Recent advances in wireless communication and micro-electro-mechanical systems (MEMS) have led to the development of implementation of low-cost, low power, multifunctional sensor nodes. These sensor node are small in size and communicate untethered in short distances. The nodes in sensor networks have limited battery power and it is not feasible or possible to recharge or replace the batteries, therefore power consumption should be minimized so that overall network lifetime will be increased. In order to minimize power consumed during idle listening, some nodes, which can be considered redundant, can be put to sleep. In this thesis study, basic routing algorithms and duty cycle control algorithms for WSNs in the literature are studied. One of the duty cycle control algorithms, Role Alternating, Coverage Preserving, and Coordinated Sleep algorithm (RACP) is examined and simulated using the ns2 simulation environment. A novel duty cycle control algorithm, Sink Initiated Path Formation (SIPF) is proposed and compared to RACP in terms of sleep sensor ratio and time averaged coverage.

The shortage of clean water has become a significant global problem, and capacitive deionization (CDI) is a technology that can be used to help relieve the problem. A Ćuk converter system that can recover energy from CDI cells is described. This converter transfers energy between two CDI cells when a cell is in its desorption period, allowing energy that would otherwise be lost to be recovered and improving overall system efficiency. In order to control the states of the MOSFET switches in the converter, a self boost charge pump is used. In this way, the microcontroller can control system duty cycle and optimize energy efficiency. A design method of reducing ripple losses caused by passive elements is presented. Several sensor circuits and their design methods that can minimize power losses are shown. The influence of initial voltage drop and voltage ramp time is also examined. This Ćuk converter system is tested using a dummy cell and a real CDI cell. The converter system shows promising performance experimentally.

The cost effective comb based laser sources are considered to be one of the prominent emitters used in optical communication (OC) and photonic integrated circuits (PIC). With the rising demand for delivering triple-play services (voice, data and video) in FTTH and FTTP-based WDM-PON networks, metropolitan area network (MAN), and short-reach rack-to-rack optical computer communications, a versatile and cost effective WDM transmitter design is required, where several DFB lasers can be replaced by a cost effective broadband comb laser to support on-chip optical signaling. Therefore, high performance quantum dot (Q.Dot) comb lasers need to satisfy several challenges before real system implementations. These challenges include a high uniform broadband gain spectrum from the active layer, small relative intensity noise with lower bit error rate (BER) and better temperature stability. Thus, such short wavelength comb lasers offering higher bandwidth can be a feasible solution to address these challenges. However, they still require thorough characterization before implementation. In this project, we briefly characterized the novel quantum dot comb laser using duty cycle based electrical injection and temperature variations where we have observed the presence of reduced thermal conductivity in the active layer. This phenomenon is responsible for the degradation of device performance. Hence, different performance trends, such as broadband emission and spectrum stability were studied with pulse and continuous electrical pumping. The tested comb laser is found to be an attractive solution for several applications but requires further experiments in order to be considered for photonic intergraded circuits and to support next generation computer-communications.

This thesis describes the design and implementation of the transistor inverter to the subject of power electronics first outcome of this thesis will transistorized inverter that will serve as a demonstration tool in laboratory practice course electrical power. The laboratory preparation, students will be able to virtually test your theory acquired knowledge of the issue. Part of the theoretical analysis will be proposed circuit simulation program through classes Spice.

