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Pyrometry simulator (pyrosim) for diagnostic design

Dolan, Daniel H.

Signal estimates are crucial to the design of time-resolved pyrometry measurements. These estimates affect fundamental design decisions, including the optical relay (fiber versus open beam), spectral range (visible or infrared), and amplification needs (possibly at the expense of time resolution). The pyrosim program makes such estimates, allowing the collected power, photon flux, and measured signal to be determined in a broad range of pyrometry measurements. Geometrical collection limits can be applied; sample emissivity, transfer efficiency, and detector sensitivity may also be specified, either as constants or functions of wavelength.

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TYPE SAND Report YEAR 2011
DOIOSTI

Dynamic heat capacity of the east model and of a bead-spring polymer model

Mccoy, John D.; Brown, Jonathan R.; Adolf, Douglas B.

In this report we have presented a brief review of the glass transition and one means of characterizing glassy materials: linear and nonlinear thermodynamic oscillatory experiments to extract the dynamic heat capacity. We have applied these methods to the east model (a variation of the Ising model for glass forming systems) and a simple polymeric system via molecular dynamics simulation, and our results match what is seen in experiment. For the east model, since the dynamics are so simple, a mathematical model is developed that matches the simulated dynamics. For the polymeric system, since the system is a simulation, we can instantaneously 'quench' the system - removing all vibrational energy - to separate the vibrational dynamics from dynamics associated with particle rearrangements. This shows that the long-time glassy dynamics are due entirely to the particle rearrangements, i.e. basin jumping on the potential energy landscape. Finally, we present an extension of linear dynamic heat capacity to the nonlinear regime.

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TYPE SAND Report YEAR 2011
DOIOSTI

Standoff ultraviolet raman scattering detection of trace levels of explosives

Reichardt, Thomas A.; Bisson, Scott E.; Kulp, Thomas J.

Ultraviolet (UV) Raman scattering with a 244-nm laser is evaluated for standoff detection of explosive compounds. The measured Raman scattering albedo is incorporated into a performance model that focused on standoff detection of trace levels of explosives. This model shows that detection at {approx}100 m would likely require tens of seconds, discouraging application at such ranges, and prohibiting search-mode detection, while leaving open the possibility of short-range point-and-stare detection. UV Raman spectra are also acquired for a number of anticipated background surfaces: tile, concrete, aluminum, cloth, and two different car paints (black and silver). While these spectra contained features in the same spectral range as those for TNT, we do not observe any spectra similar to that of TNT.

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TYPE SAND Report YEAR 2011
DOIOSTI
Results 66801–66900 of 99,299
Results 66801–66900 of 99,299