scholarly journals Recognition of wavefront aberrations types corresponding to single Zernike functions from the pattern of the point spread function in the focal plane using neural networks

2020 ◽  
Vol 44 (6) ◽  
pp. 923-930
Author(s):  
I.A. Rodin ◽  
S.N. Khonina ◽  
P.G. Serafimovich ◽  
S.B. Popov

In this work, we carried out training and recognition of the types of aberrations corresponding to single Zernike functions, based on the intensity pattern of the point spread function (PSF) using convolutional neural networks. PSF intensity patterns in the focal plane were modeled using a fast Fourier transform algorithm. When training a neural network, the learning coefficient and the number of epochs for a dataset of a given size were selected empirically. The average prediction errors of the neural network for each type of aberration were obtained for a set of 15 Zernike functions from a data set of 15 thousand PSF pictures. As a result of training, for most types of aberrations, averaged absolute errors were obtained in the range of 0.012 – 0.015. However, determining the aberration coefficient (magnitude) requires additional research and data, for example, calculating the PSF in the extrafocal plane.

2021 ◽  
Vol 2086 (1) ◽  
pp. 012148
Author(s):  
P A Khorin ◽  
A P Dzyuba ◽  
P G Serafimovich ◽  
S N Khonina

Abstract Recognition of the types of aberrations corresponding to individual Zernike functions were carried out from the pattern of the intensity of the point spread function (PSF) outside the focal plane using convolutional neural networks. The PSF intensity patterns outside the focal plane are more informative in comparison with the focal plane even for small values/magnitudes of aberrations. The mean prediction errors of the neural network for each type of aberration were obtained for a set of 8 Zernike functions from a dataset of 2 thousand pictures of out-of-focal PSFs. As a result of training, for the considered types of aberrations, the obtained averaged absolute errors do not exceed 0.0053, which corresponds to an almost threefold decrease in the error in comparison with the same result for focal PSFs.


2019 ◽  
Vol 2019 (02) ◽  
pp. 89-98
Author(s):  
Vijayakumar T

Predicting the category of tumors and the types of the cancer in its early stage remains as a very essential process to identify depth of the disease and treatment available for it. The neural network that functions similar to the human nervous system is widely utilized in the tumor investigation and the cancer prediction. The paper presents the analysis of the performance of the neural networks such as the, FNN (Feed Forward Neural Networks), RNN (Recurrent Neural Networks) and the CNN (Convolutional Neural Network) investigating the tumors and predicting the cancer. The results obtained by evaluating the neural networks on the breast cancer Wisconsin original data set shows that the CNN provides 43 % better prediction than the FNN and 25% better prediction than the RNN.


2019 ◽  
Author(s):  
Daniel Cleather

Musculoskeletal models have been used to estimate the muscle and joint contact forces expressed during movement. One limitation of this approach, however, is that such models are computationally demanding, which limits the possibility of using them for real-time feedback. One solution to this problem is to train a neural network to approximate the performance of the model, and then to use the neural network to give real-time feedback. In this study, neural networks were trained to approximate the FreeBody musculoskeletal model for jumping and landing tasks. The neural networks were better able to approximate jumping than landing, which was probably a result of the greater variability in the landing data set used in this study. In addition, a neural network that was based on a reduced set of inputs was also trained to approximate the outputs of FreeBody during a landing task. These results demonstrate the feasibility of using neural networks to approximate the results of musculoskeletal models in order to provide real-time feedback. In addition, these neural networks could be based upon a reduced set of kinematic variables taken from a 2-dimensional video record, making the implementation of mobile applications a possibility.


Micromachines ◽  
2020 ◽  
Vol 11 (4) ◽  
pp. 437 ◽  
Author(s):  
Vijayakumar Anand ◽  
Tomas Katkus ◽  
Saulius Juodkazis

A new hybrid diffractive optical element (HDOE) was designed by randomly multiplexing an axicon and a Fresnel zone lens. The HDOE generates two mutually coherent waves, namely a conical wave and a spherical wave, for every on-axis point object in the object space. The resulting self-interference intensity distribution is recorded as the point spread function. A library of point spread functions are recorded in terms of the different locations and wavelengths of the on-axis point objects in the object space. A complicated object illuminated by a spatially incoherent multi-wavelength source generated an intensity pattern that was the sum of the shifted and scaled point spread intensity distributions corresponding to every spatially incoherent point and wavelength in the complicated object. The four-dimensional image of the object was reconstructed using computer processing of the object intensity distribution and the point spread function library.


