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Mathematics & Statistics

Modeling & simulation research

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Displaying 301 - 325 of 489

The effect of systematic errors on the hybridization of optical critical dimension measurements

June 21, 2015

Author(s)

Mark Alexander Henn, Richard M. Silver, Nien F. Zhang, Hui Zhou, Bryan M. Barnes

In hybrid metrology two or more measurements of the same measurand are combined to provide a more reliable result that ideally incorporates the individual strengths of each of the measurement methods. While these multiple measurements may come from

The Decoupled Potential Integral Equation for Time-Harmonic Electromagnetic Scattering

May 28, 2015

Author(s)

Felipe Vico, Leslie Greengard, Miguel Ferrando, Zydrunas Gimbutas

We present a new formulation for the problem of electromagnetic scattering from perfect electric conductors. While our representation for the electric and magnetic fields is based on the standard vector and scalar potentials A, φ in the Lorenz gauge, we

UWB Signal Processing: Projection, B-Splines, and Modified Gegenbauer Bases

May 25, 2015

Author(s)

Howard S. Cohl, Stephen D. Casey

Ultra-wide band (UWB) systems require either rapidly changing or very high sampling rates. Conventional analog-to-digital devices have limited dynamic range. We investigate UWB signal processing via a basis projection method and a basis system designed for

Area Coverage in a Fixed-Obstacle Environment using Mobile Sensor Networks

May 17, 2015

Author(s)

Kamran Sayrafian, Hamid Mahboubi, Amir Aghdam

In this chapter, efficient deployment strategies for mobile sensor networks are proposed to improve the coverage area in target fields containing obstacles. The developed algorithms iteratively calcu- late and update the position of the sensors in order to

Erratum to ``Bessel Functions'' (2014) by K.~B.~M.~Nambudiripad

May 15, 2015

Author(s)

Howard S. Cohl

The following errors and misprints have been detected in the monograph of Nambudiripad (2014) "Bessel Functions", Alpha Science International Ltd., Oxford, U.K.

Tokamak Plasma High Field Side Response to an n = 3 Magnetic Perturbation: A Comparison of 3D Equilibrium Solutions from Seven Different Codes

May 15, 2015

Author(s)

Allan Reiman, Antoine Cerfon, Geoffrey B. McFadden

In comparing equilibrium solutions for a DIII-D shot that is amenable to analysis by both stellarator and tokamak 3D equilibrium codes, a significant disagreement has been seen between solutions of the VMEC stellarator equilibrium code and solutions of

Design and modeling of an ultra-compact 2x2 nanomechanical plasmonic switch

May 4, 2015

Author(s)

Vladimir A. Aksyuk

A 2x2 Mach-Zehnder optical switch design with a footprint of 0.5 um x 2.5 um using nanomechanical gap plasmon phase modulators [1] is presented. The extremely small footprint and modest optical loss are enabled by the strong phase modulation of gap

A fast multipole method for the evaluation of elastostatic fields in a half-space with zero normal stress

April 30, 2015

Author(s)

Zydrunas Gimbutas, Leslie Greengard

In this paper, we present a fast multipole method (FMM) for the half-space Green's function in a homogeneous elastic half-space subject to zero normal stress, for which an explicit solution was given by Mindlin (1936). The image structure of this Green's

Fast Minimization of Region-based Active Contours using the Shape Hessian of the Energy

April 28, 2015

Author(s)

Gunay Dogan

We propose a novel shape optimization algorithm for region-based active contour models. Region-based active contours are preferred for many segmentation problems, because they incorporate more global information by aggregating cues or statistics over the

On the Stability of Rotating Drops

April 20, 2015

Author(s)

Asha K. Nurse, Sam R. Coriell, Geoffrey B. McFadden

We consider the equilibrium and stability of rotating axisymmetric fluid drops by appealing to a variational principle that characterizes the equilibria as stationary states of a functional containing surface energy and rotational energy contributions

Assessing Effects of Asymmetries, Dynamics, and Failures on a Cloud Simulator

March 29, 2015

Author(s)

Kevin L. Mills, James J. Filliben, Christopher E. Dabrowski

We characterize the effects of asymmetries, dynamics, and failures when introduced into a cloud computing simulator, which had previously been characterized under static, homogeneous configurations with various patterns of demand and supply. We aim to

A comparison of 3D shape retrieval methods based on a large-scale benchmark supporting multimodal queries

March 27, 2015

Author(s)

Afzal A. Godil

Large-scale 3D shape retrieval has become an important research direction in content-based 3D shape retrieval. To promote this research area, two Shape Retrieval Contest (SHREC) tracks on large scale comprehensive and sketch-based 3D model retrieval have

Multiscale Greens functions for modeling of nanomaterials: Bridging length and time scales

March 17, 2015

Author(s)

Vinod K. Tewary

Green's function gives the response of a system to a probe and is a powerful technique for solving a variety of problems in science and engineering. We describes a multiscale Green's function method for modeling nanomaterials at different length and time

Grain-scale thermoelastic stresses and spatiotemporal temperature gradients on airless bodies, implications for rock breakdown.

