Les phénomènes de couplage électromagnétique entre les lignes aé- riennes de transmission d\'énergie et des structures voisines sont inévitables, surtout dans les zones densément peuplées. Les effets indésirables découlants de cette proximité sont variés, allant de l\'établissement des tensions dangereuses à l\'apparition de phénomènes de corrosion dus au courant alternatif. L\'étude de cette classe de problèmes est nécessaire pour assurer la sécurité dans les alentours de la zone d\'interaction et aussi pour préserver l\'intégrité des équipements et des dispositifs présents. Cependant, la modélisation compl ète de ce type d\'application implique la représentation tridimensionnelle de la région d\'intérêt et nécessite des méthodes numériques de calcul de champs spécifiques. Dans ces travaux, des problèmes liés à la circulation de courants électriques dans le sol (ou de couplage dit conductif) seront abordés avec la méthode des éléments finis. D\'autres problèmes résultants de la variation temporelle des champs électromagnétiques (ou de couplage dit inductif) seront aussi considérés et traités avec la méthode PEEC (Partial Element Equivalent Circuit) généralisée. Plus précisément, une condition limite particulière sur le potentiel électrique est proposée pour tronquer le domaine de calcul dans l\'analyse par éléments finis des problèmes de couplage conductif et une formulation PEEC complète pour la modélisation de problèmes de couplage inductif est présentée. Des con gurations tests de complexités croissantes sont considérées pour valider les approches précédentes. Ces travaux visent ainsi à apporter une contribution à la modélisation de cette classe de problèmes, qui tendent à devenir communs avec l\'expansion des réseaux électriques. / Electromagnetic coupling phenomena between overhead power transmission lines and other nearby structures are inevitable, especially in densely populated areas. The undesired effects resulting from this proximity are manifold and range from the establishment of hazardous potentials to the outbreak of alternate current corrosion phenomena. The study of this class of problems is necessary for ensuring security in the vicinities of the interaction zone and also to preserve the integrity of the equipment and of the devices there present. However, the complete modeling of this type of application requires the three- -dimensional representation of the region of interest and needs specific numerical methods for field computation. In this work, the modeling of problems arising from the flow of electrical currents in the ground (the so-called conductive coupling) will be addressed with the finite element method. Those resulting from the time variation of the electromagnetic fields (the so-called inductive coupling) will be considered as well, and they will be treated with the generalized PEEC (Partial Element Equivalent Circuit) method. More specifically, a special boundary condition on the electric potential is proposed for truncating the computational domain in the finite element analysis of conductive coupling problems, and a complete PEEC formulation for modeling inductive coupling problems is presented. Test configurations of increasing complexities are considered for validating the foregoing approaches. These works aim to provide a contribution to the modeling of this class of problems, which tend to become common with the expansion of power grids.

Orientador: André Christóvão Pio Martins / Coorientador: André Nunes de Souza / Banca: Oscar Armando Maldonado Astorga / Banca: Pedro da Costa Junior / Resumo: Este trabalho mostra o estudo de uma linha de transmissão onde ocorreram desligamentos causados por descargas atmosféricas. Esse estudo foi feito a partir de informações de desligamentos de linhas de transmissão da concessionária e dados extraídos de um sistema de análise e monitoramento de descargas atmosféricas. Para esse trecho da linha de transmissão foram identificadas incidências de descargas atmosféricas que causaram desligamentos, bem como descargas que não causaram desligamentos. Baseados nestas informações foram efetuadas medições em campo de resistência de aterramento dos contrapesos e da resistividade do solo, onde foi possível constatar através dos resultados que algumas torres apresentaram valores que ultrapassaram os valores normatizados. O levantamento dessas informações é o principal foco deste estudo, que visa fornecer subsídios para a identificação de torres problemáticas. Uma proposta clássica utilizada para melhorar o desempenho desta linha de transmissão frente à incidência de descargas atmosféricas foi testada mas seu resultado não foi muito satisfatário / Abstract: This paper shows the study of a transmission line where outages occurred because of lightnings. The study was made from information that came from the power utility transmission line disconnection and data obtained from lightnings analyses and monitoring system. For this part of the transmission line it was identified incidence of lightning that caused outages, as well as incidences that did not cause outages. Based on this information, it was performed field measurements of ground resistance counterpoise and resistivity where is was possible to find, trough the results that some of the towers present numbers trepassed the normal values. Coming up with this information is this information is the main goal of this study that aims to offer to identify the towers that contains problems. A classical proposal used to improve the performance of this transmission line facing the incidence of lightnings was tested but the result wasn't very satisfactory / Mestre

