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    Tytuł:
    Ocena metody zbiorów poziomicowych stosowanych do segmentacji trójwymiarowych obrazów fantomów cyfrowych oraz obrazów naczyń krwionośnych mózgu TOF-SWI rezonansu magnetycznego
    Evaluation of level set method in segmentation of 3D digital phantom images and brain vessels TOF-SWI MR images
    Autorzy:
    Strzelecki, M.
    Materka, A.
    Kociński, M.
    Szczypiński, P.
    Deistung, A.
    Reichenbach, J.
    Powiązania:
    https://bibliotekanauki.pl/articles/261815.pdf
    Data publikacji:
    2010
    Wydawca:
    Politechnika Wrocławska. Wydział Podstawowych Problemów Techniki. Katedra Inżynierii Biomedycznej
    Tematy:
    rezonans magnetyczny
    naczynie krwionośne
    3D
    układ krwionośny
    circulatory system
    magnetic resonance
    blood vessel
    Opis:
    W pracy zbadano dokładność metody segmentacji level set stosowanej do analizy trójwymiarowych obrazów fantomów przedstawiających fragmenty naczyń oraz układ drzew krwionośnych. Badano przydatność metody do detekcji cienkich naczyń (o średnicy mniejszej niż rozmiar woksela obrazu) oraz jej odporność na zakłócenia. Oceny metody dokonano za pomocą obiektywnej miary ilościowej opisującej dokładność segmentacji. Metodę level set wykorzystano również do segmentacji rzeczywistych trójwymiarowych obrazów TOF-SWI (Time Of Flight and Susceptibility Weighted Imaging) rezonansu magnetycznego naczyń krwionośnych mózgu wraz z metodą Sato, wykorzystującą filtrację wieloskalową. Wstępne wyniki, w postaci trójwymiarowych modeli naczyń krwionośnych, są obiecujące. W pracy przedstawiono kierunki dalszych badań prowadzących do uzyskania dokładniejszych modeli układu krwionośnego, zwłaszcza dla naczyń o małych średnicach.
    The objective of this work is to evaluate performance of the level set approach applied to segmentation of 3D images of computer-simulated blood-vessel phantoms and artificial vascular trees. The segmentation of thin vessels with diameter smaller than voxel size and influence of noise on segmentation results, were studied. Quantitative measures of segmentation accuracy were used for the methods evaluation. The level set technique was also used for segmentation of 3D TOF-SWI MR (Time Of Flight and Susceptibility Weighted Magnetic Resonance Imaging) brain vessels images. Also, the multiscale filtering approach was applied. Preliminary results in the form of 3D vein and artery models are promising. Further work aimed at more accurate modeling of brain vasculature, focused on thin vessels detection is also addressed.
    Źródło:
    Acta Bio-Optica et Informatica Medica. Inżynieria Biomedyczna; 2010, 16, 2; 167-172
    1234-5563
    Pojawia się w:
    Acta Bio-Optica et Informatica Medica. Inżynieria Biomedyczna
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Segmentacja trójwymiarowych obrazów ToF-SWI RM naczyń krwionosnych mózgu z wykorzystaniem filtracji wieloskalowej
    Segmentation of 3D ToF-SWI brain vessels images by means of multiscale filtering
    Autorzy:
    Strzelecki, M.
    Materka, A.
    Kociński, M.
    Sankowski, A.
    Dwojakowski, G.
    Deistung, A.
    Reinchenbach, J.
    Powiązania:
    https://bibliotekanauki.pl/articles/261987.pdf
    Data publikacji:
    2010
    Wydawca:
    Politechnika Wrocławska. Wydział Podstawowych Problemów Techniki. Katedra Inżynierii Biomedycznej
    Tematy:
    segmentacja obrazów 3D
    filtracja wieloskalowa
    morfologia matematyczna
    obrazy 3D ToF-SWI MR układu krwionośnego mózgu
    3D image segmentation
    muitiscale filtering
    mathematical morphology
    3D T o F - S W I MR images of brain vaculature
    Opis:
    W pracy przedstawiono wyniki bada ń dotyczących trójwymiarowych metod analizy obrazów 3D rezonansu magnetycznego naczyń krwionośnych mózgu. Scharakteryzowano sekwencje sygnałów skanera MM (rezonansu magnetycznego) wykorzystywane do uzyskania obrazów angiograficznych mózgu. Przedstawiono również wyniki segmentacji drzewa naczyń z wykorzystaniem filtracji wieloskalowej oraz elementów morfologii matematycznej. Przedstawiono kierunki przyszłych badań prowadzących do opracowania połączenia między analizą makro- i mikronaczyń, celem uzyskania dokładniejszych modeli układu krwionośnego.
