L'augmentation du nombre de fonctions électriques disponibles dans les systèmes embarqués amène de nouvelles contraintes d'encombrement et de masse de leurs alimentations. Pour adresser ces problèmes, la miniaturisation et l'intégration des convertisseurs statiques sont donc des thématiques importantes de recherche qui aboutissent à de nombreuses évolutions technologiques et structurelles dont l'apparition de convertisseurs statiques à fréquence de fonctionnement élevée permettant la réduction des éléments passifs du convertisseurs.Ces avancées s'accompagnent cependant d'une augmentation des niveaux de perturbations électromagnétiques générés par le système. Afin de les diminuer, l'insertion de filtres CEM dans le système est nécessaire. Leurs performances sont fortement liées au contrôle de leurs éléments parasites. Les modèles développés jusqu'à présent concernent pour la plupart les effets conduits et l'évaluation de l'impact des phénomènes rayonnés est souvent ignoré ou au mieux basé sur des modèles simplistes. Un des objectifs de cette thèse est donc d'apporter un degré de complexification plus élevé des modèles de rayonnement des composants magnétiques utilisés dans les filtres CEM, tant par une approche par modélisation numérique que par la mise en oeuvre d'un modèle analytique.Dans un premier temps, une étude poussée du rayonnement magnétique de composants simples, les inductances toriques de mode différentiel, a été réalisée. Cette étude a débouché sur la mise en évidence des paramètres critiques déterminant la topologie du champ magnétique rayonné dans l'environnement proche du composant. Le résultat majeur de cette étude est l'importance de la répartition du bobinage autour du circuit magnétique sur le champ magnétique rayonné. De nouveaux modèles ont été proposés pour permettre la prédiction des champs proches rayonnés pour une gamme de fréquence inférieure à la résonance propre du composant.Par la suite, un modèle analytique fin du rayonnement magnétique des inductances de mode commun a été proposé. Ce modèle permet de déterminer \emph{a priori} le rayonnement magnétique proche du composant. Les études menées par la suite ont permis de relier les effets observés en rayonné au phénomènes conduits qui apparaissent dans ces composants notamment pour expliquer certains effets de transfert de mode (commun/différentiel).Dans une dernière partie, une étude de ces composants en susceptibilité électromagnétique (EM) a été menée. Elle a permis de rendre compte de l'influence d'une onde incidente de champ magnétique sur les composants étudiés et de valider les modèles proposés via une approche basée sur la réciprocité EM: la direction privilégiée de rayonnement est aussi celle de couplage facile pour un champ magnétique externe. / The number of electronic devices in embedded systems is constantly increasing and their contribution to volume and weight is a major concern. In order to solve these issues, a large research effort is devoted to volume reduction and power converters' integration. This lead to constant technological evolution including the appearance of high frequency power electronic converters allowing the reduction of the volume of passive components.However, due to the increase of operating frequencies and the minimization of inter-components distances, the electromagnetic radiations generated by these systems become more important. In order to decrease this interference, EMI filters are often necessary. Their performances are often related to the value of parasitic elements in the filter which must therefore be controlled. Nonetheless most of the existing models focus on conducted electromagnetic interference (EMI) and the impact of radiated phenomena is often ignored or greatly simplified. This work will therefore focus on developing highly accurate radiation models for magnetic components commonly used in EMI filters using both numeric and analytic tools.First, the magnetic fields radiated by differential mode (MD) toroidal coils, which belong to the basic magnetic components, will be thoroughly studied. This study highlighted the critical parameters determining the near-field topology. The main result is the discovery of the impact of the winding's layout around the magnetic core on the radiated magnetic field. New models have been developed in order to predict the radiated near field.Then, an accurate analytic model of the the magnetic radiation of common-mode (CM) chokes has been developed. It allows the prediction of the magnetic near-field. The application of the model lead to the correlation between radiated phenomena and conducted effects existing in these components. The importance of the winding on CM to DM mode coupling has therefore been highlighted.Finally, the electromagnetic (EM) susceptibility of these components has been studied. This work describes the influence of an external magnetic field on the components and validates the radiation models developed using the principle of EM reciprocity. It has been shown that the easy directions are the same for both the radiated and the coupled phenomena.

