Wyniki 1-10 spośród 34 dla zapytania: authorDesc:"Tomasz RYMARCZYK"

Topological Methods to Determine Damages of Flood Embankments DOI:10.15199/48.2016.12.39

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This paper presents a method of testing flood embankment. There was used a specially built laboratory model to determine the moisture level of flood embankments. The finite element method was used to solve the forward problem. The proposed algorithm was initialized by using one step methods and topological sensitivity analysis. There was solved the inverse problem in order to visualize moisture inside objects. There was made possible to change topology during the optimization. The level set method and the Gauss-Newton method have been applied very successfully in many areas of the scientific modelling. Topological algorithms were based on shape sensitivity include the boundary design of the elastic interface. These algorithms are a relatively new procedure to overcome this problem. Streszczenie. Artykuł przedstawia metodę badania wału przeciwpowodziowego. Został zbudowany specjalny model laboratoryjny wału w celu określenia poziomu wilgotności. Do rozwiązania zagadnienia prostego została wykorzystana metoda elementów skończonych. Proponowany algorytm inicjowany jest metodą jednokrokową i rozwiązywany topologiczną analizą wrażliwościową. Rozwiązano zagadnienie odwrotne w celu wizualizacji wilgoci wewnątrz obiektów, poprzez zmianę topologii podczas procesu optymalizacji. Metody zbiorów poziomicowych i Gaussa-Newtona stosuje się z dużym powodzeniem w wielu dziedzinach modelowania naukowego. Metody topologiczne opierają się na analizie wrażliwościowej dostosowując kształt brzegu elastycznego interfejsu. Algorytmy te są relatywnie nowymi rozwiązaniami dla tego typu problemu. (Metody topologiczne do określania uszkodzeń w wałach przeciwpowodziowych). Keywords: Electrical Impedance Tomography, Finite Element Method, Inverse Problem Słowa kluczowe: elektryczna tomografia impedancyjna, metoda elementów skończonych, zagadnienie odwrotne Introduction This paper presents the new method examining the flood embankment dampness by electrical impedance t[...]

e-Medicus System to Segmentation and Analysis Medical Images DOI:10.15199/48.2017.01.48

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In this work, there was presented authoring system to exam the medical images by using statistical methods, topological algorithms and computational intelligence methods. These methods are used to identify the properties for the images. There was prepared a special e-Medicus system to machine learning, analysis and compare data and pictures. The solution shows the architecture of the system collecting and analysing data. There was tried to develop an algorithm for level set method (LSM) applied to piecewise constant image segmentation. These algorithms are needed to identify arbitrary number of phases for the segmentation problem. The image segmentation refers to the process of partitioning a digital image into multiple regions. There is typically used to locate objects and boundaries in images. Streszczenie. W artykule, został przedstawiony autorski system do badania obrazów medycznych przy użyciu metod statystycznych, algorytmów inteligencji obliczeniowej i metod topologicznych. Metody te stosuje się w celu identyfikowania właściwości obrazów. Przygotowano specjalny system e-Medicus do uczenia maszynowego, analizy i porównywania danych i obrazów. Rozwiązanie przedstawia architekturę systemu do gromadzenia i analizy danych. Opracowano algorytmy oparte na metodzie zbiorów poziomicowych (MZP) jako odcinkowo stałej segmentacji obrazu. Algorytmy te są potrzebne do identyfikacji dowolnej liczby faz dla problemu segmentacji, która odnosi się do procesu dzielenia cyfrowego obrazu w różnych regionach. Używana jest zwykle do lokalizacji obiektów i brzegów w obrazach. (System e-Medicus do segmentacji i analizy obrazów medycznych). Keywords: Electrical Impedance Tomography, Image Analysis, Level Set Method Słowa kluczowe: tomografia impedancyjna, analiza obrazów, metoda zbiorów poziomicowych Introduction In medical clinical research and practice, imaging has become an essential part to diagnose and to study anatomy and function of the human body. T[...]

