72 research outputs found
Information Processing for Biological Signals: Application to Laser Doppler Vibrometry
Signals associated with biological activity in the human body can be of great value in clinical and security applications. Since direct measurements of critical biological activity are often difficult to acquire noninvasively, many biological signals are measured from the surface of the skin. This simplifies the signal acquisition, but complicates post processing tasks. Modeling these signals using the underlying physics may not be accurate due to the inherent complexities of the human body. The appropriate use of such models depends on the application of interest. Models developed in this dissertation are motivated by underlying physiology and physics, and are capable of expressing a wide range of signal variability without explicitly invoking physical quantities. An approach for the processing of biological signals is developed using graphical models. Graphical models describe conditional dependence between random variables on a graph. When the graph is a tree, efficient algorithms exist to compute sum-marginals or max-marginals of the joint distribution. Some of the variables correspond to the measured signal, while others may represent the hidden internal dynamics that generate the observed data. Three levels of hidden dynamics are outlined, which enable models to be constructed that track internal dynamics on differing time scales. Expectation maximization algorithms are used to compute parameter estimates. Experimental results of this approach are presented for a novel method of recording bio-mechanical activity using a Laser Doppler Vibrometer. The LDV measures surface velocity on the basis of the Doppler shift. This device is targeted on the neck overlying the carotid artery, and the proximity of the carotid to the skin results in a strong signal. Vibrations and movements from within the carotid are transmitted to the surface of the skin, where they are sensed by the LDV. Changes in the size of the carotid due to variations in blood pressure are sensed at the skin surface. In addition, breathing activity may be inferred from the LDV signal. Individualized models are evaluated systematically on LDV data sets that were acquired under resting conditions on multiple occasions. Model fit is evaluated both within and across recording sessions. Model parameters are interpreted in terms of the underlying physiology. Pressure wave physics in a series of elastic tubes is presented to explore the underlying physics of blood flow in the carotid. Mechanical movements of the carotid walls are related to the underlying pressure, and therefore the cardiovascular activity of the heart and vasculature. This analysis motivates a model that can be estimated from experimental data. Resulting models are interpreted for the LDV signal. The graphical models are applied to the problem of identity verification using the LDV signal. Identity verification is an important problem in which the claimed identity is either accepted or rejected by an automated system. The system design that is used is based on a loglikelihood ratio test using models that are trained during an enrollment phase. A score is computed and compared to a threshold. Performance is given in the form of False Nonmatch and False Match empirical error rates as a function of the threshold. Confidence intervals are computed that take into account correlations between the system decisions
Vocal fold vibratory and acoustic features in fatigued Karaoke singers
Session 3aMU - Musical Acoustics and Speech Communication: Singing Voice in Asian CulturesKaraoke is a popular singing entertainment particularly in Asia and is gaining more popularity in the rest of world. In Karaoke, an amateur singer sings with the background music and video (usually guided by the lyric captions on the video screen) played by Karaoke machine, using a microphone and an amplification system. As the Karaoke singers usually have no formal training, they may be more vulnerable to vocal fatigue as they may overuse and/or misuse their voices in the intensive and extensive singing activities. It is unclear whether vocal fatigue is accompanied by any vibration pattern or physiological changes of vocal folds. In this study, 20 participants aged from 18 to 23 years with normal voice were recruited to participate in an prolonged singing task, which induced vocal fatigue. High speed laryngscopic imaging and acoustic signals were recorded before and after the singing task. Images of /i/ phonation were quantitatively analyzed using the High Speed Video Processing (HSVP) program (Yiu, et al. 2010). It was found that the glottis became relatively narrower following fatigue, while the acoustic signals were not sensitive to measure change following fatigue. © 2012 Acoustical Society of Americapublished_or_final_versio
Biometrics & [and] Security:Combining Fingerprints, Smart Cards and Cryptography
