| 1. |
- Stasiunas, Antanas, et al.
(författare)
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A multi-channel adaptive nonlinear filtering structure realizingsome properties of the hearing system
- 2005
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Ingår i: Computers in Biology and Medicine. - Amsterdam : Elsevier. - 0010-4825 .- 1879-0534. ; 35:6, s. 495-510
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Tidskriftsartikel (refereegranskat)abstract
- An adaptive nonlinear signal-filtering model of the cochlea is proposed based on the functional properties of the inner ear. The model consists of the cochlear filtering segments taking into account the longitudinal, transverse and radial pressure wave propagation. On the basis of an analytical description of different parts of the model and the results of computer modeling, the biological significance of the nonlinearity of signal transduction processes in the outer hair cells, their role in signal compression and adaptation, the efferent control over the characteristics of the filtering structures (frequency selectivity and sensitivity) are explained. © 2004 Elsevier Ltd. All rights reserved.
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| 2. |
- Stasiunas, Antanas, et al.
(författare)
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A non-linear circuit for simulating OHC of the cochlea
- 2003
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Ingår i: Medical Engineering and Physics. - London : Elsevier. - 1350-4533 .- 1873-4030. ; 25:7, s. 591-601
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Tidskriftsartikel (refereegranskat)abstract
- In the present paper, referring to known characteristics of the outer hair cells functioning in the cochlea of the inner ear, a functional model of the outer hair cells is constructed. It consists of a linear feed-forward circuit and a non-linear positive feedback circuit. The feed-forward circuit reflects the contribution of local basilar and tectorial membrane areas and passive outer hair cells’ physical parameters to the forming of low-selectivity resonance characteristics. The non-linear positive feedback circuit reflects the non-linear outer hair cell signal transduction processes and the active role of efferents from the medial superior olive in altering circuit sensitivity and selectivity.Referring to an analytical description of the circuit model and computer simulation results, an explanation is given over the biological meaning of the outer hair cells’ non-linearities in signal transduction processes and the role of the non-linearities in achieving the following: signal compression, the dependency of circuit sensitivity and frequency selectivity upon the input signal amplitude, the compatibility of high-frequency selectivity and short transient response of the biological filtering circuits.
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| 3. |
- Stasiunas, Antanas, et al.
(författare)
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A Serial-Parallel Panoramic Filter Bank as a Model of Frequency Decomposition of Complex Sounds in the Human Inner Ear
- 2011
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Ingår i: Informatica (Vilnius). - Amsterdam : IOS Press. - 0868-4952 .- 1822-8844. ; 22:2, s. 259-278
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Tidskriftsartikel (refereegranskat)abstract
- We consider that the outer hair cells of the inner ear together with the local structuresof the basilar membrane, reticular lamina and tectorial membrane form the primary filters (PF) ofthe second order. Taking into account a delay in transmission of the excitation signal in the cochleaand the influence of the Reissner membrane, we design a signal filtering system consisting of thePF with the common PF of the neighboring channels. We assess the distribution of the centralfrequencies of the channels along the cochlea, optimal number of the PF constituting a channel,natural frequencies of the channels, damping factors and summation weights of the outputs of thePF. As an example, we present a filter bank comprising 20 Gaussian-type channels each consistingof five PF. The proposed filtering system can be useful for designing cochlear implants based onbiological principles of signal processing in the cochlea.
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| 4. |
- Stasiunas, Antanas, et al.
(författare)
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An adaptive functional model of the filtering system of the cochlea of the inner ear
- 2011
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Ingår i: Proceedings of the 4th Imternational Symposium on Applied Sciences in Biomedical and Communication Technologies, ISABEL 2011. - New York, NY, USA : ACM Press. - 9781450309134 ; , s. -6
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Konferensbidrag (refereegranskat)abstract
- Outer hair cells (OHC) in the cochlea of the inner ear, together with the local structures of the basilar membrane, reticular lamina and tectorial membrane, constitute the adaptive primary filters (PF) of the second order. We used them for designing a serial-parallel signal filtering system. We determined a rational number of PF included in Gaussian channels of the system, summation weights of the output signals, and distribution of PF along the basilar membrane. A Gaussian channel consisting of five PF is presented as an example, and properties of the channel operating in the linear and non-linear mode are determined during adaptation and under efferent control. The results suggest that application of biological filtering principles can be useful for designing of cochlear implants with new strategies of speech encoding.
