Aujourd'hui les réseaux de capteurs sont devenus des systèmes pouvant atteindre un très grand nombre de noeuds, avec une zone de couverture déterminée et déployés d'une manière plus ou moins dense dans un environnement hétérogène dont on mesure ainsi son état global. La problématique de cette thèse consiste à concevoir une architecture pour les objets communicants à faible consommation en utilisant des antennes « intelligentes » pour l'instrumentation et la mesure. Intégrant une approche pluridisciplinaire, cette architecture couvre les services offerts depuis les couches MAC jusqu'à celles de plus haut niveau. Basés sur une partie matérielle complètement reconfigurable (amplificateur de puissance et antennes à base de MEMS RF), les services des couches supérieures sont définis en partie sur circuits numériques pour la couche physique (bande de base) et la couche MAC, et de manière logicielle pour les protocoles de routages adaptés et les services innovants. En résumé, le travail consiste à concevoir un système autonome multi capteurs, d'acquisition et de traitement avec mémorisation, communicant à travers un réseau sans fil. Les principaux problèmes à résoudre seront : le contrôle de la topologie, la précision de la synchronisation, la consommation d'énergie. / Researches in the field of sensor networks show the variety and vastness of applications in which these types of systems are used. One of their main features is the large number (up to hundreds of elements) of sensors that must be distributed in different environments. Another concern consists in making routing decisions in order to reduce the energy consumption. Depending on the application requirements, ensuring synchronous network functionality is currently a challenge. The issue addressed in this thesis is to develop an architecture for smart objects using low-power antennas for structural heald monitoring. Integrating a multidisciplinary approach, this architecture includes services from the MAC layer to those of the highest level. In summary, we will develop an autonomous system ofi sensors, for acquisition and information processing, which communicate via a wireless network. The main problems are: the control of topology, the timing accuracy and the energy consumption.

This study is an initial attempt to investigate the possibility of substituting conventional laboratory destructive testing techniques at Sandvik's strip steel production facilities with the 3MA (Micro-magnetic Multi-parameter Microstructure and Stress Analysis) NDT (nondestructive testing) technique. The interest for the research comes from various problems with the actual destructive testing method. Sandvik manufactures thin strip steel (among other products) and controls the quality of its product by taking samples from the ends of the strip and measuring the sample's material properties in a separate laboratory. Hence, the sample preparation process is time and material consuming, and the results obtained from the laboratory measurements are not always representative of the real values along the whole length of the strip (usually several kilometers). Therefore, the present project involves the correlation between three material properties (Vickers hardness, tensile strength and carbide density) and a selection of micro-magnetic parameters measured with the 3MA-II equipment manufactured by the Fraunhofer IZFP institute. The 3MA-II system is based on four measuring techniques (harmonic analysis, magnetic Barkhausen noise, incremental permeability and Eddy current testing) and is capable of recording up to 41 micro-magnetic parameters. Samples of two different steel grades (composition) were used in the study. The results for hardness and tensile strength (average relative errors of 1.04% and 0.78%, respectively) corroborated the applicability of the 3MA technique to steel strip inspection. Thus, the implementation of this technique would lead to an improvement in the company's energy efficiency and sustainability. However, finding a good correlation between micromagnetic parameters and material properties is not always possible and, in the case of carbide density, no reliable correlation was achieved. So, further experiments are proposed for future studies regarding carbide density and other material properties.

<div>"Can machines think?", the question brought up by Alan Turing, has led to the development of the eld of brain-inspired computing, wherein researchers have put substantial effort in building smarter devices and technology that have the potential of human-like understanding. However, there still remains a large (several orders-of-magnitude) power efficiency gap between the human brain and computers that attempt to emulate some facets of its functionality. In this thesis, we present design techniques that exploit the inherent variability in the difficulty of input data and the correlation of characteristic semantic information among inputs to scale down the computational requirements of a neural network with minimal impact on output quality. While large-scale artificial neural networks have achieved considerable success in a range of applications, there is growing interest in more biologically realistic models, such as, Spiking Neural Networks (SNNs), due to their energy-efficient spike based processing capability. We investigate neuroscientific principles to develop novel learning algorithms that can enable SNNs to conduct on-line learning. We developed an auto-encoder based unsupervised learning rule for training deep spiking convolutional networks that yields state-of-the-art results with computationally efficient learning. Further, we propose a novel "learning to forget" rule that addresses the catastrophic forgetting issue predominant with traditional neural computing paradigm and offers a promising solution for real-time lifelong learning without the expensive re-training procedure. Finally, while artificial intelligence grows in this digital age bringing large-scale social disruption, there is a growing security concern in the research community about the vulnerabilities of neural networks towards adversarial attacks. To that end, we describe discretization-based solutions, that are traditionally used for reducing the resource utilization of deep neural networks, for adversarial robustness. We also propose a novel noise-learning training strategy as an adversarial defense method. We show that implicit generative modeling of random noise with the same loss function used during posterior maximization, improves a model's understanding of the data manifold, furthering adversarial robustness. We evaluated and analyzed the behavior of the noise modeling technique using principal component analysis that yields metrics which can be generalized to all adversarial defenses.</div>

