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Wyświetlanie 1-15 z 21
Tytuł:
Discrete Time Model for Bond Detection in Thin Layer Materials
Autorzy:
Ali, M.
Elsayed, N.
Hassan, G.
Powiązania:
https://bibliotekanauki.pl/articles/1419712.pdf
Data publikacji:
2012-07
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
43.60.+d
Opis:
Recursive equations were developed and introduced that enable to calculate the transmitted waves through a multiplicity of layers. The calculations are carried out using z-transform technique. The layers are considered lossless and have parallel interface, which are at normal incidence to the field. The multilayered structures are constructed of three aluminum plates connected together with epoxy as the adhesive layers. The method has been successfully used to detect small changes in the thickness of adhesive layers.
Źródło:
Acta Physica Polonica A; 2012, 122, 1; 82-84
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
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:
Adaptive Approach to Acoustic Car Driving Detection in Mobile Devices
Autorzy:
Aksamit, P.
Powiązania:
https://bibliotekanauki.pl/articles/1399332.pdf
Data publikacji:
2013-09
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
43.60.Vx
43.60.-c
43.60.+d
43.60.Mn
Opis:
The context awareness of mobile devices is broadly researched area as it improves the functionality, usability, safety of usage and intelligence of the device as perceived by its user. The special type of context is driving a car. The awareness of a mobile device whose user drives a car may allow to disable some features like making and taking phone calls and enable other features like e.g. navigation thus improving the safety of the user. The paper presents the results of a research on acoustic detection of car driving based on over 60 h of collected data. The modification of traditional k-nearest neighbors classification algorithm is proposed that allows for learning and adaptation of classifier configuration. The proposed approach significantly improves both the sensitivity and specificity of the classifier comparing to the classifier based only on offline training data. The challenges in performing the acoustic wave analysis using highly heterogeneous devices like mobile phones are discussed.
Źródło:
Acta Physica Polonica A; 2013, 124, 3; 381-383
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Analysis and Elaboration of an Air-Coupled Ultrasound Wideband Sensor Array
Autorzy:
Herman, K.
Stach, L.
Powiązania:
https://bibliotekanauki.pl/articles/1400279.pdf
Data publikacji:
2013-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
43.60.Fg
43.60.Vx
43.60.-c
43.60.+d
Opis:
In this paper a design process of 64 sensor matrix is described. This study presents adaptation of well known sonar engineering methods of analysis in order to design air operating ultrasound beamforming system. The elaborated system is based on wideband micro electro-mechanical systems. A full digital beamformer with advanced digital signal processing block description is also included. The main goal of the system is direct of arrival of ultrasound wave estimation.
Źródło:
Acta Physica Polonica A; 2013, 123, 1; 31-33
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Cardiac Activity Based on Acoustic Signal Properties
Autorzy:
Czopek, K.
Powiązania:
https://bibliotekanauki.pl/articles/1490378.pdf
Data publikacji:
2012-01
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
43.60.-c
43.60.+d
87.19.ug
Opis:
The influence of sleeping conditions on human health and well-being is now fully understood, but still underestimated. Sleep disorders e.g. snoring, wheezing or sleep apnea are widespread among people of all ages, although prevalent amidst the male population, obese people with a high value of BMI, people who suffered a stroke, have hypertension or other heart diseases. Medical support is needed in order to ensure a good night's sleep for patients suffering from sleep disorders. Sleep monitoring is also very important in case of emergencies. This research was aimed at finding a correlation between sleep disorders represented by acoustic signals and heart activity parameters. The measurement of breathing through simultaneously acquired acoustic and ECG signals is used to quantify the respiratory obstruction during sleep. The information collected by synchronized recording of acoustic effects and the ECG signal partly overlaps, giving an opportunity to improve accuracy of measurement. Results indicate that the aspect of sleep analysis can be extended using this method. The information collected by simultaneous recording of acoustic effects and the ECG signal is provided and the results are described.
