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radial-distributions
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Analytic solution to integral equations of liquid state theories for potentials with a hard core at low densities
, Article Journal of the Physical Society of Japan ; Volume 73, Issue 5 , 2004 , Pages 1197-1204 ; 00319015 (ISSN) ; Parsafar, G. A ; Najafi, B ; Sharif University of Technology
Physical Society of Japan
2004
Abstract
We present in this paper a general analytical solution to the integral equations of liquid state theories (Born-Green-Yvon, hyper-netted-chain, and Percus-Yevick Equations) at low-density limit for potentials with a hard core. For the specific case of the Lennard-Jones potential with a hard core, we have derived an analytical function for the radial distribution function at high temperature and low density. We have noted that this function has two humps which is the characteristic feature of the radial distribution function at low densities. In addition, this function has been used to calculate the third virial coefficient for such a fluid exactly. We see that for the especial case of...
A new analytical expression for the free energy of hard-core fluids
, Article Journal of the Physical Society of Japan ; Volume 72, Issue 11 , 2003 , Pages 2747-2753 ; 00319015 (ISSN) ; Parsafar, G ; Sharif University of Technology
2003
Abstract
A new potential function, which can in a simple and reasonable manner represent the molecular interaction of many kinds of hard-core fluids by varying the value of its parameter, is proposed. For prediction of thermodynamic properties of hard-core fluids such as the square-well (SW) and hard core Lennard-Jones (HCLJ), a simple perturbed equation of state (EOS) is derived by using the new potential function along with the Barker-Henderson perturbation theory. This method yields a simple and general analytical expression for each thermodynamic property of such fluids. The most important feature of these expressions is that they have no adjustable parameter and in some regions in which there is...
Extension to mixtures of two robust hard-sphere equations of state satisfying the ordered close-packed limit
, Article Canadian Journal of Chemical Engineering ; Volume 79, Issue 4 , 2001 , Pages 678-686 ; 00084034 (ISSN) ; Vera, J. H ; Sharif University of Technology
2001
Abstract
Two new hard-sphere EOS are proposed and tested using the same attractive potential terms used by the SAFT EOS. Generalized expressions for the pair RDF at contact value, the compressibility factor, and the excess chemical potentials have been derived. Extension to mixtures is tested using three mixing rules for multicomponent hard-sphere fluids. The proposed EOS combined with the Santos et al. and the Barrio-Solana mixing rules reproduced the compressibility factors and the excess chemical potentials more accurately than the Boublik-Mansoori-Carnahan-Starling-Leland (BMCSL) EOS. However the pair RDF at contact value had larger deviations than those obtained with the BMCSL EOS. The...
Investigation of complexation behavior of the dithiocarbamates of N 1 ,N n -dicinnamylalkane-1,n-diamines with metals
, Article Journal of Molecular Structure ; Volume 1180 , 2019 , Pages 188-195 ; 00222860 (ISSN) ; Soleymani Movahed, F ; Fathi, M. B ; Daliri, R ; Saidi, M. R ; Sharif University of Technology
Elsevier B.V
2019
Abstract
Synthesis and characterization of metal dithiocarbamate complexes of N 1 ,N 3 -dicinnamylpropane-1,3-diamine, N 1 ,N 4 -dicinnamylbutane-1,4-diamine and N 1 ,N 6 -dicinnamylhexane-1,6-diamine are reported. The ligands are prepared using cinnamaldehyde and primary diamines to provide the corresponding diimines, followed by reduction with NaBH 4 to afford the corresponding secondary diamines. Diamines react with carbon disulfide in basic medium to furnish the corresponding bis(dithiocarbamate) salts, which underwent complexation with metals. The prepared complexes were characterized by IR, 1 H and 13 C NMR, TGA and elemental analyses. Although the dinuclear metal dithiocarbamate macrocyclic...
Study of self-association of water in supercritical CO2 by Monte Carlo simulation: Does water have a specific interaction with CO2?
