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kazemi-bazardehi--roohollah
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A Criterion for Detection of Delamination in Laminated Composite Beams and Plates Based on Modal Analysis of Damaged Structure
,
Ph.D. Dissertation
Sharif University of Technology
;
Kouchakzadeh, Mohammad Ali
(Supervisor)
Abstract
In this study, irregularities of the mode shapes are utilized to determine the delamination situation in a composite laminated beam. Modal analysis is used to obtain the mode shapes of the beam; afterwards, the mode shapes are filtered to extract their irregularities. Presence of any delamination and its situation (number, size and location along the length and thickness of the beam) affects the extracted irregularities. Here, detection of delamination is based on these irregularities of the mode shapes. One of the most important advantages of this method is that unlike many other similar methods, in many cases, the mode shapes of damaged structure are sufficient and the exact mode shapes...
Detection of delamination in composite laminated plates using filtered mode shapes
, Article Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science ; Volume 226, Issue 12 , 2012 , Pages 2902-2911 ; 09544062 (ISSN) ; Kouchakzadeh, M. A ; Sharif University of Technology
2012
Abstract
Filtered mode shapes are used to detect the presence, location, size and shape of the delaminations in composite laminated plates with various boundary conditions. This method is the extension of a previous study by the authors on the delamination detection in the beams using irregularities of the mode shapes. The mode shapes are filtered to separate the smooth and irregular parts. Presence and situation of delamination affects these separated parts, and these effects are used to detect the delamination. Here, two new indicators, named 'slope of smooth part' and 'irregularities in the slope of smooth part', are introduced to increase the clarity of detected damage and reduce the noisy...
Optimum Design Of Wave Mitigating Multi phase FGMs
, M.Sc. Thesis Sharif University of Technology ; Tvakkoli, Roohollah (Supervisor)
Abstract
Functionally graded materials (FGMs) are categorized in a branch of composite materials in which the local volume fraction of contributing phases are not fixed throughout the spatial domain, but vary gradually as a function of position. This spatial variation leads to the gradual variation of physical and mechanical properties inside the materials. It provides us the opportunity of designing multiple purpose materials by the variation of local volume fractions according to our goal. The optimal distribution of local volume fractions is a function of the spatial domain geometry and loading conditions, and in general situations, due to the complexity of the problem, it is not possible to...
A mixed integer-programming model for periodic routing of special vessels in offshore oil industry
, Article International Journal of Industrial Engineering : Theory Applications and Practice ; Volume 22, Issue 5 , 2015 , Pages 524-548 ; 10724761 (ISSN) ; Yazdeli Roohollah, I ; Sharif University of Technology
University of Cincinnati
2015
Abstract
In order to maintain the production of offshore oil wells, the National Iranian Oil Company periodically services facilities and equipment located in oil wellheads with mobile wellhead servants. It also gives technical supports to oil wellheads and mobile wellhead servants with supporter vessels. Due to supply limitations, there are not enough special vessels (namely supporter vessels and mobile wellhead servants) compared to the number of oil wellheads. The failure of special vessels to service oil wellheads and supporter vessels to technically support mobile wellhead servants based on a predetermined plan, will lead to considerable loss in production performance of oil wells and hence...
Stability Analysis of a Beam Subjected to Axial, Bending and Torsional Follower Loads on the Tip
, M.Sc. Thesis Sharif University of Technology ; Dehghani Firouzabadi, Roohollah (Supervisor)
Abstract
Because the structural stability is directly related with structural damage, it is considered one of the most important issues in the industry. One of the applied cases in the stability issue discuss about the stability of the beam under follower loads. Follower loads obtained from aerodynamic pressure, rocket’s thrust, dry friction of the rotating disk, drilling and etc. Because the follower loads are always perpendicular to the beam cross section, thus with changing the angle of their location, their directions are changed. Spatial dependence makes a non-conservative and dynamic problem. So these loads causes dynamic instability that say flutter. In this study, the stability of a...
An Empirical Investigation of the Damping of Liquid Oscillations in Cylindrical Tanks with Vertical Baffles
, M.Sc. Thesis Sharif University of Technology ; Dehghani Firouzabadi, Roohollah (Supervisor)
Abstract
In this study, an analytical investigation of the hydrodynamic damping due to vertical baffles in circular cylindrical storage tanks is investigated. A lot of research about damping characteristics of different types of baffles has been done but because of specific applications of vertical baffles, studies are limited in this case. For analytical approach the average rate of energy dissipation is obtained with using the solution of Laplace’s equation by estimation the rate of the work done by baffles drag force to the oscillatory flow. The analytical solution validate by a series of experiments that conducted at the Langley Research Center of the National Aeronautics and Space...