EIT detection methods of damage in landfills and flood embankments DOI:10.15199/48.2019.05.13

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The presented article describes a group of innovative methods enabling the identification of damage to landfills and flood embankments. These are methods based on electrical impedance tomography (EIT) [1], however, significantly improved by using original algorithms that enable reconstruction of tomographic images. In this study, three types of hybrid algorithms were considered:  generalized linear regression (GLR) [2],  generalized linear regression with stepwise regression (GLR-SR),  ElasticNET [3]. All three of the above statistical methods were used to reduce the number of predictors. In the considered EIT system, the input vector consists of 192 values of voltage drops taken due to the arrangement of 16 electrodes. The input vector reduced in this way was further used to train the artificial neural networks system (ANN) [4]. Among the tomographic methods, apart from the EIT, one can also be distinguished: electrical capacitance tomography [5-9], magnetoacoustics [10], multipath tomography [11] and others. In order to improve the imaging quality, various methods are used, mostly based on modern information techniques: fuzzy logic [12], GPU parallel computing [13], integer linear programming [14], etc. Flood is one of the most common and frequent natural disasters. Floods are the cause of many human dramas. One of the ways to protect the floodplains near landfills, rivers and water banks is to lift flood embankments. Thanks to this, you can temporarily raise the level of freshet over the main river bed and suppress the flood. However, higher water level accelerates the erosion of the top of the embankment or landfill barrier and can destroy it. In addition, given the insufficient filtration power of the embankment body, high water can lead to an increase in the number of leaks, which may lead to partial destruction of the flood bank. Despite significant achievements in the design of safe bunds[...]

The use of elastic net and neural networks in industrial process tomography DOI:10.15199/48.2019.05.15

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Industrial Process Tomography (IPT) is a non-invasive and non-destructive imaging [1] technique used in various industries for processes in which knowledge about the interior of the object is required [2], [3]. A common reason for using IPT is that it plays an important role in the continuous monitoring of systems, allowing better understanding and ensuring the quality of industrial processes. IPT provides fast and dynamic response, facilitates process control, including on-line, enables error detection and system failures in real time [4]. In addition, thanks to IPT, the process characteristics can be quantified, with data included in the overall process control strategy. Finally, IPT provides robust experimental means to optimize the design and operation of a process tank or pipeline by developing a model and validation. Industrial process tomography (IPT) applications are usually a challenge for obtaining spatial data from observation beyond the boundaries of the process. The wireless sensor network technology with their return loops will be the basis for production control. The decisive difference in mass production of chemicals, metals, building materials, food and other goods is that common process sensors provide only local measurements such as temperature, pressure, fill level, flow rate or species concentration. However, in most production systems, such local measurements are not representative of the overall process and therefore spatial solutions are needed. Here the future belongs to the dispersed and imaging sensors. The tomograph can be adapted to the requirements of a given company and to the specifics of a given industry. The prepared solution can effectively support the quality of products in automated production lines by identifying shapes, detecting cracks and damage, and presenting three-dimensional visualization of industrial processes. This is especially important for dairy producers, where the foami[...]

Minimization of Objective Function in Electrical Impedance Tomography by Topological Derivative DOI:10.15199/48.2019.06.25

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Electrical impedance tomography (EIT) is a non-invasive problem of image reconstruction in which the distribution of conductivity in an object domain can be reconstructed using external voltage measurements. EIT is an imaging technique with existing and potential uses in engineering and medical problems. In this method, electric currents are injected into a conductive object through electrodes placed on its surface, and the resulting electrical potential on the electrodes is determined. In the opposite case, the objective function is minimized in an iterative procedure, using the measured and modeled data, the internal conductivity profile is calculated. Electric tomography can be used in industrial, medical and geophysical applications. Recently, there has been a dramatic increase in the field of chest imaging, with an emphasis on lung ventilation and heart rhythm monitoring. The finite element method was applied to domain modeling, and topological algorithms were used to solve the inverse problem [21]. The problem of topology optimization applied in the EIT is to find the conductivity distribution of the object, which minimizes the difference between electrical potentials obtained from measurements of electrodes at the boundary of the object and numerically simulated electrical potentials [3,4,8,14-16]. Topological Derivative The optimization problem is usually defined as the minimization of a given activity [2,6,9-11,13,22]. Shape derivatives and topological derivatives have been included in the level determination methods to investigate problems related to shape optimization [17, 18]. The basic method of shape optimization is a topological derivative evaluated for a given functional shape defined in the geometric field and dependent on the classical solution of the elliptical problem of the limit of value. The topological derivative is defined as the first term of asymptotic expansi[...]

