Sharif Digital Repository

The exponential growth in the semiconductor industry and hence the increase in chip complexity, has led to more power usage and power density in modern processors. On the other hand, most of today's embedded systems are battery-powered, so the power consumption is one of the most critical criteria in these systems. Dynamic Voltage and Frequency Scaling (DVFS) is known as one of the most effective energy-saving methods. In this paper, we propose the optimal DVFS profile to minimize the energy consumption of a battery-based system with uncertain task execution time under deadline constraints using the Calculus of Variations (CoV). The contribution of this work is to analytically calculate the... 

Due to non-linear factors such as the rate capacity and the recovery effect, the shape of the battery discharge curve plays a significant role in the overall lifetime of the batteries. Accordingly, this paper proposes a simple heuristic battery-aware speed scheduling policy for periodic and non-periodic real-time tasks in Dynamic Voltage Scaling (DVS) systems with non-negligible leakage/static power. A set of comprehensive analysis has been conducted to compare the battery efficiency of the proposed policies with an optimal solution, which could be derived via the Calculus of Variations (CoV). These evaluations have taken into account both periodic and non-periodic tasks in DVS-based... 

This paper presents a hardware control-flow checking scheme for RISC processor-based systems. This Scheme combines two error detection mechanisms to provide high coverage. The first mechanism uses parity bits to detect faults occurring in the opcodes and in the target addresses of branch instructions which lead to erroneous branches. The second mechanism uses signature monitoring to detect errors occurring in the sequential instructions. The scheme is implemented using a watchdog processor for an VHDL model of the LEON2 processor. About 31800 simulation faults were injected into the LEON2 processor. The results show that the error detection coverage is about 99.5% with average detection... 

The theory of silicon optical modulators of ring resonators based on PN diode in reverse bias is primarily discussed. It secondarily provides a full-featured simulator to investigate the behavior of such modulators. Wave equation for ring structure will be solved by using the conformal transformation method and the matrix method as it was used to analyze bent planar optical waveguides. Power coupling between ring and straight waveguides will be calculated by coupled theory of nonparallel waveguides based on experimental results. The time response demonstrates the capability of this device to operate correctly at up to 10 Gbs-1 bitrate, and the frequency spectrum analysis of device shows a >... 

A new Voronoi diagram in Laguerre geometry based on closed-pack non-overlapping circles was proposed. This diagram was used to simulate microstructure of severely deformed materials at different applied strains. Grains size and their fractions were introduced by controlling the size and distribution of nuclei. Edge number distribution and neighboring cells edge number along with area distribution of the simulated Voronoi cells were determined. The edge number distribution was observed to fit gamma distribution more accurately. However, due to high inhomogeneity in the microstructure of the deformed samples at low strains, edge number distribution could not be matched by any distribution... 

Field analysis of ring resonator modulators based on p-i-n diodes has been dissected in this paper. This analysis is performed in time and frequency domains. The conformal transformation method has been used for solving 3-D wave equation. Coupling coefficient between the ring and straight waveguides are obtained by developing the coupled-mode assumption. In the resonant wavelength of 1573.91 nm, a drop of more than 15 dB in frequency spectrum of the device has been observed. Time domain simulation shows that this modulator could support up to 0.4 Gb/s and up to 1.5 Gb/s for NRZ and RZ signals, respectively. Obtained simulation results in both domains have been properly complied with... 

In this paper we generalize Tannakian formalism to fiber functors over general tensor categories. We will show that (under some technical conditions) if the fiber functor has a section, then the source category is equivalent to the category of comodules over a Hopf algebra in the target category. We will also give a description of this Hopf algebra using the notion of framed objects. © 2017 Akadémiai Kiadó, Budapest, Hungary  

Background: In recent years, Advanced Driving Assistance Systems (ADAS) have been significantly progressed, opening novel horizons in reducing traffic accidents. Driver gender can be an affecting factor in the utilization of these systems. The purpose of this study is to review articles examining the effect of gender on the use of ADAS technologies. Methods: This systematic review was conducted in Scopus, Science Direct and PubMed databases using defined key-words in 2018. The retrieved articles were managed and screened through PRISMA-P protocol using EndNote X7 software. The extracted variables were divided into three categories of reaction, behavior, and outcome and also the relevant... 

