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Numerical Study and Sensitivity Analysis of a Flowmeter Based on a Fluidic Oscillator
, M.Sc. Thesis Sharif University of Technology ; Ebrahimi, Abbas (Supervisor) ; Ghamkhar, Kamran (Co-Supervisor)
Abstract
In this thesis, the flow behavior in a fluidic oscillator-based flowmeter is investigated using two-dimensional numerical simulations and experimental tests. The primary objective of this study is to analyze the effect of geometrical parameters and flow conditions on the performance of the fluidic oscillator and to determine the relationships between key parameters such as oscillation frequency, oscillation amplitude, pressure drop, and the standard deviation of the Strouhal number. The numerical simulations are conducted using the Unsteady Reynolds-Averaged Navier-Stokes (URANS) model and the finite volume method, with the k−ω SST turbulence model applied for flow modeling. The computations...
Experimental study of stall control over an airfoil with dual excitation of separated shear layers
, Article Aerospace Science and Technology ; Volume 82-83 , 2018 , Pages 402-411 ; 12709638 (ISSN) ; Hajipour, M ; Ghamkhar, K ; Sharif University of Technology
2018
Abstract
This paper investigates the stall control over an airfoil employing dual excitation of separated shear layers with dielectric barrier discharge plasma actuators. This novel approach is studied experimentally on the NACA 0015 airfoil at the angle of attack and Reynolds number of 14° and 0.3×106, respectively. To analyze the baseline flow, Time-averaged pressure distributions on the airfoil surfaces are evaluated with 40 pressure taps. Further, the dominant natural frequencies associated with flow structures in the airfoil wake are examined utilizing a hot-wire anemometer. Two plasma actuators, one on the suction side just upstream the separation point and the other on the pressure side at the...
Wavelet analysis of the flow field around an oscillating airfoil undergoing pure pitching motion at low Reynolds number
, Article Physics of Fluids ; Volume 35, Issue 6 , 2023 ; 10706631 (ISSN) ; Ebrahimi, A ; Shariloo, K ; Sharif University of Technology
American Institute of Physics Inc
2023
Abstract
This paper investigates the flow field around a NACA (National Advisory Committee for Aeronautics) 0012 airfoil undergoing pure pitching motion using continuous wavelet transform. Wind tunnel experiments were performed with a test-stand that provides a wide range of oscillation frequencies (f = 0-10 Hz). Sinusoidal pure pitching motion was considered with respect to the quarter chord for five reduced frequencies (K = 0.05, 0.1, 0.15, 0.2, and 0.3) at a Reynolds number of Re = 6 × 104. Mean angle of attack and pitch amplitude for all the cases were considered 0° and 6°, respectively. Unsteady surface pressure measurement was conducted, and the lift coefficient was calculated based on the...
Aerodynamic Performance Investigation of a Tandem Airfoil Configuration at Low Reynolds Numbers
, Ph.D. Dissertation Sharif University of Technology ; Ebrahimi, Abbas (Supervisor)
Abstract
The main goal of this research is to study the flow field around an airfoil undergoing pure pitching motion in single and tandem configurations. Despite numerous experimental and numerical studies on flow structures at low Reynolds numbers, less attention has been given to the frequency analysis of flow structures in pitching airfoils. Additionally, the effect of reduced frequency on lift coefficient behavior, surface pressure, and wake pressure for a pitching airfoil at low Reynolds numbers is not well understood. Specifically, the unsteady aerodynamics of tandem pitching foils with independent reduced frequencies has been remained less assessed. In this dissertation the physics of the flow...
Effect of Corona Virus Outbreak on Different Industries in Iran stock Exchange
, M.Sc. Thesis Sharif University of Technology ; Zamani, Shiva (Supervisor) ; Talebiyan, Masoud (Supervisor)
Abstract
This research is an event study about the effects of the Corona Virus Outbreak on different industries in the Iran Stock Exchange. This study examines which industries had been affected more negatively or positively by the COVID-19 pandemic outbreak. In the first step, we calculate Alphas, Betas, and expected returns of stocks in an estimation window before the event using the market model. Then, we group all stocks in 17 different industries and calculate average cumulative abnormal returns in the event period as good measures for examining defects of this outbreak. Our results show that transportation, chemical products, processed products, real estate, and automobile manufacturing were...
