Sharif Digital Repository

Nowadays, variable generation and renewable energy resources are increasingly penetrating the energy systems to supply the users' demand at the distribution grid. Variable Energy Resources (VER) can provide energy at a lower cost, and they also guarantee cleaner energy. Still, the uncertainty and variability from these resources' output can affect the net-load of the system at each hour. Besides, the issue of energy balance has always been a challenge for the energy distribution networks. A comprehensive way to unravel this problem is to use flexible resources. One of the crucial issues in the flexibility debate is meeting this need by different energy resources. It is always an issue for... 

Nowadays, cancer, which has been mentioned as the disease of the century, is the second leading cause of death throughout the world, and its incidence is constantly increasing. Isolation of circulating tumor cells is one of the most critical steps in diagnosing and controlling cancer progression. Due to the rarity of cancer cells compared to other cells in the blood sample, the isolation process requires optimal and high-precision devices. With the advent of inertial microfluidics, the ability to control the particles movement, the processing of blood samples as quickly and accurately as possible, and the viability of cells with a high percentage, introduced microfluidic systems as a... 

In recent years, electric vehicles (EVs) have emerged as an effective solution to reduce pollution caused by the use of fossil fuels in the transportation sector. While EVs contribute to improved air quality, managing their charging and discharging processes is crucial. To address this, EV aggregators act as intermediaries between EVs and the power grid, primarily responsible for controlling the charging and discharging of a fleet of EVs with the objective of maximizing their profits. On the other hand, to reduce fossil fuel consumption in electricity generation, efforts are underway to transition consumers into prosumers and equip residential complexes with distributed energy resources... 

The study of visibility is at least 100 years old, when in 1913 Brunn proved a theorem about the kernel of a set. By now, visibility has become one of the most studied notions in computational geometry. The reasons are two-fold: 1) such problems arise naturally in areas where computational geometry tools and algorithms _nd applications including: computer graphics, robotics, motion planning, geographic information systems, computer games, computer-aided architecture, and pattern recognition; and where 2) their solutions are required, or serve as building blocks in the development of solutions to other problems, such as shortest paths or motion planning problems. Many natural problem... 

Visibility is an important topic in computational geometry, computer graphics, and motion planning. Two points inside a polygon are visible to each other if their connecting segment remains completely inside the polygon. Visibility polygon of a point in a simple polygon P is the set of points inside P that are visible from the point. The visibility problem has also been considered for line segments. A point v is said to be weakly visible to a line segment pq if there exists a point w 2 pq, such that w and v are visible to each other. The problem of computing the weak visibility polygon (or WVP) of pq inside a polygon P is to compute all points of P that are weakly visible from pq. In this... 

Cryogenics is the study of materials and their behavior at temperatures below -150 degrees Celsius, where gases can liquefy or even solidify. Cryogenics investigates the properties of matter at these cold temperatures, revealing unique physical properties and behaviors that cannot be observed under normal conditions. It is not easy to reach this temperature range and special methods are used to achieve it. The Gifford-McMahon (GM) cycle is one of the most famous thermodynamic cycles for achieving ultra-cold temperatures. When there are limitations for supercooling in terms of space and dimensions, the use of this cycle is more considered. One of the most important parts of this cycle is the... 

People’s interaction and their impressions on each other has been one of the specifications of the societies; which has been studied and are used in various ways for widening the circle of thoughts and introducing the concepts. Low cost of the use of this method and feasibility of controlling the sensitivity about the considered issue (and some times the source of the issue), are the advantages of this advancement. This issue has also had numerous usages in the marketing and business. In this thesis an approximate algorithm has been designed for extracting the structure of the network, diffusion rate and the effective nodes in the network. This algorithm is... 

Two-phase flows are widely used in petrochemical industry, chemical processes, boilers, nuclear reactors, cooling systems and air conditioning equipment. Since the problem of earth’s ozone layer and global warming, the analysis of flow characteristics in evaporators are necessary to improve performance of refrigerating systems and saving the environment. Most of the researchers have been studied the evaporation of two phase flow refrigerant through experimental studies and numerical analysis has less attention in the literature. In this Thesis, a mathematical model based on the two-phase separated flow model is developed to simulate the evaporation of pure refrigerant under constant heat... 

Two phase cross flows around a body have seldom been studied until now and considering these flows can play a significant role in long-term reliability and safety of industrial systems. In this paper flow regimes, drag coefficient and void fraction around different cross-section prisms were considered. To achieve this aim, main equations of flow have been developed for investigation of drag coefficient in air-water two phase. Our numerical analyses were performed by a designed and written CFD package which is based on Eulerian-Eulerian approach. Geometries, which have been studied in this article, are: circle, rectangle and triangle, for different aspect ratio and leading edge angle,... 