A comparative study between the techniques Bluetooth Low Energy and Bluetooth Classic has been performed in cooperation with Saab AB with the purpose to determine which technique is best suited for transmission of data between an Android unit and an embedded system. The parameters that has been analyzed are throughput, energy efficiency and susceptibility. The study has been performed in accordance with the method Design Science Research and has therefore produced an artefact in the form of a system that has been evaluated in an experiment where performance parameters have been measured and analyzed. The results show that BLE is more robust in environments with a high level of noise and can handle lower SNR levels than BR/EDR; 3 dB vs 7,5 dB. If enough transfer speed is reached, BLE would also give the best energy efficiency and if the specified maximum throughput is reached, BLE would, according to this study, have more than double the energy efficiency as BR/EDR. BLE is, according to most measures, preferable from Bluetooth version 5 and is future-proof but BR/EDR still provides the highest throughput.

Les systèmes géothermiques de surface extraient l’énergie du sol via un fluide caloporteur circulant dans un échangeur pour une profondeur ne dépassant pas 200 m. Deux typologies d’échangeurs sont généralement utilisées : les systèmes avec échangeurs verticaux, principalement affectés par les conditions géologiques ; et les échangeurs horizontaux, plus proches de la surface du sol, impactés essentiellement par les conditions climatiques. Dans le sol, les échanges thermiques sont majoritairement des transferts de chaleur par conduction. Ainsi, les propriétés thermo-physiques du sol influencent la quantité d’énergie extraite par les échangeurs. Afin de quantifier les propriétés thermo-physiques d’un sol sous l’influence des conditions géologiques et climatiques, deux dispositifs expérimentaux sont élaborés, conçus, instrumentés et validés au sein de notre laboratoire. Les résultats expérimentaux enrichissent les connaissances scientifiques sur le comportement hydrique d’un sol soumis à des événements pluvieux et l’impact de la contrainte verticale sur les propriétés thermo-physiques d’un sol. De plus, une étude numérique, à partir d’une modélisation 2D par éléments finis d’un échangeur airsol, évalue les performances énergétiques de ce dernier en fonction de différentes humidifications du sol et différents scénarios de pluie. Les résultats numériques révèlent ainsi l’intérêt d’utiliser un sol d’enrobage très humide pour accroître significativement les performances énergétiques d’un échangeur air-sol. / Surface geothermal systems extract energy from the ground via a fluid circulating in an exchanger at a depth not exceeding 200 m. Two typologies of exchangers are generally used: systems with vertical exchangers, mainly affected by geological conditions; and horizontal exchangers, closer to the surface of ground, impacted mainly by weather conditions. Thermal exchanges in the soil are mainly conduction heat transfers. Thus, thermo-physical properties of soil influence, mostly, energy extracted by exchangers. In order to quantify influence of geological and meteorological conditions on thermo-physical properties of soil, two experimental devices are developed, designed, instrumented and validated. The experimental results provide more appropriate scientific knowledge on hydric behavior of a soil subjected to rain events and influence of compactness on thermal properties of soil. In addition, one numerical study, based on a finite element 2D modeling of an earth-air heat exchanger, evaluates their energy performance under different soil moisture conditions and rain scenarios thus revealing the utility of water to significantly improve its performance.

This study try to understand which aspects were fundamental to indoor climate and how to obtain them in order to provide the best possible experience in the thermal comfort of individuals. Thus, arose the studies of Fanger, which was the seed for a new era of discoveries in the area and founded the knowledge our society have today in this globally used standards and norms. Referring to these fundamental aspects of the indoor comfort, data collection was taken in situ to show in details what was happening. This study was executed in order to demonstrate the differences between the data previous and after a process of retrofitting in dwellings built in the 60s and 70s of the century past, in the district of Tjärna Ängar, Borlänge, Sweden. The comparative results using criteria such as Predicted Mean Vote (PMV), Predicted Percentage Dissatisfied (PPD), Draft Rate (DR), air velocity, Mean Radiant Temperature (MRT), Relative Humidity (RH) and air temperature, showed an improvement in 6 of the 8 parameters analyzed. Confirming the expectation that through the retrofitting the residents will be more satisfied, obtain better quality of indoor climate comfort and also increase occupied area in these dwellings.

