366,425 research outputs found
Structural analysis of viscoelastic materials under thermal and pressure loading
Technique computes stresses resulting from axisymmetric transient thermal loading in circular solid-propellant grain section with circular ports. Propellant is assumed to be linear, thermal rheologically simple, viscoelastic material; material properties are represented by exponential series in time
Pair Interaction Potentials of Colloids by Extrapolation of Confocal Microscopy Measurements of Collective Structure
A method for measuring the pair interaction potential between colloidal
particles by extrapolation measurement of collective structure to infinite
dilution is presented and explored using simulation and experiment. The method
is particularly well suited to systems in which the colloid is fluorescent and
refractive index matched with the solvent. The method involves characterizing
the potential of mean force between colloidal particles in suspension by
measurement of the radial distribution function using 3D direct visualization.
The potentials of mean force are extrapolated to infinite dilution to yield an
estimate of the pair interaction potential, . We use Monte Carlo (MC)
simulation to test and establish our methodology as well as to explore the
effects of polydispersity on the accuracy. We use poly-12-hydroxystearic
acid-stabilized poly(methyl methacrylate) (PHSA-PMMA) particles dispersed in
the solvent dioctyl phthalate (DOP) to test the method and assess its accuracy
for three different repulsive systems for which the range has been manipulated
by addition of electrolyte.Comment: 35 pages, 14 figure
Valid conditions for the kramers-unsold continuum theory in a non-equilibrium plasma
Continuum intensity for electron-ion recombination in nonequilibrium plasm
Study of narrow-band dichroic plates with circular, rectangular, or Pyleguide apertures
The dichroic plate considered in this article is a metal plate perforated with arrays of apertures such that electromagnetic waves of certain frequencies pass through the plate and other frequencies are reflected. The shape of the apertures is an important contributor to the performance of the dichroic plate. An S/X dichroic plate, which passes X-band (8.4-8.45 GHz) and reflects S-band (2.0-2.32 GHz), is chosen for a case study. A comparison of the performance of dichroic plates of the same thickness and array pattern is presented for three different aperture shapes: circular, Pyleguide, and rectangular
Analysis of a thick dichroic plate with rectangular holes at arbitrary angles of incidence
A thick dichroic plate that is transparent to one frequency band while at the same time reflective to other frequencies is needed for high power transmission in the Deep Space Network. Software based on the method of moments was developed to design a thick dichroic plate with rectangular holes. A test dichroic plate was fabricated, and an experiment was performed to verify the computer code. Good agreement was found between theory and experiment
Finite element formulation for linear thermoviscoelastic materials
Report presents the finite difference equations in time and finite element matrix equations in space for general linear thermovisoelastic problems. The equations are derived for a general three-dimensional body but are applicable to one- and two-dimensional configurations with minor changes
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Visualizing latent domain knowledge
Knowledge discovery and data mining commonly rely on finding salient patterns of association from a vast amount of data. Traditional citation analysis of scientific literature draws insights from strong citation patterns. Latent domain knowledge, in contrast to the mainstream domain knowledge, often consists of highly relevant but relatively infrequently cited scientific works. Visualizing latent domain knowledge presents a significant challenge to knowledge discovery and quantitative studies of science. We build upon a citation-based knowledge visualization procedure and develop an approach that not only captures knowledge structures from prominent and highly cited works, but also traces latent domain knowledge through low-frequency citation chains. We apply this approach to two cases: (1) identifying cross-domain applications of Pathfinder networks (PFNETs) and (2) clarifying the current status of scientific inquiry of a possible link between Bovine spongiform encephalopathy (BSE), also known as mad cow disease, and a new variant Creutzfeldt-Jakob disease (vCJD), a type of brain disease in human
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