Durability Investigation and Fatigue Life Prediction Modelling for Pre-orroded AZ31 Alloy

, Ph.D. Dissertation Sharif University of Technology Shams Arjmand, Madjid (Author) ; Adib Nazari, Saeed (Supervisor)

Abstract

This research explored the corrosion effect of NaCl solution on the surface quality of AZ31 magnesium alloy. Cubic-shaped specimens were immersed in standard 3.5% NaCl solution for 1, 2, 3, and 4 hours. The size of corrosion pits, fatigue crack propagation area, and surface topology were characterized. Fatigue tests were carried out on pre-corroded AZ31 specimens under different stress amplitudes. The correlation between the corrosion time and the virtual crack size was obtained. The virtual crack size is a new parameter that can relate the corrosion to the fatigue life. A new model was proposed to map the surface topology on the virtual crack size of pre-corroded AZ31 magnesium alloy. The...

Simulating Sediment Transportation (Scour) Under Pipelines

, M.Sc. Thesis Sharif University of Technology Mokhtari, Hossein (Author) ; Abbaspour, Madjid (Supervisor)

Abstract

Regarding to significant role of marine pipelines in transferring oil, water and other products, a research was carried out to study the sediment transportation (Scouring) under pipelines which threaten pipelines. Interaction between fluid phase (flow field), structure phase (pipe) and sediment, determine scour profile shape and specifications of each phase which can change scour depth. In this research Flow-3D software was used to simulate scouring process under cylinder. First the flow field around cylinder near wall was studied and the scour depth under direct and oscillating flow was simulated. In addition, in next pace, the number of pipes and their distance were varied to measure...

Investigation on Hydrodynamic Locomotion of Sea Turtle

, M.Sc. Thesis Sharif University of Technology Jokar, Mohammad (Author) ; Abbaspour, Madjid (Supervisor)

Abstract

Nowadays, underwater vehicles designed by getting inspiration from aquatic animals’ motions have considerable merits; therefore, the issue of designing and building such vehicles has great significance. One of the aquatic animals, which can be a source of inspiration for designing vehicles with optimized propulsion and maneuver ability, is turtle. In order to design a robot under the inspiration of turtle locomotion, at first, it requires analyzing its locomotion carefully. In this project, it has been tried to do so. Having examined the motions of turtles and other aquatic animals thoroughly, the basics of their motions are achieved. Next, the locomotion of both sea and pond turtle are...

Design and Development of a Software for Analyzing Hydrodynamic Behavior of Spm System

, M.Sc. Thesis Sharif University of Technology Tahmasvand, Hossein (Author) ; Abbaspour, Madjid (Supervisor)

Abstract

In recent decades, SPM system has become a great method for transferring petroleum products to tankers and vice versa. SPM technology has shown his confidence and operation abilities. Sea waves are the most important phenomenon to be considered in the design of coastal and offshore structures. In this study dynamic motion of SPM floating structure is modeled under sea waves loading. Mooring lines connected to structure is modeled by using static stability equations and equivalent stiffness matrix is computed. First the SPM floating structure motion is modeled in 2 dimension (3 degree of freedom) using the boundary element method in frequency domain under regular sea waves loading and the...

Evaluation of the Hydrodynamic Performance of A Special Submarine Rescue System

, M.Sc. Thesis Sharif University of Technology Mohammadpour, Mojtaba (Author) ; Abbaspour, Madjid (Supervisor)

Abstract

The increasing growth of marine tourism has strengthened the activities related to this industry. One of the most profitable of these activities is recreational submarines. A traction recreational submarine is an idea in this field, in order to reduce costs, the propulsion force is removed and the submarine is towed by the mother ship. The most important reason for using the traction system and removing the independent drive is to prevent vibration and noise caused by the rotation of the propeller to prevent the escape of aquatic animals and to create a beautiful view from under the sea to watch underwater wonders. Searching for safety and saving people's lives in emergency situations is an...

