Ο Έλεγχος Δομικής Ακεραιότητας (ΕΔΤ) μέσω Ακουστικής Εκπομπής, αποτελεί ένα σημαντικό εργαλείο της μηχανικής στην έγκαιρη διάγνωση δομικών σφαλμάτων και στην αύξηση της διάρκειας ζωής κτηρίων. Οι σύγχρονες εφαρμογές συστημάτων ΕΔΤ χαρακτηρίζονται από μεγάλο κόστος εφαρμογής και συντήρησης. Χρησιμοποιώντας νέες τεχνολογίες ολοκληρωμένων συστημάτων χαμηλής κατανάλωσης ισχύος, ασύρματης επικοινωνίας, καθώς επίσης και τεχνικών ψηφιακής επεξεργασίας σημάτων και αναγνώρισης προτύπων, μπορεί να δημιουργηθεί ένα σύστημα ΕΔΤ φθηνό και αποδοτικό. Στόχος μας σε αυτή την διπλωματική είναι η υλοποίηση ενός συστήματος ασύρματων αισθητήρων, ικανών να επιτελέσουν έλεγχο δομικής ακεραιότητας μέσω ακουστικής εκπομπής, χρησιμοποιώντας μικροελεγκτές LPC2148 και πομποδέκτες nRF24L01. / Structural health monitoring with acoustic emission techniques is an important engineering tool in the diagnosis of structural faults. Modern applications of SHM systems are difficult to implement and cost inefficient. By using new integrated systems technologies, wireless communications, coupled with better techniques in signal processing and pattern recognition, a much more cheap and efficient SHM system may be build. Our target in this thesis, is to implement a wireless sensor system, capable of SHM with acoustic emission, by using LPC2148 microcontrollers and nRF24L01 transceivers.

This thesis deals with detection of the natural frequencies in the material structures using algorithms working in real-time. It is used for detection of material damage. Is described physic of material, issue of discrete signals and their spectrums and methods for the calculation of the spectral components of the signal. These metods are implemented to Matlab programming environment. Methods are tested with simulated data and real signal.

De nombreuses recherches tentent d'améliorer les convertisseurs actuels en proposant de nouvelles architectures et de nouveaux procédés de fabrication. Cette évolution est longue et doit s'exécuter étape par étape. Cependant, il est possible d'utiliser des méthodes permettant de compenser les lacunes d'un composant donné avant de franchir l'étape suivante. Ces méthodes de compensation permettent de repousser les limites du composant en attendant la maturité de la génération suivante. Elles permettent également<br />de mieux comprendre les défauts actuels et d'orienter les concepteurs vers des pistes prometteuses pour leurs recherches.<br />C'est dans ce contexte que nous proposons d'étudier l'effet d'une compensation par table de correspondance uni-dimensionnelle (LUT 1D) sur un convertisseur de type à repliement et à interpolation.<br />Afin de remplir cette table de correction, nous proposons d'utiliser et d'optimiser un algorithme d'extraction des non-linéarités du composant, basé sur une analyse fréquentielle du signal converti.<br />Les paramètres sensibles de la méthode de compensation sont ensuite étudiées au travers d'expérimentations menées sur un convertisseur spécialement conçut pour cet objectif. Nous établissons qu'il est possible de calculer une table de correspondance suffisamment robuste indépendamment des variations de fréquences et de température.<br />Finalement, nous proposons une nouvelle méthode d'extraction des paramètres spectraux d'un signal à partir de ressources de calculs très faibles. Cette étude permet d'entamer le processus d'embarquement de la compensation au sein du convertisseur. Cette finalité fait partie des perspectives liées à cette thèse.

