Search for: calculation
Total 377 records
Article Informatica (Ljubljana) ; Volume 35, Issue 1 , 2011 , Pages 39-49 ; 03505596 (ISSN) ; Salaun, G ; Sharif University of Technology
Choreography description languages aim at specifying from a global point of view interactions among a set of services involved in a new system. From this specification, local implementations or peers can be automatically generated. Generation of peers that precisely implement the choreography specification is not always possible: This problem is known as realizability. When peers corresponding to this specification are being executed we may want to modify the choreography specification and reconfigure dynamically the system. This is the case for instance if we add or remove interactions due to the addition of functionalities to the system at hand or the loss of a service. In this article, we...
Article 2009 14th International CSI Computer Conference, CSICC 2009, 20 October 2009 through 21 October 2009 ; 2009 , Pages 140-145 ; 9781424442621 (ISBN) ; Mirian Hosseinabadi, S. H ; Sharif University of Technology
In this paper, we introduce a refinement approach to develop probabilistic programs formally. To achieve this goal, we first present a way to specify probabilistic programs in a Z-based notation. We then use an existing method of translating Z into a refinement calculus to transform our Z-style specifications of probabilistic programs into specification statements of the refinement calculus. We finally add new laws to the refinement calculus helping us to refine the resulting specification statements into probabilistic choice constructs of a probabilistic imperative language. In this way, we will provide a completely formal way for developing probabilistic programs. ©2009 IEEE
A joint experimental and theoretical study of kinetic and mechanism of rearrangement of allyl p-tolyl ether, Article Journal of Molecular Structure: THEOCHEM ; Volume 893, Issue 1-3 , 2009 , Pages 73-76 ; 01661280 (ISSN) ; Haqgu, M ; Talebi, A ; Gholami, M. R ; Sharif University of Technology
A joint theoretical and experimental study of the kinetic and mechanism of the rearrangement of allyl p-tolyl ether was performed in order to study the kinetic and mechanism of the reaction. Experimental studies were performed in gas phase over a temperature range of 493.15-533.15 K. The experimental Arrhenius parameters of this reaction were measured to be Ea = 36.08 kcal mol-1, ΔS# = -7.88 cal mol-1 K-1, and Log A = 11.74, experimentally. Using GC for the mixture of the reaction with and without cyclohexene demonstrated that the reaction is clean without any radical intermediates. The experimental results show that the studied reaction is unimolecular and proceeds through a concerted...
Article ChemBioChem ; 2020 ; Teixeira, J. M. C ; Paniagua, J. C ; Pons, M ; Sharif University of Technology
Wiley-VCH Verlag 2020
Coupling of side chain dynamics over long distances is an important component of allostery. Methionine side chains show the largest intrinsic flexibility among methyl-containing residues but the actual degree of conformational averaging depends on the proximity and mobility of neighboring residues. The 13C NMR chemical shifts of the methyl groups of methionine residues located at long distances in the same protein show a similar scaling with respect to the values predicted from the static X-ray structure by quantum methods. This results in a good linear correlation between calculated and observed chemical shifts. The slope is protein dependent and ranges from zero for the highly flexible...
A study of glycine-based dithiocarbamates as effective corrosion inhibitors for cold rolled carbon steel in HCl solutions, Article Surfaces and Interfaces ; Volume 21 , 2020 ; Shockravi, A ; Mokarami Ghartavol, H ; Ziyaei Halimehjani, A ; Ostadrahimi, M ; Mirhosseini, S. M ; Behzadi, H ; Ghorbani, M ; Sharif University of Technology
Elsevier B.V 2020
The corrosion inhibition of glycine-based dithiocarbamates with benzyl (BDTC) and propyl (PDTC) groups were investigated for cold rolled carbon steel (CRS) in 0.5 M HCl, indicating that the compounds as mixed type inhibitors significantly reduced the corrosion rate of the CRS due to the formation of a stable protective film on the metal surface. As confirmed by ATR-FTIR, SEM, AFM, XPS and theoretical studies, chemically adsorbed BDTC molecule is a better corrosion inhibitor with higher corrosion efficiency of about 98% at room temperature and a better thermal stability attributed to the Fe-S and Fe-N bindings, and in addition, to the presence of the benzene ring in the molecular structure. ©...
