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Search Publications by: William L. George (Fed)

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Displaying 1 - 25 of 38

Visualization Ecology Applications for Measurement Science: A Visualization Gap Approach

June 13, 2022
Author(s)
Simon Su, William Sherman, Steven G. Satterfield, Terence J. Griffin, William L. George, Sandy Ressler, Shaw C. Feng, Judith E. Terrill
Advanced visualization research have remained insufficiently included in science and engineering workflows due to the highly specialized task-specific requirements and lack of suitable applications. Although the field of visualization is maturing and

Intermediate Scattering Functions of a Rigid Body Monoclonal Antibody Protein in Solution Studied by Dissipative Particle Dynamic Simulation

April 8, 2021
Author(s)
Yanqin Zhai, Nicos Martys, William L. George, Joseph E. Curtis, Jannatun Nayem, Y. Z, Yun Liu
In the past decade, there is increased research interest in studying internal motions of flexible proteins in solution using Neutron Spin Echo (NSE) as NSE can simultaneously probe the dynamics at the length and time scale comparable to protein domain

Pipe Flow of Sphere Suspensions having a Power-Law-Dependent Fluid Matrix

March 5, 2020
Author(s)
Nicos Martys, William L. George, Ryan P Murphy, Kathleen M Weigandt
Measurement and prediction of suspension flow properties in cylindrical geometries represents a significant challenge for both the experimentalist and modeller. In this paper, results of a computational study of suspension flow in a pipe geometry using a

Certification of SRM 2497: Standard Reference Concrete for Rheological Measurements

April 22, 2019
Author(s)
Nicos Martys, Max A. Peltz, William L. George, Blaza Toman, Edward J. Garboczi, Chiara Ferraris
Rotational rheometers are commonly used to determine the rheological properties of fluids such as viscosity and yield stress [Fer12]. Manufacturers generally recommend the use of a standard oil of known viscosity to verify that the instrument is operating

An Overset Mesh Framework for an Isentropic ALE Navier-Stokes HDG Formulation

January 6, 2019
Author(s)
Justin A. Kauffman, William L. George, Jonathan S. Pitt
Fluid-structure interaction simulations where solid bodies undergo large deformations require special handling of the mesh motion for Arbitrarily Lagrangian-Eulerian (ALE) formulations. Such formulations are necessary when body-fitted meshes with certain

Certification of SRM 2493:Standard Reference Mortar for Rheological Measurements

October 4, 2017
Author(s)
Alex Olivas, Chiara C. Ferraris, Nicos Martys, Edward Garboczi, Blaza Toman, William L. George
Rheological measurements are often performed using a rotational rheometer. In this type of rheometer, the tested fluid is sheared between two surfaces, one of which acts as the rotating surface [1]. Usually, the rotational velocity is imposed and the

Application Creation for an Immersive Virtual Measurement and Analysis Laboratory

December 21, 2016
Author(s)
Wesley N. Griffin, William L. George, Terence J. Griffin, John G. Hagedorn, Thomas M. Olano, Steven G. Satterfield, James S. Sims, Judith E. Terrill
Content creation for realtime interactive systems is a difficult problem. In game development, content creation pipelines are a major portion of the code base and content creation is a major portion of the budget. In research environments, the choice of

Rheological Measurement of Suspensions Without Slippage: Experimental and Model

December 13, 2016
Author(s)
Alex Olivas, Michelle A. Helsel, Nicos Martys, Chiara C. Ferraris, William L. George, Raissa Ferron
The conclusion of international studies was that the optimal approach to calibrate concrete rheometers would be to develop a non-Newtonian standard reference material (SRM) that contained inclusions similar in size to aggregates used commonly in concrete

Modeling of Suspension Flow in a Pipe Geometry and Rheometers

May 18, 2016
Author(s)
Nicos Martys, Chiara F. Ferraris, William L. George
Abstract Measurement and prediction of the flow of suspensions like cement based materials represents a significant challenge for both the experimentalist and modeler. In this paper, results of a computational study of suspension flow in a pipe and a

Calibration of rheometers for cementitious materials

May 16, 2016
Author(s)
Chiara F. Ferraris, Nicos Martys, William L. George, Edward J. Garboczi, Alex Olivas
The calibration of rheometers to determine the rheological properties of cement based materials ranging from cement paste to concrete cannot be done using standard oils as they are cost prohibitive and do not possess sufficient granularity to test slip

Universal scaling law for the flow of non-Newtonian colloidal suspension

October 1, 2014
Author(s)
Nicos Martys, William L. George, Maxime Liard, Pascal Hebraud, Didier Lootens
It has been observed that flow curves (viscosity vs shear-rate) of spherical non-colloidal particles suspended in a non-Newtonian fluid matrix can be rescaled so as to collapse onto the flow curve of the matrix fluid. This result is surprising given the

