• Energy Research
• 2021-2025close

data_05_d_000.csv - Curve of the RMS values of voltage induced on piezoelectric electrodes for p = 0.183 and randomly selected initial conditions δ = 0.0, κ = 0.5. data_05_d_015.csv - Curve of the RMS values of voltage induced on piezoelectric electrodes for p = 0.183 and randomly selected initial conditions δ = 0.15, κ = 0.5. data_05_d_030.csv - Curve of the RMS values of voltage induced on piezoelectric electrodes for p = 0.183 and randomly selected initial conditions δ = 0.3, κ = 0.5. data_05_d_060.csv - Curve of the RMS values of voltage induced on piezoelectric electrodes for p = 0.183 and randomly selected initial conditions δ = 0.6, κ = 0.5. data_06r_o_19.csv - The orbits of the periodic solutions presented in Fig. 6(a) ω = 1.9, Poincaré points = 2. data_06b_o_19.csv - The orbits of the periodic solutions presented in Fig. 6(a) ω = 1.9, Poincaré points = 3. data_06r_o_21.csv - The orbits of the periodic solutions presented in Fig. 6(b) ω = 2.1, Poincaré points = 2. data_06g_o_21.csv - The orbits of the periodic solutions presented in Fig. 6(b) ω = 2.1, Poincaré points = 3. data_06b_o_21.csv - The orbits of the periodic solutions presented in Fig. 6(b) ω = 2.1, Poincaré points = 9. data_06r_o_26.csv - The orbits of the periodic solutions presented in Fig. 6(c) ω = 2.6, Poincaré points = 2. data_06b_o_26.csv - The orbits of the periodic solutions presented in Fig. 6(c) ω = 2.6, Poincaré points = 3. data_06g_o_26.csv - The orbits of the periodic solutions presented in Fig. 6(c) ω = 2.6, Poincaré points = 6. data_06r_o_38.csv - The orbits of the periodic solutions presented in Fig. 6(d) ω = 3.8, Poincaré points = 3. data_06b_o_38.csv - The orbits of the periodic solutions presented in Fig. 6(d) ω = 3.8, Poincaré points = 4. data_06g_o_38.csv - The orbits of the periodic solutions presented in Fig. 6(d) ω = 3.8, Poincaré points = 5. data_06lb_o_38.csv - The orbits of the periodic solutions presented in Fig. 6(d) ω = 3.8, Poincaré points = 7. data_06p_o_38.csv - The orbits of the periodic solutions presented in Fig. 6(d) ω = 3.8, Poincaré points = 9. data_07b_d_015.csv - Numerical results showing the influence of potential asymmetry on the probability of occurrence of particular solutions for δ = 0.15. data_07g_d_030.csv - Numerical results showing the influence of potential asymmetry on the probability of occurrence of particular solutions for δ = 0.30. data_07lb_d_06.csv - Numerical results showing the influence of potential asymmetry on the probability of occurrence of particular solutions for δ = 0.60. data_07r_d_000.csv - Numerical results showing the influence of potential asymmetry on the probability of occurrence of particular solutions for δ = 0.0. This repository contains the results of numerical simulations of a nonlinear bistable system for harvesting energy from ambient vibrating mechanical sources. Detailed model tests were carried out on an inertial energy harvesting system consisting of a piezoelectric beam with additional springs attached. The mathematical model was derived using the bond graph approach. Depending on the spring selection, the shape of the bistable potential wells was modified including the removal of wells’ degeneration. Consequently, the broken mirror symmetry between the potential wells led to additional solutions with corresponding voltage responses. The probability of occurrence for different high voltage/large orbit solutions with changes in potential symmetry was investigated. In particular, the periodicity of different solutions with respect to the harmonic excitation period were studied and compared in terms of the voltage output. The results showed that a large orbit period-6 subharmonic solution could be stabilized while some higher subharmonic solutions disappeared with the increasing asymmetry of potential wells. Changes in frequency ranges were also observed for chaotic solutions.

