Displacement Monitoring of a Bridge Based on BDS Measurement by CEEMDAN-Adaptive Threshold Wavelet Method.

From the viewpoint of BDS bridge displacement monitoring, which is easily affected by background noise and the calculation of a fixed threshold value in the wavelet filtering algorithm, which is often related to the data length. In this paper, a data processing method of Complete Ensemble Empirical Mode Decomposition with Adaptive Noise (CEEMDAN), combined with adaptive threshold wavelet de-noising is proposed. The adaptive threshold wavelet filtering method composed of the mean and variance of wavelet coefficients of each layer is used to de-noise the BDS displacement monitoring data. CEEMDAN was used to decompose the displacement response data of the bridge to obtain the intrinsic mode function (IMF). Correlation coefficients were used to distinguish the noisy component from the effective component, and the adaptive threshold wavelet de-noising occurred on the noisy component. Finally, all IMF were restructured. The simulation experiment and the BDS displacement monitoring data of Nanmao Bridge were verified. The results demonstrated that the proposed method could effectively suppress random noise and multipath noise, and effectively obtain the real response of bridge displacement.

Bright, stable, and tunable solid-state luminescence of carbon nanodot organogels.

Despite the sustained enthusiastic interest in fluorescent carbon nanodots (FCNDs), it is still challenging to achieve bright and widely tunable solid-state luminescence. Herein, organogels embedded with FCNDs were simply synthesized via a one-pot pyrolysis method. Subsequently, the excitation of a single ultraviolet (UV) excitation line results in tunable solid-state luminescence ranging from blue to red with quantum yields (QYs) >14%