Sharif Digital Repository

Significant increase of static power with downscaling of transistor feature size and threshold voltage has lead to the end of Dennard scaling. This obstacle has put a Power Wall to further integration of CMOS technology in Field Programmable Gate Arrays (FPGAs). An efficient solution to cope with this obstacle is to apply power gating to the inactive fractions of a single die, referred to as Dark Silicon. Previous studies employing power gating on SRAM-based FPGAs have primarily focused on using large-input Look-up Tables (LUTs) which suffer from poor logic utilization, and subsequently, limiting the benefits of power gating techniques. This thesis proposes a heterogeneous Power-Efficient... 

Emerging Solid State Drives (SSDs) have performance advantages over traditional Hard Disk Drives (HDDs). Higher price per capacity and limited lifetime, however, prevents enterprise data centers to entirely replace HDD-based storage subsystems with SSDs. Thus,SSD-based caching has been widely employed in data centers to benefit from higher performance of SSDs while minimizing overall cost. Input/Output (I/O) workloads exhibit unpredictable and highly random behavior which makes conventional algorithms such as Least Recently Used (LRU) not able to provide high hit ratio as they employ linear localities.In addition to poor performance, such algorithms also shorten SSD lifetime with unnecessary... 

Formality style transfer, in other words, automatic transfering style of informal text to formal and vice versa, means changing the style and form of a sentence without changing its content. With the increasing progress of deep neural networks, the formality style transfer in other languages has attracted the attention of other researchers and has made significant progress in natural language processing tasks. Due to the availability of parallel data in the English language, the task of style transfer has been approached and designed basically in the framework of the "encoder-decoder" architecture of neural networks. However, due to the lack of parallel datasets in the Persian language, this... 

In recent years, dust pollution has become a worldwide issue due to the creation of serious environmental problems and the effects it has on human health. In this research, an environmentally friendly soil stabilizer has been synthesized, and its performance has been investigated. Acrylamide monomers were grafted onto sodium lignosulfonate chains, utilizing solution polymerization. The soil of the Ahvaz deserts was used in the analyses. Using EDX and DLS analyses, the components of this soil and the particle size distribution of the used soil were obtained. Characterization of the functional groups and the structure of the graft copolymer were done by FTIR and H-NMR analysis, respectively,... 

The purpose of this research is to monitor the health of structures using the updated finite element model, in which digital images are used to optimize the numerical model. Structural Health Monitoring (SHM) is always an important and significant issue that has attracted the attention of many researchers in recent years. In general, some researches have been conducted in this field using physical sensors that provide discrete data to the system for analysis. Using cameras to monitor the structure makes it possible to extract continuous and integrated data from the structure using digital images, which is a significant advantage compared to physical sensors.In this research, a steel... 

Study of the structural flexibility of large-scale wind turbine components on aeroelastic performance is important under the existence of critical atmospheric conditions. Prediction and control the critical deformations, identifying maximum local deformation and modeling the forces involved, are required. Aeroelasticity analysis is a suitable method for studying the coupling effects of wind turbine aerodynamics, dynamics and structures. This research has been done by modeling wind turbine components including blades, hub, nacelle and tower, taking into account aerodynamic couplings, dynamics and structures. Considering the large scale of reference wind turbine, nonlinear equations have added... 

Aluminum Bronzes have many applications in marine environments. These alloys suffer from both hot cracking and cold cracking. In order to overcome the hot cracking and cold cracking, Semisolid Stir Joining method and a proper thermal cycle was used respectively. Effects of temperature, stirring rate, and tool type were investigated in Semisolid Stir joining method. In this method, butt joint design was used in order to place specimens, and the specimens were heated up to specific temperatures (920, 925, 930°C). A stirrer (Cylindrical and Grooved tool) with three rotational speeds (800, 1200, 1600 RPM) was introduced into the stir weld seam. Welded specimens were cooled to the 900°C... 

