Wong Kwok Ming. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2001. / Includes bibliographical references (leaves 88-93). / Abstracts in English and Chinese. / LIST OF FIGURES --- p.VI / LIST OF TABLES --- p.IX / ACKNOWLEDGEMENTS --- p.X / Chapter CHAPTER 1 --- INTRODUCTION --- p.1 / Chapter 1.1 --- Background --- p.1 / Chapter 1.2 --- Literature review on self-sensing purely active system --- p.3 / Chapter 1.3 --- Literature review on active constrained layer treatment --- p.5 / Chapter 1.4 --- Introduction to enhanced active constrained layer treatment --- p.8 / Chapter 1.5 --- Objectives of this research --- p.10 / Chapter 1.6 --- Thesis outline --- p.11 / Chapter CHAPTER 2 --- CONTROL LAW IMPLEMENTATION --- p.12 / Chapter 2.1 --- Electrical equivalent model of piezoelectric material --- p.12 / Chapter 2.2 --- Bridge circuit --- p.14 / Chapter 2.2.1 --- Strain rate sensing bridge circuit --- p.14 / Chapter 2.2.2 --- Strain sensing bridge circuit --- p.17 / Chapter 2.3 --- Control laws implementation --- p.19 / Chapter 2.3.1 --- Strain rate feedback control --- p.19 / Chapter 2.3.2 --- Positive position feedback (PPF) control --- p.21 / Chapter 2.3.3 --- Modified strain rate feedback control --- p.25 / Chapter CHAPTER 3 --- EXPERIMENTAL STUDIES --- p.28 / Chapter 3.1 --- Experimental setup --- p.28 / Chapter 3.2 --- Test of actuating ability --- p.30 / Chapter 3.3 --- Test of sensing ability --- p.32 / Chapter 3.4 --- Open loop response --- p.34 / Chapter 3.5 --- Closed loop response --- p.36 / Chapter 3.6 --- Chapter summary --- p.52 / Chapter CHAPTER 4 --- SYSTEM MODELING AND SIMULATION --- p.53 / Chapter 4.1 --- Literature review on finite element method --- p.53 / Chapter 4.1.1 --- Element stiffness matrix through potential energy --- p.57 / Chapter 4.1.2 --- Element mass matrix through kinetic energy --- p.58 / Chapter 4.2 --- System modeling --- p.59 / Chapter 4.2.1 --- Stiffness and mass matrices of beam layer --- p.63 / Chapter 4.2.2 --- Stiffness and mass matrices of piezoelectric layer --- p.64 / Chapter 4.2.3 --- Stiffness and mass matrices of VEM layer --- p.67 / Chapter 4.2.4 --- Stiffness and mass matrices of beam edge elements --- p.71 / Chapter 4.3 --- Simulation --- p.76 / Chapter 4.4 --- Chapter summary --- p.83 / Chapter CHAPTER 5 --- SUMMARY AND FUTURE WORK --- p.84 / Chapter 5.1 --- Summary --- p.84 / Chapter 5.2 --- Future Work --- p.87 / BIBLIOGRAPHY --- p.88

