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206 results on '"Chukalina M"'

2. Segmentation Criteria in the Problem of Porosity Determination based on CT Scans

Author

Kokhan, V., Grigoriev, M., Buzmakov, A., Uvarov, V., Ingacheva, A., Shvets, E., and Chukalina, M.

Subjects
Computer Science - Computer Vision and Pattern Recognition
Abstract

Porous materials are widely used in different applications, in particular they are used to create various filters. Their quality depends on parameters that characterize the internal structure such as porosity, permeability and so on. Computed tomography (CT) allows one to see the internal structure of a porous object without destroying it. The result of tomography is a gray image. To evaluate the desired parameters, the image should be segmented. Traditional intensity threshold approaches did not reliably produce correct results due to limitations with CT images quality. Errors in the evaluation of characteristics of porous materials based on segmented images can lead to the incorrect estimation of their quality and consequently to the impossibility of exploitation, financial losses and even to accidents. It is difficult to perform correctly segmentation due to the strong difference in voxel intensities of the reconstructed object and the presence of noise. Image filtering as a preprocessing procedure is used to improve the quality of segmentation. Nevertheless, there is a problem of choosing an optimal filter. In this work, a method for selecting an optimal filter based on attributive indicator of porous objects (should be free from 'levitating stones' inside of pores) is proposed. In this paper, we use real data where beam hardening artifacts are removed, which allows us to focus on the noise reduction process, Comment: ICMV 2019, 8 pages, 5 figures

Published
2019

8. Asymmetry with respect to the magnetic field direction in the interaction between the quantum states of two coupled superconducting rings

Author

Kuznetsov, V. I., Firsov, A. A., Dubonos, S. V., and Chukalina, M. V.

Subjects
Condensed Matter - Superconductivity, Condensed Matter - Mesoscale and Nanoscale Physics
Abstract

The interaction between the quantum states of two aluminum superconducting rings forming an 8-shape circular-asymmetric microstructure was examined under a threading magnetic flux and bias by an alternating current without a dc component. Quantum oscillations of the rectified dc voltage Vdc(B) as a function of magnetic field were measured in the 8-shape microstructure at various bias ac currents and temperatures close to critical. Fourier and wavelet analyses of Vdc(B) functions revealed the presence of various combination frequencies in addition to two ring fundamental frequencies, which suggests the interaction in the structure. Deviation of the Vdc(B) function from oddness with respect to the magnetic field direction was found for the first time., Comment: author english version, 3 pages, 3 figires, Proc. of the XXXIV Conference on Low-Temperature Physics "NT-34" (Russia, 2006)

Published
2007
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9. Excited two-dimensional magnetopolaron states in quantum well of resonant tunnel junction

Author

Ivanov, D. Yu., Chukalina, M. V., Takhtamirov, E. G., Dubrovskii, Yu. V., Eaves, L., Volkov, V. A., Vdovin, E. E., Portal, J. -C., Maude, D. K., Henini, M., and Hill, G.

Subjects
Condensed Matter - Mesoscale and Nanoscale Physics, Condensed Matter - Disordered Systems and Neural Networks
Abstract

Tunnel spectroscopy is used to probe the electronic structure in GaAs quantum well of resonant tunnel junction over wide range of energies and magnetic fields normal to layers. Spin degenerated high Landau levels ($N=2\div7$) are found to be drastically renormalised near energies when the longitudinal optical-phonon ($\hbar\omega_{LO}$) and cyclotron energy ($\hbar\omega_{C}$) are satisfied condition $\hbar\omega_{LO}=m\hbar\omega_{C}$, where $m=1,2,3$. This renormalisation is attributed to formation of resonant magnetopolarons, i.e. mixing of high index Landau levels by strong interaction of electrons at Landau level states with LO-phonons., Comment: 4 pages, 3 eps figures, revtex4

Published
2005

13. High resolution 3D visualization of the spinal cord in a post-mortem murine model

Author

Bukreeva, I, Asadchikov, V, Buzmakov, A, Chukalina, M, Ingacheva, A, Korolev, N, Bravin, A, Mittone, A, Biella, G, Sierra, A, Brun, F, Massimi, L, Fratini, M, Cedola, A, Bukreeva I, Asadchikov V, Buzmakov A, Chukalina M, Ingacheva A, Korolev NA, Bravin A, Mittone A, Biella GEM, Sierra A, Brun F, Massimi L, Fratini M, Cedola A, Bukreeva, I, Asadchikov, V, Buzmakov, A, Chukalina, M, Ingacheva, A, Korolev, N, Bravin, A, Mittone, A, Biella, G, Sierra, A, Brun, F, Massimi, L, Fratini, M, Cedola, A, Bukreeva I, Asadchikov V, Buzmakov A, Chukalina M, Ingacheva A, Korolev NA, Bravin A, Mittone A, Biella GEM, Sierra A, Brun F, Massimi L, Fratini M, and Cedola A