Experimental Study of a DBD Plasma Actuators Location and Actuation Frequency on Flow Separation Control
,
M.Sc. Thesis
Sharif University of Technology
;
Ebrahimi, Abbas
(Supervisor)
;
Puoryousefi, Gholamhossein
(Co-Supervisor)
Abstract
This thesis investigates the stall control over an airfoil employing dual excitation of separated shear layers with DBD plasma actuators. This research is studied experimentally on the NACA 0015 airfoil at the angle of attack and Reynolds number of 14° and 300000, respectively. Two plasma actuators, one on the suction side just upstream the separation point and the other on the pressure side at the trailing edge, are exploited to control the baseline flow. Surface pressure distribution, as well as the dominant natural frequency associated with flow structures in the wake, are evaluated. Based on the active actuators, three controlled cases are considered in the present study. In the first...
Dark silicon and the history of computing
, Article Advances in Computers ; Volume 110 , 2018 , Pages 1-33 ; 00652458 (ISSN); 9780128153581 (ISBN) ; Sarbazi Azad, H ; Sharif University of Technology
Academic Press Inc
2018
Abstract
For many years, computer designers benefitted from Moore's law and Dennard scaling to significantly improve the speed of single-core processors. The failure of Dennard scaling pushed the computer industry toward homogenous multicore processors for the performance improvement to continue without significant increase in power consumption. Unfortunately, even homogeneous multicore processors cannot offer the level of energy efficiency required to operate all the cores at the same time in today's and especially tomorrow's technologies. As a result of lack of energy efficiency, not all the cores in a multicore processor can be functional at the same time. This phenomenon is referred to as dark...
Temporal prefetching
, Article Advances in Computers ; 2021 ; 00652458 (ISSN) ; Sarbazi Azad, H ; Sharif University of Technology
Academic Press Inc
2021
Abstract
Many applications, including big-data server applications, frequently encounter data misses. Consequently, they lose significant performance potential. Fortunately, data accesses of many of these applications follow temporal correlations, which means data accesses repeat over time. Temporal correlations occur because applications usually consist of loops, and hence, the sequence of instructions that constitute the body of a loop repeats many times, leading to data access repetition. Temporal data prefetchers take advantage of temporal correlation to predict and prefetch future memory accesses. In this chapter, we introduce the concept of temporal prefetching and present two instances of...
Spatial prefetching
, Article Advances in Computers ; 2021 ; 00652458 (ISSN) ; Sarbazi Azad, H ; Sharif University of Technology
Academic Press Inc
2021
Abstract
Many applications extensively use data objects with a regular and fixed layout, which leads to the recurrence of access patterns over memory regions. Spatial data prefetching techniques exploit this phenomenon to prefetch future memory references and hide their long latency. Spatial prefetchers are particularly of interest because they usually only need a small storage budget. In this chapter, we introduce the concept of spatial prefetching and present two instances of spatial data prefetchers, SMS and VLDP. © 2021 Elsevier Inc
Preface
, Article Advances in Computers ; Volume 125 , 2022 , Pages ix-x ; 00652458 (ISSN); 9780323851190 (ISBN) ; Sarbazi Azad, H ; Sharif University of Technology
Academic Press Inc
2022
Temporal prefetching
, Article Advances in Computers ; Volume 125 , 2022 , Pages 31-41 ; 00652458 (ISSN); 9780323851190 (ISBN) ; Sarbazi Azad, H ; Sharif University of Technology
Academic Press Inc
2022
Abstract
Many applications, including big-data server applications, frequently encounter data misses. Consequently, they lose significant performance potential. Fortunately, data accesses of many of these applications follow temporal correlations, which means data accesses repeat over time. Temporal correlations occur because applications usually consist of loops, and hence, the sequence of instructions that constitute the body of a loop repeats many times, leading to data access repetition. Temporal data prefetchers take advantage of temporal correlation to predict and prefetch future memory accesses. In this chapter, we introduce the concept of temporal prefetching and present two instances of...
