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Performance evaluation of a modular design ofwind tower withwetted surfaces
, Article Energies ; Volume 10, Issue 7 , 2017 ; 19961073 (ISSN) ; Bahadori, M. N ; Dehghani Sanij, A ; Nourbakhsh, A ; Sharif University of Technology
MDPI AG
2017
Abstract
Wind towers or wind catchers, as passive cooling systems, can provide natural ventilation in buildings located in hot, arid regions. These natural cooling systems can provide thermal comfort for the building inhabitants throughout the warm months. In this paper, a modular design of a wind tower is introduced. The design, called a modular wind tower with wetted surfaces, was investigated experimentally and analytically. To determine the performance of the wind tower, air temperature, relative humidity (RH) and air velocity were measured at different points. Measurements were carried out when the wind speed was zero. The experimental results were compared with the analytical ones. The results...
Optimization of the magnetic properties and microstructure of Co 2+-La3+ substituted strontium hexaferrite by varying the production parameters
, Article Ceramics International ; Vol. 40, issue. 4 , May , 2014 , pp. 5675-5680 ; ISSN: 02728842 ; Vahedi, A ; Nemati, A ; Noorbakhsh, M ; Mirsatari. S. N ; Shaygan, M ; Mackenzie, K. J. D ; Sharif University of Technology
2014
Abstract
The aim of this paper was to improve the magnetic properties of magnetoplumbite-type (M-type) strontium hexaferrite substituted with Co 2+-La3+ produced by conventional ceramic forming techniques. The effect on the magnetic properties of varying the composition of the target compound Sr1-xLaxFe12-yCo yO19 and the primary and secondary firing temperatures was investigated. Microstructure studies and XRD phase analysis indicated that optimum values of the remanent magnetization Br and coercive field Hcj were obtained with a primary firing temperature of 1240 C and a final firing temperature of 1180 C, where (x=y)th 1=0.15, (y/x)exp 2=0.75 and the molar ratio of ferric oxide to strontium...
Laser textured novel patterns on Ti6Al4V alloy for dental implants surface improvement
, Article Journal of Laser Applications ; Volume 33, Issue 4 , 2021 ; 1042346X (ISSN) ; Sadrnezhaad, S. K ; Shoja Razavi, R ; Nourbakhsh, A. A ; Hassanzadeh Nemati, N ; Sharif University of Technology
Laser Institute of America
2021
Abstract
Creating laser texture on dental implants is a novel method for accelerating osseointegration and prolongation of lifespan. The purpose of this research was twofold: (1) Creating intersecting lines pattern with different angles (0°, 15°, 30°, 45°, 60°, 75°, and 90°) on the surface of Ti6Al4V, using pulse Nd:YAG laser with a wavelength of 1064 nm and a pulse length of 170 ns and (2) comparing optical and SEM images, EDS analyses, contact angles (CAs), and surface free energies (FEs) for different intersecting lines angles. CA and FE depended on the intersecting lines angle according to Y = Y 0 + A sin (x B + C), where Y is the CA or FE; x is the intersecting lines angle; and Y0, A, B, and C...
High efficiency and stable perovskite solar cell using zno/rgo qds as an electron transfer layer
, Article Advanced Materials Interfaces ; Volume 3, Issue 11 , 2016 ; 21967350 (ISSN) ; Tavakoli, R ; Nourbakhsh, Z ; Waleed, A ; Virk, U. S ; Fan, Z ; Sharif University of Technology
Wiley-VCH Verlag
2016
Abstract
Fabrication of organohalide perovskite materials on the top of ZnO nanoparticles (NPs) has some beneficial advantages such as room temperature processing; however, the perovskite is not stable on ZnO NPs layer during the annealing process. In fact, there are only a few reports about the fabrication of perovskite solar cells on ZnO NPs layer. Herein, the decomposition mechanism of CH3NH3PbI3 perovskite materials on ZnO is reported, and it is found that the perovskite film on the top of the ZnO layer is converted into PbI2 during the annealing process due to the existence of hydroxide groups on the surface of the ZnO NPs. Depending on the annealing temperature, the reaction rate and the...
Pronoun Resolution with Data Driven Approaches
, M.Sc. Thesis Sharif University of Technology ; Bahrani, Mohammad (Supervisor)
Abstract
Pronoun resolution is one of the challenges of natural language processing. The proposed solutions range from heuristic rule-based to machine learning data driven approaches. In this thesis, we followed a previous machine learning base work to Persian pronoun anaphora resolution. The primary goal of this thesis was to improve results, mainly by extracting more balanced data and to add more features to the extracted feature vectors used in classification. Using PCAC2008 dataset, we considered noun phrase structure as a way to extract more suitable training data. Features added to the extracted data include syntactic and semantic features. Then, we trained and tested different machine learning...
