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,...

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...

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...

MBBR and MBR Reactor Configuration for Better Performance

, M.Sc. Thesis Sharif University of Technology (Author) ; Borgheei, Mahdi (Supervisor)

Abstract

Membrane bioreactors (MBRs) which are commonly understood as the combination of membrane filtration and biological treatment using activated sludge have several advantages, but membrane fouling reduces the membrane efficiency, permeability and lifetime. An alternative is replacing a moving bed biofilm reactor (MBBR) with the activated sludge system which may reduce the effect of membrane fouling. The sludge produced in MBBRs has poor settling characteristics, therefore, their efficiency is limited by the sedimentation tank performance and they require a larger settling surface. The combination of moving bed biofilm reactors and membrane bioreactors can compensate for the drawbacks of both of...

Forecasting the effects of a Canada-US currency union on output and prices: A counterfactual analysis

, Article Journal of Forecasting ; Volume 32, Issue 7 , 2013 , Pages 639-653 ; 02776693 (ISSN) Mahdi Barakchian, S ; Sharif University of Technology

2013

Abstract

This paper is a counterfactual analysis investigating the consequences of the formation of a currency union for Canada and the USA: whether outputs increase and prices decrease if these countries form a currency union. We use a two-country cointegrated model to conduct the counterfactual analysis, where the conditional forecasts are generated based on the Gaussian assumption. To deal with structural breaks and model uncertainty, conditional forecasts are generated from different models/estimation windows and the model-averaging technique is used to combine the forecasts. We also examine the robustness of our results to parameter uncertainty using the wild bootstrap method. The results show...

Evaluation of Non-linear Combination Method (Neural Network) For Value-at-Risk Forecasting in Market

, M.Sc. Thesis Sharif University of Technology Rashnavadi, Leila (Author) ; Barakchian, Mahdi (Supervisor)

Abstract

Value at risk of an asset, is the asset’s expected maximum loss for a certain period of time and at a specified confidence level. Value-at-Risk can be calculated in the bank with its inter-nal method or standardized method. when a method have more violation number then bank need to keep more daily capital requirements. under the Basel 2 agreement if the violation of method more than 10 times in year, the Bank uses the standardized method.
There are trade off Between daily capital charge and violations. Therefore, existing methods for calculating the value at risk, usually lead to much daily capital charge or many violations. Studies show with combination of different methods to calculate...

Using Complex Network Metrics for Evaluating the Influence of Conference and Journal Papers in Computer Science

, M.Sc. Thesis Sharif University of Technology Habibi, Fatemeh (Author) ; Jalili, Mahdi (Supervisor)

Abstract

Journals and conferences in computer science are the major venue for publishing new achievement in the field. It is an expert opinion that a number of top conferences in computer science are even more important than journals. In this work we aim at studying this in terms of citation analysis. To this end, we took 100 top journals and 63 top conferences and extracted their citation graph through Scopus dataset. We then constructed the citation graph in which the nodes were the journals and conferences and the links corresponded to the citations of the papers. We used various measures to rank the nodes in the graph. The ranking methods included Prestige, PageRank, Eigenfactor, HITS and SALSA....

Design and Implementation of a VLSI Architecture for Time and Frequency Synchronization in the LTE

, M.Sc. Thesis Sharif University of Technology Golnari, Amene (Author) ; Shabany, Mahdi (Supervisor)

Abstract

The long term evolution (LTE) standard is introduced and developed by the 3rd generation partnership project (3GPP) based on orthogonal frequency division multiplexing (OFDM). OFDM systems, in spite of having many advantages such high performance in bandwidth usage, are very sensitive to inter carrier interference (ICI) as a drawback. In order to prevent ICI, the frequency offset, mainly caused by the miss-match between oscillators' frequency and also between the sampling frequency of the transmitter and the receiver, should be estimated and compensated. Frequency synchronization is a part of the tasks of a synchronizer. In this thesis, main tasks of a synchronizer are illustrated and...