Noise pollution threatens marine ecosystems, where animals rely heavily on sound for navigation and communication. The largest source of underwater noise from human activity is shipping, and propeller-induced cavitation is the dominant source of noise from ships. Mitigation strategies require accurate methods for predicting cavitation-induced noise, which remains challenging. The present thesis explores prediction and modelling strategies for cavitation-induced noise from marine propellers, and provides insight into models that can be used both during propeller design and to generate intelligent vessel control strategies. I examined three distinct approaches to predicting cavitation-induced noise, each of which is discussed in one of the three main chapters of this thesis: a high-fidelity computational fluid dynamics scheme, a parametric mapping procedure, and the use of field measurements. Each of these three chapters presents different insight into the acoustic behaviour of cavitating marine propellers, as well both real and potential strategies for mitigating this critical environmental emission. A combined experimental and numerical study of noise from a cavitating propeller, focused on both the fundamental importance of experimental findings and the effectiveness of the numerical modelling strategy used, is detailed in the first main chapter of this thesis. The experimental results highlighted that loud cavitation noise is not necessarily associated with high-power or high-speed propeller operation, affirming the need for intelligent vessel operation strategies to mitigate underwater noise pollution. Comparison of the experimental measurements and simulations revealed that the simulation strategy resulted in an over-prediction of sound levels from cavitation. Analysis of the numerical results and experiments strongly suggested that the cavitation model implemented in the simulations, a model commonly used for marine propeller simulations, was responsible for the over-prediction of sound levels. Ships are powered primarily by combustion engines, for which it is possible to generate "maps" relating the emission of pollutants to the engine’s speed and torque; the second main chapter of this thesis presents the methodology I developed for generating similar "maps" relating the level of cavitation-induced noise to the speed and torque of a ship's propeller. A proof-of-concept of the method that used the model propeller from the first main chapter is presented. To generate the maps, I used a low-order simulation technique to predict the cavitation induced by the propeller at a range of different speed and torque combinations. A pair of semi-empirical models found in the literature were combined to provide the framework for predicting noise based on cavitation patterns. The proof-of-concept map shows a clear optimal operating regime for the propeller. The final main chapter of this thesis presents an analysis of field noise measurements of coastal ferries in commercial operation, the data for which were provided by an industrial partner. The key finding was the identification of cavitation regime changes with variation in vessel speed by their acoustic signatures. The results provide a basis for remotely determining which vessels produce less noise pollution when subject to speed limits, which have been implement in critical marine habitats, and which vessels produce less noise at a specific optimum speed. / Graduate

京都大学 / 新制・課程博士 / 博士(理学) / 甲第23454号 / 理博第4748号 / 新制||理||1681(附属図書館) / 京都大学大学院理学研究科地球惑星科学専攻 / (主査)准教授 伊藤 喜宏, 准教授 宮澤 理稔, 教授 久家 慶子 / 学位規則第4条第1項該当 / Doctor of Science / Kyoto University / DGAM

This doctoral thesis deals with EMC pre-compliance testing of radiated disturbance. The thesis summarizes present pieces of knowledge about restricting of disturbing ambient signals and focuses on restricting of test site imperfection influence on the measurement results. Pre-compliance test site “calibration” uses comparison signal sources. There were added up the recommendations for “calibration” steps, too. The semi-anechoic vs. fully-anechoic chambers measurements results were compared. Some methods for dealing with ambient disturbing signals were discussed and high attention was applied to the test site choice and the minimal dimension geometry was recommended. There are presented recommendations for pre-compliance radiated disturbance measurements in the conclusion with the stress on available test equipment.

