Optimal Monetary Policy with Attention to Housing Price in the Economy of Iran: DSGEApproach

, M.Sc. Thesis Sharif University of Technology Bagherpour, Alireza (Author) ; Dargahi, Hassan (Supervisor) ; Ebrahimi, Illnaz (Supervisor)

Abstract

Purpose of this study is the assignment of the optimal monetary policy rule with attention to housing price with base of setting and to estimating a Dynamic Stochastic General Equilibrium modeling (DSGE). This study has two steps. In the first step we set a model with base of Households, firms, government, and monetary sector behavior and with attention to important variables like outcome, consumption, and investment, the model will be caliber and by simulation it will be evaluated. In the second step we determine optimal monetary rule and the model simulate again with this monetary rule. The comparison between two simulation for verity of shocks shows us that the optimal monetary policy...

Soil Moisture Monitoring in Precision Agriculture Using Estimation Theories

, Ph.D. Dissertation Sharif University of Technology Pourshamsaei Dargahi, Hossein (Author) ; Nobakhti, Amin (Supervisor)

Abstract

Monitoring of soil moisture plays an essential role in correct decision making and implementation of any closed loop control system in precision agriculture. On the one hand, continuous using of a lot of moisture sensors and monitoring of soil moisture via direct measurement is restricted by practical prohibitions. On the grounds that activation of a lot of sensors continuously requires communication of a large amount of information and causes high power consumption for a moisture monitoring system. On the other hand, using remote sensing methods such as satellite methods, for moisture monitoring in arbitrary spatial and time resolution for control purposes, is not practically possible. The...

Performance Improvement of Reinforcement Learning in Non-stationary Environments Using Predictions About Abrupt Environment Changes

, Ph.D. Dissertation Sharif University of Technology Pourshamsaei Dargahi, Hossein (Author) ; Nobakhti, Amin (Supervisor)

Abstract

Reinforcement learning in one of the machine learning paradigms in which the agent is seeking to find the optimal policy by interaction with the environment and achieving rewards according to the selected actions. Reinforcement learning has many different applications, such as robotics, control of dynamic systems, industrial automation and etc. In many of the reinforcement learning problems, it is assumed that the environment model does not change over time, while in some problems, reward and state transition probability functions are not necessarily stationary. These problems are referred to as reinforcement learning problems in non-stationary environments. In some real-life applications,...

Synthesis & Characterization of Nano Zeolite SAPO-34 Membranes on Alumina Supports and Evaluation of Their Performance for Gas and Vapor Separation

, M.Sc. Thesis Sharif University of Technology Dargahi, Mahdi (Author) ; Soltanieh, Mohammad (Supervisor) ; Kazemian, Hossein (Supervisor)

Abstract

A Novel synthesis method to assemble of nano crystalline SAPO-34 molecular sieves crystalline is successfully developed at a supercritical condition. The environmental and operating conditions are investigated through a Taguchi L-9 orthogonal array and optimum synthesis conditions in order to reach highest crystallinity and smallest crystalline. The products were characterized by X-ray diffraction (XRD), scanning electron microscope (SEM), thermal method of analysis (e.g. TG-DTA), and infra red spectroscopy (FT-IR) techniques. In comparison to conventional hydrothermal methods, using a supercritical hydrothermal approach leads to the higher purity, reduced particle size, and change of...

High temperature synthesis of SAPO-34: applying an L9 taguchi orthogonal design to investigate the effects of experimental parameters

, Article Powder Technology ; Volume 217 , February , 2012 , Pages 223-230 ; 00325910 (ISSN) Dargahi, M ; Kazemian, H ; Soltanieh, M ; Hosseinpour, M ; Rohani, S ; Sharif University of Technology

2012

Abstract

SAPO-34 zeolite-like particles were successfully synthesized at high temperature environment. An L9 orthogonal array of the Taguchi method was implemented to investigate the effects of experimental conditions to prepare SAPO-34 with respect to crystallinity of the final product phase. The results showed that the favorable phase crystallinity was improved by increasing the hydrothermal synthesis temperature and organic template content, whereas increasing the water content in synthesis mixture decreased the crystallinity. No significant changes in crystallinity of the final products were observed by increasing the synthesis duration. In addition, zeolite SAPO-5, which was formed as the...