Abstract

A crucial issue in the development of therapies to treat pathologies of the central nervous system is represented by the availability of non-invasive methods to study the threedimensional morphology of spinal cord, with a resolution able to characterize its complex vascular and neuronal organization. X-ray phase contrast micro-tomography enables a highquality, 3D visualization of both the vascular and neuronal network simultaneously without the need of contrast agents, destructive sample preparations or sectioning. Until now, high resolution investigations of the post-mortem spinal cord in murine models have mostly been performed in spinal cords removed from the spinal canal. We present here post-mortem phase contrast micro-tomography images reconstructed using advanced computational tools to obtain high-resolution and high-contrast 3D images of the fixed spinal cord without removing the bones and preserving the richness of micro-details available when measuring exposed spinal cords. We believe that it represents a significant step toward the in-vivo application. (C) 2020 Optical Society of America under the terms of the OSA Open Access Publishing Agreement

Published
2020

23. Processing of x-ray tomographic projections collected in different schemes.

Author

Chukalina, M. V., Arlazarov, V. V., Nikolaev, D. P, Potrakhov, N. N., Gryaznov, A. Yu., and Kostrin, D. K.

Subjects
*X-rays, *OPTICAL elements, *THREE-dimensional imaging, *GRAPHICAL projection, *DETECTORS
Abstract

Since 1971, when the EMI scanner appeared on the market, work on optimizing the hardware of X-ray tomography complexes has not stopped for a single day. X-ray sources are constantly being improved (brighter, more stable, etc.), detectors (increased sensitivity, resolution, etc.), new geometric schemes and modes of projections collecting are being proposed. Another component of the tomographic complex is a computer that implements, in addition to starting measurements and controlling them, pre-processing of collected projections and reconstruction of a 3D digital image of an object, its processing and analysis. This paper presents mathematical approaches to working with tomographic projections collected in different schemes, as the basis for implementing reconstruction algorithms. The words scheme in the work are understood as monochromatic or polychromatic scanning was performed, what type of signal was recorded (transmission, fluorescent, phase contrast), whether the optical element was installed in the optical path. [ABSTRACT FROM AUTHOR]

Published
2020
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27. Noise Reduction Methods in Laboratory of X-ray Microtomography.

Author

Asadchikov, V. E., Buzmakov, A. V., Ingacheva, A. S., Krivonosov, Yu. S., Zolotov, D. A., and Chukalina, M. V.

Subjects
X-ray computed microtomography, NOISE control, TOMOGRAPHY, RADIATION sources, LABORATORIES
Abstract

Laboratory X-ray microtomography is a convenient method of studying the threedimensional structure of objects of different types. Modern laboratory microtomography setups allow us to carry out measurements with submicron resolution. The laboratory sources of X-ray radiations used in such setups have low intensity, so the recorded tomographic projections are noisy. This often leads to the situation when the reconstructed tomographic images are also noisy, and artifacts may appear on them (objects of a characteristic shape, which are absent in the real object). In this work, we describe the methods of noise and artifacts suppression at all stages of data processing: reducing noise in the original projection images, the inclusion of regularizing members in the tomographic reconstruction procedure, filtering of reconstructed data. The reduction of noise and artifacts on tomographic data allows not only to reconstruct the internal structure of the objects under study but also to make a step towards temporal resolution and spectral tomography on laboratory sources. [ABSTRACT FROM AUTHOR]

Published
2020

30. Revisiting the local structure in Ge-Sb-Te based chalcogenide superlattices

Author

Casarin, B., Caretta, A., Momand, J., Kooi, B. J., Verheijen, M.A., Bragaglia, V., Calarco, R., Chukalina, M., Yu, X., Robertson, J., Lange, F.R.L., Wuttig, M., Redaelli, A., Varesi, E., Parmigiani, F., Malvestuto, M., Casarin, B., Caretta, A., Momand, J., Kooi, B. J., Verheijen, M.A., Bragaglia, V., Calarco, R., Chukalina, M., Yu, X., Robertson, J., Lange, F.R.L., Wuttig, M., Redaelli, A., Varesi, E., Parmigiani, F., and Malvestuto, M.

