David Colella - Academia.edu (original) (raw)

Papers by David Colella

This paper discusses the observation and interpretation of chirp-like striation patterns in proce... more This paper discusses the observation and interpretation of chirp-like striation patterns in processed spectrograms of single channel electrocorticograms associated with epileptic patients. A pulse amplitude modulation model is presented as a possible mechanism for the appearance of the chirp-like patterns.<<ETX>>

: A subcommittee of the Test, Evaluation, and Assessment Support Group was formed to address issu... more : A subcommittee of the Test, Evaluation, and Assessment Support Group was formed to address issues and procedures relating to the Advanced Processor Build Step 3 test and analysis procedures. This examination was prompted by the recent APB-99 Step 4 test, wherein a number of system deficiencies were noted with little or no perceived forewarning from the APB-99 Step 3 evaluation. This report discusses the subcommittee's assessment of the overall Step 3 process and its implementation. The report provides conclusions regarding the implementation of the APB Step 3 mechanism and recommendations for the modification of Step 3 procedures so that more effective functional and integrated system testing can be attained. The failure to adequately address the Step 3 procedural issues raised here can increase performance risk associated with each new generation APB sonar system build. A majority of the system deficiencies highlighted during the APB-99 Step 4 sea test were either observed du...

The past ten years have seen an explosion of research in the theory of wavelets and their applica... more The past ten years have seen an explosion of research in the theory of wavelets and their applications. Theoretical accomplishments include development of new bases for many different function spaces and the characterization of orthonormal wavelets with compact support. Applications span the fields of signal processing, image processing and compression, data compression, and quantum mechanics. At the present time however, much of the literature remains highly mathematical, and consequently, a large investment of time is often necessary to develop a general understanding of wavelets and their potential uses. This paper thus seeks to provide an overview of the wavelet transform from an intuitive standpoint. Throughout the paper a signal processing frame of reference is adopted.

MATHEMATICA SCANDINAVICA, 1988

This paper examines the beam-based minimum variance soft constraint beamformer and shows that the... more This paper examines the beam-based minimum variance soft constraint beamformer and shows that the beamformer array gain is almost always a function of SNR. The analysis shows that the MVSC array gain is necessarily a nonincreasing function of SNR and, in fact, is either strictly decreasing or constant relative to SNR. This result supplements earlier results of Van Veen and helps explain behavior observed in processed data.

This report completes the Consumer Reports performance analysis study for the Phase 1 Advanced Pr... more This report completes the Consumer Reports performance analysis study for the Phase 1 Advanced Processor Build sonar system. It provides a performance comparison between the conventional beamformer and the beam-based minimum variance soft constraint adaptive beamformer processing modules. Comparison was based on a beam noise output metric defined in terms of the beamformer array gain. This provides a more realistic measure of beamformer performance since, unlike the common definition of beam noise based solely on the noise field input to the beamformer, our beam noise metric factors in changes of signal power as the target signal is passed through the beamformer. Our results indicate that performance gain can be realized for the adaptive beamformer for certain scenarios. These gains were most likely to occur at the medium frequencies between 100 and 200 Hz, while significant gain was only occasionally observed at other frequencies. Adaptive beamforming was particularly successful when a clutter signal was present. However, any performance advantage usually begins to disappear as the target signal-to-noise ratio increases above approximately –15 dB.

Proceedings of 17th International Conference of the Engineering in Medicine and Biology Society

This paper briefly reviews MITRE's research program in ECoG-based seizure detection, classif... more This paper briefly reviews MITRE's research program in ECoG-based seizure detection, classification, localization, and waveform extrapolation, a number of signal processing algorithms are described, compared, and contrasted. This research has been performed in collaboration with The Children's National Medical Center in Washington, DC

[1991 Proceedings] IEEE Conference on Neural Networks for Ocean Engineering

ABSTRACT The authors examine the connection between training period and detection performance by ... more ABSTRACT The authors examine the connection between training period and detection performance by showing that a network can be described by a Fokker-Planck statistical model. Closed-form expressions are derived for the weight probabilities under suitable assumptions on the weight adaptivity and the noise process. Output node statistics are determined by computing the conditional output density as a function of the input statistics and averaging over the weight probabilities for a specific training time. It is shown that the training period is dominated by the time required to stabilize the bias weight. This weight is analogous to an adaptive threshold and is related directly to the network false alarm probability. A second issue addressed is the steady-state performance of the network. Explicit expressions are derived for the false alarm and detection probabilities. The authors show that the network implements a classical mini-max best