Negation is a part of language that humans engage in pretty much from the onset of speech. Negation appears at first glance to be harder to grasp than object or action labels, yet this thesis explores how this family of ‘concepts’ could be acquired in a meaningful way by a humanoid robot based solely on the unconstrained dialogue with a human conversation partner. The earliest forms of negation appear to be linked to the affective or motivational state of the speaker. Therefore we developed a behavioural architecture which contains a motivational system. This motivational system feeds its state simultaneously to other subsystems for the purpose of symbol-grounding but also leads to the expression of the robot’s motivational state via a facial display of emotions and motivationally congruent body behaviours. In order to achieve the grounding of negative words we will examine two different mechanisms which provide an alternative to the established grounding via ostension with or without joint attention. Two large experiments were conducted to test these two mechanisms. One of these mechanisms is so called negative intent interpretation, the other one is a combination of physical and linguistic prohibition. Both mechanisms have been described in the literature on early child language development but have never been used in human-robot-interaction for the purpose of symbol grounding. As we will show, both mechanisms may operate simultaneously and we can exclude none of them as potential ontogenetic origin of negation.

<p>In order to achieve better lightning protection and electromagnetic compatibility (EMC) requirements, the needs for a proper grounding system and the knowledge of its transient behaviour become crucial. </p><p>The present work is focused towards developing engineering models for transient analysis of grounding system with sufficient accuracy and simplicity for lightning studies. Firstly, the conventional uniform transmission line approach for a single grounding conductor is modified and extended to grounding grids. Secondly, in order to overcome the drawbacks of all the existing transmission line approaches, for the first time, a non-uniform transmission line approach is developed for modelling the transient behaviour of different types of grounding systems. The important feature of such an approach is in its capability to include the electromagnetic couplings between different parts of the grounding system using space and time dependent per-unit length parameters.</p><p>High voltages and currents induced in the grounding systems due to lightning always produce ionization in the soil. This phenomenon should be included during the transient analysis of grounding systems. In the present work, an improved soil ionization model including residual resistivity in ionization region is developed. The fact that there exists residual resistivity in ionization region (7 % of the original soil resistivity) can be proved by the experiments reported in the literature and the experiments carried out at the high voltage lab of Uppsala University. The advantage of including residual resistivity is that the beneficial influence of soil ionization in reducing the potential rise of grounding system will not be overestimated, especially in high resistivity soil.</p><p>Finally, the transmission line approaches are adopted for studying the response of grounding systems due to lightning for different applications. These are, influence of soil parameters on the transient behaviour of grounding systems, transient analysis of grounding structures in stratified soils, investigation of the validity of existing definitions for effective length/area of different grounding structures, current distribution in the shields of under ground cables associated with communication tower, and influence of insulator flashover and soil ionization around the pole footing on surge propagation in Swedish railway system.</p>

In order to achieve better lightning protection and electromagnetic compatibility (EMC) requirements, the needs for a proper grounding system and the knowledge of its transient behaviour become crucial. The present work is focused towards developing engineering models for transient analysis of grounding system with sufficient accuracy and simplicity for lightning studies. Firstly, the conventional uniform transmission line approach for a single grounding conductor is modified and extended to grounding grids. Secondly, in order to overcome the drawbacks of all the existing transmission line approaches, for the first time, a non-uniform transmission line approach is developed for modelling the transient behaviour of different types of grounding systems. The important feature of such an approach is in its capability to include the electromagnetic couplings between different parts of the grounding system using space and time dependent per-unit length parameters. High voltages and currents induced in the grounding systems due to lightning always produce ionization in the soil. This phenomenon should be included during the transient analysis of grounding systems. In the present work, an improved soil ionization model including residual resistivity in ionization region is developed. The fact that there exists residual resistivity in ionization region (7 % of the original soil resistivity) can be proved by the experiments reported in the literature and the experiments carried out at the high voltage lab of Uppsala University. The advantage of including residual resistivity is that the beneficial influence of soil ionization in reducing the potential rise of grounding system will not be overestimated, especially in high resistivity soil. Finally, the transmission line approaches are adopted for studying the response of grounding systems due to lightning for different applications. These are, influence of soil parameters on the transient behaviour of grounding systems, transient analysis of grounding structures in stratified soils, investigation of the validity of existing definitions for effective length/area of different grounding structures, current distribution in the shields of under ground cables associated with communication tower, and influence of insulator flashover and soil ionization around the pole footing on surge propagation in Swedish railway system.

