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DFT study of the interaction of thymine with Cu+ and Zn 2+
, Article Scientia Iranica ; Volume 16, Issue 2 C , 2009 , Pages 75-80 ; 10263098 (ISSN) ; Fattahi, A ; Sharif University of Technology
2009
Abstract
Interaction of the DNA thymine base with Cu+ and Zn3+ was studied to explore: a) The metal binding energy (MIA) of thymine with Cu+ and Zn2+ and b) The possible correlation between charge transfer and MIAs. The gas-phase Cu+ and Zn2+ affinities of thymine, as well as the Mulliken charges, on the complexed metal cations were both determined at the same computational level, including the density functional level and employing the hybrid B3LYP exchange correlation potential in connection with the 6-311++G (d,p) basis set. All the molecular complexes were obtained by interaction between the most stable tautomer of thymine and two transition mono and divalent (Cu+, Zn2+) metal ions. To probe all...
Thermochemical Properties of Thymine & Deoxythymidine
, M.Sc. Thesis Sharif University of Technology ; Fattahi, Alireza (Supervisor)
Abstract
Nowadays, there is no doubt about the importance of investigation of physicochemical properties of nucleosides in order to determine the structure of these biopolymers. Nucleotides have a variety of roles in cellular metabolism. They are the constituents of nucleic acids: deoxyribonucleic acid (DNA) and ribonucleic acid (RNA), the molecular repositories of genetic information. The metal ions play a significant role in several biological processes. Synthesis, replication, and cleavage of DNA and RNA as well as their structure integrity are affected by the presence of these ionized metals in the cell nucleus. To understand the role of cations in the biophysics of DNA, it is necessary first to...
Theoretical Investigation of the Structural and Electronic Properties of Ionic Liquids and Their Adsorption on Graphene and Boron-Nitride Surfaces; Synthesis of α-Aminophosphonates Using Fe3O4 Magnetic Nanoparticles
, Ph.D. Dissertation Sharif University of Technology ; Fattahi, Alireza (Supervisor) ; Mahmoodi Hashemi, Mohammad (Supervisor)
Abstract
This thesis is divided into three parts: In part I, structure and electronic properties of ionic liquids based on N7, N9-dimethylguaninium cation and α-amino acid (Gly, His, Phe, Try, and Tyr) anions and also ionic liquids based on 1-ethyl-3-methylimidazolium [emim]+ cation and alkyl-trifluoroborate ([RBF3]-, R=n-CmH2m+1 (m=1-5)) anions were discussed at the DFT(B3LYP)/6-311++G(d,p) level of theory. Then, the effect of chain length in anion on the nature and strength of interaction between cation and anion was investigated. Our results indicated that interaction energy values decrease with the increase in side chain size in anion. NBO and QTAIM results indicated that the interaction in these...
On exponential flocking to the virtual leader in network of agents with double-integrator dynamics
, Article Journal of Dynamic Systems, Measurement and Control, Transactions of the ASME ; Volume 135, Issue 3 , 2013 ; 00220434 (ISSN) ; Haeri, M ; Sharif University of Technology
2013
Abstract
This paper considers flocking to the virtual leader in network of agents with double-integrator. A locally linear algorithm is employed which guarantees exponential flocking to the virtual leader. A lower bound for flocking rate is calculated which is independent of the initial conditions. Simulations are provided to validate the result and it is shown that the calculated rate is not over bound the actual convergence rate. The effect of coefficients of algorithm is investigated and it is shown that the similar results can be inferred from the calculated formula for the convergence rate. Copyright
Optimization of multi-objective redundancy allocation problem with non-homogeneous components
, Article Computers and Industrial Engineering ; Volume 108 , 2017 , Pages 111-123 ; 03608352 (ISSN) ; Feizabadi, M ; Sharif University of Technology
Elsevier Ltd
2017
Abstract
In many real world optimization problems, including Redundancy Allocation Problem (RAP), there is a need to optimize more than one objective function simultaneously. In this paper, a new multi-objective formulation is presented for the RAP by considering the reliability and cost of the system as the objective functions. The previous formulations have been proposed based on the assumption that all components of a subsystem are homogeneous. This constraint leads to an increase in the designing cost and prevents from reaching to higher quantities of the system reliability. The presented formulation in this research provides an opportunity for the subsystems components to be non-homogeneous in...
