Energy Analytics for Infrastructure: An Application to Institutional Buildings

abstract: Commercial buildings in the United States account for 19% of the total energy consumption annually. Commercial Building Energy Consumption Survey (CBECS), which serves as the benchmark for all the commercial buildings provides critical input for EnergyStar models. Smart energy management technologies, sensors, innovative demand response programs, and updated versions of certification programs elevate the opportunity to mitigate energy-related problems (blackouts and overproduction) and guides energy managers to optimize the consumption characteristics. With increasing advancements in technologies relying on the ‘Big Data,' codes and certification programs such as the American Society of Heating, Refrigerating and Air-Conditioning Engineers (ASHRAE), and the Leadership in Energy and Environmental Design (LEED) evaluates during the pre-construction phase. It is mostly carried out with the assumed quantitative and qualitative values calculated from energy models such as Energy Plus and E-quest. However, the energy consumption analysis through Knowledge Discovery in Databases (KDD) is not commonly used by energy managers to perform complete implementation, causing the need for better energy analytic framework. The dissertation utilizes Interval Data (ID) and establishes three different frameworks to identify electricity losses, predict electricity consumption and detect anomalies using data mining, deep learning, and mathematical models. The process of energy analytics integrates with the computational science and contributes to several objectives which are to 1. Develop a framework to identify both technical and non-technical losses using clustering and semi-supervised learning techniques. 2. Develop an integrated framework to predict electricity consumption using wavelet based data transformation model and deep learning algorithms. 3. Develop a framework to detect anomalies using ensemble empirical mode decomposition and isolation forest algorithms. With a thorough research background, the first phase details on performing data analytics on the demand-supply database to determine the potential energy loss reduction potentials. Data preprocessing and electricity prediction framework in the second phase integrates mathematical models and deep learning algorithms to accurately predict consumption. The third phase employs data decomposition model and data mining techniques to detect the anomalies of institutional buildings.Dissertation/ThesisDoctoral Dissertation Civil, Environmental and Sustainable Engineering 201

Multichannel analysis of normal and continuous adventitious respiratory sounds for the assessment of pulmonary function in respiratory diseases

