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    Development of Finite Volume Method for Coupled Radiative, Convective, and Conductive Heat Transfer in Participating Media

    , Ph.D. Dissertation Sharif University of Technology Abrar, Bagher (Author) ; Darbandi, Masoud (Supervisor)
    Abstract
    Numerical simulations of participating media need careful solution of the radiation transfer equation (RTE) along the fluid flow governing equations. Evidently, the accuracy of achieved solutions highly depends on the accuracy of radiation transfer calculations. Despite numerous efforts performed in the previous researches, the RTE calculation still faces with several challenges from both accuracy and computational cost perspectives. The main objective of this research is to present new contributions in overcoming such challenges. So, a finite-volume (FV) solver is suitably developed to solve the RTE numerically. This extended solver is then coupled with an existing FV flow solver. The... 

    Electrophoretic Deposition of Graphene Oxide Nanocomposite on Magnesium substrate Modified by PEO

    , M.Sc. Thesis Sharif University of Technology Abrar, Bahareh (Author) ; Ghorbani, Mohammad (Supervisor)
    Abstract
    Plasma electrolyte oxidation process is one of the surface coating methods which is recommended to use as a surface preparation before applying the final coating on magnesium alloys due to its unique properties such as excellent adhesion.The aim of this study was to create an oxide layer on the AZ91 substrate and after optimizing the PEO coating conditions and choosing the best coating in order to increase adhesion and corrosion resistance, the composite coating of graphene oxide, hydroxyapatite and chitosan was applied by electrophoretic method. After studying the morphology of PEO oxide coating at current densities of 0.25, 0.35, 0.4, 0.5 and 0.6 amp/cm2 during times of 5 and 8 minutes, it... 

    CFD simulation of natural draught cooling tower wind-covering

    , Article Applied Mechanics and Materials, Dubai ; Volume 307 , 2013 , Pages 279-284 ; 16609336 (ISSN) ; 9783037856598 (ISBN) Darbandi, M ; Salemkar, H ; Behrouzifar, A ; Abrar, B ; Sharif University of Technology
    2013
    Abstract
    Past experiences have shown that a local wind can considerably affect the performances of powerplant cooling towers and factory chimneys. In thermal powerplants, the performance of Rankin cycles would reduce if the temperature of its condenser increases. This issue is very important to powerplants located in countries with strong local winds. To remedy the malperformance of a natural cooling tower in windy conditions, it is required to understand the physics of flow around cooling towers more clearly. One adverse physics is known as the wind covering problem which can drastically affect the natural draught through a cooling tower in windy conditions. In this paper, we focus on wind-covering... 

    A novel approach to design of a power factor correction and total harmonic distortion reduction-based BLDC motor drive

    , Article Frontiers in Energy Research ; Volume 10 , 2023 ; 2296598X (ISSN) Bin, L ; Abdeen, Z. U ; Abrar, M ; Abdul Muqeet, H ; Shahzad, M ; Zulfiqar, M ; Hussain, M. M ; Sharif University of Technology
    Frontiers Media S.A  2023
    Abstract
    This study describes a novel approach to design of a power factor correction (PFC) and total harmonic distortion (THD) reduction-based brushless DC (BLDC) motor drive. The drive was designed to obtain a reduced THD for PFC. The basic design of the BLDC motor drive contains an AC voltage source as input for a diode bridge rectifier. The output DC voltage is filtered out to reduce ripples. The smooth DC output voltage is supplied to the modified Zeta converter. The output voltage of the modified Zeta converter is controlled by using pulse width modulation (PWM). The modified Zeta converter is utilized in discontinuous inductor current mode (DICM) for better power factor. This controlled DC... 

