Owing to the ever-changing developments of battery and electric powertrain, vehicle electrification is the trend in the future. Without the presence of a combustion engine, masking effect from it reduces and noises from other components become perceivable. Among all, the cooling fan is one of the major noise sources. The design of cooling fan modules is usually carried out in the early stage before building prototype vehicles. Therefore, it is essential to come up with a method for selecting optimal fan design without performing complete vehicle testing. This is a Master's degree project in collaboration with Volvo Cars, with a focus on cooling fan noise at the charging state of electric vehicles. The main objective of this thesis is to understand the effects of fan installation. Three different setups of acoustic measurement are carried out, namely free-space, wall-mounted, and in-vehicle measurement. Correlations of these measurements are investigated through comparisons of the measurement results and the installation effects are identified through spectrum difference between free-space and in-vehicle measurement. Moreover, the implementation of spectral decomposition method enables the separation of source strength and propagation effect. Analyses of sound pressure levels are studied by looking into tonal and broadband components. In addition, sound power levels are determined by following ISO standards. Finally, a subjective rating session is held to understand the human perception of cooling fan noise. / Med anledning av den pågående utvecklingen mot elektrifiering där bilarna går mot batterier och elmotorer för framdrivning så ändras ljudbilden. Utan förbränningsmotorer som tidigare maskerade mycket av ljudet från bilarna så framträder nya ljudkällor. En sådan är kylfläkten som allt mer blir en störningskälla. Vanligtvis sker designen av kylfläktsmodulen i en tidig fas innan det finns någon prototypbil att tillgå. Detta gör att det är viktigt att utveckla metoder för att i tidig fas kunna optimera designen av kylfläkten.  Detta är ett examensarbete i samarbete med Volvo Cars med fokus på det ljud som uppstår vid laddning av eldrivna bilar. Uppsatsens huvudsakliga mål är att förstå fläktinstallationens påverkan på ljud genom att korrelera olika typer av mätningar. Detta genomfördes m.h.a tre separata konfigurationer, fritt-upphängd mätning, väggmonterad och installerad i bil. Korrelation undersöktes genom att jämföra mätresultat och analys av spektrumet. Analysen av ljudtrycksnivåerna genom att titta på dels de tonala komponenterna men också på bredbandsnivåerna. Utöver detta fastställs även ljudeffekten genom att följa gängse ISO standard. Slutligen så gjordes en subjektiv utvärdering för att få en förståelse av upplevelsen av ljudet från en kylfläkt.

Yes / Satellite QKD/FSO systems, which facilitate quantum key distribution (QKD) over free-space optical (FSO) links between satellites and ground stations, present a promising pathway toward achieving global security in upcoming sixth-generation (6G) wireless communications. Our study focuses on a superior type of these systems, the satellite EB/CV-QKD/FSO, which utilizes the continuous-variable (CV) method for quantum state representation and the entanglement-based (EB) scheme for QKD implementation. We propose the use of optical phase-shift keying (QPSK) signaling and dual-threshold/heterodyne detection (DT/HD) receivers to bolster the reliability and feasibility of satellite EB/CV-QKD/FSO systems. Closed-form expressions for key system performance metrics are derived using improved channel modeling. Numerical results are presented to showcase the effects of channel impairments on the system performance. We also provide recommendations for optimal system setup parameters, aiming to enhance performance. / Ministry of Information and Communications (Vietnam) (Grant Number: DT.26/23). Asia Pacific Network Information Centre (APNIC) Foundation under the Switch! Project

[pt] Este trabalho apresenta o estudo de comunicação óptica quântica no infravermelho, utilizando um sistema híbrido fibra-óptica – espaço-livre, como prova de princípio para o estabelecimento de chaves secretas a fim de utilização em criptografia do tipo one-time pad. Ao modular a polarização da luz de um laser em polarizações ortogonais, podem-se codificar os bits clássicos 1 e 0 em cada uma dessas polarizações, sendo detectadas por detectores contadores de fótons únicos, e, assim, utilizar o canal quântico para transmissão dos bits quânticos entre dois interlocutores, utilizandoos para o estabelecimento da chave criptográfica, que pode ser usada em qualquer tipo de informação a ser transmitida por um canal clássico ou quântico. Ao realizar a transmissão em espaço-livre, sujeita a variações climáticas, como temperatura atmosférica, luz solar, presença de nuvens, chuva e vento, foi também estudada a influência destes fenômenos na qualidade da transmissão e dos dados obtidos. Os resultados experimentais demonstraram consistência com a teoria e com outros trabalhos publicados na área até esta data com relação às taxas de erro de bit quântico e também à taxa de transmissão de bits. As taxas