A modified low rank learning based on iterative nuclear weighting in ripplet transform for denoising MR images
, Article 29th Iranian Conference on Electrical Engineering, ICEE 2021, 18 May 2021 through 20 May 2021 ; 2021 , Pages 912-916 ; 9781665433655 (ISBN) ; Nejati Jahromi, M ; Nouri, M ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2021
Abstract
In recent studies, several methods have been suggested to decrease noise of magnetic resonance image (MRI) in order to raise the peak signal-to-noise ratio (PSNR) and the structural similarity index (SSIM). In this paper, we propose a novel method based on a minimization problem in Ripplet domain that uses singular value decomposition (SVD) in low rank learning to eliminate the noise of MRI images. We reschedule the weighted nuclear norm minimization (WNNM) problem in any edges of Ripplet domain transform and using an adaptive weighting structure to denoise the patches of Ripplet component matrix. The parameters of the proposed method are divided into two groups, some of them are calculated...
Optimized midterm preventive maintenance outage scheduling of thermal generating units
, Article IEEE Transactions on Power Systems ; Vol. 27, issue. 3 , 2012 , p. 1354-1365 ; ISSN: 08858950 ; Fotuhi-Firuzabad, M ; Parvania, M ; Sharif University of Technology
2012
Abstract
This paper addresses the midterm preventive maintenance outage scheduling problem of thermal generating units which is becoming increasingly important due to the aging of power generation fleet. In this context, a novel midterm preventive maintenance outage scheduler is proposed based on decision tree and mixed integer linear formation which explicitly considers the thermal units aging momentum in terms of failure rate. This allows the system operators to determine the thermal units' maintenance outage window based on the cost/benefit analysis of preventive maintenance tasks while optimizing the time interval between consecutive maintenance tasks. Additionally, the division of the year-long...
Free vibration analysis of Mindlin plates partially resting on Pasternak foundation
, Article International Journal of Mechanical Sciences ; Volume 75 , 2013 , Pages 1-7 ; 00207403 (ISSN) ; Aghdam, M. M ; Fallah, A ; Sharif University of Technology
2013
Abstract
In this paper, the generalized differential quadrature (GDQ) method is used to study free vibration of moderately thick rectangular plate partially resting on Pasternak foundation. The foundation is considered to support the plate either completely or partially. The governing equations which consist of a system of partial differential equations (PDEs) are obtained based on the first-order shear deformation theory. Various combinations of simply supported, clamped and free boundary conditions are considered. Application of the GDQ method to the governing PDEs resulted in a system of algebraic equations. Solution of this system with accordance to the considered boundary conditions leads to an...
Optimized midterm preventive maintenance outage scheduling of thermal generating units
, Article IEEE Transactions on Power Systems ; Volume 27, Issue 3 , 2012 , Pages 1354-1365 ; 08858950 (ISSN) ; Fotuhi Firuzabad, M ; Parvania, M ; Sharif University of Technology
2012
Abstract
This paper addresses the midterm preventive maintenance outage scheduling problem of thermal generating units which is becoming increasingly important due to the aging of power generation fleet. In this context, a novel midterm preventive maintenance outage scheduler is proposed based on decision tree and mixed integer linear formation which explicitly considers the thermal units aging momentum in terms of failure rate. This allows the system operators to determine the thermal units' maintenance outage window based on the cost/benefit analysis of preventive maintenance tasks while optimizing the time interval between consecutive maintenance tasks. Additionally, the division of the year-long...
Cause-and-effect relationships affecting distribution loss management
, Article IEEE PES Innovative Smart Grid Technologies Conference Europe, ISGT Europe, 11 October 2010 through 13 October 2010 ; October , 2010 ; 9781424485109 (ISBN) ; Ehsan, M ; Masjed Jamei, M ; Sharif University of Technology
2010
Abstract
There are a lot of parameters which are decisive in distribution loss management, such as demand value, energy price, etc. In this paper the cause-and-effect relationships among some of these variables are clearly described. The study demonstrates how a variable in the model will change, if an alteration in one of the other variables occurs. The power system variables considered in this study include energy and loss prices, generation and demand values, distribution loss, distribution system age, number of customers connected to the smart grid, distribution network revenue, and so forth. The smart grid impacts can be studied from two different aspects: 1) the communication infrastructure...
