Effect of Energy Polydispersity on the Nature of Lennard-Jones Liquids
Ingebrigtsen, Trond S.; Tanaka, Hajime
2016-01-01
In the companion paper [T. S. Ingebrigtsen and H. Tanaka, J. Phys. Chem. B 119, 11052 (2015)] the effect of size polydispersity on the nature of Lennard-Jones (LJ) liquids, which represent most molecular liquids without hydrogen bonds, was studied. More specifically, it was shown that even highly size polydisperse LJ liquids are Roskilde-simple (RS) liquids. RS liquids are liquids with strong correlation between constant volume equilibrium fluctuations of virial and potential energy and are s...
Liquid-vapour phase behaviour of a polydisperse Lennard-Jones fluid
International Nuclear Information System (INIS)
Wilding, Nigel B; Sollich, Peter
2005-01-01
We describe a simulation study of the liquid-vapour phase behaviour of a model polydisperse fluid. Particle interactions are given by a Lennard-Jones potential in which polydispersity features both in the particle sizes and the amplitude of their interactions. We address the computational problem of accurately locating the cloud curve for such a system using Monte Carlo simulations within the grand canonical ensemble. The strongly nonlinear variation of the fractional volumes of the phases across the coexistence region precludes naive extrapolation to determine the cloud point density. Instead we propose an improved estimator for the cloud point location and use scaling arguments to predicts its finite-size behaviour. Excellent agreement is found with the simulation results. Application of the method reveals that the measured cloud curve is highly sensitive to the presence of large particles, even when they are extremely rare. This finding is expected to have implications for the reproducibility of experimentally measured phase diagrams in colloids and polymers
Numerical simulation of pool boiling of a Lennard-Jones liquid
Inaoka, Hajime
2013-09-01
We performed a numerical simulation of pool boiling by a molecular dynamics model. In the simulation, a liquid composed of Lennard-Jones particles in a uniform gravitational field is heated by a heat source at the bottom of the system. The model successfully reproduces the change in regimes of boiling from nucleate boiling to film boiling with the increase of the heat source temperature. We present the pool boiling curve by the model, whose general behavior is consistent with those observed in experiments of pool boiling. © 2013 Elsevier B.V. All rights reserved.
Numerical simulation of pool boiling of a Lennard-Jones liquid
Inaoka, Hajime; Ito, Nobuyasu
2013-01-01
We performed a numerical simulation of pool boiling by a molecular dynamics model. In the simulation, a liquid composed of Lennard-Jones particles in a uniform gravitational field is heated by a heat source at the bottom of the system. The model successfully reproduces the change in regimes of boiling from nucleate boiling to film boiling with the increase of the heat source temperature. We present the pool boiling curve by the model, whose general behavior is consistent with those observed in experiments of pool boiling. © 2013 Elsevier B.V. All rights reserved.
Molecular dynamics studies of the dynamics of supercooled Lennard-Jones liquids
International Nuclear Information System (INIS)
De Leeuw, S.W.; Brakkee, M.J.D.
1990-01-01
Results are presented of molecular dynamics experiments, in which the Lennard-Jones liquid is cooled isobarically into the metastable temperature region below the freezing temperature. The variation of the density-density and transverse current correlation functions with temperature is studied. We observed a power-law behaviour for the temperature dependence of dynamical properties (viscosity and coefficienty of self-diffusion) with an exponent in good agreement with prediction of mode coupling theories and recent experimental results. (author). 23 refs, 5 figs
Phase diagram and universality of the Lennard-Jones gas-liquid system
Watanabe, Hiroshi
2012-01-01
The gas-liquid phase transition of the three-dimensional Lennard-Jones particles system is studied by molecular dynamics simulations. The gas and liquid densities in the coexisting state are determined with high accuracy. The critical point is determined by the block density analysis of the Binder parameter with the aid of the law of rectilinear diameter. From the critical behavior of the gas-liquid coexisting density, the critical exponent of the order parameter is estimated to be β = 0.3285(7). Surface tension is estimated from interface broadening behavior due to capillary waves. From the critical behavior of the surface tension, the critical exponent of the correlation length is estimated to be ν = 0.63(4). The obtained values of β and ν are consistent with those of the Ising universality class. © 2012 American Institute of Physics.
A perturbed Lennard-Jones chain equation of state for liquid metals
Energy Technology Data Exchange (ETDEWEB)
Mousazadeh, M H; Marageh, M Ghanadi [AEOI, JIH Research Laboratory, 11365/8486, Tehran (Iran, Islamic Republic of)
2006-05-24
The perturbed Lennard-Jones chain (PLJC) equation of state is formulated based on first-order variational perturbation theory. The model uses two parameters for a monatomic system, segment size, {sigma}, and segment energy, {epsilon}/k. In this work, we employed the PLJC equation to calculate the liquid density of 26 metals, including alkali and alkali earth metals, iron, cobalt, nickel, copper, silver, gold, zinc, cadmium, mercury, aluminium, gallium, indium, thallium, tin, lead, antimony, and bismuth, for which accurate experimental data exist in the literature. The calculations cover a broad range of temperatures ranging from the melting point to close to the critical point and pressures ranging from the vapour-pressure curve up to pressures as high as 2000 bar. The average absolute deviation in the liquid density predicted by the PLJC equation of state in the saturation line compared with experimental data is 1.26%. Also, using the normal melting temperature and liquid density at melting point (T{sub m}, {rho}{sub m}) as input data for the estimation of the equation of state parameters provides a good correlation of liquid density at saturated and compressed pressures.
Liquid-liquid interfacial properties of a symmetrical Lennard-Jones binary mixture
Energy Technology Data Exchange (ETDEWEB)
Martínez-Ruiz, F. J.; Blas, F. J., E-mail: felipe@uhu.es [Laboratorio de Simulación Molecular y Química Computacional, CIQSO-Centro de Investigación en Química Sostenible and Departamento de Física Aplicada, Universidad de Huelva, 21007 Huelva (Spain); Moreno-Ventas Bravo, A. I. [Laboratorio de Simulación Molecular y Química Computacional, CIQSO-Centro de Investigación en Química Sostenible and Departamento de Geología, Universidad de Huelva, 21007 Huelva (Spain)
2015-09-14
We determine the interfacial properties of a symmetrical binary mixture of equal-sized spherical Lennard-Jones molecules, σ{sub 11} = σ{sub 22}, with the same dispersive energy between like species, ϵ{sub 11} = ϵ{sub 22}, but different dispersive energies between unlike species low enough to induce phase separation. We use the extensions of the improved version of the inhomogeneous long-range corrections of Janecek [J. Phys. Chem. B 110, 6264 (2006)], presented recently by MacDowell and Blas [J. Chem. Phys. 131, 074705 (2009)] and Martínez-Ruiz et al. [J. Chem. Phys. 141, 184701 (2014)], to deal with the interaction energy and microscopic components of the pressure tensor. We perform Monte Carlo simulations in the canonical ensemble to obtain the interfacial properties of the symmetrical mixture with different cut-off distances r{sub c} and in combination with the inhomogeneous long-range corrections. The pressure tensor is obtained using the mechanical (virial) and thermodynamic route. The liquid-liquid interfacial tension is also evaluated using three different procedures, the Irving-Kirkwood method, the difference between the macroscopic components of the pressure tensor, and the test-area methodology. This allows to check the validity of the recent extensions presented to deal with the contributions due to long-range corrections for intermolecular energy and pressure tensor in the case of binary mixtures that exhibit liquid-liquid immiscibility. In addition to the pressure tensor and the surface tension, we also obtain density profiles and coexistence densities and compositions as functions of pressure, at a given temperature. According to our results, the main effect of increasing the cut-off distance r{sub c} is to sharpen the liquid-liquid interface and to increase the width of the biphasic coexistence region. Particularly interesting is the presence of a relative minimum in the total density profiles of the symmetrical mixture. This minimum is related
Liquid-liquid interfacial properties of a symmetrical Lennard-Jones binary mixture
International Nuclear Information System (INIS)
Martínez-Ruiz, F. J.; Blas, F. J.; Moreno-Ventas Bravo, A. I.
2015-01-01
We determine the interfacial properties of a symmetrical binary mixture of equal-sized spherical Lennard-Jones molecules, σ 11 = σ 22 , with the same dispersive energy between like species, ϵ 11 = ϵ 22 , but different dispersive energies between unlike species low enough to induce phase separation. We use the extensions of the improved version of the inhomogeneous long-range corrections of Janecek [J. Phys. Chem. B 110, 6264 (2006)], presented recently by MacDowell and Blas [J. Chem. Phys. 131, 074705 (2009)] and Martínez-Ruiz et al. [J. Chem. Phys. 141, 184701 (2014)], to deal with the interaction energy and microscopic components of the pressure tensor. We perform Monte Carlo simulations in the canonical ensemble to obtain the interfacial properties of the symmetrical mixture with different cut-off distances r c and in combination with the inhomogeneous long-range corrections. The pressure tensor is obtained using the mechanical (virial) and thermodynamic route. The liquid-liquid interfacial tension is also evaluated using three different procedures, the Irving-Kirkwood method, the difference between the macroscopic components of the pressure tensor, and the test-area methodology. This allows to check the validity of the recent extensions presented to deal with the contributions due to long-range corrections for intermolecular energy and pressure tensor in the case of binary mixtures that exhibit liquid-liquid immiscibility. In addition to the pressure tensor and the surface tension, we also obtain density profiles and coexistence densities and compositions as functions of pressure, at a given temperature. According to our results, the main effect of increasing the cut-off distance r c is to sharpen the liquid-liquid interface and to increase the width of the biphasic coexistence region. Particularly interesting is the presence of a relative minimum in the total density profiles of the symmetrical mixture. This minimum is related with a desorption of the
International Nuclear Information System (INIS)
Mulero, A.; Cuadros, F; Faundez, C.A.
1999-01-01
Vapour-liquid equilibrium properties for both three- and two-dimensional Lennard-Jones fluids were obtained using simple cubic-in-density equations of state proposed by the authors. Results were compared with those obtained by other workers from computer simulations and also with results given by other more complex semi-theoretical or semi-empirical equations of state. In the three-dimensional case good agreement is found for all properties and all temperatures. In the two-dimensional case only the coexistence densities were compared, producing good agreement for low temperatures only. The present work is the first to give numerical data for the vapour-liquid equilibrium properties of Lennard-Jones fluids calculated from equations of state. Copyright (1999) CSIRO Australia
Ab initio study of the atomic motion in liquid metal surfaces: comparison with Lennard-Jones systems
International Nuclear Information System (INIS)
Gonzalez, Luis E; Gonzalez, David J
2006-01-01
It is established that liquid metals exhibit surface layering at the liquid-vapour interface, while dielectric simple systems, like those interacting through Lennard-Jones potentials, show a monotonic decay from the liquid density to that of the vapour. First principles molecular dynamics simulations of the free liquid surface of several liquid metals (Li, Na, K, Rb, Cs, Mg, Ba, Al, Tl and Si), and the Na 3 K 7 alloy near their triple points have been performed in order to study the atomic motion at the interface, mainly at the outer layer. Comparison with the results of classical molecular dynamics simulations of a Lennard-Jones system shows interesting differences and similarities. The probability distribution function of the time of residence in a layer shows a peak at very short times and a long-lasting tail. The mean residence time in a layer increases when approaching the interfacial region, slightly in the Lennard-Jones system but strongly in the metallic systems. The motion within the layers, parallel to the interface, can be described as diffusion enhanced (strongly in the case of the outermost layer) with respect to the bulk, for both types of systems, despite its reduced dimensionality in metals
Properties of Organic Liquids when Simulated with Long-Range Lennard-Jones Interactions.
Fischer, Nina M; van Maaren, Paul J; Ditz, Jonas C; Yildirim, Ahmet; van der Spoel, David
2015-07-14
In order to increase the accuracy of classical computer simulations, existing methodologies may need to be adapted. Hitherto, most force fields employ a truncated potential function to model van der Waals interactions, sometimes augmented with an analytical correction. Although such corrections are accurate for homogeneous systems with a long cutoff, they should not be used in inherently inhomogeneous systems such as biomolecular and interface systems. For such cases, a variant of the particle mesh Ewald algorithm (Lennard-Jones PME) was already proposed 20 years ago (Essmann et al. J. Chem. Phys. 1995, 103, 8577-8593), but it was implemented only recently (Wennberg et al. J. Chem. Theory Comput. 2013, 9, 3527-3537) in a major simulation code (GROMACS). The availability of this method allows surface tensions of liquids as well as bulk properties to be established, such as density and enthalpy of vaporization, without approximations due to truncation. Here, we report on simulations of ≈150 liquids (taken from a force field benchmark: Caleman et al. J. Chem. Theory Comput. 2012, 8, 61-74) using three different force fields and compare simulations with and without explicit long-range van der Waals interactions. We find that the density and enthalpy of vaporization increase for most liquids using the generalized Amber force field (GAFF, Wang et al. J. Comput. Chem. 2004, 25, 1157-1174) and the Charmm generalized force field (CGenFF, Vanommeslaeghe et al. J. Comput. Chem. 2010, 31, 671-690) but less so for OPLS/AA (Jorgensen and Tirado-Rives, Proc. Natl. Acad. Sci. U.S.A. 2005, 102, 6665-6670), which was parametrized with an analytical correction to the van der Waals potential. The surface tension increases by ≈10(-2) N/m for all force fields. These results suggest that van der Waals attractions in force fields are too strong, in particular for the GAFF and CGenFF. In addition to the simulation results, we introduce a new version of a web server, http
Hoheisel, C.
1989-01-01
For several liquid states of CF4 and SF4, the shear and the bulk viscosity as well as the thermal conductivity were determined by equilibrium molecular dynamics (MD) calculations. Lennard-Jones four- and six-center pair potentials were applied, and the method of constraints was chosen for the MD. The computed Green-Kubo integrands show a steep time decay, and no particular longtime behavior occurs. The molecule number dependence of the results is found to be small, and 3×105 integration steps allow an accuracy of about 10% for the shear viscosity and the thermal conductivity coefficient. Comparison with experimental data shows a fair agreement for CF4, while for SF6 the transport coefficients fall below the experimental ones by about 30%.
International Nuclear Information System (INIS)
Hoheisel, C.
1989-01-01
For several liquid states of CF 4 and SF 6 , the shear and the bulk viscosity as well as the thermal conductivity were determined by equilibrium molecular dynamics (MD) calculations. Lennard-Jones four- and six-center pair potentials were applied, and the method of constraints were chosen for the MD. The computed Green-Kubo integrands show a steep time decay, and no particular longtime behavior occurs. The molecule number dependence of the results is found to be small, and 3 x 10 5 integration steps allow an accuracy of about 10% for the shear viscosity and the thermal conductivity coefficient. Comparison with experimental data shows a fair agreement for CF 4 , while for SF 6 the transport coefficients fall below the experimental ones by about 30%
International Nuclear Information System (INIS)
Olivi-Tran, N.; Faivre, A.
2009-01-01
We computed a Lennard-Jones frozen liquid with a free surface using classical molecular dynamics. The structure factor curves on the free surface of this sample were calculated for different depths knowing that we have periodic boundary conditions on the other parts of the sample. The resulting structure factor curves show an horizontal shift of their first peak depending on how deep in the sample the curves are computed. We analyze our resulting curves in the light of spatial correlation functions during melting. The conclusion is that the differences between bulk and surface are quite small during melting and that at the end of melting, only the very surface happens to be less dense than the bulk. This result is intrinsic to the shape of the Lennard-Jones potential and does not depend on any other parameter.
International Nuclear Information System (INIS)
Staśkiewicz, B.; Okrasiński, W.
2012-01-01
We propose a simple analytical form of the vapor–liquid equilibrium curve near the critical point for Lennard-Jones fluids. Coexistence densities curves and vapor pressure have been determined using the Van der Waals and Dieterici equation of state. In described method the Bernoulli differential equations, critical exponent theory and some type of Maxwell's criterion have been used. Presented approach has not yet been used to determine analytical form of phase curves as done in this Letter. Lennard-Jones fluids have been considered for analysis. Comparison with experimental data is done. The accuracy of the method is described. -- Highlights: ► We propose a new analytical way to determine the VLE curve. ► Simple, mathematically straightforward form of phase curves is presented. ► Comparison with experimental data is discussed. ► The accuracy of the method has been confirmed.
Scaling relation and regime map of explosive gas–liquid flow of binary Lennard-Jones particle system
Inaoka, Hajime
2012-02-01
We study explosive gasliquid flows caused by rapid depressurization using a molecular dynamics model of Lennard-Jones particle systems. A unique feature of our model is that it consists of two types of particles: liquid particles, which tend to form liquid droplets, and gas particles, which remain supercritical gaseous states under the depressurization realized by simulations. The system has a pipe-like structure similar to the model of a shock tube. We observed physical quantities and flow regimes in systems with various combinations of initial particle number densities and initial temperatures. It is observed that a physical quantity Q, such as pressure, at position z measured along a pipe-like system at time t follows a scaling relation Q(z,t)=Q(zt) with a scaling function Q(ζ). A similar scaling relation holds for time evolution of flow regimes in a system. These scaling relations lead to a regime map of explosive flows in parameter spaces of local physical quantities. The validity of the scaling relations of physical quantities means that physics of equilibrium systems, such as an equation of state, is applicable to explosive flows in our simulations, though the explosive flows involve highly nonequilibrium processes. In other words, if the breaking of the scaling relations is observed, it means that the explosive flows cannot be fully described by physics of equilibrium systems. We show the possibility of breaking of the scaling relations and discuss its implications in the last section. © 2011 Elsevier B.V. All rights reserved.
International Nuclear Information System (INIS)
Costigliola, Lorenzo; Schrøder, Thomas B.; Dyre, Jeppe C.
2016-01-01
The recent theoretical prediction by Maimbourg and Kurchan [e-print http://arxiv.org/abs/1603.05023 (2016)] that for regular pair-potential systems the virial potential-energy correlation coefficient increases towards unity as the dimension d goes to infinity is investigated for the standard 12-6 Lennard-Jones fluid. This is done by computer simulations for d = 2, 3, 4 going from the critical point along the critical isotherm/isochore to higher density/temperature. In both cases the virial potential-energy correlation coefficient increases significantly. For a given density and temperature relative to the critical point, with increasing number of dimension the Lennard-Jones system conforms better to the hidden-scale-invariance property characterized by high virial potential-energy correlations (a property that leads to the existence of isomorphs in the thermodynamic phase diagram, implying that it becomes effectively one-dimensional in regard to structure and dynamics). The present paper also gives the first numerical demonstration of isomorph invariance of structure and dynamics in four dimensions. Our findings emphasize the need for a universally applicable 1/d expansion in liquid-state theory; we conjecture that the systems known to obey hidden scale invariance in three dimensions are those for which the yet-to-be-developed 1/d expansion converges rapidly.
Directory of Open Access Journals (Sweden)
W. Kurniawan
2016-11-01
Full Text Available Penyelesaian persamaan Schrödinger dengan berbagai model potensial sangat penting dilakukan untuk memberikan gambaran perilaku zarah di bawah pengaruh potensial tersebut. Solusinya berupa fungsi gelombang yang memuat informasi penting tentang perilaku gelombang yang ditunjukkan dengan energi terikatnya. Pada penelitian ini kasus yang ingin diteliti adalah model potensial Lennard-Jones dengan menggunakan metode analisa goal seek yang tersedia pada Microsoft excel. Persamaannya dijabarkan dengan metode Euler terlebih dahulu selanjutnya syarat batas ditentukan agar ketelitian hasil diperoleh. Agar perhitungan goal seek dapat dilakukan maka harus diubah dari besaran fisis menjadi besaran yang tidak berdimensi dimana parameter v menunjukkan keklasikan suatu sistem dan nilai ε menunjukkan kuantisasi energi. Hasil yang diperoleh adalah bahwa dengan memasukkan parameter kontrol nilai v tertentu, telah diperoleh beberapa keadaan energi dengan batas zkiri dan zkanan tertentu. Ketika masukan parameter v yang diberikan semakin besar keadaan energinya pun lebih rapat (ditunjukkan energy state yang diperoleh semakin banyak dibandingkan bila masukan v-nya lebih kecil. Penelitian ini bermanfaat untuk menyederhanakan kasus potensial yang lebih rumit, dimana solusinya dapat diperoleh dengan mudah dan konsep kuantisasi energi akibat model potensial L-J dapat dipahami secara utuh. Solution of the Schrödinger equation in various potential model is very important in order to provide an overview of behaviour’s particle under influence of potential model. The solution is a wave function that contains important information are shown by energy state. In this research, the investigated is Lennard Jones potential by using Goal Seek analysis which are available in Microsoft Excel. The equation is described by the Euler method and then boundary condition is determined to perecision result which are obtained. It must be changed in terms dimensionless where
Scaling of the dynamics of flexible Lennard-Jones chains
DEFF Research Database (Denmark)
Veldhorst, Arno; Dyre, Jeppe C.; Schrøder, Thomas
2015-01-01
The previous paper [A. A. Veldhorst et al., J. Chem. Phys. 141, 054904 (2014)] demonstrated that the isomorph theory explains the scaling properties of a liquid of flexible chains consisting of ten Lennard-Jones particles connected by rigid bonds. We here investigate the same model with harmonic......, dynamics, and the excess entropy are invariant. The Lennard-Jones chain liquid with harmonic bondsdoes have curves in the phase diagram along which the structure and dynamics are invariant. The excess entropy is not invariant on these curves, which we refer to as “pseudoisomorphs.” In particular......, this means that Rosenfeld’s excess-entropy scaling (the dynamics being a function of excess entropy only) does not apply for the Lennard-Jones chain with harmonic bonds...
Scaling relation and regime map of explosive gas–liquid flow of binary Lennard-Jones particle system
Inaoka, Hajime; Yukawa, Satoshi; Ito, Nobuyasu
2012-01-01
liquid droplets, and gas particles, which remain supercritical gaseous states under the depressurization realized by simulations. The system has a pipe-like structure similar to the model of a shock tube. We observed physical quantities and flow regimes
Energy Technology Data Exchange (ETDEWEB)
Martínez-Ruiz, F. J.; Blas, F. J., E-mail: felipe@uhu.es [Departamento de Física Aplicada, Universidad de Huelva, 21071 Huelva (Spain); Centro de Investigación de Física Teórica y Matemática, Universidad de Huelva, 21071 Huelva (Spain); Mendiboure, B. [Laboratoire des Fluides Complexes et leurs Réservoirs, UMR5150, Université de Pau et des Pays de l’Adour, B. P. 1155, Pau Cedex 64014 (France); Moreno-Ventas Bravo, A. I. [Centro de Investigación de Física Teórica y Matemática, Universidad de Huelva, 21071 Huelva (Spain); Departamento de Geología, Facultad de Ciencias Experimentales, Universidad de Huelva, 21071 Huelva (Spain)
2014-11-14
We propose an extension of the improved version of the inhomogeneous long-range corrections of Janeček [J. Phys. Chem. B 110, 6264–6269 (2006)], presented recently by MacDowell and Blas [J. Chem. Phys. 131, 074705 (2009)] to account for the intermolecular potential energy of spherical, rigid, and flexible molecular systems, to deal with the contributions to the microscopic components of the pressure tensor due to the dispersive long-range corrections. We have performed Monte Carlo simulations in the canonical ensemble to obtain the interfacial properties of spherical Lennard-Jones molecules with different cutoff distances, r{sub c} = 2.5, 3, 4, and 5σ. In addition, we have also considered cutoff distances r{sub c} = 2.5 and 3σ in combination with the inhomogeneous long-range corrections proposed in this work. The normal and tangential microscopic components of the pressure tensor are obtained using the mechanical or virial route in combination with the recipe of Irving and Kirkwood, while the macroscopic components are calculated using the Volume Perturbation thermodynamic route proposed by de Miguel and Jackson [J. Chem. Phys. 125, 164109 (2006)]. The vapour-liquid interfacial tension is evaluated using three different procedures, the Irving-Kirkwood method, the difference between the macroscopic components of the pressure tensor, and the Test-Area methodology. In addition to the pressure tensor and the surface tension, we also obtain density profiles, coexistence densities, vapour pressure, critical temperature and density, and interfacial thickness as functions of temperature, paying particular attention to the effect of the cutoff distance and the long-range corrections on these properties. According to our results, the main effect of increasing the cutoff distance (at fixed temperature) is to sharpen the vapour-liquid interface, to decrease the vapour pressure, and to increase the width of the biphasic coexistence region. As a result, the interfacial
International Nuclear Information System (INIS)
Martínez-Ruiz, F. J.; Blas, F. J.; Mendiboure, B.; Moreno-Ventas Bravo, A. I.
2014-01-01
We propose an extension of the improved version of the inhomogeneous long-range corrections of Janeček [J. Phys. Chem. B 110, 6264–6269 (2006)], presented recently by MacDowell and Blas [J. Chem. Phys. 131, 074705 (2009)] to account for the intermolecular potential energy of spherical, rigid, and flexible molecular systems, to deal with the contributions to the microscopic components of the pressure tensor due to the dispersive long-range corrections. We have performed Monte Carlo simulations in the canonical ensemble to obtain the interfacial properties of spherical Lennard-Jones molecules with different cutoff distances, r c = 2.5, 3, 4, and 5σ. In addition, we have also considered cutoff distances r c = 2.5 and 3σ in combination with the inhomogeneous long-range corrections proposed in this work. The normal and tangential microscopic components of the pressure tensor are obtained using the mechanical or virial route in combination with the recipe of Irving and Kirkwood, while the macroscopic components are calculated using the Volume Perturbation thermodynamic route proposed by de Miguel and Jackson [J. Chem. Phys. 125, 164109 (2006)]. The vapour-liquid interfacial tension is evaluated using three different procedures, the Irving-Kirkwood method, the difference between the macroscopic components of the pressure tensor, and the Test-Area methodology. In addition to the pressure tensor and the surface tension, we also obtain density profiles, coexistence densities, vapour pressure, critical temperature and density, and interfacial thickness as functions of temperature, paying particular attention to the effect of the cutoff distance and the long-range corrections on these properties. According to our results, the main effect of increasing the cutoff distance (at fixed temperature) is to sharpen the vapour-liquid interface, to decrease the vapour pressure, and to increase the width of the biphasic coexistence region. As a result, the interfacial thickness
Evaporation of Lennard-Jones fluids.
Cheng, Shengfeng; Lechman, Jeremy B; Plimpton, Steven J; Grest, Gary S
2011-06-14
Evaporation and condensation at a liquid/vapor interface are ubiquitous interphase mass and energy transfer phenomena that are still not well understood. We have carried out large scale molecular dynamics simulations of Lennard-Jones (LJ) fluids composed of monomers, dimers, or trimers to investigate these processes with molecular detail. For LJ monomers in contact with a vacuum, the evaporation rate is found to be very high with significant evaporative cooling and an accompanying density gradient in the liquid domain near the liquid/vapor interface. Increasing the chain length to just dimers significantly reduces the evaporation rate. We confirm that mechanical equilibrium plays a key role in determining the evaporation rate and the density and temperature profiles across the liquid/vapor interface. The velocity distributions of evaporated molecules and the evaporation and condensation coefficients are measured and compared to the predictions of an existing model based on kinetic theory of gases. Our results indicate that for both monatomic and polyatomic molecules, the evaporation and condensation coefficients are equal when systems are not far from equilibrium and smaller than one, and decrease with increasing temperature. For the same reduced temperature T/T(c), where T(c) is the critical temperature, these two coefficients are higher for LJ dimers and trimers than for monomers, in contrast to the traditional viewpoint that they are close to unity for monatomic molecules and decrease for polyatomic molecules. Furthermore, data for the two coefficients collapse onto a master curve when plotted against a translational length ratio between the liquid and vapor phase.
Melting of 2D monatomic solids: Lennard-Jones system
International Nuclear Information System (INIS)
Yi, Y.M.; Guo, Z.C.
1987-09-01
The Lennard-Jones interaction has been introduced into the Collins mix lattice of 2D liquids. By means of rigorous calculation of the total potential and the free area, the Gibbs functions for 2D liquid and solid have been derived. The melting line obtained from the phase transition equation agrees quite well with the result of recent computer simulation experiments. The obtained reduced temperature of the triple point T* t =0.438 agrees with the data measured in experiments of some inert gas monolayers adsorbed on graphite as well as in computer simulation experiments. (author). 11 refs, 7 figs, 3 tabs
Thermal decay of Lennard-Jones clusters
International Nuclear Information System (INIS)
Garzon, I.L.; Avalos-Borja, M.
1989-01-01
The decay mechanisms of argon clusters have been studied using molecular dynamics simulations and Lennard-Jones potentials. Heating up processes were applied to Ar 13 up to temperatures in the melting region. In this range of temperatures large fluctuations in the mean kinetic energy of the system are present and a sequential evaporation is observed. The thermal decay of these aggregates occurs in a time scale of nanoseconds. (orig.)
Evaporation of Lennard-Jones clusters
International Nuclear Information System (INIS)
Roman, C.E.; Garzon, I.L.
1991-01-01
Extensive molecular dynamics simulations have been done to study the evaporation of a 13-atom Lennard-Jones cluster. The survival probability and the evaporative lifetime are calculated as a function of the cluster total energy from a classical trajectory analysis. The results are interpreted in terms of the RRK theory of unimolecular dissociation. The calculation of the binding energy of the evaporated species from the evaporation rate and the average kinetic energy release is discussed. (orig.)
Phase diagram of power law and Lennard-Jones systems: Crystal phases
International Nuclear Information System (INIS)
Travesset, Alex
2014-01-01
An extensive characterization of the low temperature phase diagram of particles interacting with power law or Lennard-Jones potentials is provided from Lattice Dynamical Theory. For power law systems, only two lattice structures are stable for certain values of the exponent (or softness) (A15, body centered cube (bcc)) and two more (face centered cubic (fcc), hexagonal close packed (hcp)) are always stable. Among them, only the fcc and bcc are equilibrium states. For Lennard-Jones systems, the equilibrium states are either hcp or fcc, with a coexistence curve in pressure and temperature that shows reentrant behavior. The hcp solid never coexists with the liquid. In all cases analyzed, for both power law and Lennard-Jones potentials, the fcc crystal has higher entropy than the hcp. The role of anharmonic terms is thoroughly analyzed and a general thermodynamic integration to account for them is proposed
Theoretical prediction of crystallization kinetics of a supercooled Lennard-Jones fluid
Gunawardana, K. G. S. H.; Song, Xueyu
2018-05-01
The first order curvature correction to the crystal-liquid interfacial free energy is calculated using a theoretical model based on the interfacial excess thermodynamic properties. The correction parameter (δ), which is analogous to the Tolman length at a liquid-vapor interface, is found to be 0.48 ± 0.05 for a Lennard-Jones (LJ) fluid. We show that this curvature correction is crucial in predicting the nucleation barrier when the size of the crystal nucleus is small. The thermodynamic driving force (Δμ) corresponding to available simulated nucleation conditions is also calculated by combining the simulated data with a classical density functional theory. In this paper, we show that the classical nucleation theory is capable of predicting the nucleation barrier with excellent agreement to the simulated results when the curvature correction to the interfacial free energy is accounted for.
Freezing of Lennard-Jones-type fluids
International Nuclear Information System (INIS)
Khrapak, Sergey A.; Chaudhuri, Manis; Morfill, Gregor E.
2011-01-01
We put forward an approximate method to locate the fluid-solid (freezing) phase transition in systems of classical particles interacting via a wide range of Lennard-Jones-type potentials. This method is based on the constancy of the properly normalized second derivative of the interaction potential (freezing indicator) along the freezing curve. As demonstrated recently it yields remarkably good agreement with previous numerical simulation studies of the conventional 12-6 Lennard-Jones (LJ) fluid [S.A.Khrapak, M.Chaudhuri, G.E.Morfill, Phys. Rev. B 134, 052101 (2010)]. In this paper, we test this approach using a wide range of the LJ-type potentials, including LJ n-6 and exp-6 models, and find that it remains sufficiently accurate and reliable in reproducing the corresponding freezing curves, down to the triple-point temperatures. One of the possible application of the method--estimation of the freezing conditions in complex (dusty) plasmas with ''tunable'' interactions--is briefly discussed.
Phase diagram of a modified Lennard-Jones system
International Nuclear Information System (INIS)
Sakagami, Takahiro; Fuchizaki, Kazuhiro
2010-01-01
The well-known Lennard-Jones potential is modified in such a way that it smoothly vanishes at a certain distance. A system whose interparticle interaction is given by such a potential is referred to as a modified Lennard-Jones system, and is served as a standard system describing simple solids and fluids. A phase diagram is determined based on the free energies obtained through thermodynamic integration.
Melting in Two-Dimensional Lennard-Jones Systems: Observation of a Metastable Hexatic Phase
International Nuclear Information System (INIS)
Chen, K.; Kaplan, T.; Mostoller, M.
1995-01-01
Large scale molecular dynamics simulations of two-dimensional melting have been carried out using a recently revised Parrinello-Rahman scheme on massively parallel supercomputers. A metastable state is observed between the solid and liquid phases in Lennard-Jones systems of 36 864 and 102 400 atoms. This intermediate state shows the characteristics of the hexatic phase predicted by the theory of Kosterlitz, Thouless, Halperin, Nelson, and Young
Cluster fusion algorithm: application to Lennard-Jones clusters
DEFF Research Database (Denmark)
Solov'yov, Ilia; Solov'yov, Andrey V.; Greiner, Walter
2006-01-01
paths up to the cluster size of 150 atoms. We demonstrate that in this way all known global minima structures of the Lennard-Jones clusters can be found. Our method provides an efficient tool for the calculation and analysis of atomic cluster structure. With its use we justify the magic number sequence......We present a new general theoretical framework for modelling the cluster structure and apply it to description of the Lennard-Jones clusters. Starting from the initial tetrahedral cluster configuration, adding new atoms to the system and absorbing its energy at each step, we find cluster growing...... for the clusters of noble gas atoms and compare it with experimental observations. We report the striking correspondence of the peaks in the dependence of the second derivative of the binding energy per atom on cluster size calculated for the chain of the Lennard-Jones clusters based on the icosahedral symmetry...
Cluster fusion algorithm: application to Lennard-Jones clusters
DEFF Research Database (Denmark)
Solov'yov, Ilia; Solov'yov, Andrey V.; Greiner, Walter
2008-01-01
paths up to the cluster size of 150 atoms. We demonstrate that in this way all known global minima structures of the Lennard-Jones clusters can be found. Our method provides an efficient tool for the calculation and analysis of atomic cluster structure. With its use we justify the magic number sequence......We present a new general theoretical framework for modelling the cluster structure and apply it to description of the Lennard-Jones clusters. Starting from the initial tetrahedral cluster configuration, adding new atoms to the system and absorbing its energy at each step, we find cluster growing...... for the clusters of noble gas atoms and compare it with experimental observations. We report the striking correspondence of the peaks in the dependence of the second derivative of the binding energy per atom on cluster size calculated for the chain of the Lennard-Jones clusters based on the icosahedral symmetry...
Contact angle of sessile drops in Lennard-Jones systems.
Becker, Stefan; Urbassek, Herbert M; Horsch, Martin; Hasse, Hans
2014-11-18
Molecular dynamics simulations are used for studying the contact angle of nanoscale sessile drops on a planar solid wall in a system interacting via the truncated and shifted Lennard-Jones potential. The entire range between total wetting and dewetting is investigated by varying the solid-fluid dispersive interaction energy. The temperature is varied between the triple point and the critical temperature. A correlation is obtained for the contact angle in dependence of the temperature and the dispersive interaction energy. Size effects are studied by varying the number of fluid particles at otherwise constant conditions, using up to 150,000 particles. For particle numbers below 10,000, a decrease of the contact angle is found. This is attributed to a dependence of the solid-liquid surface tension on the droplet size. A convergence to a constant contact angle is observed for larger system sizes. The influence of the wall model is studied by varying the density of the wall. The effective solid-fluid dispersive interaction energy at a contact angle of θ = 90° is found to be independent of temperature and to decrease linearly with the solid density. A correlation is developed that describes the contact angle as a function of the dispersive interaction, the temperature, and the solid density. The density profile of the sessile drop and the surrounding vapor phase is described by a correlation combining a sigmoidal function and an oscillation term.
Free energy of the Lennard-Jones solid
Hoef, van der M.A.
2000-01-01
We have determined a simple expression for the absolute Helmholtz free energy of the fcc Lennard-Jones solid from molecular dynamics simulations. The pressure and energy data from these simulations have been fitted to a simple functional form (18 parameters) for densities ranging from around
Scaling of the dynamics of flexible Lennard-Jones chains
DEFF Research Database (Denmark)
Veldhorst, Arno; Dyre, J. C.; Schrøder, Thomas
2014-01-01
functions of excess entropy) which has been observed in simulations of both molecular and polymeric systems. Doing molecular dynamics simulations of flexible Lennard-Jones chains (LJC) with rigid bonds, we here provide the first detailed test of the isomorph theory applied to flexible chain molecules. We...
Thermal conductivity of the Lennard-Jones chain fluid model.
Galliero, Guillaume; Boned, Christian
2009-12-01
Nonequilibrium molecular dynamics simulations have been performed to estimate, analyze, and correlate the thermal conductivity of a fluid composed of short Lennard-Jones chains (up to 16 segments) over a large range of thermodynamic conditions. It is shown that the dilute gas contribution to the thermal conductivity decreases when the chain length increases for a given temperature. In dense states, simulation results indicate that the residual thermal conductivity of the monomer increases strongly with density, but is weakly dependent on the temperature. Compared to the monomer value, it has been noted that the residual thermal conductivity of the chain was slightly decreasing with its length. Using these results, an empirical relation, including a contribution due to the critical enhancement, is proposed to provide an accurate estimation of the thermal conductivity of the Lennard-Jones chain fluid model (up to 16 segments) over the domain 0.8values of the Lennard-Jones chain fluid model merge on the same "universal" curve when plotted as a function of the excess entropy. Furthermore, it is shown that the reduced configurational thermal conductivity of the Lennard-Jones chain fluid model is approximately proportional to the reduced excess entropy for all fluid states and all chain lengths.
Equilibrium spherically curved two-dimensional Lennard-Jones systems
Voogd, J.M.; Sloot, P.M.A.; van Dantzig, R.
2005-01-01
To learn about basic aspects of nano-scale spherical molecular shells during their formation, spherically curved two-dimensional N-particle Lennard-Jones systems are simulated, studying curvature evolution paths at zero-temperature. For many N-values (N < 800) equilibrium configu- rations are traced
Cell-model prediction of the melting of a Lennard-Jones solid
International Nuclear Information System (INIS)
Holian, B.L.
1980-01-01
The classical free energy of the Lennard-Jones 6-12 solid is computed from a single-particle anharmonic cell model with a correction to the entropy given by the classical correlational entropy of quasiharmonic lattice dynamics. The free energy of the fluid is obtained from the Hansen-Ree analytic fit to Monte Carlo equation-of-state calculations. The resulting predictions of the solid-fluid coexistence curves by this corrected cell model of the solid are in excellent agreement with the computer experiments
Phase diagram of a Lennard-Jones solid
International Nuclear Information System (INIS)
Choi, Y.; Ree, T.; Ree, F.H.
1993-01-01
A phase diagram of a Lennard-Jones solid at kT/ε≥0.8 is constructed by our recent perturbation theory. It shows the stability of the face-centered-cubic phase except within a small pressure and temperature domain, where the hexagonal-close packed phase may occur. The theory predicts anharmonic contributions to the Helmholtz free energy (important to the crystal stability) in good agreement with Monte Carlo data
The potential energy landscape in the Lennard-Jones binary mixture model
International Nuclear Information System (INIS)
Sampoli, M; Benassi, P; Eramo, R; Angelani, L; Ruocco, G
2003-01-01
The potential energy landscape in the Kob-Andersen Lennard-Jones binary mixture model has been studied carefully from the liquid down to the supercooled regime, from T = 2 down to 0.46. One thousand independent configurations along the time evolution locus have been examined at each temperature investigated. From the starting configuration, we searched for the nearest saddle (or quasi-saddle) and minimum of the potential energy. The vibrational densities of states for the starting and the two derived configurations have been evaluated. Besides the number of negative eigenvalues of the saddles other quantities show some signature of the approach of the dynamical arrest temperature
Hoheisel, C.
1988-09-01
Equilibrium molecular dynamics calculations with constraints have been performed for model liquids SF6 and CF4. The computations were carried out with four- and six-center Lennard-Jones potentials and up to 2×105 integration steps. Shear, bulk viscosity and the thermal conductivity have been calculated with use of Green-Kubo relations in the formulation of ``molecule variables.'' Various thermodynamic states were investigated. For SF6, a detailed comparison with experimental data was possible. For CF4, the MD results could only be compared with experiment for one liquid state. For the latter liquid, a complementary comparison was performed using MD results obtained with a one-center Lennard-Jones potential. A limited test of the particle number dependence of the results is presented. Partial and total correlations functions are shown and discussed with respect to findings obtained for the one-center Lennard-Jones liquid.
Energy Technology Data Exchange (ETDEWEB)
Barbante, Paolo [Dipartimento di Matematica, Politecnico di Milano - Piazza Leonardo da Vinci 32 - 20133 Milano (Italy); Frezzotti, Aldo; Gibelli, Livio [Dipartimento di Scienze e Tecnologie Aerospaziali, Politecnico di Milano - Via La Masa 34 - 20156 Milano (Italy)
2014-12-09
The unsteady evaporation of a thin planar liquid film is studied by molecular dynamics simulations of Lennard-Jones fluid. The obtained results are compared with the predictions of a diffuse interface model in which capillary Korteweg contributions are added to hydrodynamic equations, in order to obtain a unified description of the liquid bulk, liquid-vapor interface and vapor region. Particular care has been taken in constructing a diffuse interface model matching the thermodynamic and transport properties of the Lennard-Jones fluid. The comparison of diffuse interface model and molecular dynamics results shows that, although good agreement is obtained in equilibrium conditions, remarkable deviations of diffuse interface model predictions from the reference molecular dynamics results are observed in the simulation of liquid film evaporation. It is also observed that molecular dynamics results are in good agreement with preliminary results obtained from a composite model which describes the liquid film by a standard hydrodynamic model and the vapor by the Boltzmann equation. The two mathematical model models are connected by kinetic boundary conditions assuming unit evaporation coefficient.
Phase Diagram of Kob-Andersen-Type Binary Lennard-Jones Mixtures
Pedersen, Ulf R.; Schrøder, Thomas B.; Dyre, Jeppe C.
2018-04-01
The binary Kob-Andersen (KA) Lennard-Jones mixture is the standard model for computational studies of viscous liquids and the glass transition. For very long simulations, the viscous KA system crystallizes, however, by phase separating into a pure A particle phase forming a fcc crystal. We present the thermodynamic phase diagram for KA-type mixtures consisting of up to 50% small (B ) particles showing, in particular, that the melting temperature of the standard KA system at liquid density 1.2 is 1.028(3) in A particle Lennard-Jones units. At large B particle concentrations, the system crystallizes into the CsCl crystal structure. The eutectic corresponding to the fcc and CsCl structures is cutoff in a narrow interval of B particle concentrations around 26% at which the bipyramidal orthorhombic PuBr3 structure is the thermodynamically stable phase. The melting temperature's variation with B particle concentration at two constant pressures, as well as at the constant density 1.2, is estimated from simulations at pressure 10.19 using isomorph theory. Our data demonstrate approximate identity between the melting temperature and the onset temperature below which viscous dynamics appears. Finally, the nature of the solid-liquid interface is briefly discussed.
Glass transitions in one-, two-, three-, and four-dimensional binary Lennard-Jones systems
Energy Technology Data Exchange (ETDEWEB)
Bruening, Ralf; St-Onge, Denis A; Patterson, Steve [Physics Department, Mount Allison University, Sackville, NB, E4L 1E6 (Canada); Kob, Walter [Laboratoire des Colloides, Verres et Nanomateriaux, UMR5587, Universite Montpellier II and CNRS, 34095 Montpellier Cedex (France)], E-mail: rbruening@mta.ca
2009-01-21
We investigate the calorimetric liquid-glass transition by performing simulations of a binary Lennard-Jones mixture in one through four dimensions. Starting at a high temperature, the systems are cooled to T = 0 and heated back to the ergodic liquid state at constant rates. Glass transitions are observed in two, three and four dimensions as a hysteresis between the cooling and heating curves. This hysteresis appears in the energy and pressure diagrams, and the scanning rate dependence of the area and height of the hysteresis can be described using power laws. The one-dimensional system does not experience a glass transition but its specific heat curve resembles the shape of the D{>=}2 results in the supercooled liquid regime above the glass transition. As D increases, the radial distribution functions reflect reduced geometric constraints. Nearest neighbor distances become smaller with increasing D due to interactions between nearest and next-nearest neighbors. Simulation data for the glasses are compared with crystal and melting data obtained with a Lennard-Jones system with only one type of particle and we find that with increasing D crystallization becomes increasingly more difficult.
International Nuclear Information System (INIS)
Vorob'ev, V.S.
2003-01-01
We suggest a concept of multiple disordering scaling of the crystalline state. Such a scaling procedure applied to a crystal leads to the liquid and (in low density limit) gas states. This approach provides an explanation to a high value of configuration (common) entropy of liquefied noble gases, which can be deduced from experimental data. We use the generalized nearest-neighbor approach to calculate free energy and pressure of the Lennard-Jones systems after performing this scaling procedure. These thermodynamic functions depend on one parameter characterizing the disordering only. Condensed states of the system (liquid and solid) correspond to small values of this parameter. When this parameter tends to unity, we get an asymptotically exact equation of state for a gas involving the second virial coefficient. A reasonable choice of the values for the disordering parameter (ranging between zero and unity) allows us to find the lines of coexistence between different phase states in the Lennard-Jones systems, which are in a good agreement with the available experimental data
Icosahedral binary clusters of glass-forming Lennard-Jones binary alloy
International Nuclear Information System (INIS)
Iwamatsu, Masao
2007-01-01
It is widely believed that the local icosahedral structure is related to the formation of bulk metallic glasses (BMGs). Specifically the existence of 13-atom icosahedral cluster in undercooled liquid is imagined to play a key role to initiate the glass formation as the seed of amorphous structure or to block the nucleation of regular crystal as the impurity. The existence of 13-atom icosahedral clusters in one-component liquids was predicted more than half a century ago by Frank from his total energy calculation for isolated clusters. In BMG alloys, however, the situation is less clear. In this report, we present the lowest-energy structures of 13-atom Lennard-Jones binary cluster calculated from the modified space-fixed genetic algorithm. We study, in particular, the artificial Lennard-Jones potential designed by Kob and Andersen [W. Kob, H.C. Andersen, Phys. Rev. E 51 (1995) 4626] that is known to form BMG. Curiously, the lowest-energy structures of 13-atom cluster are non-icosahedral for almost all compositions. Our result suggests that the existence of the icosahedral cluster is not a necessary condition but only a sufficient condition for glass formation
Radiation damage in an amorphous Lennard-Jones solid
International Nuclear Information System (INIS)
Chaki, T.K.; Li, J.C.M.
1985-01-01
A molecular-dynamics simulation of radiation damage in an amorphous Lennard-Jones solid has been undertaken. A three-dimensional structure of 685 atoms with periodic boundary conditions was used. An atom was injected inward from the middle of one surface, and as it lost its energy its velocity and position were recorded. The temperature profile around the injection direction was also calculated. The amorphous structure was examined before and after irradiation by calculating the volume distribution of the Voronoi polyhedra and its time evolution. The production of vacancies and interstitials was observed. The interstitials were found to disappear rapidly, and the vacancies slowly. (author)
A Lennard-Jones-like perspective on first order transitions in biological helices
DEFF Research Database (Denmark)
Oskolkov, Nikolay N.; Bohr, Jakob
2013-01-01
Helical structures with Lennard-Jones self-interactions are studied for optimal conformations. For this purpose, their self-energy is analyzed for extrema with respect to the geometric parameters of the helices. It is found that Lennard-Jones helices exhibit a first order phase transition from...
Freezing and melting line invariants of the Lennard-Jones system
DEFF Research Database (Denmark)
Costigliola, Lorenzo; Schrøder, Thomas; Dyre, Jeppe C.
2016-01-01
The invariance of several structural and dynamical properties of the Lennard-Jones (LJ) system along the freezing and melting lines is interpreted in terms of isomorph theory. First the freezing/melting lines of the LJ system are shown to be approximated by isomorphs. Then we show...... that the invariants observed along the freezing and melting isomorphs are also observed on other isomorphs in the liquid and crystalline phases. The structure is probed by the radial distribution function and the structure factor and dynamics are probed by the mean-square displacement, the intermediate scattering...... function, and the shear viscosity. Studying these properties with reference to isomorph theory explains why the known single-phase melting criteria hold, e.g., the Hansen–Verlet and the Lindemann criteria, and why the Andrade equation for the viscosity at freezing applies, e.g., for most liquid metals. Our...
Glass of monatomic Lennard-Jones system at nanoscale
International Nuclear Information System (INIS)
Vo Van Hoang
2010-01-01
Structure and stability of glass of monatomic Lennard-Jones (LJ) system at nanoscale compared with those of the bulk counterparts have been studied using the classical molecular dynamics (MD) method. Models have been obtained by cooling from the melts. Structure of the systems was analyzed via radial distribution function (RDF), interatomic distances, the Honeycutt-Andersen analysis and coordination number distributions. Surface and core structures of LJ nanoparticles have been analyzed in details. Density dependence and cooling rate effects on structure of the systems have been found and discussed. In addition, size dependence of structure and properties of nanoparticles has been analyzed in detail. Indeed, we found glass formation in monatomic LJ systems; however, their stability is not high. Evolution of structure and thermodynamics of the systems upon cooling from the melts was found. We also discussed annealing-induced crystallization of LJ glass.
Phase behavior of the 38-atom Lennard-Jones cluster
International Nuclear Information System (INIS)
Sehgal, Ray M.; Maroudas, Dimitrios; Ford, David M.
2014-01-01
We have developed a coarse-grained description of the phase behavior of the isolated 38-atom Lennard-Jones cluster (LJ 38 ). The model captures both the solid-solid polymorphic transitions at low temperatures and the complex cluster breakup and melting transitions at higher temperatures. For this coarse model development, we employ the manifold learning technique of diffusion mapping. The outcome of the diffusion mapping analysis over a broad temperature range indicates that two order parameters are sufficient to describe the cluster's phase behavior; we have chosen two such appropriate order parameters that are metrics of condensation and overall crystallinity. In this well-justified coarse-variable space, we calculate the cluster's free energy landscape (FEL) as a function of temperature, employing Monte Carlo umbrella sampling. These FELs are used to quantify the phase behavior and onsets of phase transitions of the LJ 38 cluster
Water in the presence of inert Lennard-Jones obstacles
Kurtjak, Mario; Urbic, Tomaz
2014-04-01
Water confined by the presence of a 'sea' of inert obstacles was examined. In the article, freely mobile two-dimensional Mercedes-Benz (MB) water put to a disordered, but fixed, matrix of Lennard-Jones disks was studied by the Monte Carlo computer simulations. For the MB water molecules in the matrix of Lennard-Jones disks, we explored the structures, hydrogen-bond-network formation and thermodynamics as a function of temperature and size and density of matrix particles. We found that the structure of model water is perturbed by the presence of the obstacles. Density of confined water, which was in equilibrium with the bulk water, was smaller than the density of the bulk water and the temperature dependence of the density of absorbed water did not show the density anomaly in the studied temperature range. The behaviour observed as a consequence of confinement is similar to that of increasing temperature, which can for a matrix lead to a process similar to capillary evaporation. At the same occupancy of space, smaller matrix molecules cause higher destruction effect on the absorbed water molecules than the bigger ones. We have also tested the hypothesis that at low matrix densities the obstacles induce an increased ordering and 'hydrogen bonding' of the MB model molecules, relative to pure fluid, while at high densities the obstacles reduce MB water structuring, as they prevent the fluid to form good 'hydrogen-bonding' networks. However, for the size of matrix molecules similar to that of water, we did not observe this effect.