Annual International Conference of the IEEE Engineering in Medicine and Biology Society, 1995

Discusses the use of a common signal-processing tool, the spectrogram, in the detection and local... more Discusses the use of a common signal-processing tool, the spectrogram, in the detection and localization of epileptic seizures. Spectrograms are computed from electrocorticograms (ECoG) obtained by measuring electric potentials directly on the surface of the brain. Chirp-like patterns are observed in spectrograms of single-channel ECoG recordings during seizure activity which appear unique for each patient. Detection and localization of epileptic

2008 IEEE Conference on Technologies for Homeland Security, 2008

... Michael Tierney, Samar K. Guharay, David Colella, Garry Jacyna, Philip Barry ... Valuable dis... more ... Michael Tierney, Samar K. Guharay, David Colella, Garry Jacyna, Philip Barry ... Valuable discussions with Gerardo Garcia and Rick Micker of The MITRE Corporation, scientists from the Pacific Northwest National Laboratory, especially with Nicholas Lombardo and Gregory Holter ...

Proceedings. The First IEEE Regional Conference on Aerospace Control Systems,

The modeling 1/f processes using wavelet expansions is applied to a detection and receiver design... more The modeling 1/f processes using wavelet expansions is applied to a detection and receiver design problem forv a signal with known envelope and random phase corrupted by 1/f noise.

SPIE Proceedings, 1995

A wavelet-based technique WISP is used to discriminate normal brain activity from brain activity ... more A wavelet-based technique WISP is used to discriminate normal brain activity from brain activity during epileptic seizures. The WISP technique is used to exploit the noted difference in frequency content during the normal brain state and the seizure brain state so that detection and localization decisions can be made. An AR-Pole statistic technique is used as a comparative measure to base-line the WISP performance.

SPIE Proceedings, 1995

A redundant wavelet filtering method is used in conjunction with spectrogram computations to addr... more A redundant wavelet filtering method is used in conjunction with spectrogram computations to address a component of the problem of predicting epileptic seizure activity. It is shown that spectrograms of seizure episodes exhibit multiple chirps consistent with the relatively simple almost ...

Contemporary Mathematics, 1989

Electroencephalography and Clinical Neurophysiology, 1997

Proceedings of the American Mathematical Society, 1983

The existence of a Helson set disobeying spectral synthesis is combined with the modified Herz cr... more The existence of a Helson set disobeying spectral synthesis is combined with the modified Herz criterion to construct a subset E of the circle such that spectral synthesis holds for E and fails for dE.

Clinical Neurophysiology, 2000

Objective: A chirp is a brief signal within which the frequency content changes rapidly. Spectrog... more Objective: A chirp is a brief signal within which the frequency content changes rapidly. Spectrographic chirps are found in signals produced from many biological and physical phenomena. In radar and sonar engineering, signals with chirps are used to localize direction and range to the signal source. Although characteristic frequency changes during epileptic seizures have long been observed, the correlation with chirps and chirp technology seems never to have been made. Methods: We analyzed 19 404 s (1870 s of which were from 43 seizures) of intracranially (subdural and depth electrode) recorded digital EEG from 6 patients for the presence of spectral chirps. Matched ®lters were constructed from methods in routine use in non-medical signal processing applications. Results: We found that chirps are very sensitive detectors of seizures (83%), and highly speci®c as markers (no false positive detections). The feasibility of using spectral chirps as matched ®lters was demonstrated. Conclusions: Chirps are highly speci®c and sensitive spectrographic signatures of epileptic seizure activity. In addition, chirps may serve as templates for matched ®lter design to detect seizures, and as such, can demonstrate localization and propagation of seizures from an epileptic focus.

... and general relativity, James A. Isenberg, Editor 72 Fixed point theory and its applications,... more ... and general relativity, James A. Isenberg, Editor 72 Fixed point theory and its applications, RF Brown, Editor 73 Geometry of random motion, Rick Durrett and Mark A. Pinsky, Editors 74 ... chun, and Pan Chengbiao, Editors 78 Braids, Joan S. Birman and Anatoly Libgober. ...

Journal of Fourier Analysis and Applications, 1996

ABSTRACT. Matrix re nement equations are functional equations of the form f(x) = PN k=0 ck f(2x ?... more ABSTRACT. Matrix re nement equations are functional equations of the form f(x) = PN k=0 ck f(2x ? k), where the coe cients ck are matrices and f is a vector-valued function. Re nement equations play key roles in wavelet theory and approximation theory. Existence and uniqueness ...

