Aln Fred | Instituto Superior Técnico (original) (raw)

Papers by Aln Fred

Research paper thumbnail of UNVEILING INTRINSIC SIMILARITY - Application to Temporal Analysis of ECG

Proceedings of the First International Conference on Bio-inspired Systems and Signal Processing, 2008

Research paper thumbnail of CLUSTER ENSEMBLE SELECTION - Using Average Cluster Consistency

Proceedings of the International Conference on Knowledge Discovery and Information Retrieval, 2009

Research paper thumbnail of Combining Data Clusterings with Instance Level Constraints

Proceedings of the 9th International Workshop on Pattern Recognition in Information Systems, 2009

Research paper thumbnail of Classification Using High Order Dissimilarities in Non-Euclidean Spaces

Proceedings of the 1st International Conference on Pattern Recognition Applications and Methods, 2012

Research paper thumbnail of Towards a Finger Based Ecg Biometric System

Proceedings of the International Conference on Bio-inspired Systems and Signal Processing, 2011

Research paper thumbnail of User Tuned Feature Selection in Keystroke Dynamics

Proceedings of the First International Conference on Bio-inspired Systems and Signal Processing, 2008

Research paper thumbnail of ECG Biometrics: Principles and Applications

Proceedings of the International Conference on Bio-inspired Systems and Signal Processing, 2013

Research paper thumbnail of Evidence Accumulation Approach applied to EEG Analysis

Proceedings of the 2nd International Conference on Pattern Recognition Applications and Methods, 2013

Research paper thumbnail of A Biometric Identification System based on Thyroid Tissue Echo-morphology

This paper proposes a biometric system based on features extracted from the thyroid tissue access... more This paper proposes a biometric system based on features extracted from the thyroid tissue accessed through 2D ultrasound. Tissue echo-morphology, which accounts for the intensity (echogenicity), texture and structure has started to be used as a relevant parameter in a clinical setting. In this paper, features related to texture, morphology and tissue reflectivity are extracted from the ultrasound images and the most discriminant ones are selected as an input for a prototype biometric identification system. Several classifiers were tested, with the best results (90% identification rate) being achieved with the maximum a posteriori classifier. Another classifier which only takes into account the reflectivity parameter achieved a reasonable identification rate of 70%. This suggests that the acoustic impedance (reflectivity) of the tissue is a good parameter to discriminate between individuals. This paper shows the effectiveness of the proposed classification, which can be used not onl...

Research paper thumbnail of Personal Identification and Authentication based on One-lead ECG using Ziv-Merhav Cross Parsing

In this paper, we propose a new data compression based ECG biometric method for personal identifi... more In this paper, we propose a new data compression based ECG biometric method for personal identification and authentication. The ECG is an emerging biometric that does not need liveliness verification. There is strong evidence that ECG signals contain sufficient discriminative information to allow the identification of individuals from a large population. Most approaches rely on ECG data and the fiducia of different parts of the heartbeat waveform. However nonfiducial approaches have proved recently to be also effective, and have the advantage of not relying critically on the accurate extraction of fiducia. We propose a non-fiducial method based on the Ziv-Merhav cross parsing algorithm for symbol sequences (strings). Our method uses a string similarity measure obtained with a data compression algorithm. We present results on real data, one-lead ECG, acquired during a concentration task, from 19 healthy individuals, on which our approach achieves 100% subject identification rate and ...

Research paper thumbnail of Probabilistic Evidence Accumulation for Clustering Ensembles

Proceedings of the 2nd International Conference on Pattern Recognition Applications and Methods, 2013

Research paper thumbnail of Real Time Electrocardiogram Segmentation for Finger Based Ecg Biometrics

Proceedings of the International Conference on Bio-inspired Systems and Signal Processing, 2012

Research paper thumbnail of The Area under the ROC Curve as a Criterion for Clustering Evaluation

Proceedings of the 2nd International Conference on Pattern Recognition Applications and Methods, 2013

Research paper thumbnail of Exploratory EEG Analysis using Clustering and Phase-locking Factor

Proceedings of the International Conference on Bio-inspired Systems and Signal Processing, 2013