Premi extraordinari doctorat UPC curs 2015-2016, àmbit d’Enginyeria IndustrialRespiratory sounds (RS) are produced by turbulent airflows through the airways and are inhomogeneously transmitted through different media to the chest surface, where they can be recorded in a non-invasive way. Due to their mechanical nature and airflow dependence, RS are affected by respiratory diseases that alter the mechanical properties of the respiratory system. Therefore, RS provide useful clinical information about the respiratory system structure and functioning. Recent advances in sensors and signal processing techniques have made RS analysis a more objective and sensitive tool for measuring pulmonary function. However, RS analysis is still rarely used in clinical practice. Lack of a standard methodology for recording and processing RS has led to several different approaches to RS analysis, with some methodological issues that could limit the potential of RS analysis in clinical practice (i.e., measurements with a low number of sensors, no controlled airflows, constant airflows, or forced expiratory manoeuvres, the lack of a co-analysis of different types of RS, or the use of inaccurate techniques for processing RS signals). In this thesis, we propose a novel integrated approach to RS analysis that includes a multichannel recording of RS using a maximum of five microphones placed over the trachea and the chest surface, which allows RS to be analysed at the most commonly reported lung regions, without requiring a large number of sensors. Our approach also includes a progressive respiratory manoeuvres with variable airflow, which allows RS to be analysed depending on airflow. Dual RS analyses of both normal RS and continuous adventitious sounds (CAS) are also proposed. Normal RS are analysed through the RS intensity–airflow curves, whereas CAS are analysed through a customised Hilbert spectrum (HS), adapted to RS signal characteristics. The proposed HS represents a step forward in the analysis of CAS. Using HS allows CAS to be fully characterised with regard to duration, mean frequency, and intensity. Further, the high temporal and frequency resolutions, and the high concentrations of energy of this improved version of HS, allow CAS to be more accurately characterised with our HS than by using spectrogram, which has been the most widely used technique for CAS analysis. Our approach to RS analysis was put into clinical practice by launching two studies in the Pulmonary Function Testing Laboratory of the Germans Trias i Pujol University Hospital for assessing pulmonary function in patients with unilateral phrenic paralysis (UPP), and bronchodilator response (BDR) in patients with asthma. RS and airflow signals were recorded in 10 patients with UPP, 50 patients with asthma, and 20 healthy participants. The analysis of RS intensity–airflow curves proved to be a successful method to detect UPP, since we found significant differences between these curves at the posterior base of the lungs in all patients whereas no differences were found in the healthy participants. To the best of our knowledge, this is the first study that uses a quantitative analysis of RS for assessing UPP. Regarding asthma, we found appreciable changes in the RS intensity–airflow curves and CAS features after bronchodilation in patients with negative BDR in spirometry. Therefore, we suggest that the combined analysis of RS intensity–airflow curves and CAS features—including number, duration, mean frequency, and intensity—seems to be a promising technique for assessing BDR and improving the stratification of BDR levels, particularly among patients with negative BDR in spirometry. The novel approach to RS analysis developed in this thesis provides a sensitive tool to obtain objective and complementary information about pulmonary function in a simple and non-invasive way. Together with spirometry, this approach to RS analysis could have a direct clinical application for improving the assessment of pulmonary function in patients with respiratory diseases.Los sonidos respiratorios (SR) se generan con el paso del flujo de aire a través de las vías respiratorias y se transmiten de forma no homogénea hasta la superficie torácica. Dada su naturaleza mecánica, los SR se ven afectados en gran medida por enfermedades que alteran las propiedades mecánicas del sistema respiratorio. Por lo tanto, los SR proporcionan información clínica relevante sobre la estructura y el funcionamiento del sistema respiratorio. La falta de una metodología estándar para el registro y procesado de los SR ha dado lugar a la aparición de diferentes estrategias de análisis de SR con ciertas limitaciones metodológicas que podrían haber restringido el potencial y el uso de esta técnica en la práctica clínica (medidas con pocos sensores, flujos no controlados o constantes y/o maniobras forzadas, análisis no combinado de distintos tipos de SR o uso de técnicas poco precisas para el procesado de los SR). En esta tesis proponemos un método innovador e integrado de análisis de SR que incluye el registro multicanal de SR mediante un máximo de cinco micrófonos colocados sobre la tráquea yla superficie torácica, los cuales permiten analizar los SR en las principales regiones pulmonares sin utilizar un número elevado de sensores . Nuestro método también incluye una maniobra respiratoria progresiva con flujo variable que permite analizar los SR en función del flujo respiratorio. También proponemos el análisis combinado de los SR normales y los sonidos adventicios continuos (SAC), mediante las curvas intensidad-flujo y un espectro de Hilbert (EH) adaptado a las características de los SR, respectivamente. El EH propuesto representa un avance importante en el análisis de los SAC, pues permite su completa caracterización en términos de duración, frecuencia media e intensidad. Además, la alta resolución temporal y frecuencial y la alta concentración de energía de esta versión mejorada del EH permiten caracterizar los SAC de forma más precisa que utilizando el espectrograma, el cual ha sido la técnica más utilizada para el análisis de SAC en estudios previos. Nuestro método de análisis de SR se trasladó a la práctica clínica a través de dos estudios que se iniciaron en el laboratorio de pruebas funcionales del hospital Germans Trias i Pujol, para la evaluación de la función pulmonar en pacientes con parálisis frénica unilateral (PFU) y la respuesta broncodilatadora (RBD) en pacientes con asma. Las señales de SR y flujo respiratorio se registraron en 10 pacientes con PFU, 50 pacientes con asma y 20 controles sanos. El análisis de las curvas intensidad-flujo resultó ser un método apropiado para detectar la PFU , pues encontramos diferencias significativas entre las curvas intensidad-flujo de las bases posteriores de los pulmones en todos los pacientes , mientras que en los controles sanos no encontramos diferencias significativas. Hasta donde sabemos, este es el primer estudio que utiliza el análisis cuantitativo de los SR para evaluar la PFU. En cuanto al asma, encontramos cambios relevantes en las curvas intensidad-flujo yen las características de los SAC tras la broncodilatación en pacientes con RBD negativa en la espirometría. Por lo tanto, sugerimos que el análisis combinado de las curvas intensidad-flujo y las características de los SAC, incluyendo número, duración, frecuencia media e intensidad, es una técnica prometedora para la evaluación de la RBD y la mejora en la estratificación de los distintos niveles de RBD, especialmente en pacientes con RBD negativa en la espirometría. El método innovador de análisis de SR que se propone en esta tesis proporciona una nueva herramienta con una alta sensibilidad para obtener información objetiva y complementaria sobre la función pulmonar de una forma sencilla y no invasiva. Junto con la espirometría, este método puede tener una aplicación clínica directa en la mejora de la evaluación de la función pulmonar en pacientes con enfermedades respiratoriasAward-winningPostprint (published version

