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arabzadeh-jamali--hamzeh
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Spontaneous Order of Market and Institutional Challengaes
, M.Sc. Thesis Sharif University of Technology ; Mirjalili, Hossein (Supervisor)
Abstract
Hayek is one of the most impressive figures of Austrian School of Economics established by Carl Menger. The Thinkers of this school of thought believed that governments should not intervene in the market process. They argued that such interventions would spoil the market performance in resource allocation. Hayek believes that the order which emerges from the market is a spontaneous one; it means no one has designed it, but it has evolutionarily evolved by distinctive agents' actions who had no plan to make it. Hayek's arguments for spontaneous order are based on some epistemological presuppositions such as: "methodological individualism", "methodological subjectivism", "tacit knowledge" and...
Construction cost estimation of spherical storage tanks: artificial neural networks and hybrid regression—GA algorithms
, Article Journal of Industrial Engineering International ; 2017 , Pages 1-10 ; 17355702 (ISSN) ; Niaki, S. T. A ; Arabzadeh, V ; Sharif University of Technology
2017
Abstract
One of the most important processes in the early stages of construction projects is to estimate the cost involved. This process involves a wide range of uncertainties, which make it a challenging task. Because of unknown issues, using the experience of the experts or looking for similar cases are the conventional methods to deal with cost estimation. The current study presents data-driven methods for cost estimation based on the application of artificial neural network (ANN) and regression models. The learning algorithms of the ANN are the Levenberg–Marquardt and the Bayesian regulated. Moreover, regression models are hybridized with a genetic algorithm to obtain better estimates of the...
Construction cost estimation of spherical storage tanks: artificial neural networks and hybrid regression—GA algorithms
, Article Journal of Industrial Engineering International ; Volume 14, Issue 4 , 2018 , Pages 747-756 ; 17355702 (ISSN) ; Akhavan Niaki, S. T ; Arabzadeh, V ; Sharif University of Technology
SpringerOpen
2018
Abstract
One of the most important processes in the early stages of construction projects is to estimate the cost involved. This process involves a wide range of uncertainties, which make it a challenging task. Because of unknown issues, using the experience of the experts or looking for similar cases are the conventional methods to deal with cost estimation. The current study presents data-driven methods for cost estimation based on the application of artificial neural network (ANN) and regression models. The learning algorithms of the ANN are the Levenberg–Marquardt and the Bayesian regulated. Moreover, regression models are hybridized with a genetic algorithm to obtain better estimates of the...
Multi-rate and multi-quality of service passive optical network based on hybrid WDM/OCDM system [electronic resource]
, Article IEEE Communications Magazine ; February 2011, Volume 49, Issue 2, PP. S39-S44 ; Salehi, J. A ; Sharif University of Technology
Abstract
In this article we present a new scheme to support multirate and multi-quality-of-service transmission in passive optical networks based on a hybrid wavelength-division multiplexing/optical code-division multiplexing scheme. The idea is to use multilength variable-weight optical orthogonal codes as signature sequences of a hybrid WDM/OCDM system. To provide the requested classes of service, the code weight and code length of MLVW-OOCs are designed based on the characteristics of the requested classes of service. In order to mitigate multiple access interference, we propose to utilize a multilevel signaling technique and interference remover structure based on advanced optical logic gate...
Investigating Performance Bottlenecks for Efficient Implementation of MapReduce in Hadoop
, M.Sc. Thesis Sharif University of Technology ; Goudarzi, Maziar (Supervisor)
Abstract
Ever-increasing development and growth of information volume is an unprecedented phenomenon. Analyzing and saving such enormous volume of information calls for innovative ideas capable of processing and managing this information. One of the successful projects in this regard done by Apache is known as Hadoop.Hadoop is a popular open-source implementationof MapReduce processing schemefor analysis of large datasets. The heart of Hadoop is MapReduce that is a parallel programming model for data processing on clusters. To handle storage resources across the cluster, Hadoop employs a distributeduser-level filesystem. The Hadoop Distributed File System (HDFS) is written in Java and is designed for...
