Signal Processing Methods for the Analysis of the Electrocardiogram

Das Elektrokardiogramm (EKG) zeichnet die elektrische Aktivität des Herzens auf der Brust- oberfläche auf. Dieses Signal kann einfach und kostengünstig aufgenommen werden und wird daher in einer Vielzahl von mobilen und stationären Anwendungen genutzt. Es ist über die letzten 100 Jahre zum Goldstandard bei der Diagnose vieler kardiologischer Krankheiten geworden. Herzerkrankungen bleiben ein relevantes Thema in unserer Gesellschaft, da sie zu 30 % aller Todesfälle weltweit führen. Allein die koronare Herzkrankheit ist die häufigste Todesursache überhaupt. Weiterhin sind 2 bis 3 % der Europäer von Herzrhythmusstörungen wie Vorhofflimmern und Vorhofflattern betroffen. Die damit verbundenen geschätzten Kosten in der Europäischen Union belaufen sich auf 26 Milliarden Euro pro Jahr. In allen diesen Fällen ist die Aufzeichnung des EKGs der erste unumgängliche Schritt für eine verlässliche Diagnose und erfolgreiche Therapie. Im Rahmen dieser Dissertation wurden eine Reihe von Algorithmen zur Signalver- arbeitung des EKG entwickelt, die automatisch die rhythmischen und morphologischen Eigenschaften aus dem EKG extrahieren und dadurch den diagnostischen Prozess und die Entscheidungsfindung des Arztes unterstützen. In einem ersten Projekt wurde das Phänomen der postextrasystolischen T-Wellen-Änderung (PEST) untersucht. Die aus der PEST ex- trahierten Biomarker haben wir als Prädiktoren für Herzversagen postuliert. Ein zweites Projekt handelte vom Entwurf eines akkuraten Algorithmus zur Detektion und Annotation der P-Welle im EKG. Als Referenz während der Entwicklung wurden intrakardial gemessene Signale verwendet. Eine dritte Untersuchg hatte das Ziel, das physiologische Phänomen der respiratorischen Sinusarrhythmie (RSA) besser zu verstehen. In diesem Projekt wurde ein Algorithmus zur Trennung der Herzratenvariabilität (HRV) in ihre atmungsabhängige und ihre atmungsunabhn ̈gige Komponente untersucht. Letzterer Anteil der HRV könnte neue Erkenntnisse über die Regulationsmechanismen des kardiovaskulären Systems liefern. In der vierten und letzten Studie wurde der Einfluss mentaler Belastung auf das EKG während der Autofahrt untersucht. Eine Vielzahl von Deskriptoren wurden gefunden, die eine gefährliche mentale Beanspruchung detektieren und somit den Fahrer vor einem möglichen Unfall schützen können. Wir schließen aus diesen Untersuchungen, dass gut entwickelte Methoden der Signalver- arbeitung des EKG das Potential haben, die Belastung der Patienten, die an Herzerkrankungen leiden, und die Anzahl der Verkehrsunfälle zu reduzieren

Matlab

This book is a collection of 19 excellent works presenting different applications of several MATLAB tools that can be used for educational, scientific and engineering purposes. Chapters include tips and tricks for programming and developing Graphical User Interfaces (GUIs), power system analysis, control systems design, system modelling and simulations, parallel processing, optimization, signal and image processing, finite different solutions, geosciences and portfolio insurance. Thus, readers from a range of professional fields will benefit from its content

A systems approach to analyze the robustness of infrastructure networks to complex spatial hazards