de erro obtidas, por estarem abaixo do limiar teórico para segurança da informação em comunicação quântica, provam, ainda, a possibilidade de estabelecimento de chave secreta para criptografia através do uso de distribuição quântica das chaves (QKD). Os resultados também apresentaram boa qualidade da informação recuperada após a descriptografia. / [en] This work presents the study of optical quantum communication in the infrared region, using a hybrid optical-fiber – free-space system, as proof of principle for the agreement on secret keys by two parties for use in one-time pad encryption. By modulating the polarization of laser light into orthogonal polarizations, one can encode the classic bits 1 and 0 in each of these polarizations, being detected by single photon counter detectors, and can use the quantum channel to transmit the quantum bits between two interlocutors. It is then possible to use those bits to establish the cryptographic key, which can be used in any type of information to be transmitted by a classic or quantum channel. While carrying out transmission in free space optics, subject to climatic variations, such as atmospheric temperature, sunlight, presence of clouds and rain, and the presence of wind, the influence of these phenomena on the quality of transmission and on the data obtained was also studied. The experimental results showed consistency with the theory and with other works published to date with regard to quantum bit error rates and to the bit rate. The error rates obtained, being below the theoretical threshold for information security in quantum communication, further proves the possibility of establishing a secret key for encryption through the use of quantum key distribution (QKD). It also presented good quality on the information recovered after decryption.

Cette thèse porte sur la caractérisation non destructive de structures 2D magnéto-diélectriques inhomogènes complexes. L’ensemble des étapes allant de l’expérience au traitement du problème inverse est traité. Dans un premier temps, un modèle direct reliant le champ diffusé aux propriétés électromagnétiques du matériau a été mis en place. Ce modèle requiert des calculs par éléments finis de la propagation de l’onde électromagnétique, en présence de l’objet observé lorsque celui-ci est positionné sur un support métallique. Une validation expérimentale a été réalisée via la mise en place d'un banc de mesure multi statique. Différentes étapes d'ajustements et d'étalonnages ont permis la réduction du bruit de mesure ainsi que des biais. L’inversion est traitée principalement par une approche linéaire, avec un choix attentif de la valeur des hyper paramètres qui y sont associés. Une fois les outils mis en place, six études ont été réalisées pour la validation de notre système d’imagerie 2D des propriétés électromagnétiques de matériaux magnéto-diélectriques inhomogènes. Cela comprend l’évaluation des incertitudes de mesure, de la résolution spatiale, la mesure de différents matériaux magnétiques et l’utilisation de différents supports à géométries variées. L’ensemble des résultats expérimentaux réalisés se place dans une hypothèse de géométrie 2D. C’est pourquoi, nous avons ensuite orienté nos travaux vers la recherche d’un design innovant permettant de faire évoluer le banc de mesure en un dispositif d’imagerie 3D. Dans cette perspective, une source secondaire vient se déplacer proche de la cible pour acquérir de l’information selon la troisième dimension. / The subject of this thesis is the non-destructive characterization of complex inhomogeneous magneto-dielectric structures. Successively, the experimental developments, the modelling and the data treatments stages are addressed. A forward model that links the scattered field to the electromagnetic properties is established. This model requires some finite element computations in order to estimate the propagation of the electromagnetic wave in presence of the magneto-dielectric object which is glued on a metallic support. A multistatic bench has been designed and constructed in order to collect measured scattered fields. Several adjustments and calibration procedures have been carried out to reduce the measurement noise and biases. Next, the inverse problem has been dealt with, in order to retrieve the electromagnetic properties of the samples, from the measured scattered field. The inverse problem is mainly solved with a linear approach, with a careful selection of the hyperparameters. Once the system has been fine tuned, six studies have been realized to validate our 2D imaging system. The assessment of the measurement uncertainty, the evaluation of the spatial resolution, the characterization of various magnetics materials and the use of different supports with variable geometries have been performed. So far, all the developments were done under a 2D hypothesis. That is why, we have then focused our research on the design of a 3D innovative imaging setup. To this end, a secondary source moving close to the target has been added in order to gain information in the third direction. A numerical study has been performed to assess the expected performances of this new setup.