Law Wai Wing. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2002. / Includes bibliographical references (leaves 64-66). / Abstracts in English and Chinese. / 摘要 --- p.i / ABSTRACT --- p.ii / ACKNOWLEDGEMENTS --- p.iii / CONTENTS --- p.iv / LIST OF FIGURES --- p.vi / LIST OF TABLES --- p.ix / Chapter 1 --- INTRODUCTION / Chapter 1.1 --- Background --- p.1 / Chapter 1.1.1 --- Piezoelectric Materials --- p.1 / Chapter 1.1.2 --- Self-sensing Actuation --- p.2 / Chapter 1.2 --- Literature Review --- p.3 / Chapter 1.3 --- Motivation --- p.5 / Chapter 1.4 --- Thesis Organization --- p.6 / Chapter 2 --- STRUCTURE MODELING AND FORMULATION / Chapter 2.1 --- Overview of Piezoelectricity --- p.7 / Chapter 2.2 --- Modeling of the Smart Structure --- p.8 / Chapter 2.2.1 --- Electromechanical Conversion --- p.8 / Chapter 2.2.2 --- Model Derivation Using Hamilton's Principle --- p.10 / Chapter 2.3 --- Discretization of Equation of Motion --- p.15 / Chapter 2.4 --- Sensing Model of the Piezoelectric Sensor --- p.20 / Chapter 2.4.1 --- Strain Sensing Model --- p.21 / Chapter 2.4.2 --- Strain Rate Sensing Model --- p.23 / Chapter 2.5 --- Model Validation --- p.25 / Chapter 3 --- CONTROL OF SMART STRUCTURE / Chapter 3.1 --- Strain Rate Feedback Control --- p.27 / Chapter 3.2 --- Positive Position Feedback Control --- p.31 / Chapter 3.3 --- Unbalanced Bridge Effect on Closed Loop Stability --- p.36 / Chapter 3.4 --- Self-Compensation of Capacitance Variation --- p.39 / Chapter 4 --- EXPERIMENTAL STUDIES / Chapter 4.1 --- Experiment Setup --- p.47 / Chapter 4.2 --- Experiment Results --- p.48 / Chapter 4.2.1 --- Open Loop Response --- p.48 / Chapter 4.2.2 --- Closed Loop Response with Balanced Bridge --- p.49 / Chapter 4.2.3 --- Closed Loop Response with Unbalanced Bridge --- p.51 / Chapter 4.2.4 --- Closed Loop Response upon Sudden Change in Bridge Parameter --- p.53 / Chapter 4.2.5 --- Closed Loop Response upon Temperature Variation --- p.57 / Chapter 4.2.6 --- Frequency Response --- p.58 / Chapter 5 --- SUMMARY / Chapter 5.1 --- Conclusion --- p.51 / Chapter 5.2 --- Future Work --- p.62 / BIBLIOGRAPHY --- p.63

Ng Tsz Ho. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2004. / Includes bibliographical references (leaves 67-70). / Abstracts in English and Chinese. / ABSTRACT --- p.i / 摘要 --- p.ii / ACKNOWLEDGEMENTS --- p.iii / LIST OF FIGURES --- p.iv / LIST OF TABLES --- p.ix / Chapter CHAPTER 1 --- INTRODUCTION --- p.1 / Chapter 1.1 --- Background --- p.1 / Chapter 1.2 --- Literature Review --- p.3 / Chapter 1.3 --- Research Objectives --- p.5 / Chapter 1.4 --- Thesis Organization --- p.5 / Chapter CHAPTER 2 --- MODELING OF PIEZOELECTRIC SENSOR/GENERATOR --- p.6 / Chapter 2.1 --- Constitutive Equations --- p.6 / Chapter 2.2 --- Voltage Output of Piezoelectric Materials --- p.9 / Chapter 2.2.1 --- Short Circuit --- p.9 / Chapter 2.2.2 --- Open Circuit --- p.11 / Chapter 2.3 --- Sensitivity and Power Generation --- p.13 / Chapter 2.4 --- Modeling and Analysis of Sensor Structure --- p.23 / Chapter 2.4.1 --- Damping Ratio Estimation --- p.25 / Chapter (a) --- Half-power bandwidth method --- p.25 / Chapter (b) --- Linear interpolation method --- p.25 / Chapter 2.4.2 --- Trade-off between Resonant Frequency and Output Sensitivity of a Sensor --- p.29 / Chapter (a) --- Maximize Sme with constant wn --- p.31 / Chapter (b) --- Maximize wn with constant Sme --- p.33 / Chapter 2.5 --- Model Accuracy --- p.39 / Chapter CHAPTER 3 --- POWER HARVESTING --- p.41 / Chapter 3.1 --- Circuit Model --- p.41 / Chapter 3.2 --- Energy Storage --- p.47 / Chapter 3.3 --- Size Effect on Power Output --- p.49 / Chapter 3.4 --- Power Harvesting Circuit --- p.50 / Chapter 3.4.1 --- Performance of the Power Harvesting Circuit --- p.51 / Chapter (a) --- Power Harvesting Circuit Efficiency --- p.52 / Chapter (b) --- Useful Power Output --- p.53 / Chapter (c) --- System Efficiency --- p.56 / Chapter (d) --- Relationship between Input Excitation and Charge Time --- p.57 / Chapter 3.5 --- Harvested Energy for Wireless Transmission --- p.60 / Chapter CHAPTER 4 --- CONCLUDING REMARKS --- p.64 / Chapter 4.1 --- Sensor/Generator Design --- p.64 / Chapter 4.2 --- Potential Applications --- p.64 / Chapter 4.3 --- Conclusion --- p.65 / Chapter 4.4 --- Future Work --- p.66 / REFERENCES --- p.67 / APPENDIX --- p.71

