A New Approach to Nonuniform Sampling of Bounded Atmospheric Turbulence Spectra

2020 ◽  
Author(s):  
Jonas Krimmer ◽  
Christoph Fullner ◽  
Sebastian Randel
Keyword(s):  
Atmospheric Turbulence ◽  
Nonuniform Sampling ◽  
New Approach ◽  
Turbulence Spectra

4-aperture differential image motion monitor as a new approach for estimating atmospheric turbulence parameters

2019 ◽  
Vol 66 (7) ◽  
pp. 753-763 ◽  
Author(s):  
B. Dibaee ◽  
R. Shomali ◽  
J. Khalilzadeh ◽  
A. Jafari ◽  
M. Amniat-Talab
Keyword(s):  
Atmospheric Turbulence ◽  
Image Motion ◽  
New Approach ◽  
Turbulence Parameters

Rational New Approach to the Response of an Aircraft Encountering Atmospheric Turbulence

AIAA Journal ◽  
1980 ◽  
Vol 18 (2) ◽  
pp. 129-137 ◽  
Author(s):  
J.C.T. Wang ◽  
S. F. Shen
Keyword(s):  
Atmospheric Turbulence ◽  
New Approach

scholarly journals Energy Spectra of Atmospheric Turbulence for Calculating Cn2 Parameter. I. Maidanak and Suffa Observatories in Uzbekistan

Atmosphere ◽  
2021 ◽  
Vol 12 (12) ◽  
pp. 1614
Author(s):  
Artem Yu. Shikhovtsev ◽  
Pavel G. Kovadlo ◽  
Evgeniy A. Kopylov ◽  
Mansur A. Ibrahimov ◽  
Shuhrat A. Ehgamberdiev ◽  
...  
Keyword(s):  
Refractive Index ◽  
Atmospheric Turbulence ◽  
Baroclinic Instability ◽  
Structure Constant ◽  
Index Structure ◽  
Energy Spectra ◽  
Atmospheric Conditions ◽  
Astronomical Observations ◽  
Turbulence Spectra ◽  
Wide Range

Knowledge of the turbulence spectra is of interest for describing atmospheric conditions as applied to astronomical observations. This article discusses the deformations of the turbulence spectra with heights in a wide range of scales at the sites of the Maidanak and Suffa observatories. It is shown that the energy of baroclinic instability is high at the sites of these observatories and should be taken into account in the calculations of the refractive index structure constant Cn2.

scholarly journals Low-altitude Sensing of Urban Atmospheric Turbulence with UAV

2022 ◽  
Author(s):  
Alexander Shelekhov ◽  
Aleksey Afanasiev ◽  
Evgenia Shelekhova ◽  
Alexey Kobzev ◽  
Alexey Tel’minov ◽  
...  
Keyword(s):  
Atmospheric Turbulence ◽  
Urban Areas ◽  
Energy Production ◽  
Least Square ◽  
High Frequency Region ◽  
Inhomogeneous Surface ◽  
Turbulence Spectra ◽  
Least Square Fit ◽  
Weather Stations ◽  
Low Altitude

The capabilities of a quadcopter in the hover mode for low-altitude sensing of atmospheric turbulence with high spatial resolution in urban areas characterized by complex orography are investigated. The studies were carried out in different seasons (winter, spring, summer, and fall), and the quadcopter hovered in the immediate vicinity of ultrasonic weather stations. The DJI Phantom 4 Pro quadcopter and AMK-03 ultrasonic weather stations installed in different places of the studied territory were used in the experiment. The smoothing procedure was used to main regularities in the behavior of the longitudinal and lateral spectra of turbulence in the inertial and energy production ranges. The longitudinal and lateral turbulence scales were estimated by the least-square fit method with the von Karman model as a regression curve. It is shown that the turbulence spectra obtained with DJI Phantom 4 Pro and AMK-03 generally coincide with minor differences observed in the high-frequency region of the spectrum. In the inertial range, the behavior of the turbulence spectra shows that they obey the Kolmogorov-Obukhov “5/3” law. In the energy production range, the longitudinal and lateral turbulence scales and their ratio measured by DJI Phantom 4 Pro and AMK-03 agree to a good accuracy. Discrepancies in the data obtained with the quadcopter and the ultrasonic weather stations at the territory with complex orography are explained by the partial correlation of the wind velocity series at different measurement points and the influence of the inhomogeneous surface.

