Optimization of acoustic scattering from dual-frequency driven microbubbles at the difference frequency

2003 ◽  
Vol 113 (6) ◽  
pp. 3073 ◽  
Author(s):  
Matthew Wyczalkowski ◽  
Andrew J. Szeri
Keyword(s):  
Acoustic Scattering ◽  
Difference Frequency ◽  
Dual Frequency ◽  
The Difference

Tunable Far-Infrared Radiation Generated from the Difference Frequency between Two Ruby Lasers

1969 ◽  
Vol 180 (2) ◽  
pp. 363-365 ◽  
Author(s):  
D. W. Faries ◽  
K. A. Gehring ◽  
P. L. Richards ◽  
Y. R. Shen
Keyword(s):  
Infrared Radiation ◽  
Far Infrared ◽  
Difference Frequency ◽  
The Difference ◽  
Far Infrared Radiation

scholarly journals The Radio Reference Frame of the U.S. Naval Observatory Radio Interferometry Program

1991 ◽  
Vol 127 ◽  
pp. 256-260 ◽  
Author(s):  
T.M. Eubanks ◽  
M.S. Carter ◽  
F.J. Josties ◽  
D.N. Matsakis ◽  
D.D. McCarthy
Keyword(s):  
Reference Frames ◽  
Dual Frequency ◽  
Source Position ◽  
The Past ◽  
Naval Observatory ◽  
The Difference ◽  
Rotation Of The Earth ◽  
Celestial Reference System ◽  
Right Ascension ◽  
The U.S

AbstractThe U.S. Naval Observatory Navnet program monitors changes in the rotation of the Earth on a regular basis using radio interferometric observations acquired with telescopes in Alaska, Hawaii, Florida, West Virginia and, in the past, Maryland; other radio telescopes have also participated occasionally. These observations have been used to derive a radio interferometric celestial reference system, Navy 1990-5, using two years of dual frequency measurements from 24-hour-duration observing sessions. A total of 84 extragalactic radio sources, mostly quasars, have been observed by the Navnet program to date, of which 70 currently have source position formal errors of one milli second of arc or less. The root mean square of the difference between source position estimates from the Navnet data and an independently derived catalog using completely different data is less than one milli second of arc in both right ascension and declination after the adjustment of an arbitrary rotational offset between the two celestial reference frames.

DIFFERENCE FREQUENCY HARMONIC ION HEATING

1967 ◽  
Vol 45 (5) ◽  
pp. 1771-1781 ◽  
Author(s):  
C. R. James ◽  
W. B. Thompson
Keyword(s):  
High Frequency ◽  
Collision Frequency ◽  
Difference Frequency ◽  
Fourth Power ◽  
Heating Process ◽  
Ion Heating ◽  
Frequency Signal ◽  
Transverse Waves ◽  
The Difference ◽  
Frequency Harmonic

The heating of a magnetized hot diffuse plasma using the difference frequency signal generated from two high-frequency (35 GHz) transverse waves is examined. The plasma is described by the cold plasma model and a series expansion of harmonics is used to obtain a solution to the equations. It is shown that the energy absorbed by the ions can be made inversely proportional to the collision frequency and the fourth power of the driven frequency and proportional to the fourth power of the driven electric field intensity. An investigation of the sensitivity of the heating process to fluctuations in frequency, density, and d-c. magnetic field is carried out.

Standard‐target calibration of a parametric sonar over the difference‐frequency band, 1–6 kilohertz.

2009 ◽  
Vol 125 (4) ◽  
pp. 2718-2718 ◽  
Author(s):  
Kenneth G. Foote ◽  
Johnny Dybedal ◽  
Eirik Tenningen
Keyword(s):  
Frequency Band ◽  
Difference Frequency ◽  
The Difference ◽  
Parametric Sonar

scholarly journals Nonlinear Resonance of Cavities Filled with Bubbly Liquids: A Numerical Study with Application to the Enhancement of the Frequency Mixing Effect

2018 ◽  
Vol 2018 ◽  
pp. 1-9 ◽  
Author(s):  
María Teresa Tejedor Sastre ◽  
Christian Vanhille
Keyword(s):  
Nonlinear Resonance ◽  
Frequency Component ◽  
Difference Frequency ◽  
Cavity Resonance ◽  
Global Changes ◽  
Nonlinear Frequency ◽  
Pressure Amplitude ◽  
Resonance Shift ◽  
The Difference ◽  
Frequency Mixing

This paper studies the nonlinear resonance of a cavity filled with a nonlinear biphasic medium made of a liquid and gas bubbles at a frequency generated by nonlinear frequency mixing. The analysis is performed through numerical simulations by mixing two source signals of frequencies well below the bubble resonance. The finite-volume and finite-difference based model developed in the time domain simulates the nonlinear interaction of ultrasound and bubble dynamics via the resolution of a differential system formed by the wave and Rayleigh–Plesset equations. Some numerical results, consistent with the literature, validate our procedure. Other results reveal the existence of a frequency shift of the cavity resonance at the difference-frequency component, which rises with pressure amplitude and evidences the global changes undergone by the bubbly medium under finite amplitudes. Finally, this work shows the enhancement of the amplitude of the difference-frequency component generated by parametric excitation using the nonlinear resonance shift, which is more pronounced when the second primary frequency is constant, the first one is varied to match the nonlinear resonance, and both have the same amplitude.

scholarly journals Regiomontan: A Regional High Precision Ionosphere Delay Model and Its Application in Precise Point Positioning

Sensors ◽  
2020 ◽  
Vol 20 (10) ◽  
pp. 2845
Author(s):  
Janina Boisits ◽  
Marcus Glaner ◽  
Robert Weber
Keyword(s):  
Precise Point Positioning ◽  
Ionospheric Delay ◽  
Single Frequency ◽  
External Information ◽  
Delay Model ◽  
Dual Frequency ◽  
Propagation Delays ◽  
Point Positioning ◽  
The Difference ◽  
High Level

Propagation delays of GNSS signals caused by the ionosphere can range up to several meters in zenith direction and need to be corrected. Geodetic receivers observing at two or more frequencies allow the mitigation of the ionospheric effects by forming linear combinations. However, single frequency users depend on external information. The ionosphere delay model Regiomontan developed at TU Wien is a regional ionospheric delay model providing high accuracy information with a latency of only a few hours. The model is based on dual-frequency phase observations of a regional network operated by EPOSA (Echtzeit Positionierung Austria) and partners. The corrections cover a geographical extent for receiver positions within Austria and are provided in the standardized IONEX format. The performance of Regiomontan as well as its application in Precise Point Positioning (PPP) were tested with our in-house PPP software raPPPid using the so-called uncombined model with ionospheric constraint. Various tests, e.g., analyzing the coordinate convergence behavior or the difference between estimated and modeled ionospheric delay, proving the high level of accuracy provided with Regiomontan. We conclude that Regiomontan performs at a similar level of accuracy as IGS final TEC maps, but with explicitly reduced latency.

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