Dobór metod pomiarowych i algorytmów rekonstrukcji obrazu do badania stanu pni drzew

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W pracy przedstawiono metodę badania stanu pni drzew wykorzystującą tomografie impedancyjną do odtworzenia właściwości obiektu. Algorytm rekonstrukcji polega na rozwiązaniu zagadnienia odwrotnego z wykorzystaniem metody zbiorów poziomicowych i metody elementów skończonych. W procesie iteracyjnym wielokrotnie rozwiązywane jest zagadnienie proste, dopóki obliczony rozkład napięć nie osiągnie wartości maksymalnie zbliżonych napięć zmierzonych. Abstract. In this work was shown a method to examine the non-destructive analysis defects of tree trunks by solving the inverse problem in the electrical impedance tomography. The measurements use point-like electrodes at the boundary of the object. By two of these current are injected. The conductivity values in different regions are determined by the finite element method. The representation of the boundary shape and its evolution during an iterative reconstruction process is achieved by the level set method. (Choice of algorithms to image reconstruction and measurement methods to examine defects of tree trunks). Słowa kluczowe: metody optymalizacyjne, tomografia impedancyjna, zagadnienie odwrotne Keywords: Optimization Methods, Electrical Impedance Tomography, Inverse Problem Wstęp Uwzględniając coraz ostrzejsze współczesne wymogi bezpieczeństwa i ekologii, poszukuje się dokładnych i niedrogich sposobów monitorowania stanu pni starodrzewia lub drzew w szczególności w aglomeracjach miejskich. Zdolność drzewa do przewodzenia prądu elektrycznego zależy od chemicznych właściwości drewna, takich jak: zawartość wody w tkankach, struktura komórek, itp. Wszystkie te właściwości ulegają zmianie, jeżeli w drzewie występuje zgnilizna, grzyb, próchnica lub przemarznięcie czy też mamy do czynienia z mokrym drewnem, kiedy to obszar o podwyższonej wilgotności przejawia się niskim oporem elektrycznym. W pracy zaproponowano zastosowanie tomografii impedancyjnej do takich badań, a obrazowanie stanu pni przedst[...]

The Shape Reconstruction of Unknown Objects for Inverse Problems

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The proposed solution of the inverse problem in the Electrical Impedance Tomography was based on a numerical scheme for the identification of the piecewise constant conductivity. The level set method is a powerful tool for representing moving of stationary interfaces. The representation of the shape of the boundary and its evolution during an iterative reconstruction process is achieved by the level set function. The forward problem was solved by the finite element method. The iterative algorithms are based a combination of the these methods. Streszczenie. Proponowane rozwiązanie zagadnienia odwrotnego w tomografii impedancyjnej zostało oparte na algorytmach numerycznych identyfikujących obiekty o różnych konduktywnościach. Reprezentację kształtu brzegu oraz jego ewolucję podczas procesu rekonstrukcji opisuje metoda zbiorów poziomicowych. Zagadnienie proste zostało rozwiązane za pomocą metody elementów skończonych. Rozwiązanie zagadnienia odwrotnego oparte zostało na odpowiednim złożeniu wymienionych metod. (Rekonstrukcja kształtu nieznanych obiektów w zagadnieniach odwrotnych). Keywords: Electrical Impedance Tomography, Level Set Methods, Inverse Problem Słowa kluczowe: tomografia impedancyjna, metoda zbiorów poziomicowych, zagadnienie odwrotne Electrical Impedance Tomography In this paper was proposed the topological numerical technique with different advantages to solve the inverse problem in the electrical impedance tomography (EIT) [2,7- 9]. The level set method is known to be a powerful and versatile tool to model the evolution of interfaces [1,3,4]. The idea is merely to define a smooth function ϕ, that represents the interface and has the following properties (fig.1): [...]