Design and Fabrication of an Ejector Refrigeration Cycle
, M.Sc. Thesis Sharif University of Technology ; Hakkakifard, Ali (Supervisor)
Abstract
Due to 18000 MW power consumption of cooling systems from the total Iranian electricity consumption in 2016 and hitting a new peak in 2017, the need for finding other alternatives that consume less electrical energy is inevitable. Hence, instead of buildings new power plants, only to meet the demand at the peak of power consumption, using new solutions to reduce consumption seems more beneficial. One way to reduce consumption is to switch to ejector refrigeration systems. One of the main advantages of these systems is their ability to cooling using low-grade waste energies or solar energy (as a heat source below 80℃). However, in absorption systems, the minimum temperature of the heat source...
Power quality comparison of active islanding detection methods in a single phase PV grid connected inverter
, Article IEEE International Symposium on Industrial Electronics, 5 July 2009 through 8 July 2009 ; 2009 , Pages 1852-1857 ; 9781424443499 (ISBN) ; Mokhtari, H ; Sharif University of Technology
2009
Abstract
In this paper, the power quality of a single-phase photovoltaic grid connected inverter when uses active islanding detection methods is investigated. Two main groups of these methods are analyzed in this paper. The main focus is on the output power quality of PV sources for these methods. Also the variation of output current THD, while the output power changes, is explored. The variation of output current THD is measured when the parameters of active islanding detection method are changed, and the limitation of these parameters for complying power quality standards in the nominal output power is detected. ©2009 IEEE
A proposed mechanism for mind-brain interaction using extended Bohmian quantum mechanics in Avicenna's monotheistic perspective
, Article Heliyon ; Volume 5, Issue 7 , July , 2019 ; 24058440(ISSN) ; Golshani, M ; Jamali, Y ; Sharif University of Technology
Elsevier Ltd
2019
Abstract
In quantum approaches to consciousness, the authors try to propose a model and mechanism for the mind-brain interaction using modern physics and some quantum concepts which do not exist in the classical physics. The independent effect of mind on the brain has been one of the challenging issues in the history of science and philosophy. In some recent mind-brain interaction models, the direct influence of mind on matter is either not accepted (as in Stapp's model) or not clear, and there have not been any clear mechanism for it (as in Penrose-Hameroff's model or in Eccles's model). In this manuscript we propose a model and mechanism for mind's effect on the matter using an extended Bohmian...
A proposed mechanism for mind-brain interaction using extended Bohmian quantum mechanics in Avicenna's monotheistic perspective
, Article Heliyon ; Volume 5, Issue 7 , 2019 ; 24058440 (ISSN) ; Golshani, M ; Jamali, Y ; Sharif University of Technology
Elsevier Ltd
2019
Abstract
In quantum approaches to consciousness, the authors try to propose a model and mechanism for the mind-brain interaction using modern physics and some quantum concepts which do not exist in the classical physics. The independent effect of mind on the brain has been one of the challenging issues in the history of science and philosophy. In some recent mind-brain interaction models, the direct influence of mind on matter is either not accepted (as in Stapp's model) or not clear, and there have not been any clear mechanism for it (as in Penrose-Hameroff's model or in Eccles's model). In this manuscript we propose a model and mechanism for mind's effect on the matter using an extended Bohmian...
Optimization of Endurance Time Acceleration Function using Fourier and Wavelet Transform and Optimization Algorithms
, M.Sc. Thesis Sharif University of Technology ; Esmaeil Purestekanchi, Homayoon (Supervisor)
Abstract
So far, several studies have been conducted on the endurance time method. In general, these studies can be categorized into two categories. The first group of studies are based on the theoretical foundations of this methodology and the second group of researches that use the method of endurance time in different engineering issues of earthquake and engineering, and also compare the results of this method with other conventional methods of seismic analysis.The purpose of this study, which is more in the first category of research, is to optimize the acceleration functions using various Transform, such as Fourier and Wavelet, as well as the use of various optimization algorithms. In optimizing...