Besides system level analyses, some implementation issues on switching interface circuits are also investigated. These interfaces show a great potential on harvesting efficiency improvement. Based on the experimental observation, it is found that there is a voltage reversion after every inversion in SSHI, which weakens the harvesting performance. This influence is caused by the dielectric loss in piezoelectric material. A revised model as well as detailed analysis are proposed to evaluate the influence of dielectric loss over the harvesting power degradation. / Considering the practical implementation, a modified self-powered switching interface circuit is proposed. It can achieve better isolation among components and involve less dissipative components. Improved analysis on this self-powered switching interface circuit is also provided. It is shown that the higher the excitation level, the more beneficial for replacing the SEH interface with the self-powered switching interface; meanwhile, the closer between the performances of self-powered and ideal (external powered) switching interfaces. / Owing to the great reduction on power consumption of integrated circuits (ICs) and miniaturization during the past decades, the energy harvesting technique has gained much interest recently with the inspiration that more devices in wireless sensor networks as well as mobile electronics could power themselves by scavenging the ambient energy in different forms. Piezoelectric energy harvesting (PEH) is one of the most widely studied techniques to scavenge energy from ambient vibration sources. With the electromechanical nature, a PEH device can be divided into mechanical and electrical parts. The two parts are linked by the piezoelectric transducer. Literatures on PEH are reviewed and discussed. In the research of PEH, generally there are four different research foci on: mechanical part, electrical part, piezoelectric transduction, and system. / This thesis provides new insight into the research of piezoelectric energy harvesting from some systematic viewpoints. The modeling process of a single degree-of-freedom (SDOF) PEH system is firstly discussed. It shows how the model of a PEH device is built from the material level to element level, and then to device level. In the systematic analysis to PEH devices, the energy flow and impedance based analysis are highlighted. A detailed analysis on the energy flow within the PEH system provides good understanding on the system. However, up to now, most of the researches on PEH have been mainly concerned with the absolute amount of energy that can be harvested from vibrating structures; the detailed energy flow within the system as well as its effect on the vibrating structure, were seldom discussed. By studying the energy flow within three applications of standard energy harvesting (SEH), resistive shunt damping (RSD), and synchronized switching harvesting on inductor (SSHI), it can be concluded that, in a PEH system, the two functions of energy harvesting and dissipation are coexistent. Both of them bring out structural damping. New factors are defined to give a more comprehensive evaluation on the energy flow in PEH systems. / To enhance the harvesting power by using the impedance matching is not new; yet, previous literatures on impedance matching for PEH oversimplified the problem. Without clarification on the energy flow in the PEH system, their objectives on power optimization were ambiguous. Some literatures even assumed that the harvesting interfaces, which are nonlinear in nature, can be equalized to linear loads, and the load impedance can be arbitrarily set. With the understanding on energy flow within piezoelectric devices, we clarify the objective of impedance matching, and further demonstrate that the range of equivalent impedance of existing harvesting interfaces is in fact constrained, rather than unlimited. The analyses on system level provide guideline to improve the harvesting performances. Improvements can be made with innovative designs in either mechanical configuration, piezoelectric transducer, or interface circuit. / Liang, Junrui. / Adviser: Wei-Hsin Liao. / Source: Dissertation Abstracts International, Volume: 73-03, Section: B, page: . / Thesis (Ph.D.)--Chinese University of Hong Kong, 2010. / Includes bibliographical references (leaves [145]-155). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [201-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstract also in Chinese.

