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Wyświetlanie 1-10 z 503
Tytuł:
Comparing methods of image reconstruction in electrical impedance tomography
Autorzy:
Rymarczyk, T.
Filipowicz, S.F.
Sikora, J.
Powiązania:
https://bibliotekanauki.pl/articles/97630.pdf
Data publikacji:
2011
Wydawca:
Politechnika Poznańska. Wydawnictwo Politechniki Poznańskiej
Tematy:
impedance tomography
electrical impedance tomography
EIT
Opis:
The problem of the image reconstruction in Electrical Impedance Tomography (EIT) is a highly ill-posed inverse problem. There are mainly two categories of image reconstruction algorithms, the direct algorithm and the iterative algorithm which was used in this publication. 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.
Źródło:
Computer Applications in Electrical Engineering; 2011, 9; 23-33
1508-4248
Pojawia się w:
Computer Applications in Electrical Engineering
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Analysis for Improvement of Doppler Tomography Imaging of Objects Scattering Continuous Ultrasonic Waves
Autorzy:
Świetlik, Tomasz
Opieliński, Krzysztof J.
Powiązania:
https://bibliotekanauki.pl/articles/176449.pdf
Data publikacji:
2020
Wydawca:
Polska Akademia Nauk. Czasopisma i Monografie PAN
Tematy:
continuous wave ultrasonic tomography
Doppler tomography
image reconstruction
Opis:
The paper describes an innovative ultrasound imaging method called Doppler Tomography (DT), otherwise known as Continuous Wave Ultrasonic Tomography (CWUT). Thanks to this method, it is possible to image the tissue cross-section in vivo using a simple two-transducer ultrasonic probe and using the Doppler effect. It should be noted that DT significantly differs from the conventional ultrasound Doppler method of measuring blood flow velocity. The main difference is that when measuring blood flow, we receive information with an image of the velocity distribution in a given blood vessel (Nowicki, 1995), while DT allows us to obtain a cross-sectional image of stationary tissue structure. In the conventional method, the probe remains stationary, while in the DT method, the probe moves and the examined tissue remains stationary. This paper presents a method of image reconstruction using the DT method. First, the basic principle of correlation of generated Doppler frequencies with the location of inclusions from which they originate is explained. Then the exact process and algorithm in this method are presented. Finally, the impact of several key parameters on imaging quality is examined. As a result, the conclusions of the research allow to improve the image reconstruction process using the DT method.
Źródło:
Archives of Acoustics; 2020, 45, 2; 329-339
0137-5075
Pojawia się w:
Archives of Acoustics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Badania wpływu niedokładności równoległych torów pomiarowych na dokładność rekonstrukcji przewodności w tomografii elektrycznej
Uncertainty influence investigation of the measurement parallel channels on the reconstruction conductivity accuracy in electrical tomography
Autorzy:
Dorozhovets, M.
Prygrodsky, A.
Brydak, K.
Powiązania:
https://bibliotekanauki.pl/articles/155984.pdf
Data publikacji:
2011
Wydawca:
Stowarzyszenie Inżynierów i Techników Mechaników Polskich
Tematy:
tomografia impedancyjna
electrical tomography
Opis:
W pracy przedstawiono analizę wpływu oddziaływań addytywnych oraz multiplikatywnych w torze pomiaru napięć międzyelektrodowych na dokładność rekonstrukcji rozkładu przestrzennego przewodności w tomografii elektrycznej (TE). Przedstawiono ogólną zasadę konstruowania obrazu TE, metodę pomiarową realizującą równoległy pomiar napięć międzyelektrodowych oraz algorytm rekonstrukcji obrazu przewodności.
The influence analysis of additive and multiplicative interactions in measuring system of inter-electrode voltages on accuracy of reconstruction of conductivity spatial distribution in electrical tomography has been presented in this paper. The measurement method based on parallel controlling of interelectrode voltages was considered. It was referred to analogical research based on serial measurement method [3]. The errors of measuring apparatus were presented as sum of three basic components: random additive, systematic additive and systematic multiplicative. For quantitative comparison of particular errors influence on reconstruction errors the conversion factor was introduced. It was defined as square root of ratio of reconstruction variance errors. The results of investigations of conversion degree of instrumental errors in relation to errors of conductivity image obtained from relations (6) and (7) as well as using Mote Carlo method have been compared (Fig.1). The instrumental errors have bigger negative influence on reconstruction accuracy of elements conductivity in the internal area of considered object (lower numbers in figures). They are cause of results' retrogradation in this area. The influence of systematic additives and random errors is significantly bigger than systematic multiplicative. The derived relations can be applied for the requirement formulation in relation to accuracy requirements of measuring systems on the beginning of tomography system design process.
