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jamshid-doost--asghar
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Failure Modes Analysis and Mechanisms for Life Extension of Gas Turbines
, M.Sc. Thesis Sharif University of Technology ;
Abstract
Currently, the relatively long time of the turbine life passes and their parts and equipment damage are different, that loss optimum performance and thus reducing their efficiency and may lead to faults and other unexpected stops in their production cycle. Process used to estimate the remaining life of the various components of this turbine is an important tool for improving the efficiency of these units to perform preventive maintenance. In the present thesis, the types of damages in different parts of gas turbines and various methods for detection of critical points, particularly finite element method, high cycle fatigue, modal analysis, methods to estimate the lifetime of a gas turbine...
Seismic performance of precast RC column to steel beam connections with variable joint configurations
, Article Engineering Structures ; Volume 160 , April , 2018 , Pages 408-418 ; 01410296 (ISSN) ; Bakhtiari Doost, R ; Sharif University of Technology
Elsevier Ltd
2018
Abstract
In the last decades, noticeable experimental and analytical investigations have been carried out on cast-in-place Reinforced Concrete column to Steel beam (RCS) connections, however rarely have been conducted on the precast RCS. In this paper, test results of four half-scale interior precast RCS connections with variable joint configurations are presented. The steel beams were connected to the precast column, using three specimens with extended face bearing plates and one with extended cover plates, embedded in the connection zone. The flanges of beams were strengthened with respect to scaled section, in order to increase the load transfer to the joint. All samples were loaded under reversed...
Steel web panel influence on seismic behavior of proposed precast RCS connections
, Article Structures ; Volume 32 , 2021 , Pages 87-95 ; 23520124 (ISSN) ; Khaloo, A ; Sharif University of Technology
Elsevier Ltd
2021
Abstract
In this study, the experimental finding of two half-scale interior prefabricated Reinforced Concrete column to Steel beam (RCS) sub-assemblage with proposed joint formations with and without web panel in the junction is presented. Previous researches about RCS have been performed to study shear strength of steel web panel in the joint by modeling joint component, however rarely have been conducted to evaluate joint shear resistance experimentally. Over the past 30 years, noticeable analytical and experimental assessments have been performed on the cast in place RCS joints, but seldom have been done on the prefabricated RCS. The steel beams in the proposed joint are attached to the expanded...
Analysis and Optimization of Surge Control System of a Centrifugal Compressor
, M.Sc. Thesis Sharif University of Technology ; Mazaheri, Karim (Supervisor)
Abstract
The surge phenomenon, as the most important aerodynamic instability, has caused a severe drop in efficiency and performance in centrifugal compressors, and its prevention and control is considered one of the main concerns of industrialists. The purpose of this study is to design and develop a surge control system in order to improve the stability and safety of the system under the effect of surge. In this research, after simulating the existing control system and working line in Borzouyeh Petrochemical Industry, by designing and adding the piston surge active control system to the above centrifugal compressor and using the combined control system, the flow rate of the bypass path has been...
Seismic behavior of Moment Resisting Steel Beam-Precast Reinforced Concrete Column Connections
, Ph.D. Dissertation Sharif University of Technology ; Khaloo, Alireza (Supervisor)
Abstract
In the last decades, noticeable experimental and analytical investigations have been carried out on cast-in-place Reinforced Concrete column to Steel beam (RCS) connections, however rarely have been conducted on the precast RCS. In this reaserch, test results of five half-scale interior precast RCS connections with variable joint configurations are presented. The steel beams were connected to the precast column, using face bearing plates, embedded in the connection zone. The flanges of beams were strengthened with respect to scaled section, in order to increase the load transfer to the joint. All samples were loaded under reversed displacement controlled condition. The failure mode, joint...