A molecular dynamics study of Lennard-Jones physisorption on W(100)
International Nuclear Information System (INIS)
Broughton, J.Q.
1980-01-01
The physisorption of Xe on W(100) was modeled by Lennard-Jones pair-wise interaction potentials and the dynamics of coverages ranging from one to four adlayers obtained by molecular dynamics simulation. At 115 K, the first two layers were well-ordered and each adsorbed with c(2 x 2) symmetry. Further adsorption produced a surface similar to that of a distorted Xe(100) face. In accord with the work of Broughton and Woodcock, the top layers of the three- and four-adlayer coverages were rough and had liquid-like diffusion coefficients. The potential energies of all layers other than the first were similar, thus corroborating one of the postulates of BET theory. Generally, the effect of adsorbing a layer was to reduce the entropy of all those beneath. (orig.)
Longitudinal and bulk viscosities of Lennard-Jones fluids
Tankeshwar, K.; Pathak, K. N.; Ranganathan, S.
1996-12-01
Expressions for the longitudinal and bulk viscosities have been derived using Green Kubo formulae involving the time integral of the longitudinal and bulk stress autocorrelation functions. The time evolution of stress autocorrelation functions are determined using the Mori formalism and a memory function which is obtained from the Mori equation of motion. The memory function is of hyperbolic secant form and involves two parameters which are related to the microscopic sum rules of the respective autocorrelation function. We have derived expressions for the zeroth-, second-and fourth- order sum rules of the longitudinal and bulk stress autocorrelation functions. These involve static correlation functions up to four particles. The final expressions for these have been put in a form suitable for numerical calculations using low- order decoupling approximations. The numerical results have been obtained for the sum rules of longitudinal and bulk stress autocorrelation functions. These have been used to calculate the longitudinal and bulk viscosities and time evolution of the longitudinal stress autocorrelation function of the Lennard-Jones fluids over wide ranges of densities and temperatures. We have compared our results with the available computer simulation data and found reasonable agreement.
Vacancy behavior in a compressed fcc Lennard-Jones crystal
International Nuclear Information System (INIS)
Beeler, J.R. Jr.
1981-12-01
This computer experiment study concerns the determination of the stable vacancy configuration in a compressed fcc Lennard-Jones crystal and the migration of this defect in a compressed crystal. Isotropic and uniaxial compression stress conditions were studied. The isotropic and uniaxial compression magnitudes employed were 0.94 less than or equal to eta less than or equal to 1.5, and 1.0 less than or equal to eta less than or equal to 1.5, respectively. The site-centered vacancy (SCV) was the stable vacancy configuration whenever cubic symmetry was present. This includes all of the isotropic compression cases and the particular uniaxial compression case (eta = √2) that give a bcc structure. In addition, the SCV was the stable configuration for uniaxial compression eta 1.20, the SV-OP is an extended defect and, therefore, a saddle point for SV-OP migration could not be determined. The mechanism for the transformation from the SCV to the SV-OP as the stable form at eta = 1.29 appears to be an alternating sign [101] and/or [011] shear process
Spray flow-network flow transition of binary Lennard-Jones particle system
Inaoka, Hajime
2010-07-01
We simulate gas-liquid flows caused by rapid depressurization using a molecular dynamics model. The model consists of two types of Lennard-Jones particles, which we call liquid particles and gas particles. These two types of particles are distinguished by their mass and strength of interaction: a liquid particle has heavier mass and stronger interaction than a gas particle. By simulations with various initial number densities of these particles, we found that there is a transition from a spray flow to a network flow with an increase of the number density of the liquid particles. At the transition point, the size of the liquid droplets follows a power-law distribution, while it follows an exponential distribution when the number density of the liquid particles is lower than the critical value. The comparison between the transition of the model and that of models of percolation is discussed. The change of the average droplet size with the initial number density of the gas particles is also presented. © 2010 Elsevier B.V. All rights reserved.
Spray flow-network flow transition of binary Lennard-Jones particle system
Inaoka, Hajime; Yukawa, Satoshi; Ito, Nobuyasu
2010-01-01
We simulate gas-liquid flows caused by rapid depressurization using a molecular dynamics model. The model consists of two types of Lennard-Jones particles, which we call liquid particles and gas particles. These two types of particles are distinguished by their mass and strength of interaction: a liquid particle has heavier mass and stronger interaction than a gas particle. By simulations with various initial number densities of these particles, we found that there is a transition from a spray flow to a network flow with an increase of the number density of the liquid particles. At the transition point, the size of the liquid droplets follows a power-law distribution, while it follows an exponential distribution when the number density of the liquid particles is lower than the critical value. The comparison between the transition of the model and that of models of percolation is discussed. The change of the average droplet size with the initial number density of the gas particles is also presented. © 2010 Elsevier B.V. All rights reserved.
Single-site Lennard-Jones models via polynomial chaos surrogates of Monte Carlo molecular simulation
Energy Technology Data Exchange (ETDEWEB)
Kadoura, Ahmad, E-mail: ahmad.kadoura@kaust.edu.sa, E-mail: adil.siripatana@kaust.edu.sa, E-mail: shuyu.sun@kaust.edu.sa, E-mail: omar.knio@kaust.edu.sa; Sun, Shuyu, E-mail: ahmad.kadoura@kaust.edu.sa, E-mail: adil.siripatana@kaust.edu.sa, E-mail: shuyu.sun@kaust.edu.sa, E-mail: omar.knio@kaust.edu.sa [Computational Transport Phenomena Laboratory, The Earth Sciences and Engineering Department, The Physical Sciences and Engineering Division, King Abdullah University of Science and Technology, Thuwal 23955-6900 (Saudi Arabia); Siripatana, Adil, E-mail: ahmad.kadoura@kaust.edu.sa, E-mail: adil.siripatana@kaust.edu.sa, E-mail: shuyu.sun@kaust.edu.sa, E-mail: omar.knio@kaust.edu.sa; Hoteit, Ibrahim, E-mail: ibrahim.hoteit@kaust.edu.sa [Earth Fluid Modeling and Predicting Group, The Earth Sciences and Engineering Department, The Physical Sciences and Engineering Division, King Abdullah University of Science and Technology, Thuwal 23955-6900 (Saudi Arabia); Knio, Omar, E-mail: ahmad.kadoura@kaust.edu.sa, E-mail: adil.siripatana@kaust.edu.sa, E-mail: shuyu.sun@kaust.edu.sa, E-mail: omar.knio@kaust.edu.sa [Uncertainty Quantification Center, The Applied Mathematics and Computational Science Department, The Computer, Electrical and Mathematical Sciences and Engineering Division, King Abdullah University of Science and Technology, Thuwal 23955-6900 (Saudi Arabia)
2016-06-07
In this work, two Polynomial Chaos (PC) surrogates were generated to reproduce Monte Carlo (MC) molecular simulation results of the canonical (single-phase) and the NVT-Gibbs (two-phase) ensembles for a system of normalized structureless Lennard-Jones (LJ) particles. The main advantage of such surrogates, once generated, is the capability of accurately computing the needed thermodynamic quantities in a few seconds, thus efficiently replacing the computationally expensive MC molecular simulations. Benefiting from the tremendous computational time reduction, the PC surrogates were used to conduct large-scale optimization in order to propose single-site LJ models for several simple molecules. Experimental data, a set of supercritical isotherms, and part of the two-phase envelope, of several pure components were used for tuning the LJ parameters (ε, σ). Based on the conducted optimization, excellent fit was obtained for different noble gases (Ar, Kr, and Xe) and other small molecules (CH{sub 4}, N{sub 2}, and CO). On the other hand, due to the simplicity of the LJ model used, dramatic deviations between simulation and experimental data were observed, especially in the two-phase region, for more complex molecules such as CO{sub 2} and C{sub 2} H{sub 6}.
Single-site Lennard-Jones models via polynomial chaos surrogates of Monte Carlo molecular simulation
Kadoura, Ahmad Salim
2016-06-01
In this work, two Polynomial Chaos (PC) surrogates were generated to reproduce Monte Carlo (MC) molecular simulation results of the canonical (single-phase) and the NVT-Gibbs (two-phase) ensembles for a system of normalized structureless Lennard-Jones (LJ) particles. The main advantage of such surrogates, once generated, is the capability of accurately computing the needed thermodynamic quantities in a few seconds, thus efficiently replacing the computationally expensive MC molecular simulations. Benefiting from the tremendous computational time reduction, the PC surrogates were used to conduct large-scale optimization in order to propose single-site LJ models for several simple molecules. Experimental data, a set of supercritical isotherms, and part of the two-phase envelope, of several pure components were used for tuning the LJ parameters (ε, σ). Based on the conducted optimization, excellent fit was obtained for different noble gases (Ar, Kr, and Xe) and other small molecules (CH4, N2, and CO). On the other hand, due to the simplicity of the LJ model used, dramatic deviations between simulation and experimental data were observed, especially in the two-phase region, for more complex molecules such as CO2 and C2 H6.
Enhancement of the droplet nucleation in a dense supersaturated Lennard-Jones vapor
Energy Technology Data Exchange (ETDEWEB)
Zhukhovitskii, D. I., E-mail: dmr@ihed.ras.ru [Joint Institute of High Temperatures, Russian Academy of Sciences, Izhorskaya 13, Bd. 2, 125412 Moscow (Russian Federation)
2016-05-14
The vapor–liquid nucleation in a dense Lennard-Jones system is studied analytically and numerically. A solution of the nucleation kinetic equations, which includes the elementary processes of condensation/evaporation involving the lightest clusters, is obtained, and the nucleation rate is calculated. Based on the equation of state for the cluster vapor, the pre-exponential factor is obtained. The latter diverges as a spinodal is reached, which results in the nucleation enhancement. The work of critical cluster formation is calculated using the previously developed two-parameter model (TPM) of small clusters. A simple expression for the nucleation rate is deduced and it is shown that the work of cluster formation is reduced for a dense vapor. This results in the nucleation enhancement as well. To verify the TPM, a simulation is performed that mimics a steady-state nucleation experiments in the thermal diffusion cloud chamber. The nucleating vapor with and without a carrier gas is simulated using two different thermostats for the monomers and clusters. The TPM proves to match the simulation results of this work and of other studies.
Fowler's approximation for the surface tension and surface energy of Lennard-Jones fluids revisited
International Nuclear Information System (INIS)
Mulero, A; Galan, C; Cuadros, F
2003-01-01
We present a detailed study of the validity of Fowler's approximation for calculating the surface tension and the surface energy of Lennard-Jones fluids. To do so, we consider three different explicit analytical expressions for the radial distribution function (RDF), including one proposed by our research group, together with very accurate expressions for the liquid and vapour densities, also proposed by our group. The calculation of the surface tension from the direct correlation function using both the Percus-Yevick and the hypernetted-chain approximations is also considered. Finally, our results are compared with those obtained by other authors by computer simulations or through relevant theoretical approximations. In particular, we consider the analytical expression proposed by Kalikmanov and Hofmans (1994 J. Phys.: Condens. Matter 6 2207-14) for the surface tension. Our results indicate that the values for the surface energy in Fowler's approximation obtained by other authors are adequate, and can be calculated from the RDF models. For the surface tension, however, the values considered as valid in previous works seem to be incorrect. The correct values can be obtained from our model for the RDF or from the Kalikmanov and Hofmans expression with suitable inputs
Simulation of depositions of a Lennard-Jones cluster on a crystalline surface
International Nuclear Information System (INIS)
Saitoh, Kuniyasu; Hayakawa, Hisao
2009-01-01
Depositions of amorphous Lennard-Jones clusters on a crystalline surface are numerically investigated. From the results of the molecular dynamics simulation, we found that the deposited clusters exhibit a transition from multilayered adsorption to monolayered adsorption at a critical incident speed. Employing the energy conservation law, we can explain the behavior of the ratio of the number of atoms adsorbed on the substrate to the cluster size. The boundary shape of the deposited cluster depends strongly on the incident speed, and some unstable modes grow during the spread of the deposited cluster on the substrate. We also discuss the wettability between different Lennard-Jones atoms. (author)
RISM theory distribution functions for Lennard--Jones interaction site fluids
International Nuclear Information System (INIS)
Johnson, E.; Hazoume, R.P.
1978-01-01
Reference interaction site model (RISM) theory distribution functions for Lennard-Jones interaction site fluids are discussed. The comparison with computer simulation results suggests that these distribution functions are as accurate as RISM distribution functions for fused hard sphere molecular fluids
Formation of global energy minimim structures in the growth process of Lennard-Jones clusters
DEFF Research Database (Denmark)
Solov'yov, Ilia; Koshelev, Andrey; Shutovich, Andrey
2003-01-01
that in this way all known global minimum structures of the Lennard-Jones (LJ) clusters can be found. Our method provides an efficient tool for the calculation and analysis of atomic cluster structure. With its use we justify the magic numbers sequence for the clusters of noble gases atoms and compare...
Application of the RISM theory to Lennard-Jones interaction site molecular fluids
International Nuclear Information System (INIS)
Johnson, E.; Hazoume, R.P.
1979-01-01
It seems that reference interaction site model (RISM) theory atom--atom distribution functions have been obtained directly from the RISM equations only for fused hard sphere molecular fluids. RISM distribution functions for Lennard-Jones interaction site fluids are presented. Results presented suggest that these distribution functions are as accurate as RISM distribution functions for fused hard sphere molecular fluids
Atomic size effect on the formation of ionized cluster beam epitaxy in Lennard-Jones systems
International Nuclear Information System (INIS)
Hsieh Horngming; Averback, R.S.
1991-01-01
Ionized cluster beam deposition is studied by molecular dynamics simulations in which the atomic size of incident cluster atoms is different from the size of substrate atoms. Lennard-Jones interatomic potentials are used for the two-component system. The results provide the morphologies of the overlayers for various atomic sizes and are compared to simulation results of molecular beam epitaxy. (orig.)
DEFF Research Database (Denmark)
D'ovidio, Francesco; Bohr, Henrik; Lindgård, Per-Anker
2005-01-01
We study the propagation of solitons along the hydrogen bonds of an alpha helix. Modeling the hydrogen and peptide bonds with Lennard-Jones potentials, we show that the solitons can appear spontaneously and have long lifetimes. Remarkably, even if no explicit solution is known for the Lennard-Jones...... potential, the solitons can be characterized analytically with a good quantitative agreement using formulas for a Toda potential with parameters fitted to the Lennard-Jones potential. We also discuss and show the robustness of the family of periodic solutions called cnoidal waves, corresponding to phonons...
Molecular dynamics study of the hydration of Lennard-Jones solutes
International Nuclear Information System (INIS)
Geiger, A.; Rahman, A.; Stillinger, F.H.
1979-01-01
In order to clarify the nature of hydrophobic interactions in water, we have used the molecular dynamics simulation method to study a system comprising two Lennard-Jones solute particles and 214 water molecules. Although the solutes were placed initially in contact, forces in the system drive them slightly apart to permit formation of vertex-sharing solvent ''cages.'' Definite orientational preferences have been observed for water molecules in the first solvation layer around the Lennard-Jones solutes; these preferences are loosely reminiscent of structure in clathrates. Nevertheless, substantial local disorder is obviously present. The dynamical data show that translational and rotational motions of solvation--sheath water molecules are perceptibly slower (by at least 20%) than those in pure bulk water
Collision kernels in the eikonal approximation for Lennard-Jones interaction potential
International Nuclear Information System (INIS)
Zielinska, S.
1985-03-01
The velocity changing collisions are conveniently described by collisional kernels. These kernels depend on an interaction potential and there is a necessity for evaluating them for realistic interatomic potentials. Using the collision kernels, we are able to investigate the redistribution of atomic population's caused by the laser light and velocity changing collisions. In this paper we present the method of evaluating the collision kernels in the eikonal approximation. We discuss the influence of the potential parameters Rsub(o)sup(i), epsilonsub(o)sup(i) on kernel width for a given atomic state. It turns out that unlike the collision kernel for the hard sphere model of scattering the Lennard-Jones kernel is not so sensitive to changes of Rsub(o)sup(i) as the previous one. Contrary to the general tendency of approximating collisional kernels by the Gaussian curve, kernels for the Lennard-Jones potential do not exhibit such a behaviour. (author)
Fluctuations and thermodynamic response functions in a Lennard-Jones solid
International Nuclear Information System (INIS)
Li, M.; Johnson, W.L.
1992-01-01
Thermodynamic response functions of a nearest-neighbor Lennard-Jones solid--heat capacity, thermal-expansion coefficient, compressibility, and elastic constants--are calculated directly from fluctuations using molecular-dynamics simulations. The algorithm used is the earlier Parrinello-Rahman molecular dynamics modified to take into account symmetry and rotation invariance of the system under investigation. The convergence is very fast and results are in good agreement with existing Monte Carlo and molecular-dynamics results
Dynamics of an assembly of finite-size Lennard-Jones spheres
International Nuclear Information System (INIS)
Singh, P.
1996-01-01
The time-averaged Fourier spectra of the number density, velocity, and force fields are obtained numerically for an assembly of spherical particles interacting via the Lennard-Jones potential. The magnitude spectra determine the dominant wave numbers, and the phase difference between the Lennard-Jones force and number density spectra determines the nature of the particle dynamics. The latter is used to show that for every wave number k there is a critical frequency ω c (k), such that when ω c (k) the phase difference is π/2 and when ω approx-gt ω c (k) the phase difference is -π/2. The ratio of the frequency and the wave number at which the phase difference changes sign is used to define an effective sound speed for the particle system. The effective sound speed is shown to be a function of the dimensionless wave number, and is locally minimum at the same dimensionless wave numbers for which the static structure factor is minimum. It is also shown that the dynamical response of the particle system for waves with speeds greater than the effective sound speed is similar to the response of the hyperbolic systems of equations, and for waves with speeds smaller than the effective sound speed the response is similar to the response of the elliptic systems. The convection effects are shown to be of the same order of magnitude as the Lennard-Jones forces, and the change of type of the equations from hyperbolic to elliptic occurs when the magnitude of the convection term is comparable to the magnitude of the Lennard-Jones force term. It is also shown that the change of type cannot occur in a theory where the convection term is neglected. copyright 1996 The American Physical Society
Stability of relaxed Lennard-Jones models made of 500 to 6000 atoms
International Nuclear Information System (INIS)
Raoult, B.; Farges, J.; Feraudy, M.F. de; Torchet, G.
1989-01-01
We present a study of the stability of clusters models made of a number N of atoms in the range 500 to 6000 atoms, freely interacting through the Lennard-Jones potential. The potential energy per atom, calculated for relaxed models, shows that stable models belong to an icosahedral sequence when N<1600 and to a decahedral sequence beyond. A coexistence size range of both structures is discussed in connection with experimental results on argon clusters in free jet expansions. (orig.)
Metastability, spectrum, and eigencurrents of the Lennard-Jones-38 network
International Nuclear Information System (INIS)
Cameron, Maria K.
2014-01-01
We develop computational tools for spectral analysis of stochastic networks representing energy landscapes of atomic and molecular clusters. Physical meaning and some properties of eigenvalues, left and right eigenvectors, and eigencurrents are discussed. We propose an approach to compute a collection of eigenpairs and corresponding eigencurrents describing the most important relaxation processes taking place in the system on its way to the equilibrium. It is suitable for large and complex stochastic networks where pairwise transition rates, given by the Arrhenius law, vary by orders of magnitude. The proposed methodology is applied to the network representing the Lennard-Jones-38 cluster created by Wales's group. Its energy landscape has a double funnel structure with a deep and narrow face-centered cubic funnel and a shallower and wider icosahedral funnel. However, the complete spectrum of the generator matrix of the Lennard-Jones-38 network has no appreciable spectral gap separating the eigenvalue corresponding to the escape from the icosahedral funnel. We provide a detailed description of the escape process from the icosahedral funnel using the eigencurrent and demonstrate a superexponential growth of the corresponding eigenvalue. The proposed spectral approach is compared to the methodology of the Transition Path Theory. Finally, we discuss whether the Lennard-Jones-38 cluster is metastable from the points of view of a mathematician and a chemical physicist, and make a connection with experimental works
Analytic Debye-Grüneisen equation of state for a generalized Lennard-Jones solids
Institute of Scientific and Technical Information of China (English)
孙久勋; 吴强; 蔡灵仓; 经福谦
2003-01-01
The approximate method to treat the practical quantum anharmonic solids proposed by Hardy,Lacks and Shukla is reformulated with explicit physical meanings.It is shown that the quantum effect is important at low temperature,it can be treated in the harmonic framework; and the anharmonic effect is important at high temperature and tends to zero at low temperature,it can be treated by using a classical approximation.The alternative formulation is easier for various applications,and is applied to a Debye-Gruneisen solid with the generalized Lennard-Jones intermolecular interaction.The expressions for the Debye temperature and Gruneisen parameter as a function of volume are analytically derived.The analytic equation of state is applied to predict the thermodynamic properties of solid xenon at normal-pressure with the nearest-neighbour Lennard-Jones interaction,and is further applied to research the properties of solid xenon and krypton at high pressure by using an all-neighbour Lennard-Jones interaction.The theoretical results are in agreement with the experiments.
Reinisch, S; Schweiger, K; Pablik, E; Collet-Fenetrier, B; Peyrin-Biroulet, L; Alfaro, I; Panés, J; Moayyedi, P; Reinisch, W
2016-09-01
The Lennard-Jones criteria are considered the gold standard for diagnosing Crohn's disease (CD) and include the items granuloma, macroscopic discontinuity, transmural inflammation, fibrosis, lymphoid aggregates and discontinuous inflammation on histology. The criteria have never been subjected to a formal validation process. To develop a validated and improved diagnostic index based on the items of Lennard-Jones criteria. Included were 328 adult patients with long-standing CD (median disease duration 10 years) from three centres and classified as 'established', 'probable' or 'non-CD' by Lennard-Jones criteria at time of diagnosis. Controls were patients with ulcerative colitis (n = 170). The performance of each of the six diagnostic items of Lennard-Jones criteria was modelled by logistic regression and a new index based on stepwise backward selection and cut-offs was developed. The diagnostic value of the new index was analysed by comparing sensitivity, specificity and accuracy vs. Lennard-Jones criteria. By Lennard-Jones criteria 49% (n = 162) of CD patients would have been diagnosed as 'non-CD' at time of diagnosis (sensitivity/specificity/accuracy, 'established' CD: 0.34/0.99/0.67; 'probable' CD: 0.51/0.95/0.73). A new index was derived from granuloma, fibrosis, transmural inflammation and macroscopic discontinuity, but excluded lymphoid aggregates and discontinuous inflammation on histology. Our index provided improved diagnostic accuracy for 'established' and 'probable' CD (sensitivity/specificity/accuracy, 'established' CD: 0.45/1/0.72; 'probable' CD: 0.8/0.85/0.82), including the subgroup isolated colonic CD ('probable' CD, new index: 0.73/0.85/0.79; Lennard-Jones criteria: 0.43/0.95/0.69). We developed an index based on items of Lennard-Jones criteria providing improved diagnostic accuracy for the differential diagnosis between CD and UC. © 2016 John Wiley & Sons Ltd.
Karbowniczek, Paweł; Chrzanowska, Agnieszka
2017-11-01
A two-dimensional Lennard-Jones system in a circular and rotating container has been studied by means of molecular dynamics technique. A nonequilibrium transition to the rotating stage has been detected in a delayed time since an instant switching of the frame rotation. This transition is attributed to the increase of the density at the wall because of the centrifugal force. At the same time the phase transition occurs, the inner system changes its configuration of the solid-state type into the liquid type. Impact of angular frequency and molecular roughness on the transport properties of the nonrotating and rotating systems is analyzed.
Third-order WKBJ eigenvalues for Lennard-Jones and Varshni V potentials
International Nuclear Information System (INIS)
Kesarwani, R.N.; Varshni, Y.P.
1978-01-01
The WKBJ method is applied to the third order for obtaining the eigenvalues for the fifth potential of Varshni, and the relevant integrals are analytically evaluated. Numerical results are obtained for the Lennard-Jones Potential, which is a special case of the Varshni V potential, and are compared to the results of Harrison and Bernstein obtained by a numerical integration of the wave equation. Error estimates are made. It is shown that for diatomic potentials, the Langer correction is not needed if the WKBJ approximation is carried to second and higher orders. (author)
Self-diffusion coefficients of the metastable Lennard-Jones vapor
International Nuclear Information System (INIS)
Nie Chu; Zhou Youhua; Marlow, W H; Hassan, Y A
2008-01-01
Self-diffusion coefficients of a metastable Lennard-Jones vapor were obtained using the memory function formalism and the frequency moments of the velocity autocorrelation function at reduced temperatures from 0.75 to 1.0. The radial density distribution functions used to evaluate the second, fourth and sixth frequency moments of the velocity autocorrelation function were obtained from the restricted canonical ensemble Monte Carlo simulation (Corti and Debenedetti 1994 Chem. Eng. Sci. 49 2717). The self-diffusion coefficients at reduced temperature 0.75 do not vary monotonically as the density increases, and for the other three temperatures the self-diffusion coefficients vary normally
Self-diffusion coefficients of the metastable Lennard-Jones vapor
Energy Technology Data Exchange (ETDEWEB)
Nie Chu; Zhou Youhua [School of Physics and Information Engineering, Jianghan University, Wuhan 430056 (China); Marlow, W H; Hassan, Y A [Department of Nuclear Engineering, Texas A and M University, College Station, TX 77843 (United States)], E-mail: yhzhou@jhun.edu.cn
2008-10-15
Self-diffusion coefficients of a metastable Lennard-Jones vapor were obtained using the memory function formalism and the frequency moments of the velocity autocorrelation function at reduced temperatures from 0.75 to 1.0. The radial density distribution functions used to evaluate the second, fourth and sixth frequency moments of the velocity autocorrelation function were obtained from the restricted canonical ensemble Monte Carlo simulation (Corti and Debenedetti 1994 Chem. Eng. Sci. 49 2717). The self-diffusion coefficients at reduced temperature 0.75 do not vary monotonically as the density increases, and for the other three temperatures the self-diffusion coefficients vary normally.
Evidence of hexatic phase formation in two-dimensional Lennard-Jones binary arrays
International Nuclear Information System (INIS)
Li, M.; Johnson, W.L.; Goddard, W.A. III
1996-01-01
We report evidence of the hexatic phase formation in Lennard-Jones binary substitutional random arrays from isothermal-isobaric molecular-dynamics simulations. The hexatic phase is analogous to those predicted in Kosterlitz-Thouless theory of melting that is characterized by short-range translational order and quasi-long-range orientational order. At the crystal to hexatic phase transition, dislocation pairs are observed to unbind into isolated dislocations. Further disordering of the hexatic phase, however, does not lead to dissociation of dislocations into disclinations. Instead, the dislocations become clustered and form dislocation networks which results in formation of amorphous phases. copyright 1996 The American Physical Society
Crystallisation of a Lennard-Jones fluid by large scale molecular dynamics simulation
International Nuclear Information System (INIS)
Snook, I.
1998-01-01
Full text: The evolution of the structure of a large system of atoms interacting via a Lennard-Jones pair potential was simulated by the use of the Molecular Dynamics computer simulation technique. The system was initially equilibrated in the one phase region of the phase diagram at a temperature above critical then a temperature quench was performed which placed the system in a region were the single fluid phase was unstable. Quenches to below the triple point temperature gave rise to crystallisation The mechanism and final morphology is shown to depend strongly on the starting conditions e.g. the starting density
Nonlinear transport processes and fluid dynamics: Cylindrical Couette flow of Lennard-Jones fluids
International Nuclear Information System (INIS)
Khayat, R.E.; Eu, B.C.
1988-01-01
In this paper we report on calculations of flow profiles for cylindrical Couette flow of a Lennard-Jones fluid. The flow is subjected to a temperature gradient and thermoviscous effects are taken into consideration. We apply the generalized fluid dynamic equations which are provided by the modified moment method for the Boltzmann equation reported previously. The results of calculations are in good agreement with the Monte Carlo direct simulation method by K. Nanbu [Phys. Fluids 27, 2632 (1984)] for most of Knudsen numbers for which the simulation data are available
International Nuclear Information System (INIS)
Kim, Soon-Chul; Lee, Song Hi
2004-01-01
A density functional perturbation approximation (DFPT), which is based both on the fundamental-measure theory (FMT) to the hard-sphere repulsion and on the weighted-density approximations (WDAs) to the attractive contribution, has been proposed for studying the structural properties of model fluids with an attractive part of the potential. The advantage of the present theory is the simplicity of the calculation of the weight function due to the attractive contribution. It has been applied to predict the equilibrium particle density distributions and adsorption isotherms of Lennard-Jones fluids at interfaces. The theoretical results show that the present theory describes quite well the adsorption isotherms of a Lennard-Jones ethane in a graphite slit pore as well as the equilibrium particle density distributions of a Lennard-Jones fluid near a planar slit pore
Binding energy of large icosahedral and cuboctahedral Lennard-Jones clusters
International Nuclear Information System (INIS)
Northby, J.A.; Xie, J.
1989-01-01
It is widely believed that the lowest energy configurations for small rare gas clusters have icosahedral symmetry. This contrasts with the bulk crystal structures which have cuboctahedral fcc symmetry. It is of interest to understand the transition between this finite and bulk behavior. To model this transition in rare gas clusters we have undertaken optimization studies within the Lennard-Jones pair potential model. Using a combination of Monte Carlo and Partan Search optimization methods, the lowest energy relaxed structures of Lennard-Jones clusters having icosahedral and cuboctahedral symmetry were found. Studies were performed for complete shell clusters ranging in size from one shell having 13 atoms to 14 shells having 10,179 atoms. It was found that the icosahedral structures are lower in energy than the cuboctahedral structures for cluster sizes having 13 shells or fewer. Additional studies were performed using the more accurate Aziz-Chen [HFD-C] pair potential parameterized for argon. The conclusions appear to be relatively insensitive to the form of the potential. (orig.)
An accurate expression for radial distribution function of the Lennard-Jones fluid
International Nuclear Information System (INIS)
Morsali, Ali; Goharshadi, Elaheh K.; Ali Mansoori, G.; Abbaspour, Mohsen
2005-01-01
A simple and accurate expression for radial distribution function (RDF) of the Lennard-Jones fluid is presented. The expression explicitly states the RDF as a continuous function of reduced interparticle distance, temperature, and density. It satisfies the limiting conditions of zero density and infinite distance imposed by statistical thermodynamics. The distance dependence of this expression is expressed by an equation which contains 11 adjustable parameters. These parameters are fitted to 353 RDF data, obtained by molecular dynamics calculations, and then expressed as functions of reduced distance, temperature and density. This expression, having a total of 65 constants, reproduces the RDF data with an average root-mean-squared deviation of 0.0152 for the range of state variables of 0.5= * = * = * =ρσ 3 are reduced temperature and density, respectively). The expression predicts the pressure and the internal energy of the Lennard-Jones fluid with an uncertainty that is comparable to that obtained directly from the molecular dynamics simulations
Fowler's approximation for the surface tension and surface energy of Lennard-Jones fluids revisited
Energy Technology Data Exchange (ETDEWEB)
Mulero, A [Departamento de Fisica, Universidad de Extremadura, 06071-Badajoz (Spain); Galan, C [Departamento de Fisica, Universidad de Extremadura, 06071-Badajoz (Spain); Cuadros, F [Departamento de Fisica, Universidad de Extremadura, 06071-Badajoz (Spain)
2003-04-16
We present a detailed study of the validity of Fowler's approximation for calculating the surface tension and the surface energy of Lennard-Jones fluids. To do so, we consider three different explicit analytical expressions for the radial distribution function (RDF), including one proposed by our research group, together with very accurate expressions for the liquid and vapour densities, also proposed by our group. The calculation of the surface tension from the direct correlation function using both the Percus-Yevick and the hypernetted-chain approximations is also considered. Finally, our results are compared with those obtained by other authors by computer simulations or through relevant theoretical approximations. In particular, we consider the analytical expression proposed by Kalikmanov and Hofmans (1994 J. Phys.: Condens. Matter 6 2207-14) for the surface tension. Our results indicate that the values for the surface energy in Fowler's approximation obtained by other authors are adequate, and can be calculated from the RDF models. For the surface tension, however, the values considered as valid in previous works seem to be incorrect. The correct values can be obtained from our model for the RDF or from the Kalikmanov and Hofmans expression with suitable inputs.
DEFF Research Database (Denmark)
Cotterill, Rodney M J; Madsen, J.
1986-01-01
Sections of configuration space for Lennard-Jones matter were obtained by probing all the normal-mode energy profiles, following diagonalization of the dynamical matrix for a 240-particle system. For the crystal and sufficiently cold glass, these are single welled, whereas increasing numbers...... of double wells occur as the glass is warmed toward the fluid. This indicates that there might be a fundamental difference between the topologies of the constant-potential-energy hypersurfaces of crystalline and noncrystalline Lennard-Jones matter....
DEFF Research Database (Denmark)
Friisberg, Ida Marie; Costigliola, Lorenzo; Dyre, Jeppe C.
2017-01-01
This paper investigates the relation between the density-scaling exponent γ and the virial potentialenergy coefficient R at several thermodynamic state points in three dimensions for the generalized (2n, n) Lennard-Jones (LJ) system for n = 4, 9, 12, 18, as well as for the standard n = 6 LJ syste...
Viscous Growth in Spinodal Decomposition of the Two-component Lennard-Jones Model in Two Dimensions
DEFF Research Database (Denmark)
Laradji, M.; Toxvaerd, S.; Mouritsen, Ole G.
1997-01-01
The dynamics of phase separation of a two-component Lennard-Jones model in three dimensions is investigated by means of large scale molecular dynamics simulation. A systematic study over a wide range of quench temperatures within the coexistence region shows that the binary system reaches...
The Monte Carlo dynamics of a binary Lennard-Jones glass-forming mixture
International Nuclear Information System (INIS)
Berthier, L; Kob, W
2007-01-01
We use a standard Monte Carlo algorithm to study the slow dynamics of a binary Lennard-Jones glass-forming mixture at low temperature. We find that the Monte Carlo approach is by far the most efficient way to simulate a stochastic dynamics since the relaxation is about 10 times faster than in Brownian dynamics and about 30 times faster than in stochastic dynamics. Moreover, the average dynamical behaviour of the system is in quantitative agreement with that obtained using Newtonian dynamics, apart from at very short times where thermal vibrations are suppressed. We show, however, that dynamic fluctuations quantified by four-point dynamic susceptibilities do retain a dependence on the microscopic dynamics, as recently predicted theoretically
The effect of atom mismatch on the fragility of supercooled Lennard-Jones binary mixtures
International Nuclear Information System (INIS)
Sun Minhua; Sun Yongli; Wang Aiping; Ma Congxiao; Li Jiayun; Cheng Weidong; Liu Fang
2006-01-01
The shear viscosity of the well-known binary Lennard-Jones mixture is simulated under constant temperature and constant volume conditions (NVT) by a molecular-dynamics (MD) method. The effect of atomic size mismatch on the fragility parameter and glass-forming ability is studied. The fragility parameters calculated from shear viscosity data decrease with the increment of the atomic size mismatch. The value of the fragility changes from 168.963 to 22.976 when the mismatch changes from 0.023 to 0.25. It is shown that the fragility parameter is sensitive to the atomic size mismatch. The calculated pair distribution functions and mean square displacements indicate that the glass-forming ability increases with the atomic size mismatch
Dynamics of vacancies in two-dimensional Lennard-Jones crystals
Yao, Zhenwei; Olvera de La Cruz, Monica
2015-03-01
Vacancies represent an important class of crystallographic defects, and their behaviors can be strongly coupled with relevant material properties. We report the rich dynamics of vacancies in two-dimensional Lennard-Jones crystals in several thermodynamic states. Specifically, we numerically observe significantly faster diffusion of the 2-point vacancy with two missing particles in comparison with other types of vacancies; it opens the possibility of doping 2-point vacancies into atomic materials to enhance atomic migration. In addition, the resulting dislocations in the healing of a long vacancy suggest the intimate connection between vacancies and topological defects that may provide an extra dimension in the engineering of defects in extensive crystalline materials for desired properties. We thank the financial support from the U.S. Department of Commerce, National Institute of Standards and Technology, the Office of the Director of Defense Research and Engineering (DDR&E) and the Air Force Office of Scientific Research.
Thermal conductivity of the Lennard-Jones fluid: An empirical correlation
International Nuclear Information System (INIS)
Bugel, Mathilde; Galliero, Guillaume
2008-01-01
In this work, is presented an empirical correlation on the thermal conductivity of the Lennard-Jones fluid based on extensive non-equilibrium molecular dynamics simulations results (103 points). Finite size and cutoff radius effects are investigated and taken into account to develop the correlation. This last, composed of low-density, residual and critical enhancement contributions, is built for a wide range of thermodynamics states, even at the vicinity of the critical point, and yields an average absolute deviation of 1.29% compared to our simulations. In addition, a careful analysis of the different contributions to the microscopic flux is carried out which sheds light on the underlying mechanism of the results. Finally, are discussed the limitations of the proposed model when applied to real simple fluids and mixtures using a standard corresponding states scheme and the van der Waals one-fluid approximation
Crystal phases of a glass-forming Lennard-Jones mixture
International Nuclear Information System (INIS)
Fernandez, Julian R.; Harrowell, Peter
2003-01-01
We compare the potential energy at zero temperature of a range of crystal structures for a glass-forming binary mixture of Lennard-Jones particles. The lowest-energy ordered state consists of coexisting phases of a single component face centered cubic structure and an equimolar cesium chloride structure. An infinite number of layered crystal structures are identified with energies close to this ground state. We demonstrate that the finite size increase of the energy of the coexisting crystal with incoherent interfaces is sufficient to destabilize this ordered phase in simulations of typical size. Two specific local coordination structures are identified as of possible structural significance in the amorphous state. We observe rapid crystal growth in the equimolar mixture
Simulasi Sifat Fisis Model Molekuler Dinamik Gas Argon dengan Potensial Lennard-Jones
Directory of Open Access Journals (Sweden)
Wira Bahari Nurdin
2014-01-01
Full Text Available DOWNLOAD PDFTelah dilakukan pembuatan dan pengujian suatu simulasi tentang sifat fisis gasargon dengan menggunakan dinamika molekuler menggunakan potensial Lennard-Jonesdalam sistem terisolasi (ensemble mikrokanonik. Jumlah molekul, energi total sistem danluas kotak simulasi telah divariasikan. Untuk menghitung perubahan posisi digunakanalgoritma Verlet. Sifat fisis yang ditentukan dalam simulasi adalah temperatur dan energitotal sistem untuk menentukan adanya fase transisi. Dari hasil simulasi, terdapatkesesuaian antara simulasi dengan gas argon dan tidak diperoleh adanya fase transisi.Kata kunci: Simulasi dinamika molekul, argon, potensial Lennard-Jones, ensemblemikrokanonik, algoritma Verlet
Shear viscosity of the Lennard-Jones fluid near the triple point: Green-Kubo results
International Nuclear Information System (INIS)
Erpenbeck, J.J.
1988-01-01
The long-standing disagreement over the shear viscosity coefficient of the Lennard-Jones fluid near the triple point is reexamined through a series of very extensive Monte Carlo molecular-dynamics calculations of this transport coefficient based on the Green-Kubo theory. The stress autocorrelation function is shown to exhibit a slow decay, principally in the kinetic-potential and the potential-potential terms, which is large compared with the kinetic-kinetic long-time tail predicted by simple mode-coupling theory. Nonetheless, the viscosity coefficient, exclusive of any correction for this tail for times greater than are accessible numerically, is found to agree with that of Schoen and Hoheisel (who discounted the existence of such a tail) as well as nonequilibrium molecular-dynamics calculations. The large value of the viscosity coefficient found by Levesque and co-workers for 864 particles is brought into statistical agreement with the present results by a modest, but not unrealistic, increase in its statistical uncertainty. The pressure is found to exhibit an anomalous dependence on the size of the system, but the viscosity as well as the self-diffusion constant appear to be linear in the inverse of the number of particles, within the precision of our calculations. The viscosity coefficient, including a long-time-tail contribution based on the extended mode-coupling theory is (3.796 +- 0.068)σepsilon-c/m)/sup 1/2/ for the Lennard-Jones potential, fitted to a cubic spline, and (3.345 +- 0.068)σepsilon-c/m)/sup 1/2/ for the potential truncated at 2.5σ
International Nuclear Information System (INIS)
Vogelsang, R.; Hoheisel, C.
1987-01-01
For a large region of dense fluid states of a Lennard-Jones system, they have calculated the friction coefficient by the force autocorrelation function of a Brownian-type particle by molecular dynamics (MD). The time integral over the force autocorrelation function showed an interesting behavior and the expected plateau value when the mass of the Brownian particle was chosen to be about a factor of 100 larger than the mass of the fluid particle. Sufficient agreement was found for the friction coefficient calculated by this way and that obtained by calculations of the self-diffusion coefficient using the common relation between these coefficients. Furthermore, a modified friction coefficient was determined by integration of the force autocorrelation function up to the first maximum. This coefficient can successfully be used to derive a reasonable soft part of the friction coefficient necessary for the Rice-Allnatt approximation for the shear velocity and simple liquids
Energy Technology Data Exchange (ETDEWEB)
Mamedov, Bahtiyar A. [Department of Physics, Gaziosmanpaşa University, 60250, Tokat (Turkey); Somuncu, Elif; Askerov, Iskender M. [Department of Physics, Giresun University, Giresun (Turkey)
2016-08-10
In this work, a new theoretical approach is proposed for calculating fourth virial coefficient with Lennard-Jones potential. The established algorithm can be used to evaluate the thermodynamics properties and the intermolecular interaction potentials of liquids and gases with an improved accuracy. Note that the evaluation of the high-order virial coefficients is very valuable for accurate calculation of thermodynamic parameters. By using the suggested method, the fourth virial coefficient of CH{sub 4}, Ar, C{sub 2}H{sub 6} and SF{sub 6} molecules are evaluated. The calculation results are useful for accurate interpretation of the experimental data and of the determination of related physical properties.
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Adebayo, G.A.; Anusionwu, B.C.; Njah, A.N.; Adeniran, O.J.; Mathew, B.; Sunmonu, R.S.
2009-01-01
Arising from the inability of theoretical calculations to give accurate descriptions of (shear) viscosity in rare gases at high densities, we investigated the likely cause of discrepancy between theory and experiments. Molecular Dynamics simulations were performed to calculate transport coefficients and collision frequency of rare gases at high densities and different temperatures using a Lennard-Jones modelled pair potential. The results, when compared with experiments show an underestimation of the viscosity calculated through the Green-Kubo formalism, but in agreement with some other calculations performed by other groups. In the present work the origin of the underestimation is considered. Analyses of the transport coefficients show a very high collision frequency which suggests an atom may spend much less time in the neighbourhood of the fields of force of another atom and that the distribution in the systems studied adjusts itself to a nearly Maxwellian type which resulted in a locally and temporarily slowly varying temperature. We show that the time spent in the fields of force is so small compared with relaxation time thereby leading to a possible reduction in local velocity auto-correlation between atoms. (author)
A test of the mean density approximation for Lennard-Jones mixtures with large size ratios
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Ely, J.F.
1986-01-01
The mean density approximation for mixture radial distribution functions plays a central role in modern corresponding-states theories. This approximation is reasonably accurate for systems that do not differ widely in size and energy ratios and which are nearly equimolar. As the size ratio increases, however, or if one approaches an infinite dilution of one of the components, the approximation becomes progressively worse, especially for the small molecule pair. In an attempt to better understand and improve this approximation, isothermal molecular dynamics simulations have been performed on a series of Lennard-Jones mixtures. Thermodynamic properties, including the mixture radial distribution functions, have been obtained at seven compositions ranging from 5 to 95 mol%. In all cases the size ratio was fixed at two and three energy ratios were investigated, 22 / 11 =0.5, 1.0, and 1.5. The results of the simulations are compared with the mean density approximation and a modification to integrals evaluated with the mean density approximation is proposed
Thermodynamic equivalence between the Lennard-Jones and hard-core attractive Yukawa systems
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Kadiri, Y.; Albaki, R.; Bretonnet, J.L.
2008-01-01
The investigation of the thermodynamic properties of the Lennard-Jones (LJ) fluid is made by means of a system of particles interacting with a potential of hard-core plus attractive Yukawa tail (HCY). Due to the similarity between the LJ potential and the HCY potential in its overall form, it is worthwhile seeking to approximate the LJ potential in much the same way that the hard-sphere reference potential has been so used. The study consists in describing the thermodynamics of the LJ fluid in terms of the equivalent HCY system, whose the properties are known accurately, by means of mapping the thermodynamic quantities for the HCY potential parameters. The method is feasible owing to a convenient analytical expression of the Helmholtz free energy from the mean-spherical approximation expanded in power of the inverse temperature. Two different procedures are used to determine the parameters of the HCY potential as a function of the thermodynamic states: one is based on the simultaneous fits of pressure and internal energy of the LJ system and the other uses the concept of collision frequency. The reasonable homogeneity of the results in both procedures of mapping makes that the HCY potential is a very good reference system, whose the proposed theoretical expressions can be used confidently to predict the thermodynamic properties of more realistic potentials
Modeling Aggregation Processes of Lennard-Jones particles Via Stochastic Networks
Forman, Yakir; Cameron, Maria
2017-07-01
We model an isothermal aggregation process of particles/atoms interacting according to the Lennard-Jones pair potential by mapping the energy landscapes of each cluster size N onto stochastic networks, computing transition probabilities from the network for an N-particle cluster to the one for N+1, and connecting these networks into a single joint network. The attachment rate is a control parameter. The resulting network representing the aggregation of up to 14 particles contains 6427 vertices. It is not only time-irreversible but also reducible. To analyze its transient dynamics, we introduce the sequence of the expected initial and pre-attachment distributions and compute them for a wide range of attachment rates and three values of temperature. As a result, we find the configurations most likely to be observed in the process of aggregation for each cluster size. We examine the attachment process and conduct a structural analysis of the sets of local energy minima for every cluster size. We show that both processes taking place in the network, attachment and relaxation, lead to the dominance of icosahedral packing in small (up to 14 atom) clusters.
Efficient Implementations of Molecular Dynamics Simulations for Lennard-Jones Systems
Watanabe, H.
2011-08-01
Efficient implementations of the classical molecular dynamics (MD) method for Lennard-Jones particle systems are considered. Not only general algorithms but also techniques that are efficient for some specific CPU architectures are also explained. A simple spatialdecomposition-based strategy is adopted for parallelization. By utilizing the developed code, benchmark simulations are performed on a HITACHI SR16000/J2 system consisting of IBM POWER6 processors which are 4.7 GHz at the National Institute for Fusion Science (NIFS) and an SGI Altix ICE 8400EX system consisting of Intel Xeon processors which are 2.93 GHz at the Institute for Solid State Physics (ISSP), the University of Tokyo. The parallelization efficiency of the largest run, consisting of 4.1 billion particles with 8192 MPI processes, is about 73% relative to that of the smallest run with 128 MPI processes at NIFS, and it is about 66% relative to that of the smallest run with 4 MPI processes at ISSP. The factors causing the parallel overhead are investigated. It is found that fluctuations of the execution time of each process degrade the parallel efficiency. These fluctuations may be due to the interference of the operating system, which is known as OS Jitter.
Pieprzyk, S.; Brańka, A. C.; Maćkowiak, Sz.; Heyes, D. M.
2018-03-01
The equation of state (EoS) of the Lennard-Jones fluid is calculated using a new set of molecular dynamics data which extends to higher temperature than in previous studies. The modified Benedict-Webb-Rubin (MBWR) equation, which goes up to ca. T ˜ 6, is reparametrized with new simulation data. A new analytic form for the EoS, which breaks the fluid range into two regions with different analytic forms and goes up to ca. T ≃ 35, is also proposed. The accuracy of the new formulas is at least as good as the MBWR fit and goes to much higher temperature allowing it to now encompass the Amagat line. The fitted formula extends into the high temperature range where the system can be well represented by inverse power potential scaling, which means that our specification of the equation of state covers the entire (ρ, T) plane. Accurate analytic fit formulas for the Boyle, Amagat, and inversion curves are presented. Parametrizations of the extrema loci of the isochoric, CV, and isobaric, CP, heat capacities are given. As found by others, a line maxima of CP terminates in the critical point region, and a line of minima of CP terminates on the freezing line. The line of maxima of CV terminates close to or at the critical point, and a line of minima of CV terminates to the right of the critical point. No evidence for a divergence in CV in the critical region is found.
A model-adaptivity method for the solution of Lennard-Jones based adhesive contact problems
Ben Dhia, Hachmi; Du, Shuimiao
2018-05-01
The surface micro-interaction model of Lennard-Jones (LJ) is used for adhesive contact problems (ACP). To address theoretical and numerical pitfalls of this model, a sequence of partitions of contact models is adaptively constructed to both extend and approximate the LJ model. It is formed by a combination of the LJ model with a sequence of shifted-Signorini (or, alternatively, -Linearized-LJ) models, indexed by a shift parameter field. For each model of this sequence, a weak formulation of the associated local ACP is developed. To track critical localized adhesive areas, a two-step strategy is developed: firstly, a macroscopic frictionless (as first approach) linear-elastic contact problem is solved once to detect contact separation zones. Secondly, at each shift-adaptive iteration, a micro-macro ACP is re-formulated and solved within the multiscale Arlequin framework, with significant reduction of computational costs. Comparison of our results with available analytical and numerical solutions shows the effectiveness of our global strategy.
Dodecagonal order in a two-dimensional Lennard-Jones system
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Leung, P.W.; Henley, C.L.; Chester, G.V.
1989-01-01
We investigate a two-dimensional Lennard-Jones mixture with the interaction parameters chosen so as to favor configurations where the large atoms form squares and equilateral triangles. Many such configurations are possible which by our choice of interactions are nearly degenerate in energy. It is hypothesized that a thermal equilibrium state with 12-fold orientational order exists. Several Monte Carlo simulations were performed to cool the system to a temperature approaching zero. The ordering process was studied by following the evolution of the configurations with temperature. The onset of ordering seemed to be very diffuse in space rather than nucleated at a point. The resulting configurations consist of squares and triangles, except for a few dislocations, and thus have perfect orientational order. We also characterized the deviation from ideal quasiperiodicity in terms of the ''phason strain''; this was analyzed both by fitting a linear relation between the physical space coordinates of the atoms and the corresponding ''perpendicular space'' coordinates, and also by calculating the diffraction peaks. The latter are shifted and broadened, relative to an ideal 12-fold diffraction pattern, as in real quasicrystals
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Garcia, N.
