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Photoelectrochemical activity of graphene quantum dots/hierarchical porous TiO2 photoanode
, Article Journal of Alloys and Compounds ; Volume 721 , 2017 , Pages 36-44 ; 09258388 (ISSN) ; Safa, S ; Ebrahimi, M ; Yousefzadeh, S ; Moshfegh, A. Z ; Sharif University of Technology
Elsevier Ltd
2017
Abstract
In this study, initially graphene quantum dots (GQDs) were synthesized by an electrochemical technique and hierarchical porous TiO2 were made by a sol – gel method. Subsequently, GQDs/hierarchical porous TiO2 nanocomposites were prepared by two different methods for the purpose of comparison: spin coating (SC) and electrophoretic (EP) deposition. The GQDs/hierarchical porous TiO2 nanocomposites were characterized by various analytical methods including field emission scanning electron microscopy, atomic force microscopy, transmission electron microscopy, high resolution transmission electron microscopy, Fourier transform infra-red spectroscopy, photoluminescence spectroscopy and...
An audio band low voltage CT-ΔΣ modulator with VCO-based quantizer
, Article 18th IEEE International Conference on Electronics, Circuits, and Systems, ICECS 2011, 11 December 2011 through 14 December 2011 ; December , 2011 , Pages 232-235 ; 9781457718458 (ISBN) ; Sharifkhani, M ; Sharif University of Technology
2011
Abstract
This paper presents the design and implementation of a low power, low voltage, continuous time delta sigma modulator for audio band in 90 nm CMOS technology. A VCO-based integrator and quantizer are used. Inherent dynamic element matching (DEM) of the quantizer eliminates the need for explicit DEM logic which results in a short excess-delay and power saving. Simulation results show that the modulator achieves 78 dB SNDR and 87 dB SNR in a 20 kHz input bandwidth and dissipates 106 μW from 1 V supply. The power consumption for different parts is discussed
Lower extremity kinematic analysis in male athletes with unilateral anterior cruciate reconstruction in a jump-landing task and its association with return to sport criteria
, Article BMC Musculoskeletal Disorders ; Volume 20, Issue 1 , 2019 ; 14712474 (ISSN) ; Esfandiarpour, F ; Mehdizadeh, S ; Yousefzadeh, N. K ; Parnianpour, M ; Sharif University of Technology
BioMed Central Ltd
2019
Abstract
Background: Return to sport (RTS) criteria are widely being used to identify anterior cruciate ligament reconstructed (ACLR) athletes ready to return to sportive activity and reduce risk of ACL re-injury. However, studies show a high rate of ACL re-injury in athletes who passed RTS criteria. This indicates that the current RTS criteria might not be sufficient to determine return to sport time in ACLR athletes. Previous studies have reported a close association between altered lower limb kinematics and ACL re-injury. However, it is not clear how lower extremity kinematics differs between ACLR athletes who passed the RTS-criteria and who failed. This study compared lower extremity kinematics...
An Investigation on Physical and Photochemical Properties of Sol-Gel Derived MWCNT-WO3 Nanocomposite thin Films
, M.Sc. Thesis Sharif University of Technology ; Moshfegh, Alireza (Supervisor)
Abstract
WO3 have good electrochromic, gas sensor, photocatalyst, phoelectrochemical (PEC) properties. due its properties, tungsten oxide have many application in technology and industry. In this thesis, pure WO3 thin film and MWCNT-WO3 nanocomposite thin films with different weight percent of MWCNT/WO3 utilize for energy domain, particular hydrogen production with phoelectrochemical reactions spiliting water. For this purpose, initially WO3 thin films were deposited on glass and ITO substrates using sol-gel dip-coating method. Optical and surface properties of the films dried at 100ºC and annealed at 400 ºC had been investigated. UV-Visible spectrophotometer, atomic force microscopy (AFM), X-ray...
Synthesis and Investigation on Physical and Photoelectrochemical Properties of Visible Active TiO2/Graphene Based Nanocomposite Thin Films for Hydrogen Production
, Ph.D. Dissertation Sharif University of Technology ; Moshfegh, Alireza (Supervisor)
Abstract
World population growth, depletion of fossil fuels resources depletion and increased air pollution resulting from their consumption, human society has had to replace fossil fuels with renewable sources. In this context, the production of hydrogen using solar energy is feasible candidate to replace fossil fuels, which can be produced by water splitting in a photoelectrochemical (PEC) cell using an appropriate photocatalyst. This clean production method has been attended by many researchers in recent years. The most common photocatalyst for the conversion of sunlight to hydrogen by splitting water is Titanium dioxide (TiO2). But high energy gap and fast electron-hole recombination rate in TiO2...