Design and Simulation of a Towed Underwater Vehicle

, M.Sc. Thesis Sharif University of Technology Borhani, Hamed (Author) ; Abbaspour, Madjid (Supervisor)

Abstract

Nowadays marine-tourism industry, especially under water tourism, has become very attractive. Thus, numerous under water vehicles are designed and constructed. The primary objective of the present study is to design an underwater vehicle capable of carrying ten passengers. Tow system is proposed as propulsion system. Due to the high costs, noise and vibrations of existing propulsion systems in medium size vehicles which contradicts the goal of calm atmosphere for passenger, the proposing system seems suitable and pragmatic. Two-part tow system is utilized to enhance the stability of the under water vehicle named Towfish. In this study the structure of towfish is being designed. Then,...

Parallel machine scheduling problem with preemptive jobs and transportation delay

, Article Computers and Operations Research ; Vol. 50, issue , Oct , 2014 , p. 14-23 Shams, H ; Salmasi, N ; Sharif University of Technology

2014

Abstract

In this research the parallel machine scheduling problem with preemption by considering a constant transportation delay for migrated jobs and minimization of makespan as the criterion i.e., Pm|pmtn(delay)|Cmax is investigated. It is assumed that when a preempted job resumes on another machine, it is required a delay between the processing time of the job on these two machines. This delay is called transportation delay. We criticize an existing mathematical model for the research problem in the literature [Boudhar M, Haned A. Preemptive scheduling in the presence of transportation times. Computers & Operations Research 2009; 36(8):2387-93]. Then, we prove that there exists an optimal schedule...

Experimental study of two-phase oil – Polymer flow in horizontal flow path

, Article Experimental Thermal and Fluid Science ; Volume 100 , 2019 , Pages 62-75 ; 08941777 (ISSN) Shams, R ; Shad, S ; Sharif University of Technology

Elsevier Inc 2019

Abstract

Two-phase flow inside the oil and gas wells and flow path lines is a usual occurrence in petroleum and petrochemical studies. Due to its complexity, flow transfer parameters such as hold up and pressure drop and their dependency on the flow regime maps are not well understood yet. This study is aimed at analyzing holdup for oil- water system and evaluation of this parameter by means of Image processing under different available flow regime conditions. In addition, different oil-polymer systems have been studied to evaluate the impact of polymer concentration on transport criteria. The experimental setup used for this study is consisted of a 12 m long Plexiglas pipe with an inner diameter of...

Experimental study of two-phase oil – Polymer flow in horizontal flow path

, Article Experimental Thermal and Fluid Science ; Volume 100 , 2019 , Pages 62-75 ; 08941777 (ISSN) Shams, R ; Shad, S ; Sharif University of Technology

Elsevier Inc 2019

Abstract

Two-phase flow inside the oil and gas wells and flow path lines is a usual occurrence in petroleum and petrochemical studies. Due to its complexity, flow transfer parameters such as hold up and pressure drop and their dependency on the flow regime maps are not well understood yet. This study is aimed at analyzing holdup for oil- water system and evaluation of this parameter by means of Image processing under different available flow regime conditions. In addition, different oil-polymer systems have been studied to evaluate the impact of polymer concentration on transport criteria. The experimental setup used for this study is consisted of a 12 m long Plexiglas pipe with an inner diameter of...

Seismic Design of Substation Structures with Consideration of IEEE-693

, M.Sc. Thesis Sharif University of Technology Shams, Mohammad (Author) ; Mofid, Massoud (Supervisor)

Abstract

The Reliability of substation structures with consideration of earthquake uncertainties is one of the most important subjects in structural analysis in recent years. In this project we first introduce IEEE-693-2005, which is the most effective and comprehensive seismic design code for electronic substations. Also in second chapter the rudimentary aspects of Reliability Theory and methods for evaluating the reliability of substation structures is introduced. Then with modeling the most common and most important electronic substation devices in Iran, with consideration of all seismic parameters and their uncertainties, the reliability of these structures evaluated. In this project for...