Abstract

The technological success of phase-change materials in the field of data storage and functional systems stems from their distinctive electronic and structural peculiarities on the nanoscale. Recently, superlattice structures have been demonstrated to dramatically improve the optical and electrical performances of these chalcogenide based phase-change materials. In this perspective, unravelling the atomistic structure that originates the improvements in switching time and switching energy is paramount in order to design nanoscale structures with even enhanced functional properties. This study reveals a high- resolution atomistic insight of the [GeTe/Sb2Te3] interfacial structure by means of Extended X-Ray Absorption Fine Structure spectroscopy and Transmission Electron Microscopy. Based on our results we propose a consistent novel structure for this kind of chalcogenide superlattices.

Published
2016

31. High-Resolution X-Ray Fluorescence Microtomography of Homogeneous Samples

Author

Simionovici, A., Chukalina, M., Schroer, C., Drakopoulos, M., Snigirev, A., Snigireva, I., Lengeler, B., Janssens, K., and Adams, F.

Subjects
Fluorescence -- Usage, Tomography -- Methods, X-rays -- Usage, Imaging systems -- Testing, Business, Electronics, Electronics and electrical industries
Abstract

First experimental results of fluorescence microtomography with 6-[micro]m resolution obtained at ESRF, Grenoble, France, are described. The setup comprises high-quality optics (monochromator, mirror, focusing lenses) coupled to the high-energy/brilliance/coherence of the ID 22 undulator beamline. The tomographic setup allows precise measurements in the 'pencil-beam' geometry. The image reconstruction is based on a modification of the algebraic reconstruction method but includes simplifications of the model. The quality and precision of the two-dimensional reconstructed elemental images of a phantom sample are encouraging. The method will be further refined and applied for the analysis of more complex inhomogeneous samples. Index Terms--Algebraic reconstruction method, synchrotron radiation, X-ray fluorescence microtomography, X-ray microprobe.

Published
2000

34. A new FEFF-based wavelet for EXAFS data analysis

Author

Funke, H., Chukalina, M., and Scheinost, A.

Subjects
EXAFS, data evaluation, layered double hydroxides, wavelet transform
Abstract

A new mother wavelet function for extended X-ray absorption fine-structure (EXAFS) data analysis has been designed, combining a model EXAFS function derived from the ab initio EXAFS code FEFF8.20 and the complex Morlet wavelet. This new FEFF–Morlet mother wavelet routine allows the generation of wavelets well adapted to specific EXAFS problems. A substantial gain in resolution of the wavelet ridges in k and r space is achieved. The method is applied to a structural problem of Zn–Al double-layer hydroxides, demonstrating unequivocally the homogeneity of the metal cation distribution in the hydroxide layers.

Published
2007

39. Wavelet analysis of Extendet X-ray Absorption Fine Structure Data

Author

Funke, H., Chukalina, M., and Rossberg, A.

Abstract

Extended Xray absorption fine structure data evaluation usually begins with the Fourier transform of the spectrum. We suggest the wavelet transform as a complement to the Fourier transform. While the Fourier transform analyzes the distances to the backscattering atoms, wavelet transform additionally reveals the wavenumber dependence of the scattering. Thus wavelet analysis can differentiate between heavier and lighter backscattering atoms, even if they are almost equidistant from the central atom. First the method of operation and the advantage of the wavelet analysis will be demonstrated by simple models. Then it is applied to the interpretation of extended Xray absorption fine structure spectra concerning the complexation of UraniumVI with the carboxylic groups acetic, formic, and glycolic acid. The wavelet transform analysis suggests clearly for the system Uraniumformic acid both, UU and UCC, structural elements. In contrast to the clear separation of different scattering paths by wavelet transform, Fourier transform analysis was not able to resolve the two different backscattering processes.

Published
2005

41. Apparatus and computer X-ray tomography: Visualization of intrinsic structure, evaluation of performance and limitations

Author

Chukalina, M., Zaitsev, S., Knyazev, M., Vanegas, C. J., Dmitry Nikolaev, Simionovici, A., Institute of Microelectronics Technology RAS, Institute of microelectronics technology, Institute for Information Transmission Problems, RAS, Institute for Information Transmission Problems, Laboratoire de Sciences de la Terre (LST), École normale supérieure de Lyon (ENS de Lyon)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Institut national des sciences de l'Univers (INSU - CNRS)-Centre National de la Recherche Scientifique (CNRS), Centre National de la Recherche Scientifique (CNRS)-Institut national des sciences de l'Univers (INSU - CNRS)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-École normale supérieure - Lyon (ENS Lyon), and Talour, Pascale

Subjects
Confocal apparatus and computer tomography in medicine, image visualization, dose deposition
Published
2005

42. Wavelet analysis of EXAFS Data

Author

Funke, H., Chukalina, M., Hennig, C., Rossberg, A., and Scheinost, A.

