Sharif Digital Repository

High voltage power supplies (HVPS) are widely used to supply the vacuum tubes. The function of this power supply is disturbed by some internal and external faults. One of the external faults is the arc fault in the tube. The amount of delivered energy from the HVPS to the tube is an important issue during the arc fault in the tube. The conventional protection mechanism consists of a shunt crowbar device which divert the fault current from the tube arc. The crowbar circuit is usually built with thyristor in most cases. This type of crowbar cannot be turned off simply by protection command. It is a drawback since if the fault is transient such as arc in the load or false fault detection is... 

In this thesis, we study the resilience of complex systems under structural perturbations. After a brief review of the resilience and its importance, we show that how one can map a system of N-coupled dynamical equations onto an effective one-dimensional dynamics. This procedure is based on a nearest neighbor averaging. The obtained map, helps us study the response of the system to the effective one-dimensional control parameter, instead of all parameters that are affecting the structure of the network. Next, we use this procedure and unveil the resilience pattern of second-order Kuramoto oscillators on complex networks. Moreover, we propose a control strategy for complex systems which is... 

globalization has altered the structure of supply chains and the way they operate. These changes have mainly intensified by novel manufacturing models, especially cloud manufacturing, a service-oriented model in which manufacture’s capabilities and distributed resources are shared through a centralized management and control of CMfg platforms. Thus, cloud manufacturing has enabled service providers to reduce their costs and enhance production speed by creating virtual production lines. However; while being beneficial, cloud manufacturing models can introduce new challenges. One of the goals of cloud manufacturing models is to provide the access to value added services so that available... 

Predicting the trend of stock prices is always one of the concerns that stock market analysts and investors face with, which plays a critical role in maximizing the profit from investing in stocks. Past stock price charts, raw material prices, the value of the company's assets, the impact of global markets, the company's products, the organization's development plans, and the same other factors influencing the stock price. News reports are an important source of information for people. Recently, a lot of research has been done to examine the impact of news on stock price trends. This research has two research phases. In the first phase, a text mining method is presented which is using... 

This research proposes a Bayesian model selection framework using the stochastic filtering for rapid Bayesian identification of structures under seismic excitations. Structural identification after an earthquake at a regional scale entails a high computational effort. For rapid damage detection on a regional scale, using simplified and low-cost structural models is preferred over complex finite element models, due to the large amount of information needed for finite element modeling of numerous structures within a region as well as the high computational cost of such models. Timoshenko beams, shear beams, and shear buildings are examples of simplified structural models used in this study to... 

The growing number of disasters in recent years has become a significant threat to hospital buildings' resilience and preparedness. Besides, the stochastic nature of these disasters and the complexity of the hospital building systems exacerbate the difficulty of making appropriate decisions during and after disasters. To address the issue, this research proposes a novel model that utilizes the capabilities of Bayesian Networks (BNs) and Building Information Modeling (BIM). This model helps decision-makers in hospitals and medical centers measure various effects of disasters on utility systems and analyze the consequences of their decisions. The capabilities of the proposed model are tested... 

Highway bridges are one of the key components of transportation network and play a significciant role in the recovery of societies after extreme events such as flood and earthquake. The dysfunction or failure of bridges significantly impacts commerce and services and cause direct and indirect costs. Thus, the recovery of theses components immediately after extreme events is vital issue. In this study, a framework developed to evaluate the life-cycle resilience of bridges using the Endurance Time method. At the first part, the effect of deterioration due to corrosion on the seimic vulnerability and resilience of RC bridge investigated by ET method. To this aim, a procedure described to... 

The high reliability of energy supply and the compatibility of the energy sector with the environment are essential factors in the process of the economic reconstruction and the sustainable development of countries. Thus, most of our activities, well-functioning of modern societies, and the growth of economies (such as the gross domestic product (GDP) of countries) depend on a reliable and efficient supply of energy. In today’s global and increasingly dynamic and turbulent environments, energy systems and supply energy are challenged with numerous disruptive events which threaten to disrupt the activities and performance of energy systems. There is a bilateral relation between energy sector... 

The number and severity of natural disasters have significantly increased in the recent years. Extreme weather-driven events cause catastrophic damages to power grid components. As a consequence, severe power outages occur in the affected grids. According to the published reports on natural disasters, 90 percent of such outages originate from distribution systems. In addition, the repair process of the damaged elements takes a long duration. Thus, it is necessary to improve the distribution system (DS) resilience against natural disasters. The strategies for resilience enhancement can be classified into two main groups: hardening and operation-oriented measures.Formation of microgrids has... 