This paper discusses the observation and interpretation of chirp-like striation patterns in proce... more This paper discusses the observation and interpretation of chirp-like striation patterns in processed spectrograms of single channel electrocorticograms associated with epileptic patients. A pulse amplitude modulation model is presented as a possible mechanism for the appearance of the chirp-like patterns.<<ETX>>

: A subcommittee of the Test, Evaluation, and Assessment Support Group was formed to address issu... more : A subcommittee of the Test, Evaluation, and Assessment Support Group was formed to address issues and procedures relating to the Advanced Processor Build Step 3 test and analysis procedures. This examination was prompted by the recent APB-99 Step 4 test, wherein a number of system deficiencies were noted with little or no perceived forewarning from the APB-99 Step 3 evaluation. This report discusses the subcommittee's assessment of the overall Step 3 process and its implementation. The report provides conclusions regarding the implementation of the APB Step 3 mechanism and recommendations for the modification of Step 3 procedures so that more effective functional and integrated system testing can be attained. The failure to adequately address the Step 3 procedural issues raised here can increase performance risk associated with each new generation APB sonar system build. A majority of the system deficiencies highlighted during the APB-99 Step 4 sea test were either observed du...

The past ten years have seen an explosion of research in the theory of wavelets and their applica... more The past ten years have seen an explosion of research in the theory of wavelets and their applications. Theoretical accomplishments include development of new bases for many different function spaces and the characterization of orthonormal wavelets with compact support. Applications span the fields of signal processing, image processing and compression, data compression, and quantum mechanics. At the present time however, much of the literature remains highly mathematical, and consequently, a large investment of time is often necessary to develop a general understanding of wavelets and their potential uses. This paper thus seeks to provide an overview of the wavelet transform from an intuitive standpoint. Throughout the paper a signal processing frame of reference is adopted.

MATHEMATICA SCANDINAVICA, 1988

This paper examines the beam-based minimum variance soft constraint beamformer and shows that the... more This paper examines the beam-based minimum variance soft constraint beamformer and shows that the beamformer array gain is almost always a function of SNR. The analysis shows that the MVSC array gain is necessarily a nonincreasing function of SNR and, in fact, is either strictly decreasing or constant relative to SNR. This result supplements earlier results of Van Veen and helps explain behavior observed in processed data.

This report completes the Consumer Reports performance analysis study for the Phase 1 Advanced Pr... more This report completes the Consumer Reports performance analysis study for the Phase 1 Advanced Processor Build sonar system. It provides a performance comparison between the conventional beamformer and the beam-based minimum variance soft constraint adaptive beamformer processing modules. Comparison was based on a beam noise output metric defined in terms of the beamformer array gain. This provides a more realistic measure of beamformer performance since, unlike the common definition of beam noise based solely on the noise field input to the beamformer, our beam noise metric factors in changes of signal power as the target signal is passed through the beamformer. Our results indicate that performance gain can be realized for the adaptive beamformer for certain scenarios. These gains were most likely to occur at the medium frequencies between 100 and 200 Hz, while significant gain was only occasionally observed at other frequencies. Adaptive beamforming was particularly successful when a clutter signal was present. However, any performance advantage usually begins to disappear as the target signal-to-noise ratio increases above approximately –15 dB.

Proceedings of 17th International Conference of the Engineering in Medicine and Biology Society

This paper briefly reviews MITRE's research program in ECoG-based seizure detection, classif... more This paper briefly reviews MITRE's research program in ECoG-based seizure detection, classification, localization, and waveform extrapolation, a number of signal processing algorithms are described, compared, and contrasted. This research has been performed in collaboration with The Children's National Medical Center in Washington, DC

[1991 Proceedings] IEEE Conference on Neural Networks for Ocean Engineering

ABSTRACT The authors examine the connection between training period and detection performance by ... more ABSTRACT The authors examine the connection between training period and detection performance by showing that a network can be described by a Fokker-Planck statistical model. Closed-form expressions are derived for the weight probabilities under suitable assumptions on the weight adaptivity and the noise process. Output node statistics are determined by computing the conditional output density as a function of the input statistics and averaging over the weight probabilities for a specific training time. It is shown that the training period is dominated by the time required to stabilize the bias weight. This weight is analogous to an adaptive threshold and is related directly to the network false alarm probability. A second issue addressed is the steady-state performance of the network. Explicit expressions are derived for the false alarm and detection probabilities. The authors show that the network implements a classical mini-max best