Multimodal Signal Processing for Diagnosis of Cardiorespiratory Disorders

This thesis addresses the use of multimodal signal processing to develop algorithms for the automated processing of two cardiorespiratory disorders. The aim of the first application of this thesis was to reduce false alarm rate in an intensive care unit. The goal was to detect five critical arrhythmias using processing of multimodal signals including photoplethysmography, arterial blood pressure, Lead II and augmented right arm electrocardiogram (ECG). A hierarchical approach was used to process the signals as well as a custom signal processing technique for each arrhythmia type. Sleep disorders are a prevalent health issue, currently costly and inconvenient to diagnose, as they normally require an overnight hospital stay by the patient. In the second application of this project, we designed automated signal processing algorithms for the diagnosis of sleep apnoea with a main focus on the ECG signal processing. We estimated the ECG-derived respiratory (EDR) signal using different methods: QRS-complex area, principal component analysis (PCA) and kernel PCA. We proposed two algorithms (segmented PCA and approximated PCA) for EDR estimation to enable applying the PCA method to overnight recordings and rectify the computational issues and memory requirement. We compared the EDR information against the chest respiratory effort signals. The performance was evaluated using three automated machine learning algorithms of linear discriminant analysis (LDA), extreme learning machine (ELM) and support vector machine (SVM) on two databases: the MIT PhysioNet database and the St. Vincent’s database. The results showed that the QRS area method for EDR estimation combined with the LDA classifier was the highest performing method and the EDR signals contain respiratory information useful for discriminating sleep apnoea. As a final step, heart rate variability (HRV) and cardiopulmonary coupling (CPC) features were extracted and combined with the EDR features and temporal optimisation techniques were applied. The cross-validation results of the minute-by-minute apnoea classification achieved an accuracy of 89%, a sensitivity of 90%, a specificity of 88%, and an AUC of 0.95 which is comparable to the best results reported in the literature

Recent development of respiratory rate measurement technologies

Respiratory rate (RR) is an important physiological parameter whose abnormity has been regarded as an important indicator of serious illness. In order to make RR monitoring simple to do, reliable and accurate, many different methods have been proposed for such automatic monitoring. According to the theory of respiratory rate extraction, methods are categorized into three modalities: extracting RR from other physiological signals, RR measurement based on respiratory movements, and RR measurement based on airflow. The merits and limitations of each method are highlighted and discussed. In addition, current works are summarized to suggest key directions for the development of future RR monitoring methodologies

Contributo da monitorização do sistema nervoso autónomo para a abordagem do doente com instabilidade hemodinâmica em ambiente de cuidados intensivos