Research paper thumbnail of Experimental Apparatus for Finger Ecg Biometrics

Proceedings of the International Conference on Biomedical Electronics and Devices, 2012

Research paper thumbnail of Attributed grammars in hypnogram analysis

Systems, Man and Cybernetics, Oct 22, 1995

The hypnogram is a schematic representation of sleep dynamics as a sequence of stages along the n... more The hypnogram is a schematic representation of sleep dynamics as a sequence of stages along the night. The authors have shown, in previous work, the adequacy of syntactic modeling in automatic sleep analysis. According to this approach, the hypnogram is viewed as expression of a language whose temporal organization is described by stochastic context-free grammars. Here, the authors propose a hybrid model combining syntactic and semantic information, where stage duration is taken into account in terms of attributed grammars. This model enables hypnogram simulation, by means of language generation, and provides improvement in classification accuracy. The method is applied in automatic hypnogram analysis of a control group and a population of dysthymic patients.

Research paper thumbnail of Eigen Heartbeats for User Identification

Research paper thumbnail of Solomonoff coding as a means of introducing prior information in syntactic pattern recognition

Proceedings of the 12th IAPR International Conference on Pattern Recognition (Cat. No.94CH3440-5)

ABSTRACT

Research paper thumbnail of Improving sentence recognition in stochastic context-free grammars

Proceedings of ICASSP '94. IEEE International Conference on Acoustics, Speech and Signal Processing

ABSTRACT

Research paper thumbnail of An heuristic-based context-free parsing algorithm

IEEE International Conference on Acoustics Speech and Signal Processing, 1993

... s. ba.sed on the initia.1 st,a.te and put. it 011 a list called OPEN. 2. If OPEN is eiiipt&am... more ... s. ba.sed on the initia.1 st,a.te and put. it 011 a list called OPEN. 2. If OPEN is eiiipt'y, exit wit,li failure; ot,lierwi-se cont,inue. ... exit with t,lie solution pat,li obtaiiied by tracing t,lirough tlie poiii-t'ers, the cost. fd(n.) = 3d(n) aiid the proba-bility f, (72) = y, (71,); otherwise continue. ...

Research paper thumbnail of UNVEILING INTRINSIC SIMILARITY - Application to Temporal Analysis of ECG

Proceedings of the First International Conference on Bio-inspired Systems and Signal Processing, 2008

Research paper thumbnail of CLUSTER ENSEMBLE SELECTION - Using Average Cluster Consistency

Proceedings of the International Conference on Knowledge Discovery and Information Retrieval, 2009

Research paper thumbnail of Combining Data Clusterings with Instance Level Constraints

Proceedings of the 9th International Workshop on Pattern Recognition in Information Systems, 2009

Research paper thumbnail of Classification Using High Order Dissimilarities in Non-Euclidean Spaces

Proceedings of the 1st International Conference on Pattern Recognition Applications and Methods, 2012

Research paper thumbnail of Towards a Finger Based Ecg Biometric System

Proceedings of the International Conference on Bio-inspired Systems and Signal Processing, 2011

Research paper thumbnail of User Tuned Feature Selection in Keystroke Dynamics

Proceedings of the First International Conference on Bio-inspired Systems and Signal Processing, 2008

Research paper thumbnail of ECG Biometrics: Principles and Applications

Proceedings of the International Conference on Bio-inspired Systems and Signal Processing, 2013

Research paper thumbnail of Evidence Accumulation Approach applied to EEG Analysis

Proceedings of the 2nd International Conference on Pattern Recognition Applications and Methods, 2013

Research paper thumbnail of A Biometric Identification System based on Thyroid Tissue Echo-morphology

This paper proposes a biometric system based on features extracted from the thyroid tissue access... more This paper proposes a biometric system based on features extracted from the thyroid tissue accessed through 2D ultrasound. Tissue echo-morphology, which accounts for the intensity (echogenicity), texture and structure has started to be used as a relevant parameter in a clinical setting. In this paper, features related to texture, morphology and tissue reflectivity are extracted from the ultrasound images and the most discriminant ones are selected as an input for a prototype biometric identification system. Several classifiers were tested, with the best results (90% identification rate) being achieved with the maximum a posteriori classifier. Another classifier which only takes into account the reflectivity parameter achieved a reasonable identification rate of 70%. This suggests that the acoustic impedance (reflectivity) of the tissue is a good parameter to discriminate between individuals. This paper shows the effectiveness of the proposed classification, which can be used not onl...