We present robust explicit construction of 3D configuration spaces using controlled linear perturbation. The input is two planar parts: a fixed set and a moving set, where each set is bounded by circle segments. The configuration space is the three-dimensional space of Euclidean transformation (translations plus rotations) of the moving set relative to the fixed set. The goal of constructing the 3D configuration space is to determine the boundary representation of the free space where the intersection of the moving set and fixed set is empty. To construct the configuration space, we use the controlled linear perturbation algorithm. The controlled linear perturbation algorithm assigns function signs that are correct for a nearly minimal input perturbation. The output of the algorithm is a consistent set of function signs. This approach is algorithm-independent, and the overhead over traditional floating point methods is reasonable. If the fixed and moving sets are computer representations of physical objects, then computing the configuration space greatly aids in many computational geometry problems. The main focus of computing the configuration space is for the path planning problem. We must find if a path exists from the start to the goal, where the fixed set is the obstacle, and the moving set is the object trying to reach the goal.

No description available.

Made available in DSpace on 2014-12-17T15:48:12Z (GMT). No. of bitstreams: 1 LeonardoDO_DISSERT.pdf: 3357434 bytes, checksum: 75c2c837997e2220e8de164c844c9b5d (MD5) Previous issue date: 2014-06-05 / Due to the constantly increasing use of wireless networks in domestic, business and industrial environments, new challenges have emerged. The prototyping of new protocols in these environments is typically restricted to simulation environments, where there is the need of double implementation, one in the simulation environment where an initial proof of concept is performed and the other one in a real environment. Also, if real environments are used, it is not trivial to create a testbed for high density wireless networks given the need to use various real equipment as well as attenuators and power reducers to try to reduce the physical space required to create these laboratories. In this context, LVWNet (Linux Virtual Wireless Network) project was originally designed to create completely virtual testbeds for IEEE 802.11 networks on the Linux operating system. This paper aims to extend the current project LVWNet, adding to it the features like the ability to interact with real wireless hardware, provides a initial mobility ability using the positioning of the nodes in a space coordinates environment based on meters, with loss calculations due to attenuation in free space, enables some scalability increase by creating an own protocol that allows the communication between nodes without an intermediate host and dynamic registration of nodes, allowing new nodes to be inserted into in already in operation network / Com o crescimento constante da utiliza??o de redes sem fio em ambientes dom?sticos, empresariais e at? industriais, aparecem novos desafios. A prototipa??o de novos protocolos nesses ambientes tipicamente ? restrita a ambientes de simula??o, onde existe a necessidade de uma dupla implementa??o, uma no ambiente de simula??o, onde se realiza uma prova de conceito inicial e outra em um ambiente real. Al?m disso, uma vez que se parta para ambientes reais, n?o ? trivial a cria??o de um testbed para redes sem fio de alta densidade, dada a necessidade de uso de v?rios equipamentos reais, e uso de atenuadores, redutores de pot?ncia, para tentar reduzir o espa?o f?sico necess?rio para cria??o desses laborat?rios. Nessa lacuna, o projeto LVWNet (Linux Virtual Wireless Network) foi inicialmente concebido para cria??o de testbeds completamente virtuais para redes IEEE 802.11 sobre o sistema operacional Linux. Este trabalho tem como objetivo extender o atual projeto LVWNet adicionando a ele os recursos de possibilitar a intera??o com hardwares wireless reais, dar um suporte inicial ? mobilidade atrav?s do posicionamento dos n?s em um ambiente de coordenadas no espa?o baseado em metros, j? com c?lculos de perda decorrente da atenua??o em espa?o livre, aumentar a escalabilidade com a cria??o de um mecanismo que permita a comunica??o direta entre os n?s sem necessidade de um host intermedi?rio al?m do registro din?mico de n?s, de modo que novos n?s podem ser inseridos na rede com a mesma j? em opera??o