Effects of Water Market Formation in the Basin of Lake Urmia
, M.Sc. Thesis Sharif University of Technology ; Vesal, Mohammad (Supervisor)
Abstract
Considering that the agricultural sector is the largest consumer of water in the basin of Lake Urmia, it seems necessary to provide comprehensive methods of water resources management and formulate appropriate policies to increase water productivity in this sector. For this reason, in this research, we examine the effects of creating a water market in the basin of Lake Urmia. For this purpose, models of agricultural economics and positive mathematical programming techniques at the regional level have been used for modeling to analyze the various effects of water market creation. According to the model, the farmer chooses his cultivation pattern according to the price of the crop and the...
Analytical Evaluation of Moment Resisting Precast Concrete Beam to Column Connections by Finite Element Method
, M.Sc. Thesis Sharif University of Technology ; Khalu, Alireza (Supervisor)
Abstract
In this thesis, the behavior of proposed moment resisting precast beam-column concrete connection under cyclic and monotonic loads is investigated. In this study, the finite element models of precast and monolithic middle and corner connections are created. The results of finite element analysis under cyclic loading is verified with existing experimental results based on failure mode, ductility, energy dissipation capacity and flexural strength. Based on the results of nonlinear finite element analysis, the analytical behavior of samples is in good agreement with experimental results and finite element analysis of proposed precast connection can be replaced with supplementary tests. Then the...
Experimental Investigation of Mud-Induced Formation Damage in Fractured Reservoirs
, M.Sc. Thesis Sharif University of Technology ; Rashtchian, Davood (Supervisor) ; Moghadasi, Jamshid (Supervisor)
Abstract
Productivity reduction of oil and gas wells due to mud induced permeability impairment is one of challenging problems in drilling and production studies. This phenomenon is of prime importance in fractured reservoirs in which high permeability fracture networks act as conduits for feeding gas or oil from a tight matrix to the wellbore. Up to now, many experimental and modeling investigations have been done in formation damage in conventional reservoirs. But in spite of large contribution of fractured reservoirs in total hydrocarbon reserves, there is very little work reported in the literature investigating formation damage in such reservoirs. In this thesis, the effective parameters in...
Comparison of Rheological Properties of Slurry with International Standards to Evaluate the Successfulness of Gachsaran Oil Field Cementation and Proposing Experimental Solutions
, M.Sc. Thesis Sharif University of Technology ; Ghotbi, Sirous (Supervisor) ; Moghadasi, Jamshid (Supervisor)
Abstract
The rheology of oil well cement (OWC) slurries is generally more complicated than that of conventional cement paste. In order to contend with bottom hole conditions, a number of additives are usually used in the OWC slurries. The objective of this research is to develop a fundamental understanding of the important mechanisms that affect the properties of OWC slurry such as rheological properties, free water, compressive strength and thickening time incorporating various chemical and mineral admixtures. The partial replacement of OWC using different nanoparticle weight percent has been proved to be a promising method. The mechanisms underlying the effects of chemical admixtures on the...
Preparation and Characterization of Chitosan-Gelatin/Polyanilne-Graphene-CNT Nanocomposite for Neural Tissue Engineering
, M.Sc. Thesis Sharif University of Technology ; Ramazani Saadatabadi, Ahmad (Supervisor)
Abstract
Repairing and regeneration of neural tissues have attracted considerable attention due to its direct effect on the quality of patients’ lives. Recent developments in nanotechnology and tissue engineering have facilitated their comprehensive applications in the treatment of neurological diseases, and several effective ways have been proposed to repair defects in neural tissues. The main objective of the researches in this field is to regulate cellular behavior and tissue progression through the design and development of synthetic extracellular matrices, such as novel biomaterials, that enhance cell culture and tissue regeneration. Natural polymers, such as chitosan and gelatin, are suitable...
