Adapting amplitude modulation to plane-wave non-linear Doppler imaging

2014 ◽  
Author(s):  
Charles Tremblay-Darveau ◽  
Ross Williams ◽  
Ze Zhang ◽  
Laurent Milot ◽  
Matthew Bruce ◽  
...  
Keyword(s):  
Plane Wave ◽  
Amplitude Modulation ◽  
Doppler Imaging ◽  
Non Linear

Visualizing the Tumor Microvasculature With a Nonlinear Plane-Wave Doppler Imaging Scheme Based on Amplitude Modulation

2016 ◽  
Vol 35 (2) ◽  
pp. 699-709 ◽  
Author(s):  
Charles Tremblay-Darveau ◽  
Ross Williams ◽  
Laurent Milot ◽  
Matthew Bruce ◽  
Peter N. Burns
Keyword(s):  
Plane Wave ◽  
Amplitude Modulation ◽  
Doppler Imaging ◽  
Tumor Microvasculature ◽  
Nonlinear Plane

scholarly journals Experimental Evaluation of Distortion in Amplitude Modulation Techniques for Parametric Loudspeakers

2020 ◽  
Vol 10 (6) ◽  
pp. 2070
Author(s):  
Ricardo San Martín ◽  
Pablo Tello ◽  
Ana Valencia ◽  
Asier Marzo
Keyword(s):  
Frequency Response ◽  
Amplitude Modulation ◽  
Experimental Evaluation ◽  
Harmonic Distortion ◽  
Intermodulation Distortion ◽  
Simple Method ◽  
Modulation Techniques ◽  
Audible Sound ◽  
Non Linear

Parametric loudspeakers can generate a highly directional beam of sound, having applications in targeted audio delivery. Audible sound modulated into an ultrasonic carrier will get self-demodulated along the highly directive beam due to the non-linearity of air. This non-linear demodularization should be compensated to reduce audio distortion, different amplitude modulation techniques have been developed during the last years. However, some studies are only theoretical whereas others do not analyze the audio distortion in depth. Here, we present a detailed experimental evaluation of the frequency response, harmonic distortion and intermodulation distortion for various amplitude modulation techniques applied with different indices of modulation. We used a simple method to measure the audible signal that prevents the saturation of the microphones when the high levels of the ultrasonic carrier are present. This work could be useful for selecting predistortion techniques and indices of modulation for regular parametric arrays.

A beamforming method for plane wave Doppler imaging of high flow velocities

2016 ◽  
Author(s):  
Omar Mansour ◽  
Tamie L. Poepping ◽  
James C. Lacefield
Keyword(s):  
Plane Wave ◽  
High Flow ◽  
Doppler Imaging ◽  
Flow Velocities

On a non-linear integral equation occurring in diffraction theory

1966 ◽  
Vol 62 (2) ◽  
pp. 249-261 ◽  
Author(s):  
R. F. Millar
Keyword(s):  
Functional Equation ◽  
Integral Equation ◽  
Radiative Transfer ◽  
Plane Wave ◽  
Admissible Solution ◽  
Diffraction Theory ◽  
Linear Integral Equation ◽  
Non Linear Equation ◽  
Non Linear ◽  
Linear Integral

AbstractThe problem of diffraction of a plane wave by a semi-infinite grating of iso-tropic scatterers leads to the consideration of a non-linear integral equation. This bears a resemblance to Chandrasekhar's integral equation which arises in the study of radiative transfer through a semi-infinite atmosphere. It is shown that methods which have been used with success to solve Chandrasekhar's equation are equally useful here. The solution to the non-linear equation satisfies a more simple functional equation which may be solved by factoring (in the Wiener-Hopf sense) a given function. Subject to certain additional conditions which are dictated by physical considerations, a solution is obtained which is the unique admissible solution of the non-linear integral equation. The factors and solution are found explicitly for the case which corresponds to closely spaced scatterers.

scholarly journals Zeeman-Doppler imaging: old problems and new methods

2008 ◽  
Vol 4 (S259) ◽  
pp. 633-644 ◽  
Author(s):  
Thorsten A. Carroll ◽  
Markus Kopf ◽  
Klaus G. Strassmeier ◽  
Ilya Ilyin
Keyword(s):  
Radiative Transfer ◽  
Principal Component ◽  
Magnetic Surface ◽  
Least Square ◽  
Doppler Imaging ◽  
Inversion Method ◽  
Reconstruction Process ◽  
Physical Constraints ◽  
Non Linear ◽  
Transfer Method

AbstractZeeman-Doppler Imaging (ZDI) is a powerful inversion method to reconstruct stellar magnetic surface fields. The reconstruction process is usually solved by translating the inverse problem into a regularized least-square or optimization problem. In this contribution we will emphasize that ZDI is an inherent non-linear problem and the corresponding regularized optimization is, like many non-linear problems, potentially prone to local minima. We show how this problem will be exacerbated by using an inadequate forward model. To facilitate a more consistent full radiative transfer driven approach to ZDI we describe a two-stage strategy that consist of a principal component analysis (PCA) based line profile reconstruction and a fast approximate polarized radiative transfer method to synthesize local Stokes profiles. Moreover, we introduce a novel statistical inversion method based on artificial neural networks (ANN) which provide a fast calculation of a first guess model and allows to incorporate better physical constraints into the inversion process.

In vivo out-of-plane Doppler imaging based on ultrafast plane wave imaging

2013 ◽  
Author(s):  
Bruno-Felix Osmanski ◽  
Gabriel Montaldo ◽  
Mathias Fink ◽  
Mickael Tanter
Keyword(s):  
Plane Wave ◽  
Doppler Imaging ◽  
Out Of Plane ◽  
Wave Imaging

Combined perfusion and doppler imaging using plane-wave nonlinear detection and microbubble contrast agents

2014 ◽  
Vol 61 (12) ◽  
pp. 1988-2000 ◽  
Author(s):  
Charles Tremblay-Darveau ◽  
Ross Williams ◽  
Laurent Milot ◽  
Matthew Bruce ◽  
Peter N. Burns
Keyword(s):  
Plane Wave ◽  
Contrast Agents ◽  
Doppler Imaging ◽  
Microbubble Contrast Agents ◽  
Nonlinear Detection
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