Le travail de cette thèse est consacré à l’étude et l’optimisation d’un cas particulier de la diffusion des ondes électromagnétiques. Elle porte plus particulièrement sur un phénomène appelé le « jet photonique ou jet électromagnétique (jet EM)». Il s’agit d’un faisceau de lumière étroit et concentré en champ proche avec des caractéristiques physiques remarquables. Dans ce travail, un guide d’onde terminé par un embout de forme particulière est utilisé pour générer le jet photonique. Cette thèse a pour objectif l’étude, la caractérisation expérimentale et l’optimisation de jets photoniques pour des applications dans le domaine optique et hyperfréquences. Une méthode robuste et rapide a été développée pour calculer le champ électromagnétique généré par un objet diélectrique ou en sortie d’un guide d'onde avec un embout de forme particulière. Elle est basée sur la Méthode d'Equation Intégrale aux Frontière (MEIF) qui utilise la seconde identité Green. La caractérisation expérimentale des jets photoniques a été réalisée dans le domaine micro-ondes à des fréquences autour de 30 GHz. La possibilité de générer un jet simple et double en utilisant un guide d’onde à embout a été montrée expérimentalement et théoriquement par la méthode MEIF. Les jets EM simples et doubles ont été utilisés pour la détection d’objets métalliques de taille plus petite que la longueur d’onde et l'imagerie en champ proche à travers des structures optiquement opaques. Une procédure d’optimisation basée sur le couplage entre la MEIF et les algorithmes génétiques a été mise au point afin de générer des jets photoniques avec des caractéristiques a priori bien définie. Des optimisations des jets photoniques générés par un objet diélectrique et en sortie d’un guide d’onde avec embout ont été effectuées pour la micro-gravure laser et l’imagerie HF / The work of this thesis is devoted to the study and optimization of a particular case of the scattering of electromagnetic waves. Particularly, it is about a phenomenon called the "photonic jet or electromagnetic jet (EM jet)". This is a narrow light beam concentrated in near-field with remarkable physical characteristics. In this work, a waveguide terminated by a tip with special form is used to generate the photonic jet. This thesis performs the electromagnetic modeling, the experimental characterization and the optimization of photonic jets for applications in optic and microwave field. A robust and fast method was developed to calculate the electromagnetic field generated by a dielectric object or by a waveguide terminated with a tip. It is based on the boundary integral equation method (BIEM) which uses the second Green identity. Experimental characterization of photonic jets was conducted in the microwave field around 30 GHz. The ability to generate a single and double EM jet using a tipped waveguide has been shown experimentally and theoretically by BEIM method. The single and double EM jets were used for the detection of metal objects with a size smaller than the wavelength and for imaging through opaque structures in near field. An optimization procedure based on the coupling between the BEIM and genetic algorithms has been developed to generate photonic jets with properties well defined. Optimizations of photonic jets generated by a dielectric object and by a tipped waveguide have been realized for laser micro-etching and RF imaging

[ES] Las comunicaciones ópticas inalámbricas (OWC) constituyen una tecnología muy prometedora para el desarrollo de futuras comunicaciones inalámbricas. De hecho, ha despertado un interés creciente entre los investigadores y varias empresas de todo el mundo trabajan actualmente en el desarrollo de redes inalámbricas de muy alta velocidad. Las comunidades científica e industrial consideran la OWC como una tecnología complementaria en sus diversas formas: comunicaciones ópticas en el espacio libre (FSO), comunicaciones de luz visible (VLC) o fidelidad de la luz (Li-Fi). El espectro óptico ha sido considerado durante muchos años como una gran oportunidad para las comunicaciones inalámbricas, especialmente debido a la saturación del espectro de radiofrecuencia (RF). Esta disertación trata del uso de fuentes de banda ancha en sistemas de transmisión de luz visible (VLC), así como en sistemas de transmisión en el espectro infrarrojo por fibra óptica. En el trabajo de investigación realizado