Vibration energy harvesting has been widely investigated by academia and industry in the past decade with focus on developing distributed power sources. One of the prime goals of energy harvesters is to provide power to wireless sensors allowing for the placement of these sensors in the remote and inaccessible areas where battery is not an option. Electromechanical modeling approaches have been developed for enhancing the mechanical to electrical conversion efficiencies utilizing electromagnetic, piezoelectric, and magnetostrictive mechanisms. Models based upon the constitutive equations for these three conversion mechanisms, supported by extensive experimental results available in literature, suggest that power requirement through energy harvesters can be met only when the total volume is in the range of 1-100 cm3. There exists a critical volume of 0.5 cm³ at which above which the electromagnetic mechanism exhibits higher power density as compared to the other mechanisms. Therefore, in this thesis electromagnetic energy conversion was adopted to develop high power energy harvesters. We also present a novel vibration energy harvesting method which rivals the power density and bandwidth of the traditional methods. The overarching theme throughout the design process was selecting the structure and fabrication methodology that facilitates the transition of the technology. The experimental models were characterized at accelerations and frequencies typically found in the environmental vibration sources. The thesis provides in-depth the design, modeling, and characterization of a vibration energy harvester which creates relative motion differently than the conventional harvesters. Conventional designs rely on amplifying the original source displacement operating at the resonance condition. In the harvester design proposed in this thesis, the relative motion is created by cancelling the vibration at one location and transferring the source vibration directly to another location by combining a vibration isolator with a vibration absorber. In this novel configuration, termed as Direct Vibration Harvester (DVH), the energy is harvested directly from the vibrating source mass rather than a vibrating seismic mass attached to the source increasing the harvesting bandwidth and power density. Four bar magnet and magnetic levitation architectures were modified and modeled to reach closer to the theoretical maximum power densities. Extensive FEM was utilized to understand the performance limitations of the existing structures and the results from this analysis paved the pathway towards the development of the DVH. �A comparative analysis of the performance of the DVH with the traditional harvesting methods in terms of normalized power output and bandwidth was conducted. Performance improvements of DVH required development of the high efficiency rotational generators as linear to rotational conversion occurs in the DVH. The optimized rotational generator was modeled and all the predicted performance metrics were validated through experiments. The generator was applied towards the fabrication of DVH and also in a micro windmill. The power density of the micro windmill was found to be better than all the other results reported in literature. Extensive fluid and structural modeling was conducted to tailor the performance of the micro windmill in the desired wind speed range. Combined, this thesis provides significant advancement on many fronts. It pushes the magnetic levitation and four-bar mechanism harvester systems to their theoretical limits. It demonstrates a novel direct vibration harvester that has the possibility of surpassing the power density and bandwidth of all the known vibration harvester with large magnitude of output power. It provides a design process for an efficient small scale electromagnetic generator that can form for the backbone of many rotational and linear harvesters. This generator was used to develop the world's highest power density micro windmill in the small wind speed range. / Ph. D.

Cal Poly’s Recreation Center expansion project provides an opportunity to implement Energy Harvesting From Exercise Machines (EHFEM). Part of this implementation is a system that reports the exercise machines’ energy production. Although products capable of reporting exercise machine energy harvesting statistics exist, they have limited capabilities. This thesis project defends a system capable of reporting exercise machine power statistics in near real-time. The system consists of display, database, and power measurement modules. The display module presents statistics in an interactive, graphical, and widely-accessible way. The database module provides an efficient way of organizing and accessing stored statistics. Multiple power measurement module types gather power and energy generation measurements from multiple exercise machine types and transmit those measurements to the database module over the computer network.

Du, Xiaona. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2011. / Includes bibliographical references (leaves 65-74). / Abstracts in English and Chinese. / ABSTRACT --- p.i / 摘要 --- p.iii / ACKNOWLEDGEMENTS --- p.iii / TABLE OF CONTENTS --- p.iv / LIST OF FIGURES --- p.xi / LIST OF TABLES --- p.ix / Chapter CHAPTER ONE --- INTRODUCTION --- p.1 / Chapter 1.1 --- Background --- p.2 / Chapter 1.1.1 --- Development of portable devices --- p.2 / Chapter 1.1.2 --- Energy harvesting --- p.2 / Chapter 1.1.3 --- Piezoelectric energy harvesting --- p.5 / Chapter 1.1.4 --- Impact based piezoelectric energy harvester --- p.10 / Chapter 1.1.5 --- Operation of piezoelectric materials --- p.14 / Chapter 1.2 --- Research Objective --- p.16 / Chapter 1.3 --- Thesis Organization --- p.19 / Chapter CHAPTER TWO --- DESIGN AND MODELING OF AN EXTENDED ROTARY ENERGY HARVESTER --- p.20 / Chapter 2.1 --- Design Considerations of an Extended Rotary Energy Harvester --- p.20 / Chapter 2.2 --- Models of Rotary Energy Harvesters --- p.24 / Chapter 2.3 --- Simulation Results --- p.33 / Chapter 2.4 --- Chapter Summary --- p.37 / Chapter CHAPTER THREE --- "PROTOTYPE, TESTING AND OUTPUT POWER OF EXTENDED ROTARY ENERGY HARVESTER" --- p.38 / Chapter 3.1 --- Prototype and Experiment --- p.38 / Chapter 3.2 --- Output Power --- p.44 / Chapter 3.2.1 --- Maximum tip displacement on output power --- p.44 / Chapter 3.2.2 --- Rotational frequency on output power --- p.47 / Chapter 3.3 --- Chapter Summary --- p.50 / Chapter CHAPTER FOUR --- COMPARISON BETWEEN E-REH AND REH --- p.51 / Chapter 4.1 --- Force on Output Power --- p.52 / Chapter 4.2 --- Rotational Frequency on Output Power --- p.54 / Chapter 4.3 --- Comparison on Design Space --- p.59 / Chapter 4.4 --- Chapter Summary --- p.62 / Chapter CHAPTER FIVE --- CONCLUSION AND FUTURE WORK --- p.63 / Chapter 5.1 --- Conclusion --- p.63 / Chapter 5.2 --- Future Work --- p.64 / BIBLIOGRAPHY --- p.65