Domain Dependent Regularization in Online Optimization
, M.Sc. Thesis Sharif University of Technology ; Jafari Siavoshani, Mahdi (Supervisor)
Abstract
As application demands for online convex optimization accelerate, the need for design-ing new methods that simultaneously cover a large class of convex functions and im-pose the lowest possible regret is highly rising. Known online optimization methods usually perform well only in specific settings, e.g., specific parameters such as the diam-eter of decision space, Lipschitz constant, and strong convexity coefficient, where their performance depends highly on the geometry of the decision space and cost functions. However, in practice, the lack of such geometric information leads to confusion in using the appropriate algorithm. To address these issues, some adaptive methods have been proposed...
Analysis and Countermeasure of Android Malware Generation Using Adversarial Example Generation Methods
, M.Sc. Thesis Sharif University of Technology ; Amini, Morteza (Supervisor)
Abstract
The widespread use of the Android operating system has made it an attractive target for attackers. In the field of malware identification and mitigation, the use of machine learning methods has seen significant advancements due to their ability to identify unknown malware. One of these methods is graph-based techniques in constructing malware detection systems, which have achieved high success rates in identifying malware. However, machine learning methods suffer from the vulnerability of being misled by adversarial examples. One important aspect in both malware detection systems and adversarial attacks is the limitations imposed on software modification. Any changes made to the application...
A decentralized self-adjusting control strategy for reactive power management in an islanded multi-bus MV microgrid
, Article Canadian Journal of Electrical and Computer Engineering ; Volume 36, Issue 1 , 2013 , Pages 18-25 ; 08408688 (ISSN) ; Mokhtari, H ; Karimi, H ; Sharif University of Technology
2013
Abstract
This paper presents a decentralized self-adjusting reactive power controller for the autonomous operation of a multi-bus medium voltage (MV) microgrid. The main objective of the proposed control strategy of each distributed generation (DG) unit is to compensate the reactive power of its local loads and to share the reactive power of the nonlocal loads among itself and other DG units. The proposed control strategy includes an improved droop controller whose parameters are adjusted according to the reactive power of the local loads. A virtual inductive impedance loop is augmented to the voltage controller to enhance the steady state and transient responses of the proposed reactive power...
A new control strategy for a multi-bus MV microgrid under unbalanced conditions
, Article IEEE Transactions on Power Systems ; Volume 27, Issue 4 , 2012 , Pages 2225-2232 ; 08858950 (ISSN) ; Karimi, H ; Mokhtari, H ; Sharif University of Technology
2012
Abstract
This paper proposes a new control strategy for the islanded operation of a multi-bus medium voltage (MV) microgrid. The microgrid consists of several dispatchable electronically-coupled distributed generation (DG) units. Each DG unit supplies a local load which can be unbalanced due to the inclusion of single-phase loads. The proposed control strategy of each DG comprises a proportional resonance (PR) controller with an adjustable resonance frequency, a droop control strategy, and a negative-sequence impedance controller (NSIC). The PR and droop controllers are, respectively, used to regulate the load voltage and share the average power components among the DG units. The NSIC is used to...
Robust backstepping control of an interlink converter in a hybrid AC/DC microgrid based on feedback linearisation method
, Article International Journal of Control ; Volume 90, Issue 9 , 2017 , Pages 1990-2004 ; 00207179 (ISSN) ; Sadati, N ; Hamzeh, M ; Sharif University of Technology
2017
Abstract
This paper presents a robust dc-link voltage as well as a current control strategy for a bidirectional interlink converter (BIC) in a hybrid ac/dc microgrid. To enhance the dc-bus voltage control, conventional methods strive to measure and feedforward the load or source power in the dc-bus control scheme. However, the conventional feedforward-based approaches require remote measurement with communications. Moreover, conventional methods suffer from stability and performance issues, mainly due to the use of the small-signal-based control design method. To overcome these issues, in this paper, the power from DG units of the dc subgrid imposed on the BIC is considered an unmeasurable...