    Analyzing Airport Saturation Based on Continuous Descent Approach

    , M.Sc. Thesis Sharif University of Technology Norouzi, Ramin (Author) ; Malaek, Mohamad Bagher (Supervisor)
    Abstract
    Airport saturation is one of the important issues which have always been of the specialists’ concern. One of the major applications of this subject is at the airport approach problems. While using current conventional approach procedures have many disadvantages regarding high fuel consumption and subsequent much environmental and noise pollution, the CDA concept which is one of the modern topics introduced in consequence of free flight theory, has less such disadvantages compared to conventional approach. Subject of this study is to investigate whether Procedural approach or CDA saturates an aiport sooner if the traffic flow increases. In this dissertation, using BADA database, CDA... 

    Decision Matrix for a Safe Aerial Launch Release Mechanism

    , M.Sc. Thesis Sharif University of Technology Salmani, Hamed (Author) ; Malaek, Mohammad Bagher (Supervisor)
    Abstract
    The case of rapid small satellite aerial launch by mother airplane has various applications; such as space experiment, weather monitoring, and getting information from the earth monitoring during natural disasters. In this method, the satellite and the launch vehicle will be carried up by mother airplane to the definite height; then, the launch vehicle will be released and flied - to the insert of satellite into the desired orbit. Aerial launch system success depends on a set of complex elements and their interactions. In the present study, first of all, the element interactions will be investigated by system engineering approach based on operational scenarios; then, a new approach for... 

    Simulation and Analysis of the Coolant Mixing Test within the Reactor Pressure Vessel of BNPP Using ANSYS CFX 18.0

    , M.Sc. Thesis Sharif University of Technology Khalvandi, Mohammad (Author) ; Ghofrani, Mohammad Bagher (Supervisor)
    Abstract
    Various factors, such as increasing or decreasing the heat removal from the initial circuit, or increasing the flow rate of the cooling fluid in the reactor, causes the phenomenon of the coolant mixing in the PWR reactors. In this project, the thermohydraulic test of coolant mixing has been simulated in the pressure vessel of the Bushehr nuclear reactor. In this test, the mixing of the coolant caused by the reduction of heat removal from the primary circuit by the secondary circuit is investigated. In this case, the primary circuit temperature increases in the loop where the heat removal is reduced. The most important consequence of this event is the reactivity changes at the core of the... 

    TCAS Logic Improvement for Airliners Formation Flights

    , M.Sc. Thesis Sharif University of Technology Dolatabadi, Shirin (Author) ; Malaek, Mohammad Bagher (Supervisor)
    Abstract
    This study explores the trajectory optimization of two aircrafts’ formation flight seeking minimization of fuel consumption and flight duration while considering activation of the Traffic Collision Avoidance System (TCAS) during the flights. In order to model the effects of this system, a set of codes has been developed in the Matlab software environment, which utilizes an estimation model of induced drag for each aircraft by their relative positions. Also, position rotation is allowed, and the number and location of rotations are controllable by the user. The TCAS determines the allowable distances between aircrafts during flights based on relative velocities and relative heading angles.... 

    Simulation of Loop Connection of RCPs during Commissioning Test of BNPP Using RELAP 5 Code to Two or Three Operating Ones

    , M.Sc. Thesis Sharif University of Technology Zeynalian, MirHadi (Author) ; Ghofrani, Mohammad Bagher (Supervisor)
    Abstract
    In order to ensure the safety of the plants, a set of commissioning tests based on international standards for nuclear power plants is carried out before operation. In this research, one of the Bushehr power plant commissioning tests, the loop connection primary circuit cooling pump test, was simulated using the RELAP5 code. In this test, the effects of loop connection primary circuit pumps on the thermohydraulic parameters and the eneterance of test-related systems was evaluated. After simulating the systems related to the test and extracting the results of the stable state, were evaluated the transient results was obtained with the experimental results of the test of loop connection the... 