    The paper presents the analysis c f 3 0 ToF-SWI magnetic resonance images of brain vessels. T h e MR (magnetic resonance) sequences of ToF (Time of Flight) and SWI (Susceptibility Weighted Imaging) used for acquisition of vasculature images, were characterized. The segmentation results of vessel images, based on muitiscale filtering and mathematical morphology methods, were presented and discussed. Finally, more precise and accurate brain vasculature model, was introduced.
    Źródło:
    Acta Bio-Optica et Informatica Medica. Inżynieria Biomedyczna; 2010, 16, 4; 367-371
    1234-5563
    Pojawia się w:
    Acta Bio-Optica et Informatica Medica. Inżynieria Biomedyczna
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Helical Spin Structures in c-Axis Dy/Y Superlattice
    Autorzy:
    Seroczyńska, M.
    Kociński, J.
    Powiązania:
    https://bibliotekanauki.pl/articles/1943983.pdf
    Data publikacji:
    1996-01
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    75.70.Fr
    75.70.-i
    Opis:
    On the basis of Landau's theory of symmetry changes at continuous phase transitions, we have derived the formulae for two incommensurate helical spin structures which are symmetry allowed in Dy/Y superlattice, when the helical axis is parallel to the c-axis of the hexagonal lattice. These structures have different extinction coefficients in their cross-sections for magnetic scattering of neutrons and therefore can be distinguished by experiment. Magnetic satellite peaks around the reciprocal lattice points K + 0 are allowed for only one of these spin structures, namely that inferred from earlier experiments.
    Źródło:
    Acta Physica Polonica A; 1996, 89, 1; 99-104
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Binaural masking of amplitude modulation
    Autorzy:
    Kordus, M.
    Sęk, A.
    Kociński, J.
    Powiązania:
    https://bibliotekanauki.pl/articles/177557.pdf
    Data publikacji:
    2005
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    masking
    masking in the modulation domain
    modulation filterbank
    Opis:
    A new concept concerned with the transformation of acoustic stimuli in the auditory system postulates the existence of a form of spectral analysis applied to the amplitude changes of the stimuli. It is assumed that this analysis takes place in the so-called modulation filters, i.e. bandpass linear filters tuned to different rates of the amplitude changes. The most striking argument supporting this idea is an effect of masking in the amplitude modulation domain whose nature can be easily explained basing on this concept. As the modulation filters are situated on the higher levels of the auditory system, it is also assumed that this form of masking is entirely a central process. However, most of the studies concerned with masking in the modulation domain used monaural listening only. Therefore, the main purpose of the presented here experiments was to investigate whether this type of masking is entirely a central process. Using a Three-Alternative Forced-Choice (3AFC) procedure the binaural and monaural masked thresholds of amplitude modulation were determined. A sinusoidal carrier at a frequency of 4 kHz was amplitude modulated by a specially designed band of noise characterized by a very low value of the crest factor, which was used as a masking signals. Different bandwidths of the modulating masking signals were used as well as different center frequencies to investigate whether the masking patterns in the modulation domain depend on the masker bandwidth and its center frequency. The modulating target (masked) signal was a pure tone at a frequency range from 2 to 256 Hz. Both modulating signals were applied to the same sinusoidal carrier signal. The most effective masking was noticed when the rate of the sinusoidal modulation was close to the center frequency of the masking signal or when it was in its spectral range and decreased outside of this range. The character of this dependence confirms the existence of some form of a frequency selectivity in the modulation rate domain similarly to the audible frequency domain. The thresholds for monaural and binaural listening were very close to each other. This implies that masking in the modulation domain is a central process.
    Źródło:
    Archives of Acoustics; 2005, 30, 1; 5-17
    0137-5075
    Pojawia się w:
    Archives of Acoustics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Convolutive Blind Signal Separation Spatial Effectiveness in Speech Intelligibility Improvement
    Autorzy:
    Kociński, J.
    Sęk, A.
    Libiszewski, P.
    Powiązania:
    https://bibliotekanauki.pl/articles/1504381.pdf
    Data publikacji:
    2011-06
    Wydawca:
    Polska Akademia Nauk. Instytut Fizyki PAN
    Tematy:
    43.72.-p
    43.60.-c
    43.60.+d
    Opis:
    Blind signal separation is one of the latest methods to improve the signal to noise ratio. The main objective of blind source separation is the transformation of mixtures of recorded signals to obtain each source signal at the output of the procedure, assuming that they are statistically independent. For acoustic signals it can be concluded that the correct separation is possible only if the source signals are spatially separated. That finding suggests analogies with the classical spatial filtering (beamforming). In this study we analyzed an effect of the angular separation of two source signals (i.e. speech and babble noise) to improve speech intelligibility. For this purpose, we chose the blind source separation algorithm based on the convolutive separation, based on second order statistics only. As a system of sensors a dummy head was used (one microphone inside each ear canal), which simulated two hearing aids of a hearing impaired person. The speech reception threshold, before and after the blind source separation was determined. The results have shown significant improvement in speech intelligibility after applying blind source separation (speach reception threshold fell even more than a dozen dB) in cases where the source signals were angularly separated. However, in cases where the source signals were coming from the same directions, the improvement was not observed. Moreover, the effectiveness of the blind source separation, to a large extent, depended on the relative positions of signal sources in space.