Ph. D. ThesisInfrastructure networks such as water supply systems, power networks, railway networks, and road networks provide essential services that underpin modern society’s health, wealth, security, and wellbeing. However, infrastructures are susceptible to damage and disruption caused by extreme weather events such as floods and windstorms. For instance, in 2007, extensive disruption was caused by floods affecting a number of electricity substations in the United Kingdom, resulting in an estimated damage of GBP£3.18bn (US$4bn). In 2017, Hurricane Harvey hit the Southern United States, causing an approximated US$125bn (GBP£99.35bn) in damage due to the resulting floods and high winds. The magnitude of these impacts is at risk of being compounded by the effects of Climate Change, which is projected to increase the frequency of extreme weather events. As a result, it is anticipated that an estimated US$3.7tn (GBP£2.9tn) in investment will be required, per year, to meet the expected need between 2019 and 2035. A key reason for the susceptibility of infrastructure networks to extreme weather events is the wide area that needs to be covered to provide essential services. For example, in the United Kingdom alone there are over 800,000 km of overhead electricity cables, suggesting that the footprint of infrastructure networks can be as extended as that of an entire Country. These networks possess different spatial structures and attributes, as a result of their evolution over long timeframes, and respond to damage and disruption in different and complex ways. Existing approaches to understanding the impact of hazards on infrastructure networks typically either (i) use computationally expensive models, which are unable to support the investigation of enough events and scenarios to draw general insights, or (ii) use low complexity representations of hazards, with little or no consideration of their spatial properties. Consequently, this has limited the understanding of the relationship between spatial hazards, the spatial form and connectivity of infrastructure networks, and infrastructure reliability. This thesis investigates these aspects through a systemic modelling approach, applied to a synthetic and a real case study, to evaluate the response of infrastructure networks to spatially complex hazards against a series of robustness metrics. In the first case study, non-deterministic spatial hazards are generated by a fractal method which allows to control their spatial variability, resulting in spatial configurations that very closely resemble natural phenomena such as floods or windstorms. These hazards are then superimposed on a range of synthetic network layouts, which have spatial structures consistent with real infrastructure networks reported in the literature. Failure of network components is initially determined as a function of hazard intensity, and cascading failure of further components is also investigated. The performance of different infrastructure configurations is captured by an array of metrics which cover different aspects of robustness, ranging from the proneness to partitioning to the ability to process flows in the face of disruptions. Whereas analyses to date have largely adopted low complexity representations of hazards, this thesis shows that consideration of a high complexity representation which includes hazard spatial variability can reduce the robustness of the infrastructure network by nearly 40%. A “small-world” network, in which each node is within a limited number of steps from any other node, is shown to be the most robust of all the modelled networks to the different structures of spatial hazard. The second case study uses real data to assess the robustness of a power supply network operating in the Hull region in the United Kingdom, which is split in high and low voltage lines. The spatial hazard is represented by a high-resolution wind gust model and tested under current and future climate scenarios. The analysis reveals how the high and low voltage lines interact with each other in the event of faults, which lines would benefit the most from increased robustness, and which are most exposed to cascading failures. The second case study also reveals the importance of the spatial footprint of the hazard relative to the location of the infrastructure, and how particular hazard patterns can affect low voltage lines that are more often located in exposed areas at the edge of the network. The impact of Climate Change on windstorms is highly uncertain, although it could further reduce network robustness due to more severe events. Overall the two case studies provide important insights for infrastructure designers, asset managers, the academic sector, and practitioners in general. In fact, in the first case study, this thesis defines important design principles, such as the adoption of a small-world network layout, that can integrate the traditional design drivers of demand, efficiency, and cost. In the second case study, this thesis lays out a methodology that can help identify assets requiring increased robustness and protection against cascading failures, resulting in more effective prioritized infrastructure investments and adaptation plans