Based on constitutive equations of piezoelectricity and two-port modeling method, the models of piezoelectric materials are investigated. The equivalent circuit models of the piezoelectric element in the energy harvesting system are explored. It is found that there exists an optimal external impedance that gives the maximum output power. Experiments are conducted to verify the optimal impedance theory. / The energy storage devices in the piezoelectric energy harvesting system are analyzed. The charge/discharge efficiencies of the energy storage devices are mainly considered. Based on the analysis of the electric characteristics of the energy storage devices, we find the leakage resistances of the energy storage devices are the dominant factor that influences the charge/discharge efficiency in the piezoelectric energy harvesting system. A quick test method is proposed to experimentally study the charge/discharge efficiencies of the energy storage devices. The experimental results verify our findings. Adaptability, lifetime, and protection circuit of the energy storage devices are also discussed. It can be concluded that the supercapacitors are suitable and more attractive than the rechargeable batteries to store the energy in the piezoelectric energy harvesting system. / Two schemes of piezoelectric energy harvesting circuits are analyzed: one-stage and two-stage energy harvesting schemes. The efficiency of the two-stage harvesting scheme is found to be related to several factors including the energy storage device voltage. Analysis and experiments using one-stage energy harvesting circuit to harvest a varying excitation source are explored. The results show that one-stage energy harvesting scheme can achieve higher efficiency than the two-stage scheme towards a range of energy storage voltages. / Using piezoelectric elements to harvest energy from ambient vibration has been of great interest recently. Because the power harvested from the piezoelectric elements is relatively low, energy storage devices are needed to accumulate the energy for intermittent use and energy harvesting circuits are applied to transfer the electrical energy from the sources to the storage devices. Therefore, a piezoelectric energy harvesting system can be basically divided into three parts: the energy source, the energy harvesting circuit, and the energy storage device. These three parts are explored in this thesis. / Guan Mingjie. / "September 2006." / Adviser: Wei-Hsin Liao. / Source: Dissertation Abstracts International, Volume: 68-03, Section: B, page: 1822. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2006. / Includes bibliographical references (p. 123-128). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstracts in English and Chinese. / School code: 1307.

Orientador: Nobuo Oki / Banca: Aparecido Augusto de Carvalho / Banca: Tony Inácio da Silva / Resumo: Este trabalho descreve um sistema de extração de potência de power harvesting utilizando transdutores piezelétricos. Com o objetivo de extrair a máxima potência e assim ter um maior rendimento do sistema, foram projetados e testados alguns circuitos eletrônicos. Um circuito de controle com componentes discretos e de baixo consumo foi projetado para controle da chave do retificador chaveado e bias-flip. A energia extraída será utilizada para alimentar um sistema de aquisição de dados e um sensor de temperatura associado a este sistema. O sistema de power harvesting é constituído por uma estrutura mecânica, transdutor piezelétrico, circuito retificador e um conversor CC-CC. Na estrutura mecânica está localizado o transdutor piezelétrico e este transdutor proporciona a conversão de energia mecânica em energia elétrica. Para efeito deste estudo considera-se que o transdutor piezelétrico comporta-se como uma fonte de tensão alternada, que será retificada e armazenada em um supercapacitor, para depois ser utilizada na alimentação do sistema de aquisição de dados. Os conversores CC-CC são utilizados para maximizar a quantidade de energia obtida do transdutor piezelétrico e fornecer tensão ao supercapacitor. No entanto, uma das limitações desses sistemas é a baixa quantidade de energia gerada por esses dispositivos. Assim, para que haja uma minimização das perdas dos circuitos eletrônicos e possa se extrair a máxima potência possível do piezelétrico obtendo um melhor rendimento do sistema, este trabalho investigará a utilização dos circuitos retificadores em ponte, retificador em ponte chaveado, retificador bias-flip e o conversor buck-boost, além de utilizar a energia armazenada para alimentar um sistema de aquisição de dados associados a um sensor de temperatura... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: This work describes several circuits for power extracting of power harvesting systems using piezoelectric transducers. In order to extract the maximum power and to achieve the maximum performance of these systems some electronic circuits were projected and tested. A control circuit with discrete components and low power consumption is designed to control switch of the switch-only and bias-flip rectifier. The goal is that the energy extracted is used to supply power electronic devices. That will be, in this work, a temperature sensor that is placed in a difficult access area. The power harvesting system is composed by a mechanical structure, a piezoelectric transducers, a rectifier and a DC-DC converter. The piezoelectric transducers were placed in the mechanical structure, these transducers are responsible to convert mechanical energy into electrical energy. In this work the piezoelectric transducer was considered an AC voltage source. This voltage will be rectified and then stored in supercapacitor, to be used in electronic circuits. The DC-DC converters were used to achieve maximum power from piezoelectric transducer and to supply voltage to the supercapacitor. However, one of the limitations of these systems is the low amount of power generated by the transducer. This way, it is mandatory to reduce the losses at the electronic components and extract the maximum power possible from the piezoelectric to improve the performance. This work investigates the full-bridge rectifier, switch-only rectifier, bias-flip rectifier and buck- boost converter, besides it aims to use the stored energy to supply a temperature sensor. Using the flip-bias rectifier improves the power up to 200%, and the switch-only rectifier by 150% in relation to full-bridge rectifier. And the efficiency changed from 35% (full-bridge)... (Complete abstract click electronic access below) / Mestre