1978-01-01
The GR method for solving the scattering equations of atoms from a hard corrugated surface is applied on accelerated particles above a hard corrugated surface and a hard corrugated surface with an attractive well. The solutions are given for the Rayleigh hypothesis that under the range of corrugation presented in this paper leads to the exact ones. Threshold resonances are studied observing that the appearance and disappearance of beams must be for a general theory with vertical tangent. The structure of the Lennard-Jones resonances given for the model mentioned above. For the first time it is stressed that Lennard-Jones resonances are not observed in metal surfaces in general, and, accordingly, they are unobserved in compact metallic surfaces. This is correlated with the fact that diffraction has not been observed. Both facts are due to the very weak corrugation of the gas-metal interaction potential. According to our results, the Lennard-Jones resonances in metals present greater difficulties to be observed experimentally. It is also noted that the absence of diffraction in compact metal surfaces is because they are almost plane and not because of the Debye-Waller effect. Finally, the lifetimes of the atoms at the crystal surfaces are calculated. These are larger, the smaller the incident energy and the larger the corrugation. But the lifetimes are particularly large at resonance conditions (10 -11 s). (Auth.)
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Lee, Song Hi
2010-01-01
We presented a molecular dynamics (MD) simulation study of friction behavior between two very massive Brownian particles (BPs) oriented along the z axis with BP centers at -R 12 /2 and R 12 /2 in a Lennard-Jones solvent as a function of the inter-particle separation, R 12 . In order to fix the BPs in space an MD simulation method with the mass of the BP as 10 90 g/mol was employed in which the total momentum of the system was conserved. The cross friction coefficients of x- and y-components are nearly insensitive to R 12 but that of z-component varies with R 12 in good accord with the simple hydrodynamic approximation. On the other hand, the self-friction coefficients are estimated as a very small difference from the single particle friction coefficients, ξ 0 , at all inter-particle separations which agrees with the simple hydrodynamic approximation. Consequently ξ (-) xx is nearly independent of R 12 and equal to its asymptotic value of twice the single particle friction coefficient, and the other relative friction, ξ (-) zz , is in good agreement with the simple hydrodynamic approximation. Molecular theory of Brownian motion of a single heavy particle in a fluid had received a considerable attention in earlier years. After molecular dynamics (MD) simulation technique was utilized, this subject has been widely studied by a variety of MD simulation methods. The common issues here were about the long time behavior of the force and velocity autocorrelation functions, the system size dependent friction coefficient of a massive Brownian particle, and test of the Stokes-Einstein law
Flory-Huggins parameter χ, from binary mixtures of Lennard-Jones particles to block copolymer melts
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Chremos, Alexandros; Nikoubashman, Arash; Panagiotopoulos, Athanassios Z.
2014-01-01
In this contribution, we develop a coarse-graining methodology for mapping specific block copolymer systems to bead-spring particle-based models. We map the constituent Kuhn segments to Lennard-Jones particles, and establish a semi-empirical correlation between the experimentally determined Flory-Huggins parameter χ and the interaction of the model potential. For these purposes, we have performed an extensive set of isobaric–isothermal Monte Carlo simulations of binary mixtures of Lennard-Jones particles with the same size but with asymmetric energetic parameters. The phase behavior of these monomeric mixtures is then extended to chains with finite sizes through theoretical considerations. Such a top-down coarse-graining approach is important from a computational point of view, since many characteristic features of block copolymer systems are on time and length scales which are still inaccessible through fully atomistic simulations. We demonstrate the applicability of our method for generating parameters by reproducing the morphology diagram of a specific diblock copolymer, namely, poly(styrene-b-methyl methacrylate), which has been extensively studied in experiments
Flory-Huggins parameter χ, from binary mixtures of Lennard-Jones particles to block copolymer melts
Energy Technology Data Exchange (ETDEWEB)
Chremos, Alexandros, E-mail: achremos@imperial.ac.uk [Department of Chemical Engineering, Centre for Process Systems Engineering, Imperial College London, South Kensington Campus, London SW7 2AZ (United Kingdom); Nikoubashman, Arash, E-mail: arashn@princeton.edu; Panagiotopoulos, Athanassios Z. [Department of Chemical and Biological Engineering, Princeton University, Princeton, New Jersey 08544 (United States)
2014-02-07
In this contribution, we develop a coarse-graining methodology for mapping specific block copolymer systems to bead-spring particle-based models. We map the constituent Kuhn segments to Lennard-Jones particles, and establish a semi-empirical correlation between the experimentally determined Flory-Huggins parameter χ and the interaction of the model potential. For these purposes, we have performed an extensive set of isobaric–isothermal Monte Carlo simulations of binary mixtures of Lennard-Jones particles with the same size but with asymmetric energetic parameters. The phase behavior of these monomeric mixtures is then extended to chains with finite sizes through theoretical considerations. Such a top-down coarse-graining approach is important from a computational point of view, since many characteristic features of block copolymer systems are on time and length scales which are still inaccessible through fully atomistic simulations. We demonstrate the applicability of our method for generating parameters by reproducing the morphology diagram of a specific diblock copolymer, namely, poly(styrene-b-methyl methacrylate), which has been extensively studied in experiments.
Kinetic energy of solid and liquid para-hydrogen: a path integral Monte Carlo simulation
International Nuclear Information System (INIS)
Zoppi, M.; Neumann, M.
1992-01-01
The translational (center of mass) kinetic energy of solid and liquid para-hydrogen have been recently measured by means of Deep Inelastic Neutron Scattering. We have evaluated the same quantity, in similar thermodynamic conditions, by means of Path Integral Monte Carlo computer simulation, modelling the system as composed of a set of spherical molecules interacting through a pairwise additive Lennard-Jones potential. In spite of the crude approximations on the interaction potential, the agreement is excellent. The pressure was also computed by means of the same simulations. This quantity, compared with the equation of state for solid para-hydrogen given by Driessen and Silvera, gives an agreement of a lesser quality and a negative value for the liquid state. We attribute this discrepancy to the limitations of the Lennard-Jones potential. (orig.)
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Johnson, W.R.; Dzuba, V.A.; Safronova, U.I.; Safronova, M.S.
2004-01-01
A finite-field scaling method is applied to evaluate the Lennard-Jones interaction constant C 3 for alkali-metal atoms. The calculations are based on the relativistic single-double approximation in which single and double excitations of Dirac-Hartree-Fock wave functions are included to all orders in perturbation theory
Bazhenov, Alexiev M.; Heyes, David M.
1990-01-01
The thermodynamics, structure, and transport coefficients, as defined by the Green-Kubo integrals, of the one-dimensional Lennard-Jones fluid are evaluated for a wide range of state points by molecular dynamics computer simulation. These calculations are performed for the first time for thermal conductivity and the viscosity. We observe a transition from hard-rod behavior at low number density to harmonic-spring fluid behavior in the close-packed limit. The self-diffusion coefficient decays with increasing density to a finite limiting value. The thermal conductivity increases with density, tending to ∞ in the close-packed limit. The viscosity in contrast maximizes at intermediate density, tending to zero in the zero density and close-packed limits.
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Merabia, Samy; Termentzidis, Konstantinos
2012-01-01
We characterize the thermal Kapitza conductance between Lennard-Jones solids using non-equilibrium molecular dynamics simulations. We consider a series of perfect interfaces between mass-mismatched solids. We show that both the acoustic mismatch model (AMM) and the diffuse mismatch model (DMM) fail to predict the interfacial conductance even for large acoustic mismatched solids. This poor agreement may be explained by the use of equilibrium distributions of phonons in the expression of the conductance. On the other hand, we show that an extension of AMM taking into account the out-of-equilibrium phonon distribution on both sides of the interface leads to a good agreement with the simulation results, even for interfaces between almost similar materials. This opens the way to understand interfacial heat transport across real semi-conductors and dielectrics.
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Lin, T.; Bian, X.F.; Jiang, J.
2006-01-01
Two metallic bulk glasses, Cu 60 Zr 30 Ti 10 and Cu 47 Ti 33 Zr 11 Ni 8 Si 1 , with a diameter of 3 mm were prepared by copper mold casting method. Dilatometric measurement was carried out on the two glassy alloys to obtain information about the average nearest-neighbour distance r 0 and the effective depth of pair potential V 0 . By assuming a Lennard-Jones potential, r 0 and V 0 were calculated to be 0.28 nm and 0.16 eV for Cu 60 Zr 30 Ti 10 and 0.27 nm and 0.13 eV for Cu 47 Ti 33 Zr 11 Ni 8 Si 1 , respectively. It was found that the glassy alloy Cu 60 Zr 30 Ti 10 was more stable than Cu 47 Ti 33 Zr 11 Ni 8 Si 1 against heating from both experiment and calculation
International Nuclear Information System (INIS)
Garcia, N.
1976-01-01
This paper considers the effect of the attractive part of the interaction potential on the scattering of He atoms from a LiF(001) surface. We calculate, in particular, the Lennard-Jones resonances on the intensities and the phases of the scattered amplitudes, using a square well in the front of a hard corrugated surface model. We show that the amplitudes for incident energies smaller than the depth of the well are dominated by the resonances
Mirzaeinia, Ali; Feyzi, Farzaneh; Hashemianzadeh, Seyed Majid
2017-12-07
Simple and accurate expressions are presented for the equation of state (EOS) and absolute Helmholtz free energy of a system composed of simple atomic particles interacting through the repulsive Lennard-Jones potential model in the fluid and solid phases. The introduced EOS has 17 and 22 coefficients for fluid and solid phases, respectively, which are regressed to the Monte Carlo (MC) simulation data over the reduced temperature range of 0.6≤T * ≤6.0 and the packing fraction range of 0.1 ≤ η ≤ 0.72. The average absolute relative percent deviation in fitting the EOS parameters to the MC data is 0.06 and 0.14 for the fluid and solid phases, respectively. The thermodynamic integration method is used to calculate the free energy using the MC simulation results. The Helmholtz free energy of the ideal gas is employed as the reference state for the fluid phase. For the solid phase, the values of the free energy at the reduced density equivalent to the close-packed of a hard sphere are used as the reference state. To check the validity of the predicted values of the Helmholtz free energy, the Widom particle insertion method and the Einstein crystal technique of Frenkel and Ladd are employed. The results obtained from the MC simulation approaches are well agreed to the EOS results, which show that the proposed model can reliably be utilized in the framework of thermodynamic theories.
International Nuclear Information System (INIS)
Dowell, F.
1983-01-01
Two average-environment simple cubic lattice models: a refined model and a simple model, both having site-site (segmental) pair Lennard-Jones (LJ) interactions: for molecules composed of rigid cores having semiflexible tails are presented. The calculated values of the following properties at the nematic-isotropic transition for rigid rods of varying length are compared with relevant experimental data for PAA (p-azoxyanisole, or 4,4'-dimethoxyazoxybenzene): temperature, core orientational order parameter, nematic density and volume, relative density change, and relative entropy change. The temperature change as a function of volume change at constant order parameter is also discussed. In general, both LJ models give considerably better quantitative agreement with experiment, especially for the temperature and the relative density change, than do the earlier lattice models with hard repulsions, with or without constant segmental pair interaction energies. In most aspects, these LJ models give good quantitative agreement with experiment. These LJ models elucidate the importance of realistic intermolecular potentials, especially the role of soft repulsions, in describing an order-disorder transition between two condensed phases
International Nuclear Information System (INIS)
Van Zon, Ramses; Ashwin, S S; Cohen, E G D
2008-01-01
To describe short time (picosecond) and small scale (nanometre) transport in fluids, a Green's function approach was recently developed. This approach relies on an expansion of the distribution of single particle displacements around a Gaussian function, yielding an infinite series of correction terms. Applying a recent theorem (van Zon and Cohen 2006 J. Stat. Phys. 123 1–37) shows that for sufficiently small times the terms in this series become successively smaller, so that truncating the series near or at the Gaussian level might provide a good approximation. In this paper, we derive a theoretical estimate for the time scale at which truncating the series at or near the Gaussian level could be supposed to be accurate for equilibrium nanoscale systems. In order to numerically estimate this time scale, the coefficients for the first few terms in the series are determined in computer simulations for a Lennard-Jones (LJ) fluid, an isotopic LJ mixture and a suspension of a LJ-based model of nanoparticles in a LJ fluid. The results suggest that for LJ fluids an expansion around a Gaussian is accurate at time scales up to a picosecond, while for nanoparticles in suspension (a nanofluid), the characteristic time scale up to which the Gaussian is accurate becomes of the order of 5–10 ps. (invited article)
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Saeidi, Mohammadreza; Vaezzadeh, Majid; Badakhshan, Farzaneh
2011-01-01
Influence of DC electric field on carbon nanotube (CNT) growth in chemical vapor deposition is studied. Investigation of electric field effect in van der Waals interaction shows that increase in DC electric field raises the magnitude of attractive term of the Lennard-Jones potential. By using a theoretical model based on phonon vibrations of CNT on catalyst, it is shown that there is an optimum field for growth. Also it is observed that CNT under optimum electric field is longer than CNT in the absence of field. Finally, the relation between optimum DC electric field and type of catalyst is investigated and for some intervals of electric field, the best catalyst is introduced, which is very useful for experimental researches. -- Research highlights: → Influence of DC electric field on CNT growth in CVD. → Effect of electric field on van der Waals interaction between CNT and its catalyst. → Applying DC electric field increases attractive term of Lennard-Jonespotential. → There is an optimum DC field for CNT growth. → For catalyst with stronger van der Waals interaction, optimum field is smaller.
International Nuclear Information System (INIS)
Erpenbeck, J.J.
1987-01-01
We apply the so-called ''synthetic'' nonequilibrium molecular-dynamics method to the calculation of the self-diffusion constant of a Lennard-Jones fluid at a number density of 0.85/σ 3 and a temperature of 1.08 epsilon-c/k/sub B/ (where epsilon-c and σ are the energy and length parameters of the potential and k/sub B/ is the Boltzmann constant). By comparing with the Green-Kubo calculation for the same state of the system and for the same number of particles, N, we find the latter calculation to yield more precise values of the self-diffusion constant for a given number of molecular-dynamics time steps. Even at small values of the diffusion current, a nontrivial time is needed for the nonequilibrium calculation to reach the steady state. For larger values of the driving force, the steady-state flow appears to become unstable and evidence of a secondary flow pattern is presented. The presence of these instabilities acts as a limit to the range of the driving force for which the steady-state method can be applied. With increasing N the range of stable values of the diffusion current density decreases. For the Green-Kubo calculations, the N dependence of the self-diffusion constant is found to be anomalous for N = 108, with the 1/N dependence only exhibited for at least 500 particles. The nonequilibrium results, while approximately independent of N for 108 and 500 particles, are found to have a similar anomalous N dependence when we extend the calculations to 1372 particles, thereby bringing the Green-Kubo and nonequilibrium results into agreement in the large-system limit
Addendum to ''Density fluctuations in liquid rubidium''
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Haan, S.W.; Mountain, R.D.; Hsu, C.S.; Rahman, A.
1980-01-01
We performed molecular-dynamics simulations of liquid rubidium and the Lennard-Jones fluid at several densities and temperatures, and of a system whose pair potential is the repulsive core of the rubidium potential. In all cases, propagating density fluctuations occurred in the rubidiumlike systems at much shorter wavelengths than in the Lennard-Jones system. This indicates that the repulsive part of the pair potential is the dominant factor in determining the relaxation of short-wavelength density fluctuations
Vogelsang, R.; Hoheisel, C.
1987-02-01
Molecular-dynamics (MD) calculations are reported for three thermodynamic states of a Lennard-Jones fluid. Systems of 2048 particles and 105 integration steps were used. The transverse current autocorrelation function, Ct(k,t), has been determined for wave vectors of the range 0.5viscosities which showed a systematic behavior as a function of k. Extrapolation to the hydrodynamic region at k=0 gave shear viscosity coefficients in good agreement with direct Green-Kubo results obtained in previous work. The two-exponential model fit for the memory function proposed by other authors does not provide a reasonable description of the MD results, as the fit parameters show no systematic wave-vector dependence, although the Ct(k,t) functions are somewhat better fitted. Similarly, the semiempirical interpolation formula for the decay time based on the viscoelastic concept proposed by Akcasu and Daniels fails to reproduce the correct k dependence for the wavelength range investigated herein.
Molecular Simulation of the Vapor-Liquid Phase Behavior of Lennard-Jones Mixtures in Porous Solids
2006-09-01
sur la Catalyse, Centre National de la Recherche Scientifique, Group de Chimie Theorique, 2 Avenue Albert Einstein, 69626 Villeurbanne Cedex, France...and Group de Chimie Theorique, Ecole Normale Superieure de Lyon, 46 Allee d’Italie, 69364 Lyon, Cedex 07, France 14. ABSTRACT We present vapor...Scientifique, Group de Chimie Theorique, 2 Avenue Albert Einstein, 69626 Villeurbanne Cedex, France and Group de Chimie Theorique, Ecole Normale
Georgescu, Ionuţ; Mandelshtam, Vladimir A
2012-10-14
The theory of self-consistent phonons (SCP) was originally developed to address the anharmonic effects in condensed matter systems. The method seeks a harmonic, temperature-dependent Hamiltonian that provides the "best fit" for the physical Hamiltonian, the "best fit" being defined as the one that optimizes the Helmholtz free energy at a fixed temperature. The present developments provide a scalable O(N) unified framework that accounts for anharmonic effects in a many-body system, when it is probed by either thermal (ℏ → 0) or quantum fluctuations (T → 0). In these important limits, the solution of the nonlinear SCP equations can be reached in a manner that requires only the multiplication of 3N × 3N matrices, with no need of diagonalization. For short range potentials, such as Lennard-Jones, the Hessian, and other related matrices are highly sparse, so that the scaling of the matrix multiplications can be reduced from O(N(3)) to ~O(N). We investigate the role of quantum effects by continuously varying the de-Boer quantum delocalization parameter Λ and report the N-Λ (T = 0), and also the classical N-T (Λ = 0) phase diagrams for sizes up to N ~ 10(4). Our results demonstrate that the harmonic approximation becomes inadequate already for such weakly quantum systems as neon clusters, or for classical systems much below the melting temperatures.
Lennard-Jones fluids in two-dimensional nano-pores. Multi-phase coexistence and fluid structure
Yatsyshin, Petr; Savva, Nikos; Kalliadasis, Serafim
2014-03-01
We present a number of fundamental findings on the wetting behaviour of nano-pores. A popular model for fluid confinement is a one-dimensional (1D) slit pore formed by two parallel planar walls and it exhibits capillary condensation (CC): a first-order phase transition from vapour to capillary-liquid (Kelvin shift). Capping such a pore at one end by a third orthogonal wall forms a prototypical two-dimensional (2D) pore. We show that 2D pores possess a wetting temperature such that below this temperature CC remains of first order, above it becomes a continuous phase transition manifested by a slab of capillary-liquid filling the pore from the capping wall. Continuous CC exhibits hysteresis and can be preceded by a first-order capillary prewetting transition. Additionally, liquid drops can form in the corners of the 2D pore (remnant of 2D wedge prewetting). The three fluid phases, vapour, capillary-liquid slab and corner drops, can coexist at the pore triple point. Our model is based on the statistical mechanics of fluids in the density functional formulation. The fluid-fluid and fluid-substrate interactions are dispersive. We analyze in detail the microscopic fluid structure, isotherms and full phase diagrams. Our findings also suggest novel ways to control wetting of nano-pores. We are grateful to the European Research Council via Advanced Grant No. 247031 for support.
Oh, Inrok; Choi, Saehyun; Jung, YounJoon; Kim, Jun Soo
2015-08-28
Phase separation in a biological cell nucleus occurs in a heterogeneous environment filled with a high density of chromatins and thus it is inevitably influenced by interactions with chromatins. As a model system of nuclear body formation in a cell nucleus filled with chromatins, we simulate the phase separation of a low-density Lennard-Jones (LJ) fluid interacting with a long, condensed polymer chain. The influence of the density variation of LJ particles above and below the phase boundary and the role of attractive interactions between LJ particles and polymer segments are investigated at a fixed value of strong self-interaction between LJ particles. For a density of LJ particles above the phase boundary, phase separation occurs and a dense domain of LJ particles forms irrespective of interactions with the condensed polymer chain whereas its localization relative to the polymer chain is determined by the LJ-polymer attraction strength. Especially, in the case of moderately weak attractions, the domain forms separately from the polymer chain and subsequently associates with the polymer chain. When the density is below the phase boundary, however, the formation of a dense domain is possible only when the LJ-polymer attraction is strong enough, for which the domain grows in direct contact with the interacting polymer chain. In this work, different growth behaviors of LJ particles result from the differences in the density of LJ particles and in the LJ-polymer interaction, and this work suggests that the distinct formation of activity-dependent and activity-independent nuclear bodies (NBs) in a cell nucleus may originate from the differences in the concentrations of body-specific NB components and in their interaction with chromatins.
Gas Enrichment at Liquid-Wall Interfaces
Dammer, S.M.; Lohse, Detlef
2006-01-01
Molecular dynamics simulations of Lennard-Jones systems are performed to study the effects of dissolved gas on liquid-wall and liquid-gas interfaces. Gas enrichment at walls, which for hydrophobic walls can exceed more than 2 orders of magnitude when compared to the gas density in the bulk liquid,
Elastic properties of surfactant monolayers at liquid-liquid interfaces: A molecular dynamics study
DEFF Research Database (Denmark)
Laradji, Mohamed; Mouritsen, Ole G.
2000-01-01
Using a simple molecular model based on the Lennard-Jones potential, we systematically study the elastic properties of liquid-liquid interfaces containing surfactant molecules by means of extensive and large-scale molecular dynamics simulations. The main elastic constants of the interface, corres...
Growing correlation length on cooling below the onset of caging in a simulated glass-forming liquid
DEFF Research Database (Denmark)
Lačević, N.; Starr, F. W.; Schrøder, Thomas
2002-01-01
We present a calculation of a fourth-order, time-dependent density correlation function that measures higher-order spatiotemporal correlations of the density of a liquid. From molecular dynamics simulations of a glass-forming Lennard-Jones liquid, we find that the characteristic length scale...... of the dynamics of the liquid in the alpha-relaxation regime....
DEFF Research Database (Denmark)
Toxværd, Søren; Dyre, J. C.
2011-01-01
. Lett. 103, 170601 (2009);10.1103/PhysRevLett.103.170601 J. Chem. Phys. 134, 214503 (2011)10.1063/1.3592709] . We present simulations of the standard Lennard-Jones liquid at several condensed-fluid state points, including a fairly low density state and a very high density state, as well as simulations...
Dislocation-like Structures in a Simulated Liquid
DEFF Research Database (Denmark)
Cotterill, Rodney M J
1979-01-01
The free-volume distribution in a simulated Lennard-Jones liquid is heterogeneous. Chains of holes, appearing as segments rather than a continuous network, have lifetimes that are brief compared with the mean vibration period of the atoms. Larger isolated holes persist for longer times. If the ch......The free-volume distribution in a simulated Lennard-Jones liquid is heterogeneous. Chains of holes, appearing as segments rather than a continuous network, have lifetimes that are brief compared with the mean vibration period of the atoms. Larger isolated holes persist for longer times....... If the chains are interpreted as dislocation cores, the observed dislocation density is 1.0×1014 cm-2, but the actual density is probably higher....
Energy Technology Data Exchange (ETDEWEB)
Caplan, Matthew E.; Giri, Ashutosh; Hopkins, Patrick E., E-mail: phopkins@virginia.edu [Department of Mechanical and Aerospace Engineering, University of Virginia, Charlottesville, Virginia 22904 (United States)
2014-04-21
We develop an analytical model for the thermal boundary conductance between a solid and a liquid. By infusing recent developments in the phonon theory of liquid thermodynamics with diffuse mismatch theory, we derive a closed form model that can predict the effects of wetting on the thermal boundary conductance across an interface between a solid and a classical liquid. We account for the complete wetting (hydrophilicity), or lack thereof (hydrophobicity), of the liquid to the solid by considering varying contributions of transverse mode interactions between the solid and liquid interfacial layers; this transverse coupling relationship is determined with local density of states calculations from molecular dynamics simulations between Lennard-Jones solids and a liquids with different interfacial interaction energies. We present example calculations for the thermal boundary conductance between both hydrophobic and hydrophilic interfaces of Al/water and Au/water, which show excellent agreement with measured values reported by Ge et al. [Z. Ge, D. G. Cahill, and P. V. Braun, Phys. Rev. Lett. 96, 186101 (2006)]. Our model does not require any fitting parameters and is appropriate to model heat flow across any planar interface between a solid and a classical liquid.
Resolving dispersion and induction components for polarisable molecular simulations of ionic liquids
Pádua, Agílio A. H.
2017-05-01
One important development in interaction potential models, or atomistic force fields, for molecular simulation is the inclusion of explicit polarisation, which represents the induction effects of charged or polar molecules on polarisable electron clouds. Polarisation can be included through fluctuating charges, induced multipoles, or Drude dipoles. This work uses Drude dipoles and is focused on room-temperature ionic liquids, for which fixed-charge models predict too slow dynamics. The aim of this study is to devise a strategy to adapt existing non-polarisable force fields upon addition of polarisation, because induction was already contained to an extent, implicitly, due to parametrisation against empirical data. Therefore, a fraction of the van der Waals interaction energy should be subtracted so that the Lennard-Jones terms only account for dispersion and the Drude dipoles for induction. Symmetry-adapted perturbation theory is used to resolve the dispersion and induction terms in dimers and to calculate scaling factors to reduce the Lennard-Jones terms from the non-polarisable model. Simply adding Drude dipoles to an existing fixed-charge model already improves the prediction of transport properties, increasing diffusion coefficients, and lowering the viscosity. Scaling down the Lennard-Jones terms leads to still faster dynamics and densities that match experiment extremely well. The concept developed here improves the overall prediction of density and transport properties and can be adapted to other models and systems. In terms of microscopic structure of the ionic liquids, the inclusion of polarisation and the down-scaling of Lennard-Jones terms affect only slightly the ordering of the first shell of counterions, leading to small decreases in coordination numbers. Remarkably, the effect of polarisation is major beyond first neighbours, significantly weakening spatial correlations, a structural effect that is certainly related to the faster dynamics of
Properties of liquid clusters in large-scale molecular dynamics nucleation simulations
International Nuclear Information System (INIS)
Angélil, Raymond; Diemand, Jürg; Tanaka, Kyoko K.; Tanaka, Hidekazu
2014-01-01
We have performed large-scale Lennard-Jones molecular dynamics simulations of homogeneous vapor-to-liquid nucleation, with 10 9 atoms. This large number allows us to resolve extremely low nucleation rates, and also provides excellent statistics for cluster properties over a wide range of cluster sizes. The nucleation rates, cluster growth rates, and size distributions are presented in Diemand et al. [J. Chem. Phys. 139, 74309 (2013)], while this paper analyses the properties of the clusters. We explore the cluster temperatures, density profiles, potential energies, and shapes. A thorough understanding of the properties of the clusters is crucial to the formulation of nucleation models. Significant latent heat is retained by stable clusters, by as much as ΔkT = 0.1ε for clusters with size i = 100. We find that the clusters deviate remarkably from spherical—with ellipsoidal axis ratios for critical cluster sizes typically within b/c = 0.7 ± 0.05 and a/c = 0.5 ± 0.05. We examine cluster spin angular momentum, and find that it plays a negligible role in the cluster dynamics. The interfaces of large, stable clusters are thinner than planar equilibrium interfaces by 10%−30%. At the critical cluster size, the cluster central densities are between 5% and 30% lower than the bulk liquid expectations. These lower densities imply larger-than-expected surface areas, which increase the energy cost to form a surface, which lowers nucleation rates
Geysermans, P; Elyeznasni, N; Russier, V
2005-11-22
We present a study of the structure in the interface between two immiscible liquids by density-functional theory and molecular-dynamics calculations. The liquids are modeled by Lennard-Jones potentials, which achieve immiscibility by suppressing the attractive interaction between unlike particles. The density profiles of the liquids display oscillations only in a limited part of the simple liquid-phase diagram (rho,T). When approaching the liquid-vapor coexistence, a significant depletion appears while the layering behavior of the density profile vanishes. By analogy with the liquid-vapor interface and the analysis of the adsorption this behavior is suggested to be strongly related to the drying transition.
Communication: Simple liquids' high-density viscosity
Costigliola, Lorenzo; Pedersen, Ulf R.; Heyes, David M.; Schrøder, Thomas B.; Dyre, Jeppe C.
2018-02-01
This paper argues that the viscosity of simple fluids at densities above that of the triple point is a specific function of temperature relative to the freezing temperature at the density in question. The proposed viscosity expression, which is arrived at in part by reference to the isomorph theory of systems with hidden scale invariance, describes computer simulations of the Lennard-Jones system as well as argon and methane experimental data and simulation results for an effective-pair-potential model of liquid sodium.
Communication: Simple liquids' high-density viscosity.
Costigliola, Lorenzo; Pedersen, Ulf R; Heyes, David M; Schrøder, Thomas B; Dyre, Jeppe C
2018-02-28
This paper argues that the viscosity of simple fluids at densities above that of the triple point is a specific function of temperature relative to the freezing temperature at the density in question. The proposed viscosity expression, which is arrived at in part by reference to the isomorph theory of systems with hidden scale invariance, describes computer simulations of the Lennard-Jones system as well as argon and methane experimental data and simulation results for an effective-pair-potential model of liquid sodium.
Variation along liquid isomorphs of the driving force for crystallization
DEFF Research Database (Denmark)
Pedersen, Ulf Rørbæk; Adrjanowicz, Karolina; Niss, Kristine
2017-01-01
at a reference temperature. More general analysis allows interpretation of experimental data for molecular liquids such as dimethyl phthalate and indomethacin, and suggests that the isomorph scaling exponent γ in these cases is an increasing function of density, although this cannot be seen in measurements......We investigate the variation of the driving force for crystallization of a supercooled liquid along isomorphs, curves along which structure and dynamics are invariant. The variation is weak, and can be predicted accurately for the Lennard-Jones fluid using a recently developed formalism and data...
Feasibility of a single-parameter description of equilibrium viscous liquid dynamics
DEFF Research Database (Denmark)
Pedersen, Ulf Rørbæk; Christensen, Tage Emil; Schrøder, Thomas
2008-01-01
Molecular dynamics results for the dynamic Prigogine-Defay ratio are presented for two glass-forming liquids, thus evaluating the experimentally relevant quantity for testing whether metastable-equilibrium liquid dynamics is described by a single parameter to a good approximation. For the Kob......-Andersen binary Lennard-Jones mixture as well as for an asymmetric dumbbell model liquid, a single-parameter description works quite well. This is confirmed by time-domain results where it is found that energy and pressure fluctuations are strongly correlated on the alpha time scale in the constant...
Comparison of potentials for polymeric liquids
International Nuclear Information System (INIS)
Jung, Hae Young
2002-01-01
Many theories for polymeric liquids are based on the concepts of cell, hole, free volume of lattice etc. In this theories, van der Waals potential, Lennard-Jones 6-12 potential and their modified potentials are commonly used. In this work, Mie(p,6)potential was applied to the Continuous Lattice Fluid Theory (which extends the discrete lattices of Lattice Fluid Theory to classically continuous lattices) and Dee-Walsch's Cell Theory (which modifies Flory's Equation of State Theory). Both of them are known to be successful theories for polymeric liquids. Thus, PVT values changing with p (the exponent in the repulsion potential) were calculated and compared with experimental values. And, calculated values of Lattice Fluid theory, Flory's Equation of State Theory and Cho-Sanchez Theory using perturbation method were also compared. Through the calculated results, van der Waals potential, Lennard-Jones 6-12 potential and Mie(p,6) potential for polymeric liquids were compared with each other
Isomorphs in the phase diagram of a model liquid without inverse power law repulsion
DEFF Research Database (Denmark)
Veldhorst, Arnold Adriaan; Bøhling, Lasse; Dyre, J. C.
2012-01-01
scattering function are calculated. The results are shown to reflect a hidden scale invariance; despite its exponential repulsion the Buckingham potential is well approximated by an inverse power-law plus a linear term in the region of the first peak of the radial distribution function. As a consequence...... the dynamics of the viscous Buckingham liquid is mimicked by a corresponding model with purely repulsive inverse-power-law interactions. The results presented here closely resemble earlier results for Lennard-Jones type liquids, demonstrating that the existence of strong correlations and isomorphs does...... not depend critically on the mathematical form of the repulsion being an inverse power law....
Estimating the density-scaling exponent of a monatomic liquid from its pair potential
DEFF Research Database (Denmark)
Bøhling, Lasse; Bailey, Nicholas; Schrøder, Thomas
2014-01-01
This paper investigates two conjectures for calculating the density dependence of the density-scaling exponent γ of a single-component, pair-potential liquid with strong virial potential-energy correlations. The first conjecture gives an analytical expression for γ directly in terms of the pair...... potential. The second conjecture is a refined version of this involving the most likely nearest-neighbor distance determined from the pair-correlation function. The conjectures are tested by simulations of three systems, one of which is the standard Lennard-Jones liquid. While both expressions give...
Role of attractive forces in determining the equilibrium structure and dynamics of simple liquids
DEFF Research Database (Denmark)
Toxværd, Søren
2015-01-01
Molecular Dynamics simulations of a Lennard-Jones system with different range of attraction show that the attractive forces modify the radial distribution of the particles. For condensed liquids only, the forces within the the first coordination shell (FCS) are important, but for gases and moderate...... condensed fluids, even the attractive forces outside the FCS play a role. The changes in the distribution caused by neglecting the attractive forces, lead to a too high pressure. The weak long-range attractions damp the dynamics and the diffusion of the particles in gas-, super critical fluid- and in liquid...
Nasrabad, Afshin Eskandari; Laghaei, Rozita; Eu, Byung Chan
2005-04-28
In previous work on the density fluctuation theory of transport coefficients of liquids, it was necessary to use empirical self-diffusion coefficients to calculate the transport coefficients (e.g., shear viscosity of carbon dioxide). In this work, the necessity of empirical input of the self-diffusion coefficients in the calculation of shear viscosity is removed, and the theory is thus made a self-contained molecular theory of transport coefficients of liquids, albeit it contains an empirical parameter in the subcritical regime. The required self-diffusion coefficients of liquid carbon dioxide are calculated by using the modified free volume theory for which the generic van der Waals equation of state and Monte Carlo simulations are combined to accurately compute the mean free volume by means of statistical mechanics. They have been computed as a function of density along four different isotherms and isobars. A Lennard-Jones site-site interaction potential was used to model the molecular carbon dioxide interaction. The density and temperature dependence of the theoretical self-diffusion coefficients are shown to be in excellent agreement with experimental data when the minimum critical free volume is identified with the molecular volume. The self-diffusion coefficients thus computed are then used to compute the density and temperature dependence of the shear viscosity of liquid carbon dioxide by employing the density fluctuation theory formula for shear viscosity as reported in an earlier paper (J. Chem. Phys. 2000, 112, 7118). The theoretical shear viscosity is shown to be robust and yields excellent density and temperature dependence for carbon dioxide. The pair correlation function appearing in the theory has been computed by Monte Carlo simulations.
The thermodynamic properties of normal liquid helium 3
Modarres, M.; Moshfegh, H. R.
2009-09-01
The thermodynamic properties of normal liquid helium 3 are calculated by using the lowest order constrained variational (LOCV) method. The Landau Fermi liquid model and Fermi-Dirac distribution function are considered as our statistical model for the uncorrelated quantum fluid picture and the Lennard-Jones and Aziz potentials are used in our truncated cluster expansion (LOCV) to calculate the correlated energy. The single particle energy is treated variationally through an effective mass. The free energy, pressure, entropy, chemical potential and liquid phase diagram as well as the helium 3 specific heat are evaluated, discussed and compared with the corresponding available experimental data. It is found that the critical temperature for the existence of the pure gas phase is about 4.90 K (4.45 K), which is higher than the experimental prediction of 3.3 K, and the helium 3 flashing temperature is around 0.61 K (0.50 K) for the Lennard-Jones (Aziz) potential.
Evolution of short range order in Ar: Liquid to glass and solid transitions-A computational study
Shor, Stanislav; Yahel, Eyal; Makov, Guy
2018-04-01
The evolution of the short range order (SRO) as a function of temperature in a Lennard-Jones model liquid with Ar parameters was determined and juxtaposed with thermodynamic and kinetic properties obtained as the liquid was cooled (heated) and transformed between crystalline solid or glassy states and an undercooled liquid. The Lennard-Jones system was studied by non-equilibrium molecular dynamics simulations of large supercells (approximately 20000 atoms) rapidly cooled or heated at selected quenching rates and at constant pressure. The liquid to solid transition was identified by discontinuities in the atomic volume and molar enthalpy; the glass transition temperature range was identified from the temperature dependence of the self-diffusion. The SRO was studied within the quasi-crystalline model (QCM) framework and compared with the Steinhardt bond order parameters. Within the QCM it was found that the SRO evolves from a bcc-like order in the liquid through a bct-like short range order (c/a=1.2) in the supercooled liquid which persists into the glass and finally to a fcc-like ordering in the crystalline solid. The variation of the SRO that results from the QCM compares well with that obtained with Steinhardt's bond order parameters. The hypothesis of icosahedral order in liquids and glasses is not supported by our results.
Solvation in atomic liquids: connection between Gaussian field theory and density functional theory
Directory of Open Access Journals (Sweden)
V. Sergiievskyi
2017-12-01
Full Text Available For the problem of molecular solvation, formulated as a liquid submitted to the external potential field created by a molecular solute of arbitrary shape dissolved in that solvent, we draw a connection between the Gaussian field theory derived by David Chandler [Phys. Rev. E, 1993, 48, 2898] and classical density functional theory. We show that Chandler's results concerning the solvation of a hard core of arbitrary shape can be recovered by either minimising a linearised HNC functional using an auxiliary Lagrange multiplier field to impose a vanishing density inside the core, or by minimising this functional directly outside the core — indeed a simpler procedure. Those equivalent approaches are compared to two other variants of DFT, either in the HNC, or partially linearised HNC approximation, for the solvation of a Lennard-Jones solute of increasing size in a Lennard-Jones solvent. Compared to Monte-Carlo simulations, all those theories give acceptable results for the inhomogeneous solvent structure, but are completely out-of-range for the solvation free-energies. This can be fixed in DFT by adding a hard-sphere bridge correction to the HNC functional.
Energy Technology Data Exchange (ETDEWEB)
Geysermans, P.; Pontikis, V. [Centre National de la Recherche Scientifique (CNRS), 94 - Vitry-sur-Seine (France). Centre d' Etudes de Chimie Metallurgique
2002-09-01
The atomic structure of the solid-liquid heterophase interface was investigated by using molecular dynamics. Two kinds of systems were studied; the first one was crystalline copper with (100) and (111) surface terminations in contact with liquid aluminium, while in the second one the interface was modelled by two systems in contact made of Lennard-Jones particles with different size ({sigma}) and energy ({epsilon}) parameters. We found that at the interface the liquid was layered whatever the crystallographic orientation of the surface. The layering of the liquid is still preserved when the ratio of particles sites ({chi}={sigma}{sub 1}/{sigma}{sub 2}) changes while an epitaxial relationship is always found between the crystal and the first liquid layer. The average density of the latter is closely related to the {chi} value. (authors)
The structure of the solid-liquid interface: atomic size effect
International Nuclear Information System (INIS)
Geysermans, P.; Pontikis, V.
2002-01-01
The atomic structure of the solid-liquid heterophase interface was investigated by using molecular dynamics. Two kinds of systems were studied; the first one was crystalline copper with (100) and (111) surface terminations in contact with liquid aluminium, while in the second one the interface was modelled by two systems in contact made of Lennard-Jones particles with different size (σ) and energy (ε) parameters. We found that at the interface the liquid was layered whatever the crystallographic orientation of the surface. The layering of the liquid is still preserved when the ratio of particles sites (χ=σ 1 /σ 2 ) changes while an epitaxial relationship is always found between the crystal and the first liquid layer. The average density of the latter is closely related to the χ value. (authors)
Isoviscosity lines and the liquid-glass transition in simple liquids.
Fomin, Yu D; Brazhkin, V V; Ryzhov, V N
2012-07-01
This article presents the study of the generic behavior of viscosity of liquids based on some simple theoretical models, the soft-spheres and Lennard-Jones systems. The use of these simple models allows us to investigate in detail the viscosity behavior in a wide range of temperatures and pressures including the high-temperature-high-pressure limits. Based on the simulation results, we discuss the shape of isoviscosity lines and analyze the glass transition at high temperatures and high pressures. Despite the fact that the viscosity drastically increases in the limit of high temperatures and high pressures along the melting line, the relaxation time rapidly decreases in this region, and the system becomes further from the glass transition.
New theories for smectic and nematic liquid crystalline polymers
International Nuclear Information System (INIS)
Dowell, F.
1987-01-01
A summary of results from new statistical-physics theories for both backbone and side-chain liquid crystalline polymers (LCPs) and for mixtures with LCPs is presented. Thermodynamic and molecular ordering properties (including odd-even effects) have been calculated as a function of pressure, density, temperature, and molecule chemical structures (including degree of polymerization and the following properties of the chemical structures of the repeat units: lengths and shapes, intra-chain rotation energies, dipole moments, site-site polarizabilities and Lennard-Jones potentials, etc.) in nematic and multiple smectic-A LC phases and in the isotropic liquid phase. These theories can also be applied to combined LCPs. Since these theories have no ad hoc or arbitrarily adjustable parameters, these theories have been used to design new LCPs and new solvents and to predict and explain properties
Sub- and super-Maxwellian evaporation of simple gases from liquid water
International Nuclear Information System (INIS)
Kann, Z. R.; Skinner, J. L.
2016-01-01
Non-Maxwellian evaporation of light atoms and molecules (particles) such as He and H 2 from liquids has been observed experimentally. In this work, we use simulations to study systematically the evaporation of Lennard-Jones particles from liquid water. We find instances of sub- and super-Maxwellian evaporation, depending on the mass of the particle and the particle-water interaction strength. The observed trends are in qualitative agreement with experiment. We interpret these trends in terms of the potential of mean force and the effectiveness and frequency of collisions during the evaporation process. The angular distribution of evaporating particles is also analyzed, and it is shown that trends in the energy from velocity components tangential and normal to the liquid surface must be understood separately in order to interpret properly the angular distributions.
Sub- and super-Maxwellian evaporation of simple gases from liquid water
Energy Technology Data Exchange (ETDEWEB)
Kann, Z. R.; Skinner, J. L., E-mail: skinner@chem.wisc.edu [Theoretical Chemistry Institute and Department of Chemistry, University of Wisconsin, Madison, Wisconsin 53706 (United States)
2016-04-21
Non-Maxwellian evaporation of light atoms and molecules (particles) such as He and H{sub 2} from liquids has been observed experimentally. In this work, we use simulations to study systematically the evaporation of Lennard-Jones particles from liquid water. We find instances of sub- and super-Maxwellian evaporation, depending on the mass of the particle and the particle-water interaction strength. The observed trends are in qualitative agreement with experiment. We interpret these trends in terms of the potential of mean force and the effectiveness and frequency of collisions during the evaporation process. The angular distribution of evaporating particles is also analyzed, and it is shown that trends in the energy from velocity components tangential and normal to the liquid surface must be understood separately in order to interpret properly the angular distributions.
International Nuclear Information System (INIS)
Dowell, F.
1987-01-01
A summary of predictions and explanations from statistical-physics theories for both backbone and side-chain liquid crystalline polymers (LCPs) and for mixtures with backbone LCPs are presented. Trends in the thermodynamic and molecular ordering properties have been calculated as a function of pressure, density, temperature, and molecule chemical structures (including degree of polymerization and the following properties of the chemical structures of the repeat units: lengths and shapes, intra-chain rotation energies, dipole moments, site-site polarizabilities and Lennard-Jones potentials, etc.) in nematic and multiple smectic-A LC phases and in the isotropic liquid phase. The theoretical results are found to be in good agreement with existing experimental data. These theories can also be applied to combined LCPs. Since these theories have no ad hoc or arbitrarily adjustable parameters, these theories can be used to design new LCPs and new solvents as well as to predict and explain properties. 27 refs., 4 tabs
A free energy study of the liquid-liquid phase transition of the Jagla ...
Indian Academy of Sciences (India)
Appendix” preliminary free energy surface calculations for select parameterizations of the generalized family of Jagla potentials spanning from the original (anomalous,water-like) Jagla model to the Lennard-Jones model. These calculations ...
Probing heterogeneous dynamics from spatial density correlation in glass-forming liquids.
Li, Yan-Wei; Zhu, You-Liang; Sun, Zhao-Yan
2016-12-01
We numerically investigate the connection between spatial density correlation and dynamical heterogeneity in glass-forming liquids. We demonstrate that the cluster size defined by the spatial aggregation of densely packed particles (DPPs) can better capture the difference between the dynamics of the Lennard-Jones glass model and the Weeks-Chandler-Andersen truncation model than the commonly used pair correlation functions. More interestingly, we compare the mobility of DPPs and loosely packed particles, and we find that high local density correlates well with slow dynamics in systems with relatively hard repulsive interactions but links to mobile ones in the system with soft repulsive interactions at one relaxation time scale. Our results show clear evidence that the above model dependence behavior stems from the hopping motion of DPPs at the end of the caging stage due to the compressive nature of soft repulsive spheres, which activates the dynamics of DPPs in the α relaxation stage.
A Four-Site Molecular Model for Simulations of Liquid Methanol and Water-Methanol Mixtures: MeOH-4P.
Martínez-Jiménez, Manuel; Saint-Martin, Humberto
2018-04-17
In this work, we present a new four-site potential for methanol, MeOH-4P, fitted to reproduce the dielectric constant ε, the surface tension γ s , and the liquid density ρ of the pure liquid at T = 298.15 K and p = 1 bar. The partial charges on each site were taken from the OPLS/2016 model with the only difference of putting the negative charge on the fourth site ( M) instead of on the O atom, as done in four-site water models. The original Lennard-Jones (LJ) parameters of OPLS/2016 for the methyl moiety (Me) were modified for the fitting of ρ and γ s , whereas the parameters of the TIP4P-FB water model were used for the O atom without change. Taking into account the energetic cost of the enhanced dipole relative to the isolated molecule, the results from simulations with this model showed good agreement with experiments for ρ, α p , κ T , C p , and Δ H v- l . Also, the temperature dependence of γ s and ε is satisfactory in the interval between 260 and 360 K, and the critical point description is similar to that of OPLS/2016. It is shown that orientational correlations, described by the Kirkwood factor G k , play a prominent role in the appropriate description of dielectric constants in existing models; unfortunately, the enhancement of the dipole moment produced a low diffusion coefficient D MeOH ; thus, a compromise was required between a good reproduction of ε and an acceptable D MeOH . The use of a fourth site resulted in a significant improvement for water-methanol mixtures described with TIP4P-FB and MeOH-4P, respectively, but required the modification of the LJ geometric combination rule to allow a good description of the methanol molar-fraction dependence of ρ, ε, and methanol (water) diffusion coefficients D MeOH ( D H 2 O ) and excess volume of mixing Δ V mix in the entire range of composition. The resulting free energy of hydration Δ G hyd shows excellent agreement with experiments in the interval between 280 and 360 K.
Computer simulation of liquid crystals
International Nuclear Information System (INIS)
McBride, C.
1999-01-01
Molecular dynamics simulation performed on modern computer workstations provides a powerful tool for the investigation of the static and dynamic characteristics of liquid crystal phases. In this thesis molecular dynamics computer simulations have been performed for two model systems. Simulations of 4,4'-di-n-pentyl-bibicyclo[2.2.2]octane demonstrate the growth of a structurally ordered phase directly from an isotropic fluid. This is the first time that this has been achieved for an atomistic model. The results demonstrate a strong coupling between orientational ordering and molecular shape, but indicate that the coupling between molecular conformational changes and molecular reorientation is relatively weak. Simulations have also been performed for a hybrid Gay-Berne/Lennard-Jones model resulting in thermodynamically stable nematic and smectic phases. Frank elastic constants have been calculated for the nematic phase formed by the hybrid model through analysis of the fluctuations of the nematic director, giving results comparable with those found experimentally. Work presented in this thesis also describes the parameterization of the torsional potential of a fragment of a dimethyl siloxane polymer chain, disiloxane diol (HOMe 2 Si) 2 O, using ab initio quantum mechanical calculations. (author)
An EQT-based cDFT approach for a confined Lennard-Jones fluid mixture
Energy Technology Data Exchange (ETDEWEB)
Motevaselian, M. H.; Mashayak, S. Y.; Aluru, N. R., E-mail: aluru@illinois.edu [Department of Mechanical Science and Engineering, Beckman Institute for Advanced Science and Technology, University of Illinois at Urbana-Champaign, Urbana, Illinois 61801 (United States)
2015-09-28
Empirical potential-based quasi-continuum theory (EQT) provides a route to incorporate atomistic detail into continuum framework such as the Nernst-Planck equation. EQT can also be used to construct a grand potential functional for classical density functional theory (cDFT). The combination of EQT and cDFT provides a simple and fast approach to predict the inhomogeneous density, potential profiles, and thermodynamic properties of confined fluids. We extend the EQT-cDFT approach to confined fluid mixtures and demonstrate it by simulating a mixture of methane and hydrogen inside slit-like channels of graphene. We show that the EQT-cDFT predictions for the structure of the confined fluid mixture compare well with the molecular dynamics simulation results. In addition, our results show that graphene slit nanopores exhibit a selective adsorption of methane over hydrogen.
Fusion process of Lennard-Jones clusters: global minima and magic numbers formation
DEFF Research Database (Denmark)
Solov'yov, Ilia; Solov'yov, Andrey V.; Greiner, Walter
2004-01-01
We present a new theoretical framework for modeling the fusion process of Lennard–Jones (LJ) clusters. Starting from the initial tetrahedral cluster configuration, adding new atoms to the system and absorbing its energy at each step, we find cluster growing paths up to the cluster size of 150 atoms...
Efficient Implementations of Molecular Dynamics Simulations for Lennard-Jones Systems
Watanabe, H.; Suzuki, M.; Ito, N.