se pueden distinguir tres partes: En la primera parte, se considera el estudio y la simulación de componentes de Diodos Emisores de Luz (LED) con el software WIEN2k centrándose en las propiedades ópticas y eléctricas de los elementos II-VI. La segunda parte trata del diseño, la implementación y las pruebas de diferentes prototipos de comunicación VLC para la transmisión analógica y digital en modo simplex y semidúplex. Hemos demostrado un sistema OWC empleando una fuente de banda ancha (LED) para la transmisión no sólo de datos, sino también para la transmisión inalámbrica de energía. Además, se aborda el problema de la sincronización y la detección del nivel "1" o "0" de un bit en los sistemas de comunicación inalámbrica óptica implementados que surge como consecuencia de la atenuación de la luz a lo largo de la distancia y al problema de la pérdida de línea de visión (NLOS) entre el emisor y el receptor. Para hacer frente a este problema, se ha proporcionado un protocolo de comunicación que garantiza la transmisión fiable de datos digitales con un algoritmo de detección de nivel de bits adaptativo y se ha demostrado su eficacia mediante la transmisión de textos e imágenes. Además, esta tesis aporta una solución para la implementación de transmisores multiplexados en redes con división de longitud de onda (WDM) para formatos de modulación con multiplexación por división de frecuencia ortogonal (OFDM) basados en el uso de fuentes de banda ancha en el espectro infrarrojo para redes de fibra bidireccionales centralizadas. A pesar de las limitaciones impuestas por la dispersión cromática en el uso de este tipo de fuentes ópticas, la inclusión de ciertas estructuras antes de la detección permite la transmisión de señales OFDM en enlaces ópticos. En este trabajo se ha demostrado experimentalmente la reutilización de portadoras, la asignación dinámica de ancho de banda y la transmisión de señales OFDM multibanda mediante el uso de fuentes ópticas de banda ancha en redes WDM. Los principales resultados obtenidos en cada parte de esta tesis doctoral muestran los procedimientos de estudio, la eficacia de las soluciones propuestas y las limitaciones encontradas. / [CA] Les comunicacions òptiques sense fils (OWC) constitueixen una tecnologia molt prometedora per al desenvolupament de futures comunicacions sense fils. De fet, ha despertat un interés creixent entre els investigadors i diverses empreses de tot el món treballen actualment en el desenvolupament de xarxes sense fils de molt alta velocitat. Les comunitats científica i industrial consideren la OWC com una tecnologia complementària en les seues diverses formes: comunicacions òptiques en l'espai lliure (FSO), comunicacions de llum visible (VLC) o fidelitat de la llum (Li-Fi). L'espectre òptic ha sigut considerat durant molts anys com una gran oportunitat per a les comunicacions sense fils, especialment a causa de la saturació de l'espectre de radiofreqüència (RF). Aquesta dissertació tracta de l'ús de fonts de banda ampla en sistemes de transmissió de llum visible (VLC), així com en sistemes de transmissió en l'espectre infraroig per fibra òptica. En el treball de recerca realitzat es poden distingir tres parts: ¿ En la primera part, es considera l'estudi i la simulació de components de Díodes Emissors de Llum (LED) amb el software WIEN2k centrant-se en les propietats òptiques i elèctriques dels elements II-VI. ¿ La segona part tracta del disseny, la implementació i les proves de diferents prototips de comunicació VLC per a la transmissió analògica i digital de manera simplex i semidúplex. Hem demostrat un sistema OWC emprant una font de banda ampla (LED) per a la transmissió no sols de dades, sinó també per a la transmissió sense fil d'energia. A més, s'aborda el problema de la sincronització i la detecció del nivell "1" o "0" d'un bit en els sistemes de comunicació sense fil òptica implementats, que sorgeix a conseqüència de l'atenuació de la llum al llarg de la distància i al problema de la pèrdua de línia de visió (NLOS) entre l'emissor i el receptor. Per a fer front a aquest problema, s'ha proporcionat un protocol de comunicació que garanteix la transmissió fiable de dades digitals amb un algorisme de detecció de nivell de bits adaptatiu i s'ha demostrat la seua eficàcia mitjançant la transmissió de textos i imatges. ¿ A més, aquesta tesi aporta una solució per a la implementació de transmissors multiplexats en xarxes amb divisió de longitud