Since the beginning of this brand new century, and especially since the 2001 Sept 11 events in the U.S, several biometric technologies are considered mature enough to be a new tool for security. Generally associated to a personal device for privacy protection, biometric references are stored in secured electronic devices such as smart cards, and systems are using cryptographic tools to communicate with the smart card and securely exchange biometric data. After a general introduction about biometrics, smart cards and cryptography, a second part will introduce our work with fake finger attacks on fingerprint sensors and tests done with different materials. The third part will present our approach for a lightweight fingerprint recognition algorithm for smart cards. The fourth part will detail security protocols used in different applications such as Personal Identity Verification cards. We will discuss our implementation such as the one we developed for the NIST to be used in PIV smart cards. Finally, a fifth part will address Cryptography-Biometrics interaction. We will highlight the antagonism between Cryptography – determinism, stable data – and Biometrics – statistical, error-prone –. Then we will present our application of challenge-response protocol to biometric data for easing the fingerprint recognition process
WOFEX 2021 : 19th annual workshop, Ostrava, 1th September 2021 : proceedings of papers
The workshop WOFEX 2021 (PhD workshop of Faculty of Electrical Engineer-ing and Computer Science) was held on September 1st September 2021 at the VSB – Technical University of Ostrava. The workshop offers an opportunity for students to meet and share their research experiences, to discover commonalities in research and studentship, and to foster a collaborative environment for joint problem solving. PhD students are encouraged to attend in order to ensure a broad, unconfined discussion. In that view, this workshop is intended for students and researchers of this faculty offering opportunities to meet new colleagues.Ostrav
Handbook of Vascular Biometrics
This open access handbook provides the first comprehensive overview of biometrics exploiting the shape of human blood vessels for biometric recognition, i.e. vascular biometrics, including finger vein recognition, hand/palm vein recognition, retina recognition, and sclera recognition. After an introductory chapter summarizing the state of the art in and availability of commercial systems and open datasets/open source software, individual chapters focus on specific aspects of one of the biometric modalities, including questions of usability, security, and privacy. The book features contributions from both academia and major industrial manufacturers
Assessment of the nanomechanical properties of healthy and atherosclerotic coronary arteries by atomic force microscopy
Coronary atherosclerosis is a major cause of mortality and morbidity worldwide. Despite its systemic nature, atherosclerotic plaques form and develop at “predilection” sites often associated with disturbed biomechanical forces. Therefore, computational approaches that analyse the biomechanics (blood flow and tissue mechanics) of atherosclerotic plaques have come to the forefront over the last 20 years. Assignment of appropriate material properties is an integral part of the simulation process. Current approaches for derivation of material properties rely on macro-mechanical testing and are agnostic to local variations of plaque stiffness to which collagen microstructure plays an important role. In this work we used Atomic Force Microscopy to measure the stiffness of healthy and atherosclerotic coronary arteries and we hypothesised that are those are contingent on the local microstructure. Given that the optimal method for studying mechanics of arterial tissue with this method has not been comprehensively established, an indentation protocol was firstly developed and optimised for frozen tissue sections as well as a co-registration framework with the local collagen microstructure utilising the same tissue section for mechanical testing and histological staining for collagen. Overall, the mechanical properties (Young’s Modulus) of the healthy vessel wall (median = 11.0 kPa, n=1379 force curves) were found to be significantly stiffer (p=1.3410-10) than plaque tissue (median=4.3 kPa, n=1898 force curves). Within plaques, lipid-rich areas (median=2.2 kPa, n=392 force curves) were found significantly softer (p=1.4710-4) than areas rich in collagen, such as the fibrous cap (median=4.9 kPa, n=1506 force curves). No statistical difference (p=0.89) was found between measurements in the middle of the fibrous cap (median=4.8 kPa, n=868 force curves) and the cap shoulder (median=5.1 kPa, n=638 force curves). Macro-mechanical testing methods dominate the entire landscape of material testing techniques. Plaques are very heterogenous in composition and macro-mechanical methods are agnostic to microscale variations in plaque stiffness. Mechanical testing by indentation may be better suited to quantify local variations in plaque stiffness, that are potent drivers of plaque rupture.Open Acces
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