2011-01-01
simple spatialdecomposition-based strategy is adopted for parallelization. By utilizing the developed code, benchmark simulations are performed on a HITACHI SR16000/J2 system consisting of IBM POWER6 processors which are 4.7 GHz at the National Institute
Interaction forces between nanoparticles in Lennard-Jones (L-J) solvents
International Nuclear Information System (INIS)
Sinha, Indrajit; Mukherjee, Ashim K
2014-01-01
Molecular simulations, such as Monte Carlo (MC) and molecular dynamics (MD) have been recently used for understanding the forces between colloidal nanoparticles that determine the dispersion and stability of nanoparticle suspensions. Herein we review the current status of research in the area of nanoparticles immersed in L-J solvents. The first study by Shinto et al. used large smooth spheres to depict nanoparticles in L-J and soft sphere solvents. The nanoparticles were held fixed at a particular interparticle distance and only the solvents were allowed to equilibrate. Both Van-der-waals and solvation forces were computed at different but fixed interparticle separation. Later Qin and Fitchthorn improved on this model by considering the nanoparticles as collection of molecules, thus taking into the account the effect of surface roughness of nanoparticles. Although the inter particle distance was fixed, the rotation of such nanoparticles with respect to each other was also investigated. Recently, in keeping with the experimental situation, we modified this model by allowing the nanoparticles to move and rotate freely. Solvophilic, neutral and solvophobic interactions between the solvent atoms and those that make up the nanoparticles were modelled. While neutral and solvophobic nanoparticles coalesce even at intermediate distances, solvophilic nanoparticles are more stable in solution due to the formation of a solvent shield
Molecular dynamics calculation of half-lives for thermal decay of Lennard-Jones clusters
International Nuclear Information System (INIS)
Smith, R.W.
1991-01-01
Molecular dynamics has been used with a Lenard-Jones (6-12) potential in order to study the decay behavior of neutral Argon clusters containing between 12 and 14 atoms. The clusters were heated to temperatures well above their melting points and then tracked in time via molecular dynamics until evaporation of one or more atoms was observed. In each simulation, the mode of evaporation, energy released during evaporation, and cluster lifetime were recorded. Results from roughly 2000 simulation histories were combined in order to compute statistically significant values of cluster half-lives and decay energies. It was found that cluster half-life decreases with increasing energy and that for a given value of excess energy (defined as E=(E tot -E gnd )/n), the 13 atom cluster is more stable against decay than clusters containing either 12 or 14 atoms. The dominant decay mechanism for all clusters was determined to be single atom emission. (orig.)
Single-site Lennard-Jones models via polynomial chaos surrogates of Monte Carlo molecular simulation
Kadoura, Ahmad Salim; Siripatana, Adil; Sun, Shuyu; Knio, Omar; Hoteit, Ibrahim
2016-01-01
In this work, two Polynomial Chaos (PC) surrogates were generated to reproduce Monte Carlo (MC) molecular simulation results of the canonical (single-phase) and the NVT-Gibbs (two-phase) ensembles for a system of normalized structureless Lennard
Energy Technology Data Exchange (ETDEWEB)
Miranda, Daniel F.; Urata, Chihiro; Masheder, Benjamin; Dunderdale, Gary J.; Hozumi, Atsushi, E-mail: a.hozumi@aist.go.jp [National Institute of Advanced Industrial Science and Technology (AIST), 2266-98, Anagahora, Shimo-Shidami, Moriyama-ku, Nagoya, Aichi 463-8560 (Japan); Yagihashi, Makoto [Nagoya Municipal Industrial Research Institute, Rokuban, Atsuta-ku, Nagoya 456-0058 (Japan)
2014-05-01
A fluorinated and hydrophobic ionic liquid (IL), 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl) imide, effectively served as an advantageous lubricating liquid for the preparation of physically and chemically stable omniphobic surfaces based on slippery liquid-infused porous surfaces. Here, we used particulate microstructures as supports, prepared by the chemical vapor deposition of 1,3,5,7-tetramethylcyclotetrasiloxane and subsequent surface modification with (3-aminopropyl)triethoxysilane. Confirmed by SEM and contact angle measurements, the resulting IL-infused microtextured surfaces are smooth and not only water but also various low surface tension liquids can easily slide off at low substrate tilt angles of <5°, even after exposure to high temperature, vacuum, and UV irradiation.
Directory of Open Access Journals (Sweden)
Daniel F. Miranda
2014-05-01
Full Text Available A fluorinated and hydrophobic ionic liquid (IL, 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl imide, effectively served as an advantageous lubricating liquid for the preparation of physically and chemically stable omniphobic surfaces based on slippery liquid-infused porous surfaces. Here, we used particulate microstructures as supports, prepared by the chemical vapor deposition of 1,3,5,7-tetramethylcyclotetrasiloxane and subsequent surface modification with (3-aminopropyltriethoxysilane. Confirmed by SEM and contact angle measurements, the resulting IL-infused microtextured surfaces are smooth and not only water but also various low surface tension liquids can easily slide off at low substrate tilt angles of <5°, even after exposure to high temperature, vacuum, and UV irradiation.
Fragmentation of suddenly heated liquids in ICF reactors. Revision 1
International Nuclear Information System (INIS)
Blink, J.A.; Hoover, W.G.
1985-01-01
Fragmentation of free liquids in Inertial Confinement Fusion reactors could determine the upper bound on reactor pulse rate because increased surface area will enhance the cooling and condensation of coolant ablated by the fusion x rays. Relaxation from the suddenly (neutron) heated state will move a liquid into the negative pressure region under the liquid-vapor P-V dome. The resulting expansion in a diverging geometry will hydrodynamically force the liquid to fragment, with vapor then forming from the new surfaces to fill the cavities. An energy minimization model is used to determine the fragment size that produces the least amount of non-fragment-center-of-mass energy; i.e., the sum of the surface and dilational kinetic energies. This model predicts fragmentation dependence on original system size and amount of isochoric heating as well as liquid density, Grueneisen parameter, surface tension, and sound speed. A two dimensional molecular dynamics code was developed to test the model at a microscopic scale for the Lennard-Jones fluid with its two adjustable constants chosen to represent lithium
Excellent corrosion resistance of 18Cr-20Ni-5Si steel in liquid Pb-Bi
International Nuclear Information System (INIS)
Kurata, Y.; Futakawa, M.
2004-01-01
The corrosion properties of three austenitic steels with different Si contents were studied under oxygen-saturated liquid Pb-Bi condition for 3000 h. The three austenitic steels did not exhibit appreciable dissolution of Ni and Cr at 450 deg. C. At 550 deg. C, the thick ferrite layer produced by dissolution of Ni and Cr was found in JPCA and 316SS with low Si contents while the protective oxide film composed of Si and O was formed on 18Cr-20Ni-5Si steel and prevented dissolution of Ni and Cr
Fasoula, S; Zisi, Ch; Gika, H; Pappa-Louisi, A; Nikitas, P
2015-05-22
A package of Excel VBA macros have been developed for modeling multilinear gradient retention data obtained in single or double gradient elution mode by changing organic modifier(s) content and/or eluent pH. For this purpose, ten chromatographic models were used and four methods were adopted for their application. The methods were based on (a) the analytical expression of the retention time, provided that this expression is available, (b) the retention times estimated using the Nikitas-Pappa approach, (c) the stepwise approximation, and (d) a simple numerical approximation involving the trapezoid rule for integration of the fundamental equation for gradient elution. For all these methods, Excel VBA macros have been written and implemented using two different platforms; the fitting and the optimization platform. The fitting platform calculates not only the adjustable parameters of the chromatographic models, but also the significance of these parameters and furthermore predicts the analyte elution times. The optimization platform determines the gradient conditions that lead to the optimum separation of a mixture of analytes by using the Solver evolutionary mode, provided that proper constraints are set in order to obtain the optimum gradient profile in the minimum gradient time. The performance of the two platforms was tested using experimental and artificial data. It was found that using the proposed spreadsheets, fitting, prediction, and optimization can be performed easily and effectively under all conditions. Overall, the best performance is exhibited by the analytical and Nikitas-Pappa's methods, although the former cannot be used under all circumstances. Copyright © 2015 Elsevier B.V. All rights reserved.
Interfacial layering and capillary roughness in immiscible liquids.
Geysermans, P; Pontikis, V
2010-08-21
The capillary roughness and the atomic density profiles of extended interfaces between immiscible liquids are determined as a function of the interface area by using molecular dynamics and Lennard-Jones (12-6) potentials. We found that with increasing area, the interface roughness diverges logarithmically, thus fitting the theoretical mean-field prediction. In systems small enough for the interfacial roughness not to blur the structural details, atomic density profiles across the fluid interface are layered with correlation length in the range of molecular correlations in liquids. On increasing the system size, the amplitude of the thermally excited position fluctuations of the interface increases, thus causing layering to rapidly vanish, if density profiles are computed without special care. In this work, we present and validate a simple method, operating in the direct space, for extracting from molecular dynamics trajectories the "intrinsic" structure of a fluid interface that is the local density profile of the interface cleaned from capillary wave effects. Estimated values of interfacial properties such as the tension, the intrinsic width, and the lower wavelength limit of position fluctuations are in agreement with results collected from the literature.
Pair Potential That Reproduces the Shape of Isochrones in Molecular Liquids
DEFF Research Database (Denmark)
Veldhorst, Arno; Schrøder, Thomas; Dyre, Jeppe C.
2016-01-01
-dependent function of density, h(ρ), which for real liquids is well approximated by a power law, ργ. However, in simulations, a power law is not adequate when density changes are large; typical models, such as Lennard-Jones liquids, show that γ(ρ) ≡ d ln h(ρ)/d ln ρ is a decreasing function of density. This article...... presents results from computer simulations using a new pair potential that diverges at a nonzero distance and can be tuned to give a more realistic shape of γ(ρ). Our results indicate that the finite size of molecules is an important factor to take into account when modeling liquids over a large density......Many liquids have curves (isomorphs) in their phase diagrams along which structure, dynamics, and some thermodynamic quantities are invariant in reduced units. A substantial part of their phase diagrams is thus effectively one dimensional. The shapes of these isomorphs are described by a material...
Gujar, R B; Ansari, S A; Verboom, W; Mohapatra, P K
2016-05-27
Extraction chromatography resins, prepared by impregnating two multi-podant diglycolamide ligands, viz. diglycolamide-functionalized calix[4]arene (C4DGA) and tripodal diglycolamide (T-DGA) dissolved in the room temperature ionic liquid 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)amide (RTIL: C4mimTf2N) on Chromosorb-W (an inert solid support), gave excellent results for the removal of trivalent actinides from acidic waste solutions. Distribution coefficient measurements on several metal ions showed selective sorption of Am(III) over hexavalent uranyl ions and other fission product elements such as strontium and cesium. The sorbed metal ions could be efficiently desorbed with a complexing solution containing guanidine carbonate and EDTA buffer. The sorption of Am(III) on both resins followed pseudo-second order rate kinetics with rate constants of 1.37×10(-6) and 6.88×10(-7)g/cpmmin for T-DGA and C4DGA resins, respectively. The metal sorption on both resins indicated the Langmuir monolayer chemisorption phenomenon with Eu(III) sorption capacities of 4.83±0.21 and 0.52±0.05mg per g of T-DGA and C4DGA resins, respectively. The results of column studies show that these resins are of interest for a possible application for the recovery of hazardous trivalent actinides from dilute aqueous solutions. Copyright © 2016 Elsevier B.V. All rights reserved.
Capozza, R.; Vanossi, A.; Benassi, A.; Tosatti, E.
2015-02-01
Electrical charging of parallel plates confining a model ionic liquid down to nanoscale distances yields a variety of charge-induced changes in the structural features of the confined film. That includes even-odd switching of the structural layering and charging-induced solidification and melting, with important changes of local ordering between and within layers, and of squeezout behavior. By means of molecular dynamics simulations, we explore this variety of phenomena in the simplest charged Lennard-Jones coarse-grained model including or excluding the effect a neutral tail giving an anisotropic shape to one of the model ions. Using these models and open conditions permitting the flow of ions in and out of the interplate gap, we simulate the liquid squeezout to obtain the distance dependent structure and forces between the plates during their adiabatic approach under load. Simulations at fixed applied force illustrate an effective electrical pumping of the ionic liquid, from a thick nearly solid film that withstands the interplate pressure for high plate charge to complete squeezout following melting near zero charge. Effective enthalpy curves obtained by integration of interplate forces versus distance show the local minima that correspond to layering and predict the switching between one minimum and another under squeezing and charging.
Hołyst, Robert; Litniewski, Marek; Jakubczyk, Daniel
2017-09-13
Transport of heat to the surface of a liquid is a limiting step in the evaporation of liquids into an inert gas. Molecular dynamics (MD) simulations of a two component Lennard-Jones (LJ) fluid revealed two modes of energy transport from a vapour to an interface of an evaporating droplet of liquid. Heat is transported according to the equation of temperature diffusion, far from the droplet of radius R. The heat flux, in this region, is proportional to temperature gradient and heat conductivity in the vapour. However at some distance from the interface, Aλ, (where λ is the mean free path in the gas), the temperature has a discontinuity and heat is transported ballistically i.e. by direct individual collisions of gas molecules with the interface. This ballistic transport reduces the heat flux (and consequently the mass flux) by the factor R/(R + Aλ) in comparison to the flux obtained from temperature diffusion. Thus it slows down the evaporation of droplets of sizes R ∼ Aλ and smaller (practically for sizes from 10 3 nm down to 1 nm). We analyzed parameter A as a function of interactions between molecules and their masses. The rescaled parameter, A(k B T b /ε 11 ) 1/2 , is a linear function of the ratio of the molecular mass of the liquid molecules to the molecular mass of the gas molecules, m 1 /m 2 (for a series of chemically similar compounds). Here ε 11 is the interaction parameter between molecules in the liquid (proportional to the enthalpy of evaporation) and T b is the temperature of the gas in the bulk. We tested the predictions of MD simulations in experiments performed on droplets of ethylene glycol, diethylene glycol, triethylene glycol and tetraethylene glycol. They were suspended in an electrodynamic trap and evaporated into dry nitrogen gas. A changes from ∼1 (for ethylene glycol) to approximately 10 (for tetraethylene glycol) and has the same dependence on molecular parameters as obtained for the LJ fluid in MD simulations. The value of x = A
Alternative Hamiltonian for molecular dynamics simulations in the grand canonical ensemble
International Nuclear Information System (INIS)
Lo, C.; Palmer, B.
1995-01-01
An alternative to the Hamiltonian of Cagin and Pettitt for performing molecular dynamics simulations in the grand canonical ensemble is presented and used as the basis for a new algorithm. The algorithm is tested on the ideal gas and the truncated and shifted Lennard-Jones fluid. Simulations are used to calculate the vapor--liquid coexistence points for the Lennard-Jones system and are found to be in agreement with previous calculations using Gibbs ensemble calculations and with the Nicolas equation of state. Simulations are also performed on the Lennard-Jones solid
International Nuclear Information System (INIS)
Rotarescu, G.
1981-01-01
Measurements of inelastic scattering of soft neutrons on Bi and liquid Pb, applying all the necessary corrections in view of obtaining the dYnamic structure factor S(Q,ω) were performed. The F(Q,t) function of intermediate scattering was obtained by means of the Fourier transformation of S(Q,ω). Special attention was devoted to one multiple scattering correction, especially at small scattering angles, taking into account its influence on the results. A comparison of the experimental results with three recent theoretical models has shown a good agreement in the range of intermediate and high Q values. Measurements of neutron inelastic scattering on liquid sodium at a temperature of 233 Cdeg within a momentum transfer range of 1 A -1 -1 were performed. The scattering law S(α,β) that was compared to a series of theoretical models has been determined from the experimental data. The validity of the theoretical models for different ranges of energy and momenta was thoroughly checked. S(α,β) was calculated for each type of scattering since sodium proves a mixed, coherent and incoherent scattering agent. A study on the influence of the even interaction potential upon the S(Q,ω) dynamic structure factor, the fourth order momentum ω 4 (Q) and uoon the spectral function C(Q,ω) of longitudinal current correlations was performed. For this purpose, four potentials with oscillations at great distances and a Lennard-Jones type potential were used. (author)
Lu, Qing; Kim, Jaegil; Straub, John E
2013-03-14
The generalized Replica Exchange Method (gREM) is extended into the isobaric-isothermal ensemble, and applied to simulate a vapor-liquid phase transition in Lennard-Jones fluids. Merging an optimally designed generalized ensemble sampling with replica exchange, gREM is particularly well suited for the effective simulation of first-order phase transitions characterized by "backbending" in the statistical temperature. While the metastable and unstable states in the vicinity of the first-order phase transition are masked by the enthalpy gap in temperature replica exchange method simulations, they are transformed into stable states through the parameterized effective sampling weights in gREM simulations, and join vapor and liquid phases with a succession of unimodal enthalpy distributions. The enhanced sampling across metastable and unstable states is achieved without the need to identify a "good" order parameter for biased sampling. We performed gREM simulations at various pressures below and near the critical pressure to examine the change in behavior of the vapor-liquid phase transition at different pressures. We observed a crossover from the first-order phase transition at low pressure, characterized by the backbending in the statistical temperature and the "kink" in the Gibbs free energy, to a continuous second-order phase transition near the critical pressure. The controlling mechanisms of nucleation and continuous phase transition are evident and the coexistence properties and phase diagram are found in agreement with literature results.
Bailey, Nicholas P; Bøhling, Lasse; Veldhorst, Arno A; Schrøder, Thomas B; Dyre, Jeppe C
2013-11-14
We derive exact results for the rate of change of thermodynamic quantities, in particular, the configurational specific heat at constant volume, CV, along configurational adiabats (curves of constant excess entropy Sex). Such curves are designated isomorphs for so-called Roskilde liquids, in view of the invariance of various structural and dynamical quantities along them. The slope of the isomorphs in a double logarithmic representation of the density-temperature phase diagram, γ, can be interpreted as one third of an effective inverse power-law potential exponent. We show that in liquids where γ increases (decreases) with density, the contours of CV have smaller (larger) slope than configurational adiabats. We clarify also the connection between γ and the pair potential. A fluctuation formula for the slope of the CV-contours is derived. The theoretical results are supported with data from computer simulations of two systems, the Lennard-Jones fluid, and the Girifalco fluid. The sign of dγ∕dρ is thus a third key parameter in characterizing Roskilde liquids, after γ and the virial-potential energy correlation coefficient R. To go beyond isomorph theory we compare invariance of a dynamical quantity, the self-diffusion coefficient, along adiabats and CV-contours, finding it more invariant along adiabats.
Das, Arya; Ali, Sk. Musharaf
2018-02-01
performing the non-equilibrium molecular dynamics employing the periodic perturbation method. The calculated shear viscosity of the binary mixture is found to be in excellent agreement with the experimental values. The use of the newly calibrated OPLS force field embedding Mulliken charges is shown to be equally reliable in predicting the structural and dynamical properties for the mixture without incorporating any arbitrary scaling in the force field or Lennard-Jones parameters. Further, the present MD simulation results demonstrate that the Stokes-Einstein relation breaks down at the molecular level. The present methodology might be adopted to evaluate the liquid state properties of an aqueous-organic biphasic system, which is of great significance in the interfacial science and technology.
Das, Arya; Ali, Sk Musharaf
2018-02-21
performing the non-equilibrium molecular dynamics employing the periodic perturbation method. The calculated shear viscosity of the binary mixture is found to be in excellent agreement with the experimental values. The use of the newly calibrated OPLS force field embedding Mulliken charges is shown to be equally reliable in predicting the structural and dynamical properties for the mixture without incorporating any arbitrary scaling in the force field or Lennard-Jones parameters. Further, the present MD simulation results demonstrate that the Stokes-Einstein relation breaks down at the molecular level. The present methodology might be adopted to evaluate the liquid state properties of an aqueous-organic biphasic system, which is of great significance in the interfacial science and technology.
Modeling the liquid-liquid interface and the transfer of a solute by molecular dynamics simulation
International Nuclear Information System (INIS)
Hayoun, Marc
1990-11-01
Molecular Dynamics method and Lennard-Jones potential functions have been employed to model Liquid-Liquid Interfaces. The variation of the miscibilities between the two liquids is obtained by changing the interaction between the two atomic species. The resulting interfaces have a thickness of about three atomic diameters and are stable on the time scale of the simulation. They have been characterized by the density and pressure profiles. The interfacial tension has also been computed and is of the order of magnitude of experimental values. The diffusion process is anisotropic in the interfacial region: the transverse diffusion coefficient (parallelly to the interface) is higher than the normal one. A qualitative explanation of this behaviour is suggested by considering the pressure tensor. The second part of this work, performed by Molecular Dynamics in the canonical ensemble, is devoted to the kinetic study of the transfer of a solute through the interface. A model of a symmetric interface with an atomic solute has been used. The interaction potential between the solute and the solvents has been built in order to obtain an activation barrier to the transfer. We have computed the mean force exerted by the solvent on the solute as a function of its distance to the interface. The resulting mean force potential corresponds to a free energy difference. The height of the energy barrier involved is about 4 kT. The potential energy and entropy profiles have also been calculated and discussed. The diffusion coefficient of the solute has been computed by equilibrium and non-equilibrium methods. We deduced the friction coefficient of the solvent, which is essential to determine the Kramers transmission coefficient. This coefficient is compared to the one obtained by simulation. Finally, the solute transfer rate constant has been calculated. (author) [fr
Structures of simple liquids in contact with nanosculptured surfaces.
Singh, Swarn Lata; Schimmele, Lothar; Dietrich, S
2015-03-01
We present a density functional study of Lennard-Jones liquids in contact with a nanocorrugated wall. The corresponding substrate potential is taken to exhibit a repulsive hard core and a Van der Waals attraction. The corrugation is modeled by a periodic array of square nanopits. We have used the modified Rosenfeld density functional in order to study the interfacial structure of these liquids which with respect to their thermodynamic bulk state are considered to be deep inside their liquid phase. We find that already considerably below the packing fraction of bulk freezing of these liquids, inside the nanopits a three-dimensional-like density localization sets in. If the sizes of the pits are commensurate with the packing requirements, we observe high-density spots separated from each other in all spatial directions by liquid of comparatively very low density. The number, shape, size, and density of these high-density spots depend sensitively on the depth and width of the pits. Outside the pits, only layering is observed; above the pit openings these layers are distorted with the distortion reaching up to a few molecular diameters. We discuss quantitatively how this density localization is affected by the geometrical features of the pits and how it evolves upon increasing the bulk packing fraction. Our results are transferable to colloidal systems and pit dimensions corresponding to several diameters of the colloidal particles. For such systems the predicted unfolding of these structural changes can be studied experimentally on much larger length scales and more directly (e.g., optically) than for molecular fluids which typically call for sophisticated x-ray scattering.
Energy Technology Data Exchange (ETDEWEB)
Rana, Malay Kumar; Chandra, Amalendu, E-mail: amalen@iitk.ac.in [Department of Chemistry, Indian Institute of Technology Kanpur, Kanpur 208016 (India)
2015-01-21
Atomistic simulations of model nonpolar nanotubes in a Stockmayer liquid are carried out for varying nanotube diameter and nanotube-solvent interactions to investigate solvophobic interactions in generic dipolar solvents. We have considered model armchair type single-walled nonpolar nanotubes with increasing radii from (5,5) to (12,12). The interactions between solute and solvent molecules are modeled by the well-known Lennard-Jones and repulsive Weeks-Chandler-Andersen potentials. We have investigated the density profiles and microscopic arrangement of Stockmayer molecules, orientational profiles of their dipole vectors, time dependence of their occupation, and also the translational and rotational motion of solvent molecules in confined environments of the cylindrical nanopores and also in their external peripheral regions. The present results of structural and dynamical properties of Stockmayer molecules inside and near atomistically rough nonpolar surfaces including their wetting and dewetting behavior for varying interactions provide a more generic picture of solvophobic effects experienced by simple dipolar liquids without any specific interactions such as hydrogen bonds.
Van Hoang, Vo; Teboul, Victor; Odagaki, Takashi
2015-12-24
Via analysis of spatiotemporal arrangements of atoms based on their dynamics in supercooled liquid and glassy states of a 2D monatomic system with a double-well Lennard-Jones-Gauss (LJG) interaction potential, we find a new scenario of dynamical heterogeneity. Atoms with the same or very close mobility have a tendency to aggregate into clusters. The number of atoms with high mobility (and size of their clusters) increases with decreasing temperature passing over a maximum before decreasing down to zero. Position of the peak moves toward a lower temperature if mobility of atoms in clusters is lower together with an enhancement of height of the peak. In contrast, the number of atoms with very low mobility or solidlike atoms (and size of their clusters) has a tendency to increase with decreasing temperature and then it suddenly increases in the vicinity of the glass transition temperature leading to the formation of a glassy state. A sudden increase in the number of strongly correlated solidlike atoms in the vicinity of a glass transition temperature (Tg) may be an origin of a drastical increase in viscosity of the glass-forming systems approaching the glass transition. In fact, we find that the diffusion coefficient decays exponentially with a fraction of solidlike atoms exhibiting a sudden decrease in the vicinity of the glass transition region.
Transport in simple liquids and dense gases: kinetic mean-field theory and the KAC limit
International Nuclear Information System (INIS)
Karkheck, J.; Stell, G.; Martina, E.
1982-01-01
Maximization of entropy is used in conjunction with the BBGKY hierarchy to obtain a closed one-particle kinetic equation. For an interparticle potential of hard-sphere core plus smooth attractive tail, this equation contains a hard-core collision integral, identical to that of the revised Enskog theory, plus a mean-field term which is linear in the tail strength. The thermodynamics contained therein leads directly to the now-standard statistical-mechanical methods to construct a state-dependent effective hard-core potential in relation to a more realistic potential. These methods induce an extension of the transport coefficients to the Lennard-Jones potential. Predictions of the resulting transport theory compare very favorably with thermal conductivity and shear viscosity experimental results for real simple liquids and dense gases, and also with molecular dynamics simulation results. Poor agreement between theory and experiment is found for moderately dense and dilute gases. The kinetic theory also contains an entropy functional and an H-theorem is proven. Extension to mixtures is straightforward and the Kac-limit is discussed in detail
International Nuclear Information System (INIS)
Neumann, Martin; Zoppi, Marco
2002-01-01
We have performed extensive path integral Monte Carlo simulations of liquid and solid neon, in order to derive the kinetic energy as well as the single-particle and pair distribution functions of neon atoms in the condensed phases. From the single-particle distribution function n(r) one can derive the momentum distribution and thus obtain an independent estimate of the kinetic energy. The simulations have been carried out using mostly the semiempirical HFD-C2 pair potential by Aziz et al. [R. A. Aziz, W. J. Meath, and A. R. Allnatt, Chem. Phys. 79, 295 (1983)], but, in a few cases, we have also used the Lennard-Jones potential. The differences between the potentials, as measured by the properties investigated, are not very large, especially when compared with the actual precision of the experimental data. The simulation results have been compared with all the experimental information that is available from neutron scattering. The overall agreement with the experiments is very good
Molar excess volumes of liquid hydrogen and neon mixtures from path integral simulation
International Nuclear Information System (INIS)
Challa, S.R.; Johnson, J.K.
1999-01-01
Volumetric properties of liquid mixtures of neon and hydrogen have been calculated using path integral hybrid Monte Carlo simulations. Realistic potentials have been used for the three interactions involved. Molar volumes and excess volumes of these mixtures have been evaluated for various compositions at 29 and 31.14 K, and 30 atm. Significant quantum effects are observed in molar volumes. Quantum simulations agree well with experimental molar volumes. Calculated excess volumes agree qualitatively with experimental values. However, contrary to the existing understanding that large positive deviations from ideal mixtures are caused due to quantum effects in Ne - H 2 mixtures, both classical as well as quantum simulations predict the large positive deviations from ideal mixtures. Further investigations using two other Ne - H 2 potentials of Lennard - Jones (LJ) type show that excess volumes are very sensitive to the cross-interaction potential. We conclude that the cross-interaction potential employed in our simulations is accurate for volumetric properties. This potential is more repulsive compared to the two LJ potentials tested, which have been obtained by two different combining rules. This repulsion and a comparatively lower potential well depth can explain the positive deviations from ideal mixing. copyright 1999 American Institute of Physics
Effect of surface tension on the behavior of adhesive contact based on Lennard-Jones potential law
Zhu, Xinyao; Xu, Wei
2018-02-01
The present study explores the effect of surface tension on adhesive contact behavior where the adhesion is interpreted by long-range intermolecular forces. The adhesive contact is analyzed using the equivalent system of a rigid sphere and an elastic half space covered by a membrane with surface tension. The long-range intermolecular forces are modeled with the Lennard‒Jones (L‒J) potential law. The current adhesive contact issue can be represented by a nonlinear integral equation, which can be solved by Newton‒Raphson method. In contrast to previous studies which consider intermolecular forces as short-range, the present study reveals more details of the features of adhesive contact with surface tension, in terms of jump instabilities, pull-off forces, pressure distribution within the contact area, etc. The transition of the pull-off force is not only consistent with previous studies, but also presents some new interesting characteristics in the current situation.
International Nuclear Information System (INIS)
Hoover, W.G.; Evans, D.J.; Hickman, R.B.; Ladd, A.J.C.; Ashurst, W.T.; Moran, B.
1980-01-01
A new Hamiltonian method for deformation simulations is related to the Green-Kubo fluctuation theory through perturbation theory and linear-response theory. Numerical results for the bulk and shear viscosity coefficients are compared to corresponding Green-Kubo calculations. Both viscosity coefficients depend similarly on frequency, in a way consistent with enhanced ''long-time tails.''
International Nuclear Information System (INIS)
Piatek, A; Dawid, A; Gburski, Z
2006-01-01
We have simulated (by the molecular dymanics (MD) method) the dynamics of fullerenes (C 60 ) in an extremely small cluster composed of only as many as seven C 60 molecules. The interaction is taken to be the full 60-site pairwise additive Lennard-Jones (LJ) potential which generates both translational and anisotropic rotational motions of each molecule. Our atomically detailed MD simulations discover the plastic phase (no translations but active reorientations of fullerenes) at low energies (temperatures) of the (C 60 ) 7 cluster. We provide the in-depth evidence of the dynamical solid-liquid bistability region in the investigated cluster. Moreover, we confirm the existence of the liquid phase in (C 60 ) 7 , the finding of Gallego et al (1999 Phys. Rev. Lett. 83 5258) obtained earlier on the basis of Girifalco's model, which assumes single-site only and spherically symmetrical interaction between C 60 molecules. We have calculated the translational and angular velocity autocorrelation functions and estimated the diffusion coefficient of fullerene in the liquid phase
Fasoula, S.; Nikitas, P.; Pappa-Louisi, A.
2017-01-01
A series of Microsoft Excel spreadsheets were developed to simulate the process of separation optimization under isocratic and simple gradient conditions. The optimization procedure is performed in a stepwise fashion using simple macros for an automatic application of this approach. The proposed optimization approach involves modeling of the peak…
Diffusion processes and memory effects
International Nuclear Information System (INIS)
Mokshin, Anatolii V; Yulmetyev, Renat M; Haenggi, Peter
2005-01-01
We report the results of the numerical estimation of statistical memory effects in diffusion for two various systems: Lennard-Jones fluids and the model of the Brownian particle in a one-dimensional harmonic lattice. We have found the relation between the diffusion coefficient and the non-Markovity parameter, which is linear for the Lennard-Jones systems in liquid state. The relation between the memory measure and the excess entropy is also discussed here
Gujar, R.B.; Ansari, S.A.; Verboom, Willem; Mohapatra, P.K.
2016-01-01
Extraction chromatography resins, prepared by impregnating two multi-podant diglycolamide ligands, viz. diglycolamide-functionalized calix[4]arene (C4DGA) and tripodal diglycolamide (T-DGA) dissolved in the room temperature ionic liquid 1-butyl-3-methylimidazolium bis(trifluoromethanesulfonyl)amide
Dong, Dengpan; Vatamanu, Jenel P.; Wei, Xiaoyu; Bedrov, Dmitry
2018-05-01
Atomistic molecular dynamics simulations were conducted to study the wetting states of 1-ethyl-3-methylimidazolium bis(trifluoro-methylsulfonyl)-imide ionic liquid (IL) nanodroplets on surfaces with different strengths of van der Waals (VDW) interactions and in the presence of an electric field. By adjusting the depth of Lennard-Jones potential, the van der Waals interaction between the solid surface and ionic liquid was systematically varied. The shape of the droplets was analyzed to extract the corresponding contact angle utilized to characterize wetting states of the nanodroplets. The explored range of surface-IL interactions allowed contact angles ranging from complete IL spreading on the surface to poor wettability. The effect of the external electrical field was explored by adding point charges to the surface atoms. Systems with two charge densities (±0.002 e/atom and ±0.004 e/atom) that correspond to 1.36 V/nm and 2.72 V/nm electric fields were investigated. Asymmetrical wetting states were observed for both cases. At 1.36 V/nm electric field, contributions of IL-surface VDW interactions and Coulombic interactions to the wetting state were competitive. At 2.72 V/nm field, electrostatic interactions dominate the interaction between the nanodroplet and surface, leading to enhanced wettability on all surfaces.
Kazachenko, Sergey; Giovinazzo, Mark; Hall, Kyle Wm; Cann, Natalie M
2015-09-15
A custom code for molecular dynamics simulations has been designed to run on CUDA-enabled NVIDIA graphics processing units (GPUs). The double-precision code simulates multicomponent fluids, with intramolecular and intermolecular forces, coarse-grained and atomistic models, holonomic constraints, Nosé-Hoover thermostats, and the generation of distribution functions. Algorithms to compute Lennard-Jones and Gay-Berne interactions, and the electrostatic force using Ewald summations, are discussed. A neighbor list is introduced to improve scaling with respect to system size. Three test systems are examined: SPC/E water; an n-hexane/2-propanol mixture; and a liquid crystal mesogen, 2-(4-butyloxyphenyl)-5-octyloxypyrimidine. Code performance is analyzed for each system. With one GPU, a 33-119 fold increase in performance is achieved compared with the serial code while the use of two GPUs leads to a 69-287 fold improvement and three GPUs yield a 101-377 fold speedup. © 2015 Wiley Periodicals, Inc.
Directory of Open Access Journals (Sweden)
Surekha Ramulu
2012-01-01
Full Text Available Aims: Liquid dish washing solution (DWS was used as a substitute for xylene to dewax tissue sections during hematoxylin and eosin (H and E staining. The aim was to test and compare the hypothesis that xylene-ethanol free (XEF sections deparaffinized with diluted DWS are better than or at par with the conventional H and E sections. Materials and Methods: Fifty paraffin-embedded tissue blocks was included. One section was stained with conventional HandE (group A and the other with XEF HandE (group B staining method. Slides were scored for parameters: nuclear, cytoplasmic, clarity, uniformity, and crispness of staining. Z test was used for statistical analysis. For accuracy of diagnosis, sensitivity, specificity, positive predictive value, and negative predictive value were tested. Results: Adequate nuclear staining was noted in 94% in group A and 96% in group B, -adequate cytoplasmic staining in 92% in group A and 86% in group B, clarity in 94% of group A and 96% of group B sections, uniform staining in 92% of group A and 80% of group B sections, crisp stain in 96% of group A and 88% of group B sections, and 94% of group A sections stained adequately for diagnosis as compared with 90% in group B sections. Conclusion: Liquid DWS can be used as an alternative and effective substitute to xylene and ethanol in routine HandE staining procedure.
Verschuuren, Gerard M
2013-01-01
Covering a variety of Excel simulations, from gambling to genetics, this introduction is for people interested in modeling future events, without the cost of an expensive textbook. The simulations covered offer a fun alternative to the usual Excel topics and include situations such as roulette, password cracking, sex determination, population growth, and traffic patterns, among many others.
Moon, Gi Jong; Yang, Yu Dong; Oh, Jung Min; Kang, In Seok
2017-11-01
Osmotic pressure plays an important role in the processes of charging and discharging of lithium batteries. In this work, osmotic pressure of the ionic liquids confined inside a nanoslit is calculated by using both MD simulation and continuum approach. In the case of MD simulation, an ionic liquid is modeled as singly charged spheres with a short-ranged repulsive Lennard-Jones potential. The radii of the spheres are 0.5nm, reflecting the symmetry of ion sizes for simplicity. The simulation box size is 11nm×11nm×7.5nm with 1050 ion pairs. The concentration of ionic liquid is about 1.922mol/L, and the total charge on an individual wall varies from +/-60e(7.944 μm/cm2) to +/-600e(79.44 μm/cm2) . In the case of continuum approach, we classify the problems according to the correlation length and steric factor, and considered the four separate cases: 1) zero correlation length and zero steric factor, 2) zero correlation length and non-zero steric factor, 3) non-zero correlation length and zero steric factor, and 4) non-zero correlation and non-zero steric factor. Better understanding of the osmotic pressure of ionic liquids confined inside a nanoslit can be achieved by comparing the results of MD simulation and continuum approach. This research was supported by the National Research Foundation of Korea (NRF) Grant funded by the Korea government (MSIP: Ministry of Science, ICT & Future Planning) (No. 2017R1D1A1B05035211).
Calculation of Liquid Water-Hydrate-Methane Vapor Phase Equilibria from Molecular Simulations
DEFF Research Database (Denmark)
Jensen, Lars; Thomsen, Kaj; von Solms, Nicolas
2010-01-01
using the TIP4P/ice potential and a united-atom Lennard-Jones potential. respectively. The equilibrium calculation method for this system has three components, (i) thermodynamic integration from a supercritical ideal gas to obtain the fluid-phase chemical potentials. (ii) calculation of the chemical...
Directory of Open Access Journals (Sweden)
Trond S. Ingebrigtsen
2012-03-01
Full Text Available This paper is an attempt to identify the real essence of simplicity of liquids in John Locke’s understanding of the term. Simple liquids are traditionally defined as many-body systems of classical particles interacting via radially symmetric pair potentials. We suggest that a simple liquid should be defined instead by the property of having strong correlations between virial and potential-energy equilibrium fluctuations in the NVT ensemble. There is considerable overlap between the two definitions, but also some notable differences. For instance, in the new definition simplicity is not a direct property of the intermolecular potential because a liquid is usually only strongly correlating in part of its phase diagram. Moreover, not all simple liquids are atomic (i.e., with radially symmetric pair potentials and not all atomic liquids are simple. The main part of the paper motivates the new definition of liquid simplicity by presenting evidence that a liquid is strongly correlating if and only if its intermolecular interactions may be ignored beyond the first coordination shell (FCS. This is demonstrated by NVT simulations of the structure and dynamics of several atomic and three molecular model liquids with a shifted-forces cutoff placed at the first minimum of the radial distribution function. The liquids studied are inverse power-law systems (r^{-n} pair potentials with n=18,6,4, Lennard-Jones (LJ models (the standard LJ model, two generalized Kob-Andersen binary LJ mixtures, and the Wahnstrom binary LJ mixture, the Buckingham model, the Dzugutov model, the LJ Gaussian model, the Gaussian core model, the Hansen-McDonald molten salt model, the Lewis-Wahnstrom ortho-terphenyl model, the asymmetric dumbbell model, and the single-point charge water model. The final part of the paper summarizes properties of strongly correlating liquids, emphasizing that these are simpler than liquids in general. Simple liquids, as defined here, may be
Barreto, Humberto
2015-01-01
This article is not the usual Excel pedagogy fare in that it does not provide an application or example taught via a spreadsheet. Instead, it briefly reviews the history of spreadsheets in the economics classroom and explores the current environment, with an emphasis on modern learning theory. The conclusion is not surprising: spreadsheets improve…
DEFF Research Database (Denmark)
Adeyemi, Oluseyi
2011-01-01
Sourcing Excellence is one of the key performance indicators (KPIs) in this world of ever changing sourcing strategies. Manufacturing companies need to access and diagnose the reliability and competencies of existing suppliers in order to coordinate and develop them. This would help in managing...
Termodinâmica estatística de líquidos com o método de Monte Carlo. II. O líquido clorofórmio
Directory of Open Access Journals (Sweden)
Barlette Vania Elisabeth
1999-01-01
Full Text Available Thermodynamic properties and radial distribution functions for liquid chloroform were calculated using the Monte Carlo method implemented with Metropolis algorithm in the NpT ensemble at 298 K and 1 atm. A five site model was developed to represent the chloroform molecules. A force field composed by Lennard-Jones and Coulomb potential functions was used to calculate the intermolecular energy. The partial charges needed to represent the Coulombic interactions were obtained from quantum chemical ab initio calculations. The Lennard-Jones parameters were adjusted to reproduce experimental values for density and enthalpy of vaporization for pure liquid. All thermodynamic results are in excelent agreement with experimental data. The correlation functions calculated are in good accordance with theoretical results avaliable in the literature. The free energy for solvating one chloroform molecule into its own liquid at 298 K and 1 atm was computed as an additional test of the potential model. The result obtained compares well with the experimental value. The medium effects on cis/trans convertion of a hypotetical solute in water TIP4P and chloroform solvents were also accomplished. The results obtained from this investigation are in agreement with estimates of the continuous theory of solvation.
Towards understanding the structure and capacitance of electrical double layer in ionic liquids
Energy Technology Data Exchange (ETDEWEB)
Fedorov, Maxim V. [Max Planck Institute for Mathematics in the Sciences, D 04103 Leipzig (Germany); Unilever Centre for Molecular Science Informatics, Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW (United Kingdom); Kornyshev, Alexei A. [Department of Chemistry, Faculty of Natural Sciences, Imperial College London, SW7 2AZ London (United Kingdom)
2008-10-01
In order to understand basic principles of the double layer formation in room temperature ionic liquids, we have performed Molecular Dynamic simulations for a simplified system: dense assembly of charged Lennard-Jones spheres between charged walls. For simplicity, in this first investigation we have considered the cations and anions of the same size. We have calculated the corresponding values of the double layer capacitance as a function of the electrode potential and compared the results with existing theories. We have found that the capacitance curve does not follow the U-shape of the Gouy-Chapman theory, but has a bell-shape in agreement with the mean-field theory that takes into account the effect of limited maximum packing of ions. The wings of capacitance decrease inversely proportional to the square root of the electrode potential, as prescribed by the mean-field theory and the charge conservation law at large electrode polarizations. We have found, however, that the mean-field theory does not quantitatively reproduce the simulation results at small electrode potentials, having detected their remarkable overscreening effects (ionic correlations). The plots for the distributions of ions near the electrode at different electrode charges show that for the considered system, unlike it is often assumed, the double layer is not one layer thick. The overscreening effects, dominating near the potential of zero charge (p.z.c.), are suppressed by the high electrode polarizations, following the onset of the so-called 'lattice saturation effect'. The maximum of the capacitance coincides with the p.z.c., but it is true only for this 'symmetric' system. If sizes of cations and anions are different the maximum will be shifted away from the p.z.c., and generally the shape of the capacitance curve could be more complicated. (author)
International Nuclear Information System (INIS)
Bower, T.
1992-01-01
Syncrude Canada Ltd., operator of the oil sands mine and processing plant near Fort McMurray, Alberta, produces 11% of Canada's crude oil and is the country's largest private-sector employer of native Canadians. Syncrude has the goal of employing about 10% native Canadians, which is about the percentage of natives in the regional population. Examples are presented of successful native employment and entrepreneurship at Syncrude. Doreen Janvier, once employed at Syncrude's mine wash bays, was challenged to form her own company to contract out labor services. Her company, DJM Enterprises, now has a 2-year contract to operate three highly sophisticated wash bays used to clean mining equipment, and is looking to bid on other labor contracts. Mabel Laviolette serves as liaison between the oil containment and recovery team, who recover oil skimmed off Syncrude's tailings basin, and the area manager. The team approach and the seasonal nature of the employment fit in well with native cultural patterns. The excellence of native teamwork is also illustrated in the mine rescue team, one unit of which is entirely native Canadian. Part of Syncrude's aboriginal policy is to encourage development of aboriginal enterprises, such as native-owned Clearwater Welding and Fabricating Ltd., which has held welding and fabricating contracts with most major companies in the region and is a major supplier of skilled tradesmen to Syncrude. Syncrude also provides employment and training, encourages natives to continue their education, and promotes local community development. 4 figs
Tsoupikova, Daria
2007-02-01
This paper describes the research and development of a virtual reality visualization project "Passing excellence" about the world famous architectural ensemble "Kizhi". The Kizhi Pogost is located on an island in Lake Onega in northern Karelia in Russia. It is an authentic museum of an ancient wood building tradition which presents a unique artistic achievement. This ensemble preserves a concentration of masterpieces of the Russian heritage and is included in the List of Most Endangered Sites of the World Monuments Watch protected by World Heritage List of UNESCO. The project strives to create a unique virtual observation of the dynamics of the architectural changes of the museum area beginning from the 15th Century up to the 21st Century. The visualization is being created to restore the original architecture of Kizhi island based on the detailed photographs, architectural and geometric measurements, textural data, video surveys and resources from the Kizhi State Open-Air Museum archives. The project is being developed using Electro, an application development environment for the tiled display high-resolution graphics visualization system and can be shown on the virtual reality systems such as the GeoWall TM and the C-Wall.
Molecular interactions and thermal transport in ionic liquids with carbon nanomaterials.
França, João M P; Nieto de Castro, Carlos A; Pádua, Agílio A H
2017-07-05
We used molecular dynamics simulation to study the effect of suspended carbon nanomaterials, nanotubes and graphene sheets, on the thermal conductivity of ionic liquids, an issue related to understanding the properties of nanofluids. One important aspect that we developed is an atomistic model of the interactions between the organic ions and carbon nanomaterials, so we did not rely on existing force fields for small organic molecules or assume simple combining rules to describe the interactions at the liquid/material interface. Instead, we used quantum calculations with a density functional suitable for non-covalent interactions to parameterize an interaction model, including van der Waals terms and also atomic partial charges on the materials. We fitted a n-m interaction potential function with n values of 9 or 10 and m values between 5 and 8, so a 12-6 Lennard-Jones function would not fit the quantum calculations. For the atoms of ionic liquids and carbon nanomaterials interacting among themselves, we adopted existing models from the literature. We studied the imidazolium ionic liquids [C 4 C 1 im][SCN], [C 4 C 1 im][N(CN) 2 ], [C 4 C 1 im][C(CN) 3 ] and [C 4 C 1 im][(CF 3 SO 2 ) 2 N]. Attraction is stronger for cations (than for anions) above and below the π-system of the nanomaterials, whereas anions show stronger attraction for the hydrogenated edges. The ordering of ions around and inside (7,7) and (10,10) single-walled nanotubes, and near a stack of graphene sheets, was analysed in terms of density distribution functions. We verified that anions are found, as well as cations, in the first interfacial layer interacting with the materials, which is surprising given the interaction potential surfaces. The thermal conductivity of the ionic liquids and of composite systems containing one nanotube or one graphene stack in suspension was calculated using non-equilibrium molecular dynamics. Thermal conductivity was calculated along the axis of the nanotube and
Heterogeneous nucleation from a supercooled ionic liquid on a carbon surface.
He, Xiaoxia; Shen, Yan; Hung, Francisco R; Santiso, Erik E
2016-12-07
Classical molecular dynamics simulations were used to study the nucleation of the crystal phase of the ionic liquid [dmim + ][Cl - ] from its supercooled liquid phase, both in the bulk and in contact with a graphitic surface of D = 3 nm. By combining the string method in collective variables [Maragliano et al., J. Chem. Phys. 125, 024106 (2006)], with Markovian milestoning with Voronoi tessellations [Maragliano et al., J. Chem. Theory Comput. 5, 2589-2594 (2009)] and order parameters for molecular crystals [Santiso and Trout, J. Chem. Phys. 134, 064109 (2011)], we computed minimum free energy paths, the approximate size of the critical nucleus, the free energy barrier, and the rates involved in these nucleation processes. For homogeneous nucleation, the subcooled liquid phase has to overcome a free energy barrier of ∼85 kcal/mol to form a critical nucleus of size ∼3.6 nm, which then grows into the monoclinic crystal phase. This free energy barrier becomes about 42% smaller (∼49 kcal/mol) when the subcooled liquid phase is in contact with a graphitic disk, and the critical nucleus formed is about 17% smaller (∼3.0 nm) than the one observed for homogeneous nucleation. The crystal formed in the heterogeneous nucleation scenario has a structure that is similar to that of the bulk crystal, with the exception of the layers of ions next to the graphene surface, which have larger local density and the cations lie with their imidazolium rings parallel to the graphitic surface. The critical nucleus forms near the graphene surface separated only by these layers of ions. The heterogeneous nucleation rate (∼4.8 × 10 11 cm -3 s -1 ) is about one order of magnitude faster than the homogeneous rate (∼6.6 × 10 10 cm -3 s -1 ). The computed free energy barriers and nucleation rates are in reasonable agreement with experimental and simulation values obtained for the homogeneous and heterogeneous nucleation of other systems (ice, urea, Lennard-Jones spheres, and oxide
Chen, M; Sumorok, K; Zhang, X; Gaudreau, M P J; Akimov, D Y; Bolozdynya, A I; Churakov, D; Chernyshov, V; Koutchenkov, A; Kovalenko, A; Kuzichev, V F; Lamkov, V A; Lebedenko, V; Gusev, L; Safronov, G A; Sheinkman, V A; Smirnov, G; Krasnokutsky, R N; Shuvalov, R S; Fedyakin, N N; Sushkov, V V; Akopyan, M V; Gougas, Andreas; Pevsner, A; CERN. Geneva. Detector Research and Development Committee
1993-01-01
Recent test beam data have shown fast and large signals for LKr, mixed with >1% LXe. Excellent uniformity in LKr and LXe was achieved over a 37 cm long cell. CsI cathode works well inside LKr/LXe with O(1%) resolution at 5 MeV. Precision calibration in-situ has been demonstrated. Scintillating LKr/LXe detectors are sufficiently radiation hard for LHC environment. These new developments simplify the construction of prototype LKr calorimeter, to demonstrate the superior e/gamma energy resolution and the determination of photon direction using longitudinal and transverse segmentations, which are vital for the detection of the multi-photon states. The constant term in the energy resolution is small, the electronics noise is negligible due to the large signal size. The overall pion/electron suppression is expected to be better than 10-4.
Excel Initiative: Excellence in Youth Programming
Directory of Open Access Journals (Sweden)
Lynne M. Borden
2015-06-01
Full Text Available The Excellence in Youth Programming (Excel Initiative strives to support youth programs in delivering high quality programs. The backbone of Excel is the Youth Development Observational Tool (YDOT which allows for the virtual assessment of program staff who work with children and youth ages 9-18 years. The YDOT also allows Excel to provide structured feedback to programs. Excel has several unique features, including a virtual platform and a focus on the relationships between adults and youth participating in after-school programs. Offering structured assessment and interaction online eliminates expenses, provides convenient access for programs around the globe, and allows for unobtrusive assessment of worker-youth interactions. Excel is also integrated into a broader network of resources, tools, and research for those working with children and youth ages 9-18.
Bernardes, Carlos E S; Canongia Lopes, José N; Minas da Piedade, Manuel E
2013-10-31
A previously developed OPLS-based all-atom force field for organometallic compounds was extended to a series of first-, second-, and third-row transition metals based on the study of M(CO)(n) (M = Cr, Fe, Ni, Mo, Ru, or W) complexes. For materials that are solid at ambient temperature and pressure (M = Cr, Mo, W) the validation of the force field was based on reported structural data and on the standard molar enthalpies of sublimation at 298.15 K, experimentally determined by Calvet-drop microcalorimetry using samples corresponding to a specific and well-characterized crystalline phase: Δ(sub)H(m)° = 72.6 ± 0.3 kJ·mol(–1) for Cr(CO)(6), 73.4 ± 0.3 kJ·mol(–1) for Mo(CO)(6), and 77.8 ± 0.3 kJ·mol(–1) for W(CO)(6). For liquids, where problems of polymorphism or phase mixtures are absent, critically analyzed literature data were used. The force field was able to reproduce the volumetric properties of the test set (density and unit cell volume) with an average deviations smaller than 2% and the experimentally determined enthalpies of sublimation and vaporization with an accuracy better than 2.3 kJ·mol(–1). The Lennard-Jones (12-6) potential function parameters used to calculate the repulsive and dispersion contributions of the metals within the framework of the force field were found to be transferable between chromium, iron, and nickel (first row) and between molybdenum and ruthenium (second row).
