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    Magnetic attitude control using fuzzy logic

    , Article Proceedings of the IEEE International Conference on Control Applications, 8 July 2009 through 10 July 2009 ; 2009 , Pages 456-460 ; 9781424446025 (ISBN) Heydari, A ; Pourtakdoust, S. H ; Heydari, H ; Sharif University of Technology
    2009
    Abstract
    A fuzzy controller has been suggested for attitude control of magnetic actuated satellites in order to calculate the desired mechanical torque based on the attitude error including error in the angles and their rates. The problem of selecting proper magnetic dipole based on the known desired mechanical torque has been investigated, two different methods for the purpose has been suggested and the performance of the attained fuzzy magnetic attitude controllers has been shown under two different simulated conditions. © 2009 IEEE  

    A Process Mining Approach to Analyze Customer Journeys to Improve Customer Experience

    , M.Sc. Thesis Sharif University of Technology Akhavan, Fatemeh (Author) ; Hassannayebi, Erfan (Supervisor)
    Abstract
    With the growth of the number of online service providers and the need to innovate in these services, in this study, the processes and the journeys taken by visitors of a website that provides employment services and employment insurance has been analyzed. In this research, process mining techniques and predictive process monitoring were implemented. With the use of a supervised and unsupervised learning algorithm, it attempted to identify the customer journeys' output and the existing patterns that lead to the complaint. In the first step, the website event log is extracted. Afterward, by using frequency-based encoding methods, the journeys traveled by users were clustered based on the... 

    Predictive Business Process Monitoring Using Machine Learning Algorithms

    , M.Sc. Thesis Sharif University of Technology Feiz, Roya (Author) ; Hassannayebi, Erfan (Supervisor)
    Abstract
    In order to survive in today's business world, which is changing at a very fast pace, organizations can detect deviations even before they occur, quickly and with a high percentage of confidence, by analyzing their processes, in order to prevent disruptions in the processes. by monitoring the information systems that automatically execute business processes, it is possible to ensure the correct implementation of the existing processes. For this purpose, various techniques for monitoring business processes have been presented so that managers have a comprehensive and real view of how implement processes and be able to identify possible deviations in the future and try to fix them because the... 

    Data-Driven Prediction for Monitoring Business Process Pperformances Based on Classification Algorithms

    , M.Sc. Thesis Sharif University of Technology Taheriyan, Zahra (Author) ; Hassannayebi, Erfan (Supervisor)
    Abstract
    In recent years, several studies have been conducted in the field of data mining techniques in the field of process mining with the aim of improving the performance of organizations. Predictive process monitoring is a data-driven approach that helps business managers to improve the status and conditions of their organization. In this approach, the event log, which includes a set of completed examples of a process, is received as input, and machine learning methods are used to predict the outcome and results of the organization's processes before the process is completed. This prediction can include the prediction of the final result, the next event, the time remaining until the completion of... 

    Operations Optimization in Supply Chain Systems using Simulation and Reinforcement Learning

    , M.Sc. Thesis Sharif University of Technology Mahmoudi, Farzaneh (Author) ; Hassan Nayebi, Erfan (Supervisor)
    Abstract
    The inventory costs constitute a significant portion of the supply chain costs. Therefore, choosing an optimal inventory policy for orders is of great importance. The aim of this research is to find the optimal inventory policy for a distribution center in a three-tier supply chain consisting of a manufacturer, a distribution center, and a retailer. This research simulates a supply chain in agent-based framework and optimizes it using reinforcement learning. The optimization KPI in this research is the mean daily cost of the supply chain. Finally, the result obtained from reinforcement learning is compared with the optimized result of AnyLogic and the mean daily cost in the model optimized... 

    Predictive Process Monitoring Based on Optimized Deep Learning Methods

    , M.Sc. Thesis Sharif University of Technology Alibakhshi, Alireza (Author) ; Hassannayebi, Erfan (Supervisor)
    Abstract
    Business processes are an essential part of every business as they provide insights on how to optimize and make them more efficient. Predictive Business Process Monitoring has garnered significant attention in recent years due to its capability to forecast process outcomes and predict the next activity within an ongoing process. In the last few years, there have been works that focused on deep learning and its applications in predicting the next activity. Some research used Long Term Short Memory, while others used Convolutional Neural Networks. However, long term short term memory models have the constraint of relatively slow training, while Convolutional Neural Networks are fast but may... 