Scheduling on Parallel Machines with Preemption and Transportation Delays using a Particle Swarm Optimization (PSO)-Based Algorithm

, M.Sc. Thesis Sharif University of Technology Shams, Hesam (Author) ; Shadrokh, Shahram (Supervisor)

Abstract

This research deals with the problem of scheduling independent preemptive jobs on identical parallel machines, to minimize the total completion time (makespan). The transportation of an interrupted job from a machine to another machine requires considering a constant transportation delay i.e., Pm|prmp(delay)| Cmax. This delay is called transportation delay. We propose a Mixed Integer Linear Programming formulation for the research problem in case of two machines i.e., P2|prmp(delay)| Cmax. Since the research problem is shown to be NP-hard, a particle swarm optimization (PSO) algorithm is applied to solve the problem approximately. Based on the frequency of using local search procedure, three...

Speaker Adaptation in Eigen Voice Space for Statistical Parametric Speech Syntheis

, M.Sc. Thesis Sharif University of Technology Shams, Boshra (Author) ; Sameti, Hossein (Supervisor)

Abstract

Recently various speaker adaptation methods in HMM-based speech synthesis are proposed. The importance of adaptation techniques is that we can design a system in which speech is generated with high quality and target speaker characteristics through limited adaptation data sets.
In this research, we focus on adaptation based on clustering and develop a new and novel method using eigenvoices in order to adapt a new speaker. We employ this approach for the first time in HSMM-based speech synthesis systems and its goal is to reduce the parameters and adaptation data of the system. In our proposed method, first some speaker dependent models are trained. For each model we combine the...

A Simulation for Better Understanding of Integrin Clustering and Activation

, M.Sc. Thesis Sharif University of Technology Shams, Shahab (Author) ; Motahhari, Abolfazl (Supervisor)

Abstract

Today, computer simulations are employed prevalently by researchers to understand biological processes. The tendency to use computational methods has been increased recently due to the high costs and errors of experimental methods. Integrins are membrane proteins that mechanically attach cells to the extra cellular matrix (ECM) and derive some behaviors such as cell migration. Moreover, integrins have biochemical functions. They transduce environment signals and trigger chemical pathways. As a result, integrins regulate cell shape, motility, etc. The investigation of integrin behavior in a real environment is very difficult due to the presence of many other proteins that interfere with the...

, M.Sc. Thesis Sharif University of Technology Ounaghi, Mohammad Safa (Author) ; Abbaspour, Madjid (Supervisor)

Abstract

In order to design a ship with waterjet system, estimation of its hydrodynamic performance is crucial. Presence and operation of waterjet propulsion system changes the flow field and pressure distribution in bottom and stem of ship hull, so affect hydrodynamic performance of craft. In the present thesis, CFD analysis is applied to free surface flow around a waterjet propelled ship using ANSYS CFX software. Also a waterjet propulsion system is built and settled in a ship model and resistance and self propulsion tests are performed. In order to performing a systematic process in project, in the first step, pump design is performed with extracting optimum efficiency relations and cavitation...

Experimental investigation of two phase flow in horizontal wells: Flow regime assessment and pressure drop analysis

, Article Experimental Thermal and Fluid Science ; Volume 88 , 2017 , Pages 55-64 ; 08941777 (ISSN) Shams, R ; Tavakoli, A ; Shad, S ; Sharif University of Technology

Elsevier Inc 2017

Abstract

Multiphase flow is fundamental to different fields of engineering and science including petroleum engineering. In oil and gas, flow of multiple phases inside wells is a common phenomenon. In such conditions, petroleum engineers deal with different design and operational difficulties due to complexities involved in flow of multiple phases inside a well. Unlike flow of gas and liquid inside a well, the liquid-liquid flow inside a horizontal well has received rather less attention. This study is aimed at experimentally investigating multiphase flow in a horizontal well by using a 12 m length and 30 mm diameter well made of Plexiglas. Despite the importance of defining pattern transition...