La confiance de l'homme envers la machine est une caractéristique essentielle du contrôle supervisé. En effet, des contres performances du couple homme-machine provoquées par un mauvais niveau de confiance (insuffisant ou excessif) peuvent conduire à des dégâts matériels ou humains. Il est donc nécessaire d'évaluer la confiance de l'homme pour anticiper de telles situations et ainsi empêcher leur réalisation. C'est pourquoi, dans cette thèse, nous proposons un modèle d'évaluation de la confiance. Pour cela, nous avons défini deux modèles. Le premier est un modèle de dialogue basé sur la théorie du grounding et spécifique au contrôle supervisé. Le second est un modèle d'évaluation de la confiance qui décrit le lien entre la confiance de l'homme et l'observation de sa stratégie de dialogue à l'aide du premier modèle. Cet apport théorique est accompagné de deux expérimentations. Elles sont contextualisées dans le domaine du contrôle multi-drones et plus spécifiquement pour les opérations de surveillance et d'interception. La première expérience, à but exploratoire, met en évidence l'existence d'un lien entre confiance et dialogue. La seconde permet de tester la validation de notre modèle d'évaluation de la confiance. Cette thèse apporte donc les bases d'une approche objective de l'évaluation de la confiance à partir de l'observation du dialogue homme-machine.

Answer set programming (ASP) is a declarative approach to solving search problems. Logic programming constitutes the foundation of ASP. ASP is not a proof-theoretical approach where you get solutions by answer substitutions. Instead, the problem is represented by a logic program in such a way that models of the program according to the answer set semantics correspond to solutions of the problem. Answer set solvers (Smodels, Cmodels, Clasp, and Dlv) are used for finding answer sets of a given program. Although users can write programs with variables for convenience, current answer set solvers work on ground logic programs where there are no variables. The grounding step of ASP generates a propositional instance of a logic program with variables. It may generate a huge propositional instance and make the search process of answer set solvers more difficult. Model generation theorem provers (Paradox, Darwin, and FM-Darwin) have the capability of producing a model when the first-order input theory is satisfiable. This work proposes the use of model generation theorem provers as computational engines for ASP. The main motivation is to eliminate the grounding step of ASP completely or to perform it more intelligently using the model generation system. Additionally, regardless of grounding, model generation systems may display better performance than the current solvers. The proposed method can be seen as lifting SAT-based ASP, where SAT solvers are used to compute answer sets, to the first-order level for tight programs. A completion procedure which transforms a logic program to formulas of first-order logic is utilized. Besides completion, other transformations which are necessary for forming a firstorder theory suitable for model generation theorem provers are investigated. A system called Completor is implemented for handling all the necessary transformations. The empirical results demonstrate that the use of Completor and the theorem provers together can be an eective way of computing answer sets. Especially, the run time results of Paradox in the experiments has showed that using Completor and Paradox together is favorable compared to answer set solvers. This advantage has been more clearly observed for programs with large propositional instances, since grounding can be a bottleneck for such programs.

Οι πύργοι ελέγχου αεροδρομίων αποτελούν βασικό συστατικό για την ομαλή και συνεχή εξυπηρέτηση των πτήσεων πολιτικών και στρατιωτικών αεροσκαφών. Βρίσκονται εγκατεστημένοι σε κάθε αεροδρόμιο και αποτελούν το υψηλότερο κτίριο στο περιβάλλοντα χώρο, πράγμα που δικαιολογεί και τον μεγάλο αριθμό κεραυνικών πληγμάτων που μπορούν να δεχτούν. Σκοπός αυτής της διπλωματικής εργασίας είναι η μελέτη ενός συστήματος αντικεραυνικής προστασίας που βρίσκεται εγκατεστημένο σε έναν πύργο ελέγχου αεροδρομίου. Η απόδοση του συστήματος αντικεραυνικής προστασίας διαδραματίζει σημαντικό ρόλο στην αποτελεσματική λειτουργία του πύργου ελέγχου και στη γενικότερη αποτελεσματική λειτουργία του αερολιμένα. Με τη χρήση του προγράμματος εξομοίωσης αναλογικών και ψηφιακών κυκλωμάτων Orcad-Pspice, προσομοιώνεται το σύστημα αντικεραυνικής προστασίας, με βάση τον πύργο ελέγχου που του διεθνούς αερολιμένα Ελ. Βενιζέλος, μετράται το δυναμικό στη βάση του πύργου ελέγχου και τα ρεύματα στους αγωγούς καθόδου, όταν κεραυνός πλήττει το σύστημα συλλεκτήριων αγωγών. / The airport traffic control towers are a key component for the smooth and continuous service flights for both political and military aircraft. They are located at each airport and are the highest building in the surroundings, which justifies the number of lightning strikes that accepts. The purpose of this thesis is the study of a lightning protection system which is installed in an airport control tower. The efficiency of the lightning protection system constitute an important role in the effective operation of the control tower and the overall efficient operation of the airport. Using the analog and digital circuits simulation program Orcad-Pspice, the lightning protection system simulated , based on the control tower to the International airport Eleftherios Venizelos , the measured potential at the base of the control tower and the currents in the downconductors , when lightning strikes the collectors system