Dans cette thèse, nous étudions des réseaux sans fil dans lesquels les terminaux mobiles sont autonomes dans le choix de leurs configurations de communication. Cette autonomie de décision peut notamment concerner le choix de la technologie d'accès au réseau, le choix du point d'accès, la modulation du signal, les bandes de fréquences occupées, la puissance du signal émis, etc. Typiquement, ces choix de configuration sont réalisés dans le but de maximiser des métriques de performances propres à chaque terminal. Sous l'hypothèse que les terminaux prennent leurs décisions de manière rationnelle afin de maximiser leurs performances, la théorie des jeux s'applique naturellement pour modéliser les interactions entre les décisions des différents terminaux. Plus précisément, l'objectif principal de cette thèse est d'étudier des stratégies d'équilibre de contrôle de puissance d'émission afin de satisfaire des considérations d'efficacité énergétique. Le cadre des jeux stochastiques est particulièrement adapté à ce problème et nous permet notamment de caractériser la région de performance atteignable pour toutes les stratégies de contrôle de puissance qui mènent à un état d'équilibre. Lorsque le nombre de terminaux en jeu est grand, nous faisons appel à la théorie des jeux à champ moyen pour simplifier l'étude du système. Cette théorie nous permet d'étudier non pas les interactions individuelles entre les terminaux, mais l'interaction de chaque terminal avec un champ moyen qui représente l'état global des autres terminaux. Des stratégies de contrôle de puissance optimales du jeu à champ moyen sont étudiées. Une autre partie de la thèse a été consacrée à des problématiques d'apprentissage de points d'équilibre dans les réseaux distribués. En particulier, après avoir caractérisé les positions d'équilibre d'un jeu de positionnement de points d'accès, nous montrons comment des dynamiques de meilleures réponses et d'apprentissage permettent de converger vers un équilibre. Enfin, pour un jeu de contrôle de puissance, la convergence des dynamiques de meilleures réponses vers des points d'équilibre a été étudiée. Il est notamment proposé un algorithme d'adaptation de puissance convergeant vers un équilibre avec une faible connaissance du réseau. / In this thesis, we study wireless networks in which mobile terminals are free to choose their communication configuration. Theses configuration choices include access wireless technology, access point association, coding-modulation scheme, occupied bandwidth, power allocation, etc. Typically, these configuration choices are made to maximize some performance metrics associated to every terminals. Under the assumption that mobile terminals take their decisions in a rational manner, game theory can be applied to model the interactions between the terminals. Precisely, the main objective of this thesis is to study energy-efficient power control policies from which no terminal has an interest to deviate. The framework of stochastic games is particularly suited to this problem and allows to characterize the achievable utility region for equilibrium power control strategies. When the number of terminals in the network is large, we invoke mean field game theory to simplify the study of the system. Indeed, in a mean field game, the interactions between a player and all the other players are not considered individually. Instead, one only studies the interactions between each player and a mean field, which is the distribution of the states of all the other players. Optimal power control strategies from the mean field formulation are studied. Another part of this thesis has been focused on learning equilibria in distributed games. In particular, we show how best response dynamics and learning algorithms can converge to an equilibrium in a base station location game. For another scenario, namely a power control problem, we study the convergence of the best response dynamics. In this case, we propose a power control behavioral rule that converges to an equilibrium with very little information about the network.

Le principal objectif de la thèse était d'établir un cadre d’étude des communications efficace énergétiquement en définissant et en justifiant de nouvelles mesures d'efficacité énergétique pour divers systèmes sans fils. En général, le rendement énergétique est défini comme le rapport entre le débit total et la puissance totale consommée par l'émetteur. Cette définition implique que, lorsqu’une re-transmission est autorisée (dans le cas d'une erreur sur les paquets), la maximisation de l'efficacité énergétique peut conduire directement à minimiser l'énergie dépensée lors de la transmission d'une unité d'information. Ce travail développe un cadre pour l'efficacité énergétique pour les cas généraux de contrôle de puissance dans la couche physique avec MIMO et inter-couche avec une arrivée de paquets sporadique. Des algorithmes centralisés et décentralisés pour atteindre un point de fonctionnement économe en énergie pour les systèmes à l'étude ont été proposés. Les résultats mettent en évidence le compromis entre la consommation d'énergie et les taux de date en ce qui concerne l'efficacité énergétique des réseaux sans fil. Le principal objectif de la thèse était d'établir un cadre d’étude des communications efficace énergétiquement en définissant et en justifiant de nouvelles mesures d'efficacité énergétique pour divers systèmes sans fil. / The main objective of the thesis was to establish a framework for energy-efficient communication by defining and justifying novel energy-efficiency metrics for various wireless systems and settings. In general, the energy-efficiency is defined as the ratio of the total data rate to the total power consumed at the transmitter. This definition implies that, when re-transmission is allowed (in the case of outage), maximizing energy-efficiency can directly lead to minimizing the energy spent in transmitting a unit of information. This work develops a framework for energy-efficiency for the general cases of power control in the physical layer with MIMO and cross-layer with a sporadic packet arrival. Both centralized and decentralized algorithms for achieving an energy-efficient working point for the systems under consideration were proposed. The results highlight the trade-off between power consumption and date rates in energy efficient wireless networks.

