A direct reconstruction technique to retrieve phase in a non-linear curvature wavefront sensor

2018 ◽  
Author(s):  
Michael D. Oliker ◽  
Mala Mateen
Keyword(s):  
Wavefront Sensor ◽  
Reconstruction Technique ◽  
Non Linear

scholarly journals The AOLI low-order non-linear curvature wavefront sensor: a method for high sensitivity wavefront reconstruction

2012 ◽  
Author(s):  
Jonathan Crass ◽  
Peter Aisher ◽  
Bruno Femenia ◽  
David L. King ◽  
Craig D. Mackay ◽  
...  
Keyword(s):  
High Sensitivity ◽  
Wavefront Sensor ◽  
Wavefront Reconstruction ◽  
Non Linear ◽  
Low Order

scholarly journals Comparison of Algebraic Reconstruction Technique Methods and Generative Adversarial Network in Image Reconstruction of Magnetic Induction Tomography (MIT)

2021 ◽  
Vol 2071 (1) ◽  
pp. 012044
Author(s):  
A J Lubis ◽  
N F Mohd Nasir ◽  
Z Zakaria ◽  
M Jusoh ◽  
M M Azizan ◽  
...  
Keyword(s):  
Neural Network ◽  
Regularization Method ◽  
Tikhonov Regularization Method ◽  
Reconstruction Technique ◽  
Algebraic Reconstruction Technique ◽  
Training Process ◽  
Generative Adversarial Network ◽  
Adversarial Network ◽  
Non Linear ◽  
Magnetic Induction Tomography

Abstract Magnetic induction tomography (MIT) is a technique used for imaging electromagnetic properties of objects using eddy current effects. The non-linear characteristics had led to more difficulties with its solution especially in dealing with low conductivity imaging materials such as biological tissues. Two methods that could be applied for MIT image processing which is the Generative Adversarial Network (GAN) and the Algebraic Reconstruction Technique (ART). ART is widely used in the industry due to its ability to improve the quality of the reconstructed image at a high scanning speed. GAN is an intelligent method which would be able to carry out the training process. In the GAN method, the MIT principle is used to find the optimum global conductivity distribution and it is described as a training process and later, reconstructed by a generator. The output is an approximate reconstruction of the distribution’s internal conductivity image. Then, the results were compared with the previous traditional algorithm, namely the regularization algorithm of BPNN and Tikhonov Regularization method. It turned out that GAN had able to adjust the non-linear relationship between input and output. GAN was also able to solve non-linear problems that cannot be solved in the previous traditional algorithms, namely Back Propagation Neural Network (BPNN) and Tikhonov Regularization method. There are several other intelligent algorithms such as CNN (Convolution Neural Network) and K-NN (K-Nearest Neighbor), but such algorithms have not been able to produce the expected image quality. Thus, further study is still needed for the improvement of the image quality. The expected result in this study is the comparison of these two techniques, namely ART and GAN to get the best results on the image reconstruction using MIT. Thus, it is shown that GAN is a better candidate for this purpose.

scholarly journals COSMIC BIRTH: Efficient Bayesian Inference of the Evolving Cosmic Web from Galaxy Surveys

2020 ◽  
Author(s):  
Francisco-Shu Kitaura ◽  
Metin Ata ◽  
Sergio A Rodríguez-Torres ◽  
Mónica Hernández-Sánchez ◽  
A Balaguera-Antolínez ◽  
...  
Keyword(s):  
Dark Matter ◽  
Bayesian Inference ◽  
Light Cone ◽  
Initial Conditions ◽  
Mass Matrix ◽  
Matter Field ◽  
Density Field ◽  
Reconstruction Technique ◽  
Galaxy Surveys ◽  
Non Linear

Abstract We present COSMIC BIRTH: COSMological Initial Conditions from Bayesian Inference Reconstructions with THeoretical models: an algorithm to reconstruct the primordial and evolved cosmic density fields from galaxy surveys on the light-cone. The displacement and peculiar velocity fields are obtained from forward modelling at different redshift snapshots given some initial cosmic density field within a Gibbs-sampling scheme. This allows us to map galaxies, observed in a light-cone, to a single high redshift and hereby provide tracers and the corresponding survey completeness in Lagrangian space including tetrahedral tessellation mapping. These Lagrangian tracers in turn permit us to efficiently obtain the primordial density field, making the COSMIC BIRTH code general to any structure formation model. Our tests are restricted for the time being to Augmented Lagrangian Perturbation theory. We show how to robustly compute the non-linear Lagrangian bias from clustering measurements in a numerical way, enabling us to get unbiased dark matter field reconstructions at initial cosmic times. We also show that we can accurately recover the information of the dark matter field from the galaxy distribution based on a detailed simulation. Novel key ingredients to this approach are a higher-order Hamiltonian sampling technique and a non-diagonal Hamiltonian mass-matrix. This technique could be used to study the Eulerian galaxy bias from galaxy surveys and could become an ideal baryon acoustic reconstruction technique. In summary, this method represents a general reconstruction technique, including in a self-consistent way a survey mask, non-linear and non-local bias and redshift space distortions, with an efficiency about 10 times superior to previous comparable methods.

