Urban areas contain significant amounts of asphalt pavement. When exposed to the sun, asphalt pavement absorbs solar radiation and stores it as thermal energy raising its temperature. According to the urban heat island effect (UHIE), the pavement releases the thermal energy back to the surrounding air resulting in a rise in local air temperature. A pipe network containing a passing fluid installed in the pavement can reduce the UHIE. The fluid captures the thermal energy stored in the pavement, reducing air and pavement temperatures as well as providing heated water for other applications. The heat transfer/harvesting system can be optimized to produce the desired cooling of the pavements. This research addresses the economic feasibility of a pipe network by design as well as structural performance through computer modeling. To design the pipe network and predict its economic feasibility an Excel spreadsheet was programmed. It requires local air temperature data to determine the yearly temperature profile within the pavement and to calculate the amount of thermal energy that could be extracted. By varying design parameters such as fluid flow rate, it produces a matrix of payback periods. Structural conditions were considered for the installation of the proposed system. To simultaneously evaluate the thermal and structural performance of the pipe network installation, a finite element model was created using COMSOL Multiphysics©. A typical value of solar radiation and a standard truck tire wheel load were applied to the model to simulate the intended application of the pipe network. The result of this thesis is a method and a tool to design and analyze with respect to economic and structural performance a pipe network used to extract the thermal energy stored in asphalt pavements and reduce the UHIE.

We develop a simplified one-dimensional numerical model that simulates the performance of thermoelectric generators (TEG). The model is based on the energy and electrical potential field equations. The Seebeck coefficient, thermal conductivity, electrical resistivity and Thomson coefficient of the TEG material are used to predict the harvested power. Bismuth-telluride is used as semiconductors materials of the TEG, which is the most commonly used material by industry. Experiments on three TEG modules were performed to validate the numerical model. A comparison with predicted levels of harvested energy based on the TEG specifications is also performed. The results show differences between the experimental and numerical values on one hand and the predicted ones on the other hand. The reason for these differences are discussed. A procedure to estimate the sensitivity of the harvested power to different inputs and TEG parameters is detailed. In the second part of the dissertation, we integrate a thermoelectric generator with an organic storage device. The performance of the integrated system for different values of load resistances and temperature gradients is determined. Finally, we demonstrate that power generated from a TEG is related to the flow rate in a pipe and can, thus, be used as a flow meter. Particularly, a dimensionless relation between the TEG's peak power and Reynolds number is determined. / Ph. D.