“Waste of resources is a mortal sin at IKEA.” – Ingvar Kamprad IKEA, as one of the biggest furniture companies in the world (Alänge, 2015), makes it interesting to have a look into their practices to gain a deeper insight by looking at how they work on a more sustainable and environmental friendlier world. Since Ingvar Kamprad, the founder of this company, mentioned sustainability from the earliest years, this work will provide an insight on how the sustainability annual reports of IKEA present their sustainability strategies to the reader every year. The researchers use the secondary analysis method to provide the theoretical framework and apply a case study to conduct the empirical data of the company IKEA. Since (Harte et al., 1991) pointed out that annual reports are an important source of environmental information. The database is in form of annual reports from the year 2010 till 2018 that were provided by the company IKEA itself. Through the pattern matching method the numbers over the years are compared and discussed due to their development. Furthermore, the areas “production” and “supplier” are selected from the supply chain management and also included in the analyzes section, since both, the development of other organizational relationships in the supply chain and the environmental corporation can become an integral part of the company (Seuring &amp; Müller, 2008). Through diagrams in the empirical chapter this work will provide a comparison between the different factors in the mentioned areas of the supply chain management and discuss the actual development and partly improvements of the factor’s “energy”, “waste”, “production” etc. and the promises and goals from the IKEA’s side.

A automação de uma central de água gelada é muito utilizada para reduzir o consumo energético de edificações comerciais ao controlar a operação dos seus componentes e consequentemente das vazões de ar e água em função da carga térmica. Considerando as estratégias de controle atualmente em uso, existe a possibilidade de melhorá-las por meio do controle das variáveis de temperatura do sistema (temperaturas de insuflação do ar, da água gelada e da água de condensação), que na maioria dos casos são mantidas fixas para as condições de dimensionamento do sistema ou alteradas apenas em função das condições externas. Estudos demonstram que o controle adequado de cada uma dessas temperaturas nas condições de operação momentâneas (condições climáticas e carga térmica), seja de forma individualizada ou integradas, pode proporcionar reduções significativas no consumo de energia do sistema de climatização. Dessa forma, o presente estudo avaliou os ganhos de uma automação isolada e integrada dessas três temperaturas em base anual para as condições climáticas brasileiras, implementando a automação em diferentes cidades representativas do zoneamento bioclimático brasileiro via simulação computacional utilizando o software EnergyPlus(TM) para uma edificação comercial típica. Os resultados obtidos para a automação integrada indicam reduções globais de consumo que variam com a condição climática entre 5,03% e 19,68% quando comparado com o controle de temperatura fixa, e quando comparado com um controle que varia apenas em função das condições externas as reduções variam entre 3,22% e 8,21%. Esses resultados demonstram que o controle sugerido é melhor que os modelos adotados como referência de mercado. / Automation of a central chilled-water plant is widely used to reduce the energy consumption of commercial buildings by controlling the operation of its components and consequently the air and water flow rates according to the thermal load. Considering the control strategies currently in use, there is a possibility to improve them by controlling the system temperature variables (air insufflation, cold and condensation water temperatures), which in most cases are fixed in system design conditions or variable only according to the external weather. Studies demonstrate that an adequate control of each of these temperatures under momentary operating conditions (climatic conditions and thermal load), whether in an individualized or integrated way, can provide significant reductions in the energy consumption of the HVAC system. Thus, the present study intends to evaluate the energy consumption gains of an individualized and integrated automation of the three variable temperatures on an annual basis for Brazilian climatic conditions, implementing automation for different cities representing the Brazilian bioclimatic zoning. Such evaluation was made by computer simulation using EnergyPlus(TM) software for a typical commercial building. The results obtained with the integrated automation show savings in global consumption that change with the weather between 5,03% and 19,68% when compared with a fixed control, and when compared with a control that varies according to weather conditions the savings are between 3,22% and 8,21%. These results show that the proposed control is better than both models adopted as market benchmarks.