Study on Self-maintenance of Clear-air Turbulence

2021 ◽  
pp. 15-19
Author(s):  
Krzysztof E. Haman
Keyword(s):  
Air Turbulence

scholarly journals In-Process Diameter Measurement Technique for Micro-Optical Fiber with Standing Wave Illumination

2021 ◽  
Author(s):  
Masaki Michihata ◽  
Zhao Zheng ◽  
Daiki Funaiwa ◽  
Sojiro Murakami ◽  
Shotaro Kadoya ◽  
...  
Keyword(s):  
Optical Fiber ◽  
Standing Wave ◽  
Dynamic Range ◽  
Scattered Light ◽  
High Dynamic Range ◽  
Measurement Range ◽  
Diameter Distribution ◽  
Process Measurement ◽  
Air Turbulence ◽  
Tapered Optical Fiber

AbstractIn this paper, we propose an in-process measurement method of the diameter of micro-optical fiber such as a tapered optical fiber. The proposed technique is based on analyzing optically scattered light generated by standing wave illumination. The proposed method is significant in that it requires an only limited measurement range and does not require a high dynamic range sensor. These properties are suitable for in-process measurement. This experiment verified that the proposed method could measure a fiber diameter as stable as ± 0.01 μm under an air turbulence environment. As a result of comparing the measured diameter distribution with those by scanning electron microscopy, it was confirmed that the proposed method has a measurement accuracy better than several hundred nanometers.

HODOGRAPH ANALYSIS AS APPLIED TO THE OCCURRENCE OF CLEAR-AIR TURBULENCE

1959 ◽  
Vol 16 (5) ◽  
pp. 588-592 ◽  
Author(s):  
Werner Schwerdtfeger ◽  
Uwe Radok
Keyword(s):  
Air Turbulence

Study of Biofilm and Fluidization of Bioparticles in a Three-Phase Liquid-Fluidized-Bed Reactor

1991 ◽  
Vol 23 (7-9) ◽  
pp. 1347-1354 ◽  
Author(s):  
F. Trinet ◽  
R. Heim ◽  
D. Amar ◽  
H. T. Chang ◽  
B. E. Rittmann
Keyword(s):  
Fluidized Bed ◽  
Liquid Velocity ◽  
Substrate Surface ◽  
Biofilm Reactor ◽  
Strongly Correlated ◽  
Polysaccharide Content ◽  
High Particle ◽  
Air Turbulence ◽  
Three Phase ◽  
Phase Liquid

A three-phase, liquid-fluidized-bed biofilm reactor was operated over wide ranges of liquid velocity, air velocity, medium concentration, and substrate surface loading. The biofilm characteristics (total colonization, polysaccharide content, density, and thickness) and the specific detachment coefficient (bs) were determined by a combination of experimental measurements and a hydrodynamic model. The results demonstrated that dense and thin biofilms were induced by the physical condition of high particle-to-particle contacts and high liquid turbulence. The biofilm's polysaccharide content was increased by increased air turbulence and a low substrate availability. The specific detachment coefficient, bs, was strongly correlated to the concentration of the medium (negatively) and the polysaccharide content (positively). Overall, the bs can be controlled significantly by the gas and liquid velocities; increasing either velocity tends to increase bs.

scholarly journals Impact of pitch angle fluctuations on airborne lidar forward sensing along the flight direction

2017 ◽  
Vol 10 (10) ◽  
pp. 3851-3864 ◽  
Author(s):  
Alexander Sergeevich Gurvich ◽  
Victor Alexeevich Kulikov
Keyword(s):  
Pitch Angle ◽  
Beam Steering ◽  
Airborne Lidar ◽  
Civil Aviation ◽  
Aerosol Layer ◽  
Flight Direction ◽  
Air Turbulence ◽  
Shear Turbulence ◽  
Geometrical Factors ◽  
Vertical Scales

Abstract. Airborne lidar forward sensing along the flight direction can serve for notification of clear air turbulence (CAT) and help to prevent injuries or fatal air accidents. The validation of this concept was presented in the framework of the DELICAT (DEmonstration of LIdar-based CAT detection) project. However, the strong variations in signal level, which were observed during the DELICAT measurements but not explained, sometimes indicated the need of a better understanding the observational errors due to geometrical factors. In this paper, we discuss possible error sources pertinent to this technique, related to fluctuations of the flight parameters, which may lead to strong signal variations caused by the random deviations of the sensing beam from the forward flight trajectory. We analyze the variations in backscattered lidar signal caused by fluctuations of the most important forward-sensing flight parameter, the pitch angle. The fluctuation values considered in the paper correspond to the error limits of the compensational gyro platform used in civil aviation. The part of the pitch angle fluctuations not compensated for by the beam-steering device in the presence of aerosol concentration variations can lead to noticeable signal variations that can be mistakenly attributed to wind shear, turbulence, or fast evolution of the aerosol layer. We formulate the criteria that allow the recognition of signal variations caused by pitch angle fluctuations. Influence of these fluctuations is shown to be stronger for aerosol variations on smaller vertical scales. An example of DELICAT observations indicating a noticeable pitch angle fluctuation impact is presented.

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