scholarly journals New Approach for Unambiguous High-Resolution Wide-Swath SAR Imaging

2014 ◽  
Vol 2014 ◽  
pp. 1-9
Author(s):  
Yueguan Lin ◽  
Yida Fan ◽  
Hai Jiang ◽  
Wei Wang
Keyword(s):  
High Resolution ◽  
Nonuniform Sampling ◽  
New Approach ◽  
Spatial Coverage ◽  
Sar Imaging ◽  
Small Antenna ◽  
Effective Phase ◽  
Imaging Algorithms ◽  
Azimuth Resolution ◽  
Wide Swath

The high-resolution wide-swath (HRWS) SAR system uses a small antenna for transmitting waveform and multiple antennas both in elevation and azimuth for receiving echoes. It has the potential to achieve wide spatial coverage and fine azimuth resolution, while it suffers from elevation pattern loss caused by the presence of topographic height and impaired azimuth resolution caused by nonuniform sampling. A new approach for HRWS SAR imaging based on compressed sensing (CS) is introduced. The data after range compression of multiple elevation apertures are used to estimate direction of arrival (DOA) of targets via CS, and the adaptive digital beamforming in elevation is achieved accordingly, which avoids the pattern loss of scan-on-receive (SCORE) algorithm when topographic height exists. The effective phase centers of the system are nonuniformly distributed when displaced phase center antenna (DPCA) technology is adopted, which causes Doppler ambiguities under traditional SAR imaging algorithms. Azimuth reconstruction based on CS can resolve this problem via precisely modeling the nonuniform sampling. Validation with simulations and experiment in an anechoic chamber are presented.

The O–C diagrams of minor planets − a new approach to modelling the rotation

1999 ◽  
Vol 173 ◽  
pp. 185-188
Author(s):  
Gy. Szabó ◽  
K. Sárneczky ◽  
L.L. Kiss
Keyword(s):  
Error Analysis ◽  
Time Dependence ◽  
Theoretical Work ◽  
Minor Planet ◽  
Minor Planets ◽  
New Approach ◽  
Preliminary Results ◽  
Ccd Observations

AbstractA widely used tool in studying quasi-monoperiodic processes is the O–C diagram. This paper deals with the application of this diagram in minor planet studies. The main difference between our approach and the classical O–C diagram is that we transform the epoch (=time) dependence into the geocentric longitude domain. We outline a rotation modelling using this modified O–C and illustrate the abilities with detailed error analysis. The primary assumption, that the monotonity and the shape of this diagram is (almost) independent of the geometry of the asteroids is discussed and tested. The monotonity enables an unambiguous distinction between the prograde and retrograde rotation, thus the four-fold (or in some cases the two-fold) ambiguities can be avoided. This turned out to be the main advantage of the O–C examination. As an extension to the theoretical work, we present some preliminary results on 1727 Mette based on new CCD observations.

A New Approach to the Demonstration of Oxidase-Localization Using Tannic Acid Or Catechin

1973 ◽  
Vol 31 ◽  
pp. 698-699
Author(s):  
V. Mizuhira ◽  
Y. Futaesaku
Keyword(s):  
Cross Section ◽  
Tannic Acid ◽  
Elastic Fiber ◽  
The Other ◽  
New Approach ◽  
Tissue Block ◽  
Active Reaction ◽  
The Cross

Previously we reported that tannic acid is a very effective fixative for proteins including polypeptides. Especially, in the cross section of microtubules, thirteen submits in A-tubule and eleven in B-tubule could be observed very clearly. An elastic fiber could be demonstrated very clearly, as an electron opaque, homogeneous fiber. However, tannic acid did not penetrate into the deep portion of the tissue-block. So we tried Catechin. This shows almost the same chemical natures as that of proteins, as tannic acid. Moreover, we thought that catechin should have two active-reaction sites, one is phenol,and the other is catechole. Catechole site should react with osmium, to make Os- black. Phenol-site should react with peroxidase existing perhydroxide.

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