, Article Fluid Phase Equilibria ; Volume 267, Issue 2 , 2008 , Pages 181-187 ; 03783812 (ISSN) ; Khanlarkhani, A ; Sharif University of Technology
2008
Abstract
The extent of the self-association of water in supercritical CO2 has been investigated in a wide range of density and temperature by the test particle insertion technique. The results show that the association constant for water decreases with temperature and weakly depends on CO2 density. This weak density dependence provides evidence for the lack of a strong specific CO2-water interaction. Comparing calculated association constants with its gas-phase values shows that the association constant is at most ca. 38% lower than its gas-phase value in the high density-low temperature region. Inspection of the simulated radial distribution functions revealed that forming modest water-CO2 complexes...
Calculation of thermodynamic properties of simple fluids using a new derived pair correlation function
, Article Fluid Phase Equilibria ; Volume 254, Issue 1-2 , 2007 , Pages 138-143 ; 03783812 (ISSN) ; Parsafar, G. A ; Najafi, B ; Sharif University of Technology
2007
Abstract
Based on a new derived radial distribution function (RDF) for potentials with a hard-core we have presented in this paper a method to apply the derived RDF for calculating thermodynamic properties of real fluids up to moderate densities. In order to use the derived RDF for real fluids, one of the potential parameters is chosen in such a way that the RDF behaves more like that for a real fluid. Hence we have been able to calculate all thermodynamic properties of a simple fluid analytically. We have then applied our procedure to a Lennard-Jones fluid and compared the results with simulation data. The agreement is good up to moderate densities, i.e. ρ* ≤ 0.6, which lies in the liquid range of...
Optimal DG placement and sizing based on MICP in radial distribution networks
, Article IEEE Proceedings 2017 Smart Grid Conference, SGC 2017 ; Volume 2018-January , 2018 , Pages 1-6 ; 9781538642795 (ISBN) ; Ranjbar, A. M ; Safdarian, A ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2018
Abstract
Electric distribution system is one of the most important parts of power systems owing to delivering electricity to consumers. The major amount of losses in a power system is in distribution level. Optimal distributed generation (DG) placement and sizing have a significant effect on power loss reduction in distribution systems. In this paper, a mixed integer conic programming (MICP) approach is presented to solve the problem of DG placement, sizing, and hourly generation with the aim of reducing power loss and costs in radial distribution systems. The costs include both investment and operational costs of DGs. Hourly load variations are considered in the model. To verify the effectiveness of...
Investigation of Nucleation and Growth of Metallic Nanoparticlaes from the Gas Phase by Molecular Dynamic Simulation
, M.Sc. Thesis Sharif University of Technology ; Askari, Masoud (Supervisor) ; Simchi, Abdolreza (Supervisor)
Abstract
Formation of nanoparticles by the gas phase condensation process is one of the most promising methods for the nanoparticles synthesis. Finding the correlations between adjustable parameters of the process and nanoparticles properties depends on how parameters affect the mechanism of nucleation and growth. The use of classical nucleation theory at nanoscale leads to unacceptable results; hence, approaches such as molecular dynamic simulation (MD) have been proposed to investigate the mechanism of nucleation and growth at atomic scale. In the present work, the formation of iron clusters from a supersaturated gas phase was investigated via molecular dynamics simulation. For thermalization of...
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
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...
Physically based wall boundary condition for dissipative particle dynamics
, Article Microfluidics and Nanofluidics ; Vol. 17, issue. 1 , July , 2014 , p. 181-198 ; Saidi, M. S ; Sharif University of Technology
Abstract
In this paper, we present a novel wall boundary condition model, which stands just on the physical facts, for the dissipative particle dynamics (DPD) method. After the validation of this model by means of the common benchmarks such as the Couette and the Poiseuille flows, we study the effects of this model on the diffusion coefficient in a wide variety of different coarse-graining levels. The obtained results show that the proposed model preserves the thermodynamics of the system, also eliminates the spurious effects of the wall, and consequently is able to preserve the accurate structural characteristics of the working DPD fluid in the wall's vicinity. We also study the fluid flow through a...