NVU dynamics. I. Geodesic motion on the constant-potential-energy hypersurface
DEFF Research Database (Denmark)
Ingebrigtsen, Trond; Toxværd, Søren; Heilmann, Ole
2011-01-01
that ensures potential-energy and step-length conservation; center-of-mass drift is also eliminated. Analytical arguments confirmed by simulations demonstrate that the modified NVU algorithm is absolutely stable. Finally, we present simulations showing that the NVU algorithm and the standard leap-frog NVE......An algorithm is derived for computer simulation of geodesics on the constant-potential-energy hypersurface of a system of N classical particles. First, a basic time-reversible geodesic algorithm is derived by discretizing the geodesic stationarity condition and implementing the constant......-potential-energy constraint via standard Lagrangian multipliers. The basic NVU algorithm is tested by single-precision computer simulations of the Lennard-Jones liquid. Excellent numerical stability is obtained if the force cutoff is smoothed and the two initial configurations have identical potential energy within machine...
Validity of the Rosenfeld relationship: A comparative study of the ...
Indian Academy of Sciences (India)
ATREYEE BANERJEE
we find that the NTW model has mixed characteristics of simple liquids and ionic melts. Our study further ... and the value of the Rosenfeld exponents are differ- ent from that found for ..... Lennard-Jones chains J. Chem. Phys. 129 164904. 4.
Pramana – Journal of Physics | Indian Academy of Sciences
Indian Academy of Sciences (India)
Home; Journals; Pramana – Journal of Physics. O akinlade. Articles written in Pramana – Journal of Physics. Volume 64 Issue 2 February 2005 pp 269-279 Research Articles. Structures and autocorrelation functions of liquid Al and Mg modelled via Lennard-Jones potential from molecular dynamics simulation.
Indian Academy of Sciences (India)
Home; Journals; Pramana – Journal of Physics. G A Adebayo. Articles written in Pramana – Journal of Physics. Volume 64 Issue 2 February 2005 pp 269-279 Research Articles. Structures and autocorrelation functions of liquid Al and Mg modelled via Lennard-Jones potential from molecular dynamics simulation.
Pramana – Journal of Physics | Indian Academy of Sciences
Indian Academy of Sciences (India)
Home; Journals; Pramana – Journal of Physics. L A Hussain. Articles written in Pramana – Journal of Physics. Volume 64 Issue 2 February 2005 pp 269-279 Research Articles. Structures and autocorrelation functions of liquid Al and Mg modelled via Lennard-Jones potential from molecular dynamics simulation.
On the equilibrium contact angle of sessile liquid drops from molecular dynamics simulations.
Ravipati, Srikanth; Aymard, Benjamin; Kalliadasis, Serafim; Galindo, Amparo
2018-04-28
We present a new methodology to estimate the contact angles of sessile drops from molecular simulations by using the Gaussian convolution method of Willard and Chandler [J. Phys. Chem. B 114, 1954-1958 (2010)] to calculate the coarse-grained density from atomic coordinates. The iso-density contour with average coarse-grained density value equal to half of the bulk liquid density is identified as the average liquid-vapor (LV) interface. Angles between the unit normal vectors to the average LV interface and unit normal vector to the solid surface, as a function of the distance normal to the solid surface, are calculated. The cosines of these angles are extrapolated to the three-phase contact line to estimate the sessile drop contact angle. The proposed methodology, which is relatively easy to implement, is systematically applied to three systems: (i) a Lennard-Jones (LJ) drop on a featureless LJ 9-3 surface; (ii) an SPC/E water drop on a featureless LJ 9-3 surface; and (iii) an SPC/E water drop on a graphite surface. The sessile drop contact angles estimated with our methodology for the first two systems are shown to be in good agreement with the angles predicted from Young's equation. The interfacial tensions required for this equation are computed by employing the test-area perturbation method for the corresponding planar interfaces. Our findings suggest that the widely adopted spherical-cap approximation should be used with caution, as it could take a long time for a sessile drop to relax to a spherical shape, of the order of 100 ns, especially for water molecules initiated in a lattice configuration on a solid surface. But even though a water drop can take a long time to reach the spherical shape, we find that the contact angle is well established much faster and the drop evolves toward the spherical shape following a constant-contact-angle relaxation dynamics. Making use of this observation, our methodology allows a good estimation of the sessile drop contact
McFedries, Paul
2013-01-01
A friendly, visual approach to learning the basics of Excel 2013 As the world's leading spreadsheet program, Excel is a spreadsheet and data analysis tool that is part of the Microsoft Office suite. The new Excel 2013 includes new features and functionalities that require users of older versions to re-learn the application. However, whether you're switching from an earlier version or learning Excel for the first time, this easy-to-follow visual guide gets you going with Excel 2013 quickly and easily. Numbered steps as well as full-color screen shots, concise information, and helpfu
Katz, Abbott
2011-01-01
Get the most out of Excel 2010 with Excel 2010 Made Simple - learn the key features, understand what's new, and utilize dozens of time-saving tips and tricks to get your job done. Over 500 screen visuals and clear-cut instructions guide you through the features of Excel 2010, from formulas and charts to navigating around a worksheet and understanding Visual Basic for Applications (VBA) and macros. Excel 2010 Made Simple takes a practical and highly effective approach to using Excel 2010, showing you the best way to complete your most common spreadsheet tasks. You'll learn how to input, format,
Walkenbach, John
2013-01-01
Maximize the power of Excel 2013 formulas with this must-have Excel reference John Walkenbach, known as ""Mr. Spreadsheet,"" is a master at deciphering complex technical topics and Excel formulas are no exception. This fully updated book delivers more than 800 pages of Excel 2013 tips, tricks, and techniques for creating formulas that calculate, developing custom worksheet functions with VBA, debugging formulas, and much more. Demonstrates how to use all the latest features in Excel 2013 Shows how to create financial formulas and tap into the power of array formulas
Marmel, Elaine
2010-01-01
The complete visual reference on Excel basics. Aimed at visual learners who are seeking an all-in-one reference that provides in-depth coveage of Excel from a visual viewpoint, this resource delves into all the newest features of Excel 2010. You'll explore Excel with helpful step-by-step instructions that show you, rather than tell you, how to navigate Excel, work with PivotTables and PivotCharts, use macros to streamline work, and collaborate with other users in one document.: This two-color guide features screen shots with specific, numbered instructions so you can learn the actions you need
Chemical potential calculations in dense liquids using metadynamics
Perego, C.; Giberti, F.; Parrinello, M.
2016-10-01
The calculation of chemical potential has traditionally been a challenge in atomistic simulations. One of the most used approaches is Widom's insertion method in which the chemical potential is calculated by periodically attempting to insert an extra particle in the system. In dense systems this method fails since the insertion probability is very low. In this paper we show that in a homogeneous fluid the insertion probability can be increased using metadynamics. We test our method on a supercooled high density binary Lennard-Jones fluid. We find that we can obtain efficiently converged results even when Widom's method fails.
Walkenbach, John
2010-01-01
A comprehensive reference to the newest version of the world's most popular spreadsheet application: Excel 2010 John Walkenbach's name is synonymous with excellence in computer books that decipher complex technical topics. Known as ""Mr. Spreadsheet,"" Walkenbach shows you how to maximize the power of all the new features of Excel 2010. An authoritative reference, this perennial bestseller proves itself indispensable no matter your level of skill, from Excel beginners and intermediate users to power users and potential power users everywhere. Fully updated for the new release, this
"Excellence" in STEM Education
Clark, Aaron C.
2012-01-01
So what does it take to achieve excellence in STEM education? That is the title of the author's presentation delivered at International Technology and Engineering Educators Association's (ITEEA's) FTEE "Spirit of Excellence" Breakfast on March 16, 2012, in Long Beach, California. In preparation for this presentation, the author went back and read…
Beginning Microsoft Excel 2010
Katz, Abbott
2010-01-01
Beginning Microsoft Excel 2010 is a practical, step-by-step guide to getting started with the world's most widely used spreadsheet application. The book offers a hands-on approach to learning how to create and edit spreadsheets, use various calculation formulas, employ charts/graphs, and get work done efficiently. Microsoft is rolling out several new features with Excel 2010 - perhaps the most notable is the ability to use Excel 2010 online and this collaborate on a project in real time. Beginning Microsoft Office 2010 keeps you up-to-date with all of these new features and more. What you'll l
Harvey, Greg
2013-01-01
Every time you turn around, you run into Excel. It's on yourPC at work. It's on your PC at home. You get Excel files fromyour boss. Wouldn't you like to understand this powerfulMicrosoft Office spreadsheet program, once and for all? Now, youcan crunch financial data, add sparkle to presentations, convertstatic lists of numbers into impressive charts, and discover whatall the shouting's about regarding databases, formulas, andcells. You may even decide that getting organized with a goodspreadsheet is downright useful and fun! Flip open Excel 2003 For Dummies, and you'llquickly start getting th
International Nuclear Information System (INIS)
Vaughn, G.E.
1986-01-01
With guidance and assistance from the Institute of Nuclear Power Operations (INPO), nuclear utilities are striving for excellence by making steady improvements in industry performance indicators. Duke Power Company has solidly committed to support the industry's effort to obtain higher standards of excellence. Dedicated, highly trained employees, who are motivated to making it happen, carry out this commitment within a management framework which includes: 1) top management support and direct involvement; 2) a strategy to achieve excellence over the long run; 3) a nuclear management priority structure; and 4) a goals program
Alexander, Michael
2013-01-01
Learn to use Excel dashboards and reports to better conceptualize data Updated for all the?latest features and capabilities of Excel 2013, this go-to resource provides you with in-depth coverage of the individual functions and tools that can be used to create?compelling Excel reports. Veteran author Michael Alexander walks you through the most effective ways to present and report data. Featuring a comprehensive review of a wide array of technical and analytical concepts, this essential guide helps you go from reporting data with simple tables full of dull numbers to presenting
Walkenbach, John
2011-01-01
Everything you need to know about* Mastering operators, error values, naming techniques, and absolute versus relative references* Debugging formulas and using the auditing tools* Importing and exporting XML files and mapping the data to specific cells* Using Excel 2003's rights management feature* Working magic with array formulas* Developing custom formulas to produce the results you needHere's the formula for Excel excellenceFormulas are the lifeblood of spreadsheets, and no one can bring a spreadsheet to life like John Walkenbach. In this detailed reference guide, he delves deeply into unde
Sustainable Enterprise Excellence
DEFF Research Database (Denmark)
Edgeman, Rick; Williams, Joseph; Eskildsen, Jacob Kjær
, supply chain, customer-related, human capital, financial, marketplace, societal, and environmental performance. Sustainable Enterprise Excellence integrates ethical, efficient and effective (E3) enterprise governance with 3E (equity, ecology, economy) Triple Top Line strategy throughout enterprise...
Indian Academy of Sciences (India)
Lawrence
dia and develop new areas of research in their perspective laborato- ries. A staunch ... Her unique quality for allowing individual scientific tal- ents to bloom, in ... of excellence in sci- ence, Dr Ranadive made an indelible impression on my mind.
DEFF Research Database (Denmark)
Hattke, Fabian; Blaschke, Steffen
2015-01-01
Purpose: - The purpose of this paper is to evaluate the influence of top management team diversity on academic excellence in universities. Academic excellence is conceptualized as successfully gaining funds for inter-organizational research collaborations, interdisciplinary graduate schools......, and high ranked scientific reputation. Design/methodology/approach: -The study applies upper echelon theory to universities. Three hypotheses are developed: 1) (Overall) top management team heterogeneity is positively associated with successful funding of excellence clusters, 2) (Overall) top management...... no significant effects. Besides top management team composition, we find that a high number of faculties and a broad inclusion of internal status groups (students, tenured faculty, academic and administrative staff) and external stakeholders in decision making processes may enhance academic excellence...
Sustainable Enterprise Excellence
DEFF Research Database (Denmark)
Edgeman, Rick
2013-01-01
Structured Abstract Purpose: Sustainable Enterprise Excellence (SEE) is defined and developed through integration and expansion of business excellence modeling and sustainability thought. The intent is to enable simple yet reliable enterprise assessment of triple bottom line (TBL) performance...... and produce actionable enterprise foresight that can enable next best practices and sources of sustainable competitive advantage through innovation. Methodology: Key elements of SEE are identified from various business excellence and sustainability reporting sources, including the Global Reporting Initiative...... assessment approach similar in structure to those behind established excellence awards are developed that enable enterprise assessment of progress toward SEE. The resulting assessment is delivered in a highly consumable, combined narrative and graphic format referred to as a SEE NEWS Report. Practical...
Achieveing Organizational Excellence Through
Mehdi Abzari; Mohammadreza Dalvi
2009-01-01
AbstractToday, In order to create motivation and desirable behavior in employees, to obtain organizational goals,to increase human resources productivity and finally to achieve organizational excellence, top managers oforganizations apply new and effective strategies. One of these strategies to achieve organizational excellenceis creating desirable corporate culture. This research has been conducted to identify the path to reachorganizational excellence by creating corporate culture according...
Leading Others Toward Excellence.
Hupp, James R
2015-12-01
This essay puts forth the proposition that academic program excellence does not arise by accident. Effective leadership is required. To support this proposition, the essay discusses the characteristics common to effective leaders. It then proceeds to use the example of a successful academic oral-maxillofacial surgery department and characteristics of its leader to provide evidence that excellence derives from effective leadership. Copyright © 2015 American Association of Oral and Maxillofacial Surgeons. Published by Elsevier Inc. All rights reserved.
A perspective on the interfacial properties of nanoscopic liquid drops
International Nuclear Information System (INIS)
Malijevský, Alexandr; Jackson, George
2012-01-01
century by Gibbs and then promoted by Tolman) with a microscopic DFT treatment allows for a direct and unambiguous description of the interfacial properties of drops of arbitrary size; DFT provides all of the bulk and surface characteristics of the system that are required to uniquely define its thermodynamic properties. In this vein, we propose a non-local mean-field DFT for Lennard-Jones (LJ) fluids to examine drops of varying size. A comparison of the predictions of our DFT with recent simulation data based on a second-order fluctuation analysis (Sampayo et al 2010 J. Chem. Phys. 132 141101) reveals the consistency of the two treatments. This observation highlights the significance of fluctuation effects in small drops, which give rise to additional entropic (thermal non-mechanical) contributions, in contrast to what one observes in the case of planar interfaces which are governed by the laws of mechanical equilibrium. A small negative Tolman length (which is found to be about a tenth of the molecular diameter) and a non-monotonic behaviour of the surface tension with the drop radius are predicted for the LJ fluid. Finally, the limits of the validity of the Tolman approach, the effect of the range of the intermolecular potential, and the behaviour of bubbles are briefly discussed.
International Nuclear Information System (INIS)
Gysel, T.
2016-01-01
Full text: Nuclear organizations now wishing to become much more effective as an organization require further advice and specific guidance, drawn from validated international best practices in the development and implementation of Knowledge Management in the context of the organization’s management system. Therefore the IAEA Nuclear Knowledge Management Section is developing an approach for implementing Knowledge Management in the context of a management system. What looks like excellence today, may not be tomorrow. Best-in-class competitors, technology, and management paradigms all evolve. Second, true Operational Excellence manifests itself through integrated performance across revenue, cost, and risk. (author
Achieving excellence in training
International Nuclear Information System (INIS)
Mangin, A.M.; Solymossy, J.M.
1983-01-01
Operating a nuclear power plant is a uniquely challenging activity, requiring a high degree of competence from all who are involved. Achieving and maintaining this competence requires excellence in training. But what does excellence mean, and how do we achieve it. Based on the experience gained by INPO in plant training evaluations and accreditation activities, this paper describes some of the actions that can be taken to achieve the quality appropriate for nuclear power plant training. These actions are discussed in relation to the four phases of a performance-based training system: (1) needs analysis, (2) program design and development, (3) implementation, and (4) evaluation and improvement
Culler, Jonathan
2002-01-01
Suggests that when the university devotes itself to "excellence," it substitutes, for a vision of what should be taught, a contentless measure, a bureaucratic concept that extends the range of managerial control without presuming to make judgments about content. Suggests that English departments should try to design sequences of courses that are…
A.A.J. van Peet; H.A. Everaert
2007-01-01
In KG-18 hebben we verschillende grafieken laten zien. Een veel gebruikte grafische figuur in de statistiek is de zogenaamde boxplot. Weliswaar wordt deze niet vermeld bij de standaard keuzemogelijkheden onder de Wizard Grafieken, toch is het mogelijk om deze figuur met behulp van Excel te tekenen.
Gas–liquid nucleation at large metastability: unusual features and a new formalism
International Nuclear Information System (INIS)
Santra, Mantu; Singh, Rakesh S; Bagchi, Biman
2011-01-01
to understand the large numerical discrepancy between simulation predictions and experimental results, we carried out a study of the dependence on the range of intermolecular interactions of both the surface tension of an equilibrium planar gas–liquid interface and the free energy barrier of nucleation. Both are found to depend significantly on the range of interaction for the Lennard-Jones potential, both in two and three dimensions. The value of surface tension and also the free energy difference between the gas and the liquid phase increase significantly and converge only when the range of interaction is extended beyond 6–7 molecular diameters. We find, with the full range of interaction potential, that the surface tension shows only a weak dependence on supersaturation, so the reason for the breakdown of CNT (with simulated values of surface tension and free energy gap) cannot be attributed to the supersaturation dependence of surface tension. This remains an unsettled issue at present because of the use of the value of surface tension obtained at coexistence
Gas-liquid nucleation at large metastability: unusual features and a new formalism
Santra, Mantu; Singh, Rakesh S.; Bagchi, Biman
2011-03-01
to understand the large numerical discrepancy between simulation predictions and experimental results, we carried out a study of the dependence on the range of intermolecular interactions of both the surface tension of an equilibrium planar gas-liquid interface and the free energy barrier of nucleation. Both are found to depend significantly on the range of interaction for the Lennard-Jones potential, both in two and three dimensions. The value of surface tension and also the free energy difference between the gas and the liquid phase increase significantly and converge only when the range of interaction is extended beyond 6-7 molecular diameters. We find, with the full range of interaction potential, that the surface tension shows only a weak dependence on supersaturation, so the reason for the breakdown of CNT (with simulated values of surface tension and free energy gap) cannot be attributed to the supersaturation dependence of surface tension. This remains an unsettled issue at present because of the use of the value of surface tension obtained at coexistence.
International Nuclear Information System (INIS)
Bertagnolli, H.
1978-01-01
For the case of special molecular models representing the acetonitrile molecule the expansion coefficients of the molecular par distribution function are calculated by use of pertubation theory. These results are used to get theoretical access to scattering intensities in the frame of several approximations. The first model describes the molecule by three hard spheres and uses a hard sphere liquid as reference. In the second cast the calculations are based on an anisotropic Lennard-Jones potential by application of a model of overlapping ellipsoids and by use of a Lennard-Jones liquid as a reference system. In the third model dipolar attractive forces are taken into account with an anisotropic hard-sphere liquid as a reference. In the third model dipolar attractive forces are taken into account with an anisotropic hard-sphere liquid as a reference. Finally all the calculations with different intermolecular potentials are compared with neutron scattering experiments. (orig.) 891 HK [de
DOE goals: Excellence, openness
International Nuclear Information System (INIS)
Isaacs, T.H.
1989-01-01
The author feels that the benefit of the experience and programmatic resources it has developed since passage of the Nuclear Waste Policy Act in 1982 and of the sound and flexible policy framework provided by the amendments, DOE is confident that program objectives can be met on a schedule that balances the needs for technical excellence, institutional openness, and timely acceptance. As the program evolves, DOE will continue to assess how effectively policies are serving program objectives. The need for flexibility in developing a first-of-a-kind system is essential. But flexibility does not alter the need for program stability, which, in turn, requires a commonly shared commitment to realizing the program's goals. This commitment must rest upon a pragmatic understanding of the realities of waste-management system development
International Nuclear Information System (INIS)
Lasser, Susan J.S.; Snelsire, Robert W.
1992-01-01
This paper describes the first two years of the Clemson University College of Engineering's Math Excellence Workshop, a program administered by Westinghouse Electric Corporation, Savannah River Site, and funded by the Department of Energy. The objective of the program is to prepare minority students for technical/scientific study, with the goal of increasing minority retention in the College of Engineering, Twenty-three African American students, all of whom had been accepted into the College of Engineering Fall 1990 freshman class, took part in the first year of the program. The contract paid for room, board, tuition, fees, books, and supplies for the students to live on campus and take a precalculus math course. In addition, the students attended a special honors workshop designed to prepare them to study technical material effectively. Twenty of the 23 students earned As or Bs in the precalculus class. All participants indicated that they felt confident of their ability to succeed academically at Clemson. At the end of the session, twenty of the students were still planning to major in engineering. The program was repeated the following summer with 24 students from the 1991 freshman class. Twelve of the students earned A's or B's in the precalculus class. (author)
Energy Technology Data Exchange (ETDEWEB)
Lasser, Susan J.S.; Snelsire, Robert W [College of Engineering, Clemson University, Clemson, SC (United States)
1992-07-01
This paper describes the first two years of the Clemson University College of Engineering's Math Excellence Workshop, a program administered by Westinghouse Electric Corporation, Savannah River Site, and funded by the Department of Energy. The objective of the program is to prepare minority students for technical/scientific study, with the goal of increasing minority retention in the College of Engineering, Twenty-three African American students, all of whom had been accepted into the College of Engineering Fall 1990 freshman class, took part in the first year of the program. The contract paid for room, board, tuition, fees, books, and supplies for the students to live on campus and take a precalculus math course. In addition, the students attended a special honors workshop designed to prepare them to study technical material effectively. Twenty of the 23 students earned As or Bs in the precalculus class. All participants indicated that they felt confident of their ability to succeed academically at Clemson. At the end of the session, twenty of the students were still planning to major in engineering. The program was repeated the following summer with 24 students from the 1991 freshman class. Twelve of the students earned A's or B's in the precalculus class. (author)
Directory of Open Access Journals (Sweden)
Simon Drees
2016-07-01
Full Text Available The ASPIRE-to-Excellence Academy was recently founded at the 2015 Association for Medical Education in Europe (AMEE conference in Glasgow. The academy is new pillar of the ASPIRE-to-Excellence initiative by AMEE, which aims at promoting and encouraging medical schools in achieving excellence in the categories of assessment, student engagement, social accountability or faculty development. The Academy panel consists of the members of the ASPIRE Board and representatives from schools which have been recognised with an ASPIRE-to-excellence award in one or more of the categories. Major goal of the ASPIRE-to-Excellence Academy is to foster collaboration between excellent medical schools and to allow them to exchange experiences and Best Practices. The Academy members are organising workshops and symposia at international conferences to inform medical schools about the ASPIRE-to-Excellence programme and the areas for recognition in excellence as well as to support medical school in preparing their applications.
NVU dynamics. II. Comparing to four other dynamics
DEFF Research Database (Denmark)
Ingebrigtsen, Trond; Toxværd, Søren; Schrøder, Thomas
2011-01-01
-potential-energy hypersurface. Here, simulations of NVU dynamics are compared to results for four other dynamics, both deterministic and stochastic. First, NVU dynamics is compared to the standard energy-conserving Newtonian NVE dynamics by simulations of the Kob-Andersen binary Lennard-Jones liquid, its WCA version (i.......e., with cut-off's at the pair potential minima), and the Lennard-Jones Gaussian liquid. We find identical results for all quantities probed: radial distribution functions, incoherent intermediate scattering functions, and mean-square displacement as function of time. Arguments are presented...... on the constant-potential-energy hypersurface, and to Nos-Hoover NVT dynamics. If time is scaled for the two stochastic dynamics to make single-particle diffusion constants identical to that of NVE dynamics, the simulations show that all five dynamics are equivalent at low temperatures except at short times....
Shear-induced phase changes in mixtures
International Nuclear Information System (INIS)
Romig, K.D.; Hanley, H.J.M.
1986-01-01
A thermodynamic theory to account for the behavior of liquid mixtures exposed to a shear is developed. One consequence of the theory is that shear-induced phase changes are predicted. The theory is based on a thermodynamics that includes specifically the shear rate in the formalism and is applied to mixtures by a straightforward modification of the corresponding states, conformalsolution approach. The approach is general but is used here for a mixture of Lennard-Jones particles with a Lennard-Jones equation of state as a reference fluid. The results are discussed in the context of the Scott and Van Konynenberg phase classification. It is shown that the influence of a shear does affect substantially the type of the phase behavior. Results from the model mixture are equated loosely with those from real polymeric liquids
Koperwas, K.; Affouard, F.; Gerges, J.; Valdes, L.-C.; Adrjanowicz, K.; Paluch, M.
2017-12-01
In this paper, we examine, in terms of the classical nucleation theory, how the strengthening of the attractive intermolecular interactions influences the crystallization process for systems like Lennard-Jones at different isobaric conditions. For this purpose, we modify the standard Lennard-Jones potential, and as a result, we obtain three different systems characterized by various strengths of attractive potentials occurring between molecules, which are in direct relationship to the physical quantities describing molecules, e.g., its polarizability or dipole moment. Based on performed analysis, we demonstrate that the molecular attraction primarily impacts the thermodynamics of the interface between liquid and crystal. This is reflected in the behavior of nucleation and overall crystallization rates during compression of the system.
International Nuclear Information System (INIS)
Fay, P.J.; Ray, J.R.; Wolf, R.J.
1994-01-01
We present a new, nondestructive, method for determining chemical potentials in Monte Carlo and molecular dynamics simulations. The method estimates a value for the chemical potential such that one has a balance between fictitious successful creation and destruction trials in which the Monte Carlo method is used to determine success or failure of the creation/destruction attempts; we thus call the method a detailed balance method. The method allows one to obtain estimates of the chemical potential for a given species in any closed ensemble simulation; the closed ensemble is paired with a ''natural'' open ensemble for the purpose of obtaining creation and destruction probabilities. We present results for the Lennard-Jones system and also for an embedded atom model of liquid palladium, and compare to previous results in the literature for these two systems. We are able to obtain an accurate estimate of the chemical potential for the Lennard-Jones system at higher densities than reported in the literature
Molecular dynamic simulation of Copper and Platinum nanoparticles Poiseuille flow in a nanochannels
Toghraie, Davood; Mokhtari, Majid; Afrand, Masoud
2016-10-01
In this paper, simulation of Poiseuille flow within nanochannel containing Copper and Platinum particles has been performed using molecular dynamic (MD). In this simulation LAMMPS code is used to simulate three-dimensional Poiseuille flow. The atomic interaction is governed by the modified Lennard-Jones potential. To study the wall effects on the surface tension and density profile, we placed two solid walls, one at the bottom boundary and the other at the top boundary. For solid-liquid interactions, the modified Lennard-Jones potential function was used. Velocity profiles and distribution of temperature and density have been obtained, and agglutination of nanoparticles has been discussed. It has also shown that with more particles, less time is required for the particles to fuse or agglutinate. Also, we can conclude that the agglutination time in nanochannel with Copper particles is faster that in Platinum nanoparticles. Finally, it is demonstrated that using nanoparticles raises thermal conduction in the channel.
Isomorph invariance of Couette shear flows simulated by the SLLOD equations of motion
DEFF Research Database (Denmark)
Separdar, Leila; Bailey, Nicholas; Schrøder, Thomas
2013-01-01
fluctuations of virial and potential energy. Such systems have good isomorphs (curves in the thermodynamic phase diagram along which structural, dynamical, and some thermodynamic quantities are invariant when expressed in reduced units). The SLLOD equations of motion were used to simulate Couette shear flows......Non-equilibrium molecular dynamics simulations were performed to study the thermodynamic, structural, and dynamical properties of the single-component Lennard-Jones and the Kob-Andersen binary Lennard-Jones liquids. Both systems are known to have strong correlations between equilibrium thermal...... of the two systems. We show analytically that these equations are isomorph invariant provided the reduced strain rate is fixed along the isomorph. Since isomorph invariance is generally only approximate, a range of strain rates were simulated to test for the predicted invariance, covering both the linear...
Molecular dynamics investigation of tracer diffusion in a simple liquid
International Nuclear Information System (INIS)
Ould-Kaddour, F.; Barrat, J.L.
1991-05-01
Extensive Molecular-Dynamics (MD) simulations have been carried out for a model trace-solvent system made up of 100 solvent molecules and 8 tracer molecules interacting through truncated Lennard-Jones potentials. The influence of the size ratio between solute and solvent, of their mass ratio and of the solvent viscosity on the diffusivity of a small tracer were investigated. Positive deviations from a Stokes-Einstein behaviour are observed, in qualitative agreement with experimental observations. It was also observed that as tracer and solvent become increasingly dissimilar, their respective dynamics becomes decoupled. We suggest that such decouplings can be interpreted by writing their mobility of the tracer as the sum of two terms, the first one arising from a coupling between tracer dynamics and hydrodynamics modes of the solvent, and the second one describing jump motion in a locally nearly frozen environment. (author). 17 refs, 4 figs, 6 tabs
Roman, Steven
2008-01-01
To achieve the maximum control and flexibility from Microsoft® Excel often requires careful custom programming using the VBA (Visual Basic for Applications) language. Writing Excel Macros with VBA, 2nd Edition offers a solid introduction to writing VBA macros and programs, and will show you how to get more power at the programming level: focusing on programming languages, the Visual Basic Editor, handling code, and the Excel object model.
Hart-Davis, Guy
2011-01-01
Microsoft Excel 2011 for Mac OS X is a powerful application, but many of its most impressive features can be difficult to find. Learn Excel 2011 for Mac by Guy Hart-Davis is a practical, hands-on approach to learning all of the details of Excel 2011 in order to get work done efficiently on Mac OS X. From using formulas and functions to creating databases, from analyzing data to automating tasks, you'll learn everything you need to know to put this powerful application to use for a variety of tasks. What you'll learn * The secrets of the Excel for Mac interface! * How to create effective workbo
Excel data analysis for dummies
Nelson, Stephen L
2014-01-01
Harness the power of Excel to discover what your numbers are hiding Excel Data Analysis For Dummies, 2nd Edition is the ultimate guide to getting the most out of your data. Veteran Dummies author Stephen L. Nelson guides you through the basic and not-so-basic features of Excel to help you discover the gems hidden in your rough data. From input, to analysis, to visualization, the book walks you through the steps that lead to superior data analysis. Excel is the number-one spreadsheet application, with ever-expanding capabilities. If you're only using it to balance the books, you're missing out
Urtis, Tom
2015-01-01
Master VBA automation quickly and easily to get more out of Excel Excel VBA 24-Hour Trainer, 2nd Edition is the quick-start guide to getting more out of Excel, using Visual Basic for Applications. This unique book/video package has been updated with fifteen new advanced video lessons, providing a total of eleven hours of video training and 45 total lessons to teach you the basics and beyond. This self-paced tutorial explains Excel VBA from the ground up, demonstrating with each advancing lesson how you can increase your productivity. Clear, concise, step-by-step instructions are combined wit
Teaching physics using Microsoft Excel
Uddin, Zaheer; Ahsanuddin, Muhammad; Khan, Danish Ahmed
2017-09-01
Excel is both ubiquitous and easily understandable. Most people from every walk of life know how to use MS office and Excel spreadsheets. Students are also familiar with spreadsheets. Most students know how to use spreadsheets for data analysis. Besides basic use of Excel, some important aspects of spreadsheets are highlighted in this article. MS Excel can be used to visualize effects of various parameters in a physical system. It can be used as a simulating tool; simulation of wind data has been done through spreadsheets in this study. Examples of Lissajous figures and a damped harmonic oscillator are presented in this article.
hugho, Chemli
2017-01-01
His Excellency Mr Farukh Amil Ambassador Extraordinary and Plenipotentiary Permanent Representative of the Islamic Republic of Pakistan to the United Nations Office and other international organisations in Geneva
ARS-Media for Excel is an ion solution calculator that uses Microsoft Excel to generate recipes of salts for complex ion mixtures specified by the user. Generating salt combinations (recipes) that result in pre-specified target ion values is a linear programming problem. Thus, the recipes are genera...
Phase transitions of quadrupolar fluids
International Nuclear Information System (INIS)
OShea, S.F.; Dubey, G.S.; Rasaiah, J.C.
1997-01-01
Gibbs ensemble simulations are reported for Lennard-Jones particles with embedded quadrupoles of strength Q * =Q/(εσ 5 ) 1/2 =2.0 where ε and σ are the Lennard-Jones parameters. Calculations revealing the effect of the dispersive forces on the liquid endash vapor coexistence were carried out by scaling the attractive r -6 term in the Lennard-Jones pair potential by a factor λ ranging from 0 to 1. Liquid endash vapor coexistence is observed for all values of λ including λ=0 for Q * =2.0, unlike the corresponding dipolar fluid studied by van Leeuwen and Smit et al. [Phys. Rev. Lett. 71, 3991 (1993)] which showed no phase transition below λ=0.35 when the reduced dipole moment μ * =2.0. The simulation data are analyzed to estimate the critical properties of the quadrupolar fluid and their dependence on the strength λ of the dispersive force. The critical temperature and pressure show a clear quadratic dependence on λ, while the density is less confidently identified as being linear in λ. The compressibility is roughly linear in λ. copyright 1997 American Institute of Physics
Teach yourself visually complete Excel
McFedries, Paul
2013-01-01
Get the basics of Excel and then go beyond with this new instructional visual guide While many users need Excel just to create simple worksheets, many businesses and professionals rely on the advanced features of Excel to handle things like database creation and data analysis. Whatever project you have in mind, this visual guide takes you step by step through what each step should look like. Veteran author Paul McFedries first presents the basics and then gradually takes it further with his coverage of designing worksheets, collaborating between worksheets, working with visual data
Quality Management and Business Excellence
Vasile Dinu
2017-01-01
An excellent organization involves much more than the implementation and the certification of one or more models of management systems. It means developing techniques and tools of busin excellence which lead the organization to outstanding performance on quality, costs and deadlines in order to meet the expectations of all their stakeholders. Such an approach is needed especially in the context of an economy marked by globalization, extremely complex and dynamic that causes spectacular change...
ARS-Media for excel instruction manual
ARS-Media for Excel Instruction Manual is the instruction manual that explains how to use the Excel spreadsheet ARS-Media for Excel application. ARS-Media for Excel Instruction Manual is provided as a pdf file....
Developing talent for operational excellence.
Theadore, Jason C; O'Brien, Thaddeus J
2012-01-01
Many organizations have the expectation that their employees will prepare for their own professional development without much support or guidance. To achieve operational excellence, development of the people in an organization is just as important as the development of technologies and processes. Ohio Health Ambulatory Division in Columbus, OH created a plan to develop its people systematically in three distinct pillars: management development, staff engagement, and clinical excellence. Much was learned about talent development since work began on "The People Plan", perhaps the most critical lesson learned has been the importance of not giving up on the effort.
International Nuclear Information System (INIS)
Dinpajooh, Mohammadhasan; Bai, Peng; Allan, Douglas A.; Siepmann, J. Ilja
2015-01-01
Since the seminal paper by Panagiotopoulos [Mol. Phys. 61, 813 (1997)], the Gibbs ensemble Monte Carlo (GEMC) method has been the most popular particle-based simulation approach for the computation of vapor–liquid phase equilibria. However, the validity of GEMC simulations in the near-critical region has been questioned because rigorous finite-size scaling approaches cannot be applied to simulations with fluctuating volume. Valleau [Mol. Simul. 29, 627 (2003)] has argued that GEMC simulations would lead to a spurious overestimation of the critical temperature. More recently, Patel et al. [J. Chem. Phys. 134, 024101 (2011)] opined that the use of analytical tail corrections would be problematic in the near-critical region. To address these issues, we perform extensive GEMC simulations for Lennard-Jones particles in the near-critical region varying the system size, the overall system density, and the cutoff distance. For a system with N = 5500 particles, potential truncation at 8σ and analytical tail corrections, an extrapolation of GEMC simulation data at temperatures in the range from 1.27 to 1.305 yields T c = 1.3128 ± 0.0016, ρ c = 0.316 ± 0.004, and p c = 0.1274 ± 0.0013 in excellent agreement with the thermodynamic limit determined by Potoff and Panagiotopoulos [J. Chem. Phys. 109, 10914 (1998)] using grand canonical Monte Carlo simulations and finite-size scaling. Critical properties estimated using GEMC simulations with different overall system densities (0.296 ≤ ρ t ≤ 0.336) agree to within the statistical uncertainties. For simulations with tail corrections, data obtained using r cut = 3.5σ yield T c and p c that are higher by 0.2% and 1.4% than simulations with r cut = 5 and 8σ but still with overlapping 95% confidence intervals. In contrast, GEMC simulations with a truncated and shifted potential show that r cut = 8σ is insufficient to obtain accurate results. Additional GEMC simulations for hard-core square-well particles with various
Patient satisfaction: focusing on "excellent".
Otani, Koichiro; Waterman, Brian; Faulkner, Kelly M; Boslaugh, Sarah; Burroughs, Thomas E; Dunagan, W Claiborne
2009-01-01
In an emerging competitive market such as healthcare, managers should focus on achieving excellent ratings to distinguish their organization from others. When it comes to customer loyalty, "excellent" has a different meaning. Customers who are merely satisfied often do not come back. The purpose of this study was to find out what influences adult patients to rate their overall experience as "excellent." The study used patient satisfaction data collected from one major academic hospital and four community hospitals. After conducting a multiple logistic regression analysis, certain attributes were shown to be more likely than others to influence patients to rate their experiences as excellent. The study revealed that staff care is the most influential attribute, followed by nursing care. These two attributes are distinctively stronger drivers of overall satisfaction than are the other attributes studied (i.e., physician care, admission process, room, and food). Staff care and nursing care are under the control of healthcare managers. If improvements are needed, they can be accomplished through training programs such as total quality management or continuous quality improvement, through which staff employees and nurses learn to be sensitive to patients' needs. Satisfying patients' needs is the first step toward having loyal patients, so hospitals that strive to ensure their patients are completely satisfied are more likely to prosper.
Leadership, excellence, creativity and innovation
Coulson-Thomas, Colin
2016-01-01
Raises questions about the meaning, purpose and practice of contemporary leadership in relation to excellence, creativity and innovation, covering leadership qualities, the context and requirements of leadership, leadership at different stages of development, creativity and innovation, CEOs and top down leadership, entrepreneurship and shared leadership, leading the network organisation, shared and collective leadership, the role and contribution of boards, key questions for boards, leadershi...
Managing Excellence in Sports Performance.
Lyle, John W. B.
1997-01-01
Conceptualizes excellence in sports performance and suggests that there is a failure to distinguish between community recreation and performance sports as well as lack of knowledge about talent identification. Proposes a structure for management and investment in education and training in the field. (SK)
Quality Management and Business Excellence
Directory of Open Access Journals (Sweden)
Vasile Dinu
2017-02-01
Full Text Available An excellent organization involves much more than the implementation and the certification of one or more models of management systems. It means developing techniques and tools of busin excellence which lead the organization to outstanding performance on quality, costs and deadlines in order to meet the expectations of all their stakeholders. Such an approach is needed especially in the context of an economy marked by globalization, extremely complex and dynamic that causes spectacular changes in the business environment by integrating quality management principles on purpose to develop sustainable excellence. Not coincidentally, the new edition of the European excellence model EFQM integrates for the first time the principle "managing with agility“ with the principles: “developing organizational capability”, “harnessing creativity & innovation”, “adding value to the customer”, “sustaining outstanding results” for the organization and “creating a sustainable future”. Also, the new model for quality management system defined by the edition from 2015 of ISO 9000 standards , promotes the process-based approach, incorporating the cycle "Plan - Do − Check − Act" (PDCA and the risk-based thinking, focusing on organizational change and innovation, in order to ensure a sustainable performance in business. Noteworthy is the endeavor for the development of a high-level structure for all international standards for management systems, aiming to harmonize these standards to facilitate the implementation of integrated management systems (quality − environment − security − social responsibility.
Understanding Research Excellence at IDRC
International Development Research Centre (IDRC) Digital Library (Canada)
KFerguson
2009-01-18
Jan 18, 2009 ... The primary intended users of this study are IDRC program staffand the ... type of framework, and some parameters that anchor the concepts.” ... (e.g., the complex health care delivery system), we have little reason to ..... defines or views research excellence and related concepts such as rigor and impact;.
Achieving excellence with limited resources
International Nuclear Information System (INIS)
Anson, L.W.; Spinney, R.W.
1985-01-01
The achievement of excellence in safety of nuclear power plant operation is dependent in part upon establishment of a performance-based training program. Developing such a program can be a laborious, time-consuming, and very expensive effort. Conducting job and task analyses, designing course outlines from learning objectives, developing training materials, evaluating program effectiveness and managing the training process and program through the out-years will exhaust any utility's training budget and staff. Because the achievement of excellence implies that training become in part performance-based, the question arises of how best to attain quality training yet still maintain a reasonable budget and staff workload. The answer lies not just in contracting the support necessary but making use of all available resources - training staff, contractor personnel in INPO
Microstructural characterization of EXCEL alloy
International Nuclear Information System (INIS)
Oroza Z E, Celiz; Saumell M, Lani; Versaci, R A; Bozzano, P B
2012-01-01
The microstructure of Excel alloy was studied by optical and scanning electron microscopy. X-ray diffraction was used to analyze the present phases. Characteristic peaks of α-Zr (HCP), β-Zr (BCC) and δhydride (FCC) were identified. The high relatives intensities of certain peaks suggest that samples are textured. Basal poles were dominant in radial-longitudinal planes and prismatic poles have the highest concentration in radial-tangential planes (author)
Customer satisfaction and business excellence
DEFF Research Database (Denmark)
Kristensen, Kai; Martensen, Anne; Grønholdt, Lars
The topic for this paper is the link between customer satisfaction and business performance, which makes it possible to use customer satisfaction measures as basis for creating business excellence. First, the paper presents microeconomic models for the relationship between customer satisfaction......, customer loyalty and performance, and optimal customer satisfaction is characterized which will help management choose the right quality parameters for improvement. Second, the paper describes empirical evidence that customer satisfaction measures, based on a modelling approach, have impact on economic...
Pinney, Rhiannon; Liverpool, Tanniemola B; Royall, C Patrick
2016-12-21
We consider a binary Lennard-Jones glassformer whose super-Arrhenius dynamics are correlated with the formation of particles organized into icosahedra under simple steady state shear. We recast this glassformer as an effective system of icosahedra [Pinney et al., J. Chem. Phys. 143, 244507 (2015)]. From the observed population of icosahedra in each steady state, we obtain an effective temperature which is linearly dependent on the shear rate in the range considered. Upon shear banding, the system separates into a region of high shear rate and a region of low shear rate. The effective temperatures obtained in each case show that the low shear regions correspond to a significantly lower temperature than the high shear regions. Taking a weighted average of the effective temperature of these regions (weight determined by region size) yields an estimate of the effective temperature which compares well with an effective temperature based on the global mesocluster population of the whole system.
Um modelo para a superfície líquida no estudo da dinâmica do espalhamento de Xe e Ne pelo esqualano
Directory of Open Access Journals (Sweden)
Leal Alexandre S.
2004-01-01
Full Text Available In this work we present a theoretical model to investigate the scattering of Xe and Ne by a liquid squalane surface. The liquid surface is modeled as a grid of harmonic oscillators with frequencies adjusted to experimental vibration as frequencies of the liquid squalane and the atom-surface interaction potential is modeled by a Lennard-Jones function. The three dimensional description of the dynamics of the process which occurs at the gas-liquid interface is obtained by the classical trajectory method. The general characteristics of the dynamics of the scattering process are in good agreement with experimental data.
DEFF Research Database (Denmark)
Toxværd, Søren
2016-01-01
temperature Ttr.p. crystallizes via a liquid droplet is an example of Ostwald's step rule. The homogeneous nucleation in the supersaturated gas is not to a crystal, but to a liquid-like critical nucleus. We have for the first time performed constant energy (NVE) Molecular Dynamics (MD) of homogeneous...... nucleation without the use of a thermostat. The simulations of homogeneous nucleation in a Lennard-Jones system from supersaturated vapor at temperatures below Ttr.p. reveals that the nucleation to a liquid-like critical nucleus is initiated by a small cold cluster [S. Toxvaerd, J. Chem. Phys. \\textbf{143...
Excellence through radiation protection practices
International Nuclear Information System (INIS)
Lee, D.A.; Armitage, G.; Popple, R.T.; Carrigan, J.T.
1987-01-01
The nuclear generation program at Ontario Hydro was initiated in the early 1960s. Over the last two decades the program has expanded to a planned capacity of ∼ 14,000 MW(electric) by 1992. Each of the nuclear stations consists of four identical reactor units and they range in size from 520 to 880 MW(electric). The overall objectives of Ontario Hydro's radiation protection program are stated as follows: (1) to prevent detrimental nonstochastic health effects to employees and the public; (2) to limit detrimental stochastic health effects occurring in employees or the public to levels as low as reasonably achievable (ALARA), social and economic factors being taken into account; and (3) to provide a level of health and safety that is as good as, or better than, comparable safe industries. Although many elements of the radiation protection program are similar to those adopted by other electrical utilities around the world, there are some unique features that have played an important part in the improvements achieved. These include: management commitment, design responsibility, radiation protection training, operations control, and work planning. The issues that need to be addressed in striving for overall excellence in radiological safety over the next decade are summarized
ITMO Photonics: center of excellence
Voznesenskaya, Anna; Bougrov, Vladislav; Kozlov, Sergey; Vasilev, Vladimir
2016-09-01
ITMO University, the leading Russian center in photonics research and education, has the mission to train highlyqualified competitive professionals able to act in conditions of fast-changing world. This paradigm is implemented through creation of a strategic academic unit ITMO Photonics, the center of excellence concentrating organizational, scientific, educational, financial, laboratory and human resources. This Center has the following features: dissemination of breakthrough scientific results in photonics such as advanced photonic materials, ultrafast optical and quantum information, laser physics, engineering and technologies, into undergraduate and graduate educational programs through including special modules into the curricula and considerable student's research and internships; transformation of the educational process in accordance with the best international educational practices, presence in the global education market in the form of joint educational programs with leading universities, i.e. those being included in the network programs of international scientific cooperation, and international accreditation of educational programs; development of mechanisms for the commercialization of innovative products - results of scientific research; securing financial sustainability of research in the field of photonics of informationcommunication systems via funding increase and the diversification of funding sources. Along with focusing on the research promotion, the Center is involved in science popularization through such projects as career guidance for high school students; interaction between student's chapters of international optical societies; invited lectures of World-famous experts in photonics; short educational programs in optics, photonics and light engineering for international students; contests, Olympics and grants for talented young researchers; social events; interactive demonstrations.
Excel for chemists: a comprehensive guide
National Research Council Canada - National Science Library
Billo, E. Joseph
2011-01-01
..., biological, and medicinal calculations. Including a CD-ROM for Windows, this new edition provides chemists and students with the a detailed guide to using the current versions of Excel (Excel 2007 and 2010...
Realisatie van Excel Kwadraat in de praktijk
Dijkstra, Elma
2013-01-01
Dijkstra, E. M. (2013, 2 July). Realisatie van Excel Kwadraat in de praktijk [Realization of Excellent Education in practice]. Presentation held at the OLK-meeting, ITS, Radboud University, Nijmegen, The Netherlands.
Rowlinson, J S; Baldwin, J E; Buckingham, A D; Danishefsky, S
2013-01-01
Liquids and Liquid Mixtures, Third Edition explores the equilibrium properties of liquids and liquid mixtures and relates them to the properties of the constituent molecules using the methods of statistical thermodynamics. Topics covered include the critical state, fluid mixtures at high pressures, and the statistical thermodynamics of fluids and mixtures. This book consists of eight chapters and begins with an overview of the liquid state and the thermodynamic properties of liquids and liquid mixtures, including vapor pressure and heat capacities. The discussion then turns to the thermodynami
IDRANAP - European Centre of Excellence
International Nuclear Information System (INIS)
Buzatu, Florin D.
2003-01-01
Selected by the European Commission (EC) experts out of 185 proposals from 11 countries, IDRANAP (Inter-Disciplinary Research and Applications based on Nuclear and Atomic Physics) is the only EC Centre of Excellence in nuclear physics. The project, initiated and developed by a remarkable team from our institute, researchers with a recognized international scientific level, has as main objectives: - promotion in Romania and in the region of modern applications derived from basic and applied research in nuclear and atomic physics; - disciplinary research in ecology, health, biology, science of materials; - specific nuclear and atomic physics research aimed to open new possibilities for applications; - to ensure stimulative conditions for PhD students from Romania and other EC candidate countries to improve their knowledge and experience by joining scientific activities in the region, a fact that might counteract their tendency to migrate to Western countries. The high scientific level of researchers, their access to national and international facilities as well as the link with prestigious laboratories abroad and the socio-economic demand motivated the development of the project. Among expected results, we mention: improving and spreading the scientific knowledge by publications; producing new facilities, devices and instruments; application of nuclear methods in industry, health-care and environment protection, and training of young researchers. The project consists of 18 workpackages structured in 5 distinct areas: - Determining environmental pollution; - Nuclear methods in biology and medicine; - Radionuclide metrology; - Analysis and characterization of materials; - Nuclei far from stability, decay modes, cosmic rays, and facilities.We make an up-to-date presentation of obtained results and activities performed within IDRANAP project, as well as a short overview of our institute. (author)
Teaching Excellence Initiatives: Modalities and Operational Factors
Land, Ray; Gordon, George
2015-01-01
Teaching excellence is at the centre of national and international higher education policy. The Higher Education Academy (HEA) is a part of the debate to develop a shared understanding of what constitutes teaching excellence and has published research including "Considering Teaching Excellence in Higher Education: 2007-2013" by Dr Vicky…
Density scaling and quasiuniversality of flow-event statistics for athermal plastic flows
DEFF Research Database (Denmark)
Lerner, Edan; Bailey, Nicholas; Dyre, J. C.
2014-01-01
Athermal steady-state plastic flows were simulated for the Kob-Andersen binary Lennard-Jones system and its repulsive version in which the sign of the attractive terms is changed to a plus. Properties evaluated include the distributions of energy drops, stress drops, and strain intervals between...... the flow events. We show that simulations at a single density in conjunction with an equilibrium-liquid simulation at the same density allow one to predict the plastic flow-event statistics at other densities. This is done by applying the recently established “hidden scale invariance” of simple liquids...
Characterization of the TIP4P-Ew water model: vapor pressure and boiling point.