Źródło:
Acta Physica Polonica A; 2012, 121, 1A; A-042-A-045
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Precise Psychoacoustic Correction Method Based on Calculation of JND Level
Autorzy:
Piotrowski, Z.
Powiązania:
https://bibliotekanauki.pl/articles/1807748.pdf
Data publikacji:
2009-09
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
43.66.-x
43.66.+y
43.60.-c
43.60.+d
Opis:
This paper constitutes a proposal of a method of spectral shaping of the watermark signal without adjusting the interception point based directly on psychoacoustics of the human auditory system and the proposed calculation formula. The proposed calculation formula enables correction of watermark signal both as regards its spectrum shape and adjustment of watermark signal to the host's JND.
Źródło:
Acta Physica Polonica A; 2009, 116, 3; 375-379
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Perceptual Evaluation of the Effect of Threshold in Selective Mixing of Sounds
Autorzy:
Kleczkowski, P.
Pluta, M.
Powiązania:
https://bibliotekanauki.pl/articles/1196825.pdf
Data publikacji:
2014-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
43.60.Hj
43.60.+d
43.75.Zz
43.66.Lj
Opis:
Signal processing methods make possible such a mixing of signals that their overlapping in the time-frequency plane is reduced. This can be achieved by reducing the number of overlapping signals by discarding contributions from weaker signals and leaving only contributions from stronger ones. When applied to acoustic signals, this is referred to by the authors as selective mixing of sounds. Previous research has shown, that this rule, when applied to signals of musical instruments can provide some perceptual advantages over simple adding up the sound sources. In this paper, an experiment was carried out to determine the threshold of the value of relative energy of sound sources to control the decision about discarding a contribution from a particular sound source.
Źródło:
Acta Physica Polonica A; 2014, 125, 4A; A-117-A-121
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Intraoperative Impedance Measurements for the Evaluation of Perimodiolar Location οf Cochlear Implant Electrode - Own Experience
Autorzy:
Stieler, O.
Karlik, M.
Szyfter, W.
Powiązania:
https://bibliotekanauki.pl/articles/1537554.pdf
Data publikacji:
2010-07
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
43.90.+v
43.58.-e
43.60.-c
43.60.+d
Opis:
Evaluation of insertion of a cochlear implant electrode into the cochlea includes radiological techniques: plain X-ray of the skull, cochlear projection (based on Stenvers projection), computer tomography. These methods allow generally postoperative evaluation. During surgery the insertion of the electrode is assessed based on anatomical structures and markers placed on the electrode. The measurement of the electrode impedance is also an important tool. 60 patients implanted with the Contour cochlear implant with pre-shaped electrode were examined. Age o patients: mediana 4.25 (1.5-54.5). Examination includes intraoperative impedance measurement performed in two stages: (1) after the electrode insertion, and (2) after removal of the stylet. Measurements were done in Common Ground (CG) and Monopolar 1 (MP1) stimulation modes. Measurements recorded in two modes and in 3 different parts of the cochlea (apical, middle, basal) were compared. The average difference value (before-after) was for the CG mode: 0.45 kΩ, and for the MP1 mode: 0.39 kΩ. For the CG mode the difference values were: 0.64, 0.44 and 0.28 toward apical part. For the MP1 mode the difference values were: 0.47, 0.43 and 0.27 toward apical part of the cochlea.
Źródło:
Acta Physica Polonica A; 2010, 118, 1; 161-163
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Multi-Channel Sound Synthesis System in Open Area. A Case Study with the Use of FEM
Autorzy:
Ciesielka, W.
Filipek, R.
Powiązania:
https://bibliotekanauki.pl/articles/1197540.pdf
Data publikacji:
2014-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
43.50.Ki
43.55.Jz
43.55.Ka
43.60.+d
Opis:
This paper presents a new model of the multi-channel sound synthesis system. The research objective was to design and construct a sixteen-channel sound control system located in an open area with dimensions of 23.48 m×17.48 m. The main goal of the system operation is to provide, for the controlled acoustic field, the uniformity of the parameters distribution while minimizing the sound pressure level in the protected area. The modeling and simulation researches have been performed using the Finite Element Method (FEM). The results of the analysis include distributions of the sound pressure levels and phase angle for the selected frequencies. The paper presents results of sensitivity studies and optimization for different variants of the sound synthesis system.