Annual International Conference of the IEEE Engineering in Medicine and Biology Society, 1995

Discusses the use of a common signal-processing tool, the spectrogram, in the detection and local... more Discusses the use of a common signal-processing tool, the spectrogram, in the detection and localization of epileptic seizures. Spectrograms are computed from electrocorticograms (ECoG) obtained by measuring electric potentials directly on the surface of the brain. Chirp-like patterns are observed in spectrograms of single-channel ECoG recordings during seizure activity which appear unique for each patient. Detection and localization of epileptic

2008 IEEE Conference on Technologies for Homeland Security, 2008

... Michael Tierney, Samar K. Guharay, David Colella, Garry Jacyna, Philip Barry ... Valuable dis... more ... Michael Tierney, Samar K. Guharay, David Colella, Garry Jacyna, Philip Barry ... Valuable discussions with Gerardo Garcia and Rick Micker of The MITRE Corporation, scientists from the Pacific Northwest National Laboratory, especially with Nicholas Lombardo and Gregory Holter ...

Proceedings. The First IEEE Regional Conference on Aerospace Control Systems,

The modeling 1/f processes using wavelet expansions is applied to a detection and receiver design... more The modeling 1/f processes using wavelet expansions is applied to a detection and receiver design problem forv a signal with known envelope and random phase corrupted by 1/f noise.

SPIE Proceedings, 1995

A wavelet-based technique WISP is used to discriminate normal brain activity from brain activity ... more A wavelet-based technique WISP is used to discriminate normal brain activity from brain activity during epileptic seizures. The WISP technique is used to exploit the noted difference in frequency content during the normal brain state and the seizure brain state so that detection and localization decisions can be made. An AR-Pole statistic technique is used as a comparative measure to base-line the WISP performance.

SPIE Proceedings, 1995

A redundant wavelet filtering method is used in conjunction with spectrogram computations to addr... more A redundant wavelet filtering method is used in conjunction with spectrogram computations to address a component of the problem of predicting epileptic seizure activity. It is shown that spectrograms of seizure episodes exhibit multiple chirps consistent with the relatively simple almost ...

Contemporary Mathematics, 1989

Electroencephalography and Clinical Neurophysiology, 1997

Proceedings of the American Mathematical Society, 1983

The existence of a Helson set disobeying spectral synthesis is combined with the modified Herz cr... more The existence of a Helson set disobeying spectral synthesis is combined with the modified Herz criterion to construct a subset E of the circle such that spectral synthesis holds for E and fails for dE.

Clinical Neurophysiology, 2000

Objective: A chirp is a brief signal within which the frequency content changes rapidly. Spectrog... more Objective: A chirp is a brief signal within which the frequency content changes rapidly. Spectrographic chirps are found in signals produced from many biological and physical phenomena. In radar and sonar engineering, signals with chirps are used to localize direction and range to the signal source. Although characteristic frequency changes during epileptic seizures have long been observed, the correlation with chirps and chirp technology seems never to have been made. Methods: We analyzed 19 404 s (1870 s of which were from 43 seizures) of intracranially (subdural and depth electrode) recorded digital EEG from 6 patients for the presence of spectral chirps. Matched ®lters were constructed from methods in routine use in non-medical signal processing applications. Results: We found that chirps are very sensitive detectors of seizures (83%), and highly speci®c as markers (no false positive detections). The feasibility of using spectral chirps as matched ®lters was demonstrated. Conclusions: Chirps are highly speci®c and sensitive spectrographic signatures of epileptic seizure activity. In addition, chirps may serve as templates for matched ®lter design to detect seizures, and as such, can demonstrate localization and propagation of seizures from an epileptic focus.

... and general relativity, James A. Isenberg, Editor 72 Fixed point theory and its applications,... more ... and general relativity, James A. Isenberg, Editor 72 Fixed point theory and its applications, RF Brown, Editor 73 Geometry of random motion, Rick Durrett and Mark A. Pinsky, Editors 74 ... chun, and Pan Chengbiao, Editors 78 Braids, Joan S. Birman and Anatoly Libgober. ...

Journal of Fourier Analysis and Applications, 1996

ABSTRACT. Matrix re nement equations are functional equations of the form f(x) = PN k=0 ck f(2x ?... more ABSTRACT. Matrix re nement equations are functional equations of the form f(x) = PN k=0 ck f(2x ? k), where the coe cients ck are matrices and f is a vector-valued function. Re nement equations play key roles in wavelet theory and approximation theory. Existence and uniqueness ...