Στα πλαίσια αυτής της εργασίας παρουσιάζεται ένα ενσωματωμένο σύστημα χαμηλού κόστους το οποίο καταγράφει, αποθηκεύει και επεξεργάζεται αναπνευστικό σήμα που έχει ληφθεί κατά τη διάρκεια ανθρώπινου ύπνου. Στα κεφάλαια που ακολουθούν αναλύεται η δομή ,οι επιμέρους συνιστώσες του συστήματος καθώς και μέθοδοι επεξεργασίας του σήματος. Αρχικά λοιπόν ορίζεται το ιατρικό και θεωρητικό υπόβαθρο πάνω στο οποίο στηρίζονται οι ισχυρισμοί και μέθοδοι που ακολουθούνται. Εν συνεχεία, γίνεται εισαγωγή στους στοιχειώδεις ορισμούς όπως αυτοί του μικροελεγκτή και ενσωματωμένου συστήματος και γίνεται μια πρώτη αναφορά στο μικροελεγκτή ADuC 7026 της Analog Devices που χρησιμοποιήσαμε και στα περιφερειακά αυτού. Επίσης γίνεται και ανάλυση των στοιχειωδών χαρακτηριστικών του περιβάλλοντος μVision της Keil που μας επιτρέπουν να κάνουμε προσομοιώσεις με μηδενικό υλικό στη διάθεσή μας. Στο επόμενο κεφάλαιο γίνεται αναλυτική επεξήγηση του μικροελεγκτή μας και δίνονται επιπλέον ενδεικτικά παραδείγματα με τα οποία γίνεται κατανοητές βασικές δυνατότητες που προσφέρει αυτός και στις οποίες θα στηριχθούμε για να δομήσουμε το δικό μας πρόγραμμα. Σημειώνουμε εδώ πως ο προγραμματισμός του μικροελεγκτή και των περιφερειακών του έγινε σε γλώσσα προγραμματισμού C. Στο τέταρτο κεφάλαιο επεξηγούμε τον αλγόριθμο που χρησιμοποιήσαμε για την επεξεργασία του σήματος και τους λόγους επιλογής του. Έπειτα παραθέτουμε αναλυτικά τον κώδικα της εφαρμογής μας και τέλος καταλήγουμε σε αποτελέσματα και συμπεράσματα. / Within this thesis, we present a low cost embedded system that records, stores and processes the respiratory signal of snores obtained during human sleep. In the following chapters we analyze the structure, each component of the system and the methods being implemented. Initially we define the medical and theoretical background on which we are based to build in our program and apply our methods. Moreover, we give the basic definitions such as the microcontroller's and the embedded system’s, and we make the first presentation of The next the microcontroller ADuC 7026 of Analog Devices and its peripherals that will be used for implementation. We also present the μVision Keil environment which enables us to emulate the microcontroller having at our disposal zero hardware. The next section gives a detailed explanation of this microcontroller and some basic examples of its programming possibilities are presented that will help us with the application. The programming of the microcontroller and its peripherals was done in C programming language. In the fourth chapter we explain the algorithm that will be used for the signal processing and the reasons for its selection. Afterwards the programming of the microcontroller is given and explained in detail and finally we conclude with the results.

Submitted by Automa??o e Estat?stica (sst@bczm.ufrn.br) on 2016-07-12T17:04:52Z No. of bitstreams: 1 AlfredoRodriguesDeLima_DISSERT.pdf: 1909195 bytes, checksum: 8680571905f085a9a3f6def1f176e2db (MD5) / Approved for entry into archive by Arlan Eloi Leite Silva (eloihistoriador@yahoo.com.br) on 2016-07-19T21:51:52Z (GMT) No. of bitstreams: 1 AlfredoRodriguesDeLima_DISSERT.pdf: 1909195 bytes, checksum: 8680571905f085a9a3f6def1f176e2db (MD5) / Made available in DSpace on 2016-07-19T21:51:52Z (GMT). No. of bitstreams: 1 AlfredoRodriguesDeLima_DISSERT.pdf: 1909195 bytes, checksum: 8680571905f085a9a3f6def1f176e2db (MD5) Previous issue date: 2016-01-28 / Com o avan?o da tecnologia de equipamentos, das formas de gera??o e utiliza??o de energia, os par?metros de qualidade de energia passam a influenciar de forma mais expressiva os diversos tipos de cargas consumidoras. Atualmente, s?o muitos os tipos de equipamentos que analisam a qualidade de energia. Entretanto, existe a necessidade de criar dispositivos que, al?m de realizar medi??es e calcular par?metros, encontrem falhas, sugiram altera??es, e possam dar suporte ao gerenciamento da instala??o. Al?m disso, ? necess?rio garantir que tais dispositivos sejam acess?veis. Para manter esse equil?brio, deve ser utilizado um m?todo de medi??o de grandezas que n?o requeira grandes recursos de processamento ou de mem?ria. O trabalho mostra que aplica??o do algoritmo de Goertzel, em compara??o com a comumente utilizada FFT, permite que as medi??es sejam feitas utilizando menos recursos de hardware, disponibilizando espa?o na mem?ria para implementa??o de fun??es de gerenciamento. O ponto inicial do trabalho consiste na pesquisa dos dist?rbios que s?o mais frequentes para consumidores de baixa tens?o. Em seguida ? proposto o diagrama funcional que indicar? o que ser? medido, calculado, quais problemas ser?o detectados e que solu??es podem ser encontradas. Simulando o algoritmo de Goertzel atrav?s do Scilab, mostra-se que ? poss?vel calcular componentes de frequ?ncia de um sinal distorcido com resultados satisfat?rios. Finalmente, ? montado o prot?tipo e s?o realizados os testes, ajustando os par?metros necess?rios para que se consiga manter o dispositivo confi?vel sem aumentar seu custo. / With the progress of devices technology, generation and use of energy ways, power quality parameters start to influence more significantly the various kinds of power consumers. Currently, there are many types of devices that analyze power quality. However, there is a need to create devices, and perform measurements and calculate parameters, find flaws, suggest changes, and to support the management of the installation. In addition, you must ensure that such devices are accessible. To maintain this balance, one magnitude measuring method should be used which does not require great resources processing or memory. The work shows that application of the Goertzel algorithm, compared with the commonly used FFT allows measurements to be made using much less hardware resources, available memory space to implement management functions. The first point of the work is the research of troubles that are more common for low voltage consumers. Then we propose the functional diagram indicate what will be measured, calculated, what problems will be detected and that solutions can be found. Through the Goertzel algorithm simulation using Scilab, is possible to calculate frequency components of a distorted signal with satisfactory results. Finally, the prototype is assembled and tests are carried out by adjusting the parameters necessary for one to maintain a reliable device without increasing its cost.

