Influence of Control Elements in Numerical Simulation of Ship Motions

, M.Sc. Thesis Sharif University of Technology Mehdi Hoseyni, Amin (Author) ; Seif, Mohammad Saeed (Supervisor)

Abstract

Ship motion is one of the most complicated problems in hydrodynamics. These motions accompany with non linear phenomena and their modeling is very difficult. Analytical solution for governing equations for such problems is not possible and experimental study is very expensive. In this state we need remarkable time for investigating of influences of environmental condition changes. In previous research done by Jahanbakhsh and Panahi,a software created that could solve fluid domain and rigid body equations. But the software needs to be developed in some aspects. Aim of this research is expanding of rigid body motion section of software. The software is capable of getting force or moment and...

The Effect of Rolling on the Mechanical Properties and Microstructure of Dissimilar Friction Stir Welded AA1050 – AA6082-T6 Sheets

, M.Sc. Thesis Sharif University of Technology Hoseyni, Sajad (Author) ; Kokabi, Amir Hossein (Supervisor) ; Kazeminezhad, Mohsen (Co-Advisor)

Abstract

One of the limitations of friction stir welding process is joining of sheets with low thickness. Interference ways for these limitations are joint in higher thicknesses and thickness reduction in included joint samples. In this study, in the first process, with the optimization of the variables affecting the process, joint was performed using visual inspection, mechanical properties and micro structural studies. In the next process, using the rolling operation for the reduction percent of different thicknesses, the most appropriate route was chosen. 1050 aluminum sheets (1050 and 6082-T6) with a thickness of 3 mm were welded using friction stir welding in tool rotary speeds of 1200 and 800...

Adversarial Attack to Deep Learning Networks via Imperceptible Sparse Perturbation

, M.Sc. Thesis Sharif University of Technology Heshmati, Alireza (Author) ; Ghaemmaghami, Shahrokh (Supervisor) ; Marvasti, Farokh (Supervisor) ; Amini, Sajad (Co-Supervisor)

Abstract

Nowadays, methods based on deep learning networks are the most effective artificial in telligence methods. Although they have achieved success in various fields (such as machine vision and object recognition), practical and experimental cases show the fragility of deep learning networks against perturbations and unwanted changes of the input pattern. All these perturbations must be in a way that the main class of the perturbed input pattern can be rec ognized by human, but the network makes a mistake in recognizing its correct class. This thesis seeks a more accurate evaluation by designing adversarial attacks such that the main class of the adversarial pattern is detectable by human...

A new and optimal architecture for applying association rule mining algorithms on grid

, Article 2007 IADIS European Conference on Data Mining, DM 2007, part of the 1st IADIS Multi Conference on Computer Science and Information Systems, MCCSIS 2007, 3 July 2007 through 8 July 2007 ; 2020 , Pages 230-232 Bouyer, A ; Arasteh, B ; Karimi, M. B ; Hoseyni, M. J ; Bouyer, A ; Movaghar, A ; Sharif University of Technology

IADIS Press 2020

Abstract

Grid computing is the on-demand sharing of computing resources with in a tightly-coupled network to solve certain problems. One of the main topics is knowledge discovery and data mining. By using grid computing, we can solve this problem. To achieve these very ambitious goals, we present an architecture for applying Association rule mining algorithms on grid environment. Association rule mining seeks to discover associations among transactions encoded in a database on each machine and then send result to related coordinator. This new architecture is powerful and rapid. We tried to compare our method with a serial processing. Our experimental results show that by using the new architecture on...

Dynamic response of metal foam FG porous cylindrical micro-shells due to moving loads with strain gradient size-dependency

, Article European Physical Journal Plus ; Volume 134, Issue 5 , 2019 ; 21905444 (ISSN) Sajad Mirjavadi, S ; Forsat, M ; Barati, M. R ; Abdella, G. M ; Mohasel Afshari, B ; Hamouda, A. M. S ; Rabby, S ; Sharif University of Technology

Springer Verlag 2019

Abstract

The dynamic characteristics of functionally graded (FG) metal foam cylindrical micro-scale shells in contact with a moving load will be analyzed thorough this paper accounting for strain-gradient size-dependency. In the material structure of a metal foam, pores can diffuse uniformly or non-uniformly. Based upon Laplace transform, the dynamical governing equations of the first-order micro-shell model can be established in a new domain. In order to go back into the time domain, an inverse Laplace transform will be required. Thus, on can express the time response or dynamic deflection of the micro-shell under moving load. In the presented results, it is easy to see the prominence of...