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A failure control method for smart composite morphing airfoil by piezoelectric actuator
, Article Transactions of the Canadian Society for Mechanical Engineering ; Volume 35, Issue 3 , 2011 , Pages 369-381 ; 03158977 (ISSN) ; Zabihollah, A ; Sharif University of Technology
2011
Abstract
In this paper, a nonlinear Finite Element (FE) approach based on the layerwise displacement theory is utilized to obtain the interlaminar stresses due to buckling phenomena in unsymmetric laminated smart composite morphing structure. An On/Off control strategy is designed to control the snap-through phenomena. Due to cycling nature of applied load on morphing, these structures are vulnerable to failure due to fatigue. A failure control mechanism utilizing a piezoelectric actuator is developed to control the failure
A semi-active SMA-MRF structural stability element for seismic control in marine structures
, Article Applied Ocean Research ; Volume 100 , 2020 ; Zabihollah, A ; Sharif University of Technology
Elsevier Ltd
2020
Abstract
The stability and integrity of structures under indeterminant external loadings, particularly earthquakes, is a vital issue for the design and safe operation of marine and offshore structures. Over the past decades, many structural control systems, such as viscous-based systems, have been developed and embedded in marine and offshore structures, particularly oil platforms to maintain the stability and mitigate the seismic hazards. Rapid improvement in intelligent materials, including shape memory alloys (SMAs) and Magnetorheological fluid (MRF), have led to the design and development of efficient structural control elements. The present work aims to establish a framework for the structural...
A study of pre-straining shape memory alloy (SMA)-based control elements subject to large-amplitude cyclic loads
, Article Ships and Offshore Structures ; 2020 ; Zabihollah, A ; Sharif University of Technology
Taylor and Francis Ltd
2020
Abstract
Dynamic environmental loads, such as winds and waves, make the stability of offshore structures at high risk, requiring reliable yet efficient control elements to ensure the stability of such structures under lateral loads. Among the variety of control elements that have been developed to enhance the stability of a structure, shape memory alloy (SMA)-based control elements are promising as they are low-cost, easy to embed into the main control element, and do not need an external power supply. However, cyclic loads may highly influence the performance and functionality of SMA-based elements. The present work investigates the effects of pre-straining SMA components in energy dissipation...
Failure and Buckling Control of Smart Morphing Composite using Nonlinear Finite Element Method
, M.Sc. Thesis Sharif University of Technology ; Zabihollah, Abolghasem (Supervisor)
Abstract
Structures that change shapes are often called morphing structures. Smart morphing composites refer to the morphing structures that can detect the change in conditions and, through a control mechanism, command the actuators to maintain the stability and/or perform a new task. The present report provides a framework on the eld of smart morphing composite structures. The emphasis on this work is on, particularly, multi-stable composite structures with capability to detect the new conditions and adapt themselves to properly respond to them. Due to cycling nature of applied load on morphing, these structures are vulnerable to failure due to fatigue. A failure control mechanism utilizing a...
Buckling control of morphing composite airfoil structure using multi-stable laminate by piezoelectric sensors/actuators
, Article Proceedings of SPIE - The International Society for Optical Engineering, 7 March 2011 through 9 March 2011, San Diego, CA ; Volume 7978 , 2011 ; 0277786X (ISSN) ; 9780819485403 (ISBN) ; Zabihollah, A ; Azizi, A ; Sharif University of Technology
2011
Abstract
In the present work, an unsymmetric laminated plate with surface bonded piezoelectric sensors, and actuators has been considered. Piezoelectric sensor were used to monitor the load and deformation bifurcation occurs. Monitoring the shape and load of a morphing structure is essential to ascertain that the structure is properly deployed and it is not loaded excessively, thus, preventing structural to failure. A piezoceramic actuator is used to provide activation load and to force the structure to change its stability state from one to another. A non-linear finite element model based on the layerwise displacement theory considering the electro-mechanical coupling effects of piezoelectric...
Vibration monitoring of wind turbine blade using fiber bragg grating
, Article Wind Engineering ; Volume 34, Issue 6 , 2010 , Pages 721-731 ; 0309524X (ISSN) ; Zabihollah, A ; Zareie, S ; Sharif University of Technology
2010
Abstract
Rapid growth in generating power from wind turbines led to application of long laminated composite blades. However, as the length of blades increases, the risk of failure due to excessive vibration increases. Therefore, a reliable wind power generator requires an efficient and accurate, yet economical structural health monitoring system to detect vibration and apply a reliable control to prevent from unpredicted failure. This paper presents an optimal, low cost and continuous vibration monitoring system for laminated composite blades using Fiber Bragg Grating (FBG). Utilizing a layerwise displacement theory, the Finite Element (FEM) model has been developed for the wind turbine blade. The...