Measurement Methods and Image Reconstruction in Electrical Impedance Tomography

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In this work was shown a method to examine the non-destructive analysis defects of the objects by solving the inverse problem in the electrical impedance tomography. The measurements use point-like electrodes at the boundary of the object. By two of these current are injected. The representation of the shape of the boundary and its evolution during an iterative reconstruction process is achieved by the level set function and Chan-Vese model. The forward problem was solved by the finite element method. Streszczenie. W pracy zaprezentowano dwie metody pomiarów tomograficznych wybranych obiektów oraz rekonstrukcje obrazów ich nieznanych właściwości w wyniku rozwiązania zagadnienia odwrotnego. Algorytm rekonstrukcji oparty został na idei zbiorów poziomicowych a do rozwiązania zagadnienia prostego wykorzystano metodę elementów skończonych. Reprezentację wyglądu obrazu badanego obiektu wykonano rozwiązując wielokrotnie zadanie proste tak, aby w procesie iteracyjnym otrzymać rozkład napięć maksymalnie zbliżony do uzyskanego z pomiarów. (Metody pomiaru i konstrukcja obrazu metodą zbiorów poziomicowych w tomografii impedancyjnej). Keywords: Electrical Impedance Tomography, Finite Element Method, Inverse Problem, Level Set Method Słowa kluczowe: tomografia impedancyjna, metoda elementów skończonych, zagadnienie odwrotne, metoda zbiorów poziomicowych Introduction Electrical impedance tomography is a widely investigated problem with many applications in physical and biological sciences. It is well known that the inverse problem is nonlinear and highly ill-posed. The objection function is minimized (the difference between the potential due to the applied current and the measured potential). The conductivity values in different regions are determined by the finite element method [1]. The representation of the boundary shape and its evolution during an iterative reconstruction process is achieved by the level set method [2,9,11]. Given the boundary,[...]

Variational level set method for minimizing the functional in EIT

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A method based on the variational level set algorithm and the Mumford-Shah algorithm to solve the inverse problem in the electrical impedance tomography was proposed. In addition to minimizing the objection function of the difference between the potential due to the applied current and the measured potential. The conductivity values in different regions are determined by the finite element method. The representation of the shape of the boundary and its evolution during an iterative reconstruction process is achieved by the level set method. Streszczenie. W pracy przedstawiono metodę rozwiązania zagadnienia odwrotnego w tomografii impedancyjnej opartą na idei zbiorów poziomicowych z wykorzystaniem metody Mumford-Shaha. Algorytm numeryczny rozwiązania jest odpowiednią kombinacją wariacy[...]

Various kinds of level set applications in electrical impedance tomography

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This paper presents the applications of the level set function for identification the unknown shape of an interface motivated by Electrical Impedance Tomography (EIT) by using a several level set algorithms. The conductivity values in different regions are determined by the finite element method. The applications were based on the level set method, the variational level set algorithm and the Mumford-Shah algorithm to solve the inverse problem. Streszczenie. W pracy przedstawiono metodę rozwiązania zagadnienia odwrotnego w tomografii impedancyjnej opartą na idei zbiorów poziomicowych, wariacyjnej metodzie zbiorów poziomicowych oraz modelu Mumforda-Shaha. Algorytmy numeryczne rozwiązania są odpowiednią kombinacją wymienionych metod oraz metody elementów skończonych. (Typy aplikacji zbiorów poziomicowych w tomografii impedancyjnej). Keywords: Variational Level Set Method, Mumford-Shah model, Electrical Impedance Tomography, Finite Element Method Słowa kluczowe: wariacyjna metoda zbiorów poziomicowych, tomografia impedancyjna, metoda elementów skończonych Introduction In this paper there were proposed algorithms based on the level set function [6,7,8,9], Mumford-Shah model [5,10,11] and the variational level set method [4] to solve the inverse problem in the electrical impedance tomography (fig.1). The conductivity values in different regions are determined by the finite element method [2]. Numerical iterative algorithm is a combination of the level set methods for the evolving step edges and the finite element method for computing the velocity. The objective function is defined as the difference between the potential due to the applied current and the measured potential [1,2,3]. This function is minimized. Fig. 1. The reconstruction methods Level set methods The idea, as devised in 1987 by S. Osher and J.A. Sethian is merely to define a smooth function (x,t) , that represents the interface as the set where (x,t) ɧ[...]

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