Article Photonic Crystal Materials and Devices VII, San Jose, CA, 21 January 2008 through 23 January 2008 ; Volume 6901 , 2008 ; 0277786X (ISSN); 9780819470768 (ISBN) ; Khorasani, S ; Latifi, H ; Atabaki, A. H ; The International Society for Optical Engineering (SPIE) ; Sharif University of Technology
When the periodic permittivity of two-dimensional (2D) photonic crystal (PC) can be separated in x- and y- coordinates, one can consider the structure as two separate 1D photonic crystals, one of them being periodic in x coordinate and the other in y coordinate. If it is possible to find a proper separable permittivity function, we can approximate a 2D PC with two distinct 1D structures. One of the advantages is rapid calculation the density of state of a 2D PC. In this article an analytical calculation of the density of states for such a 2D PC has been done with the aim of taking this advantage. For calculating the density of states we use the effective resonance approach to analyze the 1D...
Article 6th IEEE International Symposium on Signal Processing and Information Technology, ISSPIT 2006, Vancouver, BC, 27 August 2006 through 30 August 2006 ; 2006 , Pages 908-913 ; 0780397541 (ISBN); 9780780397545 (ISBN) ; Babaeizadeh, M ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc 2006
Block motion estimation is an important field of video processing. This paper presents a new scheme to reach in faster block motion estimation based on motion prediction. The scheme exploits an adaptive filter to predict the block motion from its spatio-temporal motion compensated adjacent blocks, the predicted motion determines the initial candidate block for search methods with biased search center, in special case of partial distortion search, this strategy reduces search time by preventing from complete distortion calculation for more loser candidates, after comparison of three conventional adaptive filters, a normalized least mean square filter with convergence monitoring is recommended...
Article Insight: Non-Destructive Testing and Condition Monitoring ; Volume 46, Issue 7 , 2004 , Pages 396-398 ; 13542575 (ISSN) ; Rastkhah, N ; Kermani, A ; Seidi, M ; Movafeghi, A ; Sharif University of Technology
Wall thickness measurement and deterioration determination of 6 and 10 inch pipes due to corrosion/erosion/pitting was evaluated by using radiographic film density measurements. Special reference blocks were prepared with defined step wall reductions and artificial defects. Gamma radiography with a Ir-192 source was used. A double-wall technique with longitudinal film arrangement was used for this purpose. Formulae were developed from the experiments for numerical calculations. It was observed that this method can determine remaining wall thickness as well as pitting corrosion in insulated and non-insulated pipes with differential and absolute density measurements. The purpose of the work...
A joint experimental and computational study on the kinetic and mechanism of diallyl disulfide pyrolysis in the gas phase, Article Chemical Physics ; Volume 301, Issue 1 , 2004 , Pages 45-51 ; 03010104 (ISSN) ; Izadyar, M ; Sharif University of Technology
A combined theoretical and experimental kinetic and mechanism of diallyl disulfide pyrolysis reaction in the gas phase was studied in a static system over the temperature range of 586.7-621.2 K and a total pressure of 72 Torr in the presence of cyclohexene as radicals inhibitor. The experimental results show that the reaction is homogeneous, unimolecular and proceeds through a radical mechanism. Theoretical calculations at the B3LYP level using the 6-31G*, 6-31++G* and 6-311++G* basis sets confirm the radical mechanism for the diallyl disulfide pyrolysis. The calculated kinetic and activation parameters especially at the B3LYP/6-31G* level are in good agreement with the experimental data. ©...
DFT studies of pyridine corrosion inhibitors in electrical double layer: Solvent, substrate, and electric field effects, Article Chemical Physics ; Volume 299, Issue 1 , 2004 , Pages 131-137 ; 03010104 (ISSN) ; Arshadi, M. R ; Sharif University of Technology
The molecular behavior of some pyridine derivatives as corrosion inhibitors of iron and aluminum in acid media, were studied quantum electrochemically. The calculations were made for three conditions; isolated inhibitor molecule, metal cluster, and finally polarized continuum media. It is concluded that for aluminum the vertical adsorption through nitrogen atom is prevailing, while for iron both vertical and planar adsorptions (through π electrons of aromatic ring) are possible, but the vertical is predominant. The inhibitor chemical potential (μ) and the extent of charge transfer (ΔN) to the metal were determined. A linear correlation between each of these and the inhibition efficiencies...