Estimation of indirect economic losses due to natural disasters, especially earthquakes, is one of the essential issues in disaster management. This study presents a framework that uses an economic model of the community under study and calculates the indirect economic losses caused by an earthquake. To this end, first, the earthquake-induced direct economic losses are quantified using appropriate risk analysis models. The direct losses are used to characterize the consequent shock to labor and capital. These shocks are then used as inputs to the regional economic model. In the proposed framework, a Computable General Equilibrium (CGE) model uses various data about the state of the community... 

Green project management involves a set of management actions to identify and evaluate the effect of activities on the environment along with controlling and improving performance.Accordingly, the concepts of lean, agility, and resilience have a special place as driving forces since they can play an important role in improving the environment. Thus, this study aimed to identify and prioritize the activities related to green project management considering the concepts of lean, agility, and resilience. The present study identified the dimensions of lean, agility, and resilience for the first time in green project management.Then, this study evaluated the prioritization of activities in terms... 

The severe wildfires in California, Australia, Canada, and Iran have interrupted the power system operation, caused multiple blackouts, took many lives, and caused damages to power grid infrastructure to the extent of millions and billions of dollars. Most of the recent wildfires occur in the distribution system. Therefore, enhancing power system distribution resilience against wildfire is crucial.To this end, two groups of measures are proposed: the hardening of the power network and the operational measures. The past published papers mainly studied the resilience enhancement strategies against wildfire from an operational perspective. There is a considerable gap between the past works... 

The purpose of this study is to present a suitable model for calculating the costs imposed on society due to deaths and injuries due to infrastructure failure due to earthquakes, which is used in the analysis of community resilience. Much research has been done to date to calculate the economic costs of infrastructure failure. However, no suitable analytical framework has been provided to quantify the costs of deaths and injuries to people due to earthquake failure. Previous research has provided methods such as the value of statistical life to quantify the social costs caused by accidents and environmental pollution. However, the literature review results in the field of seismic resilience... 

This thesis extends a probabilistic framework for evaluating the seismic resilience of communities by probabilistic modeling of the telecommunication infrastructure failure and recovery along with its interdependencies with other infrastructures. This framework, Rtx, that is being extended under continuous development at Sharif University of Technology, is based on modeling the community state from hazard incident until complete recovery by a combination of risk and agent-based simulation models. In this thesis the framework is extended with telecommunication infrastructure models. This infrastructure is modeled by developing a library of probabilistic models to predict damage to network... 

The increasing dependence of urban communities on infrastructure highlights the importance of resilience in the event of natural disasters, including earthquakes. Every society is made up of various infrastructures such as water supply, electricity, transportation, hospitals and so on.Every infrastructure to serve the community depends directly or indirectly on the electricity infrastructure.The power supply infrastructure consists of three main systems of electricity generation, transmission and distribution. Power substations, as nodes of the transmission and distribution network, are considered to be very vital nodes that it is important to maintain their serviceability after severe... 

In this thesis, the resilience of energy supply networks and the application of Agent Based Modeling in the resilience analysis of power microgrids are studied. The main idea is to use microgrids as a solution to make power systems resilient. A microgrid with autonomous agents consisting of renewable resources, non-dispatchable generators, dispatchable generators, residential loads, critical loads, battery storages, and microgrid controller is investigated. Each agent is autonomous and has independent behavior such that the interaction between these agents produces emergent phenomena at the system level in the microgrid. In the developed model, residential consumers try to optimize their... 

large-scale data collection from multiple sources to a single entity, such as a cloud provider, poses a challenging problem for implementing centralized machine learning algorithms. Constraints such as privacy protection and restrictive access policies that prevent accessing personally identifiable information hinder the development of centralized machine learning algorithms in important and sensitive domains like healthcare. However, from early disease detection to discovering new drugs, leveraging artificial intelligence in this domain is a fun-damental necessity. As a potential solution, federated learning has been proposed, allowing data owners (users) to jointly train a shared machine... 

Nowadays a lot of people from all around the world travel by inter-city trains and this phenomenon is the direct result of the fact that this travel mode is more affordable and relatively comfortable in comparison to other modes. Furthermore, recent developments such as the emergence of high-speed rail lines have made rail transportation able to compete with other means of transportation such as airplanes. Therefore, the practice of maximizing train networks’ resilience against probable disruptions has drawn significant attention to itself. This study introduces a novel methodology in which train network resilience can be maximized through three stages. In the first stage, the critical nodes...