    Źródło:
    Acta Physica Polonica A; 2011, 119, 6A; 996-999
    0587-4246
    1898-794X
    Pojawia się w:
    Acta Physica Polonica A
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Logatome and Sentence Recognition Related to Acoustic Parameters of Enclosures
    Autorzy:
    Kociński, J.
    Ozimek, E.
    Powiązania:
    https://bibliotekanauki.pl/articles/176289.pdf
    Data publikacji:
    2017
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    STI
    Speech Transmission Index
    speech intelligibility
    reverberation time
    Opis:
    The paper deals with relationship between speech recognition and objective parameters of enclosures. Six enclosures were chosen: a church, an assembly hall of a music school, two courtrooms of different volumes, a typical auditorium and a university concert hall. Dirac 4.1 software was used to record impulse responses (IRs) in the chosen measurement points of each enclosure. On this base, the following objective parameters of the enclosure were determined: Reverberation Time (RT), Early Decay Time (EDT), Weighted Clarity (C50) and Speech Transmission Index (STI). A convolution of the IRs with logatome tests and the Polish Sentence Test (PST) was made. Logatome recognition and speech reception threshold (SRT – i.e., SNR yielding 50% speech recognition) were evaluated and their dependence on the objective parameters were determined. Generally a linear relationship between logatome or SRT and RT or EDT was found. However, speech recognition was nonlinearly related (according to psychometric function) to STI values. The most sensitive range of the logatome and sentence recognition relative to STI changes corresponded to the middle range of STI values. Below and above this range, logatome and sentence recognition were much less dependent of STI changes.
    Źródło:
    Archives of Acoustics; 2017, 42, 3; 385-394
    0137-5075
    Pojawia się w:
    Archives of Acoustics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Speech Intelligibility in Rooms with and without an Induction Loop for Hearing Aid Users
    Autorzy:
    Kociński, J.
    Ozimek, E.
    Powiązania:
    https://bibliotekanauki.pl/articles/177905.pdf
    Data publikacji:
    2015
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    speech intelligibility
    induction loop
    hearing impairment
    speech enhancement
    Opis:
    The paper presents the results of sentence and logatome speech intelligibility measured in rooms with induction loop for hearing aid users. Two rooms with different acoustic parameters were chosen. Twenty two subjects with mild, moderate and severe hearing impairment using hearing aids took part in the experiment. The intelligibility tests composed of sentences or logatomes were presented to the subjects at fixed measurement points of an enclosure. It was shown that a sentence test is more useful tool for speech intelligibility measurements in a room than logatome test. It was also shown that induction loop is very efficient system at improving speech intelligibility. Additionally, the questionnaire data showed that induction loop, apart from improving speech intelligibility, increased a subject’s general satisfaction with speech perception.
    Źródło:
    Archives of Acoustics; 2015, 40, 1; 51-58
    0137-5075
    Pojawia się w:
    Archives of Acoustics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
    Tytuł:
    Speech Recognition in an Enclosure with a Long Reverberation Time
    Autorzy:
    Kociński, J.
    Ozimek, E.
    Powiązania:
    https://bibliotekanauki.pl/articles/177544.pdf
    Data publikacji:
    2016
    Wydawca:
    Polska Akademia Nauk. Czytelnia Czasopism PAN
    Tematy:
    speech intelligibility
    speech recognition
    sentence test
    reverberation time
    clarity
    speech transmission index
    Opis:
    The aim of this work was to measure subjective speech intelligibility in an enclosure with a long reverberation time and comparison of these results with objective parameters. Impulse Responses (IRs) were first determined with a dummy head in different measurement points of the enclosure. The following objective parameters were calculated with Dirac 4.1 software: Reverberation Time (RT), Early Decay Time (EDT), weighted Clarity (C50) and Speech Transmission Index (STI). For the chosen measurement points, a convolution of the IRs with the Polish Sentence Test (PST) and logatome tests was made. PST was presented at a background of a babble noise and speech reception threshold – SRT (i.e. SNR yielding 50% speech intelligibility) for those points were evaluated. A relationship of the sentence and logatome recognition vs. STI was determined. It was found that the final SRT data are well correlated with speech transmission index (STI), and can be expressed by a psychometric function. The difference between SRT determined in condition without reverberation and in reverberation conditions appeared to be a good measure of the effect of reverberation on speech intelligibility in a room. In addition, speech intelligibility, with and without use of the sound amplification system installed in the enclosure, was compared.
    Źródło:
    Archives of Acoustics; 2016, 41, 2; 255-264
    0137-5075
    Pojawia się w:
    Archives of Acoustics
    Dostawca treści:
    Biblioteka Nauki
    Artykuł
      Wyświetlanie 1-8 z 8

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