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867 results on '"Roy, Sukesh"'

8. Analysis of Spatiotemporal Data

Author

Saha,, Anup, primary, Subramani, Harish, additional, Meyer, Terrence R., additional, Gunaratne, Gemunu, additional, Yi, Tongxun, additional, and Roy, Sukesh, additional

Published
2023
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23. High-speed intravascular photoacoustic imaging of lipid-laden atherosclerotic plaque enabled by a 2-kHz barium nitrite raman laser.

Author

Wang, Pu, Ma, Teng, Slipchenko, Mikhail N, Liang, Shanshan, Hui, Jie, Shung, K Kirk, Roy, Sukesh, Sturek, Michael, Zhou, Qifa, Chen, Zhongping, and Cheng, Ji-Xin

Subjects
Iliac Artery, Animals, Swine, Swine, Miniature, Lipids, Diagnostic Imaging, Lasers, Phantoms, Imaging, Plaque, Atherosclerotic, Photoacoustic Techniques, Miniature, Phantoms, Imaging, Plaque, Atherosclerotic, Bioengineering, Biochemistry and Cell Biology, Other Physical Sciences
Abstract

Lipid deposition inside the arterial wall is a key indicator of plaque vulnerability. An intravascular photoacoustic (IVPA) catheter is considered a promising device for quantifying the amount of lipid inside the arterial wall. Thus far, IVPA systems suffered from slow imaging speed (~50 s per frame) due to the lack of a suitable laser source for high-speed excitation of molecular overtone vibrations. Here, we report an improvement in IVPA imaging speed by two orders of magnitude, to 1.0 s per frame, enabled by a custom-built, 2-kHz master oscillator power amplifier (MOPA)-pumped, barium nitrite [Ba(NO3)2] Raman laser. This advancement narrows the gap in translating the IVPA technology to the clinical setting.

Published
2014

34. Megahertz-Rate Imaging of Hypersonic Boundary-Layer Instabilities in a Mach 10 Shock Tunnel

Author

Jiang, Naibo, primary, Hsu, Paul S., additional, Slipchenko, Mikhail, additional, Roy, Sukesh, additional, Lauriola, Daniel K., additional, Webb, Austin M., additional, Meyer, Terrence R., additional, Gragston, Mark, additional, Parker, Ron, additional, Portoni, Phillip, additional, McDermott, Conor, additional, Seitz, Kevin, additional, and Wadhams, Timothy P., additional

Published
2023
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42. 100-kHz Rate Rayleigh Imaging for Combustion and Flow Diagnostics

Author

Jiang, Naibo, Hsu, Paul S, Roy, Sukesh, Danehy, Paul M, and Zhang, Zhili

Subjects
Optics
Abstract

Two-dimensional (2D) Rayleigh scattering (RS) imaging at an ultrahigh repetition rate of 100 kHz is demonstrated in non-reacting and reacting flows employing a high-energy burst-mode laser system. Image sequences of flow mixture fraction were directly derived from high-speed RS images. Additionally, a 2D instantaneous flow velocity field at 100 kHz was obtained through optical-flow-based analysis of the RS images. The technique was also applied to study turbulent flames having a near-constant Rayleigh cross section. The demonstrated high-speed RS technique in conjunction with optical-flow-based analysis provides non-intrusive, simultaneous measurements of the flow mixing and velocity field, extending the measurement capability of the RS technique to high-speed non-reacting and reacting flows.

Published
2019

49. Mixture-Fraction Measurements with Femtosecond-Laser Electronic-Excitation Tagging

Author

Halls, Benjamin R, Jiang, Naibo, Gord, James R, Danehy, Paul M, and Roy, Sukesh

Subjects
Instrumentation And Photography, Optics
Abstract

Tracer-free mixture-fraction measurements were demonstrated in a jet using femtosecond-laser electronic-excitation tagging. Measurements were conducted across a turbulent jet at several downstream locations both in a pure-nitrogen jet exiting into an air-nitrogen mixture and in a jet containing an air-nitrogen mixture exiting into pure nitrogen. The signal was calibrated with known concentrations of oxygen in nitrogen. The spatial resolution of the measurement was approx.180 microns. The measurement uncertainty ranged from 5% to 15%, depending on the mixture fraction and location within the beam, under constant temperature and pressure conditions. The measurements agree with a mixture fraction of unity within the potential core of the jet and transition to the self-similar region.

Published
2017
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