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ghorbani-shiraz--h
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TiO2/nanoporous silicon hybrid contact for heterojunction crystalline solar cell
, Article RSC Advances ; Volume 6, Issue 60 , 2016 , Pages 55046-55053 ; 20462069 (ISSN) ; Razi Astaraei, F ; Mohammadpour, R ; Sharif University of Technology
Royal Society of Chemistry
2016
Abstract
The conventional solar cell architectures include a p-n junction of c-Si sandwiched by rear and front contacts. The conventional approach features a complex as well as expensive procedure. Here, we propose a new architecture for p-n heterojunction solar cells prepared by a simple and cost-effective procedure. In this regard, (1) a silicon wafer underwent surface treatment through electrochemical anodization. To prepare a stick junction, (2) photoactive TiO2 nanoparticles were deposited over the porous layer by electrophoretic technique. Finally, (3) indium tin oxide (ITO) was sputtered. During the fabrication steps, we examined various anodization times ranging from 6 to 12 min to study the...
Decorated CNT based on porous silicon for hydrogen gas sensing at room temperature
, Article RSC Advances ; Volume 6, Issue 50 , 2016 , Pages 44410-44414 ; 20462069 (ISSN) ; Razi Astaraei, F ; Fardindoost, S ; Hosseini, Z. S ; Sharif University of Technology
Royal Society of Chemistry
2016
Abstract
A new triple-component sensor for detection of H2 was developed based on porous silicon and CNTs. An increase in deposition of CVD catalysis was shown to promote a high and fast response. Also, it was shown that the composite system exhibited good selectivity
Optimal tracking control of an underactuated container ship based on direct Gauss Pseudospectral Method
, Article Scientia Iranica ; Vol. 21, issue. 6 , 2014 ; Salarieh, H ; Sharif University of Technology
2014
Abstract
In this paper, the problem of optimal tracking control for a container ship is addressed. The multi-input-multi-output nonlinear model of the S175 container ship is well established in the literature and represents a challenging problem for control design, where the design requirement is to follow a commanded maneuver at a desired speed. To satisfy the constraints on the states and the control inputs of the vessel nonlinear dynamics and minimize the heading error, a nonlinear optimal controller is formed. To solve the resulted nonlinear constrained optimal control problem, the Gauss Pseudospectral Method (GPM) is used to transcribe the optimal control problem into a Nonlinear Programming...
Impact of harmonics on power quality and losses in power distribution systems
, Article International Journal of Electrical and Computer Engineering ; Volume 5, Issue 1 , 2015 , Pages 166-174 ; 20888708 (ISSN) ; Mokhtari, H ; Sharif University of Technology
2015
Abstract
This paper investigates the harmonic distortion and losses in power distribution systems due to the dramatic increase of nonlinear loads. This paper tries to determine the amount of the harmonics generated by nonlinear loads in residential, commercial and office loads in distribution feeders and estimates the energy losses due to these harmonics. Norton equivalent modeling technique has been used to model the nonlinear loads. The presented harmonic Norton equivalent models of the end user appliances are accurately obtained based on the experimental data taken from the laboratory measurements. A 20 kV/400V distribution feeder is simulated to analyze the impact of nonlinear loads on feeder...
On eigensharp and almost eigensharp graphs
, Article Linear Algebra and Its Applications ; Volume 429, Issue 11-12 , 2008 , Pages 2746-2753 ; 00243795 (ISSN) ; Maimani, H. R ; Sharif University of Technology
2008
Abstract
The minimum number of complete bipartite subgraphs needed to partition the edges of a graph G is denoted by b (G). A known lower bound on b (G) states that b (G) ≥max {p (G), q (G)}, where p (G) and q (G) are the numbers of positive and negative eigenvalues of the adjacency matrix of G, respectively. When equality is attained, G is said to be eigensharp and when b (G) = max {p (G), q (G)} + 1, G is called an almost eigensharp graph. In this paper, we investigate the eigensharpness of graphs with at most one cycle and products of some families of graphs. Among the other results, we show that Pm ∨ Pn, Cm ∨ Pn for m ≡ 2, 3 (mod 4) and Qn when n is odd are eigensharp. We obtain some results on...
