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Preparation and Application of Superhydrophobic Melamine Formaldehyde Modified by Graphene Sorbent for Extraction of Chlorobenzenes from Aqueous Samples by Needle-trap Device
, M.Sc. Thesis Sharif University of Technology ; Bagheri, Habib (Supervisor)
Abstract
Superhydrophobic surfaces have attracted much attention in recent years due to their unique properties. Artificial superhydrophobic surfaces can be fabricated by employing chemical modifying a hierarchical structured surface (micro- and nanostructures) with a low surface free energy material. In this report, we used a simple one-step coating process to prepare superhydrophobic sorbents with a large surface area. Surface chemistry and porosity are fundamental parameters for an efficient sorbent capable of extracting low levels of analytes. Considering physical and chemical peroperties of chlorobenzenes, superhydrophobic materials make to be good sorbents. So in this project melamine...
Reduced graphene oxide–melamine formaldehyde as a highly efficient platform for needle trap microextraction of volatile organic compounds
, Article Microchemical Journal ; Volume 157 , 2020 ; Allahdadlalouni, M ; Baktash, M. Y ; Bagheri, H ; Sharif University of Technology
Elsevier Inc
2020
Abstract
A superhydrophobic extractive phase was prepared and packed in a needle trap microextraction device for extraction of volatile organic compounds, followed by their determination by gas chromatography. The superhydrophobic phase was prepared by surface modification of melamine formaldehyde (MF) sponge embedded by reduced graphene oxide (rGO). The overall properties of the modified MF along with its high sorption capacity and low cost fabrication were indicative of its feasibility to be highly suitable for extraction of organic pollutants. The determined water contact angle (>150o) from the surface of melamine formaldehyde–reduced graphene oxide (MF–rGO) revealed its high affinity toward...
Design oriented technique for mitigating position error due to shaft run-out in sinusoidal-rotor variable reluctance resolvers
, Article IET Electric Power Applications ; 2017 , Pages 132-141 ; 17518660 (ISSN) ; Tootoonchian, F ; Zare, F ; Sharif University of Technology
2017
Abstract
Variable reluctance (VR) resolvers have some distinguish features over wounded rotor resolvers that make them suitable for industrial applications. Among different types of VR resolvers, sinusoidal-rotor resolvers are preferred due to simple structure and high performance under eccentricities. However, their accuracy is affected by inevitable run-out error. As they work based on sinusoidal variation of coupling area between stator and rotor and under run-out error the coupling area is impaired. Hence, in this study, a new disk shape configuration is proposed for sinusoidal-rotor resolver that is robust against run-out error. Geometrical dimensions are calculated based on optimisations to...
Electronic Word of Mouth: Consumers' Motives for Participation in Online forums
,
M.Sc. Thesis
Sharif University of Technology
;
Modarres, Abdolhamid
(Supervisor)
Abstract
Consumers Communicate with each other to share information and feelings about products and brands. One important area to study personal influence in contemporary environment is online personal influence or electronic word of mouth. This study develops and tests consumers' motivations to participate in eWoM communication in online discussion forums. The main reason to choose Online forums is the huge number of eWoM discussions which occur in them. The main goal of this study is developing an aggregate framework for consumers' motives for opinion giving and seeking in online forums.To accomplish this goal we studied a comprehensive literature review, identified all motivations for WoM and...
Intelligent topology-oriented load shedding scheme in power systems
, Article 27th Iranian Conference on Electrical Engineering, ICEE 2019, 30 April 2019 through 2 May 2019 ; 2019 , Pages 652-656 ; 9781728115085 (ISBN) ; Ranjbar, A ; Faghihi, F ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2019
Abstract
Load shedding is a prevalent emergency control designed to prevent system blackouts. The higher complexity and lower predictability of modern power systems makes it difficult to rely on conventional load shedding schemes which shed loads in pre-defined steps without sufficient consideration of the actual system characteristics and the disturbance situations. In case of large disturbances, the power system stability can be improved by optimal load shedding in more effective load buses. Proposed scheme utilizes improved Power Flow Tracing method to determine the amount and location of load drops considering power system constraints. Numerical simulations conducted on IEEE 39 bus standard test...