A 10MHz CTDSM with differential VCO-based quantizer in 90nm
, Article Proceedings of the 2013 8th International Conference on Design and Technology of Integrated Systems in Nanoscale Era, DTIS 2013 ; 2013 , Pages 128-133 ; 9781467360388 (ISBN) ; Hajian, A ; Sharifkhani, M ; Sharif University of Technology
2013
Abstract
This paper presents a new architecture for VCO-based Continuous Time Delta Sigma Modulators. This approach is based on the differential configuration for the quantizer while maintains its inherent dynamic element matching property. Consuming no additional power and area compared to the conventional scheme, this architecture can eliminate the even orders of harmonic distortion and achieve higher linearity. Theoretical analysis for signal to quantization noise, power and area consumption and mismatch effect is provided. To illustrate the effectiveness of the new architecture in continuous time modulators, a modulator with 640 MHz sampling rate utilizing the mentioned quantizer is simulated in...
Application of particle swarm optimization and genetic algorithm for optimization of a southern Iranian oilfield
, Article Journal of Petroleum Exploration and Production ; Volume 11, Issue 4 , 2021 , Pages 1781-1796 ; 21900558 (ISSN) ; Dehghan, A ; Yousefzadeh, R ; Sharif University of Technology
Springer Science and Business Media B.V
2021
Abstract
Optimization of the placement and operational conditions of oil wells plays an important role in the development of the oilfields. Several automatic optimization algorithms have been used by different authors in recent years. However, different optimizers give different results depending on the nature of the problem. In the current study, a comparison between the genetic algorithm and particle swarm optimization algorithms was made to optimize the operational conditions of the injection and production wells and also to optimize the location of the injection wells in a southern Iranian oilfield. The current study was carried out with the principal purpose of evaluating and comparing the...
Design and Implementation of Low Power Delta Sigma Modulator for Audio Application
, M.Sc. Thesis Sharif University of Technology ; Sharifkhani, Mohammad (Supervisor)
Abstract
iN This thesis, Design and implementation of a low voltage, low power Delta-Sigma Modulator (DSM) is presented. System level considerations have been discussed thoroughly. In addition a systematic design flow in the context of continuous time delta sigma modulators is provided. While voltage-domain signal processing becomes more difficult in deep sub-micron processes, a finer time resolution is achievable. Time-domain quantizers can ameliorate the design challenges of flash quantizers which arises from lower supply voltages and higher fraction of comparator metastable region. VCO based quantizer such as voltage to frequency and voltage to phase considered as time domain quantizers can be a...
Constructing BiVO4/Graphene/TiO2 nanocomposite photoanode for photoelectrochemical conversion applications
, Article Journal of Electroanalytical Chemistry ; Volume 763 , 2016 , Pages 1-9 ; 15726657 (ISSN) ; Faraji, M ; Moshfegh, A. Z ; Sharif University of Technology
Elsevier B.V
2016
Abstract
BiVO4/Graphene/TiO2 as a novel nanocomposite photoanode was designed, synthesized and characterized for photoelectrochemical application. BiVO4/Graphene nanocomposite was initially synthesized by photocatalytic process and then, BiVO4/Graphene/TiO2 nanocomposite thin film was prepared by deposition of the BiVO4/Graphene solution onto the surface of sol-gel derived TiO2 thin film. Morphology, crystal structure, surface chemical composition and optical properties of the synthesized BiVO4/Graphene/TiO2 nanocomposite thin film were characterized and compared with the BiVO4/Graphene and pure TiO2 samples. Observations of scanning electron microscopy (SEM) images revealed that the surface of the...
The Impact of Unconditional Cash Subsidies on the time Allocation of Household by using “Dose-Response Function”
, M.Sc. Thesis Sharif University of Technology ; Keshavarz Haddad, Gholamreza (Supervisor)
Abstract
This study aims to estimate impact of the energy subsidy reform on households’ head time allocation in rural and urban areas in to 2011 to 2013 by making use of treatment effect particularly dose response function approach. Our main contribution is estimation and calculation of labor supply reaction to the unconditional cash transfer by dose of the subsidy that they received, while the previous works in this literature have used the well know binary variable of being in the exposure of program. To control for the demand determinants which are deriving the labor demand, we include the province level GDP and unemployment rate in the model. Our findings show that the subsidy dose does not have...