Źródło:
Acta Physica Polonica A; 2014, 125, 4A; A-88-A-92
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
An Improved Method of Linear Travel-Time Interpolation Ray Tracing Algorithm
Autorzy:
Hao-Quan, W.
Powiązania:
https://bibliotekanauki.pl/articles/1535590.pdf
Data publikacji:
2010-10
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
07.05.Pj
42.30.Wb
43.60.+d
Opis:
The linear travel-time interpolation algorithm is improved by the method of ray tracing based on finite difference scheme of eikonal equation. It can simulate the more complex medium. Using the algorithm to calculate travel-time and paths of tracing rays, it is more rapid and accurate than the other conventional methods. The linear travel-time interpolation ray tracing algorithm has a drawback: rays cannot go round the low velocity area if the launching point, the receiving point and the low velocity area distribute on the same column (row). Aiming at the drawback, an improved algorithm is proposed on the basis of researching reconstruction theories. The given algorithm adopts a cross-scanning strategy to carry out forward processing and uses discrete points as the secondary sources to simplify backward processing. The numerical simulation experiments show that the rays can go round the low velocity areas located in the same column (row) of the launching points and the receiving points. Rays scan over the global region only once.
Źródło:
Acta Physica Polonica A; 2010, 118, 4; 521-526
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Chaotic Time-Reversed Acoustics: Sensitivity οf the Loschmidt Echo to Perturbations
Autorzy:
Taddese, B.
Johnson, M.
Hart, J.
Antonsen, T.
Ott, E.
Anlage, S.
Powiązania:
https://bibliotekanauki.pl/articles/1585110.pdf
Data publikacji:
2009-11
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
03.55.Kk
05.45.Mt
43.58.+z
43.60.+d
Opis:
We experimentally demonstrate a new acoustic sensor based on the concept of quantum mechanical scattering fidelity and the Loschmidt echo applied to classical acoustic waves in air. The sensor employs a one-recording-channel time-reversal mirror that exploits spatial reciprocity to sensitively measure the classical analog of the scattering fidelity of an enclosed region. The experiments are carried out in a stairwell using a simple speaker and microphone. The input is a 7.0 kHz signal that is amplitude modulated with a 1 ms long pulse. We examine the sensitivity of the time-reversed reconstructed pulse to phase noise, long term drift, and to typical perturbations caused by the rotation of an object in the scattering environment.
Źródło:
Acta Physica Polonica A; 2009, 116, 5; 729-732
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Recurrence Quantification Analysis of Lorenz Model Periodically Modulated at the Onset of Chaos
Autorzy:
Babinec, P.
Krafčík, A.
Powiązania:
https://bibliotekanauki.pl/articles/1493371.pdf
Data publikacji:
2011-09
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
05.40.-a
87.10.Mn
43.60.+d
43.71.+m
Opis:
Plots and quantitative measures obtained from recurrence quantification analysis - recurrence rate, determinism, entropy, and trapping time, were used for the sensitive detection of transitions from laminar (regular) to turbulent (chaotic) phases in the Lorenz model periodically modulated at the onset of chaos.
Źródło:
Acta Physica Polonica A; 2011, 120, 3; 368-370
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Ultrasound Frequency Analysis of a Magnetic Fluid in Low-Intensity External Magnetic Field
Autorzy:
Kurimský, J.
Rajňák, M.
Cimbala, R.
Dolník, B.
Tóthová, J.
Paulovičová, K.
Timko, M.
Kopčanský, P.
Kolcunová, I.
Petráš, J.
Džmura, J.
Balogh, J.