Kneser graphs and their complements are hyperenergetic
, Article Match ; Volume 61, Issue 2 , 2009 , Pages 361-368 ; 03406253 (ISSN) ; Moazami, F ; Zare, S ; Sharif University of Technology
2009
Abstract
A graph G of order n is called hyperenergetic if E(G) > 2n -2, where E(G) is the energy of G. In this paper it is shown that Kneser graph K n:r is hyperenergetic for any naturals n and r > 2 with n > 2r + 1. Also we prove that for r > 2, the complement of Kneser graph, E(K n.r), is hyperenergetic
Intelligent topology-oriented LS scheme in power systems integrated with high wind power penetration
, Article IET Generation, Transmission and Distribution ; Volume 14, Issue 9 , 2020 , Pages 1684-1693 ; Ranjbar, A ; Faghihi, F ; Sharif University of Technology
Institution of Engineering and Technology
2020
Abstract
Load shedding (LS) is one of the most important protection schemes to prevent system blackout. In the case of largedisturbances, optimal LS in appropriate buses can effectively maintain the system stability. The higher complexity and lowerpredictability of modern power systems with high wind power penetration make it difficult to rely on conventional LS schemes,which shed a fixed, predetermined amount of load regardless of disturbance location. This study presents an intelligent LSscheme based on synchrophasor measurements that are adapted to both disturbance size and power system inertia. Theproposed scheme utilises improved power flow tracing method to determine the amount and location of...
Zero-sum magic labelings and null sets of regular graphs
, Article Electronic Journal of Combinatorics ; Vol. 21, issue. 2 , May , 2014 ; ISSN: 10778926 ; Rahmati, F ; Zare, S ; Sharif University of Technology
2014
Abstract
For every h ∈ ℕ, a graph G with the vertex set V (G) and the edge set E(G) is said to be h-magic if there exists a labeling l: E(G) → ℤh{0} such that the induced vertex labeling s: V (G) → ℤh, defined by s(v) = Puv∈E(G) l(uv) is a constant map. When this constant is zero, we say that G admits a zero-sum h-magic labeling. The null set of a graph G, denoted by N(G), is the set of all natural numbers h ∈ ℕ such that G admits a zero-sum h-magic labeling. In 2012, the null sets of 3-regular graphs were determined. In this paper we show that if G is an r-regular graph, then for even r (r > 2), N(G) = ℕ and for odd r (r ≠ 5), ℕ {2, 4} ⊆ N(G). Moreover, we prove that if r is odd and G is a 2-edge...
Performance evaluation of disk type variable reluctance resolvers
, Article IEEE Sensors Journal ; Volume 17, Issue 13 , 2017 , Pages 4037-4045 ; 1530437X (ISSN) ; Alipour Sarabi, R ; Tootoonchian, F ; Zare, F ; Sharif University of Technology
2017
Abstract
In this paper, a new disk type variable reluctance (DTVR) resolver is introduced. The proposed resolver works based on the sinusoidal variation of the coupling area between stator and rotor. An analytical model based on winding function theory is proposed for the performance analysis of the sensor. Then, the influence of stator slot shape, radial and peripheral slot width, pole numbers, and slot skewing and harmonic injection into the rotor couture on the accuracy of the proposed resolver is examined. The 3-D time stepping finite element method is used to show the effect of optimizations. Finally, the prototypes of the two-pole, four-pole, and eight-pole DTVR resolvers are constructed and...
Project Planning and Management Under Resource Constraint and Stochastic Activity Duration
, M.Sc. Thesis Sharif University of Technology ; Kianfar, Farhad (Supervisor)
Abstract
Most of the researches on project planning and scheduling have supposed that there is a complete and fixed information about the activities duration and amount of resources needed for project, but in reality we face lots of uncertainty in activities duration and required resources. In previous researches there are some cases which lead to more than one schedule for project, but in most of them they offer no solution for choosing between the schedules. In this project we are trying to make a nonlinear model of project environment by using Weibull distribution as activities duration and then we determine the input information by using the methods of probability encoding in decision analysis....
