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1
Content available remote Thermoacoustic imaging of human finger joints and bones
100%
Lin H. , Weizhi Q. , Yuan Z. , Zihui C. , Nengzhu Z. , Jian R. , Dakun L.
X-Acoustics: Imaging and Sensing
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2014
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tom 1
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nr 1
EN
In this study, we explore a new application of thermoacoustic tomography (TAT) for imaging human finger joints and bones. Three volunteers’ finger joints and bones were visualized with satisfying image contrast and spatial resolution by a TAT scanner. The recovered TAT images revealed apparent microwave absorption differences between the joint cavity and bone. Beyond the full single finger imaging, a volunteer’s four fingers were clearly and concurrently imaged. To confirm our observations, MRI images of two volunteers’ fingers were performed, and the TAT recovered shape/size of the fingers were consistent with the MRI findings. To further assess the feasibility of TAT for finger joint and bone imaging, we quantitatively calculated the conductivity of a case. This initial study suggests that TAT may be a good candidate for screening, diagnosing, and monitoring treatment of joint and bone diseases.
2
Cross-hole tomography using simulated annealing technique
100%
Sircar A. , Chouhan R. K. S.
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1998
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tom Vol. 46, nr 2
161-170
EN
We describe a method of nonlinear inversion of travel-time tomography data based on a global optimisation method called Simulated Annealing (SA). The simulated annealing has recently been found to be computationally efficient in several geophysical parameter estimation problems. The solution is independent of the initial model because local minima are avoided during the process by convenient up-hill down-hill exploration of the model space. Preliminary results using synthetic model show how a moderately complex structure can be obtained by SA.
3
Content available remote Improved and isotropic resolution in tomographic diffractive microscopy combining sample and illumination rotation
100%
Vertu S. , Flügge J. , Delaunay J.-J. , Haeberlé O.
Open Physics
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2011
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tom 9
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nr 4
969-974
EN
Tomographic Diffractive Microscopy is a technique, which permits to image transparent living specimens in three dimensions without staining. It is commonly implemented in two configurations, by either rotating the sample illumination keeping the specimen fixed, or by rotating the sample using a fixed illumination. Under the first-order Born approximation, the volume of the frequency domain that can be mapped with the rotating illumination method has the shape of a “doughnut”, which exhibits a so-called “missing cone” of non-captured frequencies, responsible for the strong resolution anisotropy characteristic of transmission microscopes. When rotating the sample, the resolution is almost isotropic, but the set of captured frequencies still exhibits a missing part, the shape of which resembles that of an apple core. Furthermore, its maximal extension is reduced compared to tomography with rotating illumination. We propose various configurations for tomographic diffractive microscopy, which combine both approaches, and aim at obtaining a high and isotropic resolution. We illustrate with simulations the expected imaging performances of these configurations.
4
Content available remote Diffraction microtomography with sample rotation: influence of a missing apple core in the recorded frequency space
100%
Vertu S. , Delaunay J.-J. , Yamada I. , Haeberlé O.
Open Physics
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2009
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tom 7
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nr 1
22-31
EN
Diffraction microtomography in coherent light is foreseen as a promising technique to image transparent living samples in three dimensions without staining. Contrary to conventional microscopy with incoherent light, which gives morphological information only, diffraction microtomography makes it possible to obtain the complex optical refractive index of the observed sample by mapping a three-dimensional support in the spatial frequency domain. The technique can be implemented in two configurations, namely, by varying the sample illumination with a fixed sample or by rotating the sample using a fixed illumination. In the literature, only the former method was described in detail. In this report, we precisely derive the three-dimensional frequency support that can be mapped by the sample rotation configuration. We found that, within the first-order Born approximation, the volume of the frequency domain that can be mapped exhibits a missing part, the shape of which resembles that of an apple core. The projection of the diffracted waves in the frequency space onto the set of sphere caps covered by the sample rotation does not allow for a complete mapping of the frequency along the axis of rotation due to the finite radius of the sphere caps. We present simulations of the effects of this missing information on the reconstruction of ideal objects.
5
Content available remote A simple smoothed velocity model of the uppermost Earth’s crust derived from joint inversion of Pg and Sg waves
88%
Holub K. , Ruzek B. , Rusajova J.
Acta Geophysica
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2012
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tom Vol. 60, no. 2
487-497
EN
The paper presents some results of seismic experiments carried out on the territory of northern Moravia and Silesia, roughly delimited by the coordinates 16°E-19°E and 49°N-51°N. The experiments were aimed at compiling a velocity model of the uppermost Earth's crust using the database of arrival times of Pg and Sg waves recorded at a fairly large number of seismic stations, which enabled us to produce a simple 1D-layered velocity model of the region. The velocity model was computed using the traditional tomographic iterative process composed of consecutive solutions of linear equations. Based on the analysis of velocity distribution, it was found that the velocities of Pg and Sg waves increase from about 5.9 and 3.3 km/s at the surface, to about 6.1 and 3.5 km/s at a depth of 11 km, respectively.