A novel double slip loads friction damper to control the seismic response of structures
, Article Engineering Structures ; Volume 225 , 2020 ; Rofooei, F. R ; Sharif University of Technology
Elsevier Ltd
2020
Abstract
In this study, the performance of a proposed friction damper with two slip loads in controlling the seismic response of steel moment resisting buildings structures under moderate and intense earthquake excitations is investigated. The proposed friction damper initially operates with a smaller slip load and could shift to the higher slip load after a certain amount of slippage when subjected to intense ground motions. In this regard, the hysteresis behavior of the proposed double slip loads (DSL) friction damper is modeled and after necessary verifications is imported to the material library of OpenSees software to be used for parametric study. To evaluate the performance of the proposed DSL...
Direct torque control of induction motor by active learning method
, Article PEDSTC 2010 - 1st Power Electronics and Drive Systems and Technologies Conference, 17 February 2010 through 18 February 2010, Tehran ; 2010 , Pages 267-272 ; 9781424459728 (ISBN) ; Akhbari, M ; Mokhtari, H ; Sharif University of Technology
2010
Abstract
This paper presents a high performance direct torque control (DTC) theme for the induction motor (IM). To solve those problems associated with conventional DTC, such as flux and torque ripple, variable switching frequency, inaccuracy in motor model and other parts of system. The Active Learning Method (ALM) is implemented on the DTC. In the Active Learning Method for information modeling, a method known as Ink Drop Spread (IDS) is used. The simulation results of DTC system based on ALM and the comparison of motor performance under the proposed control system with respect to those obtained under conventional DTC confirms its effectiveness and accuracy
Photo-Fenton like degradation of catechol using persulfate activated by UV and ferrous ions: Influencing operational parameters and feasibility studies
, Article Journal of Molecular Liquids ; Volume 249 , 2018 , Pages 463-469 ; 01677322 (ISSN) ; Takdastan, A ; Borghei, S. M ; Sharif University of Technology
Elsevier B.V
2018
Abstract
In the present study, photo-Fenton degradation of catechol from aqueous solution was carried out using UV light and iron ions (Fe2+) as activators of persulfate (PS). Catechol degradation from solution was studied under different experimental variables such as solution pH (2.0–10.0), iron dosages (0.1–0.5 g/L), persulfate loadings (1.0–5.0 mM), initial catechol concentrations (20–100 mg/L) and scavengers (TBA and IPA). The comparative study of catechol removal showed that among the applied approaches, the order of degradation of catechol is as follows: PS/Fe2 +/UV > PS/Fe2 + > UV/PS > PS > UV. Furthermore, higher catechol degradation was observed with increasing iron dosage and PS...
Analysis of Factors Affecting Cavitation of Ogee Crested Spillway in Concrete Dams
, M.Sc. Thesis Sharif University of Technology ; Khaloo, Alireza (Supervisor)
Abstract
In this study, the factors affecting cavitation in the crest of an ogee spillway were investigated. One of the factors affecting the occurrence of cavitation on the ogee crest is the ratio of the head to the design head. As the head ratio increases, the probability of cavitation on the crest increases. The value of the head is also an effective parameter for the occurrence of cavitation. The spillway crest curve is also one of the factors affecting the occurrence of cavitation on the ogee-crested spillways. In this study, the ogee crested spillway that consists of three circular arcs upstream has been investigated. 5 different head ratios have been used. For this study, OpenFOAM software,...
Bounds for the Huckel energy of a graph
, Article Electronic Journal of Combinatorics ; Volume 16, Issue 1 R , 2009 ; 10778926 (ISSN) ; Koolen, J. H ; Yang, J. Y ; Sharif University of Technology
2009
Abstract
Let G be a graph on n vertices with r := [n/2] and let γ 1 ≥ · · · ≥ γ n be adjacency eigenvalues of G. Then the Ḧuckel energy of G, HE(G), is defined as [Equation presented] The concept of Hückel energy was introduced by Coulson as it gives a good approximation for the π-electron energy of molecular graphs. We obtain two upper bounds and a lower bound for HE(G). When n is even, it is shown that equality holds in both upper bounds if and only if G is a strongly regular graph with parameters (n, k, γ, μ) = (4t2 + 4t + 2, 2t2 + 3t + 1, t2 + 2t, t2 + 2t + 1), for positive integer t. Furthermore, we will give an infinite family of these strongly regular graph whose construction was communicated...
