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1
Content available Relaxing the WDO Assumption in Blind Extraction of Speakers from Speech Mixtures
100%
Kasprzak W. , Ding N. , Hamada N.
Journal of Telecommunications and Information Technology
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2010
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tom nr 4
50-58
EN
The time-frequency masking approach in blind speech extraction consists of two main steps: feature clustering in a space spanned over delay-time and attenuation rate, and spectrogram masking in order to reconstruct the sources. Usually a binary mask is generated under the strong W-disjoint orthogonal (WDO) assumption (disjoint orthogonal representations in the frequency domain). In practice, this assumption is most often violated leading to weak quality of reconstructed sources. In this paper we propose the WDO to be relaxed by allowing some frequency bins to be shared by both sources. As we detect instantaneous fundamental frequencies the mask creation is supported by exploring a harmonic structure of speech. The proposed method is proved to be effective and reliable in experiments with both simulated and real acquired mixtures.
2
Content available remote Measurement of core loss in single sheet tester
100%
Tamaki T. , Fujisaki K. , Yabumoto M. , Hamada N.
Przegląd Elektrotechniczny
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2007
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tom R. 83, nr 4
14-17
PL
Straty mierzone testerem SSTz pośrednim magnesowaniem (gdzie próbka jest magnesowana za pośrednictwem rdzenia z cewkami magnesującymi) nie zawsze korespondują ze stratami mierzonymi testerem o bezpośrednim magnesowaniu (gdzie próbka jest umieszczona wewnątrz cewek magnesujących). W obu typach testerów czujniki H i B mają szerokość porównywalna z wymiarami próbki. Straty mierzone testerem o magnesowaniu pośrednim wykorzystującym zbyt małe czujniki różnią się od strat mierzonych testerem o bezpośrednim magnesowaniu.
EN
The core loss measured with the indirect magnetizing single sheet tester (SST) (in which a sample is placed between yokes and is indirectly magnetized by the yokes magnetized by magnetizing coils) roughly corresponds with that measured with the direct magnetizing SST used as standard (in which a sample is placed inside a magnetizing coil and is directly magnetized by the magnetizing coil). Both the SSTs have the B coil and the H coil whose widths are the same as the sample width. However, the core loss measured with the indirect magnetizing SST using the small size of the B coil and the H coil is much different from that measured with the direct magnetizing SST.
3
Phytotoxicities of the invasive species Plantago major and non-invasive species Plantago asiatica
100%
Kato-Noguchi H. , Hamada N. , Clements D. R.
Acta Physiologiae Plantarum
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2015
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tom 37
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nr 03
EN
Although Plantago major and Plantago asiatica have similar life-history characteristics, P. major populations expand much more rapidly than P. asiatica in habitats where both species occur. One potential factor contributing to this disparity is the production of phytotoxic compounds. However, the phytotoxic characteristics of P. major and P. asiatica have not yet reported. Therefore, we conducted an investigation of possible phytotoxic compounds with allelopathic activity in both species. Aqueous methanol extracts of both plant species inhibited root and hypocotyl growth of garden cress (Lepidium sativum) in a concentration dependent manner. However, the inhibitory effect of P. major was greater than that of P.asiatica. The extracts were further purified by several chromatographic runs and two main phytotoxic compounds were isolated and identified through spectral analysis as (-)-3-hydroxy-β-ionone and blumenol A. (-)-3-Hydroxy-β-ionone and blumenol A inhibited the growth and germination of garden cress at concentrations greater than 1 and 30 lM, respectively. The level of (-)-3-hydroxy-β-ionone in P. major was 7.2-fold greater than that in P. asiatica, while the level of blumenol A was equal in both plant species. Although these Plantago species produce two main phytotoxic compounds with allelopathic activity, the higher level of (-)-3-hydroxy-β-ionone in P. major may result in it contributing the primary inhibitory effects of the extract of P. major. (-)-3-hydroxy-β-ionone may also serve to distinguish the invasive habit of two species and may be involved in the expansion in habitats of P. major.
4
Nonproportional low cycle fatigue lives of type 304 and 316 stainless steels at high temperature
100%
Itoh T. , Hamada N. , Sakane M.
Zeszyty Naukowe. Mechanika / Politechnika Opolska
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2001
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tom z. 68
395-402
EN
This paper describes the effect of nonproportional loading on low cycle fatigue lives for type 304 and 316FR stainless steels at room temperature an 923K, respectively. Strain controlled tension-torsion low cycle fatigue tests were carried out using hollow cylinder specimens under two proportional and thirteen nonproportional strain paths at a strain rate of 0.1%/s. Nonproportional straining significantly reduced fatigue lives of the steels at room temperature and 923K. Reduction of the live due to the nonproportional straining reached about 10% compared with the proportional lives in specific strain paths. Nonproportional strain range proposed, delta(epsilon(NP)), successfully correlated the nonproportional fatigue lives but the equivalent strain defined in ASME code case gave a significantly unconservative prediction for the steels.
5
Content available Estimation and tracking of fundamental, 2nd and 3d harmonic frequencies for spectrogram normalization in speech recognition
100%
Fujimoto K. , Hamada N. , Kasprzak W.
Bulletin of the Polish Academy of Sciences. Technical Sciences
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2012
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tom Vol. 60, nr 1
71-81
EN
A stable and accurate estimation of the fundamental frequency (pitch, F0) is an important requirement in speech and music signal analysis, in tasks like automatic speech recognition and extraction of target signal in noisy environment. In this paper, we propose a pitch-related spectrogram normalization scheme to improve the speaker – independency of standard speech features. A very accurate estimation of the fundamental frequency is a must. Hence, we develop a non-parametric recursive estimation method of F0 and its 2nd and 3d harmonic frequencies in noisy circumstances. The proposed method is different from typical Kalman and particle filter methods in the way that no particular sum of sinusoidal model is used. Also we tend to estimate F0 and its lower harmonics by using novel likelihood function. Through experiments under various noise levels, the proposed method is proved to be more accurate than other conventional methods. The spectrogram normalization scheme makes a mapping of real harmonic structure to a normalized structure. Results obtained for voiced phonemes show an increase in stability of the standard speech features – the average within-phoneme distance of the MFCC features for voiced phonemes can be decreased by several percent.
6
Content available Estimation and tracking of fundamental, 2nd and 3d harmonic frequencies for spectrogram normalization in speech recognition
75%
Fujimoto K. , Kasprzak W. , Hamada N.
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nr 1
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