Sharif Digital Repository

Hybrid vehicles have many advantages, including reducing greenhouse gas emissions, saving fuel, and optimizing energy use. Proper routing for hybrid vehicles can improve fuel efficiency, increase energy efficiency, and even extend the life of electric batteries. In this study, two routing modes, offline and online, are introduced. The offline mode guides the vehicle from the starting point to the destination by using satellite traffic data and geological information such as slope information. In the online mode, the vehicle, with the ability to receive signals from surrounding vehicles (V2V), such as a breakdown of the vehicle in front, and considering concepts such as traffic, the presence... 

Energy storage systems are expected to play an important role in future renewable-based power systems. Recently, lithium-ion batteries have been attracting considerable attention as alternative energy storage systems due to their advantages. In this study, viability of battery storage systems as large-scale energy storage systems is studied in the context of a residential energy hub. A stochastic optimization problem is proposed for energy management of the energy hub where wind generation and demand are considered uncertain. In order to account for the degradation costs of the battery storage system, a data-driven State-of-health prediction model is developed based on the relevance vector... 

A virtual power plant is defined as a set of independent consumers or diverse generating units, flexible loads and storage systems in a specific geographic area. The primary purpose of a virtual power plant is thus to coordinate the production and consumption of its constituent parts with a view to maximizing their performance in energy markets. The components of the virtual power plant that study in this research include microturbines as dispatchable power plants, storage units, solar cells as stochastic generating units, and demand-response. In this regard, first, the main components of the virtual power plant are identified. Then, the mathematical model of each of these components is... 

Occurrence of natural disasters such as flood, windstorms, tsunamis and earthquakes has caused striking effects on critical infrastructures like power systems in recent decades. There are some examples of high-impact low-possibility (HILP) events which causes catastrophic effects on power systems. Traditionally, planning and operational studies of power system have been run taking into account some reliability metrics. Although, the reliability indices can represent the ability of a system in confronting with possible failures of components, they are unable to efficiently consider the effects of severe events such as earthquake and other HILP events. Moreover, traditional power systems were... 

The study of heat transfer using solid-liquid phase shifting has attracted much attention in applied engineering fields such as latent heat energy storage, building walls, waste energy recovery, battery thermal management, and more. Over the past few decades, the literature on phase shift has grown tremendously in terms of theory, laboratory, and numerical studies. Melting of phase change materials in rectangular chambers due to its wide range of engineering applications in fields such as casting, metallurgy, heat energy storage, and heat exchangers used in buildings, as well as aerospace issues including the use of These systems have been the subject of numerous studies on space missions to... 

Nowadays, design and development of high performance storage subsystems have been a crucial step in data-intensive computer systems. One of the solutions for improving the overall performance of data storage systems is to use emerging flash-based memories as an I/O cache. OpenCAS, EnhanceIO, and DM-cache are well-known I/O cache modules with different architectures. None of the previous works studied the performance of these I/O cache modules in detail. This research evaluates the performance of I/O cache modules under the real and synthetic workloads and tries to analyze the observed behavior based on their high-level architecture. In addition, we propose some insights about how to improve... 

The increasing growth of digital data and the use of data-intensive applications and cloud computing have made data storage systems the performance bottlenecks of computing systems. To improve the efficiency of data storage systems and enhance the quality of service, storage system manufacturers use high-performance storage devices such as solid-state drives (SSDs) in their designs, namely, all-flash storage systems. SSDs provide significant performance compared to hard disk drives and are used in the architecture of high-speed storage systems. Despite very high speed of SSDs, their high price and low endurance have limited their usage in data storage systems. The limited endurance of SSDs... 

Quality of Service (QoS) has recently become one of the most important challenges in data storage systems due to the growing use of data intensive applications in enterprise and mainstream systems. Flash-based Solid-State Drives (SSDs) are high-performance storage devices used in data storage systems to fulfill the performance demands of different applications using shared data storage system. Flash-based storage systems have limited endurance and poor write performance, resulting in quality of service issues such as unfairness. Different techniques such as I/O caching can be used to address QoS in storage systems but they adversely affect system endurance. To our knowledge, previous studies... 

In recent years, high interest in using virtualization platforms and Virtual Machines (VMs) in enterprise data centers and Clouds has significantly increased the demand for high performance data storage systems. Recent studies in virtualized platforms have suggested using high-performance storage elements such as Solid-State Drives (SSDs) as a caching layer for storage subsystems mainly built upon Hard Disk Drives (HDDs). Such studies implicitly focus on sharing and partitioning the I/O cache space between VMs, while they neglect to address other important parameters such as SSD lifetime, reliability, and cache policies, which can significantly affect the efficiency of I/O caching in terms... 

Due to the increasing use of data storage systems and volume of digital data, fast information access and retrieval has significant effect on performance of storage-bound systems. Operating systems utilize the spare space in the main memory as a cache to speed up access to the storage subsystem. Due to the large performance gap between hard disk and main memory, any improvement in this caching layer can greatly affect the performance of the entire system. Page replacement algorithms are one of the important mechanisms in the virtual memory management layer. Several algorithms have been proposed for the eviction of pages from the virtual memory cache and few of them have also been implemented... 