This paper proposes a method of short-range indoor localization using differential phase measurements of synchronized two-tone ultrasonic signals in an Orthogonal Frequency Multiple Access (OFDMA) scheme. This indoor positioning system (IPS) operates at an ultrasonic frequency of approximately 40kHz and synchronizes using an infrared signal. The OFDMA scheme allows for a receiver to process the signals from multiple transmitters continuously without the signals interfering with each other. The phases of the signals are measured using Goertzel Filters, allowing for low-complexity frequency content analysis. A MATLAB simulation using the proposed localization method is performed using four transmitter nodes in the corners of a 2.5m x 2.5m room and a receiver node within. The designs for the synchronizing transmitter node and the receiver node are then implemented in hardware and tested at 22cm and 28cm. The work described in this paper found that the proposed IPS functions correctly in simulation, and the hardware implementation of the receiver and transmitter provides accurate distance measurements with variance as low as 0.05cm. This variance is on the same order of magnitude as the wavelength of the ultrasonic signals used. The hardware used in the implementation of this design is low-power, low-cost, and easy to implement, but it carries with it design tradeoffs. The main difficulty introduced by the hardware is the generation of imperfectly orthogonal signals due to a time-discretization error imposed by the clock of the transmitter's general purpose microcontroller. This error is theoretically and experimentally analyzed yielding closely matching values.

Les Éoliennes à Entraînement Direct (ÉED) sont équipées de Générateurs Syn- chrones à Aimants Permanents (GSAP). Leurs trois plus courantes défaillances sont la dé- magnétisation, l’excentricité (statique, dynamique et mixte) et le court-circuit inter-tour. L’analyse de la signature du courant de la machine est souvent utilisée pour rechercher des problèmes du générateur, car ces altérations introduisent des harmoniques supplémen- taires dans les courants générés. La Transformée de Fourier Rapide (TFR) est utilisée pour calculer le spectre des courants. Cependant, la TFR permet de calculer l’ensemble du spec- tre, tandis que le nombre de défauts possible et le nombre d’harmoniques introduites sont faibles. L’algorithme de Goertzel, mis en oeuvre sous forme de filtre (le filtre de Goertzel), est présenté comme une alternative plus efficace au TFR. Le spectre des courants change avec la vitesse du vent, ce qui rend la détection plus difficile. Le Filtre de Kalman Étendu (FKÉ) est proposé comme solution. Le spectre de résidus, calcule entre les courants estimés et les courants générés, est constant, quelle que soit la vitesse du vent. Cependant, l’effet des défauts est visible dans leur spectre. Lors de l’utilisation de l’FKÉ, un défi consiste à estime la matrice de covariance pour le bruit du processus. Une nouvelle méthode était développée pour ça, qui n’utilise aucune de maîtrise du filtre. Les ÉED sont placés soit dans des zones éloignées, soit dans des villes. Pour la surveillance des ÉED, des dizaines ou des centaines de kilomètres de câbles sont nécessaires. Les Réseaux de Capteurs sans Fil (RCF) sont bien adaptés pour être utilisés dans l’infrastructure de communication des ÉED. RCF ont des coûts initiaux et d’entretien plus faibles et leurs installations sont rapides. De plus, ils peuvent compléter les réseaux câblés. Différentes technologies sans fil sont comparées : les technologies à grande surface, ainsi que les technologies à courte portée qui supportent des débits de données élevés. / Direct Drive Wind Turbines (DDWTs) are equipped with Permanent Magnet Syn- chronous Generators (PMSGs). Their three most common failures are demagnetization, ec- centricity (static, dynamic and mixed) and inter-turn short circuit. Machine Current Signa- ture Analysis is often used to look for generator problems, as these impairments introduce additional harmonics into the generated currents. The Fast Fourier Transform (FFT) is utilized to compute the spectrum of the currents. However, the FFT calculates the whole spectrum, while the number of possible faults and the number of introduced harmonics is low. The Goertzel algorithm, implemented as a filter (the Goertzel filter), is presented as a more efficient alternative to the FFT. The spectrum of the currents changes with the wind speed, and thus the detection is made more difficult. The Extended Kalman Filter (EKF) is proposed as a solution. The spectrum of the residuals, computed between the estimated and the generated current, is constant, regardless of the wind speed. However, the effect of the faults is visible in the spectrum. When using the EKF, one challenge is to find out the covariance matrix of the process noise. A new method was developed in this regard, which does not use any of the matrices of the filter. DDWTs are either placed in remote areas or in cities. For the monitoring of a DDWT, tens or hundreds of kilometers of cables are necessary. Wireless Sensor Networks (WSNs) are suited to be used in the communication infrastructure of DDWTs. WSNs have lower initial and maintenance costs, and they are quickly installed. Moreover, they can complement wired networks. Different wireless technologies are com- pared - both wide area ones, as well as short range technologies which support high data rates.