MWCNT/WO3 nanocomposite photoanode for visible light induced water splitting
, Article Journal of Solid State Chemistry ; Volume 204 , 2013 , Pages 341-347 ; 00224596 (ISSN) ; Reyhani, A ; Naseri, N ; Moshfegh, A. Z ; Sharif University of Technology
2013
Abstract
The Multi-walled carbon nanotube (MWCNT)/WO3 nanocomposite thin films with different MWCNT's weight percentages were prepared by sol-gel method as visible light induced photoanode in water splitting reaction. Weight percentage of MWCNT in the all nanocomposite thin films was confirmed by TGA/DSC analysis. According to XPS analysis, oxygenated groups at the surface of the MWCNT and stoichiometric formation of WO3 thin films were determined, while the crystalline structure of the nanocomposite samples was studied by XRD indicating (0 0 2) peak of MWCNT in the monoclinic phase of WO3. The influence of different weight percentage (wt%) of MWCNT on WO3 photoactivity showed that the electron...
Analysis and Development of Security Enhancements in Layer 2 Ethernet Based Networks
, M.Sc. Thesis Sharif University of Technology ; Pakravan, Mohammad Reza (Supervisor)
Abstract
Ethernet is among the most popular forms of data networking in the world. It has been widely used for local area networks and recently, it has also become very popular in metro area networks. As the usage of Ethernet grows, security and privacy of data transport using Ethernet becomes more important. As a result, there have been a lot of developments in improving security of Ethernet. In this thesis, we first provide a brief introduction of data security concepts. Then we briefly review important encryption standards. We focus on IEEE MACsec standard to provide the required security for Ethernet data transport. We have implemented the core encryption/decryption algorithms using HDL codes. We...
CdS nanoparticle sensitized titanium dioxide decorated graphene for enhancing visible light induced photoanode
, Article Applied Surface Science ; Vol. 320, issue , 30 November , 2014 , pp. 772-779 ; ISSN: 01694332 ; Faraji, M ; Nien, Y. T ; Moshfegh, A. Z ; Sharif University of Technology
2014
Abstract
CdS/TiO2/graphene (CTG) nanocomposite thin films were synthesized by a facile production route. The TiO2/graphene (TG) nanocomposite was initially fabricated by sol-gel method in such a way that TiO2 nanoparticles loaded on graphene oxide (GO) sheet via photocatalytic process. Then, CdS nanoparticles were deposited on the TG thin film by successive ion layer adsorption and reaction process (SILAR) approach. Based on atomic force microscopy (AFM), scanning electron microscopy (SEM) and transmission electron microscopy (TEM) analyses, the TG thin film possessed a larger surface area as compared with the pure TiO2 thin film due to presence of graphene sheet. UV/visible spectroscopy exhibited...
Unifying L1 Data Cache and Shared Memory in GPUs
, M.Sc. Thesis Sharif University of Technology ; Sarbazi Azad, Hamid (Supervisor)
Abstract
Graphics Processing Units (GPUs) employ a scratch-pad memory (a.k.a., shared memory) in each streaming multiprocessor to accelerate data sharing among the threads in a thread block and provide a software-managed cache for the programmers.However, we observe that about 60% of GPU workloads of several well-known benchmark suites do not use shared memory. Morever, among those workloads that use shared memory, about 42% of shared memory is not utilized, on average. On the other hand, we observe that many general purpose GPU applications suffer from the low hit rate and limited bandwidth of L1 data cache.We aim to use shared memory space and its corrsponding bandwidth for improving L1 data cache,...
NURA: A framework for supporting non-uniform resource accesses in GPUs
, Article Performance Evaluation Review ; Volume 50, Issue 1 , 2022 , Pages 39-40 ; 01635999 (ISSN) ; Mahani, N ; Baxishi, H ; Yousefzadeh, E ; Sadrosadati, M ; Sarbazi Azad, H ; Sharif University of Technology
Association for Computing Machinery
2022
Abstract
Multi-application execution in Graphics Processing Units (GPUs), a promising way to utilize GPU resources, is still challenging. Some pieces of prior work (e.g. spatial multitasking) have limited opportunity to improve resource utilization, while others, e.g. simultaneous multi-kernel, provide fine-grained resource sharing at the price of unfair execution. This paper proposes a new multi-application paradigm for GPUs, called NURA, that provides high potential to improve resource utilization and ensure fairness and Quality-of-Service(QoS). The key idea is that each streaming multiprocessor (SM) executes the Cooperative Thread Arrays (CTAs) that belong to only one application (similar to...