Holistic change management: importance and methodological challenges

, Article 2017 IEEE Technology and Engineering Management Society Conference, TEMSCON 2017, 8 June 2017 through 10 June 2017 ; 2017 , Pages 272-276 ; 9781509011148 (ISBN) Shams, A ; Sharif, H ; Kermanshah, A ; Sharif University of Technology

2017

Abstract

various researchers and practitioners have identified a range of problems and deficiencies with existing change-related frameworks, while each framework can include unique valuable elements in its people/process/technology aspects and theoretical foundations. In such a setting, we have adopted a holistic approach through examining an armada of existing frameworks and methodologies. Several decades of combined intercontinental experience of the authors (and much more from their academic/practice network) in the field of change management is culminating in development of a novel overarching framework referred to as Total Change Management (TCM). In the three years course of establishment of...

Assessing the effect of inattention-related error and anger in driving on road accidents among Iranian heavy vehicle drivers

, Article IATSS Research ; 2020 Shams, Z ; Naderi, H ; Nassiri, H ; Sharif University of Technology

Elsevier B.V 2020

Abstract

Extensive studies have examined the effect of variables such as demographic characteristics, insomnia, and working conditions of drivers individually on inattention-related error as well as expression of anger in driving. Nevertheless, so far no study has tested the concurrent effect of these factors on crashes. This study has dealt with indirect investigation of the effect of variables including demographic characteristics, insomnia, and working conditions of drivers on inattention-related error and expression of anger in driving (as mediation model). Next, the effect of these two variables on the probability of incidence of road crashes has been assessed among truck drivers. For this...

Assessing the effect of inattention-related error and anger in driving on road accidents among Iranian heavy vehicle drivers

, Article IATSS Research ; Volume 45, Issue 2 , 2021 , Pages 210-217 ; 03861112 (ISSN) Shams, Z ; Naderi, H ; Nassiri, H ; Sharif University of Technology

Elsevier B.V 2021

Abstract

Extensive studies have examined the effect of variables such as demographic characteristics, insomnia, and working conditions of drivers individually on inattention-related error as well as expression of anger in driving. Nevertheless, so far no study has tested the concurrent effect of these factors on crashes. This study has dealt with indirect investigation of the effect of variables including demographic characteristics, insomnia, and working conditions of drivers on inattention-related error and expression of anger in driving (as mediation model). Next, the effect of these two variables on the probability of incidence of road crashes has been assessed among truck drivers. For this...

Conformational Substates of Wild Type and Mutant (V68N) Myoglobin-CO

, M.Sc. Thesis Sharif University of Technology Shams, Hengameh (Author) ; Ejtehadi, Mohammad Reza (Supervisor)

Abstract

Folded protein experience several conformational substates. Each substate reperesents a minimum in the free energy surface of the system. Since Myoglobin is the smallest protein that can reversibly bind to gas molecules and, it can be used as prototype for more complex systems.IR pecrtum of CO inside of myolgobin shows that distinct conformational substates can occur. It was shown that Histidine residue inside heme pocket plays an essential rolle in structural properties of substates. In this study, we used molecular dynamice simulation together with umbrella sampling method to obtain free energy profile of MbCO system. The configuration of distal Histidine (His64), CO and Heme is studied...

Numerical Study of Nonlinear Ship Rolling and Anti-Roll Tank Effect

, M.Sc. Thesis Sharif University of Technology Shams, Shahab (Author) ; Saif, Mohammad Saeed (Supervisor)

Abstract

This thesis investigates nonlinear rolling of ships and effect of anti-rolling tanks. For this purpose numerical method is used. For studying this phenomenon, a program was developed in Simulink module of commercial software, MATLAB and roll motion has been simulated. The program has been developed so it can be used for displacement commercial vessels with a typical hull form and the simulated tank is a U-shape type tank. Simulation is 1-DOF and for rolling in regular waves with different encounter angel except for head sea and following sea. Results are included of roll degree, angular velocity and acceleration of ship and tanks fluid roll, encounter wave moment on ship and moment imposed...