    Customer Journey Analytics using Process Mining Based on the Markov Model

    , M.Sc. Thesis Sharif University of Technology Torabi Ardekani, Saba (Author) ; Hassan Nayebi, Erfan (Supervisor)
    Abstract
    The analysis of customer journeys has gained significant attention due to the critical role of customer behavior data in enhancing business decision-making and formulating strategies for customer acquisition and retention. By segmenting customers based on their journey patterns, businesses can offer personalized recommendations, thereby improving customer engagement and loyalty. Additionally, predicting the next steps in a customer’s journey based on historical data allows for timely and appropriate interventions at various touchpoints. By understanding where customers are in their journey, businesses can provide targeted recommendations that increase the likelihood of converting potential... 

    A System Dynamic Simulation Approach to Investigate Economic And Environment Factors Based on VUCA framework: A Case Study in Petrochemical Industry

    , M.Sc. Thesis Sharif University of Technology Monfaredi Jafarbagi, Aoun (Author) ; Hassannayebi, Erfan (Supervisor)
    Abstract
    To maintain adaptability, businesses should anticipate changes in their environment. The commonly employed forecasting method within corporate circles is the bottom-up approach, which relies on historical data for projecting future trends. However, research suggests that this approach often falls short of accurately reflecting real-world events. This has led to the adoption of dynamic systems modeling, a technique grounded in the assumption of stable conditions. This method effectively replicates the system's current state, thereby assisting in predicting future behaviors over a longer timeframe. The dynamic systems modeling approach was employed in this study, underscoring the imperative... 

    Discovering and Improving the Processes of an Iranian Psychiatric Hospital Using Process Mining

    , M.Sc. Thesis Sharif University of Technology Roshan, Mohammad Amin (Author) ; Hassan Nayebi, Erfan (Supervisor)
    Abstract
    Providing quality hospital services depends on the efficient and correct implementation of processes. Therapeutic care processes are a set of activities that are carried out with the aim of diagnosing, treating and preventing any disease in order to improve and promote the patient's health. The purpose of this study is to use process mining techniques to discover and improve healthcare processes. The case study of this research is a psychiatric hospital in Shiraz. The approach implemented in this research consists of three main stages including data pre-processing, model discovery phase, and analysis phase. Three algorithms including Heuristic Miner, Inductive Miner, and ILP Miner were used... 

    The investigation of natural super-cavitation flow behind three-dimensional cavitators: Full cavitation model

    , Article Applied Mathematical Modelling ; Volume 45 , 2016 , Pages 165-178 ; 0307904X (ISSN) Kadivar, E ; Kadivar, Erfan ; Javadi, K ; Javadpour, S. M ; Sharif University of Technology
    Elsevier Inc  2016
    Abstract
    In this study, natural super-cavitating flow around three different conical cavitators with wedge angles of 30°, 45° and 60° is investigated. We apply the k−ϵ turbulence model and the volume of fluid (VOF) technique to numerically study the three-dimensional cavitating flow around the cavitators. The turbulence approach is coupled with a mass transfer model which is implemented into the finite-volume package. Simulations are performed for different cavitation numbers. Finally, the effects of some important parameters such as the cavitation index, inlet velocity, Froude number and wedge angle of cavitators on the geometrical characteristics of the super-cavities are discussed. Our numerical... 

    Analysis and Improvement of Agile Software Development Process Using Process Mining and Machine Learning Algorithms

    , M.Sc. Thesis Sharif University of Technology Fardipour Asl, Mohsen (Author) ; Hassan Nayebi, Erfan (Supervisor)
    Abstract
    In the competitive world of software development, IT product development teams face numerous challenges and issues within business processes. In recent years, the combination of process mining and machine learning algorithms to optimize software development processes has gained attention. However, there is still a lack of a comprehensive model for identifying and conducting root-cause analysis of problems and providing solutions based on them in agile software development systems. The aim of this research is to find a solution for identifying and addressing issues in the software development process by modifying the change request workflow and examining various aspects of incidents. To... 