RESUMO: O Sistema Nervoso Autónomo, funcionalmente composto pelo Sistema Nervoso Autónomo Intrínseco, Sistema Nervoso Autónomo Extrínseco Simpático e Sistema Nervoso Autónomo Extrínseco Parassimpático, é um dos sistemas mais primitivos que garante a sobrevivência da espécie humana. A harmonia do funcionamento dos vários órgãos e sistemas depende em grande medida do equilíbrio entre os diversos componentes do Sistema Nervoso Autónomo, bem como da sua adequada interação com os restantes sistemas. Existem diversos métodos para testar o seu funcionamento: testes dos reflexos autonómicos cardiovasculares, análise da variabilidade da frequência cardíaca, determinação sérica de neurotransmissores, microneurografia e testes da função sudomotora. Na prática clínica é usual fazer-se uso dos reflexos autonómicos cardiovasculares, da análise da variabilidade cardíaca e dos testes da função sudomotora; todavia, a sua aplicabilidade nos doentes internados em ambiente de Cuidados Intensivos tem-se restringido, quase em exclusivo, à análise da variabilidade da frequência cardíaca; e, dentro da comunidade científica da Medicina Intensiva, especialidade médica com alicerces sólidos na fisiopatologia, o Sistema Nervoso Autónomo tem-se mantido à margem do interesse científico dos seus profissionais. A dúvida é legítima: não é um tema intelectualmente estimulante ou, não terá aplicabilidade na atividade clínica? No capítulo “Estudo do Sistema Nervoso Autónomo em ambiente de cuidados intensivos – estado da arte” faz-se uma revisão da literatura sobre a aplicabilidade da sua monitorização nos doentes críticos. Dessa revisão conclui-se que o estudo da correlação da variabilidade da frequência cardíaca com o prognóstico é o tema de excelência, sendo unânimes que a variabilidade da frequência cardíaca varia de forma inversa com o prognóstico. Existem igualmente alguns trabalhos que estudam a variabilidade da pressão arterial, nomeadamente o estudo do barorreflexo, uma vez mais o foco incide no prognóstico, apresentando pior prognóstico os doentes com baixa sensibilidade do barorreflexo. A pupilometria e a resposta pupilar à luz, apresentam-se como exceções ao cenário anterior, já que são utilizadas como ferramenta para titular a analgesia nos doentes críticos e para inferir as alterações da pressão intracraniana; são igualmente utilizadas para inferir o prognóstico nos doentes vítimas de anoxia cerebral e no estado de mal não convulsivo. Focando-se os estudos da avaliação do Sistema Nervoso Autónomo como ferramenta de prognóstico, sem aplicabilidade clínica direta para modificar o outcome dos doentes, este poderá ser um dos fatores limitativos à sua introdução como instrumento de monitorização na prática clínica diária das Unidades de Cuidados Intensivos. O capítulo “Monitorização do Sistema Nervoso Autónomo em ambiente de Cuidados Intensivos como ferramenta de prognóstico. Revisão sistemática” surgiu como uma necessidade natural do trabalho previamente desenvolvido. Face à evidência dos múltiplos estudos, que abordavam a avaliação da variabilidade da frequência cardíaca, havia a necessidade de se proceder a uma revisão sistemática dos mesmos. Todos os estudos publicados em ambiente de cuidados intensivos são de coorte, prospetivos ou retrospetivos, focando-se no trauma, sépsis grave e choque sético, disfunção multiorgânica, na paragem cardiorrespiratória, acidente vascular cerebral e doentes neurocirúrgicos; independentemente das variáveis estudadas, foi unânime que a variabilidade da frequência cardíaca varia de forma inversa com a gravidade clínica e com o prognóstico. Após terminar o capítulo anterior surgiram algumas dúvidas metódicas resultantes da constatação de que: não existe padronização das variáveis estudadas, nem dos métodos estudados e, é quase inexistente a aplicação dos métodos no domínio tempo-frequência nos doentes internados em ambiente de cuidados intensivos. O capítulo “Avaliação do Sistema Nervoso Autónomo pela monitorização da frequência cardíaca em ambiente de Cuidados Intensivos. Comparação de métodos” tem como objetivo fornecer um contributo para minorar estas dúvidas. Estudou-se a variabilidade da frequência cardíaca no domínio do tempo, no domínio da frequência (pelo método de Welch, pelo modelo autorregressivo e pelo método de Lomd-Scargle) e no domínio tempo-frequência (pelo método de Burg, pelo método de Lomb-Scargle, pela transformada de Wavelet e pela transformada de Hilbert-Huang) em 324 blocos de sinal eletrocardiográfico estável, obtidos em 82 doentes. Foram identificadas correlações fortes, e muito fortes, entre variáveis no domínio do tempo e variáveis no domínio da frequência, essas mesmas correlações foram replicadas com as variáveis no domínio tempo-frequência. Apesar da correlação positiva muito forte, entre os vários métodos e modelos disponíveis para estudar o balanço do Sistema Nervoso Autónomo, não existe entre eles concordância, o que reforça a necessidade de ser padronizada a metodologia do seu estudo. Durante a colheita, e o tratamento dos dados para o capítulo anterior, constatou-se que existia, em alguns doentes, uma subestimação do poder da banda HF, pelo facto dos doentes admitidos nas Unidades de Cuidados Intensivos apresentarem valores elevados da frequência respiratória. Frequências respiratórias superiores a 24 cpm ficam fora do limite superior do espectro da banda HF, não sendo por esse motivo quantificado. Esta observação deu origem a um pequeno capítulo intitulado “Variabilidade da frequência cardíaca. O espectro das bandas de alta frequência não está adequado para todos os doentes adultos internados em Cuidados Intensivos”. O capítulo “Manobra de Valsalva. Uma nova proposta para a sua utilização em doentes submetidos a ventilação mecânica invasiva” tem o objetivo de transformar a monitorização do Sistema Nervoso Autónomo num instrumento útil de orientação terapêutica nos doentes internados em ambiente de cuidados intensivos com instabilidade hemodinâmica. Apresenta-se um pequeno estudo piloto, sobre a adaptação da manobra de Valsalva durante a manobra da pausa inspiratória nos doentes submetidos a ventilação mecânica invasiva. Apesar do reduzido número de observações apresentadas, pode-se afirmar que a manobra de Valsalva é replicável nestes doentes e, que existe uma concordância da monitorização contínua do Sistema Nervoso Autónomo com as várias fases da manobra, nomeadamente na modelação vagal, a e b-adrenérgica. Por último, e de forma a dar destaque à importância da introdução da monitorização contínua do Sistema Nervoso Autónomo nas Unidades de Cuidados Intensivos, pelos métodos de monitorização no domínio tempo-frequência, apresenta-se o capítulo “Monitorização de eventos”. Neste capítulo são apresentados fenómenos