A New Approach in Value-at-Risk (VaR) Estimation by Forecast Combination Methods

, M.Sc. Thesis Sharif University of Technology Seraj, Mostafa (Author) ; Barakchian, Mahdi (Supervisor)

Abstract

Value-at-Risk (VaR) is the most commontool for risk management. This tool is used to measure market risk and also used as a basis in determining financial standards for international financial institutions. VaR is the maximum loss of the asset portfolio at the specified confidence level and certain time horizon. Many parametric, nonparametric and semi parametric methods have been invented for VaR estimation. Each one of these methods has its advantages and disadvantages and different methods may perform better in differnet situations.When estimating VaR, we can choose one of these methods or we can combine the VaRs estimated by different methods. There are few researches conducted on VaR...

EEG Brain Functional Network Analysis in Cortex Level

, M.Sc. Thesis Sharif University of Technology Pedrood, Bahman (Author) ; Jalili, Mahdi (Supervisor)

Abstract

Complex networks science have received tremendous attention in recent years and the brain is one of the systems to which graph theoretical tools have been applied. Alzheimer’s disease (AD) is a neurodegenerative disease affecting many of elderly population. AD changes the anatomy of the brain, which subsequently results in changes in its functions. These changes have been frequently reported in signals recorded from the brain (such as MEG, fMRI and EEG). Among these neuroimaging techniques EEG is one of the most aproprate methods for extracting functional connectivites according to high temporal resolution. In this thesis, we aimed at analyzing the properties of EEG-based functional networks...

Learning Improvement in Phase Oscillator Models

, M.Sc. Thesis Sharif University of Technology Aghighi, Meysam (Author) ; Jalili, Mahdi (Supervisor)

Abstract

In the recent years, the problem of modeling a cognitive task using phase oscillators has been receiving a significant attention. In this view, single neurons are no longer elementary computational units. Rather, coherent oscillating groups of neurons are seen as nodes of networks performing cognitive tasks. From this assumption, we develop a model of stimulus-response learning and recognition. The most significant part of our work is defining learning methods for natural frequencies and coupling weights in a coupled phase oscillator network under Kuramoto conditions. In this thesis, we improved the previous models by not only emphasizing on the frequency of the oscillators but also taking...

Evaluation of Caviar Models Incorporated with Intraday Information ,the Case Study:Estimation Value at Risk of Gold

, M.Sc. Thesis Sharif University of Technology Karimi, Parvane (Author) ; Barakchian, Mahdi (Supervisor)

Abstract

Value at risk (VaR) is the maximum loss of the asset portfolio at the specified confidence level and certain time horizon. This tool is used to measure market risk and also used as a basis in determining financial standards for international financial instituation. Conditional Autoregressive Value at Risk models or CAViaR models introduced by Engle and Manganelli (2004). This models calculate VaR base on quantile regession approach and show some promising performance properties.
In order to propose a more accurate model for calcutating VaR , we develop CAViaR models by incorporating them with intraday information then we calculate VaR with this kind of models and CAViaR...

Design and Implementation of a Spectrum Sensor for Cognitive Radio

, M.Sc. Thesis Sharif University of Technology Safavi, Mahya (Author) ; Shabani, Mahdi (Supervisor)

Abstract

Frequency scarcity has emerged the necessity of opportunistic utilization of frequency bands, which can be realized through a cognitive radio system. During an agile communication between unlicensed users, a cognitive radio system must avoid collision with licensed users. Hence it should continuously observe the band of interest and report the presence of licensed user signals. This task is fulfilled by a vital part of a cognitive radio system, called the spectrum sensing core. Recently several techniques have been proposed for the spectrum sensing in literature. Some of them like matched filtering, cyclostationarity based detection are based on primary user signal features. However energy...

VLSI Architecture of Turbo Decoder for LTE

, M.Sc. Thesis Sharif University of Technology Ardakani, Arash (Author) ; Shabany, Mahdi (Supervisor)

Abstract

Long Term Evolution (LTE) aims the peak data rates in excess of 300 Mb/s, which may appear to be challenging to achieve due to the existence of some blocks such as the turbo decoder. One efficient approach to achieve this throughput is by parallelizing the Log Maximum a Posteriori (MAP) algorithm in the turbo decoder. In fact, the interleaver is known to be a major challenging part of the turbo decoder due to its need to the parallel interleaved memory access. LTE uses Quadratic Permutation Polynomial (QPP) interleaver, which makes it suitable for the parallel decoding. In this thesis, first, we propose an efficient architecture for the QPP interleaver, called the Add-Compare-Select (ACS)...