    Impact of leadership styles on employees’ performance with moderating role of positive psychological capital

    , Article Total Quality Management and Business Excellence ; Volume 32, Issue 9-10 , 2021 , Pages 1085-1105 ; 14783363 (ISSN) Ahmad Baig, S ; Iqbal, S ; Abrar, M ; Ahmad Baig, I ; Amjad, F ; Zia-ur-Rehman, M ; Awan, M. U ; Sharif University of Technology
    Routledge  2021
    Abstract
    The study aimed to investigate the most effective leadership style that enhances the employees’ performance at the workplace and also evaluate the impact of leadership styles (Laissez-faire leadership, Transformational leadership, Transactional leadership,) on employees’ performance in the textile sector of Pakistan. The study explored the moderating role of Positive psychological capital to examine the relationship between leadership styles and employee performance. A quantitative research technique was used, and Data were collected from the lower to middle-level manager of the textile sector. The findings of this study showed that laissez-faire leadership has a significant but negative... 

    "Aircraft Performance Enhancement via Mass Distribution Management"

    , M.Sc. Thesis Sharif University of Technology Zeyghami, Samane (Author) ; Malaek, Mohammad Bagher (Supervisor)
    Abstract
    This work describes a methodology to enhance aircraft performance via proper mass distribution management. The methodology aims to limit aircraft configuration in early stages of the design process to its desired performance. Mass Distribution Management (MDM), that is used in this work, is a new mathematical model which predicts the so-called aircraft Handling Qualities (HQ) via proper positioning of aircraft mass. This work shows how proper changes in B-747-100 fuel tanks arrangement can enhance its flight quality up to level one during its entire cruise flight without use of any stability augmentation systems. In general this work introduce a methodology to examine different fuel tanks... 

    Application of Error Potential in Brain-Computer Interface Systems

    , M.Sc. Thesis Sharif University of Technology Sakhavi, Siavash (Author) ; Shamsollahi, Mohammad Bagher (Supervisor)
    Abstract
    Brain computer interfaces (BCI) are systems designed to understand the brain function from activation patterns and dynamics recorded from the brain activity and use this knowledge to give disabled people the ability to communicate with their surroundings. Features are extracted from recorded signals from the brain while occupied in a mental task and classified into categories related to the task given. These classifiers are then used for the estimation of user anticipation. Usually, the tasks defined are meant to evoke or induce a potential in the pattern of the brain. Awareness of error responses is one of the cognitive functions of the brain which occurs when a response is in conflict with... 

    Airline Flight Schedule Planning with Network Optimization

    , M.Sc. Thesis Sharif University of Technology Rajabi, Hossein (Author) ; Malaek, Mohammad Bagher (Supervisor)
    Abstract
    Airline scheduling is a dynamic process in nature such that it changes not only during one year period but also in smaller intervals due to the economic, political, religious, and social factors. Basically, airlines schedule planners through using mathematical models decide which flights are to be served in what periods of time and at what costs. This has to be done considering a set of constraints of different nature, from airspace and airport congestion up to climatic conditions or even crews working conditions. Such a complex problem requires different methods for an efficient solution. In this study by using network optimization method and applying different operational constraints on... 

    Application of PSA Methods in the Reliability Analysis of EPSS of Busherhr NPP in case of Station Black Out

    , M.Sc. Thesis Sharif University of Technology Khorrami, Vahid (Author) ; Ghofrani, Mohammad Bagher (Supervisor)
    Abstract
    LOOP accident is one of the most important accidents in NPPS and it leads to loss of power supply of the RCP pumps which are the main pumps of primary circuit. Subsequently trip of the rector occurs. In safety analysis, concerning worst conditions, assumes that after a small period of time, main generator of plant stops working and loss of AC power supply of all power plant loads including safety systems ocures. To control of this accident, it’s necessary to startup and load backup power supply system (EDGs) for at least one safety channels, if not, the accident moves forwards and becomes S.B.O accident which is more important accident that ends to core damage because of stops working of all... 

    A Study of Induced Systems Behavioral

    , M.Sc. Thesis Sharif University of Technology Farhangi, Hadi (Author) ; Malaek, Mohammad Bagher (Supervisor)
    Abstract
    Towards basic-applied Research in the System Sciences fields, this Research has been to try to understand the behavior patterns and Functional Architecture of parasitic organisms and Use these in Social-Economic Systems. In this research four scenarios for parasite behavior were found and based on one of them, the recent "Financial Crisis in Greece" has been evaluated. The results show that the developed model, can be effective in similar conditions.
     