Persian pronoun resolution using data driven approaches
, Article 23rd International Conference on Information and Software Technologies, ICIST 2017, 12 October 2017 through 14 October 2017 ; Volume 756 , 2017 , Pages 574-585 ; 18650929 (ISSN); 9783319676418 (ISBN) ; Bahrani, M ; Sharif University of Technology
Springer Verlag
2017
Abstract
Pronoun resolution is one of the challenges of natural language processing (NLP). The proposed solutions range from heuristic rule-based to machine learning data driven approaches. In this article, we follow a previous machine learning approach on Persian pronoun anaphora resolution. The primary goal of this paper is to improve the results, mainly by extracting more balanced data through using heuristic rules in instance sampling, and utilizing more relevant features in classification. Using PCAC2008 dataset, we consider noun phrase structure as a way to extract more suitable training data. Incorporated features include syntactic and semantic information. Finally, we train and test different...
Photocatalytic properties of mesoporous TiO2 nanocomposites modified with carbon nanotubes and copper
, Article Ceramics International ; 2016 ; 02728842 (ISSN) ; Abbaspour, S ; Masood, M ; Mirsattari, S. N ; Vahedi, A ; Mackenzie, K. J. D ; Sharif University of Technology
Elsevier Ltd
2016
Abstract
The photocatalytic activity of mesoporous TiO2 modified by the addition of carbon nanotubes (CNTs) and Cu is reported. Nanocomposites of carbon nanotubes (CNTs) containing varying amounts of Cu were formed by treatment with Cu2+ then reduced to Cu0 using NaBH4 as the reducing agent. The mesoporous TiO2, synthesized by a sol-gel method from titanium isopropoxide, was combined with the CNT/Cu nanocomposites to form the photocatalysts which were characterized by XRD, SEM, TEM, FTIR, XPS and BET surface area analysis. The photocatalytic properties of the mesoporous TiO2 composites were studied by measuring the degradation of methyl orange (MO) which was optimal in the sample containing 20wt% of...
FoM Optimization in Class-C Oscillators
, M.Sc. Thesis Sharif University of Technology ; Safarian, Amin Ghasem (Supervisor)
Abstract
A key point in designing class-C oscillators is maximizing the Figure-of-Merit (FoM). For this purpose, changing the oscillator’s structure or adjusting its bias current may be used. Previous literatures mostly limit their efforts to the first case, leaving the issue of determining the proper bias current almost untouched. In this work, a new approach recruiting DC voltage of the common source node of the switching pair transistors as an indicator has been presented. Using theoretical analysis, it has been shown that maximizing this voltage will optimize the oscillator in term of the FoM. The proposed indicator has the advantages of not introducing any loading effect to the output node, and...
WordPars: A tool for orthographic and phonological neighborhood and other psycholinguistic statistics in Persian
, Article Behavior Research Methods ; 2021 ; 1554351X (ISSN) ; Saneei, S ; Nourbakhsh, M ; Sharif University of Technology
Springer
2021
Abstract
This paper presents a Windows program providing statistics on word and non-word stimuli in Persian, including word frequency, orthographic and phonological length, orthographic and phonological neighbors, and transposed-letter neighbors. It also generates possible non-words that are orthographic neighbors of the target word. Persian is an under-represented Indo-European language that has historically been influenced by Arabic and adopted certain characteristics in its writing, e.g., the omission of short vowels. This tool aims to help researchers in psycholinguistics, specifically with regard to isolated word recognition in Persian. This downloadable program computes the aforementioned...
WordPars: A tool for orthographic and phonological neighborhood and other psycholinguistic statistics in Persian
, Article Behavior Research Methods ; Volume 54, Issue 4 , 2022 , Pages 1902-1911 ; 1554351X (ISSN) ; Saneei, S ; Nourbakhsh, M ; Sharif University of Technology
Springer
2022
Abstract
This paper presents a Windows program providing statistics on word and non-word stimuli in Persian, including word frequency, orthographic and phonological length, orthographic and phonological neighbors, and transposed-letter neighbors. It also generates possible non-words that are orthographic neighbors of the target word. Persian is an under-represented Indo-European language that has historically been influenced by Arabic and adopted certain characteristics in its writing, e.g., the omission of short vowels. This tool aims to help researchers in psycholinguistics, specifically with regard to isolated word recognition in Persian. This downloadable program computes the aforementioned...
