Optical Measurements of Hydrogen Mixing in Supersonic Airflows

1997 ◽  
pp. 71-79 ◽  
Author(s):  
F. Brellochs ◽  
M. Fertig ◽  
J. Algermissen ◽  
D. Brüggemann
Keyword(s):  
Optical Measurements

TEM characterization of proton-exchanged LiNbO3 optical waveguides

1986 ◽  
Vol 44 ◽  
pp. 480-481
Author(s):  
W. E. Lee
Keyword(s):  
Refractive Index ◽  
Benzoic Acid ◽  
Optical Waveguides ◽  
Total Internal Reflection ◽  
Index Of Refraction ◽  
Optical Measurements ◽  
Lithium Ions ◽  
Wide Channel ◽  
Tem Characterization

An optical waveguide consists of a several-micron wide channel with a slightly different index of refraction than the host substrate; light can be trapped in the channel by total internal reflection.Optical waveguides can be formed from single-crystal LiNbO3 using the proton exhange technique. In this technique, polished specimens are masked with polycrystal1ine chromium in such a way as to leave 3-13 μm wide channels. These are held in benzoic acid at 249°C for 5 minutes allowing protons to exchange for lithium ions within the channels causing an increase in the refractive index of the channel and creating the waveguide. Unfortunately, optical measurements often reveal a loss in waveguiding ability up to several weeks after exchange.

Magnetic and optical measurements and signatures of reconnection in the cusp and vicinity

2015 ◽  
Vol 185 (6) ◽  
pp. 655-663
Author(s):  
V.V. Safargaleev ◽  
T.I. Sergienko ◽  
A.V. Safargaleev ◽  
A.L. Kotikov
Keyword(s):  
Optical Measurements

Optical measurements for a superorbital expansion tube

1997 ◽  
Author(s):  
Margaret Wegener ◽  
Alexis Bishop ◽  
Amberyn Thomas ◽  
Margaret Wegener ◽  
Alexis Bishop ◽  
...  
Keyword(s):  
Optical Measurements ◽  
Expansion Tube

The Removal of Tunnel Vibration Induced Corruption in Aero-Optical Measurements

2014 ◽  
Author(s):  
Nicholas G. De Lucca ◽  
Stanislav Gordeyev ◽  
Adam E. Smith ◽  
Eric J. Jumper ◽  
Matthew Whiteley ◽  
...  
Keyword(s):  
Optical Measurements

scholarly journals Spectroscopic Techniques versus Pitot Tube for the Measurement of Flow Velocity in Narrow Ducts

Sensors ◽  
2020 ◽  
Vol 20 (24) ◽  
pp. 7349
Author(s):  
Francesco D’Amato ◽  
Silvia Viciani ◽  
Alessio Montori ◽  
Marco Barucci ◽  
Carmen Morreale ◽  
...  
Keyword(s):  
Flow Field ◽  
Flow Velocity ◽  
Pitot Tube ◽  
Optical Measurements ◽  
Trace Gas ◽  
Dual Function ◽  
Spectroscopic Techniques ◽  
Gas Composition ◽  
Flow Conditions ◽  
Theoretical Simulation

In order to assess the limits and applicability of Pitot tubes for the measurement of flow velocity in narrow ducts, e.g., biomass burning plants, an optical, dual function device was implemented. This sensor, based on spectroscopic techniques, targets a trace gas, injected inside the stack either in bursts, or continuously, so performing transit time or dilution measurements. A comparison of the two optical techniques with respect to Pitot readings was carried out in different flow conditions (speed, temperature, gas composition). The results of the two optical measurements are in agreement with each other and fit quite well the theoretical simulation of the flow field, while the results of the Pitot measurements show a remarkable dependence on position and inclination of the Pitot tube with respect to the duct axis. The implications for the metrology of small combustors’ emissions are outlined.

scholarly journals Characterization of swelling behavior of carbon nano-filler modified polydimethylsiloxane composites

2021 ◽  
pp. 009524432110061
Author(s):  
Bo Yang ◽  
Balakrishnan Nagarajan ◽  
Pierre Mertiny
Keyword(s):  
Digital Image Analysis ◽  
Swelling Behavior ◽  
Optical Measurements ◽  
Natural Phenomenon ◽  
Cross Linking ◽  
Dimensional Changes ◽  
Experimental Findings ◽  
Carbon Based

Polymers may absorb fluids from their surroundings via the natural phenomenon of swelling. Dimensional changes due to swelling can affect the function of polymer components, such as in the case of seals, microfluidic components and electromechanical sensors. An understanding of the swelling behavior of polymers and means for controlling it can improve the design of polymer components, for example, for the previously mentioned applications. Carbon-based fillers have risen in popularity to be used for the property enhancement of resulting polymer composites. The present investigation focuses on the effects of three carbon-based nano-fillers (graphene nano-platelets, carbon black, and graphene nano-scrolls) on the dimensional changes of polydimethylsiloxane composites due to swelling when immersed in certain organic solvents. For this study, a facile and expedient methodology comprised of optical measurements in conjunction with digital image analysis was developed as the primary experimental technique to quantify swelling dimensional changes of the prepared composites. Other experimental techniques assessed polymer cross-linking densities and elastic mechanical properties of the various materials. The study revealed that the addition of certain carbon-based nano-fillers increased the overall swelling of the composites. The extent of swelling further depended on the organic solvent in which the composites were immersed in. Experimental findings are contrasted with published models for swelling prediction, and the role of filler morphology on swelling behavior is discussed.

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