February 25, 2015

Author(s)

Stephen A. Langer

Thermomechanical processes such as fatigue and shock have been suggested to cause and contribute to rock breakdown on Earth, and on other planetary bodies, particularly airless bodies in the inner solar system. In this study, we modeled grain-scale

Computing the Time Evolution of the Apparent Viscoelastic/Viscoplastic Poisson's Ratio of Hydrating Cement Paste

February 15, 2015

Author(s)

Li xiodan, Zachary Grasley, Jeffrey W. Bullard, Edward Garboczi

A computational model has been developed that combines finite element methods with microstructure development simulations to quantitatively predict the viscoelastic/viscoplastic relaxation of cement paste due to intrinsic calcium silicate hydrate

Fourier and Gegenbauer expansions for a fundamental solution of Laplace's equation in hyperspherical geometry

February 14, 2015

Author(s)

Howard S. Cohl, Rebekah M. Palmer

For a fundamental solution of Laplace's equation on the R-radius d-dimensional hypersphere, we compute the azimuthal Fourier coefficients in closed form in two and three dimensions, and give an integral representation for the higher dimensions. We also

Randomized methods for rank-deficient linear systems

February 13, 2015

Author(s)

Josef Sifuentes, Zydrunas Gimbutas, Leslie Greengard

We present a simple, accurate method for solving consistent, rank-deficient linear systems, with or without additional rank-completing constraints. Such problems arise in a variety of applications, such as the computation of the eigenvectors of a matrix

Generalizations of generating functions for higher continuous hypergeometric orthogonal polynomials in the Askey scheme

February 9, 2015

Author(s)

Howard S. Cohl, Hans Volkmer, Michael Baeder

We use connection relations and series rearrangement to generalize generating functions for several higher continuous orthogonal polynomials in the Askey scheme, namely the Wilson, continuous dual Hahn, continuous Hahn, and Meixner-Pollaczek polynomials

Thermographic and FE Simulation of the DMLS Process at NIST

February 4, 2015

Author(s)

Brandon M. Lane, Li Ma, Shawn P. Moylan, M A. Donmez, Eric P. Whitenton, Daniel J. Falvey

A major effort of the Measurement Science for Additive Manufacturing Program at NIST is to provide high quality, well-defined temperature measurement of the DMLS process to support and validate multi-physics simulations. However, the dynamic, complex

A Decision Guidance Framework for Sustainability Performance Analysis of Manufacturing Processes

January 10, 2015

Author(s)

Duck B. Kim, Seungjun Shin, Guodong Shao, Alexander Brodsky

Life-Cycle Assessment (LCA) methods are widely used to assess the sustainability of manufacturing processes. Although it has several advantages such as systematic estimation and efficiency, it has significant limitations due to lack of functionality to

An efficient curve evolution algorithm for multiphase image segmentation

January 7, 2015

Author(s)

Gunay Dogan

We propose a novel iterative algorithm for segmentation of multiphase images by curve evolution. Specifically, we address a multiphase version of the Chan-Vese piecewise constant segmentation energy. Our algorithm is efficient: it is based on an explicit

Particle-based simulation of nanoscale systems and materials

January 1, 2015

Author(s)

Alexander Y. Smolyanitsky, Vinod K. Tewary

This book chapter is focused on the introduction of molecular dynamics (MD) and molecular statics (MS), as well as some of their uses for studying the thermomechanical and (indirectly) electronic properties at the nanoscale. We first introduce the general

A Semantic Framework for Modeling and Simulation of Cyber-physical Systems

December 30, 2014

Author(s)

Parastoo Delgoshaei, Mark Austin, Amanda Pertzborn

This paper describes a new semantic platform infrastructure for model-based systems engineering, requirements traceability, and system simulation and assessment of cyberphysical systems (CPSs). When fully developed this environment will support the

The Structure of Optimal and Near Optimal Target Sets in Consensus Models

December 19, 2014

Author(s)

Fern Y. Hunt

We consider the problem of identifying a subset of nodes in a network that will enable the fastest spread of information in a decentralized environment. In a model of communication based on a random walk on an undirected graph, the optimal set over all

DATA ANALYTICS USING SIMULATION FOR SMART MANUFACTURING

December 11, 2014

Author(s)

Guodong Shao, Sanjay Jain, Seungjun Shin

Manufacturing organizations are able to accumulate large amounts of plant floor production and environmental data due to advances in data collection, communications technology, and use of standards. The challenge has shifted from collecting a sufficient

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