Heterogeneous SBA-15-supported oxoperoxomolybdenum(VI) complex for enhanced olefin epoxidation
, Article Catalysis Communications ; Volume 88 , 2017 , Pages 9-12 ; 15667367 (ISSN) ; Moradi Shoeili, Z ; Ashouri, F ; Bagherzadeh, M ; Sharif University of Technology
2017
Abstract
Heterogeneous nanoscale catalyst was successfully synthesized via anchoring of oxoperoxo molybdenum(VI) complex on the chloro-functionalized SBA-15. The mesoporous nanomaterials, MoO3(sal-phz)/SBA-15 (where sal-phz is salicylidene 2-picoloyl hydrazine) were identified by several characterization techniques. MoO3(sal-phz)/SBA-15 and MoO3(sal-phz) were also treated as catalysts in the olefins epoxidation reactions. Both homogenous and heterogeneous catalysts exhibit outstanding activity and selectivity for epoxide with tert-BuOOH in decane as oxidant at 95 °C. In addition, the heterogeneous nanocatalyst was chemically stable and can be efficiently reused for at least six cycles without a...
The assessment of efficient representation of drug features using deep learning for drug repositioning
, Article BMC Bioinformatics ; Volume 20, Issue 1 , 2019 ; 14712105 (ISSN) ; Ghadirinia, M ; Sharifi Zarchi, A ; Zare Mirakabad, F ; Sharif University of Technology
BioMed Central Ltd
2019
Abstract
Background: De novo drug discovery is a time-consuming and expensive process. Nowadays, drug repositioning is utilized as a common strategy to discover a new drug indication for existing drugs. This strategy is mostly used in cases with a limited number of candidate pairs of drugs and diseases. In other words, they are not scalable to a large number of drugs and diseases. Most of the in-silico methods mainly focus on linear approaches while non-linear models are still scarce for new indication predictions. Therefore, applying non-linear computational approaches can offer an opportunity to predict possible drug repositioning candidates. Results: In this study, we present a non-linear method...
Valence bond phases in S = 1/2 Kane-Mele-Heisenberg model
, Article Journal of Physics Condensed Matter ; Vol. 26, issue. 45 , 2014 ; ISSN: 09538984 ; Mosadeq, H ; Shahbazi, F ; Jafari, S. A ; Sharif University of Technology
2014
Abstract
The phase diagram of the Kane-Mele-Heisenberg model in a classical limit [47] contains disordered regions in the coupling space, as the result of competition between different terms in the Hamiltonian, leading to frustration in finding a unique ground state. In this work we explore the nature of these phases in the quantum limit, for a S = 1/2. Employing exact diagonalization in Sz and nearest neighbour valence bond bases, and bond and plaquette valence bond mean field theories, we show that the disordered regions are divided into ordered quantum states in the form of plaquette valence bond crystals and staggered dimerized phases
Influence of heavy nanocrystals on spermatozoa and fertility of mammals
, Article Materials Science and Engineering C ; Volume 69 , 2016 , Pages 52-59 ; 09284931 (ISSN) ; Hashemi, E ; Zare, H ; Shamsara, M ; Taghavinia, N ; Heidari, F ; Sharif University of Technology
Elsevier Ltd
2016
Abstract
In recent years, quantum dots (QDs) have been widely used in upcoming nanotechnology-based solar cells, light-emitting diodes and even bioimaging, due to their tunable optical properties and excellent quantum yields. But, such nanostructures are currently constituted by heavy elements which can threat the human health and living environment. Hence, in this work, the in vivo effects of CdTe nanocrystals (NCs) (as one of the promising QDs) on spermatozoa of male mice and subsequently on fertility of female mice were investigated, for the first time. To do this, CdTe NCs were synthesized through an environment-friendly (aqueous-based solution) method. The sperm cells presented a high potential...
Surveying Philosophical Arguments on "Origination of The Universe" based on the views of: W.L.Craig, Q.Smith and Allamah S.M.H Al-Tabatabaie
,
M.Sc. Thesis
Sharif University of Technology
;
Hosseini, Hassan
(Supervisor)
Abstract
The problem of Origination of The Universe is one of the most important issues in the history of philosophy whether in western edition or in Islamic thought. The most problematic aspect of the Origination is Temporal Origination. From about 30 years ago as a result of the works of a famous American philosopher William Lane Craig, the debate between temporality and Eternity of the Universe became a fresh topic in western philosophy. In this research we want to survey the philosophical arguments for and against the temporality of the Universe based on the views of: W.L.Craig, Q.Smith and Allamah S.M.H Al-Tabatabaie.
