The Experts below are selected from a list of 321 Experts worldwide ranked by ideXlab platform
Yiping Tang - One of the best experts on this subject based on the ideXlab platform.
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a study of associating lennard jones chains by a new reference Radial Distribution function
Fluid Phase Equilibria, 2000Co-Authors: Yiping TangAbstract:Abstract A new Radial Distribution function (RDF) for the Lennard–Jones (LJ) fluid is derived around the LJ potential size (σ). The theoretically based RDF is completely analytical and real. Comparisons with computer simulation data at various conditions indicate that the RDF is very accurate at r
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direct calculation of Radial Distribution function for hard sphere chains
Journal of Chemical Physics, 1996Co-Authors: Yiping Tang, Benjamin C Y LuAbstract:The Laplace transform of the average Radial Distribution function of hard‐sphere chains is obtained following the approximation suggested by Chiew [Mol. Phys. 73, 359 (1991)]. The transform expression is of a simple analytical form. The inverse Laplace transform is made analytically. The resulting expression is capable of calculating directly the Radial Distribution function of hard‐sphere chains for any value of r.
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improved expressions for the Radial Distribution function of hard spheres
Journal of Chemical Physics, 1995Co-Authors: Yiping TangAbstract:The solution of the first‐order Ornstein–Zernike equation is applied to improve the Percus–Yevick Radial Distribution function (RDF) of hard spheres, where the direct correlation function is postulated to hold the Yukawa form outside the hard core. Thermodynamic consistency is imposed to determine the parameters in the postulation. Very simple analytical expressions for the Laplace transform of the RDF are obtained for hard spheres and hard sphere mixtures. The resulting RDFs are compared satisfactorily with computer simulation data.
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first order Radial Distribution functions based on the mean spherical approximation for square well lennard jones and kihara fluids
Journal of Chemical Physics, 1994Co-Authors: Yiping TangAbstract:Following the assumption of the mean spherical approximation, analytical expressions of the first‐order Radial Distribution function are obtained for the square‐well, Lennard‐Jones, and Kihara potentials with a hard core through a complex‐plane analysis. The developed expression yields good agreement with the available computer simulation data for the Radial Distribution function of the Lennard‐Jones fluid.
Andrés Santos - One of the best experts on this subject based on the ideXlab platform.
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Radial Distribution function for hard spheres in fractal dimensions a heuristic approximation
Physical Review E, 2016Co-Authors: Andrés Santos, Mariano Lopez De HaroAbstract:: Analytic approximations for the Radial Distribution function, the structure factor, and the equation of state of hard-core fluids in fractal dimension d (1≤d≤3) are developed as heuristic interpolations from the knowledge of the exact and Percus-Yevick results for the hard-rod and hard-sphere fluids, respectively. In order to assess their value, such approximate results are compared with those of recent Monte Carlo simulations and numerical solutions of the Percus-Yevick equation for a fractal dimension [M. Heinen et al., Phys. Rev. Lett. 115, 097801 (2015)PRLTAO0031-900710.1103/PhysRevLett.115.097801], a good agreement being observed.
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density expansion of the Radial Distribution function and approximate integral equations
2016Co-Authors: Andrés SantosAbstract:This chapter deals with the derivation of the coefficients of the Radial Distribution function in its expansion in powers of density. As in Chap. 3, the main steps involving diagrammatic manipulations are justified with simple examples. The classification of diagrams depending on their topology leads to the introduction of the hypernetted-chain and Percus–Yevick approximations, plus other approximate integral equations. The chapter ends with some relations in connection with the internal consistency among different thermodynamic routes in approximate theories.
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on the Radial Distribution function of a hard sphere fluid
Journal of Chemical Physics, 2006Co-Authors: Lopez M De Haro, Andrés Santos, S. Bravo YusteAbstract:Two related approaches, one fairly recent [A. Trokhymchuk et al., J. Chem. Phys.123, 024501 (2005)] and the other one introduced 15years ago [S. B. Yuste and A. Santos, Phys. Rev. A43, 5418 (1991)], for the derivation of analytical forms of the Radial Distribution function of a fluid of hard spheres are compared. While they share similar starting philosophy, the first one involves the determination of 11 parameters while the second is a simple extension of the solution of the Percus-Yevick equation. It is found that the second approach has a better global accuracy and the further asset of counting already with a successful generalization to mixtures of hard spheres and other related systems.