Gas liquefication in low temperatures is one of the most challenging fields in engineering due to complexity of its thermodynamic analisys and fabrication of equipments. Heat Exchangers are one of the most important equipments in these prosseces. High prices of Heat Exchangers in these facilities makes their Optimal and cost effective design, of crucial importance. In this thesis three dimensional model of a Plate Fin Heat Exchanger is thoroughly investigated. Fistly, by means of Aspen Heat Exchanger design Software a counter flow Heat Exchanger is designed. This HX is to be placed in Collins cycle, so, working fluid in both hot and cold streams is Helium Gas. The HX then by means of ANSYS... 

In order to increase the network performance, to discover network security threats, to guarantee the quality of services, to simulate networks and develop new network protocols, network designers and operators need software tools to analyze the network traffic. The first step to do this analysis is network monitoring. This can be done by using various software and hardware tools.
In this research we developed a tool which analyzes the network traffic using appropriate statistical methods. The models which are analyzed in this application are: Poisson, Self-similar and Weibull. This application analyzes the network traffic based on this statistical models and calculates their parameters.... 

The increasing number of road accidents and fatalities have yielded the introduction of several solutions by related industries such as automobile manufacture. Proposed solutions can be classified into two categories: passive, such as airbags, and active such as ABS ad ITS-based technologies. Inter vehicles communication let the communication between vehicles(V2V) or between vehicles and road infrastructure (V2I) by relying on DSRC technology and standards. Intelligent Transportation System (ITS) has three main types of applications namely safety, traffic and commercial. Safety applications are the main goal of vehicular communication, and real time guarantee in safety applications is so... 

Nowadays, one of the problems of network designers and users is the correctness of network equipment functionality. Since routers play an important role in information transfer between various networks and communicate with each other through a routing protocol, any violation of such protocol can result in the network's failure or defective transfer of data. Thus, being assured of the conformance of the implemented protocol in a router with what has been defined in the protocol's standard is of great significance. To this end, before using or exposing a router, network equipment testers should run protocol conformance tests on it and insure its correct functionality. This brings up the... 

In real-time systems, jobs that miss their deadline are considered worthless or ineffective. Nowadays, real-time applications (such as multimedia) that communicate through software-defined networks (SDN) are widely used and will continue to expand in the future. SDN is an emerging network architecture in which control plane is separated from data plane to manage it directly. In this research, we make changes to the controller and the switch used in such network to deliver real time packets or real-time flows (such as video) on time, as much as possible. As missed deadline packets are worthless and they waste bandwidth, dropping them is a solution. Moreover, the controller can drop flows that... 

Network Function Virtualization (NFV) is a new paradigm in computer networks for implementing network functions on general-purpose common-of-the-shelf processors. The revolutionized NFV architecture has shown to be a suitable replacement for hardware middleboxes. NFV is in high demand because of its lower costs, increased flexibility, and more scalability. However, the ever-growing volume of network traffic and increased data transfer speed in computer networks have made achieving high performance the major issue in this area. With thousands of processing cores and high memory bandwidth, Graphical Processing Units (GPUs) are potentially an appropriate solution to accelerate network... 

Recent advancement in wireless communications, electronics, low power design and also tendency to use high performance low cost products have led to emergence of Wireless Sensor Networks (WSNs). As the main purpose of a WSN is information gathering and it’s transmission to the sink node, the main problem is to deliver information correctly with minimum energy consumption. Besides, whereas the majority of developed applications for WSNs are event-critical applications, achieving reliable data transfer as the main factor of dependability and quality of service seems vital. However, data transmission is unreliable over multi-hop WSN due to the unreliability of wireless links and node failures. ... 

In this research, Friction stir welding (FSW) of 7075-O and 7075-T6 aluminum alloys was performed to investigate the effects of the base material conditions, effects of process parameters on the FSW characteristics and optimum parameters which lead to best mechanical properties of joints. The experimental results indicated that the base material condition has a significant effect on weld morphologies, weld defects, and mechanical properties of joints. The optimum parameters were 1230 rpm and 60 mm/min for 7075-O and 1230 rpm and 100mm/min for 7075-T6. Also, Double welded friction stir welding of 7075 aluminum alloy was performed to investigate the effects of the second pass of weld on the...