Źródło:
Pomiary Automatyka Kontrola; 2011, R. 57, nr 12, 12; 1552-1554
0032-4140
Pojawia się w:
Pomiary Automatyka Kontrola
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
STEM-EDX and FIB-SEM Tomography of ALLVAC 718Plus Superalloy
Autorzy:
Kruk, A.
Cempura, G.
Lech, S.
Czyrska-Filemonowicz, A.
Powiązania:
https://bibliotekanauki.pl/articles/354670.pdf
Data publikacji:
2016
Wydawca:
Polska Akademia Nauk. Czytelnia Czasopism PAN
Tematy:
TEM
SEM
STEM-EDX tomography
FIB-SEM tomography
Allvac 718Plus
Opis:
Allvac 718Plus (718Plus) is a high strength, corrosion resistant nickel- based superalloy used for application in power generation, aeronautics and aerospace industry. The 718Plus microstructure consists of a γ matrix with γ’-Ni3(Al,Ti) and some δ- Ni3Nb phases as well as lamellar particles (η-Ni3Ti, η*-Ni6AlNb or Ni6(Al,Ti)Nb) precipitated at the grain boundaries. The primary strengthening mechanism for this alloy is a precipitation hardening, therefore size and distribution of precipitates are critical for the performance of the alloy. The aim of this study was to characterize precipitates in the 718Plus superalloy using Scanning Transmission Electron Microscope combined with Energy Dispersive X-ray Spectroscopy (STEM-EDX) and Focused Ion Beam Scanning Electron Microscope (FIB-SEM). The STEM-EDX and FIB-SEM tomography techniques were used for 3D imaging and metrology of the precipitates. Transmission electron microscopy and EDX spectroscopy were used to reveal details of the 718Plus microstructure and allow determine chemical composition of the phases. The study showed that electron tomography techniques permit to obtain complementary information about microstructural features (precipitates size, shape and their 3D distribution) in the reconstructed volume with comparison to conventional particle analysis methods, e.g. quantitative TEM and SEM metallography.
Źródło:
Archives of Metallurgy and Materials; 2016, 61, 2A; 535-542
1733-3490
Pojawia się w:
Archives of Metallurgy and Materials
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
PET and SPECT imaging as a solid guide to detect and discriminate atypical phenotypes of neurodegenerative disorders
Autorzy:
Ruffini, Livia
Zilioli, Alessandro
Cervati, Veronica
Lauretani, Fulvio
Misirocchi, Francesco
Maggio, Marcello
Migliari, Silvia
Graziani, Tiziano
Cidda, Carla
Baldari, Giorgio
Spallazzi, Marco
Scarlattei, Maura
Powiązania:
https://bibliotekanauki.pl/articles/40521373.pdf
Data publikacji:
2024-03-30
Wydawca:
Uniwersytet Rzeszowski. Wydawnictwo Uniwersytetu Rzeszowskiego
Tematy:
atypical phenotypes
neurodegenerative diseases
positron emission tomography
single photon emission computed tomography
Opis:
Introduction and aim. Atypical or mixed presentations of neurodegenerative disorders may postpone or confound the final diagnosis. Molecular imaging with positron emission tomography (PET) and single photon emission computed tomography (SPECT) radioligands provide target-specific information and may anticipate the diagnosis by “in vivo” detection of the neuropathological substrate, as Aβ deposition, nigrostriatal dopaminergic depletion or tau inclusions. This concise review will discuss the potential of PET and SPECT imaging as a solid guide to better characterize atypical phenotypes of neurodegeneration in the clinical routine, with the potential to drive personalized interventions, improve cohort uniformity for clinical trials, and serve as biomarkers for targeted molecular therapies. Material and methods. Literature search was performed focusing on the role of PET and SPECT imaging in assessing atypical phenotypes of neurodegeneration, using the electronic source of database PubMed/MEDLINE and the web-based search engines Google, Google Scholar. Analysis of the literature. New disease-modifying drugs may increase their effect with early initiation, which is especially important in working persons and younger subjects presenting atypical symptoms. In older individuals, the coexistence of neurodegeneration, age-related changes, cerebrovascular lesions, or depression makes challenging a definitive diagnosis. Quantitative tools able to measure tracer distribution increase the accuracy of molecular neuroimaging creating topographic maps that compare subject’s data with healthy controls databases. Conclusion. Atypical phenotypes may be associated with quantitative key-pattern allowing a more precise and early diagnosis of the neurodegenerative disorder. Finally, quantitative assessment of the pathological substrates allows us to track the disease process and measure treatment response.