Spatial prefetching
, Article Advances in Computers ; Volume 125 , 2022 , Pages 19-29 ; 00652458 (ISSN); 9780323851190 (ISBN) ; Sarbazi Azad, H ; Sharif University of Technology
Academic Press Inc
2022
Abstract
Many applications extensively use data objects with a regular and fixed layout, which leads to the recurrence of access patterns over memory regions. Spatial data prefetching techniques exploit this phenomenon to prefetch future memory references and hide their long latency. Spatial prefetchers are particularly of interest because they usually only need a small storage budget. In this chapter, we introduce the concept of spatial prefetching and present two instances of spatial data prefetchers, SMS and VLDP. © 2022 Elsevier Inc
Synthesis, and Characterization of Binuclear Platinum (IV)with Coinage Metals
, M.Sc. Thesis Sharif University of Technology ; Jamali, Sirous (Supervisor)
Abstract
In this research binuclear platinum(IV) complexes with coinage metals have been synthesized and characterized. the trimethyl platinum(IV) complex [PtMe3(phthalazine)3]+X- has been prepared by the reaction of [PtMe3(THF)]4 with 3 equiv. phthalazine and used as initial material. The first complex, [PtMe3(µ-(phthalazine)2Cl)PtMe3], synthesized via reaction of 2 equiv. [Pt(Me)3(Phthalazine)3] with 1 equiv. [AuClSMe2]. The second complex, [PtMe3(µ-phthalazine)3Ag][BF4], synthesized by reaction of one equiv. of each compound [Ag(CH3CN)4]BF4 and [Pt(Me)3(Phthalazine)3] And the third complex, [PtMe3(µ-phthalazine)3Cu][PF6], synthesized like second one via reaction of [Cu(CH3CN)4]PF6 and...
Processing Thin Magnesium Tubes by TCAP Process with Trapezoidal Geometry and Fabrication of Magnesium Microtubes with a Novel Method
, M.Sc. Thesis Sharif University of Technology ; Assempour, Ahmad (Supervisor)
Abstract
Due to compability of Magnesium with the body, it is a suitable material for making biodegradable stents, Althogh, its mechanical properties are not desirable for stent application. Accordingly, lately, magnesium’s microstructure and mechanical properties have been improved using various methods, including the process of severe plastic deformation (SPD). Many severe plastic deformation methods have been introduced for the fabrication of ultrafine grain tubes till now, which the process of tubular channel angular pressing (TCAP) is the most effective one. In the first part of the research, Magnesium tubes with a thickness of 1 mm were processed using the TCAP with a trapezoidal channel, and...
Online visual gyroscope for autonomous cars
, Article 24th Iranian Conference on Electrical Engineering, ICEE 2016, 10 May 2016 through 12 May 2016 ; 2016 , Pages 113-118 ; 9781467387897 (ISBN) ; Karimian, M ; Nazemipour, A ; Manzuri, M.T ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2016
Abstract
Knowing the exact position and rotation is a crucial necessity for the navigation of autonomous robots. Even in outdoor environments GPS signals are not always accessible for estimating online rotation and position of robots. Also inertial aided navigation methods have their own defects such as the drift of gyroscope or inaccuracy of accelerometer in agile motions and environmental sensitivity of compass. In this article, we have introduced a novel online visual gyroscope that can estimate the rotation of a moving car with analyzing the images of a monocular camera installed on it. Our real time visual gyroscope utilizes an efficient method of rotation estimation between each pair of camera...