Article Journal of Chemical Research ; Issue 9 , 2004 , Pages 585-588 ; 03082342 (ISSN) ; Jahangir, A. H ; Gholami, M. R ; Sharif University of Technology
Scientific Reviews Ltd 2004
The mechanism and kinetic aspects of the retro-ene reaction of allyl n-butyl sulfide and its deuterated derivative were studied using four different types of density functional theory (DFT) methods with eight different levels of the basis sets. Vibrational frequency analysis confirmed that the stationary points include the transition state (TS) structure with only one imaginary frequency. Mechanistic studies on the retro-ene process rejected the step-wise mechanism and confirmed that the reaction proceeds through a six-centered cyclic transition state. Theoretical calculations show that propene elimination from the reactant can occur through an asynchronous concerted mechanism. A primary...
Monte Carlo simulation of 2-ethoxyethanol in continuum configurational biased procedure: Conformational analysis and association in aqueous and non-aqueous media, Article Theoretical Chemistry Accounts ; Volume 107, Issue 3 , 2002 , Pages 162-172 ; 1432881X (ISSN) ; Jalili, S ; Sharif University of Technology
Springer New York 2002
Monte Carlo simulations have been carried out for 2-ethoxyethanol (C 2E1) in isothermal-isobaric ensemble (NPT) at different temperatures and 1 atm pressure with a continuum configurational biased procedure in water and chloroform media. Hydrogen bond bridges were formed between adjacent oxygen atoms in C2E1 (CH 3CH2OCH2CH2OH) through water molecules. We also found that the stable conformers of C2E 1 in water and CHCl3 are different and the effect of temperature on solute-solvent interaction energies is considerable. The self-association of C2E1 in aqueous and nonaqueous media has been studied by statistical perturbation theory, and the relative free energy has been obtained at different...
Theoretical Study of Solvent and Substituent Effects on Kinetic and Mechanism of Organic Reactions and Theoretical Study of Enzyme Reactions, Ph.D. Dissertation Sharif University of Technology ; Gholami, Mohammad Reza
Computational chemistry is used to study solvent and substituent effects on kinetics and mechanism of some organic reactions. It also is used to study enzyme reactions and enzyme structures. Organic reactions were studied by ab initio quantum mechanics and Monte Carlo simulations. The enzyme studies were done by QM/MM and MD methods in Lund University. The studied organic reactions are 1) Reactions of hydroxylamine and aminoxide anion with methyl iodide. 2) Rearrangement of allyl p-tolyl ether. 3) Reactions of 1,4-Benzoquinone with Cyclopentadiene and Cyclohexadiene derivatives and reaction of cyclopentadiene and vinyl acetate. In the enzyme studies the catalytic reaction of Glyoxalase...
Ph.D. Dissertation Sharif University of Technology ; Vosoughi, Naser
The present ph.D. thesis consists of three sections including the static calculation, neutron noise calculation and neutron noise source unfolding in VVER-1000 reactor core. The multi-group, two dimensional neutron diffusion equations and corresponding adjoint equations are solved in the static calculation. The spatial discretization of equations is based on Galerkin Finite Element Method (GFEM) using unstructured triangle elements generated by Gambit software. The static calculation is performed for both linear and quadratic approximations of shape function; baesd on which results are compared. Using power iteration method for the static calculation, the neutron and adjoint fluxes with the...
Ph.D. Dissertation Sharif University of Technology ; Ghofrani, Mohammad Bagher
This thesis has been done with the goal of comprehensive neutronic calculation of a small size High Temperature Gas Cooled Reactor and HTTR was selected as a reference reactor for simulations. Calculations are divided into four parts of zero and full power stochastic calculations, deterministic calculations and noise analysis. In zero power calculations, an algorithm is proposed for modeling random arrangement of TRISO particles in the fuel compacts of HTTR. The effect of this arrangement on criticality calculations, i.e. effective multiplication factor and critical position of control rods, is then compared with regular arrangement. In the second part, full power calculations with the use...