A non-linear curvature wavefront sensor reconstruction speed and the broadband design

2011 ◽  
Author(s):  
Mala Mateen ◽  
Olivier Guyon ◽  
José Sasián ◽  
Vincent Garrel ◽  
Michael Hart
Keyword(s):  
Wavefront Sensor ◽  
Non Linear

Detecting non-linear sea-level variations in tide gauge records: a study case along the Dutch coast.

2020 ◽  
Author(s):  
Riccardo Riva ◽  
David Steffelbauer ◽  
Jan Kwakkel ◽  
Jos Timmermans ◽  
Mark Bakker
Keyword(s):  
Sea Level ◽  
Tide Gauge ◽  
Accurate Determination ◽  
Ocean Dynamics ◽  
Atmospheric Effects ◽  
Reconstruction Technique ◽  
Tide Gauge Records ◽  
Dutch Coast ◽  
Non Linear ◽  
Global Mean

<p>Tide gauges are the main source of information about sea-level changes in the Industrial Age. When looking at global mean values, century-long reconstructions produce rates between 1-2 mm/yr, while estimates over the last three decades reveal a much faster rise of about 3 mm/yr, as also indicated by satellite altimetry observations. In spite of this evidence for a recent acceleration, its quantification remains a challenging and relevant task, because results are highly dependent on the length of the record and on the reconstruction technique, whereas decision makers require clear proof to legitimise action.</p><p>While global mean results are very important to understand climate change, regional to local variations are more relevant for the purpose of planning mitigation and adaptation measures. However, mainly due to natural variability, looking at individual tide gauge stations hampers the accurate determination of linear and non-linear trends.</p><p>We analyse tide gauge records along the Dutch coast by means of advanced statistical techniques, with the main objective of determining whether and under which conditions it is possible to detect departures from secular trends. We particularly focus on how to handle noise in the natural system, which for the Dutch coast is mainly represented by local atmospheric effects and by variability in ocean dynamics in the NE Atlantic.</p>

scholarly journals Development of the Non-linear Curvature Wavefront Sensor

2017 ◽  
Author(s):  
Mala Mateen ◽  
Johanan Codona ◽  
Olivier Guyon
Keyword(s):  
Wavefront Sensor ◽  
Non Linear

B. The Non-Linear Calculations for Pulsating Stars

1967 ◽  
Vol 28 ◽  
pp. 105-176
Author(s):  
Robert F. Christy
Keyword(s):  
Major Part ◽  
Afternoon Session ◽  
Discussion Session ◽  
Pulsating Stars ◽  
Fourth Symposium ◽  
Non Linear ◽  
Considerable Discussion ◽  
Informal Approach ◽  
Preceding Session

(Ed. note: The custom in these Symposia has been to have a summary-introductory presentation which lasts about 1 to 1.5 hours, during which discussion from the floor is minor and usually directed at technical clarification. The remainder of the session is then devoted to discussion of the whole subject, oriented around the summary-introduction. The preceding session, I-A, at Nice, followed this pattern. Christy suggested that we might experiment in his presentation with a much more informal approach, allowing considerable discussion of the points raised in the summary-introduction during its presentation, with perhaps the entire morning spent in this way, reserving the afternoon session for discussion only. At Varenna, in the Fourth Symposium, several of the summaryintroductory papers presented from the astronomical viewpoint had been so full of concepts unfamiliar to a number of the aerodynamicists-physicists present, that a major part of the following discussion session had been devoted to simply clarifying concepts and then repeating a considerable amount of what had been summarized. So, always looking for alternatives which help to increase the understanding between the different disciplines by introducing clarification of concept as expeditiously as possible, we tried Christy's suggestion. Thus you will find the pattern of the following different from that in session I-A. I am much indebted to Christy for extensive collaboration in editing the resulting combined presentation and discussion. As always, however, I have taken upon myself the responsibility for the final editing, and so all shortcomings are on my head.)

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