Primary and secondary frequency control in an autonomous microgrid supported by a load-shedding strategy
, Article PEDSTC 2013 - 4th Annual International Power Electronics, Drive Systems and Technologies Conference ; 2013 , Pages 282-287 ; 9781467344845 (ISBN) ; Ameli, M. T ; Hamzeh, M ; Sharif University of Technology
2013
Abstract
This paper proposes a frequency control strategy for an islanded inverter-based microgrid which based on the priority of supply, has got two distinct types of loads, namely sensitive and deferrable. The proposed strategy consists of primary and secondary levels of generation control supported by a loadshedding scheme. The primary control regulates the output power of the distributed generator (DG) units to be proportional to their ratings while secondary control has got the duty of frequency restoration after each load change. Functionality of these two levels is demonstrated to be independent of each other. Both controls are in distributed forms which have no need of communication...
Robust backstepping control of an interlink converter in a hybrid AC/DC microgrid based on feedback linearisation method
, Article International Journal of Control ; 2016 , Pages 1-15 ; 00207179 (ISSN) ; Sadati, N ; Hamzeh, M ; Sharif University of Technology
Taylor and Francis Ltd
2016
Abstract
This paper presents a robust dc-link voltage as well as a current control strategy for a bidirectional interlink converter (BIC) in a hybrid ac/dc microgrid. To enhance the dc-bus voltage control, conventional methods strive to measure and feedforward the load or source power in the dc-bus control scheme. However, the conventional feedforward-based approaches require remote measurement with communications. Moreover, conventional methods suffer from stability and performance issues, mainly due to the use of the small-signal-based control design method. To overcome these issues, in this paper, the power from DG units of the dc subgrid imposed on the BIC is considered an unmeasurable...
A backstepping high-order sliding mode voltage control strategy for an islanded microgrid with harmonic/interharmonic loads
, Article Control Engineering Practice ; Volume 58 , 2017 , Pages 150-160 ; 09670661 (ISSN) ; Sadati, N ; Hamzeh, M ; Sharif University of Technology
Elsevier Ltd
2017
Abstract
This paper presents a new nonlinear voltage control strategy based on backstepping control and a high-order sliding mode differentiator for an islanded microgrid. The microgrid consists of multiple distributed generation (DG) units with an arbitrary configuration that can be parametrically uncertain or topologically unknown. The proposed controller robustly regulates the microgrid voltages in the presence of parametric uncertainties, unmodeled dynamics, load imbalances, and nonlinear loads with harmonic/interharmonic currents. In contrast to existing methods, the controller does not need to know the frequency of harmonic and interharmonic current of microgrid loads that lead to the reduction...
Distributed robust finite-time secondary voltage and frequency control of islanded microgrids
, Article IEEE Transactions on Power Systems ; Volume 32, Issue 5 , 2017 , Pages 3648-3659 ; 08858950 (ISSN) ; Sadati, N ; Hamzeh, M ; Sharif University of Technology
2017
Abstract
This paper presents a distributed, robust, finite-time secondary control for both voltage and frequency restoration of an islanded microgrid with droop-controlled inverter-based distributed generators (DGs). The distributed cooperative secondary control is fully distributed (i.e., uses only the information of neighboring DGs that can communicate with one another through a sparse communication network). In contrast to existing distributed methods that require a detailed model of the system (such as line impedances, loads, other DG units parameters, and even the microgrid configuration, which are practically unknown), the proposed protocols are synthesized by considering the unmodeled...
A robust backstepping high-order sliding mode control strategy for grid-connected DG units with harmonic/interharmonic current compensation capability
, Article IEEE Transactions on Sustainable Energy ; Volume 8, Issue 2 , 2017 , Pages 561-572 ; 19493029 (ISSN) ; Sadati, N ; Hamzeh, M ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2017
Abstract
This paper presents a new nonlinear current control strategy based on backstepping control and high-order sliding mode differentiator in order to employ distributed generation (DG) unit interfacing converters to actively compensate harmonics/interharmonics of local loads. The converter-based DG unit is connected to a weak grid (with uncertain impedance) and local load (that can be parametrically uncertain and topologically unknown) through an LCL filter. The proposed strategy robustly regulates the inverter output currents and delivers pure sinusoidal, three-phase balanced currents to the grid. The new controller demonstrates the robust performance and robust stability of the DG unit system...