Pub Date : 2002-11-07DOI: 10.1109/ICDSP.2002.1028300
L. Moraru, L. Cimponeriu, Anastasios Bezerianos
The present work proposes an optimal symbol dynamics transformation as an approach to analyze dynamic aspects of heart rate variability (HRV) in an asphyxia experiment in rats. The approximate entropy (ApEn) was used to quantify the regularity of short symbolic sequences derived from 5 min R-R intervals (RRI). The comparison of several symbol transformations applied in HRV analysis indicates our approach as optimal for characterizing the transitions between different phases in the recovery process following asphyxia in rats.
本文提出了一种最优符号动态变换方法来分析大鼠窒息实验中心率变异性(HRV)的动态方面。利用近似熵(ApEn)来量化由5 min R-R区间(RRI)得到的短符号序列的规律性。在HRV分析中应用的几种符号变换的比较表明，我们的方法是表征大鼠窒息后恢复过程中不同阶段之间转换的最佳方法。
{"title":"Heart period dynamics following an asphyxia experiment in rats","authors":"L. Moraru, L. Cimponeriu, Anastasios Bezerianos","doi":"10.1109/ICDSP.2002.1028300","DOIUrl":"https://doi.org/10.1109/ICDSP.2002.1028300","url":null,"abstract":"The present work proposes an optimal symbol dynamics transformation as an approach to analyze dynamic aspects of heart rate variability (HRV) in an asphyxia experiment in rats. The approximate entropy (ApEn) was used to quantify the regularity of short symbolic sequences derived from 5 min R-R intervals (RRI). The comparison of several symbol transformations applied in HRV analysis indicates our approach as optimal for characterizing the transitions between different phases in the recovery process following asphyxia in rats.","PeriodicalId":351073,"journal":{"name":"2002 14th International Conference on Digital Signal Processing Proceedings. DSP 2002 (Cat. No.02TH8628)","volume":"25 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2002-11-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"116468337","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2002-11-07DOI: 10.1109/ICDSP.2002.1028264
H. Veeraraghavan, O. Masoud, N. Papanikolopoulos
The goal of this project is to develop a passive vision-based sensing system capable of monitoring an intersection by observing the vehicle and pedestrian flow, and predicting situations that might give rise to accidents. A single camera mounted at an arbitrary position looking at an intersection is used. However, for extended applications multiple cameras will be needed. Some of the key elements are camera calibration, motion tracking, vehicle classification, and predicting collisions. In this paper, we focus on motion tracking. Motion segmentation is performed using an adaptive background model that models each pixel as a mixture of Gaussians. The method used is similar to the Stauffer method for motion segmentation. Tracking of objects is performed by computing the overlap between oriented bounding boxes. The oriented boxes are computed by vector quantization of blobs in the scene. The principal angles computed during vector quantization along with other cues of the object are used for classification of detected entities into vehicles and pedestrians.
{"title":"Real-time tracking for managing suburban intersections","authors":"H. Veeraraghavan, O. Masoud, N. Papanikolopoulos","doi":"10.1109/ICDSP.2002.1028264","DOIUrl":"https://doi.org/10.1109/ICDSP.2002.1028264","url":null,"abstract":"The goal of this project is to develop a passive vision-based sensing system capable of monitoring an intersection by observing the vehicle and pedestrian flow, and predicting situations that might give rise to accidents. A single camera mounted at an arbitrary position looking at an intersection is used. However, for extended applications multiple cameras will be needed. Some of the key elements are camera calibration, motion tracking, vehicle classification, and predicting collisions. In this paper, we focus on motion tracking. Motion segmentation is performed using an adaptive background model that models each pixel as a mixture of Gaussians. The method used is similar to the Stauffer method for motion segmentation. Tracking of objects is performed by computing the overlap between oriented bounding boxes. The oriented boxes are computed by vector quantization of blobs in the scene. The principal angles computed during vector quantization along with other cues of the object are used for classification of detected entities into vehicles and pedestrians.","PeriodicalId":351073,"journal":{"name":"2002 14th International Conference on Digital Signal Processing Proceedings. DSP 2002 (Cat. No.02TH8628)","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2002-11-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"125952115","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2002-11-07DOI: 10.1109/ICDSP.2002.1028142
A. López, R. Molina, A. Katsaggelos
In this work we develop a Bayesian reconstruction method for SPECT (single photon emission computed tomography) images, using as prior GGMRF (generalized Gaussian Markov random fields) distributions and estimating the scale hyperparameter following the evidence analysis. Preconditioning methods are used to estimate this hyperparameter and the approximations used are compared on synthetic images.