Rapid high-temperature synthesis of SAPO-34 nanoparticles

, Article Particuology ; Volume 9, Issue 5 , October , 2011 , Pages 452-457 ; 16742001 (ISSN) Dargahi, M ; Kazemian, H ; Soltanieh, M ; Rohani, S ; Hosseinpour, M ; Sharif University of Technology

2011

Abstract

Decreasing particle size results in larger increase of external surface area and shorter diffusion path, both reducing mass and heat transfer resistances in catalysis and sorption. A rapid high-temperature hydrothermal synthesis method was developed to synthesize uniform nanoparticles of SAPO-34 zeolite with high crystallinity. To investigate the effects of temperature and synthesis time on purity and crystallinity of the final products, the crystallization temperature was increased from 468 to 673 K while the synthesis time was decreased from 24 h to 45 min. The products were characterized by XRD and SEM techniques. It was found that high temperature and short synthesis time reduce the...

Integration of blockchain with connected and autonomous vehicles: vision and challenge

, Article Journal of Data and Information Quality ; Volume 14, Issue 1 , 2022 ; 19361955 (ISSN) Dargahi, T ; Ahmadvand, H ; Alraja, M. N ; Yu, C. M ; Sharif University of Technology

Association for Computing Machinery 2022

Abstract

Connected and Autonomous Vehicles (CAVs) are introduced to improve individuals' quality of life by offering a wide range of services. They collect a huge amount of data and exchange them with each other and the infrastructure. The collected data usually includes sensitive information about the users and the surrounding environment. Therefore, data security and privacy are among the main challenges in this industry. Blockchain, an emerging distributed ledger, has been considered by the research community as a potential solution for enhancing data security, integrity, and transparency in Intelligent Transportation Systems (ITS). However, despite the emphasis of governments on the transparency...

Designing a dimmable OPPM-based VLC system under channel constraints

, Article 10th International Symposium on Communication Systems, Networks and Digital Signal Processing, CSNDSP 2016, 20 July 2016 through 23 July 2016 ; 2016 ; 9781509025268 (ISBN) Chizari, A ; Jamali, M. V ; Abdollahramezani, S ; Salehi, J. A ; Dargahi, A ; Sharif University of Technology

Institute of Electrical and Electronics Engineers Inc 2016

Abstract

In this paper, we design a dimming compatible visible light communication (VLC) system in a standard office room according to illumination standards under channel constraints. We use overlapping pulse position modulation (OPPM) to support dimming control by changing the code weights. The system parameters such as a valid interval for dimming together with an upper bound for bit rate according to the channel delay spread are investigated. Moreover, considering the dispersive VLC channel and using Monte Carlo (MC) simulations, a method is proposed to determine the minimum code length in different dimming levels in order to achieve a valid bit error rate (BER). Finally, trellis coded modulation...

Visible light for communication, indoor positioning, and dimmable illumination: a system design based on overlapping pulse position modulation

, Article Optik ; Volume 151 , 2017 , Pages 110-122 ; 00304026 (ISSN) Chizari, A ; Jamali, M. V ; Abdollahramezani, S ; Salehi, J. A ; Dargahi, A ; Sharif University of Technology

2017

Abstract

In this paper, we design a dimming compatible visible light communication (VLC) system with asynchronous and optimum indoor positioning method in a standard office room in combination with asynchronous and optimum indoor positioning method according to illumination standards under channel constraints. We use overlapping pulse position modulation (OPPM) to support dimming control by changing the code weights. The system parameters such as a valid interval for dimming together with an upper bound for bit rate according to the channel delay spread are investigated. Moreover, considering the dispersive VLC channel and using Monte Carlo (MC) simulations, a method is proposed to determine the...