MGCN: Semi-supervised classification in multi-layer graphs with graph convolutional networks
, Article 11th IEEE/ACM International Conference on Advances in Social Networks Analysis and Mining, ASONAM 2019, 27 August 2019 through 30 August 2019 ; 2019 , Pages 208-211 ; 9781450368681 (ISBN) ; Baghshah, M. S ; Rabiee, H. R ; Sharif University of Technology
Association for Computing Machinery, Inc
2019
Abstract
Graph embedding is an important approach for graph analysis tasks such as node classification and link prediction. The goal of graph embedding is to find a low dimensional representation of graph nodes that preserves the graph information. Recent methods like Graph Convolutional Network (GCN) try to consider node attributes (if available) besides node relations and learn node embeddings for unsupervised and semi-supervised tasks on graphs. On the other hand, multi-layer graph analysis has been received attention recently. However, the existing methods for multi-layer graph embedding cannot incorporate all available information (like node attributes). Moreover, most of them consider either...
Hydrogen-rich water for green reduction of graphene oxide suspensions
, Article International Journal of Hydrogen Energy ; Volume 40, Issue 16 , 2015 , Pages 5553-5560 ; 03603199 (ISSN) ; Azimirad, R ; Gholizadeh, H. T ; Ghorbani, F ; Sharif University of Technology
Elsevier Ltd
2015
Abstract
Abstract H2-rich water as a green antioxidant was applied for deoxygenation of graphene oxide (GO) suspensions. The ability of H2-rich water for deoxygenation of GO sheets was found comparable to the ability of hydrazine (as a standard and powerful reductant), using X-ray photoelectron spectroscopy. In fact, the O/C ratio of GO sheets could be reduced from 0.51 to 0.21 and 0.16 by H2-rich water and hydrazine, respectively. More importantly, while C-N bond formation is one of the side effects of GO reduction by hydrazine, no chemical C-N bond was found on the H2-water-reduced GO (rGO) sheets. This also resulted in a better restoration of the graphitic structure of the H2-water-rGO, as...
Prediction of the degree of steel corrosion damage in reinforced concrete using field-based data by multi-gene genetic programming approach
, Article Soft Computing ; Volume 26, Issue 18 , 2022 , Pages 9481-9496 ; 14327643 (ISSN) ; Eftekhari, M ; Ghorbani, M ; Ehteshamzadeh, M ; Beirami, H ; Sharif University of Technology
Springer Science and Business Media Deutschland GmbH
2022
Abstract
Unanticipated failure of reinforced concrete structures due to corrosion of steel rebar embedded in concrete causes to increase the demand for finding methods to forecast the service life of concrete structures. In this field, the success of machine learning-based methods leads to the use of multi-gene genetic programming (MGGP) method for classifying the degree of corrosion destruction of steel in reinforced concrete in this paper. Despite the common application of MGGP that is the symbolic regression, in this research, MGGP was adapted to use in classification tasks. Accordingly, a large field database has been collected from different regions in the Persian Gulf for modeling of MGGP and...
Carbon-based nanocomposites: Distinguishing between deep-bed filtration and external filter cake by coupling core-scale mud-flow tests with computed tomography imaging
, Article Journal of Natural Gas Science and Engineering ; Volume 105 , 2022 ; 18755100 (ISSN) ; Fouji, M ; Ghorbani Heidarabad, R ; Aghaei, H ; Hajiabadi, S. H ; Bedrikovetsky, P ; Mahani, H ; Sharif University of Technology
Elsevier B.V
2022
Abstract
Although Multi-Walled Carbon NanoTubes (MWCNTs) are found to influence the rheological behavior of drilling fluids, there are yet some controversies regarding their performance towards reducing formation damage induced by the invasion of water-based drilling fluids (WBFs). To address this important question, we synthesized novel nanocomposite materials via modifying the MWCNT via varying the proportion of carboxylated MWCNTs to PolyVinyl Alcohol (PVA). These nanocomposites were then used to make nano-based drilling-fluids (NDFs). The performance of the NDFs was evaluated by a set of rheological behavior tests, filtration experiments, and core-scale mud flow tests. To distinguish between the...
Metabolomics fingerprinting of the human seminal plasma of asthenozoospermic patients
, Article Molecular Reproduction and Development ; Vol. 81, Issue. 1 , 2014 , pp. 84-86 ; ISSN: 1098-2795 ; Moazeni-Pourasil, R. S ; Jafarzadeh, N ; Savadi-Shiraz, E ; Sharif University of Technology
2014
Abstract
It is estimated that 20% of couples are infertile, and half of these infertility cases are linked to men. One of conditions that can affect male fertility is asthenozoospermia. We applied Raman spectroscopy to the analysis of the metabolome of the human seminal plasma, and used chemometrics on the patterns of Raman spectra obtained. Significant changes were observed in the metabolome of the human seminal plasma of asthenozoospermic patients
Enhancement of fungal delignification of rice straw by Trichoderma viride sp. to improve its saccharification
, Article Biochemical Engineering Journal ; Volume 101 , September , 2015 , Pages 77-84 ; 1369703X (ISSN) ; Karimi, M ; Biria, D ; Kariminia, H. R ; Jeihanipour, A ; Sharif University of Technology
Elsevier
2015
Abstract
Fungal delignification can be considered as a feasible process to pre-treat lignocellulosic biomass in biofuel production, if its performance is improved in terms of efficiency thorough a few modifications. In this study, Trichoderma viride was utilized to investigate the effect of wet-milling, addition of surfactant (Tween 80) and optimization of operating factors such as temperature, biomass to liquid medium ratio and glucose concentration on biodelignification of rice straw. Next, the enzymatic hydrolysis of pretreated biomass was studied at various pretreatment times. Results revealed that the wet milling and addition of surfactant increases the lignin removal about 15% and 11%,...
