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1 – 10 of 718Chengdong Yuan, Siyang Hu and Tamara Bechtold
Based on the framework of Krylov subspace-based model order reduction (MOR), compact models of the piezoelectric energy harvester devices can be generated. However, the stability…
Abstract
Purpose
Based on the framework of Krylov subspace-based model order reduction (MOR), compact models of the piezoelectric energy harvester devices can be generated. However, the stability of reduced piezoelectric model often cannot be preserved. In previous research studies, “MOR after Schur,” “Schur after MOR” and “multiphysics structure preserving MOR” methods have proven successful in obtaining stable reduced piezoelectric energy harvester models. Though the stability preservation of “MOR after Schur” and “Schur after MOR” methods has already been mathematically proven, the “multiphysics structure preserving MOR” method was not. This paper aims to provide the missing mathematical proof of “multiphysics structure preserving MOR.”
Design/methodology/approach
Piezoelectric energy harvesters can be represented by system of differential-algebraic equations obtained by the finite element method. According to the block structure of its system matrices, “MOR after Schur” and “Schur after MOR” both perform Schur complement transformations either before or after the MOR process. For the “multiphysics structure preserving MOR” method, the original block structure of the system matrices is preserved during MOR.
Findings
This contribution shows that, in comparison to “MOR after Schur” and “Schur after MOR” methods, “multiphysics structure preserving MOR” method performs the Schur complement transformation implicitly, and therefore, stabilizes the reduced piezoelectric model.
Originality/value
The stability preservation of the reduced piezoelectric energy harvester model obtained through “multiphysics structure preserving MOR” method is proven mathematically and further validated by numerical experiments on two different piezoelectric energy harvester devices.
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Elvio Bonisoli, Nicoló Manca and Maurizio Repetto
– The purpose of this paper is to describe an electro-mechanical lumped parameters model used for the simulation of an energy harvester device.
Abstract
Purpose
The purpose of this paper is to describe an electro-mechanical lumped parameters model used for the simulation of an energy harvester device.
Design/methodology/approach
The model is taking into account the main features of both mechanical and electromagnetic phenomena keeping the computational burden as low as possible to insert it inside an optimisation loop.
Findings
The simulation tool is then used to design the main parameters of an energy harvester able to supply a computer mouse by converting mechanical energy provided by the computer user.
Originality/value
The use of a multi-physics analysis tool inside one optimisation loop is a difficult task that requires the honing of all the modules involved in the performance evaluation. The developed approach has shown to be reliable, efficient and has been a key factor in the development of a new product.
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This paper aims to study a power management circuit for a piezoelectric vibration energy harvester. It presents how to accumulate energy and provide regulated DC voltage for…
Abstract
Purpose
This paper aims to study a power management circuit for a piezoelectric vibration energy harvester. It presents how to accumulate energy and provide regulated DC voltage for practical applications.
Design/methodology/approach
Energy storage and extraction circuit are proposed. While the storage stage consists of a full wave rectifier and a storage capacitor, the extraction stage includes a voltage comparator and regulator, which may provide the load steady DC voltage when the voltage of the storage capacitor is higher than the threshold.
Findings
The numerical analysis and experimental results indicate that it takes a longer time to charge to a specified voltage for the greater storage capacitor and the net charge flowing into the storage capacitor during each period decreases when the voltage of the storage capacitor is higher. The higher threshold voltage of the capacitor has lower harvesting efficiency owing to the rate of charging of the storage capacitor slowing down over time.
Research limitations/implications
Because of the chosen research method, the power management circuit is only suitable for the piezoelectric vibration energy harvester under resonant conditions.
Practical implications
This study includes practically useful applications for users to build a power management circuit for piezoelectric energy harvester.
Originality/value
This study presents results that the charging efficiency of the storage circuit is relative to the storage capacitor and the threshold voltage.
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The paper aims to analyze the behavior of the Galfenol rods under bending conditions that are employed in a vibration energy harvester by illustrating the spatial variations in…
Abstract
Purpose
The paper aims to analyze the behavior of the Galfenol rods under bending conditions that are employed in a vibration energy harvester by illustrating the spatial variations in stress and magnetic field.
Design/methodology/approach
This paper describes a 3‐D static finite element model of magnetostrictive materials, considering magnetic and elastic boundary value problems that are bidirectionally coupled through stress and field dependent variables. The finite element method is applied to a small vibration‐driven generator of magnetostrictive type employing Iron‐Gallium alloy (Galfenol).
Findings
The 3‐D static finite element modeling presented here highlights the spatial variations in magnetic field and relative permeability due to the corresponding stress distribution in the Galfenol rods subjected to transverse load. The numerical calculations show that about 1.1 T change in magnetic flux density is achieved which demonstrates the effectiveness of the inspected vibration‐driven generator in voltage generation and energy harvesting. The model predictions agree with the experimental results and are coherent with the magnetostriction phenomenon.
Originality/value
This paper fulfils the behavior analysis of Galfenol rods under transverse load that includes both compression and tension. The compressive and tensile stresses contributions to change in magnetic flux densities in the Galfenol rods were calculated by which the effectiveness of the inspected vibration‐driven generator in voltage generation and energy harvesting is demonstrated.