As demand for 5G networks increase, so does the development of network products. In-house testing is essential during the development stage as it enables faster product releases. A part of in-house testing is the product verification stage that includes electromagnetic compatibility (EMC) tests. These tests ensure that the equipment will not disturb or be disturbed by electric field from itself or other equipment in its vicinity. One of these tests includes function testing of the product in an incident electromagnetic field, called radiated immunity. To perform this test a certain test equipment setup is needed, consisting of a signal generator, amplifier and antenna. It is the antenna that radiates this invisible electromagnetic field that can only be measured with a field probe. Measurements have to be performed in order to define an uniform field area (UFA) in which the incident electromagnetic field is applied to the equipment under test (EUT). The purpose of the thesis is to develop the radiated immunity operation test procedures and test equipment in order for Ericsson to obtain full in-house EMC testing. Firstly, a theoretical review was conducted on EMC testing standards and procedures. Followed by a theoretical assessment of the current test equipment. Experimental measurements were conducted to validate theory and determine the optimal placement of the test equipment. The outcome of the thesis is a fully operational in house test setup for radiated immunity 1–10 GHz as well as test instructions that were written on how to perform this test. So that Ericsson can perform all EMC product verification tests during the design stage of their network products. Key words 5G, internet, network, electromagnetic compatibility, EMC, radiated immunity, test, standard, equipment.

In the past few decades, on-board electronic devices have been developingtremendously in automotive industry, and it is believed that the trendof electrication and autonomous driving will sustain in the near future.Thus, passenger cars are going to suer from more severe electromagneticenvironment, especially from an EMC's perspective.This thesis is an investigation and overview on a possible simulationmethod applied to vehicle radiated immunity test in accordance withISO 11451-2 standard. The preliminary work of geometry clean-up onthe model obtained from structural dynamics department and the overallmethod development have been discussed. The main contribution of thisthesis is to build up a feasible workow that is suitable for vehicle EMCsimulations based on FEM electromagnetic simulation software ANSYSHFSS. In addition, some potential future work within this area is alsosuggested by the author. / Under de senaste decenniernas gång har elektroniken inom bilindustrinsett en kraftig utveckling, och att trenden pekar på batteridrivna och självkörande bilar som en trolig verklighet inom en snar framtid. Den utvecklingen kan också leda till att personbilar kan drabbas i en alltmer elektro-magnetisk omgivning, speciellt från EMC’s perspektiv.Denna uppsats har som syfte att undersöka och skapa en överblick genom en simulering som utfärdar ett strålningsimmunitets-test på ett fordon i enlighet med standarden ISO 11451-2. Det preliminära arbetet med geometri rening på modellen som erhållits från avdelningen för strukturdynamik och den övergripande metodutvecklingen har diskuterats. Det som med denna uppsats avser att bidra med i huvud-del är att bygga upp ett möjlig arbetsflöde som lämpar sig för EMC-simuleringar för fordon med FEM elektro-magnetiska simulations-mjukvaran ANSYS HFSS. Vidareställs frågor för ytterligare arbete och forskning av uppsats-författaren.

This thesis develops a novel method to predict radiated emissions measurements. The techniques used are based on standard Electromagnetic Compatibility (EMC) qualification test methods. The empirical data used to formulate the final results was restricted to pertinent data protocol waveforms however the entire method may be applied to any waveforms for which empirical radiated emissions have been measured. The method provides a concise means for predicting worst case radiated emissions profiles based on empirical measured data.

Examination of seismic records during the time interval of the Sago Mine disaster in 2006 revealed a small amplitude signal possibly associated with an event in the mine. Although the epicenter of the signature was located in the vicinity where the explosion occurred, it could not be unequivocally attributed to the explosion. More needs to be understood about the seismicity from mine explosions in order to properly interpret critical seismic information. A seismic monitoring system located at NIOSH's Lake Lynn Experimental Mine has monitored nineteen experimental methane and dust based explosions. The objective of the study was to analyze seismic signatures generated by the methane and dust explosions to begin understanding their characteristics at different distances away from the source. The seismic signatures from these different events were analyzed using standard waveform analysis procedures in order to estimate the moment magnitude and radiated seismic energy. The procedures used to analyze the data were conducted using self-produced programs not available with existing commercial software. The signatures of the explosions were found to be extremely complex due a combination of mine geometry and experimental design, both of which could not be controlled for the purposes of the study. Geophones located approximately 600 m (1970 ft) and over from the source collected limited data because of the attenuation of the seismic waves generated by the methane explosion. A combination of the methods used to characterize the seismic signatures allowed for differentiation between experimental designs and the size of the explosion. The factors having the largest impact on the signatures were the mine geometry, size of the methane explosion, construction of the mine seal and location of the mine seal. A relationship was derived to correlate the radiated seismic energy to the size of the explosion. Recommendations were made, based upon the limitations of this study, on methods for better collection of seismic data in the future. / Ph. D.