The subject of the research contained in this repository is a new design solution for an energy harvesting system resulting from the combination of a quasi-zero-stiffness energy harvester and a two-stage flexible cantilever beam. Numerical tests were divided into two main parts-analysis of the dynamics of the system due to periodic, quasiperiodic, and chaotic solutions and the efficiency of energy generation. The results of numerical simulations were limited to zero initial conditions, as they are the natural position of the static equilibrium. The repository compares graphically the energy efficiency for the selected range of the dimensionless excitation frequency. For this purpose, three cases of piezoelectric mounting were presented on figures - only on the first stage of the beam, on the second and both stages. The analysis has been carried out with the use of diagrams showing difference of the effective values of the voltage induced on the piezoelectric electrodes. The results indicate that for effective energy harvesting, it is advisable to attach piezoelectric energy transducers to each step of the beam despite possible asynchronous vibrations.

In this paper, we describe a measurement procedure to fully characterise a novel vibration energy harvester operating in the ultra-low-frequency range. The procedure, which is more thorough than those usually found in the literature, comprises three main stages: modelling, experimental characterisation and parameter identification. Modelling is accomplished in two alternative ways, a physical model (white box) and a mixed one (black box), which model the magnetic interaction via Fourier series. The experimental measurements include not only the input (acceleration)–output (energy) response but also the (internal) dynamic behaviour of the system, making use of a synchronised image processing and signal acquisition system. The identification procedure, based on maximum likelihood, estimates all the relevant parameters to characterise the system to simulate its behaviour and helps to optimise its performance. While the method is custom-designed for a particular harvester, the comprehensive approach and most of its procedures can be applied to similar harvesters.

The recent rapid development of smart electronic devices, including wearable electronic devices, Internet of Things (IoT) devices, implantable medical devices and remote smart monitors, has raised great research interests on optimising battery power consumption in small-scaled and remotely operational electronic components. For the past ten years, there has been many research works in vibration-based energy harvesting, i.e., converting ambient vibration sources into electrical energy via different transduction methods. In dealing with environmental vibration sources, the most pressing issue for vibration-based energy harvesters (VEHs) from mechanical and structural perspectives is whether the device can efficiently output an optimised power level under realistic (i.e., non-stationary, time-dependent, distributed in frequency spectrum, etc.) excitation sources. Additionally, the performance of VEHs is also restricted in size, complexity of design, and power density issues. Under such design criteria, introducing nonlinearities into VEHs attracted wide attention. This research work aims to investigate the bandwidth performance of vibration-based energy harvesting by subjecting nonlinear phenomena/techniques with internal and externally induced dynamic behaviours into the systems, hence broadening the operational bandwidth and optimising the power level under a wide range of frequencies. The outcomes of this research work yield five peerreviewed journal papers and several international conference papers. The five journal papers are presented in five chapters (Chapter 3 to Chapter 7) as the main contributions of this thesis. Paper 1 presents a magnetic VEH using combined primary and parametric resonances. In order to merge the resonant regions of fundamental primary resonance and parametric resonance as one continuously operational bandwidth, the motion limiter is utilised to induce external hardening effects that aim to eliminate the off-resonance regime between the two resonances. Theoretical investigations, ...

The resilience of power infrastructure against environmental challenges, particularly wind-induced vibrations, is crucial for ensuring the reliability and longevity of overhead power lines. This dissertation extends the development of the Mobile Damping Robot (MDR) as a novel solution for mitigating wind-induced vibrations through adaptive repositioning and energy harvesting capabilities. Through comprehensive experimental and numerical analyses, the research delineates the design, optimization, and application of the MDR, encompassing its dynamic adaptability and energy harvesting potential in response to varying wind conditions. The study begins with the development and validation of a linearized model for the MDR, transitioning to advanced nonlinear models that more accurately depict the complex interactions between the robot, cable system, and environmental forces. A global stability analysis provides crucial insights into the operational limits and safety parameters of the system. Further, the research explores a multi-degree-of-freedom system model to evaluate the MDR's efficacy in real-world scenarios, emphasizing its energy harvesting efficiency and potential for sustainable operation. Findings from this research show the clear promise for the development of the MDR with the consideration of the nonlinear dynamics in play between the robot, the cable, and the wind. This work lays a foundational framework for future innovations in infrastructure maintenance, paving the way for the practical implementation of mobile damping technologies in energy systems. Doctor of Philosophy Across the United States, over 160,000 miles of power lines crisscross the landscape, powering everything from small homes to large industrial complexes. These critical infrastructures, however, are constantly battered by the elements, particularly by strong winds capable of inducing Aeolian vibrations. Such vibrations lead to oscillations in the power lines due to wind forces, potentially causing severe structural damage, compromising public safety, and incurring considerable economic costs. In response to these challenges, various mitigation strategies have been employed. Traditional methods include regular inspections carried out by foot patrols, helicopters, or sophisticated inspection robots, though these approaches are notably resource-intensive and costly. Additionally, mechanical devices like Stockbridge dampers are utilized to dampen the vibrations, but they suffer from efficiency issues when misaligned with the vibration nodes. This dissertation extends the study to an innovative solution to overcome these limitations: a mobile damping robot designed to navigate along power lines and autonomously position itself at the points of highest vibration amplitude, thereby optimizing vibration dampening. This study delves into the feasibility and effectiveness of such a solution, supported by thorough numerical simulations. The aim is to demonstrate how this advanced approach could redefine maintenance strategies for power lines, enhancing their resilience against wind-induced vibrations and reducing the reliance on laborious inspection methods and static damping devices with limited efficiency.