{"title":"Scale hyperparameter estimation for GGMRF prior models with application to SPECT images","authors":"A. López, R. Molina, A. Katsaggelos","doi":"10.1109/ICDSP.2002.1028142","DOIUrl":"https://doi.org/10.1109/ICDSP.2002.1028142","url":null,"abstract":"In this work we develop a Bayesian reconstruction method for SPECT (single photon emission computed tomography) images, using as prior GGMRF (generalized Gaussian Markov random fields) distributions and estimating the scale hyperparameter following the evidence analysis. Preconditioning methods are used to estimate this hyperparameter and the approximations used are compared on synthetic images.","PeriodicalId":351073,"journal":{"name":"2002 14th International Conference on Digital Signal Processing Proceedings. DSP 2002 (Cat. No.02TH8628)","volume":"5 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2002-11-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127712403","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2002-11-07DOI: 10.1109/ICDSP.2002.1028179
V. Nascimento
Despite its qualities of robustness, low cost, and good tracking performance, in many situations the LMS algorithm suffers from slow initial convergence. We propose a method to speed up this convergence rate by varying the length of the adaptive filter, taking advantage of the larger step-sizes allowed for short filters. The results presented here show that variable-length adaptive filters have the potential to achieve quite fast convergence rates, with a modest increase in the computational complexity.
{"title":"Improving the initial convergence of adaptive filters: variable-length LMS algorithms","authors":"V. Nascimento","doi":"10.1109/ICDSP.2002.1028179","DOIUrl":"https://doi.org/10.1109/ICDSP.2002.1028179","url":null,"abstract":"Despite its qualities of robustness, low cost, and good tracking performance, in many situations the LMS algorithm suffers from slow initial convergence. We propose a method to speed up this convergence rate by varying the length of the adaptive filter, taking advantage of the larger step-sizes allowed for short filters. The results presented here show that variable-length adaptive filters have the potential to achieve quite fast convergence rates, with a modest increase in the computational complexity.","PeriodicalId":351073,"journal":{"name":"2002 14th International Conference on Digital Signal Processing Proceedings. DSP 2002 (Cat. No.02TH8628)","volume":"2 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2002-11-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"128804912","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2002-11-07DOI: 10.1109/ICDSP.2002.1028222
Anwar S. Dawood, S. J. Visser, John A. Williams
Programmable logic offers an efficient solution for the performance and flexibility required by real time image processing systems. Application specific integrated circuit (ASIC) devices could provide such performance, but the lack of flexibility for changing operation requirements and the associated high development and production cost limit their acceptance for space applications. Field programmable gate arrays (FPGAs) offer highly flexible designs, scalable circuits, and real time system performance. The parallel processing power of FPGAs allows data to be processed more quickly than a similar microprocessor implementation. The High Performance Computing (HPC-I) payload for the Australian scientific mission satellite FedSat has been designed and manufactured to validate the use of FPGA technology onboard satellites for a variety of space applications. This paper elaborates on implementing image processing algorithms and techniques on FPGAs for space applications. It presents the implementation, testing and performance evaluation of a Gaussian filter and convolution engine on HPC-I.
{"title":"Reconfigurable FPGAS for real time image processing in space","authors":"Anwar S. Dawood, S. J. Visser, John A. Williams","doi":"10.1109/ICDSP.2002.1028222","DOIUrl":"https://doi.org/10.1109/ICDSP.2002.1028222","url":null,"abstract":"Programmable logic offers an efficient solution for the performance and flexibility required by real time image processing systems. Application specific integrated circuit (ASIC) devices could provide such performance, but the lack of flexibility for changing operation requirements and the associated high development and production cost limit their acceptance for space applications. Field programmable gate arrays (FPGAs) offer highly flexible designs, scalable circuits, and real time system performance. The parallel processing power of FPGAs allows data to be processed more quickly than a similar microprocessor implementation. The High Performance Computing (HPC-I) payload for the Australian scientific mission satellite FedSat has been designed and manufactured to validate the use of FPGA technology onboard satellites for a variety of space applications. This paper elaborates on implementing image processing algorithms and techniques on FPGAs for space applications. It presents the implementation, testing and performance evaluation of a Gaussian filter and convolution engine on HPC-I.","PeriodicalId":351073,"journal":{"name":"2002 14th International Conference on Digital Signal Processing Proceedings. DSP 2002 (Cat. No.02TH8628)","volume":"2 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2002-11-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"129049904","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2002-11-07DOI: 10.1109/ICDSP.2002.1028345
M. Beddoes, R. Ward
This paper proposes a hybrid of two methods to determine the weight-constants in a class of artificial neuron networks, ANNs. The class of ANNs we are interested in are characterized by feed-forward processing elements. One of the methods is the genetic algorithm, GA; the other is "training through" back-propagation of the error, BPE. We expect our hybrid scheme to be faster than using BPE alone.