In the present study, TiO2-reduced graphene oxide (T-RGO) nanocomposites were synthesized via various in-situ and ex-situ methods, then their photovoltaic performance was examined as photoanode and mesoporous layers in dye-sensitized Solar Cells (DSSCs) and perovskite Solar Cells (PSCs), respectively. Graphene oxide (GO) was prepared using Hummer’s method with some modifications. Both thermal and hydrothermal processes were used to reduce GO. Structural and optical characterization was analytically demonstrated by subjecting of the obtained materials by several techniques, including X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), Raman, thermogravimetric analysis (TGA),... 

The present work has proposed an integrated methodology for combined gas & electricity distribution network expansion planning, which considers network expansion constraints (substation installation, feeder/pipeline installation, etc), load growth, and conversion technologies. The planning aims to determine the optimal reinforcement of existing energy network to meet the load growth in the planning horizon. To take the advantages of new technologies, CHP, fuel cell, & microturbine have been included in the problem.This paper employs gravitational search algorithm (GSA) to solve multi-objective problem, including minimization of cost, voltage drop, & pressure drop. GSA that introduced in... 

Optimizing and reducing energy consumption will be a feature of smart cities in the future. In addition to the technical aspects of a technology, one of the most important obstacles to its lack of development is not considering economic factors. Investigating the economics and calculating the cost of using IoT systems in the energy sectors of a smart city is one of the most important issues. Using existing systems in buildings or adding limited and inexpensive hardware to make a building smart can make smartening a cost-effective operation and more widespread. In this research, a proposed architecture based on edge processing is described. In addition to receiving and displaying camera... 

Honey Encryption (HE) has been introduced to provide resilience for cryptographic algorithms with low min-entropy keys, against brute-force attacks. Using spurious keys, we have designed an encryption framework consisting of a Distribution Transforming Encoder (DTE), which uses a Password Based Encryption (PBE) algorithm in CTR mode of operation. The proposed DTE block benefits from an efficient error-correcting code, acting as a many-to-one mapping scheme. The proposed framework gets some spurious key-plausible looking plaintext tuples as input and outputs a ciphertext. The structure of the proposed scheme is designed to increase the uncertainty of attacker about the correct plaintext, even... 

Acceleration of the universe is one of the most challenging conundrum of contemporary physics. One of the leading approach to this conundrum is introducing a new component in Einstein’s equations which is called the dark energy. Dark energy models which their’s dynamics are dictated by holographic principle, are called holographic dark energy. Essentially,the constraint implied by the holographic principle is a macroscopic constraint. In consequence, the constraint gives no informations about microscopic aspects of dark energy. To understand the nature of the holographic dark energy, we need a microscopic theory from which we can extract the behaviors of holographic dark energy. It can be... 

By entering the concepts of transactive energy systems, microgrids and peer-to-peer networks into the local energy market, it has made it possible to implement local energy market in the microgrids more than ever. In transactive energy systems, with the elimination of the intermediate entity, exchanges take place directly between the different parts of the system, which results in increased system flexibility and reduced system costs. In this study, by applying blockchains in local energy market and in micro-grids and transactive energy systems, a framework is proposed to implement local energy market in an energy micro-grid based on blockchain. By using blockchain features and structure,... 

An aerial structure can be at the disposal of the owners of damage or intellectual property during its lifetime, under the supervision of static and dynamic loads and providing information in the field of recognizing temperature, humidity and environmental pressure with high-speed gradient. Capable Composite patches are used to repair damaged areas. Composite patches have unique properties such as high strength to weight ratio and corrosion resistance. In structures modified with a composite patch, various failures occur during loading, including: fiber breakage, matrix fracture, separation of fibers from the matrix or the latest patch from the main structure and failure of the metal... 

In this thesis, the bidding strategy of prosumers in transactive energy markets is analyzed. Considering the repaid increase in utilizing installations that convert multiple energy together, the concept of multi-carrier energy studies has been highlighted. Moreover, with the advent of district heating networks, thermal energy markets have gained much attention lately. The agent who participates in such markets can appropriately benefit from the inherent interdependencies between various energy carriers depending on their prices in different energy markets. This market player is technically called to pose an energy hub. In this regard, to deploy the inherent abilities of such an energy... 

The issue of loss allocation is one of the most important issues that has long been considered in electricity networks, including distribution and transmission. With changes in distribution networks over the years and the penetration of distributed energy sources, the allocation of losses has become more of a challenge than ever before. Hence, there is a need for a loss allocation algorithm that can be implemented in any network and with any topology. In this dissertation, a new, simple and at the same time efficient algorithm for allocating real losses in all networks (distribution - transmission) and with any structure (radial - circular) is presented. This algorithm first tracks the... 

Using energy storage systems has been remarkably improved the energy systems efficiency and reliability indicators of the system and also reduced the operating costs of these systems. Thus using them in an energy system would count as an advantage. Lately, the procedure of implementation of these systems has been studied widely and various motives behind implementing them have been reviewed. For example, the effect of cost optimization in electrical vehicles on reliability indicators from the load management perspective can be addressed. Therefore this thesis has studied the effect of electrical and thermal storage systems on the reliability indicators of an energy hub and the effect of...