Optimization of Forging Processes with Concurrent Approach
, M.Sc. Thesis Sharif University of Technology ; Hosseini Kord Khyli, Ali (Supervisor)
Abstract
With the increasing complexity of manufacturing processes and the interrelations between the different phases, the possibility of a phase being affected by a preselected desing variable is very high. In that case, the influence of a desing variable not only on the part performance of but also on the feasibility and efficiency of its manufacturing should be considered. Concurrent engineering approaches should then be adopted to take the control of such complicated relations among the subprocesses. In this thesis a concurrent design optimization methodology was proposed to minimize the cost of a cold forged manufacturing process using the design parameters as optimization variables. An...
Hierarchical Optical Network-on-Chip Based on Hypercube Topology
, M.Sc. Thesis Sharif University of Technology ; Hesabi, Shahin (Supervisor)
Abstract
According to prediction of ITRS, power consumption and bandwidth of processors' interconnection, will be the most major bottleneck of the System-on- Chips (SoCs) in the future. Therefore, in MultiProcessor System-on-Chip (MPSoC) architectures, the design constraints will be altered from "Computational Constraints" to "Communicational Constraints". There are three kinds of communications in the surface of the chip: Global, median and local. The main difference between global and local connections is that the length of latter one will be changed with technology. In other words, it is scalable like processor's elements while the length of global connections is practically constant. Even though...
Architecture of Reconfigurable Optical Network-on-Chip
, M.Sc. Thesis Sharif University of Technology ; Hesabi, Shahin (Supervisor)
Abstract
According to power limitation on a chip and the need to simultaneously access high utilization and low power consumption, Multi-Processor System-on-Chip (MPSoC) architectures have been introduced. The major part of power consumption in a network on chip belongs to interconnects. One of the most important issues is to decrease power consumption while maintaining high utilization. The ability of optical interconnects in decreasing power consumption and increasing utilization has introduced a new architecture called optical network on chip. This architecture uses the benefits of optical signals and elements in order to transfer data. In this thesis, we introduce a new architecture with...
Analysis of Off-Critical Percolation Clusters by Schramm-Loewner Evolution
, M.Sc. Thesis Sharif University of Technology ; Rouhani, Shahin (Supervisor)
Abstract
Recently, a new tool in the study of two-dimensional continuous phase transition was provided by Schramm-Loewner evolution. The main part of SLE is a conformal map which relates growth process of a two-dimensional simple curve to one-dimensional motion on the real axis (so-called Loewner driving function). Time evolution of this map and Loewner driving function is connected via the Loewner differential equation. It turns out that for a certain class of stochastic and conformally invariant curves in two dimensions, the driving function shows Brownian motion in one dimension. Strength point of SLE comes from this fact that all the geometrical properties of such curves is described through a...
The Watershed Model and Schramm-loewner Evolution
, Ph.D. Dissertation Sharif University of Technology ; Rouhani, Shahin (Supervisor)
Abstract
Schramm Loewner evolution (SLE) is a one-parameter family of random simple curves in the complex plane introduced by Schramm in 1999 which is believed to describe the scaling limit of a variety of domain interfaces at criticality. This thesis is concerned with statistical properties of watersheds dividing drainage basins. The fractal dimension of this model is 1.22 which is consistent with the known fractal dimension for several important models such as Invasion percolation and minimum spanning trees (MST). We present numerical evidences that in the scaling limit this model are SLE curves with =1.73, being the only known physical example of an
SLE with <2. This lies outside the...
SLE with <2. This lies outside the...
Energy Efficient Concurrent Test of Switches and Links for Networks-On-Chip
, M.Sc. Thesis Sharif University of Technology ; Hessabi, Shahin (Supervisor)
Abstract
Nowadays by increasing the number of processing cores in system-on-chip, using networks-on-chip, as an optimized interconnection foundation for transferring data between processing cores is inevitable .Based on this, the necessity of designing and implementing an optimized structure for testing network-on-chip, considering various overheads such as power consumption, latency, bandwidth and area, becomes an important issue in designing network-on-chip. The purpose of this project is to design an optimized structure for testing routers and connecting links in network, which considers power consumption overhead, latency and area overhead on one hand, and fault coverage on the other hand....
High Speed CDMA Communication in Optical Network on Chip
, M.Sc. Thesis Sharif University of Technology ; Hesabi, Shahin (Supervisor)
Abstract
As the number of processing cores on a single chip continues to grow, the need for a high band width, low power communication structure, will be the most important requirements of next generation chip multiprocessors. Today, a major part of power consumption in multi core architectures belongs to interconnects. Due to these facts, reducing consuming power, as well as supporting high performance, is concerned in these architectures. The concept of “network-on-chip” emerged to improve the performance of CMPs. But now a day, considering the circumstances of power budges, it’s incapable of presenting new strategies to decrease consuming power and delay. However, optical interconnects have the...