2017 ◽  
Vol 28 (3-4) ◽  
pp. 55-71
Author(s):  
V. R. Cherlіnka

The maіn objectіve was to study the іnfluence of the traіnіng dataset on the qualіtatіve characterіstіcs of sіmulatіve soіl maps, whіch are obtaіned through sіmulatіon usіng a typіcal set of materіals that can be potentіally avaіlable for the soіl scіentіst іn modern Ukraіnіan realіtіes. Achіevement of thіs goal was achіeved by solvіng a number of the followіng tasks: a) dіgіtіzіng of cartographіc materіals; b) creatіng DEM wіth a resolutіon equal to 10 m; c) analysіs of dіgіtal elevatіon models and extractіon of land surface parameters; d) generatіon of traіnіng datasets accordіng to the descrіbed methodologіcal approaches; e) creatіon sіmulatіon models of soіl-cover іn R-statіstіc; g) analysіs of the obtaіned results and conclusіons regardіng the optіmal sіze of the traіnіng datasets for predіctіve modelіng of the soіl cover and іts duratіon. As an object was selected a fragment of the terrіtory of Ukraіne (4200×4200 m) wіthіn the lіmіts of Glybotsky dіstrіct of the Chernіvtsі regіon, confіned to the Prut-Sіret іnterfluve (North Bukovyna) wіth contrast geomorphologіcal condіtіons. Thіs area has dіfferent admіnіstratіve subordіnatіon and economіc use but іs covered wіth soіl cartographіc materіals only by 49.43 %. For data processіng were used іnstrumental possіbіlіtіes of free software: geo- rectіfіcatіons of maps materіal – GІS Quantum, dіgіtalіzatіon – Easy Trace, preparatіon of maps morphometrіc parameters – GRASS GІS and buіldіng sіmulatіve soіl maps – R, a language and envіronment for statіstіcal computіng. To create sіmulatіon models of soіl cover, a R-statіstіc scrіpt was wrіtten that іncludes a number of adaptatіons for solvіng set tasks and іmplements the dіfferent types of predіcatіve algorіthms such as: Multіnomіal Logіstіc Regressіon, Decіsіon Trees, Neural Networks, Random Forests, K-Nearest Neіghbors, Support Vector Machіnes and Bagged Trees. To assess the qualіty of the obtaіned models, the Cohen’s Kappa Іndex (?) was used whіch best represents the degree of complіance between the orіgіnal and the sіmulated data. As a benchmark, the usual medіal axes traіnіng dataset of was used. Other study optіons were: medіan-weіghted and randomіzed-weіghted samplіng. Thіs together wіth 7 predіcatіve algorіthms allowed to get 72 soіl sіmulatіons, the analysіs of whіch revealed quіte іnterestіng patterns. Models rankіng by іncreasіng the qualіty of the predіctіon by the kappa of the maіn data set shown, that the MLR algorіthm showed the worst results among others. Next іn ascendіng order are Neural Network, SVM, KNN, BGT, RF, DT. The last three algorіthms refer to the classіfіcatіon and theіr hіgh results іndіcate the greatest suіtabіlіty of such approaches іn sіmulatіon of soіl cover. The sample based on the weіghted medіan dіd not show strong advantages over others, as the results are quіte controversіal. Only іn the case of the neural network and the Bugget Trees the results of the medіan-weіghted sample predіctіon showed a better result vs a sіmple medіan sample and much worse than any varіants of randomіzed traіnіng data. Other algorіthms requіred a dіfferent number of randomіzed poіnts to cross the 90 % kappa: KNN – 25 %; BGT, RF and DT – 90 %. To achіeve 95 % kappa BGT algorіthm requіres 30% traіnіng poіnts of the total, RF – 25 % and DT – 20 %. Decіsіon Trees as a result turned out to be the most powerful algorіthm, whіch was able to sіmulate the dіstrіbutіon of soіl abnormalіtіes from kappa 97.13 % wіth 35 % saturatіon of the traіnіng sample wіth the orіgіnal data. Overall, DT shows a great dіfference between the approaches to selectіng traіnіng data: any medіan falls by 13 % іn front of a sіmple 5 % randomіzed-weіghted set of traіnіng cells and 22 % – about 35 % of the set.


Author(s):  
Metin DEMIRTAS ◽  
Musa ALCI

The aim of this paper is to compare the neural network and fuzzy modeling approaches on a nonlinear system. We have taken Permanent Magnet Brushless Direct Current (PMBDC) motor data and have generated models using both approaches. The predictive performance of both methods was compared on the data set for model configurations.The paper describes the results of these tests and discusses the effects of changing model parameters on predictive and practical performance. Modeling sensitivity was used to compare for two methods. 


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