A novel metabolic disorder in the degradation pathway of endogenous methanol due to a mutation in the gene of alcohol dehydrogenase
, Article Clinical Biochemistry ; Volume 90 , 2021 , Pages 66-72 ; 00099120 (ISSN) ; Nourbakhsh, M ; Vafadar, M ; Nourbakhsh, M ; Talebi, S ; Sharifi Zarchi, A ; Salehi Siavashani, E ; Garshasbi, M ; Sharif University of Technology
Elsevier Inc
2021
Abstract
Background: A small amount of methanol is produced endogenously in the human body but it is efficiently metabolized by alcohol dehydrogenase (ADH) and other enzymes, and the products eliminated without harm. In this study, we present a new entity of inborn error of methanol metabolism due to a mutation in the ADH1C gene coding for the γ subunit that is part of several ADH isoenzymes. Results: This disorder was discovered in an 11.58-year-old boy. During one 9-month hospital admission, he had periods of 1–4 days during which he was comatose, and between these periods he was sometimes verbose and euphoric, and had ataxia, dysarthria. Following hemodialysis treatments, he became conscious and...
Chaos Quantities and Computational Challenges
, M.Sc. Thesis Sharif University of Technology ; Razvan, Mohammad Reza (Supervisor)
Abstract
Chaos in dynamical systems refers to the presence of extreme sensitivity to initial conditions in the system’s behavior, which renders the long-term prediction of the sys- tem’s behavior either impossible or highly challenging. This chaotic behavior is also present in deterministic systems. The observation of this concept, besides philosophical changes it has brought about, has been scrutinized in various domains and has provided an explanation for many observed physical, chemical, and biological phenomena. This phenomenon has been studied in diverse sectors such as fluid dynamics, neuronal dy- namics, and chemical reactions. In this research, we intend to analyze chaotic dynamical systems...
Properties Evaluation of Self-Consolidating Concrete Containing Rice Husk Ash
, M.Sc. Thesis Sharif University of Technology ; Jahanshahi, Mohsen (Supervisor) ; Shams, Mohammad Reza (Co-Advisor)
Abstract
The Self-Consolidating (Compacting) Concrete (SCC) is a high performance concrete. Due to preventing it from segregation, SCC is known by its need to higher dosage of super plasticizer and viscose modifying agents. This increases the cost and reduces the popularity of SCC in construction industry. In this thesis, the production of Rice Husk Ash (RHA) from a controlled burning process using a special designed furnace, and cement replacement feasibility in the concrete mixture by low cost RHA, as an active pozzulanic additive have been investigated. Finding an appropriate ratio of replacement with cement for RHA and further effects on mechanical properties of SCC have been evaluated. The...
Web graph compression by edge elimination
, Article Data Compression Conference, DCC 2006, Snowbird, UT, 28 March 2006 through 30 March 2006 ; 2006 , Pages 459- ; 10680314 (ISSN) ; Khalili, H ; Nourbakhsh, E ; Ghodsi, M ; Brandeis University ; Sharif University of Technology
2006
Intelligent semi-active vibration control of eleven degrees of freedom suspension system using magnetorheological dampers
, Article Journal of Mechanical Science and Technology ; Volume 26, Issue 2 , 2012 , Pages 323-334 ; 1738494X (ISSN) ; Sarrafan, A ; Khayyat, A. A. A ; Zabihollah, A ; Sharif University of Technology
2012
Abstract
A novel intelligent semi-active control system for an eleven degrees of freedom passenger car's suspension system using magnetorheological (MR) damper with neuro-fuzzy (NF) control strategy to enhance desired suspension performance is proposed. In comparison with earlier studies, an improvement in problem modeling is made. The proposed method consists of two parts: a fuzzy control strategy to establish an efficient controller to improve ride comfort and road handling (RCH) and an inverse mapping model to estimate the force needed for a semi-active damper. The fuzzy logic rules are extracted based on Sugeno inference engine. The inverse mapping model is based on an artificial neural network...