Improved solar-driven photocatalytic activity of hybrid graphene quantum dots/ZnO nanowires: a direct Z-scheme mechanism
, Article ACS Sustainable Chemistry and Engineering ; Volume 5, Issue 1 , 2017 , Pages 367-375 ; 21680485 (ISSN) ; Samadi, M ; Yousefzadeh, S ; Soltani, M ; Rahimi, A ; Chou, T. C ; Chen, L. C ; Chen, K. H ; Moshfegh, A. Z ; Sharif University of Technology
2017
Abstract
Herein, an electrochemical technique as a cost-effective and one-step approach was utilized to fabricate graphene quantum dots (GQDs). Different amounts of GQDs (0, 0.2, 0.4, 0.8, and 1.2 wt %) were decorated uniformly on the surface of anodized ZnO nanowires (NWs) forming GQD/ZnO NWs. Transmission electron microscopy and atomic force microscopy confirmed formation of GQDs on the ZnO NWs, 12-22 nm in width and 1-3 graphene layers thick. X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy were employed to verify the functional groups on the surface of GQDs, and the results indicated that GQDs readily anchored on the surface of ZnO NWs. The GQD/ZnO NWs exhibited a...
NURA: A framework for supporting non-uniform resource accesses in GPUs
, Article 2022 ACM SIGMETRICS/IFIP PERFORMANCE Joint International Conference on Measurement and Modeling of Computer Systems, SIGMETRICS/PERFORMANCE 2022, 6 June 2022 through 10 June 2022 ; 2022 , Pages 39-40 ; 9781450391412 (ISBN) ; Mahani, N ; Baxishi, H ; Yousefzadeh, E ; Sadrosadati, M ; Sarbazi Azad, H ; ACM SIGMETRICS ; Sharif University of Technology
Association for Computing Machinery, Inc
2022
Abstract
Multi-application execution in Graphics Processing Units (GPUs), a promising way to utilize GPU resources, is still challenging. Some pieces of prior work (e.g. spatial multitasking) have limited opportunity to improve resource utilization, while others, e.g. simultaneous multi-kernel, provide fine-grained resource sharing at the price of unfair execution. This paper proposes a new multi-application paradigm for GPUs, called NURA, that provides high potential to improve resource utilization and ensure fairness and Quality-of-Service(QoS). The key idea is that each streaming multiprocessor (SM) executes the Cooperative Thread Arrays (CTAs) that belong to only one application (similar to...
NURA: A framework for supporting non-uniform resource accesses in gpus
, Article Proceedings of the ACM on Measurement and Analysis of Computing Systems ; Volume 6, Issue 1 , 2022 ; 24761249 (ISSN) ; Mahani, N ; Baxishi, H ; Yousefzadeh Asl Miandoab, E ; Sadrosadati, M ; Sarbazi Azad, H ; Sharif University of Technology
Association for Computing Machinery
2022
Abstract
Multi-application execution in Graphics Processing Units (GPUs), a promising way to utilize GPU resources, is still challenging. Some pieces of prior work (e.g., spatial multitasking) have limited opportunity to improve resource utilization, while other works, e.g., simultaneous multi-kernel, provide fine-grained resource sharing at the price of unfair execution. This paper proposes a new multi-application paradigm for GPUs, called NURA, that provides high potential to improve resource utilization and ensures fairness and Quality-of-Service (QoS). The key idea is that each streaming multiprocessor (SM) executes Cooperative Thread Arrays (CTAs) belong to only one application (similar to the...
The relationship between an EFL teacher's gender and students' willingness to communicate
, Article International Journal of Communication and Linguistic Studies ; Volume 10, Issue 4 , 2013 , Pages 17-29 ; 23277882 (ISSN) ; Pakzadian, S. S
Common Ground Publishing
2013
Abstract
Learning a foreign language encompasses a process of trial and error that can lead to the progression of the learner's interlanguage, meaning that the learners make use of their language knowledge that receives feedback and brings about progress through diagnosis of the problems and being corrected by the teacher. Therefore, there exists a need to analyze the underlying reasons causing the students to remain taciturn with a low willingness to communicate (WTC) during a language class. There has been much work done investigating the role of the learner's stable personal characteristics (traits) along with their situational changes at a specific time (states) that influence the student's...
An automated simple algorithm for realistic pore network extraction from micro-tomography images
, Article Journal of Petroleum Science and Engineering ; Vol. 123, issue , 2014 , pp. 164-171 ; ISSN: 09204105 ; Jamshidi, S ; Salehi, S
2014
Abstract
Using 3-D scanned data to analyze and extract pore network plays a vital role in investigation of porous media's characteristics. In this paper, a new simple method is developed to detect pores and throats for analyzing the connectivity and permeability of the network. This automated method utilizes some of the common and well-known image processing functions which are widely accessible by researchers and this has led to an easy algorithm implementation. In this method, after polishing and quality control of images, using city-block distance function and watershed segmentation algorithm, pores and throats are detected and 3-D network is produced. This method can also be applied on 2-D images...