Horn, Hans W; Swope, William C; Pitera, Jed W
2005-11-15
The liquid-vapor-phase equilibrium properties of the previously developed TIP4P-Ew water model have been studied using thermodynamic integration free-energy simulation techniques in the temperature range of 274-400 K. We stress that free-energy results from simulations need to be corrected in order to be compared to the experiment. This is due to the fact that the thermodynamic end states accessible through simulations correspond to fictitious substances (classical rigid liquids and classical rigid ideal gases) while experiments operate on real substances (liquids and real gases, with quantum effects). After applying analytical corrections the vapor pressure curve obtained from simulated free-energy changes is in excellent agreement with the experimental vapor pressure curve. The boiling point of TIP4P-Ew water under ambient pressure is found to be at 370.3+/-1.9 K, about 7 K higher than the boiling point of TIP4P water (363.7+/-5.1 K; from simulations that employ finite range treatment of electrostatic and Lennard-Jones interactions). This is in contrast to the approximately +15 K by which the temperature of the density maximum and the melting temperature of TIP4P-Ew are shifted relative to TIP4P, indicating that the temperature range over which the liquid phase of TIP4P-Ew is stable is narrower than that of TIP4P and resembles more that of real water. The quality of the vapor pressure results highlights the success of TIP4P-Ew in describing the energetic and entropic aspects of intermolecular interactions in liquid water.
Measuring research excellence in the EU
DEFF Research Database (Denmark)
Sørensen, Mads P.; Bloch, Carter Walter; Young, Mitchell
In 2013, the European Union unveiled its new ‘Composite Indicator for Scientific and Technological Research Excellence’, marking a turning point in how excellence is understood and used in European policy. This is not an isolated occurrence; policy-based interest in excellence is growing all over...... the world. The heightened focus on excellence and in particular, attempts to define it through quantitative indicators can have important implications for research policy and for the conduct of research itself. This paper examines how the European Union’s understanding of excellence has evolved in recent...... years, from the presentation of the Lisbon strategy in 2000 to the current Europe 2020 strategy. We find a distinct shift in the understanding of excellence and how success in the knowledge-based economy should be achieved: in the early period, excellence is a fuzzy concept, intrinsically embedded...
Time-dependent friction and solvation time correlation function
International Nuclear Information System (INIS)
Samanta, Alok; Ali, Sk Musharaf; Ghosh, Swapan K
2005-01-01
We have derived a new relation between the time-dependent friction and solvation time correlation function (STCF) for non-polar fluids. The friction values calculated using this relation and simulation results on STCF for a Lennard-Jones fluid are shown to have excellent agreement with the same obtained through mode-coupling theory. Also derived is a relation between the time-dependent dielectric friction and STCF for polar fluids. Routes are thus provided to obtain the time-dependent friction (non-polar as well as dielectric) from an experimentally measured quantity like STCF, even if the interparticle interaction potential is not known
Excel 2013 power programming with VBA
Walkenbach, John
2013-01-01
Maximize your Excel 2013 experience using VBA application development The new Excel 2013 boasts updated features, enhanced power, and new capabilities. Naturally, that means John Walkenbach returns with a new edition of his bestselling VBA Programming book and covers all the methods and tools you need to know in order to program with Excel. With this comprehensive guide, ""Mr. Spreadsheet"" shows you how to maximize your Excel experience using professional spreadsheet application development tips from his own personal bookshelf. Featuring a complete introduction to Visual Basic f
The Susquehanna plant lifetime excellence program
International Nuclear Information System (INIS)
McNamara, R.W.
1988-01-01
This paper discusses how the Susquehanna plant lifetime excellence program (SPLEX) blends many of the objectives of a new managing for excellence program with plant life extension objectives to achieve excellence in the lifetime operation and availability of the two-unit Susquehanna steam electric station. Investments in lifetime excellence improvements will provide near-term, as well as plant life extension, benefits. A high-quality lifetime experience record, together with extensive, periodic technical assessments and cost-benefit analyses, will provide conclusive justification for future extensions of the unit operating licenses
What every engineer should know about excel
Holman, J P
2006-01-01
INTRODUCTIONGetting the Most from ExcelConventionsOutline of MISCELLANEOUS OPERATIONS IN EXCEL AND WORDIntroductionPrint Screen or Screen DumpCustom Keyboard Setup for Symbols in WordViewing or Printing Column and Row Headings and Gridlines in ExcelAssorted InstructionsMoving Objects in Small Increments (Nudging)Formatting Objects in Word, Including WrappingFormatting Objects in ExcelUse of Photo-Editing Software in Word, Including WrappingCopying Cell Formulas: Effect of Relative and Absolute AddressesCopying Formulas by Dragging the Fill HandleShortcut for Changing the Status of Cell Address
Thinly disguised contempt: a barrier to excellence.
Brown-Stewart, P
1987-04-01
Many elements in contemporary leadership and management convey contempt for employees. "Thinly disguised contempt," a concept introduced by Peters and Austin in A Passion For Excellence, explains many barriers to the achievement of excellence in corporations across disciplines. Health care executives and managers can learn from the errors of corporate management and avoid replicating these errors in the health care industry.
The Pursuit of Excellence through Education.
Ferrari, Michel, Ed.
In this book theorists and researchers present a range of perspectives on how to promote excellence in education, providing an opportunity for expression to those who stress transformation of educational practice and those who emphasize individual abilities. In part 1, The Individual Pursuit of Excellence, the chapters are: (1) Learning from…
Using Microsoft Excel to Generate Usage Statistics
Spellman, Rosemary
2011-01-01
At the Libraries Service Center, statistics are generated on a monthly, quarterly, and yearly basis by using four Microsoft Excel workbooks. These statistics provide information about what materials are being requested and by whom. They also give details about why certain requests may not have been filled. Utilizing Excel allows for a shallower…
Phase equilibria of binary mixtures by molecular simulation and cubic equations of state
Directory of Open Access Journals (Sweden)
Cabral V.F.
2001-01-01
Full Text Available Molecular simulation data were used to study the performance of equations of state (EoS and combining rules usually employed in thermodynamic property calculations. The Monte Carlo method and the Gibbs ensemble technique were used for determining composition and densities of vapor and liquid phases in equilibrium for binary mixtures of Lennard-Jones fluids. Simulation results are compared to data in the literature and to those calculated by the t-PR-LJ EoS. The use of adequate combining rules has been shown to be very important for the satisfactory representation of molecular simulation data.
International Nuclear Information System (INIS)
Neimark, Alexander V; Ravikovitch, Peter I; Vishnyakov, Aleksey
2003-01-01
With the example of the capillary condensation of Lennard-Jones fluid in nanopores ranging from 1 to 10 nm, we show that the non-local density functional theory (NLDFT) with properly chosen parameters of intermolecular interactions bridges the scale gap from molecular simulations to macroscopic thermodynamics. On the one hand, NLDFT correctly approximates the results of Monte Carlo simulations (shift of vapour-liquid equilibrium, spinodals, density profiles, adsorption isotherms) for pores wider than about 2 nm. On the other hand, NLDFT smoothly merges (above 7-10 nm) with the Derjaguin-Broekhoff-de Boer equations which represent augmented Laplace-Kelvin equations of capillary condensation and desorption
People management as indicator of business excellence
DEFF Research Database (Denmark)
Haffer, Rafal; Kristensen, Kai
2010-01-01
Purpose – This paper aims to show the importance of people management as a key indicator of business excellence based on four research projects, conducted on the samples of Polish (in the years 2004-2005 and 2006-2007) and Danish companies (in 1999 and 2005). Design/methodology/approach – EFQM...... it possible to compare developing Polish and developed Danish companies in their initiatives aiming at business excellence. Findings – The results indicate significant negligence in the management of human resources as one of the initiatives towards business excellence of Polish enterprises before Poland...... Excellence Model indicators were used as the evaluation criteria for the studies. The data were next estimated as a structural equation model by partial least squares using SmartPLS software. That estimation was conducted on the model of the Danish Business Excellence Index methodology. Presented data make...
A polarizable QM/MM approach to the molecular dynamics of amide groups solvated in water
Energy Technology Data Exchange (ETDEWEB)
Schwörer, Magnus; Wichmann, Christoph; Tavan, Paul, E-mail: tavan@physik.uni-muenchen.de [Lehrstuhl für BioMolekulare Optik, Ludwig-Maximilians Universität München, Oettingenstr. 67, 80538 München (Germany)
2016-03-21
The infrared (IR) spectra of polypeptides are dominated by the so-called amide bands. Because they originate from the strongly polar and polarizable amide groups (AGs) making up the backbone, their spectral positions sensitively depend on the local electric fields. Aiming at accurate computations of these IR spectra by molecular dynamics (MD) simulations, which derive atomic forces from a hybrid quantum and molecular mechanics (QM/MM) Hamiltonian, here we consider the effects of solvation in bulk liquid water on the amide bands of the AG model compound N-methyl-acetamide (NMA). As QM approach to NMA we choose grid-based density functional theory (DFT). For the surrounding MM water, we develop, largely based on computations, a polarizable molecular mechanics (PMM) model potential called GP6P, which features six Gaussian electrostatic sources (one induced dipole, five static partial charge distributions) and, therefore, avoids spurious distortions of the DFT electron density in hybrid DFT/PMM simulations. Bulk liquid GP6P is shown to have favorable properties at the thermodynamic conditions of the parameterization and beyond. Lennard-Jones (LJ) parameters of the DFT fragment NMA are optimized by comparing radial distribution functions in the surrounding GP6P liquid with reference data obtained from a “first-principles” DFT-MD simulation. Finally, IR spectra of NMA in GP6P water are calculated from extended DFT/PMM-MD trajectories, in which the NMA is treated by three different DFT functionals (BP, BLYP, B3LYP). Method-specific frequency scaling factors are derived from DFT-MD simulations of isolated NMA. The DFT/PMM-MD simulations with GP6P and with the optimized LJ parameters then excellently predict the effects of aqueous solvation and deuteration observed in the IR spectra of NMA. As a result, the methods required to accurately compute such spectra by DFT/PMM-MD also for larger peptides in aqueous solution are now at hand.
Microsoft Office Excel 2003 Inside Out
Stinson, Craig
2003-01-01
Hey, you know your way around a spreadsheet-so now dig into Excel 2003 and really put your data to work! This supremely organized reference packs hundreds of timesaving solutions, troubleshooting tips, and handy workarounds in concise, fast-answer format. It's all muscle and no fluff. Discover the best and fastest ways to perform everyday tasks, and challenge yourself to new levels of Excel mastery! Build on what you already know about Excel and quickly dive into what's newLearn how the experts design more powerful spreadsheetsSharpen your core to advanced document editing and formatting skil
Tightly sealed facility of excellent in durability
International Nuclear Information System (INIS)
Shirano, Kenji; Chatani, Michio; Ebe, Shinji; Shimizu, Masatoshi; Seguchi, Tadao; Fukushima, Susumu; Hirata, Masaru; Shiosawa, Ken-ichi.
1992-01-01
It is found that a cross linked methacryl resin using an appropriate amount of a cross linking monomer also has a useful characteristic of an excellent chemical resistance and excellent γ-ray resistance. Then in the present invention, a cross linked methacryl resin molding product comprising 60 to 98 % by weight of methyl methacrylate units and 2 to 40 % by weight of cross linking monomer units is used as a material for transparent partition walls. A tightly sealed facility having the transparent partition wall materials of excellent radiation resistance in addition to acid resistance can be attained. (T.M.)
Statistical analysis with Excel for dummies
Schmuller, Joseph
2013-01-01
Take the mystery out of statistical terms and put Excel to work! If you need to create and interpret statistics in business or classroom settings, this easy-to-use guide is just what you need. It shows you how to use Excel's powerful tools for statistical analysis, even if you've never taken a course in statistics. Learn the meaning of terms like mean and median, margin of error, standard deviation, and permutations, and discover how to interpret the statistics of everyday life. You'll learn to use Excel formulas, charts, PivotTables, and other tools to make sense of everything fro
Alexander, Michael
2012-01-01
Save time and be more productive with this helpful guide to Excel macros! While most books about Excel macros offer only minor examples, usually aimed at illustrating a particular topic, this invaluable resource provides you with the tools needed to efficiently and effectively program Excel macros immediately. Step-by-step instructions show you how to create VBA macros and explain how to customize your applications to look and work exactly as you want them to. By the end of the book, you will understand how each featured macro works, be able to reuse the macros included in the book and online,
Lineær programmering med Excel
DEFF Research Database (Denmark)
Lynggaard, Peter
Publikationen giver en introduktion til faget "Lineær programmering". Formulering og løsning bygger på, at modellerne opstilles og løses i et Excel-regneark. Fremgangsmåden er forklaret trin for trin, således at hæftet kan bruges som selvstudiemateriale. Indholdsfortegnelse Generelt om styring og...... planlægning Lineær programmering Excel solveren Fortolkning af udskrifter Degeneration Excel tips Opgaver med løsninger...
Advanced Excel for scientific data analysis
De Levie, Robert
2004-01-01
Excel is by far the most widely distributed data analysis software but few users are aware of its full powers. Advanced Excel For Scientific Data Analysis takes off from where most books dealing with scientific applications of Excel end. It focuses on three areas-least squares, Fourier transformation, and digital simulation-and illustrates these with extensive examples, often taken from the literature. It also includes and describes a number of sample macros and functions to facilitate common data analysis tasks. These macros and functions are provided in uncompiled, computer-readable, easily
Excellence in the Knowledge-Based Economy: From Scientific to Research Excellence
Sørensen, Mads P.; Bloch, Carter; Young, Mitchell
2016-01-01
In 2013, the European Union (EU) unveiled its new "Composite Indicator for Scientific and Technological Research Excellence." This is not an isolated occurrence; policy-based interest in excellence is growing all over the world. The heightened focus on excellence and, in particular, attempts to define it through quantitative indicators…
Wood, Margaret; Su, Feng
2017-01-01
In the context of the Teaching Excellence Framework (TEF), we examine academics' perspectives on the discourse of "teaching excellence" based on an empirical study with 16 participants from five post-1992 universities. The article reports the findings on academics' views of the term and concept of "teaching excellence",…
Contribution of Lean Management to Excellence
Directory of Open Access Journals (Sweden)
López-Fresno Palmira
2014-11-01
Full Text Available To continuously and systematically improve efficiency and efficacy of processes, organizations need the implication of all employees in continuous improvement and innovation through suitable Quality Management Programs (QMPs. Effectiveness of these programs is directly linked to the requirement employees understand the methodologies and tools used for QM and the benefits that will derivate from their implementation, individually and collectively, so they can commit and implicate. Lean Management is a friendly methodology to continuously and systematically achieve process improvement, so helping the organization seeking operational excellence that contributes to overall excellence. This paper identifies Critical Success Factors (CSFs for an effective implementation of QMPs, suggests Lean Management as an easy-to-understand, powerful and friendly methodology for operational excellence and overall excellence, and presents a case experience of implementation of Lean Management in a health care organization that applies the EFQM model, and the lessons learnt.
Predictors of excellent response to lithium
DEFF Research Database (Denmark)
Kessing, Lars Vedel; Hellmund, Gunnar; Andersen, Per Kragh
2011-01-01
The aim of this study was to identify sociodemographic and clinical predictors of excellent response, that is, 'cure' of future affective episodes, to lithium in monotherapy. We used nationwide registers to identify all patients with a diagnosis of bipolar disorder in psychiatric hospital settings...... who were prescribed lithium from 1995 to 2006 in Denmark (N=3762). Excellent lithium responders were defined as patients who after a stabilization lithium start-up period of 6 months, continued lithium in monotherapy without getting hospitalized. The rate of excellent response to lithium...... with somatic comorbidity had increased rates of non-response to lithium compared with patients without somatic comorbidity (HR=1.23, 95% CI: 1.00-1.52).It is concluded that the prevalence of excellent response to lithium monotherapy is low and such patients are characterized by few earlier psychiatric...
Idea of Quality Versus Idea of Excellence
Directory of Open Access Journals (Sweden)
Marko Kiauta
2012-12-01
Full Text Available This study investigates professionals on the field of quality, are responsible to give to customer honest clarification of fundamental ideas. Quality movement is losing credibility with suggesting that the idea of quality is replacing with the idea of excellence. Findings are based on more than 25 years of practice in professional promotion of quality: in consulting on private and public sector, from 1990 lead auditor at SIQ (Slovenian Institute of Quality, from 1998 lead assessor – commission for Slovenian Excellence Quality Award. Theory is developed based on: Noriaki Kano theory of Attractive quality, Tito Conti ideas on TQM and applications problems of Excellence model, Practical case of General Hospital Novo Mesto (in 1998 first attempt of using EM, than forced to build QMS based on ISO 9001 and then returned to practice EM. Findings: We really need to amplify and to understand the concept of quality in a much wider way. To treat excellence related activities separated from all others quality management activities is not god solution. The name of EFQM Excellence Model should be replaced with Quality Management Model. Research limitations/implications: This paper present findings mainly based on practice in Slovenia and especially in public sector where practicing of CAF is not giving expected benefits. Practical implications: The three styles of quality management (improvements to reach demands, improvements to reach expectations, improvements to react on new conditions and needs should be connected with personal development. Theory is developed based on: Noriaki Kano theory of Attractive quality, Tito Conti ideas on TQM and applications problems of Excellence model. We need integration moments. Integration is other word for creativity and health. It leads to integrity. Excellence is only one of three states of quality. If we ask: How? The answer is bad, good or excellent. All three are possible states of the same parameter.
Solving rational expectations models using Excel
DEFF Research Database (Denmark)
Strulik, Holger
2004-01-01
Problems of discrete time optimal control can be solved using backward iteration and Microsoft Excel. The author explains the method in general and shows how the basic models of neoclassical growth and real business cycles are solved......Problems of discrete time optimal control can be solved using backward iteration and Microsoft Excel. The author explains the method in general and shows how the basic models of neoclassical growth and real business cycles are solved...
The Business Excellence Model for CSR Implementation?
DEFF Research Database (Denmark)
Neergaard, Peter; Gjerdrum Pedersen, Esben Rahbek
2012-01-01
Most of the Fortune 500 companies address Corporate Social Responsibility (CSR) on their websites. However, CSR remains a fluffy concept difficult to implement in organization. The European Business Excellence Model has since the introduction in 1992 served as a powerful tool for integrating...... European Award winning company has used the model to integrate CSR. The company adapted the Business Excellence model to improve performance, stimulate innovation and consensus....
Tanavalee, Chotetawan; Luksanapruksa, Panya; Singhatanadgige, Weerasak
2016-06-01
Microsoft Excel (MS Excel) is a commonly used program for data collection and statistical analysis in biomedical research. However, this program has many limitations, including fewer functions that can be used for analysis and a limited number of total cells compared with dedicated statistical programs. MS Excel cannot complete analyses with blank cells, and cells must be selected manually for analysis. In addition, it requires multiple steps of data transformation and formulas to plot survival analysis graphs, among others. The Megastat add-on program, which will be supported by MS Excel 2016 soon, would eliminate some limitations of using statistic formulas within MS Excel.
101 ready-to-use Excel formulas
Alexander, Michael
2014-01-01
Mr. Spreadsheet has done it again with 101 easy-to-apply Excel formulas 101 Ready-to-Use Excel Formulas is filled with the most commonly-used, real-world Excel formulas that can be repurposed and put into action, saving you time and increasing your productivity. Each segment of this book outlines a common business or analysis problem that needs to be solved and provides the actual Excel formulas to solve the problem-along with detailed explanation of how the formulas work. Written in a user-friendly style that relies on a tips and tricks approach, the book details how to perform everyday Excel tasks with confidence. 101 Ready-to-Use Excel Formulas is sure to become your well-thumbed reference to solve your workplace problems. The recipes in the book are structured to first present the problem, then provide the formula solution, and finally show how it works so that it can be customized to fit your needs. The companion website to the book allows readers to easily test the formulas and provides visual confirmat...
Directory of Open Access Journals (Sweden)
Ichiro Minami
2009-06-01
Full Text Available Current research on room-temperature ionic liquids as lubricants is described. Ionic liquids possess excellent properties such as non-volatility, non-flammability, and thermo-oxidative stability. The potential use of ionic liquids as lubricants was first proposed in 2001 and approximately 70 articles pertaining to fundamental research on ionic liquids have been published through May 2009. A large majority of the cations examined in this area are derived from 1,3-dialkylimidazolium, with a higher alkyl group on the imidazolium cation being beneficial for good lubrication, while it reduces the thermo-oxidative stability. Hydrophobic anions provide both good lubricity and significant thermo-oxidative stability. The anions decompose through a tribochemical reaction to generate metal fluoride on the rubbed surface. Additive technology to improve lubricity is also explained. An introduction to tribology as an interdisciplinary field of lubrication is also provided.
Minami, Ichiro
2009-06-24
Current research on room-temperature ionic liquids as lubricants is described. Ionic liquids possess excellent properties such as non-volatility, non-flammability, and thermo-oxidative stability. The potential use of ionic liquids as lubricants was first proposed in 2001 and approximately 70 articles pertaining to fundamental research on ionic liquids have been published through May 2009. A large majority of the cations examined in this area are derived from 1,3-dialkylimidazolium, with a higher alkyl group on the imidazolium cation being beneficial for good lubrication, while it reduces the thermo-oxidative stability. Hydrophobic anions provide both good lubricity and significant thermo-oxidative stability. The anions decompose through a tribochemical reaction to generate metal fluoride on the rubbed surface. Additive technology to improve lubricity is also explained. An introduction to tribology as an interdisciplinary field of lubrication is also provided.
Creating cultures of excellence: Strategies and outcomes
Directory of Open Access Journals (Sweden)
Michael Mintrom
2014-12-01
Full Text Available Research findings on effective support for learning, the development of expertise, and the psychology of success suggest that the pursuit of excellence is teachable. Within the emerging field of research and practice termed “the scholarship of teaching and learning,” considerable effort has been made to document the practices of teachers who, by various measures, have been deemed excellent. In contrast, no effort has been made to codify how students can be trained to self-consciously build behaviors that generate excellent outcomes. This article reports on a multi-year effort to create cultures of excellence among cohorts of graduate students. A statistical analysis of subsequent student performance on a significant, related task indicates that explicitly promoting a culture of excellence among course participants can have a positive and sustained impact on their individual practices. Comments from subsequent student reflections further support this claim. The teaching strategies reported here could be refined, replicated, and reinvented to good effect across higher education. They are also of special relevance to those delivering professional development training to early- and mid-career professionals.
Auto Draw from Excel Input Files
Strauss, Karl F.; Goullioud, Renaud; Cox, Brian; Grimes, James M.
2011-01-01
The design process often involves the use of Excel files during project development. To facilitate communications of the information in the Excel files, drawings are often generated. During the design process, the Excel files are updated often to reflect new input. The problem is that the drawings often lag the updates, often leading to confusion of the current state of the design. The use of this program allows visualization of complex data in a format that is more easily understandable than pages of numbers. Because the graphical output can be updated automatically, the manual labor of diagram drawing can be eliminated. The more frequent update of system diagrams can reduce confusion and reduce errors and is likely to uncover symmetric problems earlier in the design cycle, thus reducing rework and redesign.
Achieving engineering excellence at Palo Verde
International Nuclear Information System (INIS)
Prawlocki, F.C.
1989-01-01
Early in 1988, the management of the newly formed Palo Verde Nuclear Generating Station (PVNGS) Engineering and Construction Division was faced with a dilemma: how to build a competent, confident, efficient engineering organization in the face of increasing requirements and tightened fiscal controls. This paper discusses steps taken by Palo Verde to address actions taken to effect a smooth transition from construction to operations and the development of the Engineering Excellence Program. The Engineering Excellence Program will continue to evolve over time as the number of the NED's [Nuclear Engineering Department] personnel grown and processes are changed over the course of the next few years. As tasks from the Engineering Excellence Program action plan are completed, the results achieved are expected to be integrated into the routine business of the NED
Challenges to Business Excellence: Some Empirical Evidence
Directory of Open Access Journals (Sweden)
Brown Alan
2014-11-01
Full Text Available The business excellence models are used by many organisations around the world as a strategic driver for business improvement and in some cases as the basis for applications for awards based on the models. These include the Baldrige, EFQM, Australian Business Excellence Framework and many other national and regional models. Whilst many award recipients showcase their achievements, comparatively little is known about the challenges and impediments they face in reaching and sustaining high levels of success as evidenced by winning awards. This paper seeks to identify challenges faced by examining the experience of a sample of Australian Business Excellence Award winners. Findings suggest that the primary challenges include; leadership support, drive and consistency throughout the organisation and communicating strategy and making it meaningful for people at all levels. The study also found variability in challenges across organisations.
Excellence in the knowledge-based economy: from scientific to research excellence
DEFF Research Database (Denmark)
Sørensen, Mads P.; Bloch, Carter Walter; Young, Mitchell
2016-01-01
In 2013, the European Union (EU) unveiled its new ‘Composite Indicator for Scientific and Technological Research Excellence’. This is not an isolated occurrence; policy-based interest in excellence is growing all over the world. The heightened focus on excellence and, in particular, attempts...... to define it through quantitative indicators can have important implications for research policy and for the conduct of research itself. This paper examines how the EU's understanding of excellence has evolved in recent years, from the presentation of the Lisbon strategy in 2000 to the current Europe 2020...... strategy. We find a distinct shift in the understanding of excellence and how success in the knowledge-based economy should be achieved: in the early period, excellence is a fuzzy concept, intrinsically embedded in research and researchers and revealed by peer review. In the later period, excellence...
Excel formulas and functions for dummies
Bluttman, Ken
2013-01-01
Learn to use Excel for practical, day-to-day calculations Excel is a powerful program with more than 300 built-in functions that can be used to perform an almost infinite number of calculations. This friendly book shows you how to use the 150 most valuable ones in real-world situations: to compare the cost of buying vs. leasing a car, calculate classroom grades, or evaluate investment performance, for example. Another 85 specialized functions are also described. Detailed, step-by-step instructions help you understand how functions work within formulas and how you can use them t
Excellent fruits of national research and development
International Nuclear Information System (INIS)
2008-12-01
This book introduces 100 excellent fruits of research and development in Korea. Such as. It show the titles of 100 excellent fruits about technology of hope to give people healthy life, technology of product and abundance to enrich resource, technology to make green growth and sound society, next service technology to communicate with network, new electron technology to brings life change, technology to draw innovation of industrial fields, technology to build higher value-added product with new fusion materials and technology to share and to create future knowledge.
Critical self-evaluation for excellence
International Nuclear Information System (INIS)
Mullee, G.R.
1988-01-01
This paper discusses the use of critical self-evaluation of performance as a stimulus for excellence. Self-evaluation inherently provides acceptance and ownership of a problem, thereby motivating change. Some of the key elements of self-evaluation are discussed such as unbiased observations and appropriate performance standards. As circumstances change, an ongoing self-appraisal approach provides continuing feedback to maintain and further excellence. Two examples of critical self-evaluation in use at the Tennessee Valley Authority (TVA) are discussed
Confirmatory factor analysis using Microsoft Excel.
Miles, Jeremy N V
2005-11-01
This article presents a method for using Microsoft (MS) Excel for confirmatory factor analysis (CFA). CFA is often seen as an impenetrable technique, and thus, when it is taught, there is frequently little explanation of the mechanisms or underlying calculations. The aim of this article is to demonstrate that this is not the case; it is relatively straightforward to produce a spreadsheet in MS Excel that can carry out simple CFA. It is possible, with few or no programming skills, to effectively program a CFA analysis and, thus, to gain insight into the workings of the procedure.
Preparing data for analysis using microsoft Excel.
Elliott, Alan C; Hynan, Linda S; Reisch, Joan S; Smith, Janet P
2006-09-01
A critical component essential to good research is the accurate and efficient collection and preparation of data for analysis. Most medical researchers have little or no training in data management, often causing not only excessive time spent cleaning data but also a risk that the data set contains collection or recording errors. The implementation of simple guidelines based on techniques used by professional data management teams will save researchers time and money and result in a data set better suited to answer research questions. Because Microsoft Excel is often used by researchers to collect data, specific techniques that can be implemented in Excel are presented.
Energy Technology Data Exchange (ETDEWEB)
Mokhtari, B.; Enayati, M. [Iranian Offshore Oil Co., Tehran (Iran, Islamic Republic of); Heidaryan, E. [Islamic Azad Univ., Tehran (Iran, Islamic Republic of). Masjidosolayman Branch
2008-07-01
Theoretical methods show that crystalline hydrates can form from single-phase systems consisting of both vapor water with gaseous hydrate former and liquid water with dissolved hydrate former. Two phase systems consist of both liquid water with gaseous hydrate former and with liquid hydrate former on the surface. This paper presented a Langmuir constant related model for the prediction of equilibrium pressures and cage occupancies of pure component hydrates. Intermolecular potentials were fit to quantum mechanical energies to obtain the Langmuir constants, which differed from the procedure utilized with the vdWP model. The paper described the experimental method and model calculations. This included the Fugacity model and Van der Waals and Platteeuw model. The paper also discussed pair potential of non-spherical molecules, including the multicentre (site-site) potential; Gaussian overlap potential; Lennard-Jones potential; and Kihara generalized pair potential. It was concluded that fraction of occupied cavities is a function of pair potentials between hard core and empty hydrate lattice. These pair potentials could be calculated from some model as Kihara cell potential, Gaussian potential, Lennard-Jones potential and multicentre pair potential. 49 refs., 3 figs.
Enterprise-Wide Process & Performance Excellence:
DEFF Research Database (Denmark)
Edgeman, Rick; Kristensen, Kai; Eskildsen, Jacob Kjær
2013-01-01
Program value proposition, content, organization, and strategy are elaborated herein. This elaboration is the result of careful study of business and social trends, along with careful listening to collaborating enterprises. It is in this latter sense that the Enterprise-Wide Process & Performance...... Excellence certificate program is a product of a co-creation process....
Introduction to 3D Graphics through Excel
Benacka, Jan
2013-01-01
The article presents a method of explaining the principles of 3D graphics through making a revolvable and sizable orthographic parallel projection of cuboid in Excel. No programming is used. The method was tried in fourteen 90 minute lessons with 181 participants, which were Informatics teachers, undergraduates of Applied Informatics and gymnasium…
Using Excel in Teacher Education for Sustainability
Aydin, Serhat
2016-01-01
In this study, the feasibility of using Excel software in teaching whole Basic Statistics Course and its influence on the attitudes of pre-service science teachers towards statistics were investigated. One hundred and two pre-service science teachers in their second year participated in the study. The data were collected from the prospective…
Textbooks for Responsible Data Analysis in Excel
Garrett, Nathan
2015-01-01
With 27 million users, Excel (Microsoft Corporation, Seattle, WA) is the most common business data analysis software. However, audits show that almost all complex spreadsheets have errors. The author examined textbooks to understand why responsible data analysis is taught. A purposeful sample of 10 textbooks was coded, and then compared against…
Marketing and branding your Centers of Excellence.
Herrod, K G
2001-01-01
Branding your Centers of Excellence requires more than simply advertising. Developing a strong brand involves completing your due diligence. Adequate reparation and strategic planning will help your organization successfully navigate looming pitfalls, overcome competitive pressures, and make a direct hit with physicians and consumers.
Equilibrator: Modeling Chemical Equilibria with Excel
Vander Griend, Douglas A.
2011-01-01
Equilibrator is a Microsoft Excel program for learning about chemical equilibria through modeling, similar in function to EQS4WIN, which is no longer supported and does not work well with newer Windows operating systems. Similar to EQS4WIN, Equilibrator allows the user to define a system with temperature, initial moles, and then either total…
Centers of Excellence Contribution to Knowledge Augmentation
International Nuclear Information System (INIS)
Mignone, O.
2016-01-01
Full text: Knowledge management is a key need of the nuclear industry to cope with the knowledge limited augmentation and the risks of knowledge loss due to a number of reasons, such as: staff attrition, organizational changes, upgraded technologies, new projects implementation, and the nuclear power evolution in recent years (i.e., post-Fukushima upgrades). This document describes the contribution of nuclear centers of excellence to knowledge augmentation. The effective implementation of nuclear centers of excellence is a key success factor for the knowledge management programme of nuclear organizations. This document, is based on a real example of operating organization approach in launching such initiative for staff knowledge augmentation and performance improvement. Eventually, any type of organizations in the nuclear sector could apply the proposed technique to reach better knowledge usage. The nuclear centers of excellence are a key knowledge management initiative for the learning organizations that are caring about organizational intellectual capital and striving for performance improvement. The nuclear centers of excellence can be realized as a forum to exchange ideas, knowledge, information, experiences; to collect lessons learned; and to identify areas for improvement where further organizational competence building is needed. Usual realization of this initiative is going through an active staff involvement in knowledge sharing in a form of different technical communities of practice focusing on specific knowledge domains. (author
Key components when teaching for excellence
Wolfensberger, Marca; Wolfensberger, Marca; Drayer, Lyndsay; Volker, Judith
2014-01-01
The Research Centre for Talent Development in Higher Education and Society, based at Hanze University of Applied Sciences in the Netherlands, organised the first international conference “Evoking Excellence in Higher Education and Beyond”. This conference brought together scholars and educators from
Managing service excellence. Internal customer service training
International Nuclear Information System (INIS)
McAnulty, P.C.
1991-01-01
WHO ARE OUR CUSTOMERS? Electric Users, regulators, vendors, suppliers, or our own employees? The answer is ALL exclamation point They are all customers. Regardless if they are external or internal customers, one must focus on quality of service delivery in order to maintain customer satisfaction. The most successful companies are quickly realizing that managing SERVICE EX NCE is our only future. For the next decade, the issue of service quality will exceed the issue of productivity. It is very easy to see that the business behind a utility is serving our electric consumers. However, internal customer service - service excellence to employees inside a company is the foundation for success. This paper describes a training program that is being implemented across Duke Power for employees on internal customer service. How we provide service to each other within a company impacts service quality to our external customers. This training refocuses behaviors and perceptions so to concentrate on quality service delivery to our internal customers - our employees. We all have positive and negative experiences with obtaining quality service by either external organizations or internal employees. Therefore, we start with a common foundation. Whether it be a supplier, vendor, or a station administrative group, we have experienced either excellent or poor customer service. All of us have potential in managing the delivery of excellent customer service. However, many of us may need new perspectives so to add depth with which we view and manage service excellence to our internal customers
Electrical insulating liquid: A review
Directory of Open Access Journals (Sweden)
Deba Kumar Mahanta
2017-08-01
Full Text Available Insulating liquid plays an important role for the life span of the transformer. Petroleum-based mineral oil has become dominant insulating liquid of transformer for more than a century for its excellent dielectric and cooling properties. However, the usage of petroleum-based mineral oil, derived from a nonrenewable energy source, has affected the environment for its nonbiodegradability property. Therefore, researchers direct their attention to renewable and biodegradable alternatives. Palm fatty acid ester, coconut oil, sunflower oil, etc. are considered as alternatives to replace mineral oil as transformer insulation liquid. This paper gives an extensive review of different liquid insulating materials used in a transformer. Characterization of different liquids as an insulating material has been discussed. An attempt has been made to classify different insulating liquids-based on different properties.
Samuel P. Massie Chair of Excellence Program
Energy Technology Data Exchange (ETDEWEB)
Johnson, James H. [Howard Univ., Washington, DC (United States)
2014-12-01
Abstract In 1994 the Department of Energy established the DOE Chair of Excellence Professorship in Environmental Disciplines Program. In 2004, the Massie Chair of Excellence Professor at Howard University transitioned from Dr. Edward Martin to Dr. James H. Johnson, Jr. At the time of his appointment Dr. Johnson served as professor of civil engineering and Dean of the College of Engineering, Architecture and Computer Sciences. Program activities under Dr. Johnson were in the following areas: • Increase the institution’s capacity to conduct scientific research and technical investigations at the cutting-edge. • Promote interactions, collaborations and partnerships between the private sector, Federal agencies, majority research institutes and other HBCUs. • Assist other HBCUs in reaching parity in engineering and related fields. • Mentor young investigators and be a role model for students.
Excellent lubricating behavior of Brasenia schreberi mucilage.
Li, Jinjin; Liu, Yuhong; Luo, Jianbin; Liu, Pengxiao; Zhang, Chenhui
2012-05-22
The present work reports an excellent lubrication property of an aquatic plant called Brasenia schreberi (BS). To investigate the lubrication characteristics of the BS mucilage, a novel measuring system is designed, and an ultralow friction coefficient about 0.005 between the mucilage and glass surface has been obtained. It is found that the ultralow friction is closely related to the structure of mucilage and water molecules in the mucilage. The microstructure analysis indicates that the mucilage surrounding BS forms a kind of polysaccharide gel with many nanosheets. A possible lubrication mechanism is proposed that the formation of hydration layers among these polymer nanosheets with plenty of bonded water molecules causes the ultralow friction. The excellent lubrication property has a potential application for reducing the friction between a glossy pill coated with such layer of mucilage and people's throats.
The Business Excellence Model for CSR Implementation?
Directory of Open Access Journals (Sweden)
Neergaard Peter
2014-11-01
Full Text Available Most of the Fortune 500 companies address Corporate Social Responsibility (CSR on their websites. However, CSR remains a fluffy concept difficult to implement in organization. The European Business Excellence Model has since the introduction in 1992 served as a powerful tool for integrating quality in organizations. CSR was first introduced in the model in 2002. From 2004 the European Foundation for Quality Management (EFQM has been eager to promote the model as an effective tool for implementing CSR.. The article discusses the potentials of the model for this end and illustrates how a 2006 European Award winning company has used the model to integrate CSR. The company adapted the Business Excellence model to improve performance, stimulate innovation and consensus.
Discussion on 'Centres of excellence' in Africa
International Nuclear Information System (INIS)
Riad, S.
1999-01-01
In Africa, Centres of Excellence should be oriented to build up scientific and technological capacity in the four topics of international Monitoring System related technologies, namely, seismic monitoring, hydro acoustic monitoring, infrasound monitoring and radionuclides monitoring. Training programs on these topics should be a major objective. A network of such centres should be established in a number of African countries. Centres should be equipped with means and materials for on-line course dispatch to interested training centres or research institutions. African centres should develop strong relationship among themselves through information and data exchange and sharing, harmonization of training programs. National data centres may be established as a component of the African Centre of Excellence. States Signatories may authorize the establishment of a specific fund to support the activities of the African center
Leadership for Business Excellence: The Gender Perspective
DREW, EILEEN PATRICIA
2008-01-01
PUBLISHED The adoption of appropriate forms of leadership in response to modern organizational needs has become a major strand of management theory and underpins the pursuit of Total Quality/Business Excellence. With some notable exceptions, most of the leadership literature ignores the gender dimension of leadership This gender blindness and the association ofh management and leadership with men is being challenged through feminist/gender studies drawing upon ideas about po...
Surface Spectroscopy Center Of Excellence Project
Wooden, Diane
2014-01-01
We propose to develop a national center of excellence in Regolith Radiative Transfer (RRT), i.e., in modeling spectral reflectivity and emissivity of grainy or structured surfaces. The focus is the regime where the structural elements of grainy surfaces have grain sizes and separations of tens of microns, comparable to the wavelengths carrying diagnostic compositional information. This regime is of fundamental interest to remote sensing of planetary and terrestrial surfaces.
LICSS - a chemical spreadsheet in microsoft excel.
Lawson, Kevin R; Lawson, Jonty
2012-02-02
Representations of chemical datasets in spreadsheet format are important for ready data assimilation and manipulation. In addition to the normal spreadsheet facilities, chemical spreadsheets need to have visualisable chemical structures and data searchable by chemical as well as textual queries. Many such chemical spreadsheet tools are available, some operating in the familiar Microsoft Excel environment. However, within this group, the performance of Excel is often compromised, particularly in terms of the number of compounds which can usefully be stored on a sheet. LICSS is a lightweight chemical spreadsheet within Microsoft Excel for Windows. LICSS stores structures solely as Smiles strings. Chemical operations are carried out by calling Java code modules which use the CDK, JChemPaint and OPSIN libraries to provide cheminformatics functionality. Compounds in sheets or charts may be visualised (individually or en masse), and sheets may be searched by substructure or similarity. All the molecular descriptors available in CDK may be calculated for compounds (in batch or on-the-fly), and various cheminformatic operations such as fingerprint calculation, Sammon mapping, clustering and R group table creation may be carried out.We detail here the features of LICSS and how they are implemented. We also explain the design criteria, particularly in terms of potential corporate use, which led to this particular implementation. LICSS is an Excel-based chemical spreadsheet with a difference:• It can usefully be used on sheets containing hundreds of thousands of compounds; it doesn't compromise the normal performance of Microsoft Excel• It is designed to be installed and run in environments in which users do not have admin privileges; installation involves merely file copying, and sharing of LICSS sheets invokes automatic installation• It is free and extensibleLICSS is open source software and we hope sufficient detail is provided here to enable developers to add their
System Description: Embedding Verification into Microsoft Excel
Collins, Graham; Dennis, Louise Abigail
2000-01-01
The aim of the PROSPER project is to allow the embedding of existing verification technology into applications in such a way that the theorem proving is hidden, or presented to the end user in a natural way. This paper describes a system built to test whether the PROSPER toolkit satisfied this aim. The system combines the toolkit with Microsoft Excel, a popular commercial spreadsheet application.
Basic statistics with Microsoft Excel: a review.
Divisi, Duilio; Di Leonardo, Gabriella; Zaccagna, Gino; Crisci, Roberto
2017-06-01
The scientific world is enriched daily with new knowledge, due to new technologies and continuous discoveries. The mathematical functions explain the statistical concepts particularly those of mean, median and mode along with those of frequency and frequency distribution associated to histograms and graphical representations, determining elaborative processes on the basis of the spreadsheet operations. The aim of the study is to highlight the mathematical basis of statistical models that regulate the operation of spreadsheets in Microsoft Excel.
Role modeling excellence in clinical nursing practice.
Perry, R N Beth
2009-01-01
Role modeling excellence in clinical nursing practice is the focus of this paper. The phenomenological research study reported involved a group of 8 nurses identified by their colleagues as exemplary. The major theme revealed in this study was that these exemplary nurses were also excellent role models in the clinical setting. This paper details approaches used by these nurses that made them excellent role models. Specifically, the themes of attending to the little things, making connections, maintaining a light-hearted attitude, modeling, and affirming others are presented. These themes are discussed within the framework of Watson [Watson, J., 1989. Human caring and suffering: a subjective model for health services. In: Watson, J., Taylor, R. (Eds.), They Shall Not Hurt: Human Suffering and Human Caring. Colorado University, Boulder, CO] "transpersonal caring" and [Bandura, A., 1997. Social Learning Theory. Prentice Hall, Englewood Cliffs, NJ] "Social Learning Theory." Particular emphasis in the discussion is on how positive role modeling by exemplary practitioners can contribute to the education of clinical nurses in the practice setting.
Detergents - Zeolites and Enzymes Excel Cleaning Power
Indian Academy of Sciences (India)
oily soil was difficult to remove this way and remained attached to the fabric. ... Cationic. Quaternary ammonium .... (vi) have high liquid absorption capacities and (vii) free of legislative .... anti-corrosive agents and as lens cleaner;. (ii) in food ...
Professional excellence : defining learning outcomes for honours higher education
Fuller, Melissa; Robbe, Patricia; Wolfensberger, Marca
2016-01-01
Purpose Honours programs prepare talented students to become future excellent professionals . However, competences defining an excellent professional have not been elucidated yet. We investigated how professionals characterize an excellent communication professional, aiming to develop a competence
Tutorial: simulating chromatography with Microsoft Excel Macros.
Kadjo, Akinde; Dasgupta, Purnendu K
2013-04-22
Chromatography is one of the cornerstones of modern analytical chemistry; developing an instinctive feeling for how chromatography works will be invaluable to future generation of chromatographers. Specialized software programs exist that handle and manipulate chromatographic data; there are also some that simulate chromatograms. However, the algorithm details of such software are not transparent to a beginner. In contrast, how spreadsheet tools like Microsoft Excel™ work is well understood and the software is nearly universally available. We show that the simple repetition of an equilibration process at each plate (a spreadsheet row) followed by discrete movement of the mobile phase down by a row, easily automated by a subroutine (a "Macro" in Excel), readily simulates chromatography. The process is readily understood by a novice. Not only does this permit simulation of isocratic and simple single step gradient elution, linear or multistep gradients are also easily simulated. The versatility of a transparent and easily understandable computational platform further enables the simulation of complex but commonly encountered chromatographic scenarios such as the effects of nonlinear isotherms, active sites, column overloading, on-column analyte degradation, etc. These are not as easily simulated by available software. Views of the separation as it develops on the column and as it is seen by an end-column detector are both available in real time. Excel 2010™ also permits a 16-level (4-bit) color gradation of numerical values in a column/row; this permits visualization of a band migrating down the column, much as Tswett may have originally observed, but in a numerical domain. All parameters of relevance (partition constants, elution conditions, etc.) are readily changed so their effects can be examined. Illustrative Excel spreadsheets are given in the Supporting Information; these are easily modified by the user or the user can write his/her own routine. Copyright
Pursuit of excellence: A forgotten quest?
Directory of Open Access Journals (Sweden)
Mark B Wertheimer
2018-01-01
Full Text Available The article explores the current orthodontic landscape with respect to the challenges that affect the pursuit of excellence in the specialty. These challenges include marketing by manufacturing companies, financial pressures, marketplace competition, attaining practice efficiency, new product introduction with limited supporting evidence, attributing greater importance to patient experience than the best approach to treatment, and lack of public education regarding their best interests. Home or DIY treatment, bypassing office visits and the practitioner, have also emerged as a concerning trend with the public not clearly understanding the detrimental consequences that may ensue. An over reliance on technology may override individualized treatment and further compromise treatment results.
The behaviour of hydrogen in Excel alloy
Energy Technology Data Exchange (ETDEWEB)
Ells, C.E. [Atomic Energy of Canada Ltd., Chalk River, ON (Canada). Chalk River Nuclear Labs.; Coleman, C.E. [Atomic Energy of Canada Ltd., Chalk River, ON (Canada). Chalk River Nuclear Labs.; Cheadle, B.A. [Atomic Energy of Canada Ltd., Chalk River, ON (Canada). Chalk River Nuclear Labs.; Sagat, S. [Atomic Energy of Canada Ltd., Chalk River, ON (Canada). Chalk River Nuclear Labs.; Rodgers, D.K. [Atomic Energy of Canada Ltd., Chalk River, ON (Canada). Chalk River Nuclear Labs.
1995-12-15
To enable mitigation of deleterious effects from hydride on the mechanical behaviour of Excel alloy, Zr-3.5 wt.% Sn-0.8 wt.% Mo-0.8 wt.% Nb, the behaviours of hydrogen and hydride in the alloy have been studied. Properties of interest are the terminal solid solubility, diffusivity, heat of transport, stress reorientation, and the initiation and crack growth of delayed hydride cracking. The results obtained are compared with those of other zirconium-rich alloys, notably Zr-2.5 wt.% Nb. (orig.)
Self-scheduling with Microsoft Excel.
Irvin, S A; Brown, H N
1999-01-01
Excessive time was being spent by the emergency department (ED) staff, head nurse, and unit secretary on a complex 6-week manual self-scheduling system. This issue, plus inevitable errors and staff dissatisfaction, resulted in a manager-lead initiative to automate elements of the scheduling process using Microsoft Excel. The implementation of this initiative included: common coding of all 8-hour and 12-hour shifts, with each 4-hour period represented by a cell; the creation of a 6-week master schedule using the "count-if" function of Excel based on current staffing guidelines; staff time-off requests then entered by the department secretary; the head nurse, with staff input, then fine-tuned the schedule to provide even unit coverage. Outcomes of these changes included an increase in staff satisfaction, time saved by the head nurse, and staff work time saved because there was less arguing about the schedule. Ultimately, the automated self-scheduling method was expanded to the entire 700-bed hospital.
Collins, Jim
2012-01-01
Dix ans après le succès mondial de De la performance à l'excellence (Good to Great), Jim Collins et son associé Morten T. Hansen s'interrogent ici sur la nature de l excellence en période d incertitude. Pourquoi, dans un contexte chaotique, certaines entreprises sont florissantes et d autres non ? Comment, en ces temps troublés, réussir à diriger et vaincre l adversité pour dominer son marché ? La chance peut-elle sérieusement être envisagée comme un facteur de réussite ? À l issue d un programme de recherche ambitieux et rigoureux qui a duré neuf ans, les auteurs exposent dans cet ouvrage les nouveaux principes pour bâtir une entreprise réellement excellente. Leurs conclusions sont, comme toujours, étonnantes. Ils soulignent notamment que la course à l innovation n est pas toujours la meilleure voie à suivre, que discipline et créativité peuvent aller de concert et que malgré le changement permanent, les meilleures décisions sont rarement prises dans l urgence. Quant aux leaders, on...
Yuhara, Daisuke; Brumby, Paul E.; Wu, David T.; Sum, Amadeu K.; Yasuoka, Kenji
2018-05-01
To develop prediction methods of three-phase equilibrium (coexistence) conditions of methane hydrate by molecular simulations, we examined the use of NVT (isometric-isothermal) molecular dynamics (MD) simulations. NVT MD simulations of coexisting solid hydrate, liquid water, and vapor methane phases were performed at four different temperatures, namely, 285, 290, 295, and 300 K. NVT simulations do not require complex pressure control schemes in multi-phase systems, and the growth or dissociation of the hydrate phase can lead to significant pressure changes in the approach toward equilibrium conditions. We found that the calculated equilibrium pressures tended to be higher than those reported by previous NPT (isobaric-isothermal) simulation studies using the same water model. The deviations of equilibrium conditions from previous simulation studies are mainly attributable to the employed calculation methods of pressure and Lennard-Jones interactions. We monitored the pressure in the methane phase, far from the interfaces with other phases, and confirmed that it was higher than the total pressure of the system calculated by previous studies. This fact clearly highlights the difficulties associated with the pressure calculation and control for multi-phase systems. The treatment of Lennard-Jones interactions without tail corrections in MD simulations also contributes to the overestimation of equilibrium pressure. Although improvements are still required to obtain accurate equilibrium conditions, NVT MD simulations exhibit potential for the prediction of equilibrium conditions of multi-phase systems.
Divergence of activity expansions: Is it actually a problem?
Ushcats, M. V.; Bulavin, L. A.; Sysoev, V. M.; Ushcats, S. Yu.
2017-12-01
For realistic interaction models, which include both molecular attraction and repulsion (e.g., Lennard-Jones, modified Lennard-Jones, Morse, and square-well potentials), the asymptotic behavior of the virial expansions for pressure and density in powers of activity has been studied taking power terms of high orders into account on the basis of the known finite-order irreducible integrals as well as the recent approximations of infinite irreducible series. Even in the divergence region (at subcritical temperatures), this behavior stays thermodynamically adequate (in contrast to the behavior of the virial equation of state with the same set of irreducible integrals) and corresponds to the beginning of the first-order phase transition: the divergence yields the jump (discontinuity) in density at constant pressure and chemical potential. In general, it provides a statistical explanation of the condensation phenomenon, but for liquid or solid states, the physically proper description (which can turn the infinite discontinuity into a finite jump of density) still needs further study of high-order cluster integrals and, especially, their real dependence on the system volume (density).