The aim of the work reported in this thesis is to establish a generic approach for the study of the propagation of higher-order modes in ducts of circular cross section when a simple aperture device is installed in the duct. Additionally to describe the effects of the simple aperture device on the whole in duct acoustic field, especially in the frequency range after the first higher-order mode cuts on. The approach, which is based on approximating each higher-order mode as an uncoupled mode, requires an accurate and effective decomposition of the in duct field in the higher frequency range. In the theoretical work for the propagation of the higher-order modes in circular ducts, one established model to describe the open end of the duct is considered. Another model to describe the sound source (both plane wave source and point source) and the boundaries between the aperture device and the main duct is proposed. Combining the two models together, a revised model to describe the whole acoustic system is obtained and used to carry out the in duct field decomposition in the higher frequency range. From this the amplitudes of various higher-order modes are obtained. Experimental investigations have also been carried out to determine the applicability of this model. The experimental work can be divided into two groups: reference measurements for the inputs to the models and direct measurements of the sound fields. The reference measurements are used to obtain the strength of the sound source. The direct measurements are used to compare with the results obtained from the theoretical calculations. Through the comparison, the errors and the applicability of the theoretical model are established. It is shown that this approach to the problem may be used in the normalized wave number region up to k * R -< 7 , which is nearly four times the plane wave region and includes sixteen propagating higher-order modes. By determining the amplitudes of the higher-order modes, the whole in-duct acoustic field is fully decomposed into individual model contributions and can be reconstructed in detail. In order to get a complete and coordinate-independent description of the effects of installing different simple aperture devices, the power radiated out of the open end of - i - the duct is calculated in the fonn of different single modes. Additionally the insertion losses for different aperture device situations are also obtained. Then through the comparison of the powers and the insertion losses, it is possible to find an effective and direct way to express the effects of installing different simple aperture devices in a duct.