de curta duração, que ocorrem com elevada frequência nas Unidades de Cuidados Intensivos, nomeadamente a troca de seringas com aminas vasoativas, a tosse e a aspiração de secreções brônquicas, e que a observação da resposta adaptativa do Sistema Nervoso Autónomo face à provocação a que é submetido, poderá nos indicar o seu estado de equilíbrio e, eventualmente na sua ausência, quais as medidas a adotar.ABSTRACT: The Autonomic Nervous System, functionally composed by the Intrinsic Autonomic Nervous System, Sympathetic Extrinsic Autonomic Nervous System and Parasympathetic Extrinsic Autonomic Nervous System, is one of the most primitive systems that is responsible for the survival of the human species. The harmony of the various organs and systems depends in a large scale on the balance between the various components of the Autonomic Nervous System, as well as their proper interaction with the other systems. There are several methods to test its functioning: cardiovascular autonomic reflex tests, heart rate variability analysis, serum determination of neurotransmitters, microneurography and sudomotor function tests. In clinical practice, it is usual to use the autonomic cardiovascular reflexes, heart rate variability analysis and sudomotor function tests; however, its applicability in patients hospitalized in the Intensive Care setting has been restricted, almost exclusively, to the analysis of heart rate variability; and among the scientific community of Intensive Medicine, a medical specialty with solid foundations in pathophysiology, the Autonomic Nervous System has been kept out of the scientific interest of its professionals. Doubt is legitimate: is it not an intellectually stimulating subject, or is it not appropriate for clinical practice? In the chapter "Study of the Autonomic Nervous System in Intensive Care Environment - State of the art" a critical review of the literature on the applicability of its monitoring in critical patients is made. This review concludes that studying the correlation between heart rate variability and prognosis is the focus, and all studies indicate that lower the heart rate variability, worse the prognosis. There are also some studies on the blood pressure variability, namely studying the baroreflex, once again the focus is on the prognosis, presenting worse prognosis the patients with low baroreflex sensitivity. Pupillometry and pupil light response is an exception to the previous scenario, since it is used as a tool to titrate analgesia in critical patients and to infer changes in intracranial pressure; it is also used as a prognostic tool in patients suffering from cerebral anoxia and in non-convulsive status epilepticus. Focusing the studies in evaluation the Autonomic Nervous System as a prognostic tool, without direct clinical applicability to modify the outcome of the patients, may be one of the limiting factors for its introduction as a monitoring instrument in the daily clinical practice of the Intensive Care Units. The chapter "Monitoring the Autonomic Nervous System in an Intensive Care environment as a prognostic tool. Systematic review "emerged as a natural need for previously developed work. Considering the multiple studies that addressed the evaluation of heart rate variability, there was a need for a systematic review of the studies, to evaluate if the results were consistent. All studies published in intensive care settings are cohort, prospective or retrospective, focusing on trauma, severe sepsis and septic shock, multiorgan dysfunction, cardiorespiratory arrest, stroke and neurosurgical patients; regardless of the variables studied, it was unanimous that heart rate variability is inversely related with clinical severity and prognosis. After finishing the previous chapter, some methodological doubts emerged: there is no standardization of the variables studied, nor of the methods, and there is almost no application of the time-frequency methods in patients hospitalized in intensive care units. The chapter "Evaluation of the Autonomic Nervous System by monitoring the heart rate variability in Intensive Care environment. Comparison of methods" try to answer those questions. Heart rate variability was studied in time domain, in frequency domain (Welch method, autoregressive model and Lomd-Scargle method) and in timefrequency domain (Burg method, Lomb-Scargle method, Wavelet transform and Hilbert- Huang transform) in 324 blocks of electrocardiographic stable signal, obtained in 82 patients. Strong and very strong correlations were identified between variables in the time domain and variables in the frequency domain, these same correlations were replicated with the variables in the time-frequency domain. Despite the very strong positive correlation between the various methods and models available to study the Autonomic Nervous System balance, there was no concordance between them, which reinforces the need to standardize the methodology of Autonomic study. During collection and treatment of data for the previous chapter, it was found that, in some patients there was an underestimation of the power of the HF band, because patients admitted to the Intensive Care Unit had higher respiratory rate values. Respiratory frequencies above 24 cpm are outside the upper limit of the HF band spectrum and are therefore not quantified. This observation originated a short chapter entitled "Variability of heart rate. The spectrum of high frequency bands is not suitable for all adult patients admitted in Intensive Care. The chapter "Valsalva maneuver. A new proposal for its use in patients submitted to mechanical ventilation" has the objective to transform the Autonomic Nervous System monitoring into a useful instrument for therapeutic orientation in Intensive Care patients with hemodynamic instability. A small pilot study was performed, to adapt the Valsalva maneuver during the inspiratory pause maneuver in patients submitted to mechanical ventilation. Despite the small number of observations presented, it can be stated that the Valsalva maneuver is replicable in these patients and there is a concordance of the continuous Autonomic Nervous System monitoring with the various phases of the maneuver, namely in the vagal, a and b-adrenergic modulation. Lastly, and to highlight the importance of the introduction of the continuous Autonomic Nervous System monitoring in Intensive Care Units, through the methods of timefrequency domain, I present the chapter "Monitoring of events". In this chapter, observation the adaptive response of the Autonomic Nervous System when exposed to short-term phenomena, like vasoactive syringes exchange, coughing and tracheal aspiration, may indicate its balance and, if necessary, what measures to take