Optimizing the operation of current differential protection by power differential relay for three phase transformer
, Article 2006 IEEE GCC Conference, GCC 2006, Manama, 20 March 2006 through 22 March 2006 ; 2006 ; 9780780395909 (ISBN) ; Esmi Jahromi, M ; Ranjbar, A. M ; Sharif University of Technology
2006
Abstract
To avoid the needless trip by magnetizing inrush current, the second harmonic component is commonly used for blocking differential relay in power transformers. However, the main problems of the current comparison method are in the very high inrush currents and relatively small fault currents regarding winding short circuits. Also The second harmonic component in fault current is increased in long lines which may blocks the relay operation. This paper describes a method to discriminate internal fault from inrush current and faults with a high second harmonic component by the sum of active power flowing into the transformer from each terminal. The average power is almost negligible for...
Selective oxidation of sulfides to sulfoxides by a molybdate-based catalyst using 30% hydrogen peroxide
, Article Catalysis Communications ; Vol. 52, issue , July , 2014 , pp. 16-21 ; ISSN: 15667367 ; Shakourian-Fard, M ; Hashemi, M. M ; Sharif University of Technology
2014
Abstract
An efficient method is reported for selective oxidation of various types of sulfides to sulfoxides and sulfones in good to high yields using 30% H 2O2 in the presence of catalytic amounts of molybdate-based catalyst in acetonitrile as solvent at room temperature. The catalyst can be easily recovered and reused for seven reaction cycles without considerable loss of activity
Design of silica supported task-specific ionic liquid catalyst system for oxidation of cyclohexene to adipic acid with 30% H 2O 2
, Article Catalysis Communications ; Volume 26 , September , 2012 , Pages 54-57 ; 15667367 (ISSN) ; Hashemi, M. M ; Shakourian Fard, M ; Sharif University of Technology
Elsevier
2012
Abstract
1-Butyl-3-methylimidazolium tungstate ([BMIm] 2WO 4) ionic liquid supported onto silica sulphamic acid demonstrated desirable performance for oxidation of cyclohexene to adipic acid. Simple experimental procedure, easy product isolation, catalyst recovery and reusability are some attractive features of this protocol
Effect of electrical parameters on morphology, chemical composition, and photoactivity of the nano-porous titania layers synthesized by pulse-microarc oxidation
, Article Electrochimica Acta ; Volume 55, Issue 8 , 2010 , Pages 2760-2766 ; 00134686 (ISSN) ; Moshfegh, A. Z ; Golestani Fard, F
2010
Abstract
TiO2 layers were grown via pulse type microarc oxidation process under different applied voltages, frequencies, and duty cycles. Surface chemical composition and phase structure of the synthesized layers were studied utilizing X-ray photoelectron spectroscopy (XPS) and X-ray diffraction (XRD). Furthermore, scanning electron microscope (SEM) and atomic force microscope (AFM) were employed to investigate surface morphology and topography of the layers. It was revealed that the layers had a porous structure with both anatase and rutile phases. The anatase relative content in the layers increased with the applied frequency; meanwhile, it decreased with duty cycle at low applied voltages, but...
Effect of electropulsing on microstructure and hardness of cold-rolled low carbon steel
, Article Journal of Materials Research and Technology ; Volume 8, Issue 3 , 2019 , Pages 3114-3125 ; 22387854 (ISSN) ; Kazeminezhad, M ; Sharif University of Technology
Elsevier Editora Ltda
2019
Abstract
The application of electropulsing treatment (EPT) is studied on the microstructure and hardness of cold-rolled low carbon steel. The effects of electrical pulses on the grain refinement, precipitate size evolution and hardness are investigated. It is found that applying electrical pulse decreases the grain and precipitate size and increases the hardness in the early stages of electropulsing, but the grain and precipitate size is increased and the hardness is decreased by continuing electropulsing. Also, the effect of electropulsing treatment variables as well as treated time and number of periods are discussed. It is demonstrated that increasing treated time can accelerate achieving maximum...