Modified WK-Recursive Topology for an Optical Network-on-Chip
, M.Sc. Thesis Sharif University of Technology ; Hesabi, Shahin (Supervisor)
Abstract
Nowadays, a large proportion of the power consumption in high-performance multi-processor architectures on chip belongs to connections. Reducing power consumption while maintaining high efficiency in these architectures is one of the main concerns. Networks on Chip (NoC) originally were introduced to improve efficiency, but now, given the importance of power, we must provide some solutions to reduce power consumption, and delay in NOCs. Connections in chip can be divided into three categories: global, intermediate and local, while the length of global connections is almost constant in different scales, local connections are scalable. As a result improving efficiency of a small number of...
AdS3/CFT2 In The Presence of N=1 Supergravity
, M.Sc. Thesis Sharif University of Technology ; Rouhani, Shahin (Supervisor)
Abstract
Brown and Henneaux showed that asymptotic symmetries of asymptotically form a conformal group in two dimensions [1]. Also they could derive classical central charge of theory. Fourteen years later, Maldacena, conjectured that this Holographic correspondence could be true for a specific theory a simplified chromodynamics in the boundary of ), this holographic theory attracted physicist communitee's attention. Many physicists tried to make this conjecture more precise. It is worth to say that, no example of holographic correspondence has been completely proven, till now, Because of the difficulty of the calculation. However these days we consider Madacena conjectrure in any arbitrary...
Design and Implementation of a 2x2 LTE Channel Simulator
, M.Sc. Thesis Sharif University of Technology ; Shabany, Mahdi (Supervisor)
Abstract
In this thesis, a hardware is designed and implemented for testing the perfoemance of MIMO communication systems in LTE standard using SCM channel model. This hardware can be used for measuring the BER of 2x2 wireless systems. This hardware is the first channel emulator, with hardware implementation which is using SCM channel model and implementation of a similar one has not been reported.In addition to the implementation of the mentioned channel emulator, a new approach is used for implementing a Gaussian variate generator (GVG) which is implemented on both FPGA and ASIC and shows better characteristics in comparison with the works done in the past. ASIC implementation of this part is done...
Hardware Trojan Detection: A Size-Aware Approach
, M.Sc. Thesis Sharif University of Technology ; Hesabi, Shahin (Supervisor)
Abstract
With constant increase in the rate of VLSI circuits manufactured in sites separate from the designers and computer architects, global concern regarding the possibility of integration of malware by the manufacturing foundries has arisen. Particularly, one main issue that affects reliability of the chips is modifications or additions with malicious intention,known as Hardware Trojans, which are easily applicable during design and manufacturing phase of chips. There has been an increasing fraud in chip-set manufacturing. Hardware Trojans may leak confidential information outside the chip, to the attacker, may alter the function of circuit, or completely fail a system. Hence search for new...
Accelerating Perfect and Imperfect Loops Using Reconfigurable Architectures
, M.Sc. Thesis Sharif University of Technology ; Hesabi, Shahin (Supervisor)
Abstract
With the widespread use of mobile applications, multimedia and telecommunications, speed of execution has become important. The computation-intensive portions of applications, i.e., loops, devote a significant percentage of their implementation time. Thus, in this thesis, a new method is introduced which greatly increases the execution speed of the loops. Loops are often implemented on coarse-grained reconfiguration architecture (CGRAs) for acceleration, which is a promising architecture with high performance and high power efficiency in comparison to FPGA. In this regard, to reduce the execution time of two-level nested loops, if there are several innermost loops, first, we fuse them, then...
A Scan Chain-Based Aging Monitoring Scheme for Detection of Recycled Chips
, M.Sc. Thesis Sharif University of Technology ; Hesabi, Shahin (Supervisor)
Abstract
Today's latest technology integrated circuits are manufactured for a wide range of applications. With the constant increase in the usage rate of integrated circuits, designing a high reliable system is of utmost importance. The avoidance of counterfeit components is a major challenge of hardware security and trust. Counterfeit components cause lower performance and reduced life span. They are of great concern to the manufacturers and consumers of electronic systems, impacting the security and reliability of these systems. If these parts end up in critical applications like medical systems, satellites, aerospace, or power plants, the results could be catastrophic. So far, there are different...
A Scheme for Counterfeit Chip Detection Using Scan Chain
, M.Sc. Thesis Sharif University of Technology ; Hesabi, Shahin (Supervisor)
Abstract
With constant increase in the rate of VLSI circuits manufactured in sites separate from the designers and computer architects, global concern regarding the possibility of integration of malware by the manufacturing foundries has arisen. Particularly, one main issue that affects relability of the chips is modifications or additions with malicious intension, known as Harware Trojans, which are easily applicable during design and manufacturing phase of chip. This study intends to introduce a model based on the scan chain, a method is provided for intellectual property protection. Currently available IP protection solutions are usually limited to protect single FPGA configurations and require...