6
Content available Three-dimensional modelling of the crustal structure in the contact zone between Antarctic Peninsula and South Pacific from seismic data
88%
Środa P. , Środa P.
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nr 2
7
Content available remote Essence (siła napędowa) oraz AmbientExperience (idealna aranżacja pracowni) w tomografii komputerowej PHILIPS
75%
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2007
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tom Vol. 13, nr 4
354-354
PL
Głównym źródłem inspiracji i bazą podstawowych założeń dla firmy PHILIPS na etapie projektowania nowych urządzeń medycznych jest z jednej strony znajomość anatomii człowieka, a z drugiej - ocena aktualnych potrzeb i oczekiwań służby zdrowia na całym świecie.
8
Nowa konstrukcja tomografu pojemnościowego do kontroli przepływów dwufazowych
75%
Zaprawa P.
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2010
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tom Vol. 51, nr 2
14-16
PL
W pracy przedstawiono nową koncepcję budowy układu tomografu pojemnościowego dla aplikacji przemysłowych. Zaproponowano nową strukturę układu pomiarowego oraz przedstawiono przykładowe wyniki. Przedstawiono zastosowany algorytm oraz wyniki rekonstrukcji obrazu otrzymane na podstawie opracowanego oprogramowania.
EN
New construction ideas of capacitance tomography for industrial applications are presented in this paper. New hardware structure of measurement circuit are proposed with experimental results as proof. Additionally author present image reconstruction results with applied algorithm.
9
Content available remote Silo emptying in aspect of the non-desctructive detection methods application
75%
Niedostatkiewicz M. , Chaniecki Z. , Sankowski D.
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2009
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tom z. 114
155-159
EN
The paper presents results of concentration measurements in non-cohesive sand during free flow in rectangular and cylindrical silos using different non-invasive methods like thermography, X-ray photography, X-ray tomography and electrical capacitance tomography. The effect of the initial bulk solid density and roughness of silo walls on the concentration changes were investigated. Advantages and disadvantages of all presented methods were outlined. The possibility of application of the Electrical Capacitance Tomography (ECT) for observation the porosity changes of the bulk solid was pointed out.
10
Content available remote Limits of the weakly coupled field assumption for low conductivity electromagnetic induction tomography
75%
Yin W. , Peyton A. J. , Zysko G. , Dekdouk B.
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2009
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tom z. 114
75-79
EN
In medical or low conductivity electromagnetic induction tomography, a low frequency approximation (i.e. neglecting the diffusion effect) can significantly simplify the forward and inverse solutions. However, this approximation normally leads to the over prediction of the amount of eddy currents induced by the transmitter coil, and hence to an overestimation of the secondary voltage measured on the receiver coil. The reason is because the penetration of the field into the object is not correctly described and the skin effect is ignored. In effect, the theory assumes that the signal is coming from a larger-than-actual volume. This paper uses an exact analytical solution for a coil(s) near a stratified media derived from a full wave theory to evaluate the skin effect at a range of frequencies and compares it with a simple model which omits the skin effect. The error due to the approximation is evaluated and the highest frequency at which the approximation holds valid to within a defined error range is ascertained.
11
Tomography control of the workflow of pulverized coal used in electrical power generation
75%
Polakowski K. , Filipowicz S. F. , Sikora J.
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2010
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tom No. 61
157-165
EN
The simplification of calculations with assuring the sufficient accuracy in making tomography images of analyzed physical phenomenon should succeed in faster obtaining of results. This issue is important because the contemporary tomography is expected to bring real time, tomography images of dynamically changing environment. Taking into consideration growing ecology and safety demands, there is a need for more accurate and cheaper ways to monitor workflows of gases, vapors, fluids and biphasic mixtures, in power generation boilers.
12
Modelowanie zmian osteoporotycznych z wykorzystaniem obrazów z tomografii komputerowej
63%
John A. , Wysota P.
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2008
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tom T. 5, nr 36
151-158
PL
W pracy poruszono tematykę modelowania zmian chorobowych spowodowanych przez osteoporozę i zbadania relacji między tymi zmianami a stanem naprężenia i odkształcenia kości miednicy człowieka (co ma wpływ na jej funkcjonowania w układzie kostnym człowieka). Skupiono się głównie na zmianach własności fizycznych tkanki kostnej. Przedstawiono etapy przetwarzania danych tomograficznych w celu uzyskania informacji o geometrii oraz własnościach materiałowych kości. Zastosowana metoda umożliwia wykorzystanie QCT do budowy modelu numerycznego kości miednicy człowieka. Stan wytężenia kości analizowano na podstawie rezultatów otrzymanych z symulacji numerycznych.
EN
osteoporosis on functioning in bone system. The osteoporotic changes concentrated on the changes of material properties of bone. The conversion from images of computed tomography to material properties of bone is presented. The date from QCT made possible to creation the numerical model of analyzed structure. Osteoporotic changes were considered as establishing material properties estimated on the base QCT. The effort of pelvic bone is analyzed on the base obtained results.