An analytical direct correlation function for hard core double Yukawa potential
, Article Journal of Non-Crystalline Solids ; Volume 356, Issue 43 , 2010 , Pages 2247-2250 ; 00223093 (ISSN) ; Parsafar, G. A ; Hashim, R ; Sharif University of Technology
Abstract
Using a general expression for the second term in the density expansion of the hard core potentials, we obtained an analytical expression for the direct correlation function of the hard core double Yukawa potential. The results of this calculation using the proposed direct correlation function and its related radial distribution function through the Ornstein-Zernike equation show good agreements with those obtained by the computer simulation of the same model
Optimal deployment of remote-controlled switches in distribution networks considering laterals
, Article IET Generation, Transmission and Distribution ; Volume 13, Issue 15 , 2019 , Pages 3264-3271 ; 17518687 (ISSN) ; Farajollahi, M ; Safdarian, A ; Sharif University of Technology
Institution of Engineering and Technology
2019
Abstract
Remote-controlled switch (RCS) placement problem is used to optimally deploy the switches in distribution networks to enhance system reliability. The candidate locations of RCSs are usually assumed at the main feeder while the possible locations on the laterals are ignored. This study studies the impact of considering laterals as potential switch locations and demonstrates that deploying RCSs in laterals would change the optimal number and location of the switches. To do so, this study proposes a mathematical model for the switch deployment problem by taking into account the laterals. The proposed model is formulated in mixed integer linear programming format which can be solved via...
Optimal switch placement in distribution systems using trinary particle swarm optimization algorithm
, Article IEEE Transactions on Power Delivery ; Volume 23, Issue 1 , 2008 , Pages 271-279 ; 08858977 (ISSN) ; Fotuhi Firuzabad, M ; Sharif University of Technology
2008
Abstract
Achieving high-distribution reliability levels and concurrently minimizing capital costs can be considered as the main issues in distribution system optimization. Determination of the optimum number and location of switches in distribution system automation is an important issue from the reliability and economical points of view. In this paper, a novel three-state approach inspired from the discrete version of a powerful heuristic algorithm, particle swarm optimization, is developed and presented to determine the optimum number and locations of two types of switches (sectionalizers and breakers) in radial distribution systems. The novelty of the proposed algorithm is to simultaneously...
Calibration of PTZ Cameras from Multiview Soccer Match Videos
, M.Sc. Thesis Sharif University of Technology ; Kasaei, Shohreh (Supervisor)
Abstract
Camera calibration in sport videos has applications such as sport video analysis, insertion of virtual graphical elements, and 3D reconstruction. Our goal in this research is to fully calibrate cameras in soccer match videos. By calibration parameters, we mean the internal and the external camera parameters. We can have a mapping from world coordinates to image coordinates if we have all the calibration parameters. The cameras used in this research are stationary pan-tilt-zoom cameras. The main challenges in camera calibration are noise, blur, bad lighting conditions, lack of useful information image,fast movement of camera and radial distortion. In addition, as another challenge, we assume...
Mechanical Behavior of Metalic Nano-structures Using a Nonlinear Multi-scale Model Based on Coarse Graining Approach
, M.Sc. Thesis Sharif University of Technology ; Khoei, Amir Reza (Supervisor) ; Jahanshahi, Mohsen (Co-Supervisor)
Abstract
In this thesis ،molecular dynamics simulation of structural and mechanical properties of pure aluminium and copper crystals as well as of the alloyed crystals including 10%,30%,50%,70% and 90% aluminium alloyed have been investigated using two various all-atom and coarse-grained models. Molecular dynamics simulations calculate the realistic behavior of the system and then use them in order to calculate the time average properties of the system. Embedded atom method (eam) and the numerical iterative Boltzmann Inversion method are employed to describe the interaction between atoms. The results are then compared with coarse-grained model. The demonstrated peaks in the radial distribution...