    Probabilistic Safety Assessment of A UF6 Production Process

    , M.Sc. Thesis Sharif University of Technology Ebrahimi, Behrooz (Author) ; Ghofrani, Mohammad Bagher (Supervisor)
    Abstract
    Identification of different hazards in a UF6 production process, and evaluation of the risk originated from these hazards is the main objective of this project. A number of hazards are present in a typical UF6 production process, such as leakage of chemical gases like HF and F2 and also radioactive UF6 gas release. In order to evaluate risk due to these hazards, probabilistic approach has been used. Due to lack of probabilistic safety criteria (PSC) for chemical releases, only for UF6 gas release risk assessment has been done. As a first step in PSA of this process eight groups of initiating events have been identified using HAZOP study, and for each initiating event, event tree analysis... 

    Application of Dynamic Sectorization in Air Traffic Controller Workload Balancing

    , M.Sc. Thesis Sharif University of Technology Farsad, Mahsa (Author) ; Malaek, Mohammad Bagher (Supervisor)
    Abstract
    In order to manage a complex system, one way is to divide it into smaller parts. That’s the reason airspace in each country should be divided into sectors. Currently, these sectors have fixed areas and each is controlled by a number of air traffic controllers. However, the traffic crossing these sectors is considerably dynamic, which means the traffic density and its distribution varies seasonally, weakly and even through the 24 hours of a day. Moreover, weather conditions and security and military issues make constraints to some of these sectors. This sometimes results in some high traffic sectors while some others have very low traffic density which causes two main problems. One is that,... 

    The Investigation of Sustainable Transportation System Characteristics

    , M.Sc. Thesis Sharif University of Technology Barati, Elaheh (Author) ; Malaek, Mohammad Bagher (Supervisor)
    Abstract
    This work, with the help of FUZZY DEMATEL and FUZZY TOPSIS methods investigates the behavior of a general transportation system. In fact, we have been able to develop a cause and effect model to describe why in an unsustainable system any increase in the so called “human value” would not help increase the overall system’s sustainability. Moreover, we have been able to analyze the new role of the key stakeholders as “insurance companies”. in fact, such companies receives a guaranteed flow of money without providing any extra services in the current unstable situation which help widen the gap and increase the rate of instabilities. Further investigations might be necessary to examine the role... 

    Flexibility Analysis in Supply Chain by Using Design Structure Matrix

    , M.Sc. Thesis Sharif University of Technology Yousefi, Zahra (Author) ; Malaek, Mohammad Bagher (Supervisor)
    Abstract
    Supply chains are socio-technical engineering systems which now days perform in more uncertain operational environment than before. These systems have been vulnerable because of increasing the number of natural disasters, competitiveness and changing the demand. So these systems in order to be survived in such high uncertain environment need to enhance some capabilities in their structure. In this research by considering an assumed auto supply chain, we try to develop an approach to cover uncertainties in operational environment of this system. At the next step, we use design structure matrix modeling to model the interactions between system elements before and after scenario occurring.... 

    Thermal Hydraulic Analysis of Prismatic Htgr with Natural Convection Using Porous Media Approach (in Case of Lose of Forced Circulation Accident)

    , M.Sc. Thesis Sharif University of Technology Golshanee, Masoud (Author) ; Ghofrani, Mohammad Bagher (Supervisor)
    Abstract
    In this study, the thermal-hydraulic analysis of prismatic HTGR’s core with natural convection has been studied using porous media approach. VHTR are the new generation reactors which due to special neutron and thermo physical properties have highly inherent safety. In lose of forced circulation accident, decay heat is transferred from core to pressure vessel wall and then to water tubes in concrete wall at reactor cavity with conduction, convection and radiation automatically. In this case the high volume of decay heat is stored in graphite block with high thermal capacity and is prevented the instantaneous temperature rising.
    The aim of this study is justifying inherent safety of HTGR...