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| 5. |
- Stasiunas, Antanas, et al.
(författare)
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An adaptive model simulating the somatic motility and the active hair bundle motion of the OHC
- 2009
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Ingår i: Computers in Biology and Medicine. - New York : Pergamon. - 0010-4825 .- 1879-0534. ; 39:9, s. 800-809
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Tidskriftsartikel (refereegranskat)abstract
- The outer hair cells (OHC) of the mammalian inner ear change the sensitivity and frequency selectivity of the filtering system of the cochlea using two kinds of mechanical activity: the somatic motility and the active hair bundle motion. We designed a non-linear adaptive model of the OHC employing both mechanisms of the mechanical activity. The modeling results show that the high sensitivity and frequency selectivity of the filtering system of the cochlea depend on the somatic motility of the OHC. However, both mechanisms of mechanical activity are involved in the adaptation to sound intensity and efferent-synaptic influence. The fast (alternating) component (AC) of the mechanical–electrical transduction signal controls the motor protein prestin and fast changes in axial length of the cell. The slow (direct) component (DC) appearing at high signal intensity affects the axial stiffness, the cell length and the position of the hair bundle. The efferent influence is realized by the same mechanism.
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| 6. |
- Stasiunas, Antanas, et al.
(författare)
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An adaptive panoramic filter bank as a qualitative model of the filtering system of the cochlea : The peculiarities in linear and nonlinear mode
- 2012
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Ingår i: Medical Engineering and Physics. - Oxford : Elsevier. - 1350-4533 .- 1873-4030. ; 34:2, s. 187-194
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Tidskriftsartikel (refereegranskat)abstract
- Outer hair cells in the cochlea of the ear, together with the local structures of the basilar membrane, reticular lamina and tectorial membrane constitute the adaptive primary filters (PF) of the second order. We used them for designing a serial-parallel signal filtering system. We determined a rational number of the PF included in Gaussian channels of the system, summation weights of the output signals, and distribution of the PF along the basilar membrane. A Gaussian panoramic filter bank each channel of which consists of five PF is presented as an example. The properties of the PF, the channel and the filter bank operating in the linear and nonlinear modes are determined during adaptation and under efferent control. The results suggest that application of biological filtering principles can be useful for designing cochlear implants with new speech encoding strategies. © 2011 IPEM.
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| 7. |
- Stasiunas, Antanas, et al.
(författare)
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Compression, adaptation and efferent control in a revised outer hair cell functional model
- 2005
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Ingår i: Medical Engineering and Physics. - Amsterdam : Elsevier. - 1350-4533 .- 1873-4030. ; 27:9, s. 780-789
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Tidskriftsartikel (refereegranskat)abstract
- In the cochlea of the inner ear, outer hair cells (OHC) together with the local passive structures of the tectorial and basilar membranes comprise non-linear resonance circuits with the local and central (afferent–efferent) feedback. The characteristics of these circuits and their control possibilities depend on the mechanomotility of the OHC. The main element of our functional model of the OHC is the mechanomotility circuit with the general transfer characteristic y = k tanh(x − a). The parameter k of this characteristic reflects the axial stiffness of the OHC, and the parameter a working position of the hair bundle. The efferent synaptic signals act on the parameter k directly and on the parameter a indirectly through changes in the membrane potential. The dependences of the sensitivity and selectivity on changes in the parameters a and k are obtained by the computer simulation. Functioning of the model at low-level input signals is linear. Due to the non-linearity of the transfer characteristic of the mechanomotility circuit the high-level signals are compressed. For the adaptation and efferent control, however, the transfer characteristic with respect to the initial operating point should be asymmetrical (a > 0). The asymmetry relies on the deflection of the hair bundle from the axis of the OHC.