The organic materials used for stator winding insulation are subject to deterioration from thermal, electrical, and mechanical stresses. Stator winding insulation breakdown due to excessive thermal stress is one of the major causes of electric machine failures; therefore, prevention of such a failure is crucial for increasing machine reliability and minimizing financial loss due to motor failure. This work focuses on the development of an efficient and reliable stator winding temperature estimation scheme for small to medium size mains-fed induction machines. The motivation for the stator winding temperature estimation is to develop a sensorless temperature monitoring scheme and provide an accurate temperature estimate that is capable of responding to the changes in the motors cooling capability. A discussion on the two major types of temperature estimation techniques, thermal model-based and parameter-based temperature techniques, reveals that neither method can protect motors without sacrificing the estimation accuracy or motor performance. Based on the evaluation of the advantages and disadvantages of these two types of temperature estimation techniques, a new online stator winding temperature estimation scheme for small to medium size mains-fed induction machines is proposed in this work. The new stator winding temperature estimation scheme is based on a hybrid thermal model. By correlating the rotor temperature with the stator temperature, the hybrid thermal model unifies the thermal model-based and the parameter-based temperature estimation techniques. Experimental results validate the proposed scheme for stator winding temperature monitoring. The entire algorithm is fast, efficient and reliable, making it suitable for implementation in real time stator winding temperature monitoring.

Dizertační práce je zaměřena na softwarově definované přijímače určené k úzkopásmové družicové komunikaci. Komunikační kanály družicových spojů zahrnujících komunikaci s hlubokým vesmírem jsou zatíženy vysokými úrovněmi šumu, typicky modelovaného AWGN, a silným Dopplerovým posuvem signálu způsobeným mimořádnou rychlostí pohybu objektu. Dizertační práce představuje možné postupy řešení výpočetně efektivní digitální downkonverze úzkopásmových signálů a systému odhadu kmitočtu nosné úzkopásmových signálů zatížených Dopplerovým posuvem v řádu násobků šířky pásma signálu. Popis navrhovaných algoritmů zahrnuje analytický postup jejich vývoje a tam, kde je to možné, i analytické hodnocení jejich chování. Algoritmy jsou modelovány v prostředí MATLAB Simulink a tyto modely jsou využity pro ověření vlastností simulacemi. Modely byly také využity k experimentálním testům na reálném signálu přijatém z družice PSAT v laboratoři experimentálních družic na ústavu radioelektroniky.

This diploma thesis deals with the design and implementation of an electronic module for acoustic detection. The module has the task of detecting a predetermined acoustic signals through them learned classification model. The module is used mainly for security purposes. To identify and classify the proposed model using machine learning techniques. Given the possibility of retraining for a different set of sounds, the module becomes a universal sound detector. With acoustic sound using the digital MEMS microphone, for which it is designed and implemented conversion filter. The resulting system is implemented into firmware microcontroller with real time operating system. The various functions of the system are realized with regard to the possible optimization (less powerful MCU or battery power). The module transmits the detection results of the master station via Ethernet network. In the case of multiple modules connected to the network to create a distributed system, which is designed for precise time synchronization using PTP protocol defined by the IEEE-1588 standard.