Γείωση είναι η αγώγιμη σύνδεση ενός σημείου κάποιου κυκλώματος ή ενός μη-ρευματοφόρου μεταλλικού αντικειμένου μιας εγκατάστασης με το έδαφος, με σκοπό να αποκτήσουν το ίδιο δυναμικό με τη γη, το οποίο θεωρείται –κατά σύμβαση- ίσο με μηδέν. Σκοπός ενός συστήματος γείωσης είναι να μεταφέρει και να διαχέει το ρεύμα σφάλματος στη γη, εμφανίζοντας τη μικρότερη δυνατή αντίσταση στη διέλευση του ρεύματος στον ελάχιστο δυνατό χρόνο. Με αυτόν τον τρόπο ελαττώνεται ο κίνδυνος ηλεκτροπληξίας και παρέχεται ασφάλεια κατά την εκδήλωση σφάλματος ή σε περίπτωση κεραυνού, τόσο για τους χρήστες όσο και για τον εξοπλισμό της ηλεκτρολογικής εγκατάστασης. Αποτελεί απαραίτητο τμήμα των ηλεκτρικών εγκαταστάσεων για να εξασφαλιστεί η σωστή λειτουργία τους αλλά και η ποιότητα της παρεχόμενης ηλεκτρικής ισχύος. Τέλος παρέχει ένα δυναμικό αναφοράς για τα ηλεκτρικά σήματα στον τομέα των τηλεπικοινωνιών. Για να επιτευχθούν οι παραπάνω στόχοι πρέπει η αντίσταση γείωσης να έχει πολύ χαμηλή τιμή. Υπάρχουν περιπτώσεις που είναι αδύνατη η τοποθέτηση περισσοτέρων του ενός ηλεκτροδίου διότι η εργασία είναι αρκετά δαπανηρή , είτε λόγω της δομής του εδάφους, είτε λόγω του ανεπαρκή χώρου. Μια εναλλακτική μέθοδος που έχει αναπτυχθεί είναι η χρήση βελτιωτικών υλικών γείωσης γύρω από τα ηλεκτρόδια. Στην παρούσα διπλωματική εργασία τοποθετήθηκαν ηλεκτρόδια γείωσης στο χώρο του Πανεπιστημίου Πατρών και έγινε μέτρηση των αντιστάσεων τους, με σκοπό τη μελέτη της συμπεριφοράς διαφόρων βελτιωτικών υλικών γείωσης σε συνάρτηση με το χρόνο και τις περιβαλλοντικές συνθήκες. Ειδικότερα η διπλωματική αυτή εργασία αποτελείται από τα εξής κεφάλαια: Στο κεφάλαιο 1 πραγματοποιείται μια αναφορά στην ορολογία και στις βασικές αρχές που διέπουν τα συστήματα γείωσης. Ακόμη γίνεται αναφορά στα είδη των ηλεκτροδίων γείωσης και στις διατάξεις που υπάρχουν. Δίνεται επίσης ο ορισμός της αντίστασης γείωσης και παρουσιάζονται οι μέθοδοι μέτρησης της τιμής της.Στο κεφάλαιο 2 περιγράφεται η έννοια και ο ορισμός της ειδικής αντίστασης εδάφους. Στην συνέχεια παρουσιάζονται οι παράγοντες που την ειδική αντίσταση επηρεάζουν και γίνεται αναφορά στους τρόπους μέτρησης της. Τέλος αναφέρονται τρόποι διόρθωσης της αντίστασης γείωσης σε περίπτωση που οι τιμές τις είναι εκτός των επιτρεπτών ορίων. Στο κεφάλαιο 3 γίνεται αναφορά στα βελτιωτικά υλικά γειώσεων και στις βασικές αρχές που τα διέπουν. Επίσης παρουσιάζεται το βελτιωτικό που χρησιμοποιήθηκε στην παρούσα διπλωματική εργασία. Στο κεφάλαιο 4 αναφερόμαστε στα όρια ασφάλειας που πρέπει να πληροί ένα σύστημα γείωσης. Περιγράφεται η αντίσταση του ανθρώπινου σώματος καθώς και οι παράγοντες που επιδρούν στην περίπτωση ηλεκτροπληξίας. Τέλος, με την βοήθεια των ισοδύναμων κυκλωμάτων κατά την διάρκεια του βραχυκυκλώματος δίνονται τα επιτρεπτά όρια τάσης επαφής και βηματικής τάσης. Στο κεφάλαιο 5 περιγράφεται η διεξαγωγή του πειράματος με αναφορά στην εγκατάσταση και στην διαδικασία μέτρησης των ηλεκτροδίων. Στην συνέχεια γίνεται επεξεργασία των μετρήσεων με χρήση διαγραμμάτων. Τελικά καταλήγουμε σε χρήσιμα συμπεράσματα και γίνονται κάποιες προτάσεις για προέκταση της συγκεκριμένης διπλωματικής εργασίας. Τέλος, η διπλωματική εργασία ολοκληρώνεται με το Παράρτημα, στο οποίο δίνονται αναλυτικά οι πίνακες με τα μετεωρολογικά δεδομένα την περίοδο που πάρθηκαν οι μετρήσεις. / Grounding is the conductive connection of a circuit’s point, or of a non-current carrying metallic object of an installation to the ground, in order to obtain the same potential as the earth, which is, by convention, equal to zero. The objective of a grounding system is to transfer and dissipate the fault current to earth, showing the least possible resistance to the passage of current to the minimum possible time. Thereby decreasing the risk of electric shock and provide security in the event of error or in case of lightning, both for users and for the installation of electrical equipment. Finally, provides a reference potential for the electrical signals in the telecommunications sector. To achieve these objectives, the grounding resistance should have very low value. There are cases where it is impossible to insert more than one electrode because the process is quite expensive, either because of the structure of the soil, either because of insufficient space. An alternative method that has been developed is the use of ground enhancing compounds around the ground electrodes. In this diploma thesis grounding electrodes placed in the university of Patras and their resistance was measured, with the aim of studding the behavior of various materials ground improvement in relation to time and environmental conditions. The earthing system is an essential part of power networks, is required for correct operation of the electricity supply network and to ensure good power quality. Specifically this thesis consists of the following chapters: Chapter 1 includes a reference to the terminology and basic principles of grounding systems. Also is referring to the existing types of grounding electrodes and their arrangements. It also gives the definition of ground resistance and presents methods of measuring its value. Chapter 2 describes the concept and definition of soil resistivity. Then follow the factors that affect resistivity and are mentioned ways of measurement. Finally it is mentioned the way of improving the ground resistance if the measured values are unacceptable. Chapter 3 refers to the ground improvement materials and their principles. Also it is presented the ground enhancing compound which was used in this diploma thesis. Chapter 4 is referring to the safety limits of a grounding system. Therefore is described the resistance of the human body and the affecting in case of electric shock. Finally, with the help of equivalent circuits during short circuit the permissible values of touch and step voltages. Chapter 5 describes to the experiment procedure referring to the installation and the process of the measurements. Then follows the processing of the measurements with diagrams. Eventually we arrive at useful conclusions and made some suggestions for extension of this thesis.Finally, in the Appendix there are the meteorological data for the months during which the experiment took place.

