@article{wang_palagummi_liu_yuan_2013, title={A magnetically levitated vibration energy harvester}, volume={22}, ISSN={["0964-1726"]}, DOI={10.1088/0964-1726/22/5/055016}, abstractNote={In this paper a novel electromagnetic vibration type energy harvester that uses a diamagnetic levitation system is conceptualized, designed, fabricated, and tested. The harvester uses two diamagnetic plates made of pyrolytic graphite between which a cylindrical magnet levitates passively. Two thick cylindrical coils, placed in grooves which are engraved in the pyrolytic graphite plates, are used to convert the mechanical energy into electrical energy efficiently. The geometric configurations of the coils are selected based on the field distribution of the magnet to enhance the efficiency of the harvester. A thorough theoretical analysis is carried out to compare with experimental results. At an input power of 103.45 μW and at a frequency of 2.7 Hz, the harvester generated a power of 0.74 μW with a system efficiency of 0.72%. Both theoretical and experimental results show that this new energy harvesting system can capture low frequency broadband spectra.}, number={5}, journal={SMART MATERIALS AND STRUCTURES}, author={Wang, X. Y. and Palagummi, S. and Liu, L. and Yuan, F. G.}, year={2013}, month={May} }
 @article{liu_yuan_2013, title={Diamagnetic levitation for nonlinear vibration energy harvesting: Theoretical modeling and analysis}, volume={332}, ISSN={["1095-8568"]}, DOI={10.1016/j.jsv.2012.08.004}, abstractNote={This paper provides theoretical modeling and analysis of applying diamagnetic levitation for nonlinear vibration energy harvesting in detail by first identifying potential merits as well as limitations. Based on a magnetic dipole model, analytical analysis is conducted by providing simplified analytical expressions of restoring forces and electromagnetic damping which are then transformed into a hardening spring model and results in a Duffing equation with strong nonlinearity. In addition, constraints on physical geometry are discussed and derived in the view of practical energy harvester design. More importantly, the derivation and discussion extended to multi-well potential suggest that diamagnetic levitation may enable designing an energy harvester that subject to cross-well chaos with a compact volume and wideband responses. Without mechanical damping in any form, diamagnetic levitation may be considered as a promising mechanism for developing vibration energy harvesters with great performance, and the paper provides a technology push on the possibility.}, number={2}, journal={JOURNAL OF SOUND AND VIBRATION}, author={Liu, Lei and Yuan, F. G.}, year={2013}, month={Jan}, pages={455–464} }
 @article{xu_yuan_liu_hu_qiu_2013, title={Performance Prediction and Demonstration of a Miniature Horizontal Axis Wind Turbine}, volume={139}, ISSN={["1943-7897"]}, DOI={10.1061/(asce)ey.1943-7897.0000125}, abstractNote={A miniature wind turbine (MWT) has received great attention recently for powering low-power devices. In this paper, a physics-based comprehensive model for predicting the performance of a miniature horizontal axis wind turbine (MHAWT) was established. The turbine rotor performance was investigated and an approximation of the power coefficient of the turbine rotor was made. Incorporation of the approximation with the equivalent circuit model, which was proposed in accordance with the principles of the MHAWT, in addition to its overall system performance versus the resistive load and ambient wind speed, was predicted. To demonstrate predictive modeling capability, the MHAWT system comprised of commercially available off-the-shelf components was designed and its performance was experimentally tested. The results matched well with those by prediction modeling, which implies that the proposed model holds promise in estimating and optimizing the performance of the MWT.}, number={3}, journal={JOURNAL OF ENERGY ENGINEERING}, author={Xu, Fujun and Yuan, Fuh-Gwo and Liu, Lei and Hu, Jingzhen and Qiu, Yiping}, year={2013}, month={Sep}, pages={143–152} }