La récupération d’énergie est un thème de recherche prometteur qui explore un large éventail de sources. Parmi ces sources, on trouve l’énergie mécanique, thermique, électromagnétique, etc. Cette thèse se propose d’explorer des solutions techniques de récupération de l’énergie électromagnétique ambiante. Ce type d’énergie offre une belle opportunité pour participer à l’alimentation, partielle ou complète, d’un système de communication sans fil à basse consommation. Beaucoup d’applications intéressantes telles que les réseaux de capteurs sans fil (WSN), assurant ainsi l’IoT (internet of things), dans le domaine médical et dans la sécurité, sont dotés d’une antenne. Or cette antenne qui est un composant passif volumineux n’est utilisée qu’une faible fraction du temps pour les seules communications. Dans le cadre de la récupération d’énergie RF, l’idée est de mettre à profit ce composant pour glaner l’énergie électromagnétique ambiante, malgré la faible puissance récupérée. Associée à l’antenne, la récupération d’énergie RF est basée sur la mise en œuvre de diodes en redresseurs. Dans ce manuscrit, des diodes intégrées issues d’une technologie moderne : FDSOI 28 nm sont utilisées.A l’issue de ces travaux, trois « runs » dont deux en technologie FDSOI ont pu être réalisés. Des convertisseurs d’énergie RF, du type Dickson, d’un et deux étages, ont été conçus et réalisés à l’aide de cette technologie, mesurés et même comparés à des convertisseurs RF-DC réalisés avec une autre technologie BiCMOS 55 nm. Les convertisseurs réalisés sont à l’état de l’art au niveau du rendement de conversion énergétique pour une puissance donnée de l’ordre de -20 dBm. La technologie FD-SOI offre un nouveau degré de liberté à l’aide de la polarisation de la grille arrière (BG : Back Gate). Cette polarisation du BG permet de modifier les paramètres de l’élément non-linéaire à la base de la conversion. Par ailleurs, une étude sur la réalisation d’une diode Schottky intégrée dans le processus de la FDSOI 28 nm a même été envisagée. A l’issue de ces premières expériences, une méthode d’optimisation de la conception de ces convertisseurs Dickson à partir d’un cahier des charges simplifiée, a été proposée. / Energy harvesting is a promising research theme which analyzes a wide range of sources for the application. These sources can be mechanical, thermal or electromagnetic, etc. Hereby, the work presented explores technical solutions for ambient electromagnetic energy harvesting. Electromagnetic energy is capable of partly or completely supplying energy to low-power wireless communication systems. Many interesting applications are feasible, such as, wireless sensor networks (WSN) ensuring IoT (Internet-of-Things), in the medical field, security, by using equipments containing an antenna. However, the antenna is a voluminous passive component which is utilized merely for a fraction of the time, i.e., just for communications. The underlying idea of RF energy harvesting is to use the antenna to harvest the ambient electromagnetic energy, despite the low power recovered. Associated with the antenna, the RF energy harvesting is based on implementing diodes in rectifiers. In this manuscript, integrated diodes from modern technology: FD-SOI 28 nm are studied.In this work, three run for RF energy harvesting are designed. Two of them are realized in FD-SOI technology. One and two stage Dickson rectifiers for RF energy harvesting using FD-SOI are designed, characterized, measured and compared to RF-DC converters made with 55nm BiCMOS technology. These rectifiers are state-of-the-art in terms of the power conversion efficiency for a given power of the order of -20 dBm. Furthermore, FD-SOI technology offers a new degree of freedom with the back gate polarization (BG). This polarization of the BG makes it viable to change the parameters of the non-linear elements at the base of the conversion. Moreover, an investigation of integrated Schottky diodes using FDSOI 28 nm is presented. At the end of these experiments, a method of optimizing of the design of these Dickson converters based on simplified specifications is proposed.

An antenna for light harvesting is an organized multicomponent system in which several chromophoric molecular species absorb the incident light and channel the excitation energy to a common acceptor component. In this study, Click chemistry has been successfully applied in the synthesis of a bay region tetraboron dipyrrin (BODIPY) appended perylenediimide (PDI). This light-harvesting molecule presents a large cross section for the absorption of light in the visible region. Excitation energy is efficiently channeled to the perylenediimide core. This novel antenna system is the first demonstration of the efficiency of energy transfer in a BODIPY- PDI bichromophoric system and appears to be highly promising for the design and synthesis of similar dendritic structures.

Progress in energy harvesting technology and the increasing need for the energy efficient and environmentally friendly applications have called for reconsideration of communication systems. This reconsideration results in new problem formulations regarding the recent developments on energy harvesting systems. Recently, optimal strategies for various types of energy harvesting networks have been developed based on different harvesting models. This thesis reports the results of our research to develop the optimal scheduling structures on an energy harvesting broadcast and fading channels, and to devise online implementable algorithms for a point-to-point communication system. Particularly, structural properties of an optimal offline schedule in, (1) an energy harvesting broadcast channel with one transmitter two receivers, (2) a single user communication system under fading conditions, are investigated. Moreover, an online algorithm is proposed for a single-user energy harvesting communication system considering the physical constraints and necessities regarding implementation. The proposed scheme is implemented through GNU Radio framework on a USRP device.