13
Tomografia rentgenowska w diagnostyce syntetycznych koszy łożysk tocznych
51%
Zborowski A.
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2013
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tom nr 2
132-139
PL
W artykule przedstawiono zastosowanie tomografii rentgenowskiej w diagnostyce syntetycznych elementów konstrukcyjnych łożysk tocznych. Metodę zastosowano do wykrywania wewnętrznych wad materiałowych koszyków łożyskowych wykonanych z tworzywa sztucznego. Zaprezentowano przykłady wad występujących w obiektach wykonanych z dwóch różnych materiałów konstrukcyjnych. Udokumentowano wpływ konstrukcji narzędzia formującego na występowanie, rozmiar oraz rozmieszczenie wad wewnętrznych w postaci pustek i pęcherzy powietrza. Przeprowadzone badania potwierdzają wysoką przydatność metody komputerowej tomografii rentgenowskiej w diagnostyce wewnętrznej makrostruktury obiektów wykonanych z tworzyw sztucznych. Zastosowane instrumentarium badawcze umożliwiło precyzyjną ocenę ilościową i objętościową wad struktury materiałowej w postaci pęcherzy powietrza i pustek występujących w syntetycznych koszykach łożyskowych wykonanych z PA oraz POM. Tomografia komputerowa pozwoliła na zbadanie struktury materiału pod względem geometrycznym. Wykryto nieciągłości materiału oraz przeprowadzono ocenę porowatości. Wykonane badania wykazały istotny wpływ rozwiązań konstrukcyjnych systemu formującego na jakość struktury wewnętrznej wyrobu gotowego. Uzyskane rezultaty badań dokumentują bezpośrednią zależność wad struktury wewnętrznej od skuteczności odpowietrzania gniazda formującego.
EN
Presented is the application of X-ray tomography in diagnostics of the synthetic construction elements of roller bearings. This method was applied for detection of inner material faults of bearing cages made of a synthetic. Presented are examples of faults occurring in objects made of two different construction materials. Documented was the impact of a forming tool construction on occurrence, size and location of internal faults in the form of voids and air bubbles. The carried out research confirms the great usefulness of the computer X-ray tomography method in diagnostics of the internal macrostructure of objects made of synthetics. The applied research instrumentarium enabled precise quantity and quality assessment of material structure faults in the form of air bubbles and voids occurring in synthetic bearing cages made of PA and POM. The computer tomography allowed testing of the material in relation to its geometric structure. Detected were material discontinuities and porosity assessment was made. The made tests showed important influence of the forming system construction solutions on the quality of a ready product internal structure. The received results document the direct dependence of internal structure faults from the effectiveness of mould cavity venting.
14
Content available remote Mikro- i nanoanaliza materiałów przy pomocy technik EELS, EFTEM oraz tomografii w wysokorozdzielczym mikroskopie s/tem - podstawy, wymagania, przegląd literatury i przygotowanie do wdrożenia w IMŻ
51%
Arabasz S. , Wojtas J. , Maciosowski A. , Wiedermann J.
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2010
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tom T. 62, nr 4
72-75
PL
W pracy rozpoznano możliwości badawcze nowych technik transmisyjnej mikroskopii elektronowej opartych o filtrację energii elektronów przechodzących przez próbkę - spektroskopii strat energii EELS oraz obrazowania EFTEM. Zwrócono szczególną uwagę na ich zastosowanie do analizy struktury i składu chemicznego próbek stalowych, na przygotowanie próbek oraz na dobór odpowiednich parametrów pracy mikroskopu dla tych technik.
EN
In this work, the research capabilities of the new transmission electron microscope techniques based on energy filtration of electrons transmitted through the sample, i.e. electron energy loss spectroscopy (EELS) and energy-filtered transmission electron microscopy (EFTEM) imaging, were identified. Particular attention was paid to their application in analysis of structure and chemical composition of steel samples and to sample preparation and selection of microscope operating parameters suitable for these techniques.
15
Content available remote Informationally incomplete quantum tomography
51%
Teo Y. S. , Řeháček J. , Hradil Z.
Quantum Measurements and Quantum Metrology
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2013
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tom 1
57-83
EN
In quantum-state tomography on sources with quantum degrees of freedom of large Hilbert spaces, inference of quantum states of light for instance, a complete characterization of the quantum states for these sources is often not feasible owing to limited resources. As such, the concepts of informationally incomplete state estimation becomes important. These concepts are ideal for applications to quantum channel/ process tomography, which typically requires a much larger number of measurement settings for a full characterization of a quantum channel. Some key aspects of both quantumstate and quantum-process tomography are arranged together in the form of a tutorial review article that is catered to students and researchers who are new to the field of quantum tomography, with focus on maximum-likelihood related techniques as instructive examples to illustrate these ideas.
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