Multivariate assessment of linear and non-linear causal coupling pathways within the central-autonomic-network in patients suffering from schizophrenia

Im Bereich der Zeitreihenanalyse richtet sich das Interesse zunehmend darauf, wie Einblicke in die Interaktions- und Regulationsprozesse von pathophysiologischen- und physiologischen Zuständen erlangt werden können. Neuste Fortschritte in der nichtlinearen Dynamik, der Informationstheorie und der Netzwerktheorie liefern dabei fundiertes Wissen über Kopplungswege innerhalb (patho)physiologischer (Sub)Systeme. Kopplungsanalysen zielen darauf ab, ein besseres Verständnis dafür zu erlangen, wie die verschiedenen integrierten regulatorischen (Sub)Systeme mit ihren komplexen Strukturen und Regulationsmechanismen das globale Verhalten und die unterschiedlichen physiologischen Funktionen auf der Ebene des Organismus beschreiben. Insbesondere die Erfassung und Quantifizierung der Kopplungsstärke und -richtung sind wesentliche Aspekte für ein detaillierteres Verständnis physiologischer Regulationsprozesse. Ziel dieser Arbeit war die Charakterisierung kurzfristiger unmittelbarer zentral-autonomer Kopplungspfade (top-to-bottom und bottom to top) durch die Kopplungsanalysen der Herzfrequenz, des systolischen Blutdrucks, der Atmung und zentraler Aktivität (EEG) bei schizophrenen Patienten und Gesunden. Dafür wurden in dieser Arbeit neue multivariate kausale und nicht-kausale, lineare und nicht-lineare Kopplungsanalyseverfahren (HRJSD, mHRJSD, NSTPDC) entwickelt, die in der Lage sind, die Kopplungsstärke und -richtung, sowie deterministische regulatorische Kopplungsmuster innerhalb des zentralen-autonomen Netzwerks zu quantifizieren und zu klassifizieren. Diese Kopplungsanalyseverfahren haben ihre eigenen Besonderheiten, die sie einzigartig machen, auch im Vergleich zu etablierten Kopplungsverfahren. Sie erweitern das Spektrum neuartiger Kopplungsansätze für die Biosignalanalyse und tragen auf ihre Weise zur Gewinnung detaillierter Informationen und damit zu einer verbesserten Diagnostik/Therapie bei. Die Hauptergebnisse dieser Arbeit zeigen signifikant schwächere nichtlineare zentral-kardiovaskuläre und zentral-kardiorespiratorische Kopplungswege und einen signifikant stärkeren linearen zentralen Informationsfluss in Richtung des Herzkreislaufsystems auf, sowie einen signifikant stärkeren linearen respiratorischen Informationsfluss in Richtung des zentralen Nervensystems in der Schizophrenie im Vergleich zu Gesunden. Die detaillierten Erkenntnisse darüber, wie die verschiedenen zentral-autonomen Netzwerke mit paranoider Schizophrenie assoziiert sind, können zu einem besseren Verständnis darüber führen, wie zentrale Aktivierung und autonome Reaktionen und/oder Aktivierung in physiologischen Netzwerken unter pathophysiologischen Bedingungen zusammenhängen.In the field of time series analysis, increasing interest focuses on insights gained how the coupling pathways of regulatory mechanisms work in healthy and ill states. Recent advances in non-linear dynamics, information theory and network theory lead to a new sophisticated body of knowledge about coupling pathways within (patho)physiological (sub)systems. Coupling analyses aim to provide a better understanding of how the different integrated physiological (sub)systems, with their complex structures and regulatory mechanisms, describe the global behaviour and distinct physiological functions at the organism level. In particular, the detection and quantification of the coupling strength and direction are important aspects for a more detailed understanding of physiological regulatory processes. This thesis aimed to characterize short-term instantaneous central-autonomic-network coupling pathways (top-to-bottom and bottom to top) by analysing the coupling of heart rate, systolic blood pressure, respiration and central activity (EEG) in schizophrenic patients and healthy participants. Therefore, new multivariate causal and non-causal linear and non-linear coupling approaches (HRJSD, mHRJSD, NSTPDC) that are able to determine the coupling strength and direction were developed. Whereby, the HRJSD and mHRJSD approaches allow the quantification and classification of deterministic regulatory coupling patterns within and between the cardiovascular- the cardiorespiratory system and the central-autonomic-network were developed. These coupling approaches have their own unique features, even as compared to well-established coupling approaches. They expand the spectrum of novel coupling approaches for biosignal analysis and thus contribute in their own way to detailed information obtained, and thereby contribute to improved diagnostics/therapy. The main findings of this thesis revealed significantly weaker non-linear central-cardiovascular and central-cardiorespiratory coupling pathways, and significantly stronger linear central information flow in the direction of the cardiac- and vascular system, and a significantly stronger linear respiratory information transfer towards the central nervous system in schizophrenia in comparison to healthy participants. This thesis provides an enhanced understanding of the interrelationship of central and autonomic regulatory mechanisms in schizophrenia. The detailed findings on how variously-pronounced, central-autonomic-network pathways are associated with paranoid schizophrenia may enable a better understanding on how central activation and autonomic responses and/or activation are connected in physiology networks under pathophysiological conditions