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on the Radial Distribution function of a hard sphere fluid
arXiv: Statistical Mechanics, 2006Co-Authors: Lopez M De Haro, Andrés Santos, S. Bravo YusteAbstract:Two related approaches, one fairly recent [A. Trokhymchuk et al., J. Chem. Phys. 123, 024501 (2005)] and the other one introduced fifteen years ago [S. B. Yuste and A. Santos, Phys. Rev. A 43, 5418 (1991)], for the derivation of analytical forms of the Radial Distribution function of a fluid of hard spheres are compared. While they share similar starting philosophy, the first one involves the determination of eleven parameters while the second is a simple extension of the solution of the Percus-Yevick equation. It is found that the {second} approach has a better global accuracy and the further asset of counting already with a successful generalization to mixtures of hard spheres and other related systems.
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A heuristic Radial Distribution function for hard disks
The Journal of Chemical Physics, 1993Co-Authors: S. Bravo Yuste, Andrés SantosAbstract:We propose a model Radial Distribution function for hard disks that is interpolated between the Percus–Yevick Distribution functions for hard rods and hard spheres. The model contains a mixing parameter and two scaling parameters, which are determined by imposing self‐consistency with an extension to d=2 of the Carnahan–Starling equation of state. Comparison with computer simulation is carried out.
Ruben Romero - One of the best experts on this subject based on the ideXlab platform.
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a mixed integer lp model for the optimal allocation of voltage regulators and capacitors in Radial Distribution systems
International Journal of Electrical Power & Energy Systems, 2013Co-Authors: John F Franco, Marcos J Rider, Marina Lavorato, Ruben RomeroAbstract:Abstract This paper presents a mixed-integer linear programming model to solve the problem of allocating voltage regulators and fixed or switched capacitors (VRCs) in Radial Distribution systems. The use of a mixed-integer linear model guarantees convergence to optimality using existing optimization software. In the proposed model, the steady-state operation of the Radial Distribution system is modeled through linear expressions. The results of one test system and one real Distribution system are presented in order to show the accuracy as well as the efficiency of the proposed solution technique. An heuristic to obtain the Pareto front for the multiobjective VRCs allocation problem is also presented.
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a mixed integer linear programming approach for optimal type size and allocation of distributed generation in Radial Distribution systems
Electric Power Systems Research, 2013Co-Authors: Augusto C Ruedamedina, Marcos J Rider, John F Franco, Antonio Padilhafeltrin, Ruben RomeroAbstract:Abstract This paper presents a mixed-integer linear programming approach to solving the problem of optimal type, size and allocation of distributed generators (DGs) in Radial Distribution systems. In the proposed formulation, (a) the steady-state operation of the Radial Distribution system, considering different load levels, is modeled through linear expressions; (b) different types of DGs are represented by their capability curves; (c) the short-circuit current capacity of the circuits is modeled through linear expressions; and (d) different topologies of the Radial Distribution system are considered. The objective function minimizes the annualized investment and operation costs. The use of a mixed-integer linear formulation guarantees convergence to optimality using existing optimization software. The results of one test system are presented in order to show the accuracy as well as the efficiency of the proposed solution technique.
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optimal conductor size selection and reconductoring in Radial Distribution systems using a mixed integer lp approach
IEEE Transactions on Power Systems, 2013Co-Authors: John F Franco, Marcos J Rider, Marina Lavorato, Ruben RomeroAbstract:This paper presents a mixed-integer linear programming model to solve the conductor size selection and reconductoring problem in Radial Distribution systems. In the proposed model, the steady-state operation of the Radial Distribution system is modeled through linear expressions. The use of a mixed-integer linear model guarantees convergence to optimality using existing optimization software. The proposed model and a heuristic are used to obtain the Pareto front of the conductor size selection and reconductoring problem considering two different objective functions. The results of one test system and two real Distribution systems are presented in order to show the accuracy as well as the efficiency of the proposed solution technique.