d'ona (WDM) per a formats de modulació amb multiplexació per divisió de freqüència ortogonal (OFDM) basats en l'ús de fonts de banda ampla en l'espectre infraroig per a xarxes de fibra bidireccionals centralitzades. Malgrat les limitacions imposades per la dispersió cromàtica en l'ús d'aquest tipus de fonts òptiques, la inclusió d'unes certes estructures abans de la detecció permet la transmissió de senyals OFDM en enllaços òptics. En aquest treball s'ha demostrat experimentalment la reutilització de portadores, l'assignació dinàmica d'amplada de banda i la transmissió de senyals OFDM multibanda mitjançant l'ús de fonts òptiques de banda ampla en xarxes WDM. Els principals resultats obtinguts en cada part d'aquesta tesi doctoral mostren els procediments d'estudi, l'eficàcia de les solucions proposades i les limitacions trobades. / [EN] Optical wireless communication (OWC) is a very promising technology for future wireless communications developments. It has attracted increasing interest from researchers and several companies around the world are currently working on the development of very high-speed wireless networks. The scientific and industrial communities believe that OWC will be a complementary technology in its various forms: Free Space Optical communications (FSO), Visible Light Communications (VLC), Light Fidelity (Li-Fi). In fact, the optical spectrum has been considered for many years as a great opportunity for wireless communications especially due to the saturation of the radio frequency (RF) spectrum. This dissertation deals with the use of broadband sources in visible light transmission systems (VLC) as well as fiber optic systems. To carry out the research, three parts can be distinguished: In the first part, we consider the study and simulation of Light Emitting Diode (LED) components with the WIEN2k software by focusing on the optical and electrical properties of elements II-VI. The second part deals with the design, implementation and testing of different VLC communication prototypes for analog and digital transmission in simplex and half-duplex mode. We have demonstrated that an OWC system using a broadband source (i.e. an LED) can be used not only for data transmission, but also for wireless power transmission. Moreover, the synchronization problem and the detection of level "1" or "0" of a bit often arise in the optical wireless communication systems. This is a result of the attenuation nature of the light over the distance and the problem of Non Line-Of-Sight (NLOS) between the emitter and the receiver. To deal with this problem, a communication protocol ensuring reliable digital data transmission with an adaptive bit level detection algorithm has been provided and its effectiveness has been demonstrated by the transmission of texts and images. In addition, this thesis provides a solution for the implementation of wavelength division multiplexed - orthogonal frequency division multiplexed (WDM-OFDM) transmitters based on the use of broadband sources in the infrared spectrum for centralized bidirectional fiber networks. Despite the chromatic dispersion that avoids the use of this type of optical sources, the inclusion of certain structures before detection allows the transmission of OFDM signals in optical links. Carrier reuse, dynamic bandwidth allocation and multiband OFDM signals transmission will be experimentally demonstrated by using optical broadband sources in WDM networks. The main results obtained during this thesis work demonstrate the study procedures, for each part, the effectiveness of the proposed solutions as well as the constraints encountered. / Sekkiou, I. (2021). Design of communication systems based on broadband sources for fiber and free space optical links [Tesis doctoral]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/172542 / TESIS

This Master’s thesis analizes technologies suitable for metropolitan area networks. In this thesis there are mentioned technologies used for wireless transfer with speeds above 1 Gbps. There are described basic features and parameters of microwave radio relay links in 70/80GHz range and free space optic links. These technologies are compared with classic optical networks. Practical part of thesis was focused on development of application which calculates signal attenuation caused by the passage of the atmosphere for both technologies. Results gained from this application are mentioned in this Master’s thesis.