Article Physica C: Superconductivity and its Applications ; Volume 497 , 15 February , 2014 , 2014, Pages 84-88 ; ISSN: 09214534 ; Rasti, M ; Akhavan, M ; Sharif University of Technology
The details of the crystal structure of the recently discovered Y 3Ba5Cu8O18+δ (Y358) superconductor have been determined by ab initio density functional theory. Total energy calculation has been performed for three different suggested structures with different oxygen content. The structure with a center of inversion symmetry and the highest oxygen concentration has the lowest total energy. Thus, it is the best choice for the Y358 crystal structure. By investigating the detailed structure, it is seen that this compound is arranged either of YBa2Cu3O7 and YBaCu2O 5 or YBaCu2O5 and BaCuO2 substructural blocks in the c direction. The difference between the total energy of Y358 compound and the...
Article Annals of Nuclear Energy ; Vol. 63 , 2014 , pp. 205-208 ; ISSN: 03064549 ; Vosoughi, N ; Sharif University of Technology
To quantify the core barrel motion (CBM) in a pressurized water reactor, a scaling factor can be calculated to convert the Root Mean Square (RMS) value of the ex-core signals (%) to the core barrel motion amplitude (mil) (Thompson et al., 1980). In the current paper, a scaling factor is calculated using the direct and adjoint methods for a typical VVER-1000 reactor. The scaling factor is calculated using the perturbed parameters that result from CBM. The results show that the calculated scaling factors are not the same in one and two-dimensional modeling, and strongly depend on the ex-core detector location. The linearity assumption of relative detector response versus the small displacement...
Article Journal of Chemical Physics ; Volume 137, Issue 19 , 2012 ; 00219606 (ISSN) ; Taherkhani, F ; Parsafar, G ; Caro, A ; Fortunelli, A ; Sharif University of Technology
The energetics and kinetic energy barriers of vacancy/atom exchange in a 37-atom truncated octahedron Ag-Pt binary cluster in the Ag-rich range of compositions are investigated via a first-principles atomistic approach. The energy of the local minima obtained considering various distributions of a single vacancy and a few Pt atoms within the cluster and the energy barriers connecting them are evaluated using accurate density-functional calculations. The effects of the simultaneous presence of a vacancy and Pt atoms are found to be simply additive when their distances are larger than first-neighbors, whereas when they can be stabilizing at low Pt content due to the release of strain by the...
Article Turkish Journal of Electrical Engineering and Computer Sciences ; Volume 23, Issue 1 , 2015 , Pages 52-66 ; 13000632 (ISSN) ; Fotuhi Firuzabad, M ; Aminifar, F ; Sharif University of Technology
The overall system status calculated by pflower flow analysis is the most basic information used for all decisions taken by power system operators and planners. While conventional AC pflower flow solutions are computationally tractable, approximate DC models are employed in many applications, such as optimal power flow studies and unit commitment problems, mainly due to the linear nature of DC models. These models do not provide any information on the reactive power and voltage magnitude quantities and occasionally inaccurate results of the active power values. This paper presents an efficient power flow approach compromising both the con icting aspects of speed and accuracy. The proposed...
Surfactant binary systems: Ab initio calculations, preferential solvation, and investigation of solvatochromic parameters, Article Journal of Chemical and Engineering Data ; Volume 61, Issue 1 , 2016 , Pages 255-263 ; 00219568 (ISSN) ; Salari, H ; Fakhraee, M ; Gholami, M.R ; Sharif University of Technology
American Chemical Society
Solvatochromic UV-vis shifts of three probes 4-nitroaniline, 4-nitroanisol, and Reichardt's dye in binary mixtures of polyethylene glycol p-(1,1,3,3-tetramethylbutyl)-phenyl ether (Triton X-100 or TX-100) with methanol, ethanol, 1-propanol, and water have been investigated at 298 K. Structural and intermolecular interactions of solvatochromic probes were determined in these systems. Solvatochromic parameters, including normalized polarity (ETN), dipolarity-polarizability (π∗), hydrogen-bond donor (α), and hydrogen-bond acceptor (β) abilities, were measured at a wide range of mole fraction (0 ≤ X ≤ 1) with 0.1 increment. Interestingly, a similar behavior of ETN and α is observed in...