@article{ke_wu_lu_2019, title={A Real-Time Greedy-Index Dispatching Policy for Using PEVs to Provide Frequency Regulation Service}, volume={10}, ISSN={["1949-3061"]}, DOI={10.1109/TSG.2017.2754241}, abstractNote={This paper presents a real-time greedy-index dispatching policy (GIDP) for using plug-in electric vehicles (PEVs) to provide frequency regulation services. A new service cost allocation mechanism is proposed to award PEVs based on the amount of service they provided, while considering compensations for delayed-charging and reduction of battery lifetime due to participation of the service. The GIDP transforms the optimal dispatch problem from a high-dimensional space into an 1-D space while preserving the solution optimality. When solving the transformed problem in real-time, the global optimality of the GIDP solution can be guaranteed by mathematically proved “indexability.” Because the GIDP index can be calculated upon the PEV’s arrival and used for the entire decision making process till its departure, the computational burden is minimized and the complexity of the aggregator dispatch process is significantly reduced. Simulation results are used to evaluate the proposed GIDP, and to demonstrate the potential profitability from providing frequency regulation service by using PEVs.}, number={1}, journal={IEEE TRANSACTIONS ON SMART GRID}, author={Ke, Xinda and Wu, Di and Lu, Ning}, year={2019}, month={Jan}, pages={864–877} }
 @article{johnson_kim_zhang_wu_jiang_2014, title={High-temperature acoustic emission sensing tests using a yttrium calcium oxyborate sensor}, volume={61}, DOI={10.1109/tuffc.2014.6805694}, abstractNote={Piezoelectric materials have been broadly utilized in acoustic emission sensors, but are often hindered by the loss of piezoelectric properties at temperatures in the 500°C to 700°C range or higher. In this paper, a piezoelectric acoustic emission sensor was designed and fabricated using yttrium calcium oxyborate (YCOB) single crystals, followed by Hsu-Nielsen tests for high-temperature (>700°C) applications. The sensitivity of the YCOB sensor was found to have minimal degradation with increasing temperature up to 1000°C. During Hsu-Nielsen tests with a steel bar, this YCOB acoustic sensor showed the ability to detect zero-order symmetric and antisymmetric modes at 30 and 120 kHz, respectively, as well as distinguish a first-order antisymmetric mode at 240 kHz at elevated temperatures up to 1000°C. The frequency characteristics of the signal were verified using a finite-element model and wavelet transformation analysis.}, number={5}, journal={IEEE Transactions on Ultrasonics Ferroelectrics and Frequency Control}, author={Johnson, J. A. and Kim, K. and Zhang, S. J. and Wu, D. and Jiang, X. N.}, year={2014}, pages={805–814} }
 @article{ma_guo_wu_geng_jiang_2013, title={Design, Fabrication, and Characterization of a Single-Aperture 1.5-MHz/3-MHz Dual-Frequency HIFU Transducer}, volume={60}, ISSN={["1525-8955"]}, DOI={10.1109/tuffc.2013.2724}, abstractNote={High-intensity focused ultrasound (HIFU) treatment efficiency is critical in maximizing the hyperthermia and reducing the surgery time. In this paper, a single-aperture, 1.5 MHz/3 MHz dual-frequency HIFU transducer was designed, fabricated, and characterized for tissue ablation enhancement. Double PZT-2 layers were configured in serial and dual-frequency ultrasound waves can be concurrently generated by exciting one of the PZT-2 layers. Impulse responses from the prototype showed that the wave amplitudes at 1.5 and 3 MHz were about the same, and both are more than 12 dB larger than those of higher orders of harmonics. Tissue ablation tests demonstrated that higher temperature rise can be achieved with dual-frequency ultrasound than with single-frequency ablation at the same acoustic power.}, number={7}, journal={IEEE TRANSACTIONS ON ULTRASONICS FERROELECTRICS AND FREQUENCY CONTROL}, author={Ma, Jianguo and Guo, Sijia and Wu, Di and Geng, Xuecang and Jiang, Xiaoning}, year={2013}, month={Jul}, pages={1519–1529} }
 @article{johnson_kim_zhang_wu_jiang_2013, title={High-temperature (> 1000 degrees C) acoustic emission sensor}, volume={8694}, ISSN={["1996-756X"]}, DOI={10.1117/12.2009301}, abstractNote={Piezoelectric crystals have shown promising results as acoustic emission sensors, but are often hindered by the loss of electric properties above temperatures in the 500-700°C range. Yttrium calcium oxyborate, (YCOB), however, is a promising high temperature piezoelectric material due to its high resistivity at high temperatures and its relatively stable electromechanical and piezoelectric properties across a broad temperature range. In this paper, a piezoelectric acoustic emission sensor was designed, fabricated, and tested for use in high temperature applications using a YCOB single crystal. An acoustic wave was generated by a Hsu-Nielsen source on a stainless steel bar, which then propagated through the substrate into a furnace where the YCOB acoustic emission sensor is located. Charge output of the YCOB sensor was collected using a lock-in charge amplifier. The sensitivity of the YCOB sensor was found to have small to no degradation with increasing temperature up to 1000 °C. This oxyborate crystal showed the ability to detect zero order symmetric and antisymmetric modes, as well as distinguishable first order antisymmetric modes at elevated temperatures up to 1000 °C.}, journal={NONDESTRUCTIVE CHARACTERIZATION FOR COMPOSITE MATERIALS, AEROSPACE ENGINEERING, CIVIL INFRASTRUCTURE, AND HOMELAND SECURITY 2013}, author={Johnson, Joseph A. and Kim, Kyungrim and Zhang, Shujun and Wu, Di and Jiang, Xiaoning}, year={2013} }