Vibration converters based on piezoelectric materials are currently becoming increasingly important for powering low-power wireless sensor nodes and wearable electronic devices. Piezoelectric materials generate variable electrical charges under mechanical stress, requiring an energy management interface to meet load requirements. Resonant interfaces like Parallel Synchronized Switch Harvesting on Inductor (P-SSHI) are highly efficient and robust to energy sources and loads variations. Nevertheless, SSHI circuits require synchronous switch control for efficient energy transfer. At irregular excitation, SSHI circuits may not perform optimally because the resonant frequency of the circuit is typically tuned to match the frequency of the energy source, which in the case of footsteps can be irregular and unpredictable. In addition, the circuit may also be susceptible to noise and interference from irregular excitations, which can further affect its performance. The aim is to design a self-powered energy management solution that can operate autonomously even at low frequencies and for irregular chock excitations, while at the same time allowing higher energy flow to the energy storage device and maintaining high levels of energy efficiency. To evaluate the performance of the proposed circuit, a piezoelectric shoe insole is designed and used for testing with different storage capacitance values and loads as a proof of the circuit’s adaptability to various loading conditions.:1 Introduction 2 Theoretical background 3 State of the art of piezoelectric energy harvesting interfaces 4 Novel approach of SP-PSSHI piezoelectric energy harvesting interface 5 Experimental investigations 6 Conclusions and Outlook

The proliferation of embedded systems, mobile devices, wireless sensor applications and in- creasing global demand for energy directed research attention toward self-sustainable and environmentally friendly systems. In the field of communications, this new trend pointed out the need for study of energy constrained communication and networking. Particularly, in the literature, energy efficient transmission schemes have been well studied for various cases. However, fundamental results have been obtained mostly for offline problems which are not applicable to practical implementations. In contrast, this thesis focuses on online counterparts of offline transmission scheduling problems and provides a theoretical background for energy efficient online transmission schemes. The proposed heuristics, Expected Threshold and Expected Water Level policies, promise an adequate solution which can adapt to short-time-scale dynamics while being computationally efficient.

Almost all life on Earth depends on the products of photosynthesis - the biochemical process whereby solar energy is stored as chemical-rich compounds. The energy of captured photons is transferred through a network of pigment-protein complexes towards the reaction center. The reaction center is responsible for trans-membrane charge separation, which generates a proton motive force which drives all subsequent biochemical reactions. The ultrafast (femtosecond) nature of the primary processes in photosynthesis is the main reason for its astonishing efficiency. On this timescale, quantum effects start to play a role and can appear in measured spectra as oscillations. It has been hypothesized that these are evidence of wave-like energy transfer. To unveil the fundamental principals of ultrafast excitation energy transfer in both natural and artificial light-harvesting systems, advanced spectroscopy techniques have been utilized. Coherent two- dimensional electronic spectroscopy is a state of the art technique which allows the most complete spectroscopic and temporal information to be extracted from the system under study. This technique has allowed us to identify a new photophysical process where the coherence of the initially excited state is shifted to the ground state upon an energy transfer step. Coherence...

Significant advances in wind turbine technology have increased the need for maintenance through condition monitoring. Indeed condition monitoring techniques exist and are deployed on wind turbines across Europe and America but are limited in scope. The sensors and monitoring devices used can be very expensive to deploy, further increasing costs within the wind industry. The work outlined in this thesis primarily investigates potential low-cost alternatives in the laboratory environment using vibration-based and modal testing techniques that could be used to monitor the condition of wind turbine blades. The main contributions of this thesis are: (1) the review of vibration-based condition monitoring for changing natural frequency identification; (2) the application of low-cost piezoelectric sounders with proof mass for sensing and measuring vibrations which provide information on structural health; (3) the application of low-cost miniature Micro-Electro-Mechanical Systems (MEMS) accelerometers for detecting and measuring defects in micro wind turbine blades in laboratory experiments; (4) development of an in-service calibration technique for arbitrarily positioned MEMS accelerometers on a medium-sized wind turbine blade. This allowed for easier aligning of coordinate systems and setting the accelerometer calibration values using samples taken over a period of time; (5) laboratory validation of low-cost modal analysis techniques on a medium-sized wind turbine blade; (6) mimicked ice-loading and laboratory measurement of vibration characteristics using MEMS accelerometers on a real wind turbine blade and (7) conceptualisation and systems design of a novel embedded monitoring system that can be installed at manufacture, is self-powered, has signal processing capability and can operate remotely. By applying the conclusions of this work, which demonstrates that low-cost consumer electronics specifically MEMS accelerometers can measure the vibration characteristics of wind turbine blades, the implementation and deployment of these devices can contribute towards reducing the rising costs of condition monitoring within the wind industry.