Nonlinear finite element analysis and parametric study of executable RCS connections
, Article Archives of Civil and Mechanical Engineering ; Volume 22, Issue 4 , 2022 ; 16449665 (ISSN) ; Sadraie, H ; Khaloo, A ; Badarloo, B ; Sharif University of Technology
Springer Science and Business Media Deutschland GmbH
2022
Abstract
This paper compares the results of a nonlinear finite element analysis (FEA) of an internal hybrid steel beam to RC column connections with those of the experiment on a half-scale. This study used extended face bearing plates (EFBP) embedded in the panel zone (PZ) to make prefabricated RC column to steel beam connections (PRCS). Steel beam flanges were made to be stronger than scaled sections to transfer more force to the PZ. Nonlinear FEA was performed with ABAQUS software to evaluate the connections under unidirectional loading. Failure mode, connection stiffness, and PZ shear strength determined by nonlinear FEA matched well with the experimental findings. PRCS1 model was used to evaluate...
Design and Analysis of an E-voting System Based on Blockchain
, M.Sc. Thesis Sharif University of Technology ; Mohajeri, Javad (Supervisor) ; Salmasi Zadeh, Mahmoud (Co-Supervisor)
Abstract
Voting has been considered as one of the principal of democracy which by this, people can announce their convictions and ideas officially. E-voting is a method of online voting based on cryptographic mechanisms. E-voting schemes by keeping voters' privacy safe and providing security requirement same as verifiability, fairness, coercion resistance, receipt freeness, undeniability, and eligibility has been noticed in recent years. Security of many presenting schemes is based on existence of trusted third party that plays an important role in process of getting and counting votes. Also, some of security problems which are in this scheme, originated from centralization and generic trust of third...
Experimental Investigation of Factors Affecting Formation Damage through Aqueous Phase Trapping in Gas Reservoirs
, M.Sc. Thesis Sharif University of Technology ; Masihi, Mohsen (Supervisor) ; Moghadasi, Jamshid (Supervisor)
Abstract
Aqueous phase trapping (APT) in many of the oil and gas reservoirs is a significant mechanism of formation damage during drilling, completion, work over, and stimulation operation. APT can limit the productivity of the well to a high extent, especially in low permeable gas reservoirs. Experimental investigation of factors affecting APT is vital to recognize extends of associated damage and contribution of each factor. Albeit many experimental studies have been conducted as regards factors affecting removal of phase traps in understudy mechanism of formation damage, but up to date no experimental data has been published regarding effect of different factors on reservoir’s potential for APT....
Optimizing floor reservation and contention resolution in wireless random access
, Article Ad Hoc Networks ; Volume 82 , 2019 , Pages 31-45 ; 15708705 (ISSN) ; Golestani, S. J ; Doost Hoseini, A. M ; Sharif University of Technology
Elsevier B.V
2019
Abstract
In this paper, we propose a novel wireless random access scheme, combining the CSMA/CA mechanism with two control signals for initiating new transmissions and announcing receiver busy status, respectively. We also develop a time-space framework of performance analysis, enabling separate study of the temporal and spatial efficiency of the random access, i.e. the scheme's ability for contention resolution and efficient performance in time, and its ability to provide for concurrent transmissions in space. Based on this framework and using both analysis and simulation, we show that the proposed scheme outperforms the IEEE 802.11 DCF, in terms of the overall afforded throughput, and also in terms...
Experimental and Theoretical Investigation on Losses and One Dimensional Modeling of The Centrifugal Compressor
, M.Sc. Thesis Sharif University of Technology ; Hajilouy Benisi, Ali (Supervisor)
Abstract
Centrifugal compressors have wide applications in the turbochargers, aircraft propulsion and petrochemical industry. Therefore it is important to design high efficiency centrifugal compressor. Knowledge of compressor performance at different conditions, energy losses and the contribution of each component of compressor in efficiency losses have of great importance.
In this research, different loss models of the centrifugal compressor were reviewed and investigated. Then 1D codes were developed based on the loss models, and performance characteristics of S2B Schweitzer and GT4082 Garret compressors at different conditions were achieved. In order to evaluate the modeling results,...