Optimized sectionalizing switch placement strategy in distribution systems
, Article IEEE Transactions on Power Delivery ; Vol. 27, issue. 1 , 2012 , p. 362-370 ; ISSN: 08858977 ; Fotuhi-Firuzabad M ; Parvania, M ; Mosleh, M ; Sharif University of Technology
2012
Abstract
Automation is acknowledged by distribution utilities as a successful investment strategy to enhance reliability and operation efficiency. However, practical approaches that can handle the complex decision-making process faced by decision makers to justify the long-term financial effects of distribution automation have remained scarce. An automated and remote-controlled sectionalizing switch play a fundamental role in an automated distribution network. This paper introduces a new optimization approach for distribution automation in terms of automated and remotely controlled sectionalizing switch placement. Mixed-integer linear programming (MILP) is utilized to model the problem. The proposed...
Optimized sectionalizing switch placement strategy in distribution systems
, Article IEEE Transactions on Power Delivery ; Volume 27, Issue 1 , 2012 , Pages 362-370 ; 08858977 (ISSN) ; Fotuhi Firuzabad, M ; Parvania, M ; Mosleh, M ; Sharif University of Technology
2012
Abstract
Automation is acknowledged by distribution utilities as a successful investment strategy to enhance reliability and operation efficiency. However, practical approaches that can handle the complex decision-making process faced by decision makers to justify the long-term financial effects of distribution automation have remained scarce. An automated and remote-controlled sectionalizing switch play a fundamental role in an automated distribution network. This paper introduces a new optimization approach for distribution automation in terms of automated and remotely controlled sectionalizing switch placement. Mixed-integer linear programming (MILP) is utilized to model the problem. The proposed...
From loss allocation to loss cost allocation: a comparative study of different loss cost allocation methods
, Article International Transactions on Electrical Energy Systems ; Volume 23, Issue 4 , 2013 , Pages 586-600 ; 20507038 (ISSN) ; Ehsan, M ; Fotuhi Firuzabad, M ; Parvania, M ; Sharif University of Technology
2013
Abstract
As a high proportion of the total generated electricity energy and the power system costs is due to the power losses in lines, allocating the loss and associated cost to the system loads and generating units is a substantial issue in deregulated power systems. The procedure to accomplish this cost allocation is designated as 'loss cost allocation' (LCA). So far, a number of LCA methods have been proposed for transmission networks. A few papers have compared different loss allocation methods, which are the methods which calculate the loss (and not necessarily the loss cost) allocated to the loads and generating units. However, this paper presents a comparative study of LCA methods. In this...
Distribution loss allocation for radial systems including dgs
, Article IEEE Transactions on Power Delivery ; Vol. 29, issue. 1 , 2014 , pp. 72-80 ; ISSN: 08858977 ; Mahmoodzadeh, Z ; Ehsan, M ; Sharif University of Technology
2014
Abstract
Due to the liberalization of the electricity market and the introduction of distributed generation (DG), the importance of distribution loss allocation (LA) has increased. This paper presents a new method for distribution power LA in radial systems. The proposed method, which is based on the results of power flow and considers active and reactive power flows of lines for LA, is composed of three steps. In the first step, starting from the source nodes (i.e., the nodes whose generation is more than their load), the power loss allocated to all nodes is calculated and then the power loss allocated to the loads connected to each node is obtained. In the next step, the total power loss is...
Reflected shock tube experiments on aeroacoustic signature of hot jets
, Article Journal of Mechanical Science and Technology ; Volume 31, Issue 8 , 2017 , Pages 3811-3820 ; 1738494X (ISSN) ; Ebrahimi, M ; Ghorbanian, K ; Sharif University of Technology
2017
Abstract
We used a reflected shock tube to investigate the acoustic signature of a hot jet at the far-field. Experiments were performed at Mach = 1.4 and a total temperature of Tt = 950 Kelvin. Far-field acoustic signatures of the hot jet at six polar angles θ = 15˚ to θ = 90˚ from the jet axis) were measured and imaged by the means of continuous wavelet transform in scalograms. The results were compared with experiments from a steady test facility at similar test conditions. Further, the primary characteristics of noise events in jet far-field were compared with analytical models considering wavepacket as the main source of jet noise. The results indicate that higher frequency events at θ = 90˚...