Die wechselhafte Energiebereitstellung für drahtlose Sensorknoten durch Solarzellen stellt das Energiemanagement dieser Systeme vor große Herausforderungen. Bedingt durch saisonale und kurzfristige Effekte treten kontinuierlich Schwankungen in der Eingangsleistung auf, gleichzeitig soll jedoch eine zuverlässige und konstante Systemfunktion realisiert werden. Um dies miteinander zu vereinbaren, wird ein Modell zur Beschreibung der erwarteten Eingangsleistung aufgestellt, mit welchem der planmäßige Energieverlauf bestimmt werden kann. Dieser kann wiederum mit der realen Eingangsleistung verglichen werden, um den tatsächlichen energetischen Zustand des Sensorknotens zu bestimmen. Daraus lassen sich beispielsweise Entscheidungskriterien für die Steuerung der Energieverteilung oder Betriebszustände ableiten. Im Rahmen der Arbeit werden die physikalischen Hintergründe zur Modellierung der eingehenden Sonnenenergie beschrieben, der Stand der Technik zur Modellierung aufgezeigt und ein Modell als Basis für die weiteren Untersuchungen ausgewählt. Dieses wird auf die stark limitierte Hardware von drahtlosen Sensorknoten angepasst. Die Herausforderungen liegen dabei hauptsächlich in der geringen verfügbaren Rechenleistung, wenig Datenspeicher im System und dem Ziel, möglichst wenig Energie für die Berechnung zu verbrauchen. Im Ergebnis zeigt sich, dass ein angepasstes Modell auf drahtlosen Sensorsystemen umgesetzt werden kann und trotz der starken Limitierungen lauffähig ist. Es wird eine deutliche Verbesserung in der Verteilung der Energie über den Tag ermöglicht, wodurch sich trotz wechselhafter Quelle eine konstante Systemfunktion ergibt. Nebenher wird die Zuverlässigkeit und Ausfallsicherheit erhöht und Überdimensionierungen in Energiespeicher und Solarzelle können verringert werden. Das modellbasierte Energiemanagement stellt somit einen wichtigen Baustein für eine gesicherte Energieversorgung drahtloser Sensorsysteme dar. / The volatile energy supply by solar cells for wireless sensor nodes causes vast challenges for the energy management of such systems. Conditioned by seasonal and short time effects, the incoming power continuously varies. Simultaneously a reliable and constant function of the system has to be realized. To reconcile this, a model for the expected incoming solar power has been derived, which enables the estimation of the planned energy curve. This curve can be compared with the real progression of incoming power measured in parallel, to determine the current state of energy of a sensor node. This comparison is used to derive decision criteria for the control of the energy distribution or operating conditions. Within this work, the physical backgrounds for the modelling of the incoming solar energy and the state of the art of modelling solar power are described. A model is chosen as basis for further investigations and adapted to the limited hardware of wireless sensor nodes. The main challenges are the reduced processing power, few data memory in the system and the objective to consume as few energy as possible for the calculation. The results show that an adapted model can be implemented on wireless sensor systems and that it is executable despite the heavy limitations. This enables a distinct improvement of the distribution of energy across the day, which results in a constant systems function, despite the varying incoming power. At the same time the reliability and failure safety are being improved and the oversizing of the solar cell and the storage elements can be reduced. Therefore the model based energy management is an important component for a stable power supply of wireless sensor systems.