Structural Design of a Launch Vehicle with Reusable First Stage

, M.Sc. Thesis Sharif University of Technology Hassan Jamaklu (Author) ; Haddadpour, Hassan (Supervisor)

Abstract

Aerodynamics loads and aeroheating during reentry, are one of the challenging issues in designing One of the main challenges in the design and application of reusable spacecrafts is the aerodynamic and thermal loads acting on their structures during reentry into the atmosphere. For this reason, all the concepts/prototypes presented in the 20th century were either not fully reusable, or were partially canceled, or did not have economic justification. In this report, the aerodynamic loads on the first stage of a launch vehicle during the launch and return phases have been investigated. Due to the fact that the main part of the first stage of the vehicle includes fuel and oxidizer tanks, the...

Optimal Trajectory Correction for Hazardous Near-Earth Asteroids

, M.Sc. Thesis Sharif University of Technology Farsi, Salman (Author) ; Zohoor, Hassan (Supervisor) ; Sayyadi, Hassan (Supervisor)

Abstract

The collision of moderately large asteroids and comets also referred to as Near-Earth Objects (NEO's) with earth would have catastrophic consequences. Such events have occurred in the past and may occur again in the future. However, for the first time in known history, humanity may have the technology required to counter this threat. Methods studied for mitigation of this hazard are based on deflecting asteroid's trajectory and are normally divided into two basic categories: high energy impulsive methods, and long-duration low-thrust methods. Two parts of mission to be optimized are the trajectory of spacecraft to reach the target and the deflection strategy which could be analyzed by the...

A revised version of ACO for cutting stock problem [electronic resource]

, Article International Journal of Industrial Engineering ; Vol 15, No 4 (2008), Pages 341-348 Eshghi, K. (Kourosh) ; Javanshir, Hassan ; Sharif University of Technology

Abstract

The one-dimensional cutting stock problem has many applications in industries and during the past few years has been one of the centers of attention among the researchers in the field of applied operations research. In this paper, a revised version of Ant Colony Optimization (ACO) technique is presented to solve this problem. This paper is a sequel to the previous ACO algorithm presented by the authors. In this algorithm, according to some probabilistic rules, artificial ants will select cutting patterns and generate a feasible solution. Computational results show the high efficiency and accuracy of the proposed algorithm for solving one- dimensional cutting stock problem

Control of Car-Like Multi Robots for Following and Hunting of Moving Target

, M.Sc. Thesis Sharif University of Technology Kouhi Gilvan, Hamed (Author) ; Sayyaadi, Hassan (Supervisor) ; Salarieh, Hassan (Co-Advisor)

Abstract

The main purpose of the present thesis is to establish a decentralized controller for some car–like multi robots to follow and hunt moving targets. Robots are very similar to actual cars considering geometric dimensions, mass and moment of inertia and so on; and outputs of the controller are steering-wheel and driving-wheel torques appropriately. Dynamics of the moving target is so that it escapes from the robots. Robots are equipped with antenna for getting wireless sensory signals, including range and bearing sensors. Kalman filter is used for estimation the target relative position and speed and robots state variables. The controller is designed for doing the above mentioned group...

Stock Price Forecasting Using Neural Networks and Fuzzy Logic

, M.Sc. Thesis Sharif University of Technology Alizadeh, Parisa (Author) ; Shavandi, Hassan (Supervisor)

Abstract

This research proposes a novel hybrid method for stock price index forecasting relying on technical analysis, the fundamental analysis of capital market, neural networks technology, and fuzzy logic. The new method shows a good performance comparing complicated and time-consuming forecasting methods. Several factors influence stock price; for example, an important one is the previous trend of stock price. Fortunately, by developing technical analysis and introducing the various indices of this method the maximum use of historical data is made in order to forecast future prices. Another kind of factors is macro-economic variables that their influence on the long-term trends of the stock...

