@inproceedings{kulshrestha_wang_chow_lukic_2009, title={Intelligent energy management system simulator for PHEVs at municipal parking deck in a smart grid environment}, booktitle={2009 ieee power & energy society general meeting, vols 1-8}, author={Kulshrestha, P. and Wang, L. and Chow, M. Y. and Lukic, S.}, year={2009}, pages={2157–2162} }
@article{wang_yuan_2008, title={Vibration energy harvesting by magnetostrictive material}, volume={17}, ISSN={["1361-665X"]}, DOI={10.1088/0964-1726/17/4/045009}, abstractNote={A new class of vibration energy harvester based on magnetostrictive material (MsM), Metglas 2605SC, is designed, developed and tested. It contains two submodules: an MsM harvesting device and an energy harvesting circuit. Compared to piezoelectric materials, the Metglas 2605SC offers advantages including higher energy conversion efficiency, longer life cycles, lack of depolarization and higher flexibility to survive in strong ambient vibrations. To enhance the energy conversion efficiency and alleviate the need of a bias magnetic field, Metglas ribbons are transversely annealed by a strong magnetic field along their width direction. To analyze the MsM harvesting device a generalized electromechanical circuit model is derived from Hamilton’s principle in conjunction with the normal mode superposition method based on Euler–Bernoulli beam theory. The MsM harvesting device is equivalent to an electromechanical gyrator in series with an inductor. In addition, the proposed model can be readily extended to a more practical case of a cantilever beam element with a tip mass. The energy harvesting circuit, which interfaces with a wireless sensor and accumulates the harvested energy into an ultracapacitor, is designed on a printed circuit board (PCB) with plane dimension 25 mm × 35 mm. It mainly consists of a voltage quadrupler, a 3 F ultracapacitor and a smart regulator. The output DC voltage from the PCB can be adjusted within 2.0–5.5 V. In experiments, the maximum output power and power density on the resistor can reach 200 µW and 900 µW cm−3, respectively, at a low frequency of 58 Hz. For a working prototype under a vibration with resonance frequency of 1.1 kHz and peak acceleration of 8.06 m s−2 (0.82 g), the average power and power density during charging the ultracapacitor can achieve 576 µW and 606 µW cm−3, respectively, which compete favorably with piezoelectric vibration energy harvesters.}, number={4}, journal={SMART MATERIALS AND STRUCTURES}, author={Wang, Lei and Yuan, F. G.}, year={2008}, month={Aug} }
@article{wang_yuan_2007, title={Active damage localization technique based on energy propagation of Lamb waves}, volume={3}, ISSN={["1738-1584"]}, DOI={10.12989/sss.2007.3.2.201}, abstractNote={An active damage detection technique is introduced to locate damage in an isotropic plate using Lamb waves. This technique uses a time-domain energy model of Lamb waves in plates that the wave amplitude inversely decays with the propagation distance along a ray direction. Accordingly the damage localization is formulated as a least-squares problem to minimize an error function between the model and the measured data. An active sensing system with integrated actuators/sensors is controlled to excite/receive mode of Lamb waves in the plate. Scattered wave signals from the damage can be obtained by subtracting the baseline signal of the undamaged plate from the recorded signal of the damaged plate. In the experimental study, after collecting the scattered wave signals, a discrete wavelet transform (DWT) is employed to extract the first scattered wave pack from the damage, then an iterative method is derived to solve the least-squares problem for locating the damage. Since this method does not rely on time-of-flight but wave energy measurement, it is more robust, reliable, and noise-tolerant. Both numerical and experimental examples are performed to verify the efficiency and accuracy of the method, and the results demonstrate that the estimated damage position stably converges to the targeted damage.}, number={2}, journal={SMART STRUCTURES AND SYSTEMS}, author={Wang, Lei and Yuan, F. G.}, year={2007}, month={Apr}, pages={201–217} }
@article{wang_yuan_2007, title={Group velocity and characteristic wave curves of Lamb waves in composites: Modeling and experiments}, volume={67}, ISSN={["0266-3538"]}, DOI={10.1016/j.compscitech.2006.09.023}, abstractNote={The propagation characteristics of Lamb waves in composites, with emphasis on group velocity and characteristic wave curves, are investigated theoretically and experimentally. In particular, the experimental study focuses on the existence of multiple higher-order Lamb wave modes that can be observed from piezoelectric sensors by the excitation of ultrasonic frequencies. Using three-dimensional (3-D) elasticity theory, the exact dispersion relations governed by transcendental equations are numerically solved for an infinite number of possible wave modes. For symmetric laminates, a robust method by imposing boundary conditions on the mid-plane and top surface is proposed to separate symmetric and anti-symmetric wave modes. A new semi-exact method is developed to calculate group velocities of Lamb waves in composites. Meanwhile, three characteristic wave curves: velocity, slowness, and wave curves are adopted to analyze the angular dependency of Lamb wave propagation. The dispersive and anisotropic behavior of Lamb waves in a two different types of symmetric laminates is studied in detail theoretically. In the experimental study, two surface-mounted piezoelectric actuators are excited either symmetric or anti-symmetric wave modes with narrowband signals, and a Gabor wavelet transform is used to extract group velocities from arrival times of Lamb wave received by a piezoelectric sensor. In comparison with the results from the theory and experiment, it is confirmed that multiple higher-order Lamb waves can be excited from piezoelectric actuators and the measured group velocities agree well with those from 3-D elasticity theory.}, number={7-8}, journal={COMPOSITES SCIENCE AND TECHNOLOGY}, author={Wang, Lei and Yuan, F. G.}, year={2007}, month={Jun}, pages={1370–1384} }
@article{fritts_wang_tolson_2006, title={Mean and gravity wave structures and variability in the Mars upper atmosphere inferred from Mars Global Surveyor and Mars Odyssey aerobraking densities}, volume={111}, number={A12}, journal={Journal of Geophysical Research. Space Physics}, author={Fritts, D. C. and Wang, L. and Tolson, R. H.}, year={2006}, pages={A12304} }
@article{wang_yuan_2005, title={Damage identification in a composite plate using prestack reverse-time migration technique}, volume={4}, ISSN={["1741-3168"]}, DOI={10.1177/1475921705055233}, abstractNote={Migration technique, which is normally used in geophysical prospecting, is proposed to locate and image multiple delamination damages in a laminated composite plate. In this simulation study, an active diagnostic system with a linear array of actuators/sensors is used to excite/receive the lowest mode of flexural waves in the laminate. The wavefield scattered from the damages and sensor array data are synthesized using a two-dimensional explicit finite difference scheme to model wave propagation in the laminate based on the Mindlin plate theory. A prestack reverse-time migration technique is then adopted to interpret the synthetic sensor array data and to visualize the damages. The phase and group velocities of flexural waves in the composite plate are derived from the dispersion relations, and subsequently an excitation-time imaging condition specifically for migration of waves in the plate is introduced based on ray tracing and group velocity. Then the prestack reverse-time migration is performed using the same finite difference scheme to back-propagate the scattered energy to the damages. During the migration process, the laminate is imaged in terms of velocity of the transverse deformation. The locations and dimensions of the damages can be visually displayed. Simulated results demonstrate that multiple delamination damages can be successfully identified and the resulting image correlates well with the target damages.}, number={3}, journal={STRUCTURAL HEALTH MONITORING-AN INTERNATIONAL JOURNAL}, author={Wang, L and Yuan, FG}, year={2005}, month={Sep}, pages={195–211} }