 @article{liu_liu_yuan_2012, title={Damage localization using a power-efficient distributed on-board signal processing algorithm in a wireless sensor network}, volume={21}, DOI={10.1088/0964-1726/21/2/025005}, abstractNote={A distributed on-board algorithm that is embedded and executed within a group of wireless sensors to locate structural damages in isotropic plates is presented. The algorithm is based on an energy-decay model of Lamb waves and singular value decomposition (SVD) to determine damage locations. A sensor group consists of a small number of sensors, each of which independently collects wave signals and evaluates wave energy upon an external triggering signal sent from a base station. The energy values, usually a few bytes in length, are then sent to the base station to determine the presence and location of damages. In comparison with traditional centralized approaches in which whole datasets are required to be transmitted, the proposed algorithm yields much less wireless communication traffic, yet with a modest amount of computation required within sensors. Experiments have shown that the algorithm is robust to locate damage for isotropic plate structures and is very power efficient, with more than an order-of-magnitude power saving.}, number={2}, journal={Smart Materials & Structures}, author={Liu, L. and Liu, S. T. and Yuan, F. G.}, year={2012} }
 @article{liu_yuana_2011, title={Nonlinear vibration energy harvester using diamagnetic levitation}, volume={98}, number={20}, journal={Applied Physics Letters}, author={Liu, L. and Yuana, F. G.}, year={2011} }
 @article{liu_yuan_2010, title={A Linear Mapping Technique for Dispersion Removal of Lamb Waves}, volume={9}, ISSN={["1741-3168"]}, DOI={10.1177/1475921709341012}, abstractNote={ A robust signal processing technique using linear mapping for removing dispersion of Lamb waves is presented in this article. Based on the assumption that the dispersion relation characteristic can be adequately approximated by a finite polynomial in the region close to the high wave energy intensity, the dispersion effect begins to reveal in the second-order term of the polynomial. The linear mapping performed in the finite usable frequency domain is to transform the original in priori known dispersion relation into the linear dispersion relation, i.e., truncated the polynomial up to the linear term which is nondispersive. The linear mapping technique does not require the propagation-path lengths and can be applied to the signals consisting of multiple arrivals with the same wave mode or dispersion characteristic. Synthetic and experimental data for isotropic plates with finite in-plane dimensions excited by the fundamental flexural wave mode are shown to demonstrate the robustness of the proposed dispersion removal technique. }, number={1}, journal={STRUCTURAL HEALTH MONITORING-AN INTERNATIONAL JOURNAL}, author={Liu, L. and Yuan, F. G.}, year={2010}, month={Jan}, pages={75–86} }
 @article{liu_yuan_2008, title={Active damage localization for plate-like structures using wireless sensors and a distributed algorithm}, volume={17}, ISSN={["1361-665X"]}, DOI={10.1088/0964-1726/17/5/055022}, abstractNote={Wireless structural health monitoring (SHM) systems have emerged as a promising technology for robust and cost-effective structural monitoring. However, the applications of wireless sensors on active diagnosis for structural health monitoring (SHM) have not been extensively investigated. Due to limited energy sources, battery-powered wireless sensors can only perform limited functions and are expected to operate at a low duty cycle. Conventional designs are not suitable for sensing high frequency signals, e.g. in the ultrasonic frequency range. More importantly, algorithms to detect structural damage with a vast amount of data usually require considerable processing and communication time and result in unaffordable power consumption for wireless sensors. In this study, an energy-efficient wireless sensor for supporting high frequency signals and a distributed damage localization algorithm for plate-like structures are proposed, discussed and validated to supplement recent advances made for active sensing-based SHM. First, the power consumption of a wireless sensor is discussed and identified. Then the design of a wireless sensor for active diagnosis using piezoelectric sensors is introduced. The newly developed wireless sensor utilizes an optimized combination of field programmable gate array (FPGA) and conventional microcontroller to address the tradeoff between power consumption and speed requirement. The proposed damage localization algorithm, based on an energy decay model, enables wireless sensors to be practically used in active diagnosis. The power consumption for data communication can be minimized while the power budget for data processing can still be affordable for a battery-powered wireless sensor. The Levenberg–Marquardt method is employed in a mains-powered sensor node or PC to locate damage. Experimental results and discussion on the improvement of power efficiency are given.}, number={5}, journal={SMART MATERIALS AND STRUCTURES}, author={Liu, L. and Yuan, F. G.}, year={2008}, month={Oct} }