    Improve Performance of Process Mining Algorithms in Low-Level Event Log with Machine Learning Methods

    , M.Sc. Thesis Sharif University of Technology Choopannezhad, Mahsa (Author) ; Hassan Nayebi, Erfan (Supervisor)
    Abstract
    This thesis abstract addresses the use of process mining techniques when event data is stored at varying levels of granularity. While most techniques assume that events have the same level of granularity, real data is often stored differently. Pre-processing techniques allow for appropriate summarization of the data, which simplifies the output while retaining important process details. The goal is to ensure an interpretable output for stakeholders and different business teams without losing critical process points. However, adding new data as a feature to the dataset can be expensive, and at times, infeasible. Therefore, existing data is the only solution. To overcome this challenge, this... 

    An ellipsoidal model for studying response of head impacts

    , Article Acta of Bioengineering and Biomechanics ; Volume 12, Issue 1 , 2010 , Pages 47-53 ; 1509409X (ISSN) Heydari, M ; Jani, S ; Sharif University of Technology
    2010
    Abstract
    The objective of this study was to propose a new analytical model for studying response of head impacts. Head is modeled by fluidfilled ellipsoidal shell of inconstant thickness impacted by a solid elastic sphere. Modeling the head as an ellipsoid is more realistic than modeling it as a sphere, the previous model existing in the literature [3]-[8]. In this model, the effect of Hertzian contact stiffness and local shell stiffness are combined to derive explicit equations for impact duration, the peak force transmitted to head, and the head injury criterion. One of the advantages of the model presented is sensitivity to the site of impact. A comparison between the present analytical results... 

    Prediction of temperature distribution and volume of lesion during HIFU therapy

    , Article ITNG 2009 - 6th International Conference on Information Technology: New Generations, 27 April 2009 through 29 April 2009, Las Vegas, NV ; 2009 , Pages 1468-1473 ; 9780769535968 (ISBN) Heydari, M ; Jahed, M ; Sharif University of Technology
    2009
    Abstract
    Ultrasound hyperthermia is used to treat tumors in human tissue by heat. It is characterized by the application of high intensity focused ultrasound (HIFU), high local temperatures and short treating time of a few seconds. HIFU is a non-invasive treatment modality for a variety of cancers, including breast, prostate, kidney, liver, bone, uterus, and pancreatic cancers. Computer models have been used to determine tissue temperatures during ultrasound hyperthermia. In this work, we consider a liver tissue with a tumor at its center. We calculated temperature distribution in the presence a large blood vessel. We studied the effect of varying the exposure time (heating duration) and the diameter... 

    Theoretical modeling and optimizing design of a packaged liquid chiller

    , Article 2007 ASME/JSME Thermal Engineering Summer Heat Transfer Conference, HT 2007, Vancouver, BC, 8 July 2007 through 12 July 2007 ; July , 2007 , Pages 527-537 ; 0791842746 (ISBN); 9780791842744 (ISBN) Heydari, A ; Kargar, S ; Sharif University of Technology
    2007
    Abstract
    This work attempts to develop a physical simulation model for the purpose of studying the effect of various design parameters on the performance of a packaged liquid chiller. A computer model which simulates the steady-state cyclic performance of a vapor compression chiller is developed for the purpose of performing detailed physical design analysis of actual industrial chillers. The model can be used for optimizing design and for detailed energy efficiency analysis of packaged liquid chillers. The simulation model takes into account presence of all chiller components such as compressor, shell-and-tube condenser and evaporator heat exchangers, thermostatic expansion valve and connection... 