As a new technology, the use of Solid State Disk (SSD) in storage systems is increasing due to its higher performance and lower power consumption as compared to the traditional Hard Disk Drive (HDD). On the contrary, the SSD technology has two serious shortcomings, i.e., 1) it has a higher Bit Error Rate (BER) as the number of Program/Erase (P/E) cycles increases, and 2) it can endure a specific number of P/E cycles, called the write endurance limitation. To overcome the endurance limitation of SSDs, several solutions have been proposed in previous literature. These solutions can be categorized in two levels: 1) SSD-controller, and 2) RAID–Controller. Moreover, it is necessary to consider... 

The use of flash-based Solid State Disks (SSDs) has been increased in the past decades because of their high performance and low power consumption. As SSDs have no moving mechanical parts, they are more reliable than HDDs. SSDs have specific errors, such as read, program, and erase disturbs, data retention, and endurance. It is so common in storage systems to apply an array of disks called Redundant Array of Independent Disks (RAID) together for the aim of reliability and performance. Erasure codes are one of the main methods applied in storage systems for the aim of reliability. Erasure codes increase the reliability of storage systems by protecting them against disk failures and sector... 

In recent years, improving the energy efficiency of Hard Disk Drives (HDDs) in enterprise data storage systems has been of great attention for system designers.Recent studies have demonstrated that storage devices contribute up to 27% of the total energy consumption in data centers. One approach to improve the energy efficiency of HDDs is to bring a disk working state to standby mode when there is no request for HDDs. This can be achieved by reducing the number of requests sent to HDDs by employing global memory and prefetching data blocks from HDDs to this memory in advance. Employing prefetching techniques can improve both system performance and energy efficiency. While aggressive... 

Performance and reliability are the major concerns in design of data storage systems. Using Redundant Array of Independent Disks (RAID) can enhance both performance and reliability. A commonly used configuration in RAID arrays is erasure codes to further enhance system reliability. Due to promising advantages of Solid-State Drives (SSDs)such as low power, shock resistance, and high I/O performance, designers have been encouraged to replace Hard Disk Drives (HDDs) by SSDs in RAID arrays. SSDs, however, suffer from limited endurance due to erase-before-write operation.In this thesis, we investigate the effect of stripe unite size and the number of disks of a RAID array on the endurance of SSDs... 

The increasing size of valuable data emphasizes the importance of applying reliability in storage systems. One way to protect storage system failures is using erasure codes. The advantages of using erasure codes are their low overheads and high reliability. Soft errors caused by high-energetic particles do not only corrupt data in the SSD-based storage systems, but also in the erasure codes. In this regards, it is important to protect erasure code implementations against soft errors. This thesis proposes a fault-tolerant implementation of erasure codes. The proposed method is based on the structure of each erasure code. This method is analytically evaluated on four erasure codes, i.e.... 

Nowadays, enterprise storage systems are widely used in data centers such as databases, servers, and bank institutes. Due to mechanical activity of disk drives, these systems are one of the most power consumptive components in data centers. Prefetching and RAID, which are employed to enhance performance, are widely used in data storage systems. These two methods, however, impose significant energy overhead to the system due to the increased disk activity. In this thesis, we first elaborate shortcomings of prefetching and RAID methods. Then, we propose a new energy efficient and RAID-compatible prefetching method (LPTAP), which aims at improving performance and energy consumption. To evaluate... 

In this study, a vapor-compression cooling system utilizing different PCMs has been studied whereby the electricity consumption peak load is shifted. More specifically, the dynamic performance of cooling systems with and without using PCM is evaluated for the hottest day of the year. The proposed system uses the cooling energy to freeze, or “discharge” the PCM during nighttime when the cooling load is minimally needed and uses the stored thermal energy during the peak load hours by melting, or “charging” the PCM. This leads to better performance during peak load hours when higher cooling loads are needed. Different PCMs including Oleic acid, SP224A, CL, CaCl2.6H2O have been investigated. The... 

Energy conversion and storage as well as life sciences are among the areas of our daily life. Interest in carbon nanomaterials for energy storage systems such as supercapacitors has enormously risen due to their attractive electrical conductivity, chemical inertness, and charge storage capacity. Producing these nanomaterials with a simple, scalable, and cost-effective method is the major problem for commercializing them. The reduction of graphitic oxide is a versatile procedure to prepare 3D graphene. Despite many green methods, the dynamics behind ultrafast thermal graphitization have remained elusive. Here, we demonstrate an effort to understand the graphitization mechanism of graphitic... 

Smart grids enable the implementation of novel energy management schemes for network operators. The restructuring of the power grid and the smartening of consumers, in addition to addressing environmental issues faced by traditional networks, have enabled many capabilities in the power grid, such as increasing network flexibility, peak shaving, and slowing down equipment obsolescence. The use of novel schemes, however, comes with its own set of challenges. One of these challenges is the uncertainty in the network, particularly on the supply and demand sides. Another challenge is the level of consumer engagement in energy management schemes. In this research, which is based on energy sharing,... 

Recent widespread blackouts around the world have highlighted the fact that power grids must not only ensure reliability against high-probability, low-impact events (HPLI), but also against low-probability, high-impact events (HILP) such as earthquakes, hurricanes, and hurricanes and resist against unnatural events such as cyber attacks. On the other hand, transformation of traditional electricity distribution systems into smart networks that have the ability to automatically perform switching and fault locating can enable utilities to minimize operational costs in case of HILP events occurences. Although the use of distribution automation has been suggested as one of the smart grid...