Control of a Group of Mobile Manipulators for Cooperative object Transportation

, M.Sc. Thesis Sharif University of Technology Babaee, Mohammad (Author) ; Sayyadi, Hassan (Supervisor)

Abstract

In this thesis control of wheeled mobile manipulators for cooperative object transportation is investigated. Full dynamic model of a mobile manipulator with a three wheeled mobile base and a three DOF manipulator is derived using Gibbs-Appell method. Input-output linearization technique is used to control individual robots. Transporting the object is divided into two steps, first robots use a decentralized behavior-based method to approach and surround the object. Then virtual structure method is used to control the robots to transport the object cooperatively. Simulation results with three robots handling an object are presented to show the effectiveness of proposed method

Dynamic and Control of Tethered Satellite Systems

, M.Sc. Thesis Sharif University of Technology Yousefian, Peyman (Author) ; Salarieh, Hassan (Supervisor)

Abstract

In this work dynamic behavior of a two body TSS with main satellite as rigid body is studied and effects of tether elasticity and tension on the satellite dynamic are indicated in station keeping phase and circular orbit. Also a simplified modeling is introduced which could be used in nonlinear controller design. Lagrange and extended Lagrange method is used to derive equations of motion. It is shown that longitudinal vibration of tether has small effect on satellite attitude and angular velocity and because of high frequency it can be decoupled from satellite dynamic. In the simplified model, orbital motion is decoupled from equations of TSS and main satellite dynamic. Effect of decoupling...

Analysis of Control of Nonlinear Switched Systems

, M.Sc. Thesis Sharif University of Technology Toorani, Amin (Author) ; Zohoor, Hassan (Supervisor)

Abstract

Separate analysis of modern systems by continuous or discrete theories is not possible, because they cannot solely express the detailed descriptions of a system. As a result of this, researchers are motivated to study hybrid systems. Specific class of hybrid systems which consists of several continuous subsystems and a rule that specifies how to switch between them, is called a switched system. Recently, many studies have been done on the stability and control of switched systems. In this regard, the goal of present study is presenting applications of switched systems using two control methods. The first application is control of a chemical reactor system with multiple modes. We presented...

Design and Analysis of a Cable Based Robot Similar to a Human Hand

, M.Sc. Thesis Sharif University of Technology Abyaneh, Soroush (Author) ; Zohoor, Hassan (Supervisor)

Abstract

The application of manipulators is becoming more and more popular in objects handling especially when it is desired to have access to remote areas in destructive or hazardous taskspaces. For this purpose, a hand-like mechanism must be designed to be used as an end-effector, which can grasp objects. In this paper a cable driven grasping mechanism has been presented. In the proposed mechanism each finger consists of three phalanxes which are actuated by a single motor. Also, locking and unlocking constraints are used in the mechanism in order to generate an anthropomorphic motion, in which, the order of reaching phalanxes to the object is sequential, in such a way that each phalanx starts...

Data Integration with Multiple Ontologies in Semantic Sensor Web

, M.Sc. Thesis Sharif University of Technology Sadeghi, Shahrouz (Author) ; Abolhassani, Hassan (Supervisor)

Abstract

Sensor Observation Service (SOS) which is defined by Open Geospatial Consortium (OGC) Sensor Web Enablement group is a Web service specification in order to standardize the way sensors and sensor data are discovered and accessed on the Sensor Web. Multiple instances of this service can be implemented around the world, providing huge amount of data every moment. Each of these services operates in specific domain of knowledge (thematic), spatial and temporal dimensions. One way to reveal the underlying data over all of them is to provide an architecture for data integration to allow the user to query sensor data without the knowledge of the infrastructure components. In this research, a novel...

Crack Detection on Rotary Elements Using Vibration Analysis

, M.Sc. Thesis Sharif University of Technology Ari, Mostafa (Author) ; Sayyaddi, Hassan (Supervisor)

Abstract

Rotating machinery are found in most industrial units, that are highly susceptible to transverse cross sectional cracks due to fatigue. The vibration pattern of a rotor system reflects the mechanical parameter changes in the system. These vibrations can be used for identifying the cracks and appropriate actions can be taken to prevent more damage to the system. The dynamic behavior of cracked rotor is a subject of considerable current interest. Several researchers have developed models of cracked rotor systems. Therefore, In this thesis, the influence of the presence of transverse cracks in a simple Jeffcott rotor is analyzed. In first, on the basis of fracture mechanics, the direct and...