Źródło:
European Journal of Clinical and Experimental Medicine; 2024, 22, 1; 201-221
2544-2406
2544-1361
Pojawia się w:
European Journal of Clinical and Experimental Medicine
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Szybka metoda rozwiązania zagadnienia odwrotnego tomografii elektrycznej
Fast method of electrical tomogfaphy inverse problem solution
Autorzy:
Brydak, K.
Dorozhovets, M.
Powiązania:
https://bibliotekanauki.pl/articles/152574.pdf
Data publikacji:
2007
Wydawca:
Stowarzyszenie Inżynierów i Techników Mechaników Polskich
Tematy:
tomografia elektryczna
electrical tomography
Opis:
W pracy przedstawiono podstawowe problemy rekonstrukcji obrazu rozkładu przestrzennego parametrów elektrycznych w tomografii elektrycznej. Zaproponowano szybszą i bardziesz precyzyjną metodę obliczania macierzy Jacobiego bez błędu metody. Zaproponowano metodę adaptacji parametru regularyzacji w procesie rozwiązania zagadnienia odwrotnego, dzięki czemu znacznie poprawia się zbieżność algorytmu rekonstrukcji. Zaprezentowano wyniki eksperymentów numerycznych dla kilku wybranych modeli rozkładu przestrzennego parametrów.
This article investigates basic problems concerning image reconstruction of electrical parameters space distribution in electrical tomography. The fast and precise metod (without methodical error) or the Jakobian matrix calculation is proposed. Moreover, the algorithm of regularized parameter adaptation in inverse problem solution is proposed. As a result of this, time of the image reconstruction is significant reduced and image becomes more precise. On top of thatm the article presents the results of some numerical experiments for the selected object spatial distribution parameter models.
Źródło:
Pomiary Automatyka Kontrola; 2007, R. 53, nr 9 bis, 9 bis; 425-428
0032-4140
Pojawia się w:
Pomiary Automatyka Kontrola
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Multi phase flow measurements with the application of ECT/ERT DECART multimodality tomograph
Pomiary przepływów wielofazowych z wykorzystaniem tomografu multimodalnego DECART
Autorzy:
Nowakowski, J.
Banasiak, R.
Wajman, R.
Sankowski, D.
Powiązania:
https://bibliotekanauki.pl/articles/408319.pdf
Data publikacji:
2017
Wydawca:
Politechnika Lubelska. Wydawnictwo Politechniki Lubelskiej
Tematy:
tomography
electrical capacitance tomography
gamma ray
tomografia
elektryczna tomografia pojemnościowa
promieniowanie gamma
Opis:
The multi-phase flow measurements are very important tasks in many areas of industrial processes applications. One of them is undersea exploration of oil in the petroleum industry. The submitted paper presents application of DECART tomograph designed and built in Lodz University of Technology - together with combined measurements of signals acquired from gamma ray measurement system. Use of all measuring modalities allowed for performing measurements of a flow composed of sea water, oil and gas. The paper presents theoretical principles applied to design multimodality tomograph and results of experiments performed in the University of Bergen. Measurement confirmed that multi-modality approach allows giving fast and reliable on-line results of measurements of composition of multi-phase flow. Applied algorithms allowed to speed up on-line measurements and presenting results in a form required in industrial applications. The derived conclusions can be used as guidelines for preparation of industrial applicable construction of tomograph.
Pomiary przepływów wielofazowych są szeroko wykorzystywane w wielu procesach przemysłowych. Jednym z nich jest przemysł petrochemiczny, w szczególności dziedzina eksploatacji podwodnych złóż ropy naftowej. W artykule zostało przedstawione zastosowanie tomografu DECART - zaprojektowanego i zbudowanego w Instytucie Informatyki Stosowanej Politechniki Łódzkiej. Pomiary z tomografu zostały powiązane z sygnałami uzyskanymi z systemu pomiaru promieniowania gamma. Wykorzystanie danych uzyskanych z różnych rodzajów czujników umożliwiło pomiar przepływu mieszaniny składającej się z wody morskiej, ropy naftowej i gazu. W pracy przedstawiono podstawy teoretyczne, które stanowiły punkt wyjścia do wykorzystania tomografu multimodalnego jak i wyniki eksperymentów przeprowadzonych na Uniwersytecie w Bergen. Pomiary potwierdziły, że podejście multimodalne umożliwia szybki i niezawodny pomiar udziału faz w przepływie wielofazowym. Zastosowane algorytmy pozwalają na przyspieszenie pomiarów on-line i przedstawienie wyników w formie wymaganej w zastosowaniach przemysłowych. Wnioski z badań mogą być wykorzystane jako wskazówki dla konstrukcji tomografu do praktycznych zastosowań przemysłowych.
