• Title/Summary/Keyword: Tapered Piston

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Infrared Scanning Near-Field Optical Microscopy (IR-SNOM) Below the Diffraction Limit

  • Sanghera, J.S.;Aggarwal, I.D.;Cricenti, A.;Generossi, R.;Luce, M.;Perfetti, P.;Margoritondo, G.;Tolk, N.;Piston, D.
    • Ceramist
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    • v.10 no.3
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    • pp.55-66
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    • 2007
  • Infrared Scanning Near-field Optical Microscopy (IR-SNOM) is an extremely powerful analytical instrument since it combines IR spectroscopy's high chemical specificity with SNOM's high spatial resolution. In order to do this in the infrared, specialty chalcogenide glass fibers were fabricated and their ends tapered to generate SNOM probes. The fiber tips were installed in a modified near field microscope and both inorganic and biological samples illuminated with the tunable output from a free-electron laser located at Vanderbilt University. Both topographical and IR spectral images were simultaneously recorded with a resolution of ${\sim}50\;nm$ and ${\sim}100\;nm$, respectively. Unique spectroscopic features were identified in all samples, with spectral images exhibiting resolutions of up to ${\lambda}/60$, or at least 30 times better than the diffraction limited lens-based microscopes. We believe that IR-SNOM can provide a very powerful insight into some of the most important bio-medical research topics.

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A Study on Analytical Approach for Performance Evaluation of Pyrotechnically Actuated Device (파이로작동기구 성능평가를 위한 해석모델 연구)

  • Choi, Joo-Ho;Sung, Hong-Gye;Kim, Jun-Sik
    • Proceedings of the Korean Society of Propulsion Engineers Conference
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    • 2012.05a
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    • pp.63-64
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    • 2012
  • A pyrotechnic actuated device (PAD) is a component that delivers high power in remote environments by combustion of a self-contained energy source. Historically, the design of these devices has been largely empirical and considered to be an art. In this study, an overview for developing an analytical model is introduced that efficiently evaluates performance of PAD. The model is integrated by three parts of different disciplines that are coupled in sequence with each other. First is the solid explosive burning to form product gas within an actuator and transport to an expansion chamber. Second is the insertion of initially tapered piston into a small hole by gas pressure in the chamber. Third is the shear cutting of the diaphragm from the piston to enable gas flow into the conduit. Some results of preliminary study for each of three parts are introduced in the presentation.

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