preto.Mahnaz Afkhami, ministra durante o regime Pahlavi durante a década de 1970, investigou
o movimento de mulheres no Irã a partir de suas perspectivas, sugerindo discussões sobre gênero,
patriarcado, emancipação, liberdade e direitos civis para as mulheres. Os artigos publicados pela
autora após a Revolução Iraniana, se referem ao contexto pre-revolucionário dos anos de 1960 e
1970, destacando seu papel como secretária geral da organização do governo, Women’s
Organization of Iran, no qual ela reivindicou pautas para ampliar a participação das mulheres no
Irã. A Women’s Organization of Iran foi um projeto desenvolvido de acordo com os esforços do
reinado Pahlavi para incentivar a modernização do Irã, seguindo o modelo europeu, o qual precisou
balancear as mudanças com uma sociedade heterogênea, suas tradições culturais e religiosas.
Embora Mahnaz Afkhami tenha desempenhado um papel significante como secretária geral
e ministra, suas perspectivas eram baseadas em teorias femininas que não se encaixavam nas
circunstâncias de grupos menos afortunados no Irã. A autora realizou um trabalho de tradução de
teorias em ações práticas, viajando ao interior do país para compreender os obstáculos do dia a dia
em que cada mulher se encontrava. Mahnaz Afkhami percebeu que perspectivas ocidentais não
eram suficientes para conscientizar mulheres em aldeias e áreas rurais. A partir dos estudos
póscoloniais e da história intelectual, essa investigação analisará os discursos de Mahnaz Afkhami
sobre o movimento de mulheres no Irã.Mahnaz Afkhami, which was a minister during the Pahlavi reign in the 1970’s, investigate
the women’s movement in Iran through her lens, suggesting discussions about gender, patriarchy,
emancipation, liberty and civil rights for women. The articles that the author had published after
the Iranian Revolution, talk about the 60’s and the 70’s prerevolutionary scenario, highlighting her
role as general secretary of the governmental organization Women’s Organization of Iran, in which
she had perceived agendas to increase the women’s participation in Iran. The Women’s
Organization of Iran was a project placed within the struggle of the Pahlavi’s reign to move Iran
into a modernized state, following european examples, which had to balance changes with an
heterogenous society, their cultural and religous tradition.
Although Mahnaz Afkhami had played a main role as both general secretary and minister,
her perspectives were based in a feminist theory that could not fit the circumstances that less
fortunate groups in Iran were in. The author had to translate the theory to practical actions, traveling
through the country to understand what were the daily struggles that each woman were placed.
Mahnaz Afkhami realized that western perspectives were not enough to raise women’s awareness
on the countryside and small villages. Based on a postcolonial studies and the intelectual history,
this investigation is going to analyse Mahnaz Afkhami’s discourses about the women’s movement
in Iran
On the influence of T-Stress on photoelastic analysis under pure mode II loading
Get PDFAccording to the classical definition for in-plane modes of crack deformation, the constant stress term T exists only in the presence of mode I. However, recent studies show that this term can exist in mode II conditions as well, and significantly affect the elastic stress field around the crack tip. These effects can be visualized using the experimental method of photoelasticity. Based on the analytical studies, presence of the T-stress in mode II cracks transforms the isochromatic fringe patterns from symmetric closed loops to asymmetric and discontinuous shapes. In this paper, presence of the T-stress in mode II cracks and its effects on the fringe patterns is experimentally investigated. The test specimens are Brazilian disks containing very sharp central cracks: experimental results indicate that these specimens contain negative values of T-stress. Experimental values are then compared to numerical results. To better understand the differences between experimental and numerical values, a thee dimensional analysis is performed with the finite element method: results show the influence of the real geometry of the crack front on the stress intensity factors
On the Mechanical Properties of Chiral Carbon Nanotubes
No full textCarbon nanotubes (CNTs) are specific structures with valuable characteristics. In general, the structure of each nanotube is defined by a unique chiral vector. In this paper, different structures of short single-walled CNTs are simulated and their mechanical properties are determined using finite element method. For this aim, a simple algorithm is presented which is able to model the geometry of single-walled CNTs with any desired structure based on nano-scale continuum mechanics approach. By changing the chiral angle from 0 to 30 degree for constant length to radius ratio, the effect of nanotube chirality on its mechanical properties is evaluated. It is observed that the tensile modulus of CNTs changes between 0.93-1.02 TPa for different structures, and it can be higher for chiral structures than zigzag and armchair ones. Also, for different chiral angles, the bending modulus changes between 0.76-0.82 TPa, while the torsional modulus varies in the range of 0.283-0.301TPa