<p>This thesis focuses on the electromechanical processes of generation and damping of transient waves in bars with attached piezoelectric members. In particular, the influence of amplifier and electrical circuitry on the mechanical waves is of interest.</p><p>A straight bar element containing piezoelectric members is viewed as a linear system with one electrical and two mechanical ports where it interacts with external electrical and mechanical devices through voltage, current, forces and velocities. For the modelling of the piezoelectric bar element (PBE) and its environment, coupled piezoelectric theory is used with allowance for the dynamics of the PBE and attached electrical and mechanical devices.</p><p>Two applications are considered for a PBE that constitutes a part of a long bar, viz. generation and damping of extensional waves. In the first, simulations and experiments were performed when the PBE was driven by a power amplifier. In the second, simulations and experiments were performed when the PBE supplied an output voltage to an external load.</p><p>In the case of wave generation, the influence of amplifier characteristics in terms of DC voltage gain, 3 dB cut-off frequency, output impedance and current constraints on the output voltage and current of the amplifier and the waves generated are studied. Further, generation of waves of prescribed shapes are studied for a specific amplifier. In general, good agreement between simulated and experimental results was obtained.</p><p>In the case of wave damping, the influence of external electrical loads and incident waveforms on reflected and transmitted waves, and on gener-ated voltage, current, electrical power and dissipated energy, are studied. In general, fair agreement between simulated and experimental results was obtained. The fractions of a few percent of wave energy dissipated in the exter-nal load were well below the 50 percent achievable for a harmonic wave under condition of electrical impedance matching.</p>

The validity of the dynamic analysis based on simplified plate model was investigated using of FE-codes ANSYS in the present paper. The simplified clamped multi-layered plate model was first verified by comparison with the exact model. The simply supported plate model was confirmed to be not a suitable model due to its large error as comparing with exact model. Influence of dimensions of laminar diaphragm on nature frequencies was studied. Deflection and voltage response driven by mechanical and electric loads were described. The optimized thickness ratio of PZT layer to SiO₂ and Si layers was given in the paper to obtain the best deflection export of actuator in design. / Singapore-MIT Alliance (SMA)

Pt. 1. Electromechanical impedance matrix--Pt. 2. Electrical driving point impedance and admittance. / by W. Roth. / "July 3, 1947." / Includes bibliographical references. / Army Signal Corps Contract W36-039 sc-32037

Thesis (M.S.)--Brigham Young University. Dept. of Mechanical Engineering, 2005. / Includes bibliographical references (p. 47-50).