Development of Standard Reference Materials for Cement-Based Materials

January 6, 2014
Author(s)
Chiara F. Ferraris, Nicos Martys, William L. George
Rotational rheometers are routinely used for homogeneous materials, but their usage for characterization of a granular fluid like concrete is a relatively new phenomenon. As measurements with rheometers can involve flow in a complex geometry, it is

Development of Standard Reference Materials for Cement-Based Materials

May 13, 2013
Author(s)
Chiara F. Ferraris, Nicos Martys, William L. George
Rheometers are used to determine the rheological properties of materials ranging from mayonnaise to concrete. While rotational rheometers are routinely used for homogeneous materials such as mayonnaise, their usage for characterization of a granular fluid

Stress propagation in a colloidal suspension under shear

March 1, 2012
Author(s)
William L. George, Pascal Hebraud, Didier Lootens, Mouhamad Khalil, Nicos Martys
The stress propagation in a concentrated attractive colloidal suspension, under shear, is studied using mumerical simulations. A novel way of describing the intercolloidal stress field is proposed and its spatial correlations are studied. An inertia-like

Advancing the materials science of concrete with supercomputers

January 24, 2011
Author(s)
Jeffrey W. Bullard, Edward Garboczi, William L. George, Nicos Martys, Steven G. Satterfield, Judith E. Terrill
Supercomputers are renowned for being used on grand challenge problems like global weather patterns, nuclear device virtual testing, galaxy formation, unraveling molecular structure - and now concrete! Why do the mysteries of concrete form this kind of a

Contact and Stress Anisotropies in Start Up Flows of Collodial Suspensions

September 11, 2009
Author(s)
Nicos Martys, William L. George, Didier Lootens, Pascal Hebraud
Spatio-temporal correlations in start-up flows of attractive colloids are explored by numerical simulations. The suspension is first allowed to flocculate during a time tw, then the stress necessary to induce its flow is computed. Whereas at low volume

Extending Measurement Science to Interactive Visualization Environments

January 30, 2009
Author(s)
Judith E. Terrill, William L. George, Terence J. Griffin, John G. Hagedorn, John T. Kelso, Thomas M. Olano, Adele P. Peskin, Steven G. Satterfield, James S. Sims, Jeffrey W. Bullard, Joy P. Dunkers, Nicos Martys, Agnes A. O'Gallagher, Gillian Haemer
We describe a method for creating a visual laboratory to interactively measure and analyze scientific data. We move the normal activities that scientists perform to understand their data into the visualization environment. The visualization environment is

Spatial-Temporal Correlations at the Onset of Flow in Concentrated Suspensions

July 7, 2008
Author(s)
Nicos Martys, Didier Lootens, William L. George, Steven G. Satterfield, Pascal Hebraud
Spatial-temporal correlations in the startup-up flow of colloidal suspensions composed of attractive spherical particles under static and shear conditions are studied by computer simulation. The evolution of particle organization with time is followed as

Stress chains formation under shear of concentrated suspension

July 7, 2008
Author(s)
Didier Lootens, Nicos Martys, William L. George, Steven G. Satterfield, Pascal Hebraud
Results comparing experiments on a model system of mono-disperse silica-particles with the numerical simulation of highly concentrated suspension of spherical particles subject to a constant rate of strain are presented. Giant fluctuations of the shear

Accelerating Scientific Discovery through Computation and Visualization III. Tight-binding Wave Functions for Quantum Dots

June 2, 2008
Author(s)
James S. Sims, John G. Hagedorn, Steven G. Satterfield, Terence J. Griffin, William L. George, Howard Hung, John T. Kelso, Thomas M. Olano, Adele P. Peskin, Judith E. Terrill, Garnett W. Bryant, Jose G. Diaz
This is the third in a series of articles that describe, through examples, how the Scientific Applications and Visualization Group (SAVG) at NIST has utilized high performance parallel computing, visualization, and machine learning to accelerate scientific

Science at the Speed of Thought

February 1, 2005
Author(s)
J E. Devaney, Steven G. Satterfield, John T. Kelso, Adele Peskin, William L. George, John G. Hagedorn, Terence J. Griffin, Howard Hung, R D. Kriz

Parallel Programming with Interoperable MPI

February 1, 2004
Author(s)
William L. George, John G. Hagedorn, J E. Devaney
In this article we describe IMPI (Interoperable Message Passing Interface), a message passing protocol that allows you to easily run parallel programs across multiple clusters, SMPs (symmetric multiprocessors), parallel machines, personal computers, and