Immobilization of copper ions onto α-amidotriazole-functionalized magnetic nanoparticles and their application in the synthesis of triazole derivatives in water
, Article Applied Organometallic Chemistry ; Volume 30, Issue 6 , 2016 , Pages 488-493 ; 02682605 (ISSN) ; Ayati, S. E ; Firouzi, H. R ; Ghorbani, F ; Sharif University of Technology
John Wiley and Sons Ltd
2016
Abstract
A new heterogeneous copper catalyst was synthesized by immobilization of copper ions onto magnetic nanoparticles with a new ligand based on triazole. The catalyst was characterized using scanning and transmission electron microscopies, atomic absorption and Fourier transform infrared spectroscopies, and thermogravimetric, elemental and energy-dispersive X-ray analyses. The results confirmed that a good level of organic groups was immobilized on the magnetic nanoparticles. Huisgen cycloaddition reaction was chosen as a model reaction for the investigation of catalyst activity under green conditions. Phenylacetylene and benzyl bromide derivatives were used for the synthesis of triazoles. The...
, M.Sc. Thesis Sharif University of Technology ; Ghorbani, Mohammad (Supervisor)
Abstract
In the preceding years, hydroxyapatite (HA)-based coatings and scaffolds have been known as the best biomaterials for dental and orthopedics applications. Biocompatible and bioactive hydroxyapatite-based Coatings on metallic implants is one of the best methods for reaching both suitable mechanical properties and appropriate bioactivity, leading to better osseointegration and osteoblast proliferation. The ultimate goal of this project is characterization as well as mechanical and electrochemical behavior investigation of Hydroxyapatite- Chitosan nanocomposite coating by electrophoretic deposition (EPD) method on Plasma Electrolyte Oxidation (PEO) treated titanium substrates and Magnesium (Mg)...
Effects of initial precursor and microwave irradiation on step-by-step synthesis of zinc oxide nano-architectures
, Article Materials Letters ; Volume 67, Issue 1 , 2012 , Pages 342-345 ; 0167577X (ISSN) ; Samberg, J. P ; Ghorbani, H ; Kajbafvala, E ; Sadrnezhaad, S. K ; Sharif University of Technology
2012
Abstract
ZnO nano-architectures were produced with the aid of a fast, simple and low cost microwave-assisted synthesis method. Solid semispherical ZnO nanoparticles on the order of 600 nm in diameter along with rice-like ZnO nanorods 95 nm thick were produced from butanol, triethanolamine (TEA), and zinc acetate dihydrate. Solid spherical ZnO nano-architectures with an average diameter of 250 nm were produced from the same starting materials in addition to NaOH. X-ray diffraction, scanning electron microscopy, and transmission electron microscopy were used to characterize the ZnO nano-architectures as well as the precursor. This method is cheap, fast and simple; capable of producing large quantities...
RA-GCN: Graph convolutional network for disease prediction problems with imbalanced data
, Article Medical Image Analysis ; Volume 75 , 2022 ; 13618415 (ISSN) ; Kazi, A ; Soleymani Baghshah, M ; Rabiee, H. R ; Navab, N ; Sharif University of Technology
Elsevier B.V
2022
Abstract
Disease prediction is a well-known classification problem in medical applications. Graph Convolutional Networks (GCNs) provide a powerful tool for analyzing the patients’ features relative to each other. This can be achieved by modeling the problem as a graph node classification task, where each node is a patient. Due to the nature of such medical datasets, class imbalance is a prevalent issue in the field of disease prediction, where the distribution of classes is skewed. When the class imbalance is present in the data, the existing graph-based classifiers tend to be biased towards the major class(es) and neglect the samples in the minor class(es). On the other hand, the correct diagnosis...