Sharif Digital Repository

The purpose of this research is to investigate the impact of human capital on the performance of startups in Iran so that its findings can be used to guide the startups and companies, policymakers, and entrepreneurs. According to a study by Aguin andcolleagues. (2009), the establishment of new firms through entrepreneurial activities can increase national economic growth, creativity and productivity at the national level. Joseph, in 1995, stated in an article what has been pointed out by some researchers in the field of entrepreneurship in developing countries, Programs and strategies that succeed in a country will not necessarily succeed in another country, due to cultural and governmental... 

Software Defined Networking (SDN) is an emerging paradigm which makes the network programmable by separating the control plane from data plane and makes both planes to work independently. There is a centralized controller and a programmable data plane in these networks architecture and forwarding data packets is realized by programming the data plane via an open interface called OpenFlow. OpenFlow is a communication protocol between control and data planes. The centralized architecture of these networks provides a global view of the underlying network to upper applications and brings numerous advantages such as routing, traffic engineering and QoS control. Despite these advantages there are... 

The increasing gap between performance of Hard Disk Drives (HDDs) and processors has made storage subsystem as the performance bottleneck of computer systems. Solid-State Drives (SSDs) due to having no mechanical parts provide higher performance compared to HDDs. However, the high price of SSDs compared to HDDs prevents them from replacing HDDs. Employing SSDs as a caching layer for HDDs is a cost-efficient solution for designing high-performance storage subsystems. Previous studies on SSD caching neglected to simultaneously consider performance, endurance, and reliability in their architectures. In this thesis, Three-level I/O Cache Architecture (TICA) is proposed, which tries to improve... 

Non-Volatile Memories (NVMs) are emerging storage devices with promising characteristics such as low static power consumption, high performance, and non-volatile property to keep the stored data in the absence of power supply. Despite such interesting characteristics, NVMs suffer from high dynamic power consumption and limited lifetime. These limitations prevent NVMs from directly replacing the existing storage devices without any refinement in the architecture of computer systems. In this dissertation, we first investigate the characteristics of emerging NVMs and offer effective architectures to improve the efficiency of computer systems at the Operating System (OS) level. The main aim of... 

With the rise of the concept of “Big Data”, both data volumes and data processing time increased, imposing the need for new methods of processing and computation of said data.Analytical and computational methods in Machine Learning are some of the most important applications of Big Data processing. There exist many methods of data analysis in the Machine Learning field, each requiring extensive processing on Big Data. One of the methods for working with Big Data is Distributed Systems. MapReduce is one of the most popular methods distributed computation by increasing the ease and speed of distributed processing of big data. But a number of bottlenecks have been discovered in MapReduce which... 

Data Prefetcher is a central component in most processors. Different methods have been proposed with varying degrees of complexity and effectiveness. Recent research revisits pairwise-correlating data prefetching due to its extremely low overhead. Pairwise-correlating data prefetching, however, cannot accurately detect where data streams end. As a result, pairwise-correlating data prefetchers either expose low accuracy or they lose timeliness when they are performing multi degree prefetching. In this work, we propose a novel technique to detect where data streams end and hence, control the multi-degree prefetching in the context of pairwise-correlated prefetchers. The key idea is to have a... 

In recent years, GPUs are becoming ideal candidates for processing a variety of high performance applications. By relying on thousands of concurrent threads in applications and the computational power of large numbers of computing units, GPGPUs have provided high efficiency and throughput. To achieve the potential computational power of GPGPUs in broader types of applications, we need to apply some modifications. By understanding the features and properties of applications, we can execute them in a more proper way on GPUs. Therefore, considering applications’ behavior, we define 5 different categories for them. Every category has special definitions, and we change the configuration of GPU... 

Considering current problems in performance evaluation of the Cloud and its management policies and strategies, this thesis presents different approaches for simultaneous evaluation of the performance, dependability, and power consumption of Infrastructure-as-a-Service (IaaS) clouds. The proposed approaches use Stochastic Reward Nets (SRNs) and Stochastic Activity Networks (SANs) to model and evaluate performability and power consumption of cloud systems. In all of the proposed approaches, the cloud resource management system is power-aware. It means that idle Physical Machines (PMs), network equipment, and supporting subsystems are kept in powered-off or standby modes, as much as possible,... 