Źródło:
Informatyka, Automatyka, Pomiary w Gospodarce i Ochronie Środowiska; 2017, 7, 1; 46-49
2083-0157
2391-6761
Pojawia się w:
Informatyka, Automatyka, Pomiary w Gospodarce i Ochronie Środowiska
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Monitoring of combustion processes in industrial burners using electrical capacitance tomography
Autorzy:
Gut, Z.
Wolanski, P.
Oleszczak, P.
Powiązania:
https://bibliotekanauki.pl/articles/245557.pdf
Data publikacji:
2011
Wydawca:
Instytut Techniczny Wojsk Lotniczych
Tematy:
combustion
industrial burner
diagnostic
tomography
Opis:
The development of diagnostic methods suitable for the monitoring of practical flames is an important objective, which is receiving a growing attention and significant research efforts. This is motivated by the need to achieve a more precise description of the process and, ultimately, implement efficient and reliable control and optimization methods as a key step towards the development of more efficient, flexible, reliable and clean combustion systems. Many interesting attempts have been proposed, involving very different approaches in the use of various instruments and sensors. One of parameter difficult to control is distribution of reaction zone. Presently, such system which allows monitoring combustion process of industrial burners does not exist. Measurements of temperature or control of exist flame by using ionization probe provide only partial information about performance of combustion process. For that reason, new diagnostic methods should be developed. Many and interesting attempts have been proposed but one of interesting solution will be development of combustion process diagnostic methods by means of the Electrical Capacitance Tomography (ECT). Obtained results show that it will be a very good tool for research proposes, especially in development of a new combustion chamber operated at very high pressure, where installation of optical windows is very difficult and many time not possible.
Źródło:
Journal of KONES; 2011, 18, 3; 117-121
1231-4005
2354-0133
Pojawia się w:
Journal of KONES
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Acoustic tomography of a turbulent water jet
Autorzy:
Gavrilenko, V.
Didenkulov, I.
Kustov, L.
Martyanov, A.
Nechayeva, M.
Vyugin, P.
Pronchatov-Rubtsov, N.
Powiązania:
https://bibliotekanauki.pl/articles/331748.pdf
Data publikacji:
2003
Wydawca:
Polskie Towarzystwo Akustyczne
Tematy:
acoustic tomography
turbulent water
hydroacoustics
Opis:
Measurement of parameters of flowing liquid is one of problems, which have many applications. in the present paper we describe linear and nonlinear acoustic tomography methods for reconstruction of parameters of a turbulent water jet with gas bubbles. Experiments on both techniques are described. in the linear acoustic method it was measured fluctuations of acoustic signal passed through the jet. In the nonlinear acoustic technique it was measured spectra of combination scattering signals in the jet. Experiments were done in a water tank with a submerged water jet. The results of the work demonstrate the possibility of the tomography of flowing bubble liquids.
Źródło:
Hydroacoustics; 2003, 6; 91-100
1642-1817
Pojawia się w:
Hydroacoustics
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Fibromuscular dysplasia – a case description
Autorzy:
Leksa, Natalia
Seweryn, Bartosz
Uberman-Kluz, Dominika
Galiniak, Sabina
Kawalec, Magdalena
Powiązania:
https://bibliotekanauki.pl/articles/454927.pdf
Data publikacji:
2018
Wydawca:
Uniwersytet Rzeszowski. Wydawnictwo Uniwersytetu Rzeszowskiego
Tematy:
fibromuscular dysplasia
arteries
computed tomography
Opis:
Introduction. Fibromuscular dysplasia is an idiopathic, non-inflammatory and non-atherosclerotic disease that affects the walls of arteries (mostly renal and carotid arteries). Histological classification distinguishes three main types of the disease, depending on the structural changes occurring in one of the three layers of arterial vessel walls. Objective. We present here a case of fibromuscular dysplasia affecting the internal carotid arteries. Case description. This article describes the case of a 52-year-old female patient with hypertension, hyperlipidemia, and a cardiac pacemaker in whom computed tomography angiography revealed a narrowing of the internal carotid arteries without atherosclerotic symptoms. We describe the diagnostic methods and various types of treatment that the patient suffering from fibromuscular dysplasia was subjected to. Conclusions. Due to a low detection rate of fibromuscular dysplasia, if the disease is suspected, all available diagnostic methods should be employed. Taking into account the unknown etiology of the disease, it is not possible to use a preventive therapy, or a therapy focused on stalling the progression of the disease
Źródło:
European Journal of Clinical and Experimental Medicine; 2018, 1; 63-67
2544-2406
2544-1361
Pojawia się w:
European Journal of Clinical and Experimental Medicine
Dostawca treści:
Biblioteka Nauki
Artykuł
Wyświetlanie 1-10 z 503

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