In this paper, a chaos-based communication system in the presence of unknown transmission delay is studied. First, under master/slave configurations, two chaotic Chen systems as the slaves are synchronized with a master one via unidirectional coupling. Then at the transmitter, information of an image is embedded within a slave-one signal and the resultant signal along with another one which is used to determine the transmission delay is transmitted to the receiver. At the receiver, using the received signals and the slave-two counterpart signal, the image is recovered. The performance of the proposed method is experimentally illustrated  

This paper deals with a new fractional calculus based method to stabilize fixed points of single-input 3D systems. In the proposed method, the control signal is determined by fractional order integration of a linear combination of the system linearized model states. The tuning rule for this method is based on the stability theorems in the incommensurate fractional order systems. The introduced technique can be used in suppression of chaotic oscillations. To evaluate the performance of the proposed technique in practical applications, it has been experimentally applied to control chaos in two chaotic circuits  

A simple fractional differentiator-based controller is proposed to suppress chaos in a 3D single input chaotic system by stabilizing some of the fixed points. The tuning procedure for the proposed controller is based on the stability concepts in the incommensurate fractional order systems. To show the efficiency of the controller, some numerical simulations are given. Also, to evaluate the practical capability of the proposed controller, we experimentally apply it to control chaos in a chaotic circuit. Moreover, some mathematical analyses are presented to show the applicability of the proposed controller, when its structure is not exactly implementable. © Birkhäuser Boston 2009  

In this study, the effect of different parameters on the fluid transport in a fractured micromodel has been investigated. All experiments in this study have been conducted in a glass micromodel. Since the state of wetting is important in the micromodel, the wetting experiments have been conducted to determine the state of wetting in the micromodel. The used micromodel was wet by water and non-wet regarding normal decane. The fracture network, distribution of pore size, matrix construction, and injection rate are the most important parameters affecting the process. Therefore, the influence of these parameters was studied using five different patterns (A to E). The obtained results from... 

Scaling imbibition curves are of great importance in the characterization and simulation of oil production from naturally fractured reservoirs. Different parameters such as matrix porosity and permeability, oil and water viscosities, matrix dimensions, and oil/water interfacial tensions have an effective on the imbibition process. Studies on the scaling imbibition curves along with the consideration of different assumptions have resulted in various scaling equations. In this work, using an artificial neural network (ANN) method, a novel technique is presented for scaling imbibition recovery curves, which can be used for scaling the experimental and field-scale imbibition cases. The... 

One of the pillars of any machine learning model is its concepts. Using software engineering, we can engineer these concepts and then develop and expand them. In this article, we present a SELM framework for Software Engineering of machine Learning Models. We then evaluate this framework through a case study. Using the SELM framework, we can improve a machine learning process efficiency and provide more accuracy in learning with less processing hardware resources and a smaller training dataset. This issue highlights the importance of an interdisciplinary approach to machine learning. Therefore, in this article, we have provided interdisciplinary teams' proposals for machine learning. © 2021... 

Synchronization of two coupled Chen systems through one of their variables is experimentally studied in this paper. We explore the chaotic behavior of the rescaled Chen system by the bifurcation analysis and computing its Lyapunov exponents which these results are also verified by circuitry realization of the system. Also, using 0-1 test, the chaotic manner of the circuit signals is validated. Finally, we synchronize two Chen circuits using unidirectional continues coupling with only one state variable and show despite the presence of the noise and the fact that two implemented circuits are not completely identical; the circuits achieve complete synchronization. © ICROS  

This paper proposes a fractional order controller to stabilize saddle points of index 2 in a chaotic system. The proposed controller has a simple structure and can be tuned to stabilize fixed points when unstructured norm bounded perturbations exist on the model of the chaotic system. Numerical simulations confirm the ability of the controller to stabilize the fixed points in uncertain chaotic systems. Also, to illustrate the practical capability of the proposed controller, it is experimentally applied to control chaos in a chaotic circuit. © IMechE 2008  

Needs analysis is the key step to designing relevant and useful courses in English for Specific Purposes (ESP), but finding ways to deliver needs in a motivating and interesting way is also paramount. Therefore, investigating students’ motivation to learn ESP is central in needs analysis. Few studies have investigated needs from the perspective of ESP learners’ motivation. Focussing on engineering fields at three Iranian state universities, this study aimed to identify factors that affect engineering students’ motivation for learning technical English in ESP courses. Using a mixed method design, this study was conducted in two phases. In the first phase, semi-structured interviews with 40...