Droplet spreading driven by van der Waals force: a molecular dynamics study
Wu, Congmin
2010-07-07
The dynamics of droplet spreading is investigated by molecular dynamics simulations for two immiscible fluids of equal density and viscosity. All the molecular interactions are modeled by truncated Lennard-Jones potentials and a long-range van der Waals force is introduced to act on the wetting fluid. By gradually increasing the coupling constant in the attractive van der Waals interaction between the wetting fluid and the substrate, we observe a transition in the initial stage of spreading. There exists a critical value of the coupling constant, above which the spreading is pioneered by a precursor film. In particular, the dynamically determined critical value quantitatively agrees with that determined by the energy criterion that the spreading coefficient equals zero. The latter separates partial wetting from complete wetting. In the regime of complete wetting, the radius of the spreading droplet varies with time as R(t) ∼ √t, a behavior also found in molecular dynamics simulations where the wetting dynamics is driven by the short-range Lennard-Jones interaction between liquid and solid. © 2010 IOP Publishing Ltd.
Yuhara, Daisuke; Brumby, Paul E; Wu, David T; Sum, Amadeu K; Yasuoka, Kenji
2018-05-14
To develop prediction methods of three-phase equilibrium (coexistence) conditions of methane hydrate by molecular simulations, we examined the use of NVT (isometric-isothermal) molecular dynamics (MD) simulations. NVT MD simulations of coexisting solid hydrate, liquid water, and vapor methane phases were performed at four different temperatures, namely, 285, 290, 295, and 300 K. NVT simulations do not require complex pressure control schemes in multi-phase systems, and the growth or dissociation of the hydrate phase can lead to significant pressure changes in the approach toward equilibrium conditions. We found that the calculated equilibrium pressures tended to be higher than those reported by previous NPT (isobaric-isothermal) simulation studies using the same water model. The deviations of equilibrium conditions from previous simulation studies are mainly attributable to the employed calculation methods of pressure and Lennard-Jones interactions. We monitored the pressure in the methane phase, far from the interfaces with other phases, and confirmed that it was higher than the total pressure of the system calculated by previous studies. This fact clearly highlights the difficulties associated with the pressure calculation and control for multi-phase systems. The treatment of Lennard-Jones interactions without tail corrections in MD simulations also contributes to the overestimation of equilibrium pressure. Although improvements are still required to obtain accurate equilibrium conditions, NVT MD simulations exhibit potential for the prediction of equilibrium conditions of multi-phase systems.
Discrimination against Women as a Subtext of Excellence.
Watson, Scott B.
1993-01-01
Pursuing excellence in sport discriminates against women. Alongside the primary texts of the glories of excellence runs a subtext of inequality and discrimination. The paper traces the idea of sport as a quest for excellence through various interpretations of the meaning of sport, discussing excellence as a socially constructed concept. (SM)
A national neurological excellence centers network.
Pazzi, S; Cristiani, P; Cavallini, A
1998-02-01
The most relevant problems related to the management of neurological disorders are (i) the frequent hospitalization in nonspecialist departments, with the need for neurological consultation, and (ii) the frequent requests of GPs for highly specialized investigations that are very expensive and of little value in arriving at a correct diagnosis. In 1996, the Consorzio di Bioingegneria e Informatica Medica in Italy realized the CISNet project (in collaboration with the Consorzio Istituti Scientifici Neuroscienze e Tecnologie Biomediche and funded by the Centro Studi of the National Public Health Council) for the implementation of a national neurological excellence centers network (CISNet). In the CISNet project, neurologists will be able to give on-line interactive consultation and off-line consulting services identifying correct diagnostic/therapeutic procedures, evaluating the need for both examination in specialist centers and admission to specialized centers, and identifying the most appropriate ones.
Guaranteeing CERN’s excellence: consolidate experience
Staff Association
2014-01-01
For its missions CERN requires staff with solid experience in all its domains of activity The Organization has several missions: fundamental research, technical developments and innovation, training the several hundreds of associates, fellows and students, while at the same time taking care of more than 10000 users. In order to guarantee excellence in all of these areas, CERN has to put in place an efficient personnel policy. Such a policy must allow the Organization to recruit collaborators with the highest competence from all Member States, and to keep and motivate them during their entire professional career. But, more importantly, the Organization has to be able to count on a stable workforce. It needs staff with experience gained over a long period in the fields of accelerators, detectors, and operating procedures, if it is to fulfil successfully its important mission of training and knowledge transfer, which is very much appreciated by our Member states, since it highlights a visible return on invest...
BREEAM Excellent: Business Value Vs Employee Morale
Turner, Nova; Arif, Mohammed
2012-05-01
BREEAM is gaining popularity in the UK. Similar green building standards have gained popularity worldwide. However, it is important that we analyse the actual value added to a business by having a BREEAM rated facility. It is also important to analyze the impact on employee performance of such a facility. This paper presents a case study of a BREEAM excellent rated building with impact on the morale and performance of the employees. The data for the paper was collected using semi-structured interviews of a group of employees who work at this facility located in Glasgow. The results suggest that it is important to highlight the tangible benefits and value added through the implementation of the BREEAM standard.
Data analysis for physical scientists featuring Excel
Kirkup, Les
2012-01-01
The ability to summarise data, compare models and apply computer-based analysis tools are vital skills necessary for studying and working in the physical sciences. This textbook supports undergraduate students as they develop and enhance these skills. Introducing data analysis techniques, this textbook pays particular attention to the internationally recognised guidelines for calculating and expressing measurement uncertainty. This new edition has been revised to incorporate Excel® 2010. It also provides a practical approach to fitting models to data using non-linear least squares, a powerful technique which can be applied to many types of model. Worked examples using actual experimental data help students understand how the calculations apply to real situations. Over 200 in-text exercises and end-of-chapter problems give students the opportunity to use the techniques themselves and gain confidence in applying them. Answers to the exercises and problems are given at the end of the book.
Business excellence journey in countries in transition
Directory of Open Access Journals (Sweden)
Pavel Castka
2001-01-01
Full Text Available This paper describes the journey toward business excellence regarding the influence of the contemporary global environment, as well as the specifics of the environment in countries in transition (the environment in the Czech Republic is taken as a representative model. Closer focus is given on problems connected with productivity, effectivity, innovation, quality and certification, use of IT/IS and on problems with participation of employees. The abovementioned characteristics make up the goals of a change to a process-oriented company. In regard of business downturn in many companies in the post-communist environment, these goals are achievable by radical change using the ideas of Business Process Reengineering (BPR and the process-oriented model described at the end of this paper.
Achieving excellence on shift through teamwork
International Nuclear Information System (INIS)
Newman, L.
1988-01-01
Anyone familiar with the nuclear industry realizes the importance of operators. Operators can achieve error-free plant operations, i.e., excellence on shift through teamwork. As a shift supervisor (senior reactor operator/shift technical advisor) the author went through the plant's first cycle of operations with no scrams and no equipment damaged by operator error, having since changed roles (and companies) to one of assessing plant operations. This change has provided the opportunity to see objectively the importance of operators working together and of the team building and teamwork that contribute to the shift's success. This paper uses examples to show the effectiveness of working together and outlines steps for building a group of operators into a team
Aluminum alloy excellent in neutron absorbing performance
International Nuclear Information System (INIS)
Iida, Tetsuya; Tamamura, Tadao; Morimoto, Hiroyuki; Ouchi, Ken-ichiro.
1987-01-01
Purpose: To obtain structural materials made of aluminum alloys having favorable neutron absorbing performance and excellent in the performance as structural materials such as processability and strength. Constitution: Powder of Gd 2 O 3 as a gadolinium compound or metal gadolinium is uniformly mixed with the powder of aluminum or aluminum alloy. The amount of the gadolinium compound added is set to 0.1 - 30 % by weight. No sufficient neutron absorbing performance can be obtained if it is less than 0.1 % by weight, whereas the processability and mechanical property of the alloy are degraded if it exceeds 30 % by weight. Further, the grain size is set to less about 50 μm. Further, since the neutron absorbing performance varies greatly if the aluminum powder size exceeds 100 μm, the diameter is set to less than about 100 μm. These mixtures are molded in a hot press. This enables to obtain aimed structural materials. (Takahashi, M.)
Pension fund excellence creating value for stakeholders
Ambachtsheer, Keith P.
1998-01-01
Internationally recognized experts in the field introduce their "business excellence paradigm". In this book, two leading pension fund experts lay out a comprehensive plan for effective fund management. With the help of domestic and global case studies they critically assess current approaches to pension fund management and isolate what works and what doesn't using their unique critically acclaimed "run-it-like-a-business" model. Keith P. Ambachtsheer (Toronto, Canada) is principle at KPA Advisory Service, Inc., a pension fund management consulting firm. He runs The Ambachtsheer Letter and cofounded Cost Effective Measurement, Inc., which monitors the performance of 300 of the world's largest asset funds. D. Don Ezra (Toronto, Canada) is Director of European Consulting at Frank Russell Co. His previous books include The Struggle for Pension Fund Wealth.
Excel spreadsheet in teaching numerical methods
Djamila, Harimi
2017-09-01
One of the important objectives in teaching numerical methods for undergraduates’ students is to bring into the comprehension of numerical methods algorithms. Although, manual calculation is important in understanding the procedure, it is time consuming and prone to error. This is specifically the case when considering the iteration procedure used in many numerical methods. Currently, many commercial programs are useful in teaching numerical methods such as Matlab, Maple, and Mathematica. These are usually not user-friendly by the uninitiated. Excel spreadsheet offers an initial level of programming, which it can be used either in or off campus. The students will not be distracted with writing codes. It must be emphasized that general commercial software is required to be introduced later to more elaborated questions. This article aims to report on a teaching numerical methods strategy for undergraduates engineering programs. It is directed to students, lecturers and researchers in engineering field.
The European network of excellence Emil
International Nuclear Information System (INIS)
2006-01-01
The network of excellence EMIL (European Molecular Imaging Laboratories ) is the only European network of excellence in molecular imaging for oncology. It was set up and is coordinated by the 'in vivo imaging of gene expression' group of CEA Orsay. Included in Priority Thematic Area 1 (life sciences, genomics and biotechnology for health) of the European Commission's 6. Framework Programme for Research and Technological Development (FP6), this five-year project (2004-2009) aims t o merge the leading European research teams in molecular imaging, in universities, research centres and small and medium enterprises, to focus on early diagnosis, prognosis and therapeutic evaluation of cancer. The EMIL network brings together 58 partners representing 43 bodies in 13 European countries, and integrates 6 technological facilities: Orsay (France), Turin (Italy), Cologne (Germany), Leiden (Netherlands), Milan (Italy) and Antwerpen (Belgium).The research and training activities of the EMIL network are based on 9 thematic working groups or 'work packages' (wp), forming a common activity programme including : Integration activities: creation of a network of technological and training facilities favouring the mobility of researchers and the integration of small and medium enterprises into the EMIL network. Dissemination of expertise activities: training, communication, common knowledge management and intellectual property rights. Research activities: a common research programme with a horizontal dimension, making use of methodological tools of physics, biology and chemistry necessary for the further development of molecular imaging (instrument techniques, molecular probes, biological engineering), and a vertical integrative dimension, bringing together cancer imaging applications (early diagnostic imaging, development of new therapies imaging for drug development). (author)
The European network of excellence Emil
Energy Technology Data Exchange (ETDEWEB)
NONE
2006-07-01
The network of excellence EMIL (European Molecular Imaging Laboratories ) is the only European network of excellence in molecular imaging for oncology. It was set up and is coordinated by the 'in vivo imaging of gene expression' group of CEA Orsay. Included in Priority Thematic Area 1 (life sciences, genomics and biotechnology for health) of the European Commission's 6. Framework Programme for Research and Technological Development (FP6), this five-year project (2004-2009) aims t o merge the leading European research teams in molecular imaging, in universities, research centres and small and medium enterprises, to focus on early diagnosis, prognosis and therapeutic evaluation of cancer. The EMIL network brings together 58 partners representing 43 bodies in 13 European countries, and integrates 6 technological facilities: Orsay (France), Turin (Italy), Cologne (Germany), Leiden (Netherlands), Milan (Italy) and Antwerpen (Belgium).The research and training activities of the EMIL network are based on 9 thematic working groups or 'work packages' (wp), forming a common activity programme including : Integration activities: creation of a network of technological and training facilities favouring the mobility of researchers and the integration of small and medium enterprises into the EMIL network. Dissemination of expertise activities: training, communication, common knowledge management and intellectual property rights. Research activities: a common research programme with a horizontal dimension, making use of methodological tools of physics, biology and chemistry necessary for the further development of molecular imaging (instrument techniques, molecular probes, biological engineering), and a vertical integrative dimension, bringing together cancer imaging applications (early diagnostic imaging, development of new therapies imaging for drug development). (author)
Soluble, Exfoliated Two-Dimensional Nanosheets as Excellent Aqueous Lubricants.
Zhang, Wenling; Cao, Yanlin; Tian, Pengyi; Guo, Fei; Tian, Yu; Zheng, Wen; Ji, Xuqiang; Liu, Jingquan
2016-11-30
Dispersion in water of two-dimensional (2D) nanosheets is conducive to their practical applications in fundamental science communities due to their abundance, low cost, and ecofriendliness. However, it is difficult to achieve stable aqueous 2D material suspensions because of the intrinsic hydrophobic properties of the layered materials. Here, we report an effective and economic way of producing various 2D nanosheets (h-BN, MoS 2 , MoSe 2 , WS 2 , and graphene) as aqueous dispersions using carbon quantum dots (CQDs) as exfoliation agents and stabilizers. The dispersion was prepared through a liquid phase exfoliation. The as-synthesized stable 2D nanosheets based dispersions were characterized by UV-vis, HRTEM, AFM, Raman, XPS, and XRD. The solutions based on CQD decorated 2D nanosheets were utilized as aqueous lubricants, which realized a friction coefficient as low as 0.02 and even achieved a superlubricity under certain working conditions. The excellent lubricating properties were attributed to the synergetic effects of the 2D nanosheets and CQDs, such as good dispersion stability and easy-sliding interlayer structure. This work thus proposes a novel strategy for the design and preparation of high-performance water based green lubricants.
Excel 2010 all-in-one for dummies
Harvey, Greg
2010-01-01
A comprehensive, up-to-date, user-friendly guide to Excel 2010 Excel is the standard for spreadsheet applications and is used worldwide, but it's not always user-friendly. That makes it a perfect For Dummies topic, and this handy all-in-one guide covers all the essentials, the new features, how to analyze data with Excel, and much more. Eight minibooks address Excel basics, worksheet design, formulas and functions, worksheet collaboration and review, charts and graphics, data management, data analysis, and Excel and VBA.Excel is the leading spreadsheet/data analysis s
CERN, a laboratory of social excellence
Staff Association
2012-01-01
The HR 2012 Forum, where Human Resources (HR) professionals meet and present innovative services and tools in the HR sector, was held on 3rd and 4th October at Palexpo, Geneva. CERN won the 3rd HR Innovation Award for the Long-Term Saved Leave Scheme (LTSLS) for its novelty and innovation. The award was presented to Jean-Marc Saint Viteux, Deputy-Head of HR Department. This is excellent news for our Organization. One can say that the Long-Term Saved Leave Scheme (LTSLS) originated from proposals by the Staff Association in 1996, based on general considerations on a framework for flexible working time arrangements. This article recalls the history of our work on this topic, which resulted in the implementation of PRP and various variants of a saved leave scheme. In a future issue of Echo, we will come back on other elements of CERN's social policy that we would like to improve upon to ensure a better work-life balance. Indeed, a good employer must offer a working environment that allows an...
Beyond accreditation: excellence in medical education.
Ahn, Eusang; Ahn, Ducksun
2014-01-01
Medical school accreditation is a relatively new phenomenon in Korea. The development of an accreditation body and standards for a two-tiered "Must" and "Should" system in 1997 eventually led to the implementation of a third "Excellence" level of attainment. These standards were conceived out of a desire to be able to first recognize and promote outstanding performance of medical schools, second to provide role models in medical education, and furthermore to preview the third level as potential components of the pre-existing second level for the next accreditation cycle. It is a quality-assurance mechanism that, while not required for accreditation itself, pushes medical schools to go beyond the traditional requirements of mere pass-or-fail accreditation adequacy, and encourages schools to deliver an unprecedented level of medical education. The Association for Medical Education in Europe developed its own third-tier system of evaluation under the ASPIRE project, with many similar goals. Due to its advanced nature and global scope, the Korean accreditation body has decided to implement the ASPIRE system in Korea as well.
Firm characteristics and excellence in integrated reporting
Directory of Open Access Journals (Sweden)
Natasha Buitendag
2017-02-01
Full Text Available Background: Integrated reporting has attracted much attention in the past few years, and South Africa has taken the lead in its development worldwide. An annual survey is published by Ernst & Young regarding the quality of the integrated reports of the top 100 entities listed on the Johannesburg Stock Exchange (JSE. Aim: The study on which this article is based was aimed at determining whether the assessment of an entity’s characteristics can predetermine the quality of the integrated report generated by that entity. Setting: This article focuses on an analysis of the integrated reporting of the top 100 entities listed on JSE for the financial years ending in 2013, 2014 and 2015. Methods: Comparison of categorical variables, mixed-model repeated measures ANOVA and generalised estimating equations were applied to identify the best classificators to distinguish between excellent integrated reporting and those reports where progress could still be made. Results: The results show that the type of industry the entity finds itself in, the size and profitability of the entity, as well as the composition of the members of the board, have an effect on the quality of the integrated report. Conclusion: Our results indicated that the type of industry, size of an entity, the profitability and composition of the board of directors, all have an effect on the quality of the integrated reporting. Our evidence will assist current and prospective stakeholders in evaluating the expected quality of an entity’s integrated report, through the evaluation of certain firm characteristics.
LIQUID-LIQUID EXTRACTION COLUMNS
Thornton, J.D.
1957-12-31
This patent relates to liquid-liquid extraction columns having a means for pulsing the liquid in the column to give it an oscillatory up and down movement, and consists of a packed column, an inlet pipe for the dispersed liquid phase and an outlet pipe for the continuous liquid phase located in the direct communication with the liquid in the lower part of said column, an inlet pipe for the continuous liquid phase and an outlet pipe for the dispersed liquid phase located in direct communication with the liquid in the upper part of said column, a tube having one end communicating with liquid in the lower part of said column and having its upper end located above the level of said outlet pipe for the dispersed phase, and a piston and cylinder connected to the upper end of said tube for applying a pulsating pneumatic pressure to the surface of the liquid in said tube so that said surface rises and falls in said tube.
Directory of Open Access Journals (Sweden)
Qutaiba A. Tawfic
2011-01-01
Full Text Available Mammals have lungs to breathe air and they have no gills to breath liquids. When the surface tension at the air-liquid interface of the lung increases, as in acute lung injury, scientists started to think about filling the lung with fluid instead of air to reduce the surface tension and facilitate ventilation. Liquid ventilation (LV is a technique of mechanical ventilation in which the lungs are insufflated with an oxygenated perfluorochemical liquid rather than an oxygen-containing gas mixture. The use of perfluorochemicals, rather than nitrogen, as the inert carrier of oxygen and carbon dioxide offers a number of theoretical advantages for the treatment of acute lung injury. In addition, there are non-respiratory applications with expanding potential including pulmonary drug delivery and radiographic imaging. The potential for multiple clinical applications for liquid-assisted ventilation will be clarified and optimized in future. Keywords: Liquid ventilation; perfluorochemicals; perfluorocarbon; respiratory distress; surfactant.
QUALITY AWARDS: AN IMAGE OF BUSINESS EXCELLENCE
Directory of Open Access Journals (Sweden)
Ilies Liviu
2015-07-01
Full Text Available Across the world, increasingly more governmental organizations and industrial are doing everything possible to promote quality and to survive, the basic principle remains customer satisfaction and even more than that, it speaks of the principle of customer delight. In this sense, quality has become the source of sustained competitive advantage that provides organizations the supremacy of the global markets characterized by competition which becoming more and more intensified. Juran, one of the highest quality gurus say that “just as the twentieth century was the century of productivity, the twenty-first century will be the quality century” which is a very relevant and comprehensive statement of the economic reality of the past and a profound forecast for future business of the twenty-first century. In this regard, in order to achieve this competitive advantage, quality must be managed and this is accomplished through Total Quality Management (TQM. Quality awards models are instruments of total quality management through which quality can be assessed and improved, thus, knowing the quality awards models is critical for findings the new ways to improve the quality and performance of the organizations. The present paper aims to illustrate the best practices on quality improvement in this respect we intend to present the general framework of the quality awards for business excellence. In this sense we present the most important international quality awards, namely: "Malcolm Baldrige National Quality Award", "European Quality Award" and “Romanian Quality Award J. M. Juran". For this purpose we used as main sources of analyzing the structure and the operation mode of these three important quality awards, Juran's work (which is probably the most important work in the field of quality and other relevant sources in total quality management which treats issues related to quality awards and also we used as sources of updated information the official
SARNET: Severe accident research network of excellence
International Nuclear Information System (INIS)
Albiol, Thierry; Haste, Tim; Dorsselaere, Jean-Pierre van
2007-01-01
51 organizations network in SARNET (Severe Accident Research NETwork of Excellence) their capacities of research in order to resolve the most important remaining uncertainties for enhancing, in regard of Severe Accidents (SA), the safety of existing and future Nuclear Power Plants (NPPs). This project, co-funded by the European Commission (EC), has been defined in order to optimise the use of the available means and to constitute sustainable research groups in the European Union. SARNET tackles the fragmentation that exists between the different R and D national programmes, in defining common research programmes and developing common computer tools and methodologies for safety assessment. SARNET comprises most of the actors involved in SA research in Europe (plus Canada). To reach these objectives, all the organizations networked in SARNET contribute to a so-called Joint Programme of Activities (JPA), which consists in: Implementing an advanced communication tool for accessing all project information, fostering exchange of information, and managing documents; Harmonizing and re-orienting the research programmes; Jointly analysing the experimental results provided by research programmes in order to elaborate a common understanding of relevant phenomena; Developing the ASTEC code (integral computer code used to predict the NPP behaviour during a postulated SA), which capitalizes in terms of physical models the knowledge produced within SARNET; Developing Scientific Databases, in which all the results of research programmes are stored in a common format (DATANET); Developing a common methodology for Probabilistic Safety Assessment (PSA) of NPPs; Developing courses and writing a text book on SA for students and researchers; Promoting personnel mobility between various European organizations. After the first period (2004-2008), co-funded by the EC, the network will progressively evolve toward self-sustainability. The bases for such an evolution, still under discussion
NOBLE and EXCEL: The debate for excellence in dealing with left main stenosis.
Kindi, Hamood Al; Samaan, Amir; Hosny, Hatem
2018-03-14
Left main coronary artery (LMCA) disease is associated with increased morbidity and mortality. Coronary artery bypass grafting surgery (CABG) has always been the standard revascularization strategy for this group of patients. However, with the recent developments in stents design and medical therapy over the past decade, several trials have been designed to evaluate the safety and efficacy of percutaneous coronary intervention (PCI) as an alternative to CABG surgery in patients with LMCA disease. Recently, the results of two major trials, EXCEL and NOBLE, comparing CABG versus PCI in this patient population have been released. In fact, the results of both trials might appear contradictory at first glance. While the EXCEL trial showed that PCI was non-inferior to CABG surgery, the NOBLE trial suggested that CABG surgery is a better option. In the following review, we will discuss some of the similarities and contrasts between these two trials and conclude with lessons to be learned to our daily practice.
DEFF Research Database (Denmark)
Malinova, Katya; Park, Andreas
2015-01-01
the breakdown of trading fees between liquidity demanders and suppliers matters. Posted quotes adjust after the change in fee composition, but the transaction costs for liquidity demanders remain unaffected once fees are taken into account. However, as posted bid-ask spreads decline, traders (particularly......Facing increased competition over the last decade, many stock exchanges changed their trading fees to maker-taker pricing, an incentive scheme that rewards liquidity suppliers and charges liquidity demanders. Using a change in trading fees on the Toronto Stock Exchange, we study whether and why...... retail) use aggressive orders more frequently, and adverse selection costs decrease....
Overcoming Microsoft Excel's Weaknesses for Crop Model Building and Simulations
Sung, Christopher Teh Boon
2011-01-01
Using spreadsheets such as Microsoft Excel for building crop models and running simulations can be beneficial. Excel is easy to use, powerful, and versatile, and it requires the least proficiency in computer programming compared to other programming platforms. Excel, however, has several weaknesses: it does not directly support loops for iterative…
Essentials of Excel, Excel VBA, SAS and Minitab for statistical and financial analyses
Lee, Cheng-Few; Chang, Jow-Ran; Tai, Tzu
2016-01-01
This introductory textbook for business statistics teaches statistical analysis and research methods via business case studies and financial data using Excel, MINITAB, and SAS. Every chapter in this textbook engages the reader with data of individual stock, stock indices, options, and futures. One studies and uses statistics to learn how to study, analyze, and understand a data set of particular interest. Some of the more popular statistical programs that have been developed to use statistical and computational methods to analyze data sets are SAS, SPSS, and MINITAB. Of those, we look at MINITAB and SAS in this textbook. One of the main reasons to use MINITAB is that it is the easiest to use among the popular statistical programs. We look at SAS because it is the leading statistical package used in industry. We also utilize the much less costly and ubiquitous Microsoft Excel to do statistical analysis, as the benefits of Excel have become widely recognized in the academic world and its analytical capabilities...
SARNET: Severe accident research network of excellence
International Nuclear Information System (INIS)
Albiol, T.; Van Dorsselaere, J. P.; Chaumont, B.; Haste, T.; Journeau, Ch.; Meyer, L.; Sehgal, Bal Raj; Schwinges, Bernd; Beraha, D.; Annunziato, A.; Zeyen, R.
2010-01-01
Fifty-one organisations network in SARNET (Severe Accident Research Network of Excellence) their research capacities in order to resolve the most important pending issues for enhancing, with regard to Severe Accidents (SA), the safety of existing and future Nuclear Power Plants (NPPs). This project. co-funded by the European Commission (EC) under the 6. Framework Programme, has been defined in order to optimise the use of the available means and to constitute sustainable research groups in the European Union. SARNET tackles the fragmentation that may exist between the different national R and D programmes, in defining common research programmes and developing common computer tools and methodologies for safety assessment. SARNET comprises most of the organisations involved in SA research in Europe, plus Canada. To reach these objectives, all the organisations networked in SARNET contributed to a joint Programme of Activities, which consisted of: Implementation of an advanced communication tool for accessing all project information, fostering exchange of information, and managing documents; Harmonization and re-orientation of the research programmes, and definition of new ones; Analysis of the experimental results provided by research programmes in order to elaborate a common understanding of relevant phenomena; Development of the ASTEC code (integral computer code used to predict the NPP behaviour during a postulated SA), which capitalizes in terms of physical models the knowledge produced within SARNET; Development of Scientific Databases in which all the results of research programmes are stored in a common format (DATANET); Development of a common methodology for Probabilistic Safety Assessment of NPPs; Development of short courses and writing a textbook on Severe Accidents for students and researchers; Promotion of personnel mobility amongst various European organisations. This paper presents the major achievements after four and a half years of operation of the
SWR 1000: Efficient design for operational excellence
International Nuclear Information System (INIS)
Brettschuh, W.
2008-01-01
The SWR 1000 boiling water reactor (BWR) offers all of the advantages associated with an advanced plant design, i.e. excellent safety performance and competitive power generation costs, in the medium capacity range (1000-1250 MW). The economic efficiency of this medium-sized plant in comparison with large-capacity designs is achieved by using very simple passive safety equipment, simplified plant operating systems, and a very simple plant configuration. Systems engineering is thus optimized, reducing dependence on electrical and instrumentation and control (I and C) systems. The fuel assemblies deployed in the SWR 1000 core are enlarged from a 10 x 10 to a 12 x 12 rod array. This cuts down the total number of fuel assemblies in the core and hence also the number of control rods and control rod drives, as well as in-core neutron flux monitors. The design owes its competitiveness to the fact that investment, maintenance and fuel cycle costs are all lower. In addition, refueling outages are shorter, thanks to the reduced scope for outage activities. For example, there are no bolted reactor internal joints, and the SWR 1000 has a permanently installed reactor vessel-to-drywell seal. Replacement of in-core detectors is carried out from below, and does not affect the critical path of the outage. Furthermore all in-service -inspections (ISIs) on the reactor pressure vessel (RPV) and its nozzles can be undertaken from the outside, so that no extended ISI outages are necessary. As in existing plants, forced coolant circulation is utilized, ensuring problem-free startup and enabling plant operators to adjust power rapidly in the high power range (70%-100%). This is achieved without moving the control rods, and allows both spectral-shift and stretch-out operation. The considerable gains provided by forced coolant circulation, in terms of operational flexibility and fuel utilization, mean that the investment and maintenance costs of the pumps are covered within just a few
Academic excellence workshops in chemistry and physics
Mills, Susan Rose
In the mid-1970's, Uri Treisman, at the University of California, Berkeley, developed an academic excellence workshop program that had important successes in increasing minority student achievement and persistence in calculus. The present dissertation research is an in-depth study of chemistry and physics workshops at the California State Polytechnic University, Pomona. Data for the first, longitudinal component of this study were obtained by tracking to Spring 1998 all workshop minority students, i.e., Latino, African American, and Native American workshop students, a random sample of non-workshop minority students, and a random sample of non-targeted students, i.e., Anglo and Asian students, enrolled in first-quarter General Chemistry or Physics during specific quarters of 1992 or 1993. Data for the second component were obtained by administering questionnaires, conducting interviews, and observing science students during Fall, 1996. Workshop participation was a significant predictor of first-quarter course grade for minority students in both chemistry and physics, while verbal and mathematics Scholastic Aptitude Test (SAT) scores were not significant predictors of beginning course grade for minority science students. The lack of predictive ability of the SAT and the importance of workshop participation in minority students' beginning science course performance are results with important implications for educators and students. In comparing pre-college achievement measures for workshop and non-targeted students, non-targeted students' mathematics SAT scores were significantly higher than chemistry and physics workshop students' scores. Nonetheless, workshop participation "leveled the field" as workshop and non-targeted students performed similarly in beginning science courses. Positive impacts of workshop participation on achievement, persistence, efficiency, social integration, and self-confidence support the continued and expanded funding of workshop programs
Excel 2013 all-in-one for dummies
Harvey, Greg
2013-01-01
The comprehensive reference, now completely up-to-date for Excel 2013! As the standard for spreadsheet applications, Excel is used worldwide - but it's not always user-friendly. However, in the hands of veteran bestselling author Greg Harvey, Excel gets a whole lot easier to understand! This handy all-in-one guide covers all the essentials, the new features, how to analyze data with Excel, and much more. The featured minibooks address Excel basics, worksheet design, formulas and functions, worksheet collaboration and review, charts and graphics, data management, data analysis, and
Matta, R.; Perotti, E.
2016-01-01
Can the risk of losses upon premature liquidation produce bank runs? We show how a unique run equilibrium driven by asset liquidity risk arises even under minimal fundamental risk. To study the role of illiquidity we introduce realistic norms on bank default, such that mandatory stay is triggered
DEFF Research Database (Denmark)
Pokutta, Sebastian; Schmaltz, Christian
2011-01-01
Large banking groups face the question of how to optimally allocate and generate liquidity: in a central liquidity hub or in many decentralized branches. We translate this question into a facility location problem under uncertainty. We show that volatility is the key driver behind (de......-)centralization. We provide an analytical solution for the 2-branch model and show that a liquidity center can be interpreted as an option on immediate liquidity. Therefore, its value can be interpreted as the price of information, i.e., the price of knowing the exact demand. Furthermore, we derive the threshold...... above which it is advantageous to open a liquidity center and show that it is a function of the volatility and the characteristic of the bank network. Finally, we discuss the n-branch model for real-world banking groups (10-60 branches) and show that it can be solved with high granularity (100 scenarios...
Modelización financiera con Excel
Directory of Open Access Journals (Sweden)
Lafuente Robledo, M.
1998-01-01
puramente didáctico facilita la comprensión y el estudio del alumno, el cual se tiene que centrar en los aspectos básicos de la asignatura, reduciéndose de forma muy importante la memorización de conceptos. · Permite determinar de manera rápida y exacta los distintos valores que sea necesario obtener y, consecuentemente, comparar entre distintas operaciones financieras planteadas al alumno de forma inmediata. · Operaciones con cálculos numéricos importantes, como la realización de cuadros de amortización de préstamos y empréstitos, también se pueden realizar con gran rapidez, y llevar a cabo un análisis de sensibilidad del mismo. · En general, permite resolver el problema hasta la solución final y extraer las conclusiones operativas, fase que en los cálculos manuales es muchas veces soslayada. Consecuentemente, facilita la detección de posibles inconsistencias y datos erróneos en los planteamientos y resultados. · La utilización de herramientas informáticas ayuda por otra parte a motivar a los alumnos como consecuencia del atractivo generalizado del soporte informático. No obstante, este aspecto no se puede generalizar a todos los alumnos, y además tiene un efecto que se diluye con el tiempo. A continuación, se desarrollan una serie de modelos de matemática financiera con hoja de cálculo con el objeto de ilustrar de forma clara y precisa como se pueden implementar dichos problemas financieros en Excel. Los tres primeros casos corresponden a la matemática financiera clásica y consideramos que deberían representar las aplicaciones informáticas mínimas de cualquier curso de esta disciplina en la Facultades y Escuelas Universitarias de Ciencias Empresariales.
Liu, Jiping
2015-01-01
The book drawing on the author's nearly half a century of energetic materials research experience intends to systematically review the global researches on liquid explosives. The book focuses on the study of the conception, explosion mechanism, properties and preparation of liquid explosives. It provides a combination of theoretical knowledge and practical examples in a reader-friendly style. The book is likely to be interest of university researchers and graduate students in the fields of energetic materials, blasting engineering and mining.
Teaching excellence in nursing education: a caring framework.
Sawatzky, Jo-Ann V; Enns, Carol L; Ashcroft, Terri J; Davis, Penny L; Harder, B Nicole
2009-01-01
Nursing education plays a central role in the ability to practice effectively. It follows that an optimally educated nursing workforce begets optimal patient care. A framework for excellence in nursing education could guide the development of novice educators, establish the basis for evaluating teaching excellence, and provide the impetus for research in this area. However, a review of the social sciences and nursing literature as well as a search for existing models for teaching excellence revealed an apparent dearth of evidence specific to excellence in nursing education. Therefore, we developed the Caring Framework for Excellence in Nursing Education. This framework evolved from a review of the generic constructs that exemplify teaching excellence: excellence in teaching practice, teaching scholarship, and teaching leadership. Nursing is grounded in the ethic of caring. Hence, caring establishes the foundation for this uniquely nursing framework. Because a teaching philosophy is intimately intertwined with one's nursing philosophy and the ethic of caring, it is also fundamental to the caring framework. Ideally, this framework will contribute to excellence in nursing education and as a consequence excellence in nursing practice and optimal patient care.
Excel 2003 all-in-one desk reference for dummies
Harvey, Greg
2013-01-01
When you think of number-crunching and spreadsheets, you think of Excel, right? After Word, it's the most popular program in the Microsoft Office suite. But if technical jargon isn't your first language, you may have found Excel just a teeny bit frustrating. It can be really hard to pick your way through the many features and make Excel do what you need for it to do. Once you know how, you can use Excel to Create fill-in-the-blank forms Prepare expense reports and invoices Manage all sorts of data Keep sales and inventory records Analyze financial data and create forecasts Present informati
Brewer, Maine Wastewater Treatment Plant Recognized for Excellence
The Brewer Water Pollution Control Facility was recently honored with a 2015 Regional Wastewater Treatment Plant Excellence Award by the US Environmental Protection Agency's New England regional office.
Head First Excel A learner's guide to spreadsheets
Milton, Michael
2010-01-01
Do you use Excel for simple lists, but get confused and frustrated when it comes to actually doing something useful with all that data? Stop tearing your hair out: Head First Excel helps you painlessly move from spreadsheet dabbler to savvy user. Whether you're completely new to Excel or an experienced user looking to make the program work better for you, this book will help you incorporate Excel into every aspect of your workflow, from a scratch pad for data-based brainstorming to exploratory analysis with PivotTables, optimizing outcomes with Goal Seek, and presenting your conclusions wit
PREFACE: Functionalized Liquid Liquid Interfaces
Girault, Hubert; Kornyshev, Alexei A.; Monroe, Charles W.; Urbakh, Michael
2007-09-01
Most natural processes take place at interfaces. For this reason, surface science has been a focal point of modern research. At solid-liquid interfaces one can induce various species to adsorb or react, and thus may study interactions between the substrate and adsorbates, kinetic processes, optical properties, etc. Liquid-liquid interfaces, formed by immiscible liquids such as water and oil, have a number of distinctive features. Both sides of the interface are amenable to detailed physical and chemical analysis. By chemical or electrochemical means, metal or semiconductor nanoparticles can be formed or localised at the interface. Surfactants can be used to tailor surface properties, and also to place organic molecular or supermolecular constructions at the boundary between the liquids. Electric fields can be used to drive ions from one fluid to another, or even change the shape of the interface itself. In many cases, both liquids are optically transparent, making functionalized liquid-liquid interfaces promising for various optical applications based on the transmission or reflection of light. An advantage common to most of these systems is self-assembly; because a liquid-liquid interface is not mechanically constrained like a solid-liquid interface, it can easily access its most stable state, even after it has been driven far from equilibrium. This special issue focuses on four modes of liquid-liquid interfacial functionalization: the controlled adsorption of molecules or nanoparticles, the formation of adlayers or films, electrowetting, and ion transfer or interface-localized reactions. Interfacial adsorption can be driven electrically, chemically, or mechanically. The liquid-liquid interface can be used to study how anisotropic particles orient at a surface under the influence of a field, how surfactants interact with other adsorbates, and how nanoparticles aggregate; the transparency of the interface also makes the chirality of organic adsorbates amenable to
Implementation and adaption of the Computer Code ECOSYS/EXCEL for Austria as OECOSYS/EXCEL
International Nuclear Information System (INIS)
Hick, H.; Suda, M.; Mueck, K.
1998-03-01
During 1989, under contract to the Austrian Chamber of the Federal Chancellor, department VII, the radioecological forecast model OECOSYS was implemented by the Austrian Research Centre Seibersdorf on a VAX computer using VAX Fortran. OECOSYS allows the prediction of the consequences after a large scale contamination event. During 1992, under contract to the Austrian Federal Ministry of Health, Sports and Consumer Protection, department III OECOSYS - in the version of 1989 - was implemented on PC's in Seibersdorf and the Ministry using OS/2 and Microsoft -Fortran. In March 1993, the Ministry ordered an update which had become necessary and the evaluation of two exercise scenarios. Since that time the prognosis model with its auxiliary program and communication facilities is kept on stand-by and yearly exercises are performed to maintain its readiness. The current report describes the implementation and adaption to Austrian conditions of the newly available EXCEL version of the German ECOSYS prognosis model as OECOSYS. (author)
Optimal Liquidation under Stochastic Liquidity
Becherer, Dirk; Bilarev, Todor; Frentrup, Peter
2016-01-01
We solve explicitly a two-dimensional singular control problem of finite fuel type for infinite time horizon. The problem stems from the optimal liquidation of an asset position in a financial market with multiplicative and transient price impact. Liquidity is stochastic in that the volume effect process, which determines the inter-temporal resilience of the market in spirit of Predoiu, Shaikhet and Shreve (2011), is taken to be stochastic, being driven by own random noise. The optimal contro...
Excel in the Accounting Curriculum: Perceptions from Accounting Professors
Ramachandran Rackliffe, Usha; Ragland, Linda
2016-01-01
Public accounting firms emphasize the importance of accounting graduates being proficient in Excel. Since many accounting graduates often aspire to work in public accounting, a question arises as to whether there should be an emphasis on Excel in accounting education. The purpose of this paper is to specifically look at this issue by examining…
Leadership Excellence in East and West: Reports from the Trenches
Hofstede, G.J.; Dooley, R.M.
2017-01-01
This article shows that leadership excellence is not uniformly perceived in one multinational. This study was done in a company active mainly in the USA, Malaysia and Singapore, half the management population (414 managers) joined in 39 focus sessions to define leadership excellence. This provided
Visual Processing in Generally Gifted and Mathematically Excelling Adolescents
Paz-Baruch, Nurit; Leikin, Roza; Leikin, Mark
2016-01-01
Little empirical data are available concerning the cognitive abilities of gifted individuals in general and especially those who excel in mathematics. We examined visual processing abilities distinguishing between general giftedness (G) and excellence in mathematics (EM). The research population consisted of 190 students from four groups of 10th-…
Excel Spreadsheets for Algebra: Improving Mental Modeling for Problem Solving
Engerman, Jason; Rusek, Matthew; Clariana, Roy
2014-01-01
This experiment investigates the effectiveness of Excel spreadsheets in a high school algebra class. Students in the experiment group convincingly outperformed the control group on a post lesson assessment. The student responses, teacher observations involving Excel spreadsheet revealed that it operated as a mindtool, which formed the users'…
Improving the Pedagogy of Capital Structure Theory: An Excel Application
Baltazar, Ramon; Maybee, Bryan; Santos, Michael R.
2012-01-01
This paper uses Excel to enhance the pedagogy of capital structure theory for corporate finance instructors and students. We provide a lesson plan that utilizes Excel spreadsheets and graphs to develop understanding of the theory. The theory is introduced in three scenarios that utilize Modigliani & Miller's Propositions and…
X-factor for innovation: identifying future excellent professionals
den Hertog, J.H.
2016-01-01
In this study we wanted to identify which type of individual is capable of achieving professional excellence. Our main question therefore read: which individual antecedents predict professional excellence? We chose to focus on personality traits and specifically on proactive personality - the
An integrated service excellence model for military test and ...
African Journals Online (AJOL)
The purpose of this article is to introduce an Integrated Service Excellence Model (ISEM) for empowering the leadership core of the capital-intensive military test and evaluation facilities to provide strategic military test and evaluation services and to continuously improve service excellence by ensuring that all activities ...
Automating Partial Period Bond Valuation with Excel's Day Counting Functions
Vicknair, David; Spruell, James
2009-01-01
An Excel model for calculating the actual price of bonds under a 30 day/month, 360 day/year day counting assumption by nesting the DAYS360 function within the PV function is developed. When programmed into an Excel spreadsheet, the model can accommodate annual and semiannual payment bonds sold on or between interest dates using six fundamental…
Empowering boards to become instruments of innovation and excellence
Coulson-Thomas, Colin
2016-01-01
Examines the roles of directors, boards and CEOs in relation to excellence, innovation, innovative business models, leadership and human capital and the digital economy, aspects of leadership and the new, collective and shared leadership required for creativity, innovation and entrepreneurship. Written to encourage discussion at the 2016 Dubai Global Convention and 26th World Congress for Business Excellence & Innovation.
Microsoft Excel Software Usage for Teaching Science and Engineering Curriculum
Singh, Gurmukh; Siddiqui, Khalid
2009-01-01
In this article, our main objective is to present the use of Microsoft Software Excel 2007/2003 for teaching college and university level curriculum in science and engineering. In particular, we discuss two interesting and fascinating examples of interactive applications of Microsoft Excel targeted for undergraduate students in: 1) computational…
Learning with animation as a framework for educational excellence
DEFF Research Database (Denmark)
Gjedde, Lisa
and the refinement of the expression. For some of the learners this type of learning environment, did present potentials for the experience of accomplishment, success and excellence, which they had rarely enjoyed in other types of learning environments. The notion of excellence will be reconsidered in relation...
BUSINESS EXCELLENCE AS A CRUCIAL COMPONENT FOR ORGANIZATION COMPETITIVENESS
Directory of Open Access Journals (Sweden)
Zeljko Pozega
2014-12-01
Full Text Available Background: Business excellence represents one of the most valuable management means of achieving competitive advantage of organizations. Modern and global market demands new organizational approaches for the long-term improvement at all organization levels. Objectives: This paper is concerned with the level of business excellence in Sibenik-Knin County and the level of knowledge about the EFQM model. Moreover, this paper is concerned with the level of knowledge of the top management concerning the business excellence and quality principles. Methods/Approach: For the purpose of this paper, the research was conducted among organizations in Sibenik-Knin County. Results: The results showed that the organizations in Sibenik-Knin County lack the initiatives for the systematic approach and implementation of business excellence model, but poses the knowledge about the basic concepts of business excellence. Conclusions: The research had showed that the organizations believe that the ISO certification is sufficient for strengthening competitive advantage and organization success.
Excellent Thinking and Its Position among EFL Learners
Directory of Open Access Journals (Sweden)
Gholamhossein Shahini
2018-03-01
Full Text Available The major goal of education, according to the educationalist Matthew Lipman (2003, is to culture students to become thoughtful by attaining excellent thinking power; i.e., critical, creative, and caring thinking ability. The purpose of this study was to examine the current status of excellent thinking among EFL students. Using accessible sampling, 41 EFL students at Shiraz University, Iran read two passages of various types and were asked to make a number of essay-type questions on each one. The results indicated that the majority of the questions were trivial reading comprehension ones with no sign of excellent thinking. The findings may imply that despite the significance of cultivating excellent thinking within students, no/scant attention is paid to this issue and EFL students have not still gained the necessary skills of excellent thinking.
Low-temperature behaviour of the Kob-Andersen binary mixture
International Nuclear Information System (INIS)
Ashwin S S; Sastry, Srikanth
2003-01-01
The dynamical behaviours of glass-forming liquids have been analysed extensively via computer simulations of model liquids, among which the Kob-Andersen binary Lennard-Jones mixture has been a widely studied system. Typically, studies of this model have been restricted to temperatures above the mode coupling temperature. Preliminary results concerning the dynamics of the Kob-Andersen binary mixture are presented at temperatures that extend below the mode coupling temperature, along with properties of the local energy minima sampled. These results show that a crossover in the dynamics occurs alongside changes in the properties of the inherent structures sampled. Furthermore, a crossover is observed from non-Arrhenius behaviour of the diffusivity above the mode coupling temperature to Arrhenius behaviour at lower temperatures
Chakraborty, Monojit; Chowdhury, Anamika; Bhusan, Richa; DasGupta, Sunando
2015-10-20
Droplet motion on a surface with chemical energy induced wettability gradient has been simulated using molecular dynamics (MD) simulation to highlight the underlying physics of molecular movement near the solid-liquid interface including the contact line friction. The simulations mimic experiments in a comprehensive manner wherein microsized droplets are propelled by the surface wettability gradient against forces opposed to motion. The liquid-wall Lennard-Jones interaction parameter and the substrate temperature are varied to explore their effects on the three-phase contact line friction coefficient. The contact line friction is observed to be a strong function of temperature at atomistic scales, confirming their experimentally observed inverse functionality. Additionally, the MD simulation results are successfully compared with those from an analytical model for self-propelled droplet motion on gradient surfaces.
Cumulative distribution functions associated with bubble-nucleation processes in cavitation
Watanabe, Hiroshi
2010-11-15
Bubble-nucleation processes of a Lennard-Jones liquid are studied by molecular dynamics simulations. Waiting time, which is the lifetime of a superheated liquid, is determined for several system sizes, and the apparent finite-size effect of the nucleation rate is observed. From the cumulative distribution function of the nucleation events, the bubble-nucleation process is found to be not a simple Poisson process but a Poisson process with an additional relaxation time. The parameters of the exponential distribution associated with the process are determined by taking the relaxation time into account, and the apparent finite-size effect is removed. These results imply that the use of the arithmetic mean of the waiting time until a bubble grows to the critical size leads to an incorrect estimation of the nucleation rate. © 2010 The American Physical Society.
Energy Technology Data Exchange (ETDEWEB)
Baer, M.R.; Hobbs, M.L.; McGee, B.C.
1998-11-03
Exponential-13,6 (EXP-13,6) potential pammeters for 750 gases composed of 48 elements were determined and assembled in a database, referred to as the JCZS database, for use with the Jacobs Cowperthwaite Zwisler equation of state (JCZ3-EOS)~l) The EXP- 13,6 force constants were obtained by using literature values of Lennard-Jones (LJ) potential functions, by using corresponding states (CS) theory, by matching pure liquid shock Hugoniot data, and by using molecular volume to determine the approach radii with the well depth estimated from high-pressure isen- tropes. The JCZS database was used to accurately predict detonation velocity, pressure, and temperature for 50 dif- 3 Accurate predictions were also ferent explosives with initial densities ranging from 0.25 glcm3 to 1.97 g/cm . obtained for pure liquid shock Hugoniots, static properties of nitrogen, and gas detonations at high initial pressures.
Application of Statistical Thermodynamics in Refrigeration
International Nuclear Information System (INIS)
Avsec, J.; Marcic, M.
1999-01-01
The paper presents the mathematical model for computing the thermodynamical properties in the liquid, gas and two-phase domain by means of statistical thermodynamics. The paper features all important components (translation, rotation, internal rotation, vibration, intermolecular potential energy and influence of electron and nuclei excitation). To calculate the thermodynamic properties of real gases, we have developed the cluster theory, which yields better results than the virial equation. In case of real liquids, the Johnson-Zollweg-Gubbins model based on the modified Benedict-Webb-Rubin (BWR) equation was applied. The Lennard-Jones intermolecular potential was used. The analytical results are compared with the thermodynamical data and models obtained from classical thermodynamics, and they show relatively good agreement. (author)
Liquidity risk and contagion for liquid funds
Darolles , Serge; Dudek , Jeremy; Le Fol , Gaëlle
2014-01-01
Fund managers face liquidity problems but they have to distinguish the market liquidity risk implied by their assets and the funding liquidity risk. This latter is due to both the liquidity mismatch between assets and liabilities and the redemption risk due to the possible outflows from clients. The main contribution of this paper is the analysis of contagion looking at common market liquidity problems to detect funding liquidity problems. Using the CDS Bond Spread basis as a liquidity indica...
Cebiroglu, Gökhan; Horst, Ulrich
2012-01-01
We cross-sectionally analyze the presence of aggregated hidden depth and trade volume in the S&P 500 and identify its key determinants. We find that the spread is the main predictor for a stock’s hidden dimension, both in terms of traded and posted liquidity. Our findings moreover suggest that large hidden orders are associated with larger transaction costs, higher price impact and increased volatility. In particular, as large hidden orders fail to attract (latent) liquidity to the market, hi...
Ionic-Liquid-Tethered Nanoparticles: Hybrid Electrolytes
Moganty, Surya S.
2010-10-22
A new class of solventless electrolytes was created by tethering ionic liquids to hard inorganic ZrO2 nanostructures (see picture; NIM=nanoscale ionic material). These hybrid fluids exhibit exceptional redox stability windows, excellent thermal stability, good lithium transference numbers, long-term interfacial stability in the presence of a lithium anode and, when doped with lithium salt, reasonable ionic conductivities.
A Tutorial on the Use of Excel 2010 and Excel for Mac 2011 for Conducting Delay-Discounting Analyses
Reed, Derek D.; Kaplan, Brent A.; Brewer, Adam T.