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| 8. |
- Stasiunas, Antanas, et al.
(författare)
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Physiologically inspired signal preprocessing for auditory prostheses : Insights from the electro-motility of the OHC
- 2008
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Ingår i: Medical Engineering and Physics. - Oxford, England : Elsevier. - 1350-4533 .- 1873-4030. ; 30:2, s. 171-181
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Tidskriftsartikel (refereegranskat)abstract
- We designed a non-linear functional model of the outer hair cell (OHC) functioning in the filtering system of the cochlea and then isolated from it two second-order structures, one employing the mechanism of the somatic motility and the other the hair bundle motion of the OHC. The investigation of these circuits showed that the main mechanism increasing the sensitivity and frequency selectivity of the filtering system is the somatic motility. The mechanism of the active hair bundle motion appeared less suitable for realization of the band-pass filtering structures due to the dependence of the sensitivity, natural frequency and selectivity on the signal intensity. We combined three second-order filtering structures employing the mechanism of the somatic motility and the lateral inhibition to form a parallel-type filtering channel of the sixth order with the frequency characteristics of the Butterworth-type and Gaussian-type. The investigation of these channels showed that the Gaussian-type channel has the advantage over the Butterworth-type channel. It is more suitable for realization of a filter bank with common lateral circuits and has less distorted frequency characteristic in the nonlinear mode.
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| 9. |
- Alzghoul, Ahmad, et al.
(författare)
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Screening paper runnability in a web-offset pressroom by data mining
- 2009
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Ingår i: Proceedings of the 9th Industrial Conference on Advances in Data Mining. - Berlin : Springer Berlin/Heidelberg. - 9783642030666 ; , s. 161-175
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Konferensbidrag (refereegranskat)abstract
- This paper is concerned with data mining techniques for identifying the main parameters of the printing press, the printing process and paper affecting the occurrence of paper web breaks in a pressroom.Two approaches are explored. The first one treats the problem as a task of data classification into “break” and “non break” classes. The procedures of classifier design and selection of relevant input variables are integrated into one process based on genetic search. The search process results in a set of input variables providing the lowest average loss incurred in taking decisions. The second approach, also based on genetic search, combines procedures of input variable selection and data mapping into a low dimensional space. The tests have shown that the web tension parameters are amongst the most important ones. It was also found that, provided the basic off-line paper parameters are in an acceptable range, the paper related parameters recorded online contain more information for predicting the occurrence of web breaks than the off-line ones. Using the selected set of parameters, on average, 93.7% of the test set data were classified correctly. The average classification accuracy of the break cases was equal to 76.7%.
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| 10. |
- Bacauskiene, Marija, et al.
(författare)
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A feature selection technique for generation of classification committees and its application to categorization of laryngeal images
- 2009
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Ingår i: Pattern Recognition. - New York : Pergamon Press. - 0031-3203 .- 1873-5142. ; 42:5, s. 645-654
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Tidskriftsartikel (refereegranskat)abstract
- This paper is concerned with a two phase procedure to select salient features (variables) for classification committees. Both filter and wrapper approaches to feature selection are combined in this work. In the first phase, definitely redundant features are eliminated based on the paired t-test. The test compares the saliency of the candidate and the noise features. In the second phase, the genetic search is employed. The search integrates the steps of training, aggregation of committee members, selection of hyper-parameters, and selection of salient features into the same learning process. A small number of genetic iterations needed to find a solution is the characteristic feature of the genetic search procedure developed. The experimental tests performed on five real-world problems have shown that significant improvements in Classification accuracy can be obtained in a small number of iterations if compared to the case of using all the features available.
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