Discussion of "optimal reconfiguration and capacitor allocation in radial distribution systems for energy losses minimization" by L.W. de Oliveira et al., International Journal of Electrical Power and Energy Systems 32 (2010) 840-848
, Article International Journal of Electrical Power and Energy Systems ; Volume 42, Issue 1 , November , 2012 , Pages 701- ; 01420615 (ISSN) ; Vakilian, M ; Sharif University of Technology
2012
Abstract
This article indicates the accurate method for load level calculation to solve the power flow problem when capacitor reactive power is involved. Using the correct method causes some changes in the results and conclusion stated in the discussed paper on optimal reconfiguration and capacitor placement in radial distribution systems
Study of cut-off radius and temperature effects on water molecular behavior using molecular dynamics method
, Article ASME 2011 9th International Conference on Nanochannels, Microchannels, and Minichannels, ICNMM 2011, 19 June 2011 through 22 June 2011, Edmonton, AB ; Volume 2 , 2011 , Pages 277-282 ; 9780791844649 (ISBN) ; Khaledi-Alidusti, R ; Abbaspour, M ; Abbasi, H. R ; Schneider, G ; Sharif University of Technology
2011
Abstract
Water molecules are one of the important molecules in nanofluidics. Its structure and its behavior can change with Temperature and cut-off distance parameters. In this study temperature and cut-off distance effects on the nano-scale water molecules behavior are investigated by molecular dynamics simulations. Many water molecular models have been developed in order to help discover the structure of water molecules. In this study, the flexible three centered (TIP3P-C) water potential is used to model the inter- and intramolecular interactions of the water molecules. In this simulation, we have been studied 512 water molecules with periodic boundary conditions and in a simulation box with 25...
Analytical solution of classic coupled thermoelasticity problem in a rotating disk
, Article Journal of Thermal Stresses ; Volume 38, Issue 11 , Sep , 2015 , Pages 1269-1291 ; 01495739 (ISSN) ; Entezari, A ; Sharif University of Technology
Taylor and Francis Ltd
2015
Abstract
A fully analytical solution of the classic coupled thermoelasticity problem in a rotating disk subjected to thermal and mechanical shock loads is presented. Axisymmetric thermal and mechanical boundary conditions are considered in general forms of arbitrary heat transfer and traction, respectively, at the inner and outer radii of the disk. To solve the governing system of equations, an analytical procedure based on the Fourier-Bessel transform is employed. Closed form formulations are presented for temperature and displacement fields. The results of the present formulations are in good agreement with the numerical results available in the literature. The radial distribution and time history...
Local density variation of gold nanoparticles in aquatic environments
, Article Physica E: Low-Dimensional Systems and Nanostructures ; Volume 84 , 2016 , Pages 489-497 ; 13869477 (ISSN) ; Shirazian, F ; Shahsavari, R ; Khoei, A. R ; Sharif University of Technology
Elsevier
2016
Abstract
Gold (Au) nanoparticles are widely used in diagnosing cancer, imaging, and identification of therapeutic methods due to their particular quantum characteristics. This research presents different types of aqueous models and potentials used in TIP3P, to study the effect of the particle size and density of Au clusters in aquatic environments; so it can be useful to facilitate future investigation of the interaction of proteins with Au nanoparticles. The EAM potential is used to model the structure of gold clusters. It is observed that in the systems with identical gold/water density and different cluster radii, gold particles are distributed in aqueous environment almost identically. Thus, Au...
Topology of polymer chains under nanoscale confinement
, Article Nanoscale ; Volume 9, Issue 33 , 2017 , Pages 12170-12177 ; 20403364 (ISSN) ; Heidari, M ; Mashaghi, S ; Tans, S ; Ejtehadi, M. R ; Mashaghi, A ; Sharif University of Technology
Abstract
Spatial confinement limits the conformational space accessible to biomolecules but the implications for bimolecular topology are not yet known. Folded linear biopolymers can be seen as molecular circuits formed by intramolecular contacts. The pairwise arrangement of intra-chain contacts can be categorized as parallel, series or cross, and has been identified as a topological property. Using molecular dynamics simulations, we determine the contact order distributions and topological circuits of short semi-flexible linear and ring polymer chains with a persistence length of lp under a spherical confinement of radius Rc. At low values of lp/Rc, the entropy of the linear chain leads to the...