Heart Rate Variability analysis in patients undergoing local anesthesia

The analysis of Heart Rate Variability (HRV), the beat to beat fluctuation in the heart rate, is a non-invasive technique with a main aim in gaining information about the autonomic neural regulation of the heart. Assessment of HRV has been shown to aid clinical diagnosis and intervention strategies. However, there are quite a few conflicting reports on HRV that perhaps impede its use as a reliable clinical tool. The complex nature of different mechanisms that affect the HRV and the large number of signal processing techniques that have been used for HRV analysis are the contributing factors of these conflicting results. The aim of this study was to investigate for the first time the effect of HRV during Brachial plexus block (local anaesthesia), applied using the axillary approach. The hypothesis was that, such investigation will enable the detection of possible changes in the dynamics of the cardiovascular system due to the intravenous introduction of anaesthetic drugs during local anaesthesia. For this purpose advanced HRV signals processing techniques were developed and evaluated on data collected before and after the application of the Brachial plexus block from fourteen patients undergoing local anaesthesia. Signal processing techniques for R-wave detection, signal representation, ectopic beat detection and detrending were first developed and validated with the help of simulated signals and physiological signals from Physionet data base. After the validation stage these methods were then used to analyse the data from the locally anaesthetised patients. The ECG R-wave peak detection was carried out using the wavelet transform with first derivative of Gaussian smoothing function as the mother wavelet. The algorithm achieved accuracy and sensitivity of over 90%. The heart timing signal was used for the HRV signal representation and also for the correction of missing and/or ectopic beats. The results obtained from the ectopic beat correction algorithm showed that the algorithm managed to significantly reduce the error caused by missing and/or ectopic beats. Detrending of the HRV signal was carried out using the wavelet packet analysis algorithm which was specifically developed for this study. The respiration signal was also estimaited from the ECG signal using the ECG Derived Respiration (EDR) technique. In order to take better account of slow respiration rates and/or irregular respiratory patterns in the HRV analysis, a new method for the estimation of the variable boundaries associated with the LF and the HF band of the HRV signal was implemented. This method relies on the frequency contents of both the HRV signal and the respiration signal and uses the cross-spectrum between these two signals to obtain the boundaries related to the HF band of the signal. The boundaries related to the LF band were defined using the HRV signal spectrum alone. The boundary estimation technique was applicable in all the spectral analysis methods that were used in this study. After the pre-processing steps the clinical data was analysed using frequency and timefrequency analysis methods to obtain the parameters related to the HRV signals. Initially spectral analysis was carried out using the traditional non-parametric (Welch’s periodogram) and parametric (Autoregressive modelling) methods. Statistical analysis of the parameters obtained from both the non-parametric and the parametric methods showed significant decrease in the LF/HF ratio values within an hour of application of the block in nine out of fourteen patients. In order to overcome the inability of these methods to deal with non-stationary, time-frequency analysis techniques were used to further analyse the HRV signals. The three time-frequency analysis methods used were the ContinuousWavelet Transform (CWT), theWigner-Ville Distribution (SPWVD) and the Empirical Mode Decomposition (EMD). The analysis of the parameters estimated from these three techniques on the clinical data showed that the CWT and the EMD techniques have performed equivalently, meaning that both these methods have detected significant decrease in thirteen out of fourteen patients for the ratio values after the application of the,anaesthetic block. The presence of interference terms has caused the degradation in the performance of the SPWVD method and due to this reason it was only able to detect significant changes in the LF/HF ratio values in ten of the fourteen patients. The results suggest that due to anxiety and/or adrenaline present in the local anaesthetic mixture, the LF/HF ratio values showed a transient increase shortly after the application of the block. After this transient increase the ratio values decreased considerably and remained low as compared to the values before the application of the block. This decrease could represent the shift of the sympathovagal balance towards parasympathetic predominance and/or inhabitation of sympathetic activity due to local anaesthesia. The use of timefrequency analysis such as EMD and CWT could provide useful information about the changes caused in the dynamics of the cardiovascular system when a local anaesthetic drug is administered in a patient