Numerical Investigation of Size and Structure Effect on Tensile Characteristics of Symmetric and Asymmetric CNTs
No full textIn this research, the influence of structure on the tensile properties of single- walled carbon nanotubes (CNTs) is evaluated using molecular mechanics technique and finite element method. The effects of diameter, length and chiral angle on elastic modulus and Poisson’s ratio of armchair, zigzag and chiral structures are investigated. To simulate the CNTs, a 3D FEM code is developed using the ANSYS commercial software. Considering the carbon-carbon covalent bonds as connecting load-carrying beam elements, and the atoms as joints of the elements, CNTs are simulated as space-frame structures. The atomic potentials are estimated using harmonic simple functions. The numerical results show that by increasing the diameter and length to a certain amount, the size effect on tensile behavior of modeled nanotubes is omitted. In fact, for nanotubes with diameter over 2 nm and length over 36.5 nm the chiral angle is the only effective factor on the tensile properties. Also, it is found that the structure has a little effect on the elasticity modulus, which is about 4%. However, Poisson’s ratio can be affected significantly with chiral angle. Asymmetric structures with angles
Investigation of Chirality Effect on Axial and Torsional Buckling Behavior of SWCNTs Using Finite Element Method
No full textIn this paper, chirality effect on the buckling behavior of SWCNTs has been investigated. In order to explore the effect of chiral angle, all structures are used with the same length and diameter but different chiral angles. For modeling of chemical bonds between carbon atoms, potential energy of molecular mechanics theory and strain energies of a 3D beam element have been equalized. After calculating the element properties, the node coordinates have been determined using a computer code developed in MATLAB software. Then, ANSYS software is used to study the chirality effects on axial and torsional buckling load. Results show that the chiral angle has no significant influence on critical axial force. However, chiral angle is an effective parameter in torsional buckling. Chiral angle of 19.11 degree has the maximum critical torsional moment among all structures. In counter-clock-wise loading condition, chiral angle of 9.64 degree has the minimum critical torsional moment. Also, the direction of twisting (cw or ccw) is important and the difference between cw and ccw critical torsional moment reaches its maximum value for chiral angle of 15.48 degree
Quantitative analysis of cerebral white matter anatomy from diffusion MRI
Get PDFThesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2008.This electronic version was submitted by the student author. The certified thesis is available in the Institute Archives and Special Collections.Includes bibliographical references (p. 165-177).In this thesis we develop algorithms for quantitative analysis of white matter fiber tracts from diffusion MRI. The presented methods enable us to look at the variation of a diffusion measure along a fiber tract in a single subject or a population, which allows important clinical studies toward understanding the relation between the changes in the diffusion measures and brain diseases, development, and aging. The proposed quantitative analysis is performed on a group of fiber trajectories extracted from diffusion MRI by a process called tractography. To enable the quantitative analysis we first need to cluster similar trajectories into groups that correspond to anatomical bundles and to establish the point correspondence between these variable-length trajectories. We propose a computationally-efficient approach to find the point correspondence and the distance between each trajectory to the prototype center of each bundle. Based on the computed distances we also develop a novel model-based clustering of trajectories into anatomically-known fiber bundles. In order to cluster the trajectories, we formulate an expectation maximization algorithm to infer the parameters of the gamma-mixture model that we built on the distances between trajectories and cluster centers. We also extend the proposed clustering algorithm to incorporate spatial anatomical information at different levels through hierarchical Bayesian modeling. We demonstrate the effectiveness of the proposed methods in several clinical applications. In particular, we present our findings in identifying localized group differences in fiber tracts between normal and schizophrenic populations.by Mahnaz Maddah.Ph.D
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