Research paper thumbnail of Personal Identification and Authentication based on One-lead ECG using Ziv-Merhav Cross Parsing

In this paper, we propose a new data compression based ECG biometric method for personal identifi... more In this paper, we propose a new data compression based ECG biometric method for personal identification and authentication. The ECG is an emerging biometric that does not need liveliness verification. There is strong evidence that ECG signals contain sufficient discriminative information to allow the identification of individuals from a large population. Most approaches rely on ECG data and the fiducia of different parts of the heartbeat waveform. However nonfiducial approaches have proved recently to be also effective, and have the advantage of not relying critically on the accurate extraction of fiducia. We propose a non-fiducial method based on the Ziv-Merhav cross parsing algorithm for symbol sequences (strings). Our method uses a string similarity measure obtained with a data compression algorithm. We present results on real data, one-lead ECG, acquired during a concentration task, from 19 healthy individuals, on which our approach achieves 100% subject identification rate and ...

Research paper thumbnail of Probabilistic Evidence Accumulation for Clustering Ensembles

Proceedings of the 2nd International Conference on Pattern Recognition Applications and Methods, 2013

Research paper thumbnail of Real Time Electrocardiogram Segmentation for Finger Based Ecg Biometrics

Proceedings of the International Conference on Bio-inspired Systems and Signal Processing, 2012

Research paper thumbnail of The Area under the ROC Curve as a Criterion for Clustering Evaluation

Proceedings of the 2nd International Conference on Pattern Recognition Applications and Methods, 2013

Research paper thumbnail of Exploratory EEG Analysis using Clustering and Phase-locking Factor

Proceedings of the International Conference on Bio-inspired Systems and Signal Processing, 2013

Research paper thumbnail of Experimental Apparatus for Finger Ecg Biometrics

Proceedings of the International Conference on Biomedical Electronics and Devices, 2012

Research paper thumbnail of Attributed grammars in hypnogram analysis

Systems, Man and Cybernetics, Oct 22, 1995

The hypnogram is a schematic representation of sleep dynamics as a sequence of stages along the n... more The hypnogram is a schematic representation of sleep dynamics as a sequence of stages along the night. The authors have shown, in previous work, the adequacy of syntactic modeling in automatic sleep analysis. According to this approach, the hypnogram is viewed as expression of a language whose temporal organization is described by stochastic context-free grammars. Here, the authors propose a hybrid model combining syntactic and semantic information, where stage duration is taken into account in terms of attributed grammars. This model enables hypnogram simulation, by means of language generation, and provides improvement in classification accuracy. The method is applied in automatic hypnogram analysis of a control group and a population of dysthymic patients.

Research paper thumbnail of Eigen Heartbeats for User Identification

Research paper thumbnail of Solomonoff coding as a means of introducing prior information in syntactic pattern recognition

Proceedings of the 12th IAPR International Conference on Pattern Recognition (Cat. No.94CH3440-5)

ABSTRACT

Research paper thumbnail of Improving sentence recognition in stochastic context-free grammars

Proceedings of ICASSP '94. IEEE International Conference on Acoustics, Speech and Signal Processing

ABSTRACT

Research paper thumbnail of An heuristic-based context-free parsing algorithm

IEEE International Conference on Acoustics Speech and Signal Processing, 1993

... s. ba.sed on the initia.1 st,a.te and put. it 011 a list called OPEN. 2. If OPEN is eiiipt&am... more ... s. ba.sed on the initia.1 st,a.te and put. it 011 a list called OPEN. 2. If OPEN is eiiipt'y, exit wit,li failure; ot,lierwi-se cont,inue. ... exit with t,lie solution pat,li obtaiiied by tracing t,lirough tlie poiii-t'ers, the cost. fd(n.) = 3d(n) aiid the proba-bility f, (72) = y, (71,); otherwise continue. ...