Performance and exhaust emission characteristics of a spark ignition engine operated with gasoline and CNG blend
, Article Proceedings of the Spring Technical Conference of the ASME Internal Combustion Engine Division ; 2012 , Pages 179-187 ; 15296598 (ISSN) ; 9780791844663 (ISBN) ; Hamidi, A. A ; Mozafari, A. A ; Sharif University of Technology
2012
Abstract
Using CNG as an additive for gasoline is a proper choice due to higher octane number of CNG enriched gasoline with respect to that of gasoline. As a result, it is possible to use gasoline with lower octane number in the engine. This would also mean the increase of compression ratio in SI engines resulting in higher performance and lower gasoline consumption. Over the years, the use of simulation codes to model the thermodynamic cycle of an internal combustion engine have developed tools for more efficient engine designs and fuel combustion. In this study, a thermodynamic cycle simulation of a conventional four-stroke spark-ignition engine has been developed. The model is used to study the...
A comparative study of the performance of a SI engine fuelled by natural gas as alternative fuel by thermodynamic simulation
, Article 2009 ASME Internal Combustion Engine Division Fall Technical Conference, ICEF 2009, Lucerne, 27 September 2009 through 30 September 2009 ; 2009 , Pages 49-57 ; 9780791843635 (ISBN) ; Hamidi, A. A ; Mozafari, A. A ; Sharif University of Technology
American Society of Mechanical Engineers (ASME)
2009
Abstract
With the declining energy resources and increase of pollutant emissions, a great deal of efforts has been focused on the development of alternatives for fossil fuels. One of the promising alternative fuels to gasoline in the internal combustion engine is natural gas [1-5]. The application of natural gas in current internal combustion engines is realistic due to its many benefits. The higher thermal efficiency due to the higher octane value and lower exhaust emissions including CO2 as a result of the lower carbon to hydrogen ratio of the fuel are the two important feature of using CNG as an alternative fuel. It is well known that computer simulation codes are valuable economically as a cost...
Analytical and experimental analyses of nonlinear vibrations in a rotary inverted pendulum
, Article Nonlinear Dynamics ; Volume 107, Issue 3 , 2022 , Pages 1887-1902 ; 0924090X (ISSN) ; Pasharavesh, A ; Khayyat, A. A. A ; Sharif University of Technology
Springer Science and Business Media B.V
2022
Abstract
Gaining insight into possible vibratory responses of dynamical systems around their stable equilibria is an essential step, which must be taken before their design and application. The results of such a study can significantly help prevent instability in closed-loop stabilized systems by avoiding the excitation of the system in the neighborhood of its resonance. This paper investigates nonlinear oscillations of a rotary inverted pendulum (RIP) with a full-state feedback controller. Lagrange’s equations are employed to derive an accurate 2-DoF mathematical model, whose parameter values are extracted by both the measurement and 3D modeling of the real system components. Although the governing...
A suction-controlled ring device to measure the coefficient of lateral soil pressure in unsaturated soils
, Article Geotechnical Testing Journal ; Volume 44, Issue 1 , 2020 ; Garakani, A. A ; Golshani, A ; Mirzaii, A ; Sharif University of Technology
ASTM International
2020
Abstract
A suction-controlled ring device has been developed to continuously measure the coefficient of lateral soil pressure in deformable unsaturated soil samples from the at-rest to the active condition under application of increasing vertical pressure and controlled matric suction. The device incorporates a thin aluminum specimen ring equipped with horizontal strain gages for recording the lateral soil strains. In addition, a sensor recording water volume changes is utilized to continuously monitor the degree of saturation of the soil sample during tests. The matric suction within the soil texture is controlled using the axis translation technique. In order to verify the performance of the ring...
Gum tragacanth gels as a new supporting matrix for immobilization of whole-cell
, Article Iranian Journal of Chemistry and Chemical Engineering ; Volume 24, Issue 4 , 2005 , Pages 1-7 ; 10219986 (ISSN) ; Vaziri, A ; Seifkordi, A. A ; Kheirolomoom, A ; Sharif University of Technology
2005
Abstract
We introduce a new smooth, non-toxic, biocompatible method for cross-linking of gum tragacanth (GT), a polysaccharide of natural origin, in order to serve as a new supporting matrix for immobilization systems. The modified gum is used as a matrix for the catalysis of the conversion of benzyl penicillin to 6-aminopenicillanic acid (6-APA) by means of Escherichia coli ATCC11105 with penicillin G acylase (PGA) activity. The results show that GT beads can not only serve as a proper matrix for immobilization, but show enhanced hydrolysis rate and stability compared to other immobilization systems used for this reaction. This signifies the potential of GT as a biocompatible matrix for...