Analytical and Experimental Study of Transverse Vibration of Ulerr-Bernoulli Beam with Dry Friction Boundary Condition
, M.Sc. Thesis Sharif University of Technology ; Dehghani Firouzabadi, Roohollah (Supervisor)
Abstract
The dry friction and its effect on the dynamics and vibrations of structures have always been one of the remarkable engineering issues. In the structures of engineering, dry friction mostly exists at the joints of structures and substrates and dry friction can lead to the nonlinearity and even chaos in the vibration of structures. There are different theories for the friction modeling and the most famous theory is the relation between the proportional ratio of the force of friction and perpendicular force to the surface. The main characteristic of friction as a damper force is the change of direction along with change in the direction of velocity. In the present study, at first, the nature...
Torsional Flexural Stability Analysis of Narrow Section Beam Subjected to Moving Mass
,
M.Sc. Thesis
Sharif University of Technology
;
Dehghani Firouzabadi, Roohollah
(Supervisor)
Abstract
Long thin rectangular beams are used in many industrial engineering including railways, aerospace and etc. Beam subjected to moving mass is one of the classic problems in mechanics and vibrations of beams and have been studied by many researchers. In most of done works, the moving mass was assumed to be small compared to beam mass and only acceleration effect of mass was considered. Also in many of researches only bending of beams was studied. Moving mass imposes 2 type of force in the supporting beam, first one is weight and the other is due to motion of mass and contains lateral, coriolis and centrifugal acceleration effects. In addition, due to the particular geometry considered (narrow...
Investigation and Optimization of Structural Parameters of an Elastic Flapping Wing
, M.Sc. Thesis Sharif University of Technology ; Dehghani Firouzabadi, Roohollah (Supervisor)
Abstract
In this thesis, effects of bending and torsional elasticity of a flapping wing on its average lift and input power are studied, using a semi-analytic method. Bending stiffness and torsional rigidity of wing spar, wing mass ratio and chordwise and spanwise center of gravity, also spar location are considered as variables for controlling elastic behavior of the wing.Governing integral equation is derived using Hamilton principle via modified quasi aerodynamic and linear Green-Lagrange strain tensor. Also an idealized flapping pattern is used to maximize average acceleration during each cycle. Next, integral equation is converted to a set of ordinary differential equations by means of Galerkin...
Ant colony algorithm for the shortest loop design problem [electronic resource]
, Article Computers and Industrial Engineering, Elsevier ; Volume 50, Issue 4, August 2006, Pages 358–366 ; Kazemi, Morteza ; Sharif University of Technology
Abstract
In this paper, a new algorithm for solving the shortest loop design problem is presented. The shortest loop design problem is to find the shortest loop for an automated guided vehicle covering at least one edge of each department of a block layout. In this paper, first it is shown that this problem can be represented as a graph model. The properties of the presented model enable us to design a meta-heuristic based on ant colony system algorithm for solving the shortest loop design problem. Computational results show the efficiency of our algorithm in compare to the other techniques
Propositional attitudes as commitments: unleashing some constraints
, Article Dialogue-Canadian Philosophical Review ; Volume 59, Issue 3 , 2020 , Pages 437-457 ; Sharif University of Technology
Cambridge University Press
2020
Abstract
In a series of articles, Asbjorn Steglich-Petersen and Nick Zangwill argue that, since propositional attitude (PA) ascription judgements do not behave like normative judgements in being subject to a priori normative supervenience and the Because Constraint, PAs cannot be constitutively normative.1 I argue that, for a specific version of normativism, according to which PAs are normative commitments, these arguments fail. To this end, I argue that commitments and obligations should be distinguished. Then, I show that the intuitions allegedly governing all normative judgements do not even purport to hold for commitment-attributing judgements. Copyright © Canadian Philosophical Association 2020
Commitment, norm-governedness and guidance
, Article Acta Analytica ; 2020 ; Sharif University of Technology
Springer
2020
Abstract
A number of philosophers have argued that there is a basic problem in the no-guidance argument against content normativism. The problem is that the argument restricts the essential normativity of intentional states to the formation of these states being guided by certain norms. But it is suggested that the essential norm-governedness of intentional states can be equally plausibly construed as the assessability of these states by norms, which does not imply complying with them. Although I concur with the problem diagnosed in the no-guidance argument, I take issue with the alternative conception of normativity which is put forward. In its stead, I argue that considering intentional states as...
Commitment, norm-governedness and guidance
, Article Acta Analytica ; Volume 36, Issue 2 , 2021 , Pages 213-228 ; 03535150 (ISSN) ; Sharif University of Technology
Springer Science and Business Media B.V
2021
Abstract
A number of philosophers have argued that there is a basic problem in the no-guidance argument against content normativism. The problem is that the argument restricts the essential normativity of intentional states to the formation of these states being guided by certain norms. But it is suggested that the essential norm-governedness of intentional states can be equally plausibly construed as the assessability of these states by norms, which does not imply complying with them. Although I concur with the problem diagnosed in the no-guidance argument, I take issue with the alternative conception of normativity which is put forward. In its stead, I argue that considering intentional states as...