Abstract

wird nachgereicht

Published
2005

44. Wavelet analysis and its application to the Tunneling and X-ray spectroscopy

Author

Chukalina, M., Funke, H., and Dubrovskii, Y.

Subjects
ComputingMethodologies_IMAGEPROCESSINGANDCOMPUTERVISION
Abstract

The capabilities and limitations of wavelet analysis are demonstrated for the illustrative case of two practial applications: investigation of magneto-tunneling signals and the extended x-ray absorption fine structure (EXAFS) of uranium. A brief introduction to wavelet analysis is given. The term "window size" of the mother wavelet function is defined; this concept underlies one of the ideas for a criterion of optimal choice of the mother wavelet function. The capabilities of a software package developed by the authors are demonstrated; this software was used for all the calculations done in the course of this study.

Published
2004

45. X-ray tomography: how to evaluate the reconstruction quality?

Author

Chukalina, M., Golosio, B., Simionovici, A., and Funke, H.

Subjects
Correlation coefficient, X-ray computer tomography, Quality of the reconstruction, Wavelet transform, Reconstruction techniques
Abstract

Different reconstruction techniques are used to reconstruct the distribution of the physical characteristics, describing a sample under investigation, from a set of tomographic projections. We present a technique for the evaluation of the reconstruction quality. The technique is based on the comparison of two images (phantom and reconstructed image) by means of the correlation coefficient and of the mean square error between them. In parallel, the correlation coefficient and mean square error are calculated for the wavelet transforms of the phantom and reconstructed images. The scales for the wavelet transform are chosen in agreement with the major geometric parameters of the phantom. Then the correlation coefficient of the wavelet transform with the chosen scale yields an evaluation of the quality of the phantom parameters reconstruction. The accuracy of the parameters reconstruction is determined by the mean square error for the selected scale. The phantom used for the analysis is a medium with randomly distributed grains. The distribution is characterized by two parameters: grain size and grain density (average number of grains per unit area). The parameters are used as the scales for the wavelet transform calculation. We make a comparison of the Algebraic Reconstruction Technique (ART) and the Filtered Back Projection Algorithm.

Published
2004

49. Improving Resolution in k and r Space: A FEFF-based Wavelet for EXAFS Data Analysis

Author

Funke, H., Chukalina, M., Voegelin, A., Scheinost, A., Funke, H., Chukalina, M., Voegelin, A., and Scheinost, A.

Abstract

Applying the wavelet analysis of Extended X-Ray Absorption Fine Structure (EXAFS) spectra to a Zn-Al layered double hydroxide, we could unequivocally identify the presence of Al and Zn atoms at the same distance of r ≈ 3 Å from the central Zn atom. The focused paths (including MS) at r ≈ 5 - 6 Å (2nd and 3th metal shell) show also both Al and Zn for all LDH spectra. With the newly developed FEFF-Morlet wavelet it is possible to resolve the two shells individually. The result is, that the 2nd shell not contains Al. This confirms directly the homogeneity of the Al - Zn distribution. No significant differences were found by shell fit- and wavelet analysis between the EXAFS spectra of pure Zn-,Co- or Ni LDH on the one hand and the mixed Zn/Co and Zn/Ni LDH on the other hand.

Published
2007

50. Improving Resolution in k and r Space: A FEFF-based Wavelet for EXAFS Data Analysis

Author

Funke, H., Chukalina, M., Voegelin, A., Scheinost, A., Funke, H., Chukalina, M., Voegelin, A., and Scheinost, A.

Abstract

Applying the wavelet analysis of Extended X-Ray Absorption Fine Structure (EXAFS) spectra to a Zn-Al layered double hydroxide, we could unequivocally identify the presence of Al and Zn atoms at the same distance of r ≈ 3 Å from the central Zn atom. The focused paths (including MS) at r ≈ 5 - 6 Å (2nd and 3th metal shell) show also both Al and Zn for all LDH spectra. With the newly developed FEFF-Morlet wavelet it is possible to resolve the two shells individually. The result is, that the 2nd shell not contains Al. This confirms directly the homogeneity of the Al - Zn distribution. No significant differences were found by shell fit- and wavelet analysis between the EXAFS spectra of pure Zn-,Co- or Ni LDH on the one hand and the mixed Zn/Co and Zn/Ni LDH on the other hand.

Published
2006

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