The vanadium redox flow battery (VRB) is a promising solution for storing renewable energy, such as wind and solar energy and promising for replacing these energies with fossil energies. Since a great proportion of a current battery cost is due to the presence of a nafione membrane in the middle of the battery cell, the membrane removal reduces the cost of these batteries. In this project, a single cell membrane-less flow battery in discharge mode has been simulated by COMSOL software. In order to remove the membrane from this battery, a Y-shaped microchannel, lateral faces containing thin porous film which act as anode and cathode, has been used. The small size of the channel and low... 

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... 

Processing of large graphs is the key component in many data analytics applications.We model the relationship of entities in different applications, such as web page ranking, social networks and tracking drug interaction with cells, using graphs. Graphics processing unit (GPU) is a well-known accelerator used for graph processing. Unfortunately, there are many challenges for mapping graph applications to GPUs efficiently. As graph applications have more kernel invocations and data transfers, using caches in these applications would be ineffective. Since vertices’ degrees of a graph are different, load distribution in many graph applications is not well balanced.Recently, matrix algebra has... 

Mergers and acquisitions are one of the easiest and sometimes the only way to stay in the market for small or low performing companies. In this research, which consists of two main parts, the impact of merger and acquisition on the stock price and financial statements of the involved companies that were listed in Iran stock exchange market was studied between 2007 and 2012.The first step, through an event study, abnormal stock returns of the targeted companies were studied in time spans of five and ten days before and after the merger and acquisition event. Then a t test was applied in order to examine whether this transaction had resulted in positive abnormal return for the shareholders or... 

Solid State Drives (SSDs) have an electronic architecture based on non-volatile memories. The unique merit of a SSD is its internal parallelism. Thus, adopting SSDs as the storage media in the storage systems in various devices, such as smart phones, personal computers, large workstations, and etc., improves the performance of the device, substantially. However, the conventional host interface protocols in SSDs, i.e. SATA and SAS, have critical limitations, like low bus bandwidth (maximum 12Gbps), and a single shared request queue. With such limitations, the host interface turns into a performance bottleneck in conventional SSDs. Therefore, the high performance provided by such SSDs cannot... 

Business intelligence is a set of theories, methods, processes and technologies that are used to obtain useful and meaningful information. Due to the inclusion of different and various products, chain stores have to manage a lot of data, which is different from the retail and company data in terms of number and variety. in this regard business intelligence has to be used for making decisions. The catch is felt in different parts of the chain stores. The main purpose of this study is to provide a model to investigate the impact of using business intelligence on Ofogh Kourosh chain stores. Research variables were extracted using literature review on the impact of business intelligence on chain... 

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... 

Due to reduced Non-Recurring Engineering (NRE) costs, shorter time to market, design flexibility, and reprogramming capability of Field-Programmable Gate Arrays (FPGAs) as compared to Application-Specific Integrated Circuits (ASICs), FPGAs has been raised as a suitable substrate for implementation of digital systems. However, the high flexibility of reconfigurable devices leads to great power consumption, chip area, and reliability difference between ASICs and FPGAs. In addition, with the advent of multi-tenant FPGAs in cloud computing environments, it has been shown that crosstalk side-channel attack, which can be used by a malicious IP to leak valuable information, has become an urgent... 

This thesis analyses the relationship between performance and capital structure of listed companies in the Tehran stock exchange. For examining this relationship, we use trade-off theory. This theory states that using debt comes with some benefits and costs for the company. If this theory holds true, we expect that in a low debt capital structure, as a result of benefits of using debt surpasses the costs of it, the relationship between debt and performance should be positive and in a high debt capital structure, as a result of costs of using debt surpasses the benefits of it, using more debt should have negative relationship with performance. For examining this relationship, we first gather... 

The lifespan of hard disks greatly affects their performance and reliability. Ensuring the freshness of disks during the procurement process for hardware manufacturing companies is crucial for maintaining efficient production systems. Predicting the approximate lifespan of hard disks involves analyzing their characteristics and operational history. Relying solely on SMART reports for estimating disk lifespan is not reliable due to the potential firmware tampering. Previous studies have primarily focused on SATA disks, investigating the relationship between failures and SMART parameter values, while neglecting SAS disks. However, in this research, we collected SMART reports from approximately...