scholarly journals Inverse problems of sounding pulse formation in ultrasound tomography: mathematical modeling and experiments

Author(s):  
А.В. Гончарский ◽  
С.Ю. Романов ◽  
С.Ю. Серёжников

Статья посвящена разработке методов формирования акустических зондирующих импульсов в задачах ультразвуковой томографии. Обратная задача формирования акустических зондирующих импульсов рассматривается в рамках линейной модели. Эта задача является некорректной и требует использования регуляризирующих алгоритмов. Для численного решения использована тихоновская схема регуляризации. Разработанные алгоритмы протестированы на решении модельных задач и с помощью специально поставленного эксперимента, в котором акустический тракт включает в себя цифровой генератор импульсов, усилитель, источник акустического излучения, акустический детектор, предусилитель и аналого-цифровой преобразователь. Экспериментально подтверждены как адекватность линейной модели, так и высокая эффективность предложенных алгоритмов. This paper is concerned with developing the methods of forming acoustic sounding pulses in ultrasound tomography applications. The inverse problem of forming acoustic sounding pulses is considered in the framework of linear models. This problem is ill-posed and requires the use of regularizing algorithms. Tikhonov's regularization scheme is used to solve the problem numerically. The developed algorithms are tested on model problems as well as on experimental data. In the experimental setup, the acoustic path includes a digital waveform generator, an amplifier, an ultrasound emitter, a hydrophone with a preamplifier, and an analog-digital converter. The applicability of the linear model and the efficiency of the proposed algorithms are substantiated experimentally.

2009 ◽  
Vol 79 (6) ◽  
pp. 722-727 ◽  
Author(s):  
Abdelnasser Dahmani ◽  
Ahmed Ait Saidi ◽  
Fatah Bouhmila ◽  
Mouloud Aissani

2016 ◽  
Vol 833 ◽  
pp. 170-175 ◽  
Author(s):  
Andrew Sia Chew Chie ◽  
Kismet Anak Hong Ping ◽  
Yong Guang ◽  
Ng Shi Wei ◽  
Nordiana Rajaee

The inverse scattering in time domain known as Forward-Backward Time-Stepping (FBTS) technique is applied to determine the sizes, shape and location of the embedded objects. Tikhonov’s regularization method has been proposed in order to improve or solve the ill-posed of FBTS inverse scattering problem. The reconstructed results showed that FBTS technique can detect the presence of embedded objects. The reconstructed results of FBTS technique utilizing with the Tikhonov’s regularization method shown better results than the results only applied FBTS technique. Tikhonov’s regularization combined with FBTS technique to improve the quality of image reconstruction.


2018 ◽  
Vol 26 (2) ◽  
pp. 277-286 ◽  
Author(s):  
Jens Flemming

AbstractVariational source conditions proved to be useful for deriving convergence rates for Tikhonov’s regularization method and also for other methods. Up to now, such conditions have been verified only for few examples or for situations which can be also handled by classical range-type source conditions. Here we show that for almost every ill-posed inverse problem variational source conditions are satisfied. Whether linear or nonlinear, whether Hilbert or Banach spaces, whether one or multiple solutions, variational source conditions are a universal tool for proving convergence rates.


2014 ◽  
Vol 23 (2) ◽  
pp. 116-131 ◽  
Author(s):  
E. Chernousova ◽  
Yu. Golubev
Keyword(s):  

2014 ◽  
Vol 2014 ◽  
pp. 1-7 ◽  
Author(s):  
Tao Min ◽  
Weimin Fu ◽  
Qiang Huang

We investigate the inverse problem in the nonhomogeneous heat equation involving the recovery of the initial temperature from measurements of the final temperature. This problem is known as the backward heat problem and is severely ill-posed. We show that this problem can be converted into the first Fredholm integral equation, and an algorithm of inversion is given using Tikhonov's regularization method. The genetic algorithm for obtaining the regularization parameter is presented. We also present numerical computations that verify the accuracy of our approximation.


2015 ◽  
Vol 24 (1) ◽  
pp. 1-15 ◽  
Author(s):  
Yu. Golubev ◽  
T. Zimolo
Keyword(s):  

2018 ◽  
Vol 14 (24) ◽  
pp. 464
Author(s):  
Saturnin Azonkpin ◽  
Daniel Chèpo Chougourou ◽  
Aimé H. Bokonon-Ganta ◽  
Joseph Dossou ◽  
Léonard E. Ahoton ◽  
...  

Cotton remains the main source of foreign exchange for Benin. This study aims to contribute to increased yield of organic cotton through the evaluation of the effectiveness of cashew balm as an alternative method of management of carpophagous pests of cotton. The experimental setup consists of Fisher Blocks with 6 objects in 4 repetitions. The objects compared are '' Unprocessed '', the Agri-bio-pesticide dosed at 1 l / ha, two concentrations (1% and 2%) of the hot and cold-extracted cashew balm. Linear mixed or fixed effects models and generalized linear models with mixed or fixed effects were used to determine the influence of the objects on the carpophagous larva and their damage in 2015 and 2016 in Thya to the north of Benin. The number of Helicoverpa armigera larva found in 30 plants ranged from 1.2 (Agri-biopesticide) to 2.3 (Untreated) in 2015. The percentages of green capsules with holes varied by 36.08% (Agri-bio-pesticide) at 53.68% (1% cold-extracted balm) in 2015. The percentages of ripe capsules with holes varied from 32.05% (hot-pressed balm at 2%) to 45.00% (Untreated) in 2016. Seed cotton yield ranged from 229.91 kg / ha (Untreated) to 500 kg / ha (Agri-biopesticide) in 2016. It is noted that Agri-bio-pesticide and the 2% dose of cashew balm, were more effective than that of 1%. The cashew balm is positioned as an alternative to biopesticides used in organic cotton farming.


Author(s):  
B. Roy Frieden

Despite the skill and determination of electro-optical system designers, the images acquired using their best designs often suffer from blur and noise. The aim of an “image enhancer” such as myself is to improve these poor images, usually by digital means, such that they better resemble the true, “optical object,” input to the system. This problem is notoriously “ill-posed,” i.e. any direct approach at inversion of the image data suffers strongly from the presence of even a small amount of noise in the data. In fact, the fluctuations engendered in neighboring output values tend to be strongly negative-correlated, so that the output spatially oscillates up and down, with large amplitude, about the true object. What can be done about this situation? As we shall see, various concepts taken from statistical communication theory have proven to be of real use in attacking this problem. We offer below a brief summary of these concepts.


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