{"title":"A possible genetic-algorithm based method for optimizing a class of ANN transfer functions","authors":"M. Beddoes, R. Ward","doi":"10.1109/ICDSP.2002.1028345","DOIUrl":"https://doi.org/10.1109/ICDSP.2002.1028345","url":null,"abstract":"This paper proposes a hybrid of two methods to determine the weight-constants in a class of artificial neuron networks, ANNs. The class of ANNs we are interested in are characterized by feed-forward processing elements. One of the methods is the genetic algorithm, GA; the other is \"training through\" back-propagation of the error, BPE. We expect our hybrid scheme to be faster than using BPE alone.","PeriodicalId":351073,"journal":{"name":"2002 14th International Conference on Digital Signal Processing Proceedings. DSP 2002 (Cat. No.02TH8628)","volume":"2 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2002-11-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130412978","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2002-11-07DOI: 10.1109/ICDSP.2002.1028202
Christos Papathanassiou, M. Petrou
We propose the modification of the cost function that is optimised by the independent component analysis (ICA) algorithm, so that prior knowledge about some statistical properties of one of the components is incorporated in the optimisation process, for this component to be identified first. Once this component is removed from the recordings, the remaining components may be identified in the usual way. We demonstrate our idea using simulated data, for which the true mixing coefficients are known. We show that the incorporation of the constraint broadens the region around the true mixing values over which, if we start the algorithm, it will converge to the desired solution.
{"title":"Incorporating prior knowledge in ICA","authors":"Christos Papathanassiou, M. Petrou","doi":"10.1109/ICDSP.2002.1028202","DOIUrl":"https://doi.org/10.1109/ICDSP.2002.1028202","url":null,"abstract":"We propose the modification of the cost function that is optimised by the independent component analysis (ICA) algorithm, so that prior knowledge about some statistical properties of one of the components is incorporated in the optimisation process, for this component to be identified first. Once this component is removed from the recordings, the remaining components may be identified in the usual way. We demonstrate our idea using simulated data, for which the true mixing coefficients are known. We show that the incorporation of the constraint broadens the region around the true mixing values over which, if we start the algorithm, it will converge to the desired solution.","PeriodicalId":351073,"journal":{"name":"2002 14th International Conference on Digital Signal Processing Proceedings. DSP 2002 (Cat. No.02TH8628)","volume":"12 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2002-11-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131448505","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2002-11-07DOI: 10.1109/ICDSP.2002.1028204
Roberto López-Valcarce
The channel equalization problem for staggered (or offset) modulation formats is considered. It is shown that, due to the relative time offset of the in-phase and quadrature components, the received signal must be sampled at twice the baud rate of the corresponding non-staggered signal. This suggests that perfect zero-forcing equalization may be achievable as in standard fractionally sampled systems. To explore this feature, the MMSE linear equalizer (LE), which turns out to be a periodically time-varying filter, is obtained. It is shown that the MMSE LE can be implemented with an LTI (linear time invariant) filter and a set of periodic switches and modulators. Using this, necessary conditions for zero-forcing equalization with FIR filters are derived.