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optimal capacitor placement in Radial Distribution networks
IEEE Transactions on Power Systems, 2001Co-Authors: R A Gallego, A Monticelli, Ruben RomeroAbstract:The capacitor placement (replacement) problem for Radial Distribution networks determines capacitor types, sizes, locations, and control schemes. Optimal capacitor placement is a hard combinatorial problem that can be formulated as a mixed integer nonlinear program. Since this is a nonpolynomial time (NP) complete problem, the solution approach uses a combinatorial search algorithm. The paper proposes a hybrid method drawn upon the Tabu search approach, extended with features taken from other combinatorial approaches such as genetic algorithms and simulated annealing, and from practical heuristic approaches. The proposed method has been tested in a range of networks available in the literature with superior results regarding both quality and cost of solutions.
S. Bravo Yuste - One of the best experts on this subject based on the ideXlab platform.
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on the Radial Distribution function of a hard sphere fluid
Journal of Chemical Physics, 2006Co-Authors: Lopez M De Haro, Andrés Santos, S. Bravo YusteAbstract:Two related approaches, one fairly recent [A. Trokhymchuk et al., J. Chem. Phys.123, 024501 (2005)] and the other one introduced 15years ago [S. B. Yuste and A. Santos, Phys. Rev. A43, 5418 (1991)], for the derivation of analytical forms of the Radial Distribution function of a fluid of hard spheres are compared. While they share similar starting philosophy, the first one involves the determination of 11 parameters while the second is a simple extension of the solution of the Percus-Yevick equation. It is found that the second approach has a better global accuracy and the further asset of counting already with a successful generalization to mixtures of hard spheres and other related systems.
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on the Radial Distribution function of a hard sphere fluid
arXiv: Statistical Mechanics, 2006Co-Authors: Lopez M De Haro, Andrés Santos, S. Bravo YusteAbstract:Two related approaches, one fairly recent [A. Trokhymchuk et al., J. Chem. Phys. 123, 024501 (2005)] and the other one introduced fifteen years ago [S. B. Yuste and A. Santos, Phys. Rev. A 43, 5418 (1991)], for the derivation of analytical forms of the Radial Distribution function of a fluid of hard spheres are compared. While they share similar starting philosophy, the first one involves the determination of eleven parameters while the second is a simple extension of the solution of the Percus-Yevick equation. It is found that the {second} approach has a better global accuracy and the further asset of counting already with a successful generalization to mixtures of hard spheres and other related systems.
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A heuristic Radial Distribution function for hard disks
The Journal of Chemical Physics, 1993Co-Authors: S. Bravo Yuste, Andrés SantosAbstract:We propose a model Radial Distribution function for hard disks that is interpolated between the Percus–Yevick Distribution functions for hard rods and hard spheres. The model contains a mixing parameter and two scaling parameters, which are determined by imposing self‐consistency with an extension to d=2 of the Carnahan–Starling equation of state. Comparison with computer simulation is carried out.
Y C Chiew - One of the best experts on this subject based on the ideXlab platform.
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Radial Distribution function of freely jointed hard sphere chains in the solid phase
Journal of Chemical Physics, 2006Co-Authors: T W Cochran, Y C ChiewAbstract:Monte Carlo simulation is used to generate the Radial Distribution function of freely jointed tangent-bonded hard-sphere chains in the disordered solid phase for chain lengths of three, four, six, and eight segments. The data are used to create an accurate analytical expression of the total Radial Distribution function of the hard-sphere chains that covers a density range from the solidification point up to a packing fraction of 0.71. It is envisioned that the correlation will help further progress toward molecular thermodynamic treatment of the solid phase in general and toward perturbed chain theories for the solid phase, in particular.
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analytical integral equation theory for a restricted primitive model of polyelectrolytes and counterions within the mean spherical approximation ii Radial Distribution functions
Journal of Chemical Physics, 2003Co-Authors: N Von Solms, Y C ChiewAbstract:We have solved a polymerizing version of the mean spherical approximation for polyelectrolytes. The polyelectrolytes are modeled as tangentially-bonded hard-sphere segments interacting via the Coulombic potential in a continuous medium with dielectric constant. Analytical solutions for thermodynamic properties and Radial Distribution functions at contact, as well as numerical solutions using a multiple-variable version of the Perram algorithm for Radial Distribution functions at separations beyond the core, are obtained for some specific systems (negatively charged chains of various length and counterions). Comparisons were made with published experimental data for osmotic pressure and with computer simulations for Radial Distribution functions. Good agreement is found for the osmotic pressure at all ranges of density. Good agreement is found for the Radial Distribution functions at moderate to high density.