This work aims to demonstrate the design and simulation of a Radio Frequency (RF) energy-harvesting circuit, from receiving antenna to the point of charge collection. The circuit employs a custom-designed antenna based around Koch fractal loops, selected for their small physical size, good multiband behaviour and ease of size scalability, as well as a power-efficient seven-element Greinacher rectification section designed to charge a super-capacitor or rechargeable battery for later use. Multiple frequency bands are tapped for energy and this aspect of the implementation was one on the main focus points. The bands targeted for harvesting in this thesis will be those that are the most readily available to the general Canadian population. These include Wi-Fi hotspots (and other 2.4GHz sources), as well as cellular (850MHz band), Personal Communications Services (1900MHz band) and WiMax (2.3GHz) network transmitters.

The demand for portable permanent sources of electrical energy increases every day to power portable or non-accessible devices. Energy harvesting from vibrations offers a non-traditional source of energy. It is renewable and prevailing, since nature around is rich in kinetic energy that can be harvested. In this work, we have developed two mechanisms to harvest energy from low-frequency vibrations present in nature using electromagnetic transduction. The harvesting mechanisms use a mass-on-spring mechanical oscillator to capture kinetic energy from a host body. Prototypes embodying the two harvesting mechanisms were fabricated and tested. We identi ed the system parameters of the harvester prototypes and generated their frequency-response curves. We analyzed the results using and compared them with mathematical models of the system dynamics to characterize the harvesters' performance including their output power, center frequency, and harvesting bandwidth. We were successful in demonstrating energy harvesters that can harvest low-frequency vibration with center frequencies in the range of 8-14 Hz, harvesting bandwidth in the range of 8-12Hz, and output power on the order of 1mW. The realized harvesters are relatively small, a few inches in dimension, and light, a few tens of grams in mass. We also introduced a novel electromagnetic transduction mechanism that can be used in harvesting low-frequency vibrations.

This work aims to demonstrate the design and simulation of a Radio Frequency (RF) energy-harvesting circuit, from receiving antenna to the point of charge collection. The circuit employs a custom-designed antenna based around Koch fractal loops, selected for their small physical size, good multiband behaviour and ease of size scalability, as well as a power-efficient seven-element Greinacher rectification section designed to charge a super-capacitor or rechargeable battery for later use. Multiple frequency bands are tapped for energy and this aspect of the implementation was one on the main focus points. The bands targeted for harvesting in this thesis will be those that are the most readily available to the general Canadian population. These include Wi-Fi hotspots (and other 2.4GHz sources), as well as cellular (850MHz band), Personal Communications Services (1900MHz band) and WiMax (2.3GHz) network transmitters.

Thesis (M.S.)--Oregon State University, 2010. / Printout. Includes bibliographical references (leaves 79-82). Also available on the World Wide Web.

This work aims to demonstrate the design and simulation of a Radio Frequency (RF) energy-harvesting circuit, from receiving antenna to the point of charge collection. The circuit employs a custom-designed antenna based around Koch fractal loops, selected for their small physical size, good multiband behaviour and ease of size scalability, as well as a power-efficient seven-element Greinacher rectification section designed to charge a super-capacitor or rechargeable battery for later use. Multiple frequency bands are tapped for energy and this aspect of the implementation was one on the main focus points. The bands targeted for harvesting in this thesis will be those that are the most readily available to the general Canadian population. These include Wi-Fi hotspots (and other 2.4GHz sources), as well as cellular (850MHz band), Personal Communications Services (1900MHz band) and WiMax (2.3GHz) network transmitters.

No description available.

In this thesis, we focus on linear online power control policies for the energy harvesting communications. In the first part of the thesis, greedy policy is investigated as a special case of linear policies. The tight upper and lower bounds on the greedy threshold (c*) are provided in semi-universal settings where few parameters are known from the actual arrival distribution and clipped arrival distribution. Then the optimality region of the greedy policy is discussed. In the second part, various notions of optimal slope (s*) linear policy are discussed. The numerical results show the existence of optimal linear policy with strictly better performance than the conventional fixed fraction policy in terms of the multiplicative ratio. / Thesis / Master of Applied Science (MASc)