The notorious fuel consumption and environmental impact of conventional diesel refuse collection trucks (D-RCTs) encourage collection fleets to adopt alternative technologies with higher efficiency and lower emissions/noise impacts into their fleets. Due to the nature of refuse trucks’ duty cycles with low driving speeds, frequent braking and high idling time, a battery-electric refuse collection truck (BE-RCT) seems a promising alternative, taking advantage of energy-saving potentials along with zero tailpipe emissions. However, whether or not this newly-introduced technology can be commercially feasible for a collection fleet and/or additionally mitigate GHG emissions should be examined over its lifetime explicitly for the specific fleet. This study evaluates the performance of a D-RCT and BE-RCT in a collection fleet to assess the potential of BE-RCT in reducing diesel fuel consumption and the total GHG emissions. A refuse truck duty cycle (RTDC) was generated representing the driving nature and vocational operation of the refuse truck, including the speed, mass, and hydraulic cycles along with the extracted route grade profile. As a case study, the in-use data of a collection fleet, operating in the municipality of Saanich, British Columbia (BC), Canada, are applied to develop the representative duty cycle. Using the ADVISOR simulator, the D-RCT and BE-RCT are modeled and energy consumption of the trucks are estimated over the representative duty cycle. Fuel-based Well-to-Wheel (WTW) GHG emissions of the trucks are estimated considering the fuel (diesel/electricity) upstream and downstream GHG emissions over the 100-year horizon impact factor for greenhouse gases. The results showed that the BE-RCT reduces energy use by 77.7% and WTW GHG emissions by 98% compared to the D-RCT, taking advantage of the clean grid power in BC. Also, it was indicated that minimum battery capacity of 220 kWh is required for the BE-RCT to meet the duty cycle requirements for the examined fleet. A sensitivity analysis has been done to investigate the impact of key parameters on energy use and corresponding GHG emissions of the trucks. Further, the lifetime total cost of ownership (TCO) for both trucks was estimated to assess the financial competitiveness of the BE-RCT over the D-RCT. The TCO indicated that the BE-RCT deployment is not financially viable for the examined fleet unless there are considerable incentives towards the purchase cost of the BE-RCT and/or sufficient increase in carbon tax/diesel fuel price. From the energy useevaluation, this study estimates the required battery capacity of the BE-RCT for the studied fleet, and the TCO outputs can assist them in future planning for the adoption of battery-electric refuse trucks into their collection fleet where the cost parameters evolve. / Graduate

Understanding the pulsed discharge behavior of low-rate lithium coin cells in wireless sensing systems is critical to prolong the operating life and/or reduce the size of battery-powered WSs. This dissertation presents the battery transient analysis for a sensor duty cycle, experimental studies for sustained pulse discharge cycling, and investigation on recharge strategies for a battery/power harvesting hybrid system for WSs. The transient behavior of the lithium coin cells during pulse discharge and subsequent relaxation was investigated with single-pulse experiments and theoretical analysis. The voltage response for a pulsed discharge had two parts: a region of rapid voltage change and a region of slower change. The magnitude of the rapid voltage losses was associated with ohmic and interfacial resistances. Solid phase diffusion in the cathode was found to be the major contributor to the "slow" transient voltage change that occurred during and after a pulse. An analytical model was developed to describe the time-dependent voltage and the corresponding non-uniform concentration distribution for the thick porous electrode. A fit of the analytical model to experimental data permitted an estimate of the solid phase diffusivity. Independent fitting of the pulse data and relaxation data both yielded a diffusivity of D ~ 4×10-11 cm2/s, which agreed well with measured values reported in literature. The interactive effect of battery characteristics and WS operating conditions was investigated during sustained pulsed-discharge cycling. At low standby currents (≤50 μA), the influence of the standby current on the operating voltage and battery capacity was negligible. The pulse current had a significant impact on the lower voltage and determined the maximum capacity that could be extracted from a battery regardless of the duty cycle factor. For each pulse length studied, the battery capacity increased as the standby time increased, until a maximum capacity was reached, which could not be increased by further increase in the standby time. The minimum standby time for full (or near full) relaxation for duty cycles with different pulse length was found to correlate well with ratio ts/tp2. Battery pulse discharge-recharge cycling as would occur in a hybrid power system was investigated, and the recharge strategies were evaluated in terms of capacity loss over cycling and energy efficiency. Results from the cycling tests suggested the importance of a rest period between the discharge and charge step of a cycle. PRCR cycling with a 2 s rest period could lower the capacity loss to 25% or less of that of PC cycling with no rest period over 10,000 cycles. Cycling the battery at 80% SOC rather than at 100% SOC (3.1 V) significantly reduced the capacity loss during cycling.