Influence of martensite volume fraction on tensile properties of triple phase ferrite-bainite-martensite steels
, Article Materials Science and Engineering A ; Volume 530, Issue 1 , 2011 , Pages 440-445 ; 09215093 (ISSN) ; Ekrami, A ; Sharif University of Technology
2011
Abstract
This paper presents the effect of martensite volume fraction (VM) on mechanical properties of AISI 4340 steel with ferrite-bainite-martensite microstructures. The steel bars were austenitized at 900°C for 1h followed by intercritical annealing at 740°C for 100min and quenching into a salt bath with temperature of 300°C and holding at different times to obtain triple phase (TP) microstructures with 34vol.% fraction ferrite and various martensite (or bainite) contents. Presence of three phases in adjacent to each other was confirmed by metallographic analysis and TEM studies. TEM observation also indicates higher density of dislocations within ferrite near martensite colonies compared to that...
Effect of martensite volume fraction on work hardening behavior of triple phase (TP) steels
, Article Materials Science and Engineering A ; Volume 528, Issue 13-14 , 2011 , Pages 4422-4426 ; 09215093 (ISSN) ; Ekrami, A ; Sharif University of Technology
2011
Abstract
The strain hardening behavior of AISI 4340 steel with dual phase (DP) and triple phase (TP) microstructures with constant ferrite volume fractions of 34% was investigated. The microstructures of specimens were analyzed using an optical microscope. The tensile flow behavior of all the samples was explained using Holloman equation. Results showed that in both DP and TP steels, work hardening takes place in two stages. The onset strain of second stage of work hardening and Holloman equation parameters (work hardening exponent and strength coefficient) in both stages were increased with the increase of martensite volume fraction in TP steels. At first stage of work hardening, ferrite phase...
Investigation on Interfacial Reactions in Aluminium to Copper Resistance Spot Welding
, M.Sc. Thesis Sharif University of Technology ; Pouranvari, Majid (Supervisor)
Abstract
With the development of electrical engineering and the electrical industry, the use of copper and its alloys has grown tremendously. On the other hand, with development and modern industry, it will be difficult to meet the requirements such as high performance, cost reduction and weight reduction of the structure if only one metal material is used in the production of the desired component or structure. Aluminum can be used in combination with copper because of its properties such as high thermal and electrical conductivity. Al/Cu bonding is used in industries such as microelectronics, automobiles and batteries. This study has investigated parametrically the feasibility of uneven bonding of...
6DOF Flight Dynamics Modeling of a Flexible Flapping wing using Unsteady Aerodynamics
, Ph.D. Dissertation Sharif University of Technology ; Pourtakdoust, Hossein (Supervisor)
Abstract
A complete 6DOF flight dynamic model of an elastic flapping wing (EFW), integrated with unsteady aerodynamic theory is developed. In this respect, initially efficient high fidelity modules for EFW structural dynamics (SD) as well as unsteady aerodynamics loadings (UAL) to be coupled with its flight dynamics are prepared. A modal approach is followed to model structural dynamics of plain and 3D EFWs. This is in contrast with the Euler-Bernoulli beam theory that is mostly utilized for SD in the existing literature. In addition, due to the possibility of large wing deformations as well as the existence of non-linear displacement regime for realistic EFW flights, non-linear modal approaches such...
Design An Efficient Method for Solving Integer Programming by Lagrangian Relaxation
, M.Sc. Thesis Sharif University of Technology ; Eshghi, Kourosh (Supervisor)
Abstract
The subgradient method is one of the most favoriate methods to solve discrete optimization problems. The Easy Implementation and flexibility enbles us to solve a vast types of complicated combinatorial optimization problems. However, the algorithm can be improved by adjusting its parameters and steps.In present research, we present a heuristic structure to modify and improve the algorithm. Then, the proposed algorithm has tested on special classes of discrete optimization problems such as Generealized Assignment and Uncapacitated Warehouse location problems. The results show that the proposed algorithm can improve the efficiency of the classic form of subgradient method.The three main...