HDL based simulation framework for a DPA secured embedded system
, Article CSI Symposium on Real-Time and Embedded Systems and Technologies, RTEST 2015, 7 October 2015 through 8 October 2015 ; October , 2015 , Page(s): 1 - 6 ; 9781467380478 (ISBN) ; Marjovi, A ; Fanian, A ; Safayani, M ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2015
Abstract
Side Channel Analysis (SCA) are still harmful threats against security of embedded systems. Due to the fact that every kind of SCA attack or countermeasure against it needs to be implemented before evaluation, a huge amount of time and cost of this process is paid for providing high resolution measurement tools, calibrating them and also implementation of proposed design on ASIC or target platform. In this paper, we have introduced a novel simulation platform for evaluation of power based SCA attacks and countermeasures. We have used Synopsys power analysis tools in order to simulate a processor and implement a successful Differential Power Analysis (DPA) attack on it. Then we focused on the...
An efficient hybrid-switched network-on-chip for chip multiprocessors
, Article IEEE Transactions on Computers ; Volume 65, Issue 5 , 2016 , Pages 1656-1662 ; 00189340 (ISSN) ; Modarressi, M ; Sarbazi Azad, H ; Sharif University of Technology
IEEE Computer Society
2016
Abstract
Chip multiprocessors (CMPs) require a low-latency interconnect fabric network-on-chip (NoC) to minimize processor stall time on instruction and data accesses that are serviced by the last-level cache (LLC). While packet-switched mesh interconnects sacrifice performance of many-core processors due to NoC-induced delays, existing circuit-switched interconnects do not offer lower network delays as they cannot hide the time it takes to set up a circuit. To address this problem, this work introduces CIMA - a hybrid circuit-switched and packet-switched mesh-based interconnection network that affords low LLC access delays at a small area cost. CIMA uses virtual cut-through (VCT) switching for short...
Near-Ideal networks-on-chip for servers
, Article 23rd IEEE Symposium on High Performance Computer Architecture, HPCA 2017, 4 February 2017 through 8 February 2017 ; 2017 , Pages 277-288 ; 15300897 (ISSN); 9781509049851 (ISBN) ; Modarressi, M ; Sarbazi Azad, H ; Sharif University of Technology
IEEE Computer Society
2017
Abstract
Server workloads benefit from execution on many-core processors due to their massive request-level parallelism. A key characteristic of server workloads is the large instruction footprints. While a shared last-level cache (LLC) captures the footprints, it necessitates a low-latency network-on-chip (NOC) to minimize the core stall time on accesses serviced by the LLC. As strict quality-of-service requirements preclude the use of lean cores in server processors, we observe that even state-of-the-art single-cycle multi-hop NOCs are far from ideal because they impose significant NOC-induced delays on the LLC access latency, and diminish performance. Most of the NOC delay is due to per-hop...
Code layout optimization for Near-Ideal instruction cache
, Article IEEE Computer Architecture Letters ; Volume 18, Issue 2 , 2019 , Pages 124-127 ; 15566056 (ISSN) ; Lotfi Kamran, P ; Sarbazi Azad, H ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2019
Abstract
Instruction cache misses are a significant source of performance degradation in server workloads because of their large instruction footprints and complex control flow. Due to the importance of reducing the number of instruction cache misses, there has been a myriad of proposals for hardware instruction prefetchers in the past two decades. While effectual, state-of-the-art hardware instruction prefetchers either impose considerable storage overhead or require significant changes in the frontend of a processor. Unlike hardware instruction prefetchers, code-layout optimization techniques profile a program and then reorder the code layout of the program to increase spatial locality, and hence,...
Divide and conquer frontend bottleneck
, Article 47th ACM/IEEE Annual International Symposium on Computer Architecture, ISCA 2020, 30 May 2020 through 3 June 2020 ; Volume 2020-May , 2020 , Pages 65-78 ; Lotfi Kamran, P ; Sarbazi Azad, H ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2020
Abstract
The frontend stalls caused by instruction and BTB misses are a significant source of performance degradation in server processors. Prefetchers are commonly employed to mitigate frontend bottleneck. However, next-line prefetchers, which are available in server processors, are incapable of eliminating a considerable number of L1 instruction misses. Temporal instruction prefetchers, on the other hand, effectively remove most of the instruction and BTB misses but impose significant area overhead. Recently, an old idea of using BTB-directed instruction prefetching is revived to address the limitations of temporal instruction prefetchers. While this approach leads to prefetchers with low area...