Simultaneous Data Communication and Power Transfer Technique with Multiport Interferometric Receiver

RÉSUMÉ Le problème de la communication est généralement présenté comme un problème de trans-mission d’un message généré d’un point a un autre. Certains systèmes de communication modernes sou˙rent de contraintes énergétiques sévères. Avec le développement rapide des systèmes électroniques sans fil de faible puissance, d’innombrables activités de recherche ont été menées en vue d’explorer la faisabilité d’une alimentation à distance ou sans fil de ces systèmes. Par conséquent, la transmission d’énergie sans fil (WPT) est en cours de développe-ment en tant que technique prometteuse pour alimenter des appareils électroniques à distance et pour prolonger la durée de vie des réseaux sans fil à contrainte d’énergie. Parmi les éner-gies renouvelables récoltées dans l’environnement, les signaux RF rayonnés par les émetteurs peuvent être une ressource viable pour le transfert d’énergie sans fil, tandis que les signaux RF ont été largement utilisés comme véhicule pour la transmission d’informations sans fil (WIT). Par conséquent, le transfert simultané d’informations et la plateforme de transfert de puissance sans fil (SWIPT) deviennent bénéfiques, car il réalise les deux utilisations utiles des signaux RF en même temps et il o˙re ainsi potentiellement une grande commodité aux utilisateurs mobiles. L’antenne redresseuse, qui combine des fonctionnalités du redresseur et de l’antenne, est un élément clé pour la transmission et la récolte d’énergie sans fil. L’eÿcacité de conversion du circuit de redressement détermine les performances globales de l’antenne redresseuse. Par conséquent, pour concevoir une antenne redresseuse à haute eÿcacité qui peut garantir la qualité d’un système WPT, il convient de se concentrer davantage sur l’investigation, l’analyse et le développement de redresseurs axés sur les performances en référence à une eÿcacité de conversion radio fréquence à courant continu. D’un autre côté, les circuits redresseurs peuvent simplement récupérer l’énergie et ils ne peuvent pas décoder le signal transmis pour fins de communication. Cependant, la transmission de données est une exigence essentielle des systèmes de communication sans fil. Par conséquent, si la capacité de détection et de traitement du signal peut être ajoutée à une architecture antenne redresseuse, un récepteur avec transmission de puissance sans fil et communication de données simultanées peut être réalisé. Ce mémoire vise à étudier et à démontrer un récepteur de multifonction et de multiport qui a la capacité de collecter simultanément l’énergie sans fil et les données de communication fonctionnant à la fréquence des microondes.----------ABSTRACT The problem of communication is usually cast as one of transmitting a message generated at one point to another point. Some modern communication systems are known to suffer from severe energy constraints and power consumptions. With the rapid development of low power wireless electronic systems, countless research activities have been carried out to explore the feasibility of a remote or wireless powering of those systems. Therefore, wireless power transmission (WPT) is being developed as a promising technique, for powering electronic devices over distance and for prolonging the lifetime of energy constrained wireless networks. Among the renewable energy harvested from the environment, the RF signals radiated by transmitters can be a viable resource for wireless power transfer, while RF signals have been widely used as a vehicle for wireless information transmission (WIT). Therefore, simultaneous wireless information and power transfer (SWIPT) platform becomes appealing since it realizes both useful utilizations of RF signals at the same time, and thus potentially offers great convenience to mobile users. The rectenna, combining the functionalities of rectifier and antenna, is a key element for wireless power transmission and harvesting. The conversion efficiency of the rectifying circuit determines the overall performance of the rectenna. Therefore, to design a high-efficiency rectenna that can guarantee the quality of a WPT system, more focus should be concentrated on the investigation, analysis and development performance-driven rectifiers with reference to high RF-to-DC conversion efficiency. On the other hand, rectenna circuits can just scavenge energy and they cannot decode the transmitted signal for communication purpose. How-ever, the data transmission is an essential requirement of wireless communication systems. Therefore, if the ability of signal detection and processing can be added to a rectenna architecture then a multi-function receiver with simultaneous wireless power transmission and data communication can be realized.This dissertation aims to investigate and demonstrate a multi-function and multi-port receiver with the capability of simultaneous wireless energy harvesting and data communication operating at microwave frequency. To achieve these goals, it becomes interesting when a single receiver chain is able to convert the RF power to DC power, while at the same time converting the RF modulated signal to BaseBand (BB) signal. Therefore, the fundamental methodology to receive and convert the RF signal to BB while simultaneously harvesting power is derived and analyzed in this work