Current practice in U.S. underground coal mine high-voltage distribution systems is to attempt to limit ground fault current to 25 Amperes and de-energize the circuit at 10 Amperes. However, the significant amount of system capacitance due to the use of shielded cables can cause ground fault current to be two or three times the intended ground fault limit. Consequently, this practice can cause several issues such as ground fault currents significantly exceeding the neutral grounding resistor current limit, loss of relay selectivity in the distribution system, and transient overvoltages in certain ground fault situations. These issues are solved to some extent by using a resonance grounded system, currently used in some other countries. However, a shortcoming of traditional resonance grounded systems is the inability to deal with the harmonic components existing in ground fault current. With the increasing use of nonlinear sources such as variable frequency drives, the proportion of harmonic components in ground fault current can be significant. Consequently, although the fundamental component can be almost fully compensated in a traditional resonance grounded system, the harmonic components can still be large enough to maintain arcing and cause personal injury and equipment damage. In this dissertation, a novel method is developed to perform real-time prediction of the harmonics in ground fault currents. Methods for neutralizing the ground fault current harmonics and identifying ground fault location are also developed. Results indicate that the combination of traditional high-resistance grounding and active current injection to neutralize harmonics in the ground fault has the potential to significantly reduce the total ground fault current and reduce arc and flash hazards during ground faults in high voltage distribution systems.