In this research, different loss models of the centrifugal compressor were reviewed and investigated. Then 1D codes were developed based on the loss models, and performance characteristics of S2B Schweitzer and GT4082 Garret compressors at different conditions were achieved. In order to evaluate the modeling results,...
Provide a Location-Allocation Model for the Construction of Passenger ports in Mazandaran Province with the using of Robust Optimization Approach and Scenario Building
, M.Sc. Thesis Sharif University of Technology ; Akbari Jokar, Mohammad Reza (Supervisor)
Abstract
Iran has a huge potential in field of tourism and marine passenger transport with possessing 5780 K.M water coast including the island and access to rivers and water basins.Strategic decision of passenger ports construction needs careful location selection andfinding correct trade of point between cost of construction and operation cost. However, according to forecasts increasing cruises demand, creating appropriate port infrastructure to supply thesedemands is a big challenge in next years. Ignoranceof it will prevent the countries development and its communication with other countries.Infrastructure development and creation ofmarine transport modern networks is a pivotal key to satisfy...
Technical, Economic and Environmental Study and Evaluation of Urea and Ammonia Production Process
, M.Sc. Thesis Sharif University of Technology ; Farhadi, Fatollah (Supervisor) ; Vafa, Ehsan (Supervisor)
Abstract
process design and decision-making about it are challenging activities that involve optimizing conflicting goals such as cost, technical feasibility, and environmental impacts. These conflicting goals can be analyzed by considering the complete life cycle of a process or product in the initial design and decision-making. Life cycle analysis follows the environmental effects throughout the life cycle of a product, including extraction, transportation, production, consumption, and disposal. Life cycle assessment includes four fundamental stages: goal and scope definition, inventory analysis, life cycle impact assessment, and interpretation of results. The aim of this project is to investigate...
Analysis of Interlaminar Stresses in Boundary Layer of Circumferentially Closed Laminated Cylinders
,
M.Sc. Thesis
Sharif University of Technology
;
Noseir, Asghar
(Supervisor)
Abstract
In this study, using Reddy's layer-wise theory, thermal and rotational inter-laminar stress distribution within cylindrical composite shells with different boundary conditions is analytically studied. Convergence of the layer-wise theory is also studied and the numbers of sub-layers are determined so that efficient and accurate results can be achieved by this method. In order to assess the validity of layer-wise theory, results of this method are compared with results obtained by elasticity theory, for two sets of boundary conditions. It is observed that depending on the shell layer stacking, loading and boundary condition type, each of inter-laminar stresses may be the critical stress...
Hygrothermal Stress Analysis in Composite Laminatesby Perturbation Method
, M.Sc. Thesis Sharif University of Technology ; Nosier, Asghar (Supervisor)
Abstract
For studying the hygrothermal deformation of generally laminated composite platesunder uniform temperature change and uniform moisture absorption change, by starting from the reduced form of elasticity displacement field for a long flat laminate, an analytical method is developed in order to accurately calculate the interlaminar stresses near the free edges of the laminate. The constant parameters appearing in the reduced displacement field, describe the global deformation of the laminate and appropriately obtained by employing an improved first-order shear deformation theory.For solving the coupled equilibrium equations of agenerally laminated composite plate, some of the stiffness...
Nonlinear Forced Vibrations of Thin Circular and Elliptical Functionally Graded Plates
, M.Sc. Thesis Sharif University of Technology ; Nosier, Asghar (Supervisor)
Abstract
Nonlinear forced vibrations of thin functionally graded circular and elliptical plates under classical boundary conditions are investigated based on the classical plate theory. The von Kármán strain-displacement relations is employed to include geometrical nonlinearity caused by large transverse displacements of the plate thickness order, and modal expansion in polar and elliptical coordinate along with the perturbation method of multiple scale is used to solve the governing equations. The material properties are graded through the plate thickness according to a power-law distribution of the volume fraction of the constituents. Transverse forcing is supposed to be harmonic with angular...