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Les réseaux de capteurs sans fil qui conviennent pour vaste domaine d’applications, constituent une solution prometteuse qui répond à toute exigence de surveillance continue. L’autonomie énergétique des nœuds constitue un facteur de vulnérabilité qui influe directement leur longévité et la capacité du réseau à assurer longuement la couverture d’une zone géographique d’intérêt. La gestion de consommation énergétique représente la seule approche pour accroître la durée de vie de ces réseaux et leur conférer une autonomie raisonnable. Des solutions logicielles proposées à travers les protocoles MAC, apportent des améliorations significatives à la minimisation de la dépense énergétique des nœuds. Elles permettent de réduire les périodes d’écoute du canal qui, représente l’opération la plus coûteuse en termes d’énergie dans le fonctionnement des nœuds de capteurs sans fil. Néanmoins, se limiter à ces solutions n’est pas suffisant pour garantir une longévité acceptable. La seule méthode pour optimiser la conservation d’énergie dans les RCSFs est de mettre chaque nœud constamment en mode faible puissance et d’utiliser un mécanisme de télé-réveil à travers des signaux de réveil. Cela implique, l’utilisation de circuits de réveil de faible consommation qui assurent la surveillance de canal et qui déclenchent le réveil des nœuds uniquement à chaque fois qu’événement d’intérêt se produit. Dans ce contexte, une quantité importante de travaux ont proposés l’utilisation d’un mécanisme d’adressage (adresses MAC ou d’autres informations binaires), pour permettre aux nœuds non concernés de retourner rapidement dans son état de sommeil. Cette démarche est intéressante, mais implique toutefois une dépense énergétique non négligeable, liée à la réception et au traitement des informations d’adresse au niveau de tous les nœuds. La solution la plus efficace énergétiquement serait l’utilisation d’une autre forme d’adresse. Cette thèse s’inscrit dans le contexte de minimisation de la consommation énergétique des RCSFs par la mise en œuvre d’un adressage qui permet aux nœuds de recevoir et de traiter les signaux de réveil, sans allumer leur module de communication principal. Il s’agit pour nous de supprimer la dépense énergétique liée à l’allumage du module RF et à la réception de paquets d’adresse, en se tournant vers l’exploitation de la durée des signaux de réveils. Notre solution se repose sur les caractéristiques matérielles du microcontrôleur (IRQ, Timer/Counter) des nœuds de capteurs. Elle permet de réduire les complexités liées aux conditionnements des signaux de réveils. Notre solution est implémentée sur un réseau de petite taille. Elle est évaluée expérimentalement et ses performances énergétiques sont comparées à celles d’un schéma classique de télé-réveil sans mécanisme d’adressage et à celles d’un schéma classique basé sur le duty-cycling. / Wireless sensor networks that are suitable for a wide range of applications, represent a promising solution that meets any requirement for continuous monitoring. The energy autonomy of sensor nodes constitutes a vulnerability factor that directly affects their longevity and the capacity of the network to ensure long coverage of the geographical area of interest. Energy consumption management is the only way to increase the lifespan of these networks and to give them a reasonable autonomy. Software solutions proposed through MAC protocols, bring significant improvements to the minimization of the energy expenditure of sensor nodes. They reduce the idle-listening periods which represents the most expensive operation in terms of energy, in the operation of the wireless sensor nodes. However, Focusing lonely on these solutions is not enough to guarantee acceptable longevity. The only way to optimize energy conservation in the WSN is to constantly put each node in low power mode and use a wakeup mechanism through wake-up signals. This involves the use of low-power wake-up circuits that provide channel monitoring, and trigger node wake-up only whenever event of interest occurs. In this context, a significant amount of work has proposed the use of an addressing mechanism (MAC addresses or other binary informations), to allow non-concerned nodes to quickly return to their sleep state. This approach is interesting, but involves a significant energy expenditure, related to address information’s reception and processing at all nodes. The most energy efficient solution would be the use of another type of address. This thesis is part of the context of minimizing the energy consumption of the WSN, using an addressing system that allows sensor nodes to receive and process the wake-up signals, without turning on their main communication module. It is to eliminate the energy expenditure related to the RF module’s activation and the reception of address packets, by exploiting wakeup signals duration. Our solution is based on the hardware characteristics of the microcontroller (IRQ, Timer/Counter) of sensor nodes. It reduces the complexities related to wakeup signals conditioning. Our solution is implemented on a small network. Its evaluations were done experimentally and its energy performance is compared to a conventional wake-up mechanism without addressing,and a conventional scheme based on duty-cycling.

The work focuses on introduction to the topic of wireless sensor networks and brings readers the various aspects of problem solving in these networks. Work is closely focused on the energy performance when communicating between devices on a network and discusses the causes of excessive energy consumption. It also addresses the mechanisms for saving energy and is also engaged today protocols that its contribution to proposing solutions to problems. The author had also proposes an adapted protocol, based on lessons learned from previous theoretical sources.