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Other Physics

Series

2010

Articles 1 - 8 of 8

Full-Text Articles in Physics

Pulsed Laser Deposition Of Graphite Counter Electrodes For Dye-Sensitized Solar Cells, Krishna P. Acharya, Himal Khatri, Sylvain Marsillac, Bruno Ullrich, Pavel Anzenbacher, Mikhail Zamkov Nov 2010

Pulsed Laser Deposition Of Graphite Counter Electrodes For Dye-Sensitized Solar Cells, Krishna P. Acharya, Himal Khatri, Sylvain Marsillac, Bruno Ullrich, Pavel Anzenbacher, Mikhail Zamkov

Electrical & Computer Engineering Faculty Publications

We report on pulsed laser deposition of graphite onto flexible plastic and conductive glass substrates for use as a counter electrode in dye-sensitized solar cells. The efficiency of as-prepared graphite electrodes was tested using CdS-sensitized solar cell architecture resulting in external quantum efficiency comparable to that of conventional platinum counter electrodes. This work highlights the possibility of using pulsed laser deposited graphite as a low-cost alternative to platinum, which could be fabricated both on flexible and rigid substrates.

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Upgrade To The Pierre Auger Cosmic Ray Observatory's Lidar System, Emily B. Petermann May 2010

Upgrade To The Pierre Auger Cosmic Ray Observatory's Lidar System, Emily B. Petermann

Department of Physics and Astronomy: Dissertations, Theses, and Student Research

The Pierre Auger Cosmic Ray Observatory currently operates four elastic lidar systems in order to characterize the atmospheric aerosol content above the observatory. The atmospheric information gained by the lidar system is then used in the calibration of the observatory’s four fluorescence detectors. Currently the four lidars in operation are unable to accurately determine the aerosol content below a distance of 1 km. A project is currently underway to upgrade the current lidar system by adding an additional detector to each of the existing lidar systems. The considered designs for this upgrade and the initial results from the upgrade prototype …

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Analysis Of An All-Optical Sbs Avalanche Detector, D. Walker, M. Steiner, Armen Gulian Feb 2010

Analysis Of An All-Optical Sbs Avalanche Detector, D. Walker, M. Steiner, Armen Gulian

Mathematics, Physics, and Computer Science Faculty Articles and Research

Seeding Brillouin scattering with a sufficiently efficient source of coherent phonons has the potential to produce energy-sensitive photon detectors. Based on this idea, we propose and analyze some possible designs for such a detector.

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Dynamical Theory Calculations Of Spin-Echo Resolved Grazing-Incidence Scattering From A Diffraction Grating, Rana Ashkar, P. Stonaha, A. L. Washington, V. R. Shah, M. R. Fitzsimmons, B. Maranville, C. F. Majkrzak, W. T. Lee, W. L. Schaich, Roger Pynn Jan 2010

Dynamical Theory Calculations Of Spin-Echo Resolved Grazing-Incidence Scattering From A Diffraction Grating, Rana Ashkar, P. Stonaha, A. L. Washington, V. R. Shah, M. R. Fitzsimmons, B. Maranville, C. F. Majkrzak, W. T. Lee, W. L. Schaich, Roger Pynn

Nebraska Center for Materials and Nanoscience: Faculty Publications

Neutrons scattered or reflected from a diffraction grating are subject to a periodic potential analogous to the potential experienced by electrons within a crystal. Hence, the wavefunction of the neutrons can be expanded in terms of Bloch waves and a dynamical theory can be applied to interpret the scattering phenomenon. In this paper, a dynamical theory is used to calculate the results of neutron spin-echo resolved grazing-incidence scattering (SERGIS) from a silicon diffraction grating with a rectangular profile. The calculations are compared with SERGIS measurements made on the same grating at two neutron sources: a pulsed source and a continuous …

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A Hybrid Particle-Continuum Method For Hydrodynamics Of Complex Fluids, Alejandro Garcia, A. Donev, J. B. Bell, B. Alder Jan 2010

A Hybrid Particle-Continuum Method For Hydrodynamics Of Complex Fluids, Alejandro Garcia, A. Donev, J. B. Bell, B. Alder

Faculty Publications

A previously developed hybrid particle-continuum method [J. B. Bell, A. Garcia, and S. A. Williams, Multiscale Model. Simul., 6 (2008), pp. 1256–1280] is generalized to dense fluids and two- and three-dimensional flows. The scheme couples an explicit fluctuating compressible Navier–Stokes solver with the isotropic direct simulation Monte Carlo (DSMC) particle method [A. Donev, A. L. Garcia, and B. J. Alder, J. Stat. Mech. Theory Exp., 2009 (2009), article P11008]. To achieve bidirectional dynamic coupling between the particle (microscale) and continuum (macroscale) regions, the continuum solver provides state-based boundary conditions to the particle subdomain, while the particle solver provides flux-based boundary …

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Computational Fluctuating Fluid Dynamics, Alejandro Garcia, J. B. Bell, S. Williams Jan 2010

Computational Fluctuating Fluid Dynamics, Alejandro Garcia, J. B. Bell, S. Williams

Faculty Publications

This paper describes the extension of a recently developed numerical solver for the Landau-Lifshitz Navier-Stokes (LLNS) equations to binary mixtures in three dimensions. The LLNS equations incorporate thermal fluctuations into macroscopic hydrodynamics by using white-noise fluxes. These stochastic PDEs are more complicated in three dimensions due to the tensorial form of the correlations for the stochastic fluxes and in mixtures due to couplings of energy and concentration fluxes (e.g., Soret effect). We present various numerical tests of systems in and out of equilibrium, including time-dependent systems, and demonstrate good agreement with theoretical results and molecular simulation

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On The Accuracy Of Explicit Finite-Volume Schemes For Fluctuating Hydrodynamics, Aleksandar Donev, Eric Vanden-Eijnden, Alejandro Garcia, John B. Bell Jan 2010

On The Accuracy Of Explicit Finite-Volume Schemes For Fluctuating Hydrodynamics, Aleksandar Donev, Eric Vanden-Eijnden, Alejandro Garcia, John B. Bell

Faculty Publications

This paper describes the development and analysis of finite-volume methods for the Landau–Lifshitz Navier–Stokes (LLNS) equations and related stochastic partial differential equations in fluid dynamics. The LLNS equations incorporate thermal fluctuations into macroscopic hydrodynamics by the addition of white noise fluxes whose magnitudes are set by a fluctuation-dissipation relation. Originally derived for equilibrium fluctuations, the LLNS equations have also been shown to be accurate for nonequilibrium systems. Previous studies of numerical methods for the LLNS equations focused primarily on measuring variances and correlations computed at equilibrium and for selected nonequilibrium flows. In this paper, we introduce a more systematic approach …

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Super-Resolution Using Adaptive Wiener Filters, Russell C. Hardie Jan 2010

Super-Resolution Using Adaptive Wiener Filters, Russell C. Hardie

Electrical and Computer Engineering Faculty Publications

The spatial sampling rate of an imaging system is determined by the spacing of the detectors in the focal plane array (FPA). The spatial frequencies present in the image on the focal plane are band-limited by the optics. This is due to diffraction through a finite aperture. To guarantee that there will be no aliasing during image acquisiton, the Nyquist criterion dictates that the sampling rate must be greater than twice the cut-off frequency of the optics. However, optical designs involve a number of trade-offs and typical imaging systems are designed with some level of aliasing. We will refer to …

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