In dieser Arbeit wird das Verhalten der Störstrahlung großer Prüflinge untersucht mit dem Ziel, vorhandene Standards für Störstrahlungstests wie CISPR 16 zu verbessern. Diese Arbeit sieht als Standardtestumgebung einen reflektierenden, ausgedehnten Grund vor, auf dem sich der Prüfling befindet. Die Strahlung, die dieser aussendet, wird durch die Verteilung der elektrischen Feldstärke auf einer Testhalbkugel oberhalb des Grunds bewertet. Ihr Zentrum befindet sich am Fußpunkt des Prüflings. Eine solche Halbkugel stellt nahezu gleiche Abstände von etwa der Länge des Kugelradius' zwischen dem Prüfling und den auf ihr definierten Meßpunkten her. Da die Halbkugel geschlossen ist, kann auf ihr das gesamte vom Prüfling nach außen gestrahlte Feld nachgewiesen werden. Meßabstände mit in Normen vorgegebenen Längen sind in der Praxis nicht immer einzuhalten, vor allem dann, wenn sich Prüflinge in einer normalen Betriebsumgebung befinden. In beengten Umgebungen ist es hilfreich, Meßabstände zu verkürzen. Hieraus ergibt sich eine kleinere Testhalbkugel, die sich leichter abtasten läßt. Bei kurzen Meßabständen jedoch können Meßsonden in das Nahfeld des Prüflings ragen. Für diesen Fall werden in dieser Arbeit Feldeigenschaften in Prüflingsnähe untersucht. Aus denen ergeben sich Mindestabstände zum Prüfling, jenseits derer sich gemessene Feldstärkewerte zu größeren, in Normen vorgegebenen Abständen extrapolieren lassen. Um die Verteilung der Feldstärke auf einer Testfläche zu beschreiben, wird der Begriff der Halbwertsfläche eingeführt: Die Halbwertsfläche definiert jenen Teil der Testfläche, auf dem die Dichte der abgestrahlten Leistung mindestens die Hälfte ihres Maximums beträgt. Die Halbwertsfläche ergibt sich aus der Richtwirkung des Prüflings als Strahler. Sie ist somit ein Maß für die Wahrscheinlichkeit, auf der Testfläche das Strahlungsmaximum zu finden. Aus der Größe der Halbwertsfläche ergibt sich die nötige Anzahl an gleichmäßig auf der Testfläche verteilten Meßpunkten, um das Strahlungsmaximum mit gegebener Wahrscheinlichkeit zu finden. Wird an den Meßpunkten die Größe der Feldstärke berücksichtigt, läßt sich die Anzahl der Meßpunkte optimieren und das Vertrauen in den Test erhöhen. Als ein erster Schritt zur Entwicklung einer praktikablen Strahlungstestmethode wird die Testdrahtmethode untersucht. Bei dieser Methode wird Strahlung mit einem langen, um den Prüfling herum gespannten Draht erfaßt. Die Strahlung induziert in dem Draht einen Strom, der an den Drahtabschlüssen gemessen werden kann. Weil der Draht i. allg. lang ist, ist er sehr meßempfindlich. Ist er jedoch länger als eine Wellenlänge des abgestrahlten Felds, sind sein Übertragungsfaktor und damit die Meßergebnisse schwer zu bestimmen. Statistische Methoden der Auswertung werden hierzu untersucht. Ein System aus kleinen Meßsonden kann denselben Teil des Prüflings abdecken wie ein Testdraht. Weil als Übertragungsfaktor eines solchen Systems der einer Einzelsonde wirksam ist, lassen sich Ergebnisse aus Messungen mit einem solchen System leichter auswerten. Jedoch ist die Empfindlichkeit kleiner Sonden i. allg. gering. Der Weg zu einer praktischen Anwendung führt somit vorerst in die Richtung herkömmlicher Meßantennen, die in einem beweglichen System geeignete Testflächen abtasten. - (Die Dissertation ist veröffentlicht im Jörg Vogt Verlag, Dresden, Deutschland, http://www.vogtverlag.de, ISBN: 978-3-938860-25-0) / In this work the behavior of radiation emitted by large equipment is investigated. The aim of investigation is to improve existing standardized radiation tests. The radiation from an EUT (equipment under test) placed on reflecting ground is described by the distribution of the electric field strength on a hemispheric test area, which encloses the EUT placed in its center. This kind of area guarantees a nearly equal measurement distance to the EUT from every point defined on it. This distance is defined by the radius of the hemisphere. However, measurement distances according to standards are difficult to realize. Because of practical constraints shorter distances will become useful. This requires a smaller test area, to be scanned more easily. At shorter measurement distances field probes are possibly located in the near field of the EUT. Therefore this work investigates the behavior of the field in the vicinity of the EUT to find an adequate transition point, beyond which, field strength values can be extrapolated to distances instructed by standards with confident results. An important parameter of the field strength distribution is the half-power area. It defines that part of the test area where the radiated power exceeds the half of its maximum. The half-power area is related to the directivity of the EUT, which can be approximated by antenna theory or statistics. If the directivity of the EUT is high, the half-power area is small, and the probability to find the field maximum on the test area is low. The size of the half-power area yields to a least number of observation points, equally distributed on the test area, to find the field maximum with a high level of confidence. If the field strength measured at any observation point is considered, the distance to other observation points can be optimized, and the level of confidence in the test can be increased. As a first step in developing a practicable field scanning method is highlighted: the test wire method. This method establishes a measurement executed by a long wire which covers the EUT. At its terminations current can be measured induced by the radiation. Because the wire is long it is very sensitive. However, if it is longer than one wave length of the radiation, the evaluation of results is difficult because of an uncertain transmission factor. Therefore, some statistic methods are applied to describe the behavior of results and their maxima. Also a system of small probes, e. g. short dipoles, can cover the same part of the EUT as a test wire. The measurement with small probes can be evaluated more easily because of a unique transmission factor. However, their sensitivity is lower.