2012-01-01
In recent years, researchers and practitioners in the behavioral sciences have profited from a growing literature on delay discounting. The purpose of this article is to provide readers with a brief tutorial on how to use Microsoft Office Excel 2010 and Excel for Mac 2011 to analyze discounting data to yield parameters for both the hyperbolic…
Forgács, Attila; Balkay, László; Trón, Lajos; Raics, Péter
2014-12-01
Excel2Genie, a simple and user-friendly Microsoft Excel interface, has been developed to the Genie-2000 Spectroscopic Software of Canberra Industries. This Excel application can directly control Canberra Multichannel Analyzer (MCA), process the acquired data and visualize them. Combination of Genie-2000 with Excel2Genie results in remarkably increased flexibility and a possibility to carry out repetitive data acquisitions even with changing parameters and more sophisticated analysis. The developed software package comprises three worksheets: display parameters and results of data acquisition, data analysis and mathematical operations carried out on the measured gamma spectra. At the same time it also allows control of these processes. Excel2Genie is freely available to assist gamma spectrum measurements and data evaluation by the interested Canberra users. With access to the Visual Basic Application (VBA) source code of this application users are enabled to modify the developed interface according to their intentions. Copyright © 2014 Elsevier Ltd. All rights reserved.
Chasing Perfection and Catching Excellence in Graduate Medical Education.
Andolsek, Kathryn M
2015-09-01
The author reflects on the chapter titled "Preserving Excellence in Residency Training and Medical Care" in Dr. Kenneth Ludmerer's book Let Me Heal: The Opportunity to Preserve Excellence in American Medicine. Rather than assuming that the status quo represents excellence, however, the author asserts that we must make an informed judgment regarding the quality of graduate medical education (GME) by applying an evidence-based approach, carefully measuring performance against specific criteria. But what are the right criteria to judge excellence in GME? The author posits that the first criterion for excellence is the foundational concept identified by the Josiah Macy Jr. Foundation, that of accountability to the public. The author argues that for GME to be truly excellent it must produce a workforce "of sufficient size, specialty mix, and skill" needed to serve the public good. For GME to be truly excellent it must produce the right composition (reflecting the population it serves), use the right pedagogy, and be embedded within the right clinical learning environment. Implementation of competency-based education must be bolder and accelerated. The process of culling out service from education in GME must be more honest, not because all service cannot in some ways be educational but because it is simply too expensive to squander a single minute of time in training. Finally, the epidemic of burnout must be addressed urgently and innovatively.
BENCHMARKING WORKSHOPS AS A TOOL TO RAISE BUSINESS EXCELLENCE
Directory of Open Access Journals (Sweden)
Milos Jelic
2011-03-01
Full Text Available Annual competition for national award for business excellence appears to be a good opportunity for participating organizations to demonstrate their practices particularly those ones which enable them to excel. National quality award competition in Serbia (and Montenegro, namely "OSKAR KVALITETA" started in 1995 but was limited to competition cycle only. However, upon establishing Fund for Quality Culture and Excellence - FQCE in 2002, which took over OSKAR KVALITETA model, several changes took place. OSKAR KVALITETA turned to be annual competition in business excellence, but at the same time FQCE started to offer much wider portfolio of its services including levels of excellence programs, assessment and self-assessment training courses and benchmarking workshops. These benchmarking events have hosted by Award winners or other laureates in OSKAR KVALITETA competition who demonstrated excellence in regard of some particular criteria thus being in position to share their practice with other organizations. For six years experience in organizing benchmarking workshops FQCE scored 31 workshops covering major part of model issues. Increasing level of participation on the workshops and distinct positive trends of participants expressed satisfaction may serve as a reliable indicator that the workshops have been effective in actuating people to think and move in business excellence direction.
Sarkar, Suman; Paswan, Anil; Prakas, S
2014-01-01
Human have lungs to breathe air and they have no gills to breath liquids like fish. When the surface tension at the air-liquid interface of the lung increases as in acute lung injury, scientists started to think about filling the lung with fluid instead of air to reduce the surface tension and facilitate ventilation. Liquid ventilation (LV) is a technique of mechanical ventilation in which the lungs are insufflated with an oxygenated perfluorochemical liquid rather than an oxygen-containing gas mixture. The use of perfluorochemicals, rather than nitrogen as the inert carrier of oxygen and carbon dioxide offers a number of advantages for the treatment of acute lung injury. In addition, there are non-respiratory applications with expanding potential including pulmonary drug delivery and radiographic imaging. It is well-known that respiratory diseases are one of the most common causes of morbidity and mortality in intensive care unit. During the past few years several new modalities of treatment have been introduced. One of them and probably the most fascinating, is of LV. Partial LV, on which much of the existing research has concentrated, requires partial filling of lungs with perfluorocarbons (PFC's) and ventilation with gas tidal volumes using conventional mechanical ventilators. Various physico-chemical properties of PFC's make them the ideal media. It results in a dramatic improvement in lung compliance and oxygenation and decline in mean airway pressure and oxygen requirements. No long-term side-effect reported.
Khalil, Kareem
2012-12-01
Granulation, the process of formation of granules from a combination of base powders and binder liquids, has been a subject of research for almost 50 years, studied extensively for its vast applications, primarily to the pharmaceutical industry sector. The principal aim of granulation is to form granules comprised of the active pharmaceutical ingredients (API’s), which have more desirable handling and flowability properties than raw powders. It is also essential to ensure an even distribution of active ingredients within a tablet with the goal of achieving time‐controlled release of drugs. Due to the product‐specific nature of the industry, however, data is largely empirical [1]. For example, the raw powders used can vary in size by two orders of magnitude with narrow or broad size distributions. The physical properties of the binder liquids can also vary significantly depending on the powder properties and required granule size. Some significant progress has been made to better our understanding of the overall granulation process [1] and it is widely accepted that the initial nucleation / wetting stage, when the binder liquid first wets the powders, is key to the whole process. As such, many experimental studies have been conducted in attempt to elucidate the physics of this first stage [1], with two main mechanisms being observed – classified by Ivenson [1] as the “Traditional description” and the “Modern Approach”. See Figure 1 for a graphical definition of these two mechanisms. Recent studies have focused on the latter approach [1] and a new, exciting development in this field is the Liquid Marble. This interesting formation occurs when a liquid droplet interacts with a hydrophobic (or superhydrophobic) powder. The droplet can become encased in the powder, which essentially provides a protective “shell” or “jacket” for the liquid inside [2]. The liquid inside is then isolated from contact with other solids or liquids and has some
Promoting Excellence in Nursing Education (PENE): Pross evaluation model.
Pross, Elizabeth A
2010-08-01
The purpose of this article is to examine the Promoting Excellence in Nursing Education (PENE) Pross evaluation model. A conceptual evaluation model, such as the one described here, may be useful to nurse academicians in the ongoing evaluation of educational programs, especially those with goals of excellence. Frameworks for evaluating nursing programs are necessary because they offer a way to systematically assess the educational effectiveness of complex nursing programs. This article describes the conceptual framework and its tenets of excellence. Copyright 2009 Elsevier Ltd. All rights reserved.
Synthetic Organic Electrochemistry in Ionic Liquids: The Viscosity Question
Directory of Open Access Journals (Sweden)
Scott T. Handy
2011-07-01
Full Text Available Ionic liquids are obvious candidates for use in electrochemical applications due to their ionic character. Nevertheless, relatively little has been done to explore their application in electrosynthesis. We have studied the Shono oxidation of arylamines and carbamates using ionic liquids as recyclable solvents and have noted that the viscosity of the medium is a major problem, although with the addition of sufficient co-solvent, good results and excellent recovery and recycling of the ionic liquid can be achieved.
The effect of normal load on polytetrafluoroethylene tribology.
Barry, Peter R; Chiu, Patrick Y; Perry, Scott S; Sawyer, W Gregory; Phillpot, Simon R; Sinnott, Susan B
2009-04-08
The tribological behavior of oriented poly(tetrafluoroethylene) (PTFE) sliding surfaces is examined as a function of sliding direction and applied normal load in classical molecular dynamics (MD) simulations. The forces are calculated with the second-generation reactive empirical bond-order potential for short-range interactions, and with a Lennard-Jones potential for long-range interactions. The range of applied normal loads considered is 5-30 nN. The displacement of interfacial atoms from their initial positions during sliding is found to vary by a factor of seven, depending on the relative orientation of the sliding chains. However, within each sliding configuration the magnitude of the interfacial atomic displacements exhibits little dependence on load over the range considered. The predicted friction coefficients are also found to vary with chain orientation and are in excellent quantitative agreement with experimental measurements.
Molecular simulation of water removal from simple gases with zeolite NaA.
Csányi, Eva; Ható, Zoltán; Kristóf, Tamás
2012-06-01
Water vapor removal from some simple gases using zeolite NaA was studied by molecular simulation. The equilibrium adsorption properties of H(2)O, CO, H(2), CH(4) and their mixtures in dehydrated zeolite NaA were computed by grand canonical Monte Carlo simulations. The simulations employed Lennard-Jones + Coulomb type effective pair potential models, which are suitable for the reproduction of thermodynamic properties of pure substances. Based on the comparison of the simulation results with experimental data for single-component adsorption at different temperatures and pressures, a modified interaction potential model for the zeolite is proposed. In the adsorption simulations with mixtures presented here, zeolite exhibits extremely high selectivity of water to the investigated weakly polar/non-polar gases demonstrating the excellent dehydration ability of zeolite NaA in engineering applications.
Developing versus developed companies in Business Excellence initiatives
DEFF Research Database (Denmark)
Haffer, Rafal; Kristensen, Kai
2008-01-01
The paper reports the advance of Polish companies in Business Excellence initiatives. It indicates how these activities influence their performance. EFQM Excellence Model indicators are used as the evaluation criteria for the study. The performance variable is introduced to ensure the calculation...... of correlations between EFQM model indicators and performance results. The data are next estimated as a structural equation model by partial least squares using SmartPLS software (Ringle et al., 2005). That estimation is conducted on the model of the Danish Business Excellence Index methodology (Kristensen et al...... results from the Business Excellence Model as a proxy for actual financial results in Poland. Data and results from a similar study done in Denmark are also described; thus, a comparison between developing Polish companies and developed Danish ones is included. Poland and Denmark are used as cases of...
Equality and Excellence in Higher Education--Is It Possible?
Guri, Sarah
1986-01-01
The underlying philosophy of Everyman's University, Israel's open university, is to maintain educational excellence while providing equal educational opportunity to large segments of the population through free access and a flexible program of distance education. (MSE)
The Role of Libraries in the Search for Educational Excellence.
Breivik, Patricia Senn
1987-01-01
Discusses ways in which libraries can make a major contribution to the search for educational excellence and urges librarians to make a concerted effort to capture the attention of educational leaders. Four references are listed. (MES)
David Nolfi Receives NAHRS Award for Professional Excellence
Directory of Open Access Journals (Sweden)
Maureen Diana Sasso
2013-09-01
Full Text Available News AnnouncementDavid A. Nolfi, MLS, AHIP, Health Sciences Librarian & Library Assessment Coordinator at Duquesne University’s Gumberg Library, received the 2013 NAHRS Award for Professional Excellence at the One Health Conference in Boston, MA.
Excel-based scheduling for reallocation of nursing staff.
2016-10-19
Outi Annelli Tuominen and colleagues write in Nursing Management about the use of an Excel-based scheduling system for reallocation of nursing staff, which was trialled on ward managers and assistant ward managers.
Hotel shows health system keys to service excellence.
2003-08-01
Ritz-Carlton partnership part of broader program pursuing service excellence. Nearly 600 system leaders will participate in day-long seminars. GE, Harvard serve as strategic partners for ongoing educational efforts.
Elements of organizational culture leading to business excellence
Directory of Open Access Journals (Sweden)
Andrej Bertoncelj
2010-12-01
Full Text Available The main aim of this research was to define the development of a conceptual frame to understand the impact of organizational culture on business excellence in medium-sized and large Slovenian enterprises. In our research the focus was on the importance of the role of communication structure, interpersonal relationships, motivation, and stimulation as part of knowledge management among 825 managers working in medium-sized and large Slovenian enterprises. The aim was to find out if these elements lead or contribute to business excellence. To analyse our data we applied analysis of variance as research methods. Our proposed thesis was supported since significant differences in business excellence between enterprises, different in the above mentioned elements. We can conclude that an appropriate communication structure, interpersonal relationships, motivation, stimulation and values as part of organizational culture positively affect business excellence in enterprises
CERN visit of His Excellency Mr.Kinga Singye / Bhutan
Hoch, Michael
2016-01-01
CERN visit of His Excellency Mr Kinga Singye Ambassador Extraordinary and Plenipotentiary Permanent Representative of the Kingdom of Bhutan to the United Nations Office and other international organisations in Geneva
Center of Cancer Nanotechnology Excellence for Translational Diagnostics
The Center of Cancer Nanotechnology Excellence for Translational Diagnostics, which forms the third cycle CCNE Program at Stanford University, is a consortium that has three highly synchronized Projects and three Cores.
Centre of Excellence For Simulation Education and Innovation (CESEI).
Qayumi, A Karim
2010-01-01
Simulation is becoming an integral part of medical education. The American College of Surgeons (ACS) was the first organization to recognize the value of simulation-based learning, and to award accreditation for educational institutions that aim to provide simulation as part of the experiential learning opportunity. Centre of Excellence for Simulation Education and Innovation (CESEI) is a multidisciplinary and interprofessional educational facility that is based at the University of British Columbia (UBC) and Vancouver Costal Health Authority (VCH). Centre of Excellence for Simulation Education and Innovation's goal is to provide excellence in education, research, and healthcare delivery by providing a technologically advanced environment and learning opportunity using simulation for various groups of learners including undergraduate, postgraduate, nursing, and allied health professionals. This article is an attempt to describe the infrastructure, services, and uniqueness of the Centre of Excellence for Simulation Education and Innovation. Copyright 2010 Association of Program Directors in Surgery. Published by Elsevier Inc. All rights reserved.
Creating single-subject design graphs in Microsoft Excel 2007.
Dixon, Mark R; Jackson, James W; Small, Stacey L; Horner-King, Mollie J; Lik, Nicholas Mui Ker; Garcia, Yors; Rosales, Rocio
2009-01-01
Over 10 years have passed since the publication of Carr and Burkholder's (1998) technical article on how to construct single-subject graphs using Microsoft Excel. Over the course of the past decade, the Excel program has undergone a series of revisions that make the Carr and Burkholder paper somewhat difficult to follow with newer versions. The present article provides task analyses for constructing various types of commonly used single-subject design graphs in Microsoft Excel 2007. The task analyses were evaluated using a between-subjects design that compared the graphing skills of 22 behavior-analytic graduate students using Excel 2007 and either the Carr and Burkholder or newly developed task analyses. Results indicate that the new task analyses yielded more accurate and faster graph construction than the Carr and Burkholder instructions.
The computerized OMAHA system in microsoft office excel.
Lai, Xiaobin; Wong, Frances K Y; Zhang, Peiqiang; Leung, Carenx W Y; Lee, Lai H; Wong, Jessica S Y; Lo, Yim F; Ching, Shirley S Y
2014-01-01
The OMAHA System was adopted as the documentation system in an interventional study. To systematically record client care and facilitate data analysis, two Office Excel files were developed. The first Excel file (File A) was designed to record problems, care procedure, and outcomes for individual clients according to the OMAHA System. It was used by the intervention nurses in the study. The second Excel file (File B) was the summary of all clients that had been automatically extracted from File A. Data in File B can be analyzed directly in Excel or imported in PASW for further analysis. Both files have four parts to record basic information and the three parts of the OMAHA System. The computerized OMAHA System simplified the documentation procedure and facilitated the management and analysis of data.
Excel Computational Design Tool: Multifunctional Structure-Battery Materials
National Research Council Canada - National Science Library
Thomas, James
2003-01-01
.... SBDT is implemented in Excel spreadsheet form and is capable of analyzing composite designs with several cross-section geometries including circular-annular rectangular-annular, arbitrary-box, and multilayers...
The culture of excellence. Challenges and opportunities during changing times
Directory of Open Access Journals (Sweden)
Suciu Marta-Christina
2017-07-01
Full Text Available The main goal of the paper is to highlight the importance of supporting the promotion of the culture of excellence among people involved in a way or another in contemporary business. In order to support business excellence, the culture of excellence have to empower and engage all the people within an organization to think out of the box in a modern vision suitable to the challenging and changing times we are facing now. All over the world, in the most competitive countries, regions and sectors of activities there is a paradigmatic change of business strategies and policies oriented more and more towards performance and excellence. The paper highlights the importance of promoting the culture of excellence in the contemporary changing business environment. It suggests an important shift from a perspective that focuses on the so called ‘hero of excellence’ towards promoting the culture of excellence among the whole organization. Within modern business, in order to face challenges of the changing times and to explore their opportunities all the people from an organization are considered to manifest as ‘heroes of excellence’ by co-creating and co-working together within creative and innovative teams. They have to contribute and to participate actively to assure, preserve and develop the competitiveness and well being of the whole organization. The paper supports a holistic, cross disciplinary and integrated vision. It is structured into three parts including: a brief literature review based on an overview of the current state of the literature dedicated to the topic of culture of excellence (part 1; presentation of the main steps of the process of building a sustainable high performance organization (part 2; a brief presentation of examples of best practice and case studied identified internationally (part 3; conclusions that highlight the importance of culture of excellence in changing and challenging times.
Comparative Analysis Of Three Largest World Models Of Business Excellence
Directory of Open Access Journals (Sweden)
Jasminka Samardžija
2009-07-01
Full Text Available Business excellence has become the strongest means of achieving competitive advantage of companies while total management of quality has become the road that ensures support of excellent results recognized by many world companies. Despite many differences, we can conclude that models have many common elements. By the audit in 2005, the DP and MBNQA moved the focus from excellence of product, i.e service, onto the excellence of quality of the entire organization process. Thus, the quality got strategic dimension instead of technical one and the accent passed from the technical quality on the total excellence of all organization processes. The joint movement goes to the direction of good management and appreciation of systems thinking. The very structure of EFOM model criteria itself is adjusted to strategic dimension of quality and that is why the model underwent only short audits within the criteria themselves. Essentially, the model remained unchanged. In all models, the accent is on the satisfaction of buyers, employees and community. National rewards for quality have an important role in promotion and giving a prize to excellence in organization performances. Moreover, they raise quality standards of companies and the country profile as a whole. Considering the GDP per capita and the percentage of certification level of companies, Croatia has all the predispositions for introduction the EFQM model of business excellence with the basic aim of deficit decrease in foreign trade balance and strengthening of competitiveness as the necessary preliminary work for the entrance in the competitive market of the EU. Quality management was introduced in many organizations. The methods used at that time developed in the course of years, and what are to predict is the continuation of the evolution road model as well as the method of business excellence.
Atkins, K R
1959-01-01
Originally published in 1959 as part of the Cambridge Monographs on Physics series, this book addresses liquid helium from the dual perspectives of statistical mechanics and hydrodynamics. Atkins looks at both Helium Three and Helium Four, as well as the properties of a combination of the two isotopes. This book will be of value to anyone with an interest in the history of science and the study of one of the universe's most fundamental elements.
U.S. Environmental Protection Agency — Excel spreadsheets by species (4 letter code is abbreviation for genus and species used in study, year 2010 or 2011 is year data collected, SH indicates data for...
Coarse graining from variationally enhanced sampling applied to the Ginzburg-Landau model
Invernizzi, Michele; Valsson, Omar; Parrinello, Michele
2017-03-01
A powerful way to deal with a complex system is to build a coarse-grained model capable of catching its main physical features, while being computationally affordable. Inevitably, such coarse-grained models introduce a set of phenomenological parameters, which are often not easily deducible from the underlying atomistic system. We present a unique approach to the calculation of these parameters, based on the recently introduced variationally enhanced sampling method. It allows us to obtain the parameters from atomistic simulations, providing thus a direct connection between the microscopic and the mesoscopic scale. The coarse-grained model we consider is that of Ginzburg-Landau, valid around a second-order critical point. In particular, we use it to describe a Lennard-Jones fluid in the region close to the liquid-vapor critical point. The procedure is general and can be adapted to other coarse-grained models.
A variational approach to nucleation simulation.
Piaggi, Pablo M; Valsson, Omar; Parrinello, Michele
2016-12-22
We study by computer simulation the nucleation of a supersaturated Lennard-Jones vapor into the liquid phase. The large free energy barriers to transition make the time scale of this process impossible to study by ordinary molecular dynamics simulations. Therefore we use a recently developed enhanced sampling method [Valsson and Parrinello, Phys. Rev. Lett.113, 090601 (2014)] based on the variational determination of a bias potential. We differ from previous applications of this method in that the bias is constructed on the basis of the physical model provided by the classical theory of nucleation. We examine the technical problems associated with this approach. Our results are very satisfactory and will pave the way for calculating the nucleation rates in many systems.
International Nuclear Information System (INIS)
Forgács, Attila; Balkay, László; Trón, Lajos; Raics, Péter
2014-01-01
Excel2Genie, a simple and user-friendly Microsoft Excel interface, has been developed to the Genie-2000 Spectroscopic Software of Canberra Industries. This Excel application can directly control Canberra Multichannel Analyzer (MCA), process the acquired data and visualize them. Combination of Genie-2000 with Excel2Genie results in remarkably increased flexibility and a possibility to carry out repetitive data acquisitions even with changing parameters and more sophisticated analysis. The developed software package comprises three worksheets: display parameters and results of data acquisition, data analysis and mathematical operations carried out on the measured gamma spectra. At the same time it also allows control of these processes. Excel2Genie is freely available to assist gamma spectrum measurements and data evaluation by the interested Canberra users. With access to the Visual Basic Application (VBA) source code of this application users are enabled to modify the developed interface according to their intentions. - Highlights: • User-friendly Microsoft Excel interface to the Genie-2000 Spectroscopic software. • Data acquisitions with changing parameters and sophisticated data analysis. • Three worksheets: data acquisition, data analysis and mathematical operations on spectra. • The source code is freely available
Assessing excellence in translational cancer research: a consensus based framework.
Rajan, Abinaya; Caldas, Carlos; van Luenen, Henri; Saghatchian, Mahasti; van Harten, Wim H
2013-10-29
It takes several years on average to translate basic research findings into clinical research and eventually deliver patient benefits. An expert-based excellence assessment can help improve this process by: identifying high performing Comprehensive Cancer Centres; best practices in translational cancer research; improving the quality and efficiency of the translational cancer research process. This can help build networks of excellent Centres by aiding focused partnerships. In this paper we report on a consensus building exercise that was undertaken to construct an excellence assessment framework for translational cancer research in Europe. We used mixed methods to reach consensus: a systematic review of existing translational research models critically appraised for suitability in performance assessment of Cancer Centres; a survey among European stakeholders (researchers, clinicians, patient representatives and managers) to score a list of potential excellence criteria, a focus group with selected representatives of survey participants to review and rescore the excellence criteria; an expert group meeting to refine the list; an open validation round with stakeholders and a critical review of the emerging framework by an independent body: a committee formed by the European Academy of Cancer Sciences. The resulting excellence assessment framework has 18 criteria categorized in 6 themes. Each criterion has a number of questions/sub-criteria. Stakeholders favoured using qualitative excellence criteria to evaluate the translational research "process" rather than quantitative criteria or judging only the outputs. Examples of criteria include checking if the Centre has mechanisms that can be rated as excellent for: involvement of basic researchers and clinicians in translational research (quality of supervision and incentives provided to clinicians to do a PhD in translational research) and well designed clinical trials based on ground-breaking concepts (innovative
Predictors of excellent early outcome after total hip arthroplasty
Directory of Open Access Journals (Sweden)
Smith George H
2012-03-01
Full Text Available Abstract Background Not all patients gain the same degree of improvement from total hip replacement and the reasons for this are not clear. Many investigators have assessed predictors of general outcome after hip surgery. This study is unique in its quest for the predictors of the best possible early outcome. Methods We prospectively collected data on 1318 total hip replacements. Prior to surgery patient characteristics, demographics and co-morbidities were documented. Hip function and general health was assessed using the Harris Hip score (HHS and the Short-Form 36 respectively. The HHS was repeated at three years. We took a maximal HHS of 100 to represent an excellent outcome (102 patients. Multiple logistic regression analysis was used to identify independent predictors of excellent outcome. Results The two strongest predictive factors in achieving an excellent result were young age and a high pre-operative HHS (p = 0.001. Conclusions It was the young and those less disabled from their arthritis that excelled at three years. When making a decision about the timing of hip arthroplasty surgery it is important to take into account the age and pre-operative function of the patient. Whether these patients continue to excel however will be the basis of future research.
INPO and the industry: a commitment to excellence
International Nuclear Information System (INIS)
Colvin, J.F.
1985-01-01
Utilities in the United States have undergone major changes in their attitudes and methods of operating nuclear stations in the 6 yr since the accident at Three Mile Island. These changes reflect a strong commitment by the US utility industry to excellence in nuclear plant operations. Fundamental in this commitment was the formation of the Institute of Nuclear Power Operations (INPO), an organization created by the industry in the United States to serve as a focus and catalyst for these changes. With membership in INPO, nuclear utilities make a commitment to strive for excellence in the construction and operation of their nuclear plants. INPO has programs to help utilities in their efforts to achieve excellence. The most visible are the INPO evaluation programs. By the end of 1985, INPO will have evaluated most operating plants at least four times. Construction project evaluations are also being conducted. Twenty-one construction evaluations will have been conducted by the end of the year. Through each of its programs, INPO seeks to promote excellence and to help those operating and building nuclear plants in their commitment to excellence
TOP PRIORITI QMS PRINCIPLES FOR ACHIEVING BUSINESS EXCELLENCE
Directory of Open Access Journals (Sweden)
Aleksandar Vujović
2010-06-01
Full Text Available The main target of this paper is to select top priority principles of QMS for achieving business excellence. This could be done from the standpoint of significant of principles. That means that. organization should make more attention to this principles in the way for making excellent results. This paper has been developed as a tendency of researchers in the Center for quality-Faculty of mechanical engineering in Podgorica to establish a model for improvement of business processes performances based on quality management system through comparison with top organizational performances characterized by criteria i.e. particularities of the business excellence model. Correlation of principles of the quality management system with QMS principles has been established to that effect. Weight coefficients have been also determined for each principle individually. Thereby key principles were identified, namely priorities in terms of achieving business excellence i.e. areas (principles were given priorities, that is to say principles that play the biggest part in achieving business excellence.
Designing organizational excellence model for cellulose industry of Iran
Directory of Open Access Journals (Sweden)
Seyed Abbas Kazemi
2012-01-01
Full Text Available Nowadays organizational excellence is regarded as the world’s most effective and progressive issue and many countries and organizations are attempting in the way of applying excellence. In this way, they attempt to improve such models and according to culture and sociopolitical conditions of each country, they attempt to design several models. The present research has been conducted with principal goal of designing organizational excellence model at cellulose industry of Iran. The study determines its components and aspects, priorities the aspects and components and analyzes relationship among different aspects of organizational excellence model at cellulose industry of Iran. The present research is an applied research with respect to goal and it is a descriptive-analytical method in terms of method. Statistical population of the present research covers all experts in the field of cellulose industry of Iran in which on this basis, the number of statistical sample was 207 people from managers to specialists. Results of research indicate that organizational excellence pattern of cellulose industry is a mixture of different aspects of technical, economic, inner environment, outer environment, motivation and behavioral processes.
Learning Microsoft Excel 2011 for Mac video training DVD
Vaccaro, Guy
2011-01-01
In this video tutorial for Microsoft Excel 2011 For Mac, expert author Guy Vaccaro teaches you to effectively utilize the features and functions of Excel through project based learning. You will complete various projects, and along they way learn to leverage the power of the most important features Excel 2011 has to offer the Mac user. Starting your training course with the creation of a spreadsheet to record and monitor sales data, you will learn the basics of what you can do with a spreadsheet. You will then move on to creating a Profit and Loss report, learning formulas along the way. Moving to score sheets for a sports day, you will discover conditional based formatting, lookups, and more. You then create a functional expense claim form, advancing your Excel expertise. Moving on to a sales contact management sheet, you will discover how you can manipulate text, and even create mail merges from Excel. Finally, you will utilize all your knowledge thus far to create a sales report, including charts, pivot ta...
Bronson Methodist Hospital: journey to excellence in quality and safety.
Knapp, Cheryl
2006-10-01
Bronson Healthcare Group, a 343-bed not-for-profit health care system serving all of southwest Michigan and northern Indiana, has as its flagship Bronson Methodist Hospital, the recipient of the 2005 Malcolm Baldrige National Quality Award. The Baldrige criteria were used to formalize Bronson's approach to performance excellence. The strategic plan is condensed and communicated via a "Plan for Excellence" focused on three strategies: clinical excellence, customer and service excellence, and corporate effectiveness. Initiatives include clinical scene investigation (a system for reporting and investigating sentinel and atypical events), a strategy for educating staff in the Situation-Background-Assessment-Recommendations (SBAR) communication technique, and mandatory influenza immunization for health care staff (safety), patient health literacy needs and a health information center (patient centeredness); methods to reduce bloodstream and ventilator-acquired pneumonia infections (effectiveness); a physician portal for access to forms, test results, and patient information (efficiency); restaurant-style pagers for patients and families while waiting (timeliness); and community outreach (equity). Bronson's journey to excellence continues with more accountability for hand-off communication and teamwork, enhancing a non-punitive environment for patient safety reporting, and further incorporating patient and family involvement.
Ekechukwu, A.A.
1994-07-05
A dropping electrolyte electrode is described for use in electrochemical analysis of non-polar sample solutions, such as benzene or cyclohexane. The liquid electrode, preferably an aqueous salt solution immiscible in the sample solution, is introduced into the solution in dropwise fashion from a capillary. The electrolyte is introduced at a known rate, thus, the droplets each have the same volume and surface area. The electrode is used in making standard electrochemical measurements in order to determine properties of non-polar sample solutions. 2 figures.
International Nuclear Information System (INIS)
1976-01-01
The liquid diode is designed for a flowmeter chamber which has an inlet and an outlet duct, and a flow chamber with a cross-section which is greater than inlet. In the space between the inlet and outlet are two screens with a number of spheres, which may be of different sizes and weights. The screen on the inlet side is smaller than that at the outlet, so that the spheres are able to block the inlet under reverse flow conditions, but do not block the outlet. The system functions as a non-return valve. (G.C.)
Advancing diversity through inclusive excellence in nursing education.
Bleich, Michael R; MacWilliams, Brent R; Schmidt, Bonnie J
2015-01-01
Nurse leaders call for a more diverse nursing workforce, but too few address the concept of inclusion as a recruitment and retention strategy or as part of improving the academic learning milieu. This article addresses organizational considerations of diversity and inclusion as part of the agenda established by the Association of American Colleges and Universities for inclusive excellence, building on the idea that academic environments only become excellent when an inclusive climate is reached. Six organizational strategies to inclusion are presented from the authors' experiences, some structural and others behavioral: admissions processes, invisibility, absence of community, promotion and tenure, exclusion, and tokenism. A call for structural and behavioral adaptions within nursing education to advance an inclusive excellence agenda is presented. Copyright © 2015 Elsevier Inc. All rights reserved.
Promoting sustainable excellence through diversity in research careers
CERN. Geneva; Dr. Vinkenburg, Claartje; Guinot, Genevieve
2015-01-01
Excellence is a non-negotiable in science, a necessary condition for a successful careers as well as the funding of research projects. Scientific excellence is the sole criterion used by the European Research Council (ERC) to award frontier research grants. However, statistics show that there are still persistent inequalities between men and women scientists in ERC funding success as well as other career outcomes. Dr. Claartje Vinkenburg, of the VU University of Amsterdam, will illustrate two projects commissioned by the ERC Gender Balance Working Group to uncover and address this phenomenon. The first project [ERCAREER (Vinkenburg PI, 2012-2014)] is about unconventional careers and career breaks, and studies the gendered nature of career paths of ERC applicants. Findings show that “conventional careers” in science are inextricably tied to normative beliefs about the ideal academic, mobility, independence, and excellence. Allowing unconventional careers to address the issue results in ir...
Neutron activation analysis using Excel files and Canberra Genie-2000
International Nuclear Information System (INIS)
Landsberger, S.; Jackman, K.; Welch, L.
2005-01-01
A method for analyzing neutron activated sample data by using Microsoft Excel as the analysis engine has been developed. A simple technique for inputting data is based on report files generated by Canberra's Genie-2000 spectroscopy system but could be easily modified to support other vendors having report formats with consistent text placement. A batch program handles operating an automatic sample changer, acquiring the data, and analyzing the spectrum to create a report of the peak locations and net area. The entire report is then transferred to within an Excel spreadsheet as the source data for neutron activation analysis. Unique Excel templates have been designed, for example, to accommodate short-lived and long-lived isotopes. This process provides a largely integrated solution to NAA while providing the results in an industry standard spreadsheet format. This software is ideally suited for teaching and training purposes. (author)
From Funding Liquidity to Market Liquidity
DEFF Research Database (Denmark)
Dick-Nielsen, Jens; Lund, Jesper; Gyntelberg, Jacob
This paper shows empirically that funding liquidity drives market liquidity. As it becomes harder to secure term funding in the money markets, liquidity deteriorates in the Danish bond market. We show that the first principal component of bond market liquidity is driven by the market makers...... for other European government bonds using MTS data. The findings suggest that regulatory bond based liquidity buffers for banks will have limited effectiveness....
Liquid droplet radiator performance studies
Mattick, A. T.; Hertzberg, A.
By making use of droplets rather than solid surfaces to radiate waste heat in space, the liquid droplet radiator (LDR) achieves a radiating area/mass much larger than that of conventional radiators which use fins or heat pipes. The lightweight potential of the LDR is shown to be limited primarily by the radiative properties of the droplets. The requirement that the LDR heat transfer fluid have a very low vapor pressure limits the choice of fluids to relatively few—several liquid metals and Dow 705 silicone fluid are the only suitable candidates so far identified. An experimental determination of the emittance of submillimeter droplets of Dow 705 fluid indicates than an LDR using this fluid at temperatures of 275-335 K would be ⋍ 10 times lighter than the lightest solid surface radiators. Although several liquid metals appear to offer excellent performance in LDR applications at temperatures between 200 K and 975 K, experimental determination of liquid metal emissivities is needed for a conclusive assessment.
Microsoft Office Excel 2007 data analysis and business modeling
Winston, Wayne L
2007-01-01
Master the analysis and business modeling techniques that help you transform your data into bottom-line results. Award-winning business professor and corporate consultant Wayne Winston shares the best of his real-world experience in this practical guide-now updated for Excel 2007. Use Wayne's proven practices and hands-on exercises to help you work smarter, make better decisions, and gain the competitive edge. Solve real-world business problems with Excel 2007! Maximize profits-determine NPV, optimize your product mix, calculate ROICreate best, worst, and most-likely case scenarios for sal
External quality assurance agencies and excellence in higher education
Directory of Open Access Journals (Sweden)
Josep Grifoll
2016-07-01
Full Text Available The article presents briefly the complexity of the concept of “excellence” in higher education. Taking into account this reality, the fundamental question is how agencies can consider this complexity in building up criteria on excellence and the use of the concept “excellence” in their improvement strategies and accountability processes in the sector of higher education. Public-private nature of higher education and its growing internationalisation have significant impact on how excellence in education is described and promoted as a tool.
Proposing an Environmental Excellence Self-Assessment Model
DEFF Research Database (Denmark)
Meulengracht Jensen, Peter; Johansen, John; Wæhrens, Brian Vejrum
2013-01-01
that the EEA model can be used in global organizations to differentiate environmental efforts depending on the maturity stage of the individual sites. Furthermore, the model can be used to support the decision-making process regarding when organizations should embark on more complex environmental efforts......This paper presents an Environmental Excellence Self-Assessment (EEA) model based on the structure of the European Foundation of Quality Management Business Excellence Framework. Four theoretical scenarios for deploying the model are presented as well as managerial implications, suggesting...
Create dynamic charts in Microsoft Office Excel 2007 and beyond
Scheck, Reinhold
2009-01-01
Extend your Excel 2007 skills-and create more-powerful and compelling charts in less time. Guided by an Excel expert, you'll learn how to turn flat, static charts into dynamic solutions-where you can visualize and manipulate data countless ways with a simple mouse click. Get the hands-on practice and examples you need to produce your own, professional-quality results. No programming required! Maximize the impact of your ideas and data! Learn how your design decisions affect perception and comprehensionMatch the right chart type to your communication objectiveVisualize-then build-your solut
Excel Exercises for First-Year Engineering Students
Wagner, Geri
2006-01-01
Several Excel applications are presented which are part of the syllabus in the first semester of engineering studies at Haugesund College. The aim of the applications is for the students to acquire both computing skills and mathematical understanding at the same time. The applications cover numerical solution of equations, differentiation,…
Achievements of the EC network of excellence HySafe
Jordan, T.; Adams, P.; Azkarate, I.; Baraldi, D.; Barthelemy, H.; Bauwens, L.; Bengaouer, A.; Brennan, S.; Carcassi, M.; Dahoe, A.; Eisenreich, N.; Engebo, A.; Funnemark, E.; Gallego, E.; Gavrikov, A.; Haland, E.; Hansen, A.M.; Haugom, G.P.; Hawksworth, S.; Jedicke, O.; Kessler, A.; Kotchourko, A.; Kumar, S.; Langer, G.; Ledin, S.; Makarov, D.; Marangon, A.; Markert, F.; Middha, P.; Molkov, V.; Nilsen, S.; Papanikolaou, E.; Perrette, L.; Reinecke, E.-A.; Schmidtchen, U.; Serre-Combe, P.; Stöcklin, M.; Sully, A.; Teodorczyk, A.; Tigreat, D.; Venetsanos, A.; Verfondern, K.; Versloot, N.A.H.; Vetere, A.; Wilms, M.; Zaretskiy, N.
2009-01-01
In many areas European research has been largely fragmented. To support the required integration and to focus and coordinate related research efforts the European Commission created a new instrument, the Networks of Excellences (NoEs). The goal of the NoE HySafe has been to provide the basis to
Diversity and Excellence in Higher Education: Is There a Conflict?
Ghosh, Ratna
2012-01-01
In her teaching, research, and community activities in Canada, the author has repeatedly confronted questions regarding equality, diversity, and power. In this article, the author discusses diversity and equal opportunity to achieve excellence in education. Reflecting on these issues should help everyone to understand the complexities involved in…
Urban-Rural Excellence Gaps: Features, Factors, and Implications
Hernández-Torrano, Daniel
2018-01-01
The purpose of this study was to examine the presence of excellence gaps (i.e., differences between subgroups of students performing at the highest levels of achievement) in a sample of 563 students nominated as gifted by their teachers in urban, semi-urban, and rural settings in Spain. In general, the results suggested the existence of excellence…
Chinese College Students' Perceptions of Characteristics of Excellent Teachers
Liu, Shujie; Keeley, Jared; Buskist, William
2015-01-01
We "employed the Teacher Behavior Checklist" (TBC) to investigate Chinese college students' perceptions of excellent teachers' qualities and then compared the results to those from previously collected data from American and Japanese students. Chinese students tended to favor additional structure both in the classroom and in teachers'…
Creating an Excellence Oriented Post-merged Organisational ...
African Journals Online (AJOL)
This article specifically focuses on the importance of a structured approach to the implementation of employee engagement strategies in creating a post-merged organisational culture of excellent work performance. Theoretical insights from existing literature illustrate how a structured approach to the implementation of ...
Mining: An excellent option to invest in Colombia
International Nuclear Information System (INIS)
Diaz Orozco, Maria Claudia
2006-01-01
The paper mentions the geologic-miner potential that has Colombia, their geographical localization, modern mining legislation, a stable economy and in expansion and a regime of special of foreign investment and incentives that make of the mining an excellent investment option in the country
Program Excellence versus Program Growth: Must These Goals Conflict?
Goodstein, Lynne
2013-01-01
New England University (NEU) provides a case study of the risk that change might undermine an existing university asset in the context of growth in honors; it is a story about the efforts of faculty, students, and staff committed to evoking and sustaining excellence in one honors program to respond to the vision of a new president who placed…
Solving L-L Extraction Problems with Excel Spreadsheet
Teppaitoon, Wittaya
2016-01-01
This work aims to demonstrate the use of Excel spreadsheets for solving L-L extraction problems. The key to solving the problems successfully is to be able to determine a tie line on the ternary diagram where the calculation must be carried out. This enables the reader to analyze the extraction process starting with a simple operation, the…
Achieving Excellence in the Legal Profession in a Globalized World ...
African Journals Online (AJOL)
The increasing impacts of information technology and the internet have demystified knowledge and skills in all professions leaving the lawyer of today a person of business and ethics. The key argument in this paper is that ... knowledge and skill in that order. Keywords: Legal education, excellence, globalization, technology ...
The 2013 Aspen Prize for Community College Excellence
Perlstein, Linda
2013-01-01
For millions of Americans, community colleges provide an essential pathway to well-paying jobs and continuing higher education. The Aspen Prize for Community College Excellence honors those institutions that strive for and achieve exceptional levels of success for all students, while they are in college and after they graduate. Community colleges…
Defining Excellence: Lessons from the 2013 Aspen Prize Finalists
Aspen Institute, 2013
2013-01-01
In many respects, one couldn't find a group of 10 schools more diverse than the finalists for the 2013 Aspen Prize for Community College Excellence. One community college serves 1,500 students, another 56,000. There are institutions devoted primarily--even solely--to technical degrees, and ones devoted mainly to preparing students for further…
Year in Review: ASBO's Certificate of Excellence in Financial Reporting.
Gatti, Bernard F.
1995-01-01
Describes the Association of School Business Officials' (ASBO's) Certificate of Excellence for Financial Reporting review process for school district accounting and financial reporting. Describes the Self-Evaluation Worksheet revision, the panel of review members' guide, and highlights of program year 1994. Two figures are included. (LMI)
Development of an excel spreadsheet formean glandular dose in mammography
International Nuclear Information System (INIS)
Nagoshi, Kazuyo; Fujisaki, Tatsuya
2008-01-01
The purpose of this study was to develop an Excel spreadsheet to calculate mean glandular dose (D g ) in mammography using clinical exposure data. D g can be calculated as the product of incident air kerma (K a ) and D gN (i.e., D g =K a x D gN ). According to the method of Klein et al (Phys Med Biol 1997; 42: 651-671), K a was measured at the entrance surface with an ionization dosimeter. Normalized glandular dose (D gN ) coefficients, taking into account breast glandularity, were computed using Boone's method (Med Phys 2002; 29: 869-875). D gN coefficients can be calculated for any arbitrary X-ray spectrum. These calculation procedures were input into a Microsoft Excel spreadsheet. The resulting Excel spreadsheet is easy to use and is always applicable in the field of mammography. The exposure conditions concerning D g in clinical practice were also investigated in 22 women. Four exposure conditions (target/filter combination and tube voltage) were automatically selected in this study. This investigation found that average D g for each exposure was 1.9 mGy. Because it is recommended that quality control of radiation dose management in mammography is done using an American College of Radiology (ACR) phantom, information about patient dose is not obtained in many facilities. The present Excel spreadsheet was accordingly considered useful for optimization of exposure conditions and explanation of mammography to patients. (author)
Chemistry. Focus on Excellence, Volume 3, Number 2.
Penick, John E., Ed.; Krajcik, Joseph, Ed.
Eight examples of innovative and outstanding chemistry programs are described. These programs were selected using state criteria and at least four independent reviewers. While Project Synthesis offered a desired state, these examples of excellence provided views of what is already a reality. Included are the goals of an exemplary science program…
Operational excellence (six sigma) philosophy: Application to software quality assurance
Energy Technology Data Exchange (ETDEWEB)
Lackner, M.
1997-11-01
This report contains viewgraphs on operational excellence philosophy of six sigma applied to software quality assurance. This report outlines the following: goal of six sigma; six sigma tools; manufacturing vs administrative processes; Software quality assurance document inspections; map software quality assurance requirements document; failure mode effects analysis for requirements document; measuring the right response variables; and questions.
Using Excel's Matrix Operations to Facilitate Reciprocal Cost Allocations
Leese, Wallace R.; Kizirian, Tim
2009-01-01
The reciprocal method of service department cost allocation requires linear equations to be solved simultaneously. These computations are often so complex as to cause the abandonment of the reciprocal method in favor of the less sophisticated direct or step-down methods. Here is a short example demonstrating how Excel's sometimes unknown matrix…
Developing Competitive Excellence in the Talented Female Athlete.
Wildenhaus, Kevin J.
1995-01-01
This article reviews the historical development of female participation in sports, then identifies the unique issues associated with women's struggles for athletic acceptance and competitive excellence. Topics discussed include talent recognition and development, sex roles and socialization, physiology and maturation, coaching the female athlete,…
Making a World of Difference: Collaboration. Excellence for Intercultural Teams
Schneider, Luise; Romberg, Claudia
2011-01-01
Cultural awareness training that emphasizes communication delivers only a partial solution to the challenges that intercultural work teams face. Improving collaboration requires a strong foundation of performance management before a work team can determine how they will cooperate to perform to excellence. Against the backdrop of the authors'…
Assessing excellence in translational cancer research: a consensus based framework
Rajan, A.; Caldas, C.; van Luenen, H.; Saghatchian, M.; van Harten, Willem H.
2013-01-01
Background: It takes several years on average to translate basic research findings into clinical research and eventually deliver patient benefits. An expert-based excellence assessment can help improve this process by: identifying high performing Comprehensive Cancer Centres; best practices in
Rural Math Excel Partnership (RMEP) Project Final Performance Report
Harmon, Hobart; Tate, Veronica; Stevens, Jennifer; Wilborn, Sandy; Adams, Sue
2018-01-01
The goal of the Rural Math Excel Partnership (RMEP) project, a development project funded by the U.S. Department of Education Investing in Innovation (i3) grant program, was to develop a model of shared responsibility among families, teachers, and communities in rural areas as collective support for student success in and preparation for advanced…
Cultural Leadership: The Culture of Excellence in Education.
Cunningham, William G.; Gresso, Donn W.
Changing the system of rules, roles, and relationships that determine how the components of school redesign are addressed is the challenge that confronts administrators who seek to create a culture of excellence in schools. This book examines the role of effective leadership in achieving significant educational improvement, arguing that culture,…
Reducing Excellence Gaps: A Research-Based Model
Plucker, Jonathan A.; Peters, Scott J.; Schmalensee, Stephanie
2017-01-01
As the awareness of the existence and negative effects of excellence gaps has grown among educators and policy makers, so too has a desire for research-supported interventions to reduce these gaps. A recent review of research related to promoting equitable outcomes for all gifted students identified six specific strategies for reducing excellence…
Finding Aristotle's Golden Mean: Social Justice and Academic Excellence
Rivera, John
2005-01-01
Over 2,000 years ago, Aristotle wrote a treatise on ethics in which he proposed that there were both intellectual and moral virtues to be developed in the human being. Virtue ("aristeia") was roughly equivalent to the English word "excellence" and the unifying virtue that was both a moral and an intellectual virtue was…
Illustrating the Central Limit Theorem through Microsoft Excel Simulations
Moen, David H.; Powell, John E.
2005-01-01
Using Microsoft Excel, several interactive, computerized learning modules are developed to demonstrate the Central Limit Theorem. These modules are used in the classroom to enhance the comprehension of this theorem. The Central Limit Theorem is a very important theorem in statistics, and yet because it is not intuitively obvious, statistics…
WASP (Write a Scientific Paper) using Excel - 10: Contingency tables.
Grech, Victor
2018-06-01
Contingency tables may be required to perform chi-test analyses. This provides pointers as to how to do this in Microsoft Excel and explains how to set up methods to calculate confidence intervals for proportions, including proportions with zero numerators. Copyright © 2018 Elsevier B.V. All rights reserved.
WASP (Write a Scientific Paper) using Excel - 11: Test characteristics.
Grech, Victor
2018-07-01
The calculation of various test characteristics may be required as part of a data analysis exercise. This paper explains how to set up these calculations in Microsoft Excel in order to obtain sensitivity, specificity, positive and negative predictive values, diagnostic accuracy and prevalence. Copyright © 2018 Elsevier B.V. All rights reserved.
Maintaining excellence in teaching of human anatomy: University of ...
African Journals Online (AJOL)
Measures to address these challenges have resulted in wide disparities in curriculum design teaching methods, number and composition of instructors. Inspite of the challenges, the Department of Human Anatomy of the University of Nairobi (UON) maintained excellence of teaching for over 40yrs. This article describes the ...
Interaction potentials and their effect on crystal nucleation and symmetry
International Nuclear Information System (INIS)
Hsu, C.S.; Rahman, A.
1979-01-01
Molecular dynamics technique has been used to study the effect of the interaction potential on crystal nucleation and the symmetry of the nucleated phase. Four systems, namely rubidium, Lennard-Jones, rubidium-truncated, and Lennard-Jones-truncated, have been studied each at reduced density 0.95. Two types of calculations were performed. Firstly, starting from a liquid state, each system was quenched rapidly to a reduced temperature of approx.0.1. The nucleation process for these systems was monitored by studying the time dependence of temperature and the pair correlation function, and the resulting crystalline structure analyzed using among other properties the Voronoi polyhedra. Only in the case of rubidium was a b.c.c. structure nucleated. In the other three cases we obtained a f.c.c. ordering. Secondly, we have studied the effect of changing the interaction potential in a system which has already achieved an ordered state under the action of some other potential. After establishing a b.c.c. structure in a rubidium system, the change in the symmetry of the system was studied when the pair potential was modified to one of the other three forms. The results from both types of calculations are consistent: the rubidium potential leads to a b.c.c. structure while the other three potentials give an f.c.c. structure. Metastable disordered structures were not obtained in any of the calculations. However, the time elapse between the moment when the system is quick-quenched and the moment when nucleation occurs appears to depend upon the potential of interaction
Milchev, Andrey; Egorov, Sergei A; Binder, Kurt
2017-03-01
Semiflexible polymers under good solvent conditions interacting with attractive planar surfaces are investigated by Molecular Dynamics (MD) simulations and classical Density Functional Theory (DFT). A bead-spring type potential complemented by a bending potential is used, allowing variation of chain stiffness from completely flexible coils to rod-like polymers whose persistence length by far exceeds their contour length. Solvent is only implicitly included, monomer-monomer interactions being purely repulsive, while two types of attractive wall-monomer interactions are considered: (i) a strongly attractive Mie-type potential, appropriate for a strictly structureless wall, and (ii) a corrugated wall formed by Lennard-Jones particles arranged on a square lattice. It is found that in dilute solutions the former case leads to the formation of a strongly adsorbed surface layer, and the profile of density and orientational order in the z-direction perpendicular to the wall is predicted by DFT in nice agreement with MD. While for very low bulk densities a Kosterlitz-Thouless type transition from the isotropic phase to a phase with power-law decay of nematic correlations is suggested to occur in the strongly adsorbed layer, for larger densities a smectic-C phase in the surface layer is detected. No "capillary nematization" effect at higher bulk densities is found in this system, unlike systems with repulsive walls. This finding is attributed to the reduction of the bulk density (in the center of the slit pore) due to polymer adsorption on the attractive wall, for a system studied in the canonical ensemble. Consequently in a system with two attractive walls nematic order in the slit pore can occur only at a higher density than for a bulk system.