Browsing by Author "Huang, Hai"

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    Estimation of the Vehicle Speed Using Cross-Correlation Algorithms and MEMS Wireless Sensors
    Zhang, Cheng; Shen, Shihui; Huang, Hai; Wang, Linbing (MDPI, 2021-03-02)
    Traffic information is critical for pavement design, management, and health monitoring. Numerous in-pavement sensors have been developed and installed to collect the traffic volume and loading amplitude. However, limited attention has been paid to the algorithm of vehicle speed estimation. This research focuses on the estimation of the vehicle speed based on a cross-correlation method. A novel wireless micro-electromechanical sensor (MEMS), Smartrock is used to capture the triaxial acceleration, rotation, and stress data. The cross-correlation algorithms, i.e., normalized cross-correlation (NCC) algorithm, the smoothed coherence transform (SCOT) algorithm, and the phase transform (PHAT) algorithm, are applied to estimate the loading speed of an accelerated pavement test (APT) and the traffic speed in the field. The signal-noise-ratio (SNR) and the mean relative error (MRE) are utilized to evaluate the stability and accuracy of the algorithms. The results show that both the correlated noise and independent noise have significant influence in the field data. The SCOT algorithm is recommended for speed estimation with reasonable accuracy and stability because of a large SNR value and the lowest MRE value among the algorithms. The loading speed investigated in this study was within 50 km/h and further verification is needed for higher speed estimation.
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    Mutual modulation between surface chemistry and bulk microstructure within secondary particles of nickel-rich layered oxides
    Li, Shaofeng; Jiang, Zhisen; Han, Jiaxiu; Xu, Zhengrui; Wang, Chenxu; Huang, Hai; Yu, Chang; Lee, Sang-Jun; Pianetta, Piero; Ohldag, Hendrik; Qiu, Jieshan; Lee, Jun-Sik; Lin, Feng; Zhao, Kejie; Liu, Yijin (2020-09-07)
    Surface lattice reconstruction is commonly observed in nickel-rich layered oxide battery cathode materials, causing unsatisfactory high-voltage cycling performance. However, the interplay of the surface chemistry and the bulk microstructure remains largely unexplored due to the intrinsic structural complexity and the lack of integrated diagnostic tools for a thorough investigation at complementary length scales. Herein, by combining nano-resolution X-ray probes in both soft and hard X-ray regimes, we demonstrate correlative surface chemical mapping and bulk microstructure imaging over a single charged LiNi0.8Mn0.1Co0.1O2 (NMC811) secondary particle. We reveal that the sub-particle regions with more micro cracks are associated with more severe surface degradation. A mechanism of mutual modulation between the surface chemistry and the bulk microstructure is formulated based on our experimental observations and finite element modeling. Such a surface-to-bulk reaction coupling effect is fundamentally important for the design of the next generation battery cathode materials.