Causal relations and abraham’s dilemma: a Qur’anic perspective
, Article Sophia ; 2021 ; 00381527 (ISSN) ; Sharif University of Technology
Springer Science and Business Media B.V
2021
Abstract
Abraham’s Dilemma is the conjunction of three jointly inconsistent propositions: (i) God’s commands are never morally wrong, (ii) God has commanded Abraham to kill his innocent son, and (iii) killing innocent people is morally wrong. Drawing on an overlooked point from the Qur’an regarding the content of the command as well as a conceptual analysis of intentional action, this paper proposes a novel solution to the dilemma by discarding proposition (ii) in a new way. Current approaches to rejecting proposition (ii) tend to appeal to epistemic failure on the side of Abraham. In my approach, which draws on the so-called accordion effect in intentional action, God’s command is interpreted in...
Still committed to the normativity of folk psychology
, Article Philosophical Explorations ; 2021 ; 13869795 (ISSN) ; Sharif University of Technology
Routledge
2021
Abstract
In what sense can one claim that intentional explanations are essentially normative, given that people’s actions and thinking are replete with various irrationalities, yet are still pretty well explained by this explanatory framework? This article provides a novel response to this enduring objection. First, following Brandom, it is suggested that, to understand the normativity of intentional states, we should countenance and distinguish between two normative categories of commitment and entitlement, only the former of which is argued to be essential for intentional explanations. Conflating these two normative dimensions is noted to be one of the main sources of the objections leveled against...
Causal relations and abraham’s dilemma: a Qur’anic perspective
, Article Sophia ; Volume 61, Issue 2 , 2022 , Pages 309-318 ; 00381527 (ISSN) ; Sharif University of Technology
Springer Science and Business Media B.V
2022
Abstract
Abraham’s Dilemma is the conjunction of three jointly inconsistent propositions: (i) God’s commands are never morally wrong, (ii) God has commanded Abraham to kill his innocent son, and (iii) killing innocent people is morally wrong. Drawing on an overlooked point from the Qur’an regarding the content of the command as well as a conceptual analysis of intentional action, this paper proposes a novel solution to the dilemma by discarding proposition (ii) in a new way. Current approaches to rejecting proposition (ii) tend to appeal to epistemic failure on the side of Abraham. In my approach, which draws on the so-called accordion effect in intentional action, God’s command is interpreted in...
Still committed to the normativity of folk psychology
, Article Philosophical Explorations ; Volume 25, Issue 1 , 2022 , Pages 58-74 ; 13869795 (ISSN) ; Sharif University of Technology
Routledge
2022
Abstract
In what sense can one claim that intentional explanations are essentially normative, given that people’s actions and thinking are replete with various irrationalities, yet are still pretty well explained by this explanatory framework? This article provides a novel response to this enduring objection. First, following Brandom, it is suggested that, to understand the normativity of intentional states, we should countenance and distinguish between two normative categories of commitment and entitlement, only the former of which is argued to be essential for intentional explanations. Conflating these two normative dimensions is noted to be one of the main sources of the objections leveled against...
Innovative Team Climate, Teamwork Quality and Team Performance in Software Development Teams
, M.Sc. Thesis Sharif University of Technology ; Kermanshah, Ali (Supervisor)
Abstract
In this dissertation, our aim is to evaluate a model linking “Teamwork Quality” and “Innovative Team Climate”. Teamwork Quality is defined as the quality of interactions among team members that includes six dimensions: “Communication”, “Coordination”, “Balance of Contribution”, “Mutual Support”, “Effort”, and “Cohesion”. Innovative Team Climate refers to shared perceptions of team policies, practices and procedures in support of innovation. This construct is composed of four dimensions: “Vision”, “Participation Safety”, “Task Orientation”, and “Support of Innovation”. Firstly, we hypothesized that there are positive relations between Innovative Team Climate and Teamwork Quality itself and...
Comparison Between Methods Of Synchronization In A Queue With Finite Customer Population
, M.Sc. Thesis Sharif University of Technology ; Mahlooji, Hashem (Supervisor)
Abstract
One technique to reduce variance of output in comparing two or more systems via simulation is random number synchronization. the primary technique for achieving synchronization is to assign an independent seed to each random process and then use the same collection of seeds across all systems . Another way of synchronization in systems with limited customer population is to assign different seed to each customer (transaction) and then use the same collection of seeds across all systems. The main Question to be considered here is which of these methods of synchronization can better reduce variance of output in a queue with finite customer population
Genco's Bidding Strategy in Day-Ahead Energy Market Considering Demand Response
, M.Sc. Thesis Sharif University of Technology ; Ehsan, Mehdi (Supervisor)
Abstract
Since 1980s the electricity market has been gradually evolving from a monopoly market into a liberalized one for encouraging competition and improving efficiency. This brings the opportunity for generation companies (Gencos) to make more profits while embracing more risks of not being dispatched. Therefore, it has become a core interest for the Gencos to develop optimal bidding strategies to maximize the profits and minimize the risks while participating in such a competitive market. Error of determining day-ahead electricity price is one of the sources of the risk. Energy price has a high impact on bidding strategy optimization process. So it should be determined with low error which is not...