    Analysis and optimized design of a packaged liquid chiller (part I -Analytical modelling)

    , Article 2005 ASME Summer Heat Transfer Conference, HT 2005, San Francisco, CA, 17 July 2005 through 22 July 2005 ; Volume 4 , 2005 , Pages 461-466 ; 0791847314 (ISBN); 9780791847312 (ISBN) Heydari, A ; Kargar, S ; Sharif University of Technology
    2005
    Abstract
    The purpose of this work is to develop a physical simulation model for the purpose of studying the effect of various design parameters on the performance of a packaged liquid chiller. A computer model which simulates the steady-state cyclic performance of a vapor compression chiller is developed for the purpose of performing detailed physical design analysis of actual industrial chillers. The model can be used for optimizing design and for detailed energy efficiency analysis of packaged liquid chillers. The simulation model takes into account presence of all chiller components such as compressor, shell-and-tube condenser and evaporator heat exchangers, thermostatic expansion valve and... 

    A novel analytical model for a circularly-polarized, ferrite-based slot antenna by solving an integral equation for the electric field on the circular slot

    , Article Waves in Random and Complex Media ; Volume 32, Issue 2 , 2022 , Pages 509-528 ; 17455030 (ISSN) Heydari, M.B ; Ahmadvand, A ; Sharif University of Technology
    Taylor and Francis Ltd  2022
    Abstract
    We propose and analyze a circularly polarized slot antenna built on a ferrite substrate which is saturated normal to its plane and metalized on both sides. The antenna is built by etching a circular slot in the top metal layer. The antenna operates in the frequency range where the effective permeability of ferrite is negative. An accurate analytical model is derived for the antenna by solving the integral equation for the electric field on the circular slot. The results obtained are in good agreement with numerical simulations. Using the analytical results, a practical antenna is designed that uses a microstrip feed line. For an antenna with inner and outer radii of 4.9 and 5.9 mm, the... 

    Entropy-minimized optimization of an automotive air conditioning and HVAC system

    , Article SAE 2001 World Congress, Detroit, MI, 5 March 2001 through 8 March 2001 ; 2001 ; 01487191 (ISSN) Heydari, A ; Jani, S ; Sharif University of Technology
    SAE International  2001
    Abstract
    This paper describes an integrated engineering approach for a mathematical modeling of an automotive air-conditioner system and method for performing heating and cooling load calculations of a vehicle shell assembly for designing an HVAC system for a passenger vehicle. In addition, there is presented a physical optimization technique based on minimization of the total entropy generation for the vehicle air-conditioner and HVAC system. Simultaneous solution of the automotive air-conditioning, air handling and the passenger cabin thermal model provide the transient temperature history for consideration of passenger comfort conditions. The validity of the mathematical model was confirmed using... 

    Time Optimal Closed-Loop Attitude Control of Magnetic Actuated Satellites Using Neural Networks

    , M.Sc. Thesis Sharif University of Technology Heydari, Ali (Author) ; Pourtakdoust, Hossein (Supervisor)
    Abstract
    Using magnetic torquers as the sole actuator for attitude control of small satellite despite its benefits has a drawback that is lack of controllability. Mechanical torques can be created only perpendicular to the instantaneous magnetic field vector, thus at each time instant the satellite can be controlled only around two axes out of its three perpendicular axes.
    Fortunately because of the satellite motion, the direction of uncontrollable axis changes by time, therefore the sufficient attitude control can be achieved along time. Almost all of the present magnetic attitude control methods need more than one orbital period to control and cause the attitude to converge to the desired... 

    Heat Transfer Modeling of Ultrasounic Hyperthermia

    , M.Sc. Thesis Sharif University of Technology Heydari, Mohsen (Author) ; Jahed, Mehran (Supervisor)
    Abstract
    Ultrasound hyperthermia is a commonly used noninvasive approach to destroy cancer tumors. High Intensity Focused Ultrasound (HIFU) is a technique based on hyperthermia. It creates short and local elevations of temperature at a focus site within the tissue of interest. The main goal of HIFU is to maintain the temperature between 50 and 100 °C for a few seconds (typically less than 10 s), in order to cause tissue necrosis. In order to predict the effects of hyperthermia, accurate and effective modeling is needed. This study considers a 3D simulation of the hyperthermia based on HIFU method in the liver tissue. Temperature distribution and lesion volume changes, with a temperature of above...