Research on a safety evaluation system for railway-tunnel structures by fuzzy comprehensive evaluation theory

Long-term health detection of railway-tunnel is the development direction and trend of future railway tunnel research. Based on the actual engineering of a railway tunnel, this study developed a safety evaluation model for railway tunnel structures using a fuzzy comprehensive evaluation method and examined a health state evaluation method suitable for most railway tunnel structures. The results showed that the evaluation method comprehensively reflected the impact of various factors, which had strong practicality. The evaluation results were clear, accurate, and consistent with engineering practice. When using the safety factor index to study the stress of a railway tunnel structure, Midas/civil analysis showed that different levels of the surrounding rock structural vault in railway tunnels were in a tensile, control-bearing capacity state. When calculating safety factors, the range of a 60° central angle of a railway tunnel vault was calculated according to the tensile control-bearing capacity. Theoretical formulas of the range of the center angle φ0 of the vault tension zone were derived and then verified by experiments and numerical analysis

Capacitor-Loaded Spoof Surface Plasmon for Flexible Dispersion Control and High-Selectivity Filtering

This letter proposes a new spoof surface plasmon transmission line (SSP-TL) using capacitor loading technique. This new SSP-TL features flexible and reconfigurable dispersion control and highly selective filtering performance without resorting to configuration change. Moreover, it requires much smaller linewidth than the conventional SSP-TL for achieving an extremely slow wave (or a highly confined field), which is quite useful for a compact system. To illustrate the design principle, several examples are designed within the frequency range of 2-8 GHz. Both numerical and experimental results are given in comparison with the conventional SSP-TL. It is demonstrated that the proposed technique provides a better performance in size reduction and dispersion reconfigurability

Bearing capacity and seismic performance of Y-shaped reinforced concrete bridge piers in a freeze-thaw environment

A quantitative study is performed to determine the performance degradation of Y-shaped reinforced concrete bridge piers owing to long-term freeze-thaw damage. The piers are discretized into spatial solid elements using the ANSYS Workbench finite element analysis software, and a spatial model is established. The analysis addresses the mechanical performance of the piers under monotonic loading, and their seismic performance under low-cycle repeated loading. The influence of the number of freeze-thaw cycles, axial compression ratio, and loading direction on the pier bearing capacity index and seismic performance index is investigated. The results show that freeze-thaw damage has an adverse effect on the ultimate bearing capacity and seismic performance of Y-shaped bridge piers in the transverse and longitudinal directions. The pier peak load and displacement ductility coefficient decrease with increasing number of freeze-thaw cycles. The axial compression ratio is an important factor that affects the pier ultimate bearing capacity and seismic performance. Upon increasing the axial compression ratio, the pier peak load increases and the displacement ductility coefficient decreases, the effects of which are more significant in the longitudinal direction

DOA Estimation for Mixed Uncorrelated and Coherent Sources in Multipath Environment

A novel direction-of-arrival (DOA) estimation method is proposed to cope with the scenario where a number of uncorrelated and coherent narrowband sources simultaneously impinge on the far-field of a uniform linear array (ULA). In the proposed method, the DOAs of uncorrelated sources are firstly estimated by utilizing the property of the moduli of eigenvalues of the DOA matrix. Afterwards, the contributions of uncorrelated sources and the interference of noise are eliminated completely by exploiting the improved spatial differencing technique and only the coherent components remain in the spatial differencing matrix. Finally, the remaining coherent sources can be resolved by performing the improved spatial smoothing scheme on the spatial differencing matrix. The presented method can resolve more number of sources than that of the array elements and distinguish the uncorrelated and coherent sources that come from the same direction as well as improving the estimation performance. Simulation results demonstrate the effectiveness and efficiency of the proposed method