{"title":"Channel equalization with staggered modulation formats","authors":"Roberto López-Valcarce","doi":"10.1109/ICDSP.2002.1028204","DOIUrl":"https://doi.org/10.1109/ICDSP.2002.1028204","url":null,"abstract":"The channel equalization problem for staggered (or offset) modulation formats is considered. It is shown that, due to the relative time offset of the in-phase and quadrature components, the received signal must be sampled at twice the baud rate of the corresponding non-staggered signal. This suggests that perfect zero-forcing equalization may be achievable as in standard fractionally sampled systems. To explore this feature, the MMSE linear equalizer (LE), which turns out to be a periodically time-varying filter, is obtained. It is shown that the MMSE LE can be implemented with an LTI (linear time invariant) filter and a set of periodic switches and modulators. Using this, necessary conditions for zero-forcing equalization with FIR filters are derived.","PeriodicalId":351073,"journal":{"name":"2002 14th International Conference on Digital Signal Processing Proceedings. DSP 2002 (Cat. No.02TH8628)","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2002-11-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132096270","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2002-11-07DOI: 10.1109/ICDSP.2002.1028136
S. Chan, K. Pun, K. Ho
This paper proposes two new methods for designing a class of 2-channel PR FlR filterbanks and wavelets with Kregularity of high order. The K-regularity constraints are expressed as a set of linear constraints in the design variables. The first method formulates the design problem as a quadratic programming problem with linear equality constraints (QPLC), which can be solved using the method of Lagrange multiplier. The second design method employs the minimax error criteria and solves the design problem as a semidefinite programming problem (SDP). By removing the redundant variablcs, the equality constraints are automatically imposed into the design problem. The optimization problem is then formulated as a linear convex objective function subject to a union of affine set which can be represented by a set of linear matrix inequalities. Hence they can be solved using existing SDP solver. Design examples are given to demonstrate the effectiveness of the proposed methods.
{"title":"The design of a class of prefect reconstruction two-channel FIR and wavelets filterbanks using constrained least squares method and semidefinite programming","authors":"S. Chan, K. Pun, K. Ho","doi":"10.1109/ICDSP.2002.1028136","DOIUrl":"https://doi.org/10.1109/ICDSP.2002.1028136","url":null,"abstract":"This paper proposes two new methods for designing a class of 2-channel PR FlR filterbanks and wavelets with Kregularity of high order. The K-regularity constraints are expressed as a set of linear constraints in the design variables. The first method formulates the design problem as a quadratic programming problem with linear equality constraints (QPLC), which can be solved using the method of Lagrange multiplier. The second design method employs the minimax error criteria and solves the design problem as a semidefinite programming problem (SDP). By removing the redundant variablcs, the equality constraints are automatically imposed into the design problem. The optimization problem is then formulated as a linear convex objective function subject to a union of affine set which can be represented by a set of linear matrix inequalities. Hence they can be solved using existing SDP solver. Design examples are given to demonstrate the effectiveness of the proposed methods.","PeriodicalId":351073,"journal":{"name":"2002 14th International Conference on Digital Signal Processing Proceedings. DSP 2002 (Cat. No.02TH8628)","volume":"1 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2002-11-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"132097062","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Pub Date : 2002-11-07DOI: 10.1109/ICDSP.2002.1028270
I. Dokas, V. Tsagaris, V. Anastassopoulos
Higher order spectral properties of /spl Sigma/-/spl Delta/ sequences are studied. For this purpose a first-order single stage /spl Sigma/-/spl Delta/ modulator is considered having as input a pure sinusoid. The nonlinear behavior of the /spl Sigma/-/spl Delta/ modulator is examined by means of the bispectrum and the bicoherence. These functions reveal the statistical properties of the quantization noise, its dependence on the signal as well as the phase coupling between the signal and the noise. The quantizer and the integrator of the /spl Sigma/-/spl Delta/ modulator have been studied, using different functions, to simulate the deviations from the ideal behavior.
{"title":"Higher order spectral analysis of nonlinear behavior in /spl Sigma/-/spl Delta/ modulator","authors":"I. Dokas, V. Tsagaris, V. Anastassopoulos","doi":"10.1109/ICDSP.2002.1028270","DOIUrl":"https://doi.org/10.1109/ICDSP.2002.1028270","url":null,"abstract":"Higher order spectral properties of /spl Sigma/-/spl Delta/ sequences are studied. For this purpose a first-order single stage /spl Sigma/-/spl Delta/ modulator is considered having as input a pure sinusoid. The nonlinear behavior of the /spl Sigma/-/spl Delta/ modulator is examined by means of the bispectrum and the bicoherence. These functions reveal the statistical properties of the quantization noise, its dependence on the signal as well as the phase coupling between the signal and the noise. The quantizer and the integrator of the /spl Sigma/-/spl Delta/ modulator have been studied, using different functions, to simulate the deviations from the ideal behavior.","PeriodicalId":351073,"journal":{"name":"2002 14th International Conference on Digital Signal Processing Proceedings. DSP 2002 (Cat. No.02TH8628)","volume":"16 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"2002-11-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"133824905","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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