Signal Processing Approaches for Cardio-Respiratory Biosignals with an Emphasis on Mobile Health Applications

We humans are constantly preoccupied with our health and physiological status. From precise measurements such as the 12-lead electrocardiograms recorded in hospitals, we have moved on to mobile acquisition devices, now as versatile as smart-watches and smart-phones. Established signal processing techniques do not cater to the particularities of mobile biomedical health monitoring applications. Moreover, although our capabilities to acquire data are growing, many underlying physiological phenomena remain poorly understood. This thesis focuses on two aspects of biomedical signal processing. First, we investigate the physiological basis of the relationship between cardiac and breathing biosignals. Second, we propose a methodology to understand and use this relationship in health monitoring applications. Part I of this dissertation examines the physiological background of the cardio-respiratory relationship and indexes based on this relationship. We propose a methodology to extract the respiratory sinus arrhythmia (RSA), which is an important aspect of this relationship. Furthermore, we propose novel indexes incorporating dynamics of the cardio-respiratory relationship, using the RSA and the phase lag between RSA and breathing. We then evaluate, systematically, existing and novel indexes under known autonomic stimuli. We demonstrate our indexes to be viable additions to the existing ones, thanks to their performance and physiological merits. Part II focuses on real-time and instantaneous methods for the estimation of the breathing parameters from cardiac activity, which is an important application of the cardio-respiratory relationship. The breathing rate is estimated from electrocardiogram and imaging photoplethysmogram recordings, using two dedicated filtering schemes, one of which is novel. Our algorithm measures this important vital rhythm in a truly real-time manner, with significantly shorter delays than existing methods. Furthermore, we identify situations, in which an important assumption regarding the estimation of breathing parameters from cardiac activity does not hold, and draw a road-map to overcome this problem. In Part III, we use indexes and methodology developed in Parts I and II in two applications for mobile health monitoring, namely, emotion recognition and sleep apnea detection from cardiac and breathing biosignals. Results on challenging datasets show that the cardio-respiratory indexes introduced in the present thesis, especially those related to the phase lag between RSA and breathing, are successful for emotion recognition and sleep apnea detection. The novel indexes reveal to be complementary to previous ones, and bring additional insight into the physiological basis of emotions and apnea episodes. To summarize, the techniques proposed in this thesis help to bypass shortcomings of previous approaches in the understanding and the estimation of cardio-respiratory coupling in real-life mobile health monitoring

Review on biomedical sensors, technologies, and algorithms for diagnosis of sleep-disordered breathing: Comprehensive survey

This paper provides a comprehensive review of available technologies for measurements of vital physiology related parameters that cause sleep disordered breathing (SDB). SDB is a chronic disease that may lead to several health problems and increase the risk of high blood pressure and even heart attack. Therefore, the diagnosis of SDB at an early stage is very important. The essential primary step before diagnosis is measurement. Vital health parameters related to SBD might be measured through invasive or non-invasive methods. Nowadays, with respect to increase in aging population, improvement in home health management systems is needed more than even a decade ago. Moreover, traditional health parameter measurement techniques such as polysomnography are not comfortable and introduce additional costs to the consumers. Therefore, in modern advanced self-health management devices, electronics and communication science are combined to provide appliances that can be used for SDB diagnosis, by monitoring a patient's physiological parameters with more comfort and accuracy. Additionally, development in machine learning algorithms provides accurate methods of analysing measured signals. This paper provides a comprehensive review of measurement approaches, data transmission, and communication networks, alongside machine learning algorithms for sleep stage classification, to diagnose SDB

Models and Analysis of Vocal Emissions for Biomedical Applications

The International Workshop on Models and Analysis of Vocal Emissions for Biomedical Applications (MAVEBA) came into being in 1999 from the particularly felt need of sharing know-how, objectives and results between areas that until then seemed quite distinct such as bioengineering, medicine and singing. MAVEBA deals with all aspects concerning the study of the human voice with applications ranging from the neonate to the adult and elderly. Over the years the initial issues have grown and spread also in other aspects of research such as occupational voice disorders, neurology, rehabilitation, image and video analysis. MAVEBA takes place every two years always in Firenze, Italy. This edition celebrates twenty years of uninterrupted and succesfully research in the field of voice analysis