Housing quality and lost (public) space in Croatia

IN ENGLISH: In the post-socialist period and within the current social transition context, urban and rural Croatia has, just like other transition countries, experienced many changes in the social structure and space. One example is the housing quality which is a replica of the situation in the Croatian society and has also undergone some major changes. Socially oriented housing construction co-financed by the state and the cities is in an unfavourable position compared to private housing construction. In the last twenty years the amount of the social housing construction has been only a minor part of the total contruction work in the country. For instance, out of nine newly planned residential housing developments in Zagreb, the capital city, only three have been completed and the work on the rest of them has stopped and is unlikely to continue. Private construction work prevails especially on the edge of the city and is characterised by high density housing. This type of housing construction doesn't benefit the majority of citizens in search of accommodation (price per square meter is too high, low-quality building). There is also a big problem of the community facilities (primary and secondary infrastructure, schools, kindergartens, playgrounds, green areas, sidewalks, public transport etc.). The existing globalisation-transition circumstances of the Croatian society corroborate the fact which experts of various profiles often point out: ignoring the process of (urban) planning will irreparably damage the space. The city transformation shows the absence of comprehensive urban planning which results in an ever increasing number of random buildings which do not fit in the surroundings. This leads up to yet another important issue – the shrinking and, in some cases, disappearance of public space which becomes the “lost space“. In recent years there has been a lot of building in the city core and on the edge which does not quite fit in the existing urban structure, image or the skyline of the city. The current situation in the process of planning can be characterized as a conflict and imbalance between the powerful actors (mostly political and economic) and less powerful actors (mostly professional and civil). The actors who have the political power and influence and the ones who possess the capital are forming an “alliance” between two important layers of the social structure. The lack of civil and professional actors, “lost spatial actors”, and therefore of civic aggregation is also present and that is also the cause of public space “disappearance” and undermined process of public participation. --------------- IN CROATIAN: U postsocijalističkom razdoblju i trenutnom tranzicijskom kontekstu urbana i ruralna Hrvatska su, kao i ostale tranzicijske zemlje, doživjele mnoge promjene u društvenoj strukturi i samom prostoru. Na primjeru kvalitete stanovanja kao replike stanja u hrvatskom društvu mogu se vidjeti značajne promjene. Društveno usmjerena stambena izgradnja sufinancirana od strane države i gradova je stoga rjeđa i u nepovoljnijoj je situaciji prema privatnoj stanogradnji. Zadnjih dvadeset godina udjel socijalne stambene gradnje je zanemariv u ukupnoj izgradnji na razini zemlje. Primjerice, od devet planiranih stambenih naselja izgrađenih po modelu POS-a u Zagrebu samo su tri i završena. Na ostalima je proces gradnje zastao i ne čini se da će se privesti kraju. Privatna je gradnje prisutnija, posebno na rubovima grada, a obilježava je visoka gustoća gradnje. Ovakav tip gradnje ne odgovara većini stanovnika koji su u procesu potražnje stambene nekretnine (visoka cijena kvadratnog metra, a slaba kvaliteta gradnje). Postoji također i problem nedostatne opremljenosti susjedstva (primarna i sekundarna infrastruktura, škole, vrtići, igrališta, zelene površine, pješačke staze, javni transport itd.). Navedene globalizacijsko-tranzicijske okolnosti hrvatskog društva potvrđuju ono što eksperti različitih profila ističu, a to je da će ignoriranje procesa (urbanog) planiranja nepovratno uništiti prostor gradova. Ovakve transformacije pokazuju nedostatak sustavnog urbanog planiranja što rezultira sve većim brojem zgrada koje se ne uklapaju u neposrednu okolinu. To nadalje dovodi do drugog važnog aspekta – smanjivanja i u nekim slučajevima, nestanka javnog prostora koji postaje „izgubljeni prostor“. Posljednjih je godina izgrađen velik broj zgrada, i u središtu i na rubovima grada, koje se ne uklapaju u postojeću urbanu strukturu, izgled ili vizuru grada. Ovakvu situaciju obilježavaju sukob i neravnoteža između moćnijih društvenih aktera (većinom političkih i ekonomskih) i onih manje moćnih (većinom profesionalnih i civilnih). Politički i ekonomski akteri se često povezuju u „savez“ dvaju najjačih u društvenoj strukturi. S druge strane nedostatak utjecaja civilnih i profesionalnih aktera kao „izgubljenih prostornih aktera“ dovodi do „nestanka“ javnih prostora te smanjenja važnosti procesa participacije (sudjelovanja javnosti)