Powiązania:
https://bibliotekanauki.pl/articles/1032764.pdf
Data publikacji:
2017-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
43.58.+z
43.60.+d
47.65.Cb
82.70.Dd
83.80.Hj
Opis:
This work deals with an interaction of a magnetic fluid of a dielectric nature with a magnetic field by means of ultrasound waves measurements and analysis. Ultrasound analysis is known as a non-destructive inspection tool often used in technical diagnostics, moreover, it has numerous applications in medicine and biology, too. We report the low-frequency ultrasound analysis of a dielectric magnetic fluid in a low-intensity external static magnetic field. The studied magnetic fluid was composed of a transformer oil and dispersed magnetite nanoparticles coated with oleic acid. Experiments were carried out by using an ultrasonic testing cell. The cell was exposed to a magnetic field of 50 mT in both parallel and perpendicular direction to the waves propagation. A through-transmission mode measurement was applied, where two fixed narrow-band transducers with completely shielded crystal for maximum RFI/EMI immunity (Physical Acoustic R15I-AST, the resonant frequency 150 kHz) served as a transmitter and a receiver. In this way we carried out the measurement of the frequency-dependent ultrasonic response to a rectangle calibrating signal of 5 μs pulse width. Digitized signals were recorded for further analysis. We present the frequency domain analysis of the low-frequency ultrasound in magnetic fluid. The frequency spectrum in magnetic fluid colloidal system was calculated by the Fourier transformation method. Results show that there is a frequency shift in the amplitude-frequency spectrum caused by the step-up magnetic field. The higher the magnetic field, the higher the frequency of the peaks. The effect of particle aggregation in magnetic field on the ultrasound wave propagation is discussed in the paper.
Źródło:
Acta Physica Polonica A; 2017, 131, 4; 910-912
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
An Analysis of a Mutual Capacitance οf SAW Periodic Strips Having Different Metallization Ratio
Autorzy:
Kawalec, A.
Powiązania:
https://bibliotekanauki.pl/articles/1811552.pdf
Data publikacji:
2008-12
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
02.70.Hm
02.60.-x
07.07.Mp
43.60.+d
77.65.Dq
Opis:
The analytical expression for mutual capacitance of periodic strips is presented in this paper. This expression utilizing the spectral theory is obtained. It is studied how the metallization ratio affects a mutual capacitance of periodic strips. The mutual capacitance of periodic strips as a function of metallization ratio, for split electrodes, was shown in the paper. This approach should be applicable to modeling of the surface acoustic waves interdigital transducers.
Źródło:
Acta Physica Polonica A; 2008, 114, 6A; A-139-A-142
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
High Performance of Electroacoustic Piezoelectric Ceramic Transducers
Autorzy:
Abd El-Ati, M. I.
Mosaad, M. M.
El-Baradie, B.Y.
Powiązania:
https://bibliotekanauki.pl/articles/1920644.pdf
Data publikacji:
1992-04
Wydawca:
Polska Akademia Nauk. Instytut Fizyki PAN
Tematy:
43.35.+d
77.60.+v
Opis:
Lead zirconate-titanate containing 1 wt % niobium with different Zr/Ti ratios compositions were studied. A pronounced increase in densification during sintering process occurred near tetragonal-rhombohedral phase. Dielectric constant of polarized and unpolarized samples was studied. The rotation of all 90° domains to their original positions caused the more looseness of Ti$\text{}^{4+}$ and Zr$\text{}^{4+}$ in the octahedral configuration leading to greater polarization in the tetragonal structure, thus leading to, higher dielectric constant. Near the phase change, the minimum resonance frequency caused the minimum values of ultrasonic waves, which were emitted from the edge of the polarized ceramic transducers.
Źródło:
Acta Physica Polonica A; 1992, 81, 4-5; 527-533
0587-4246
1898-794X
Pojawia się w:
Acta Physica Polonica A
Dostawca treści:
Biblioteka Nauki
Artykuł
Wyświetlanie 1-15 z 21

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