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– This paper aims to provide details of recent energy harvesting developments.
Abstract
Purpose
This paper aims to provide details of recent energy harvesting developments.
Design/methodology/approach
Following an introduction, this paper first considers mechanical and biomechanical energy harvesting developments. It then discusses hybrid harvesting technologies and self-powered sensors and concludes with a brief discussion.
Findings
Energy harvesting is the topic of a major research effort and growing commercial activities. Several advanced technologies are being used to develop sophisticated devices to harvest individual or combined energy sources. These developments are expected to play a central role in many emerging sensor markets.
Originality/value
This paper provides technical details of a selection of recently reported energy harvesting developments.
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Xiaorui Yang, Ying Chen, Yan Zhang and Wenrong Yang
The purpose of this study is to develop a friction-type energy-harvesting device based on magnetic liquids (MLs). This MLs energy-harvesting device combines MLs with a…
Abstract
Purpose
The purpose of this study is to develop a friction-type energy-harvesting device based on magnetic liquids (MLs). This MLs energy-harvesting device combines MLs with a triboelectric nanogenerator (TENG), reducing the friction thermal effect to improve the conversion efficiency and working frequency band.
Design/methodology/approach
First, the motion equation of the MLs is calculated using the Bernoulli and fluid continuity equations. Second, the sloshing process of an ML in a container is simulated using the finite element simulation method, and the magnetic field distribution of the permanent magnet in the MLs is calculated. Then, the output characteristic of the ML-TENG is deduced theoretically, and the influencing factors of the output voltage are analyzed. Finally, the output voltage of the MLs energy-harvesting device was tested experimentally, and the influence of the magnetic field on the output voltage was tested.
Findings
This study proposes a vibration energy harvesting device based on MLs. The output voltage of the device was obtained through simulation and experimental tests, and the effect of the magnetic field on the output voltage was obtained.
Originality/value
This study provides a method to convert vibration energy into electrical energy using the magnetic response and fluid characteristics of MLs, and the availability of the device is verified by simulation and experiment. This energy-harvesting device exhibits less loss and a more sensitive response.
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Serhat Yüksel and Gözde Gülseven Ubay
No carbon gas is released into the atmosphere in electricity production with wind energy. Therefore, this type of energy is significantly environmentally friendly. On the other…
Abstract
No carbon gas is released into the atmosphere in electricity production with wind energy. Therefore, this type of energy is significantly environmentally friendly. On the other hand, thanks to wind energy investments, a country can produce its own energy. This reduces the country’s foreign dependency on energy. Due to these positive aspects, increasing wind energy investments is very important for both the social and economic development of the country. The aim of this study is to define the most appropriate government support to improve wind energy investments. In this context, four different criteria are defined in this regard by making a detailed literature review. In the analysis process, fuzzy AHP methodology is considered. Within this framework, the comparative evaluations of three different experts are obtained. The findings indicate that providing loans with low-interest rate is the most appropriate government support for the wind energy investors. Additionally, it is also defined that tax deduction is another important issue for this purpose. However, it is also identified that appropriate location supply and purchase guarantee of the product produced have lower importance in comparison with the others. It is strongly recommended that governments should provide loans to the wind energy investors. This strategy can minimize the problem of high initial cost so that it can be much easier to attract the attention of the investors.
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The paper aims to provide a technical review of new and emerging power sources and their application to sensors.
Abstract
Purpose
The paper aims to provide a technical review of new and emerging power sources and their application to sensors.
Design/methodology/approach
This is the second part of a two‐part paper. Following a brief introduction, recent developments and research into fuel cell, energy harvesting, microgenerator and wireless power transmission technologies are considered.
Findings
All of these technologies are the topic of a major research effort and offer prospects to power future generations of sensors. Several pose strong competition to rechargeable batteties.
Originality/value
The paper provides a detailed insight into new and improved sensor power sources.
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Baiping Yan, Dazhuo Huang, Junjie Hong and Chengming Zhang
This paper aims to present the design and fabrication of a rotary magnetostrictive energy generator, using to harvest the rotation energy of human knee joint.
Abstract
Purpose
This paper aims to present the design and fabrication of a rotary magnetostrictive energy generator, using to harvest the rotation energy of human knee joint.
Design/methodology/approach
A rotary magnetostrictive energy generator is presented in this paper. The harvester consists of six movable flat Terfenol-D rods, surround by the picked-up coils respective, and alternate permanent magnet (PM) array fixed in the upper cover of the stator. The harvester rotates like as a stepper motor, which has rotary electromagnetic power generating effect and impacted magnetostrictive power generating effect in its rotation. Modeling and simulation are used to validate the concept. A prototype of harvester is fabricated and subjected to the experimental characterization.
Findings
The size of proposed structure is control as 77 cm3, and its mass is about 0.21 kg. Huge induced voltage generated in the short-time impact situation, and that induced voltage in the harvester can up to 18.6 V at 0.32 s stepper rotation. Also, the presented harvester has good harvesting effects at low frequency human walking situation, which is suitable to be used for future researches of wearable knee joint applications.
Originality/value
A new concept of magnetostrictive harvester is presneted, which will be benefit for the application of human knee joint wearable. Also, this concept will give us more idea for collection of human movement energy.
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