The use of machines that employ mechanical vibrations that transmit stimuli to the whole body through a gravitational load to the neuromuscular system increases muscular grip strength and body balance. Oxygen consumption (VO2) wase valuated using mechanical vibration platforms in healthy individuals to check their caloric expenditure compared to other forms of physical exercise and to determine its impact on the control of body overweight. 42 men aged20.28 ± 2.9 years, height 171.35 ± 7.01 cm, weight 67.47 ± 8.75 kg were measured. The Modified Bruce test wasapplied to assess VO2 max and a Bioshaker® Compact® model vibrating platform. Each subject remained for15min in a static position at a vibration of 2,500 cycles per minute, recording VO2 at 5, 10 and 15 min of the test.VO2 max. it was 3.01 ± 0.4 L/min, while on the vibrating platform it was 1.03 ± 0.33. The use of vibration platformsgenerates limited energy expenditure to create significant changes in body weight and consumption of fatty acids toproduce energy. Actividad Física y Deporte

Unwanted vibrations are all around us in our daily life. These vibrations can effectively be converted into electrical power through capacitive device. Even though the amount of power generated is small ([mu]W), it is still sufficient to drive certain devices, such as devices in the field of Micro Electro Mechanical System (MEMS). We call these functional devices "self-powered devices". This dissertation describes design, modeling, analysis, dynamic simulation and experimental testing of MEMS variable capacitors which are used for power harvesting based on external vibration. More specifically, it includes the electrostatic force and the forces provided by the stopper designed to prevent direct impact between capacitive plates. To more accurately reflect the status of power harvesting, rocking instability is discussed as well. However, the onset of rocking instability leads to more complicated dynamic phenomena. This dissertation not only introduces equation theory derivation and dynamic behaviors of the MEMS capacitive harvester, but also presents a comparison of power harvesting at broad frequencies and different amplitudes. These conclusions are helpful for the design of high efficiency "self-powered" MEMS capacitive power harvester.

The demand for sustainable and non-traditional sources of energy increases every day to power up different electronic equipment whether it's portable low-power devices, non-accessible sensors, wearable electronics, implantable medical devices, and even for big scale applications that can contribute to the energy demand on a public level. Energy harvesting from vibrations offers an ideal source of energy, since it's renewable and prevailing, where kinetic energy that can be harvested is abundant in nature. \newline In this proposal, a novel electromagnetic transduction mechanism is introduced that can be used in harvesting low-frequency vibrations below 10 Hz, which makes it suitable to harvest motion from human locomotion, moving vehicles, and structures like buildings, bridges and streets. The transduction mechanism developed induces a current in a coil by disrupting the electromagnetic field in the vicinity of a stationary coil wound around a hollow track (tube) made of non-conducting or conducting (copper) material, where a ball made of ferromagnetic material is moving freely along the track cutting the field lines and induces current in the coil. Prototypes embodying the harvesting mechanism were fabricated and tested to identify the different system parameters, frequency-responses and characterize the harvester in order to derive a representative mathematical model. The performance of the energy harvester was measured and characterized in terms of output power, power density and tunability. Where the prototypes fabricated demonstrated a capability to harvest energy at low-frequencies in the range of 6.54-12.72 Hz , with a 3 dB harvesting bandwidth ranging between 1.32 Hz to 5.8 Hz, and generated output power up to 154 micro-Watt. The proposed transduction mechanism demonstrated a strong flexibility that allows tuning the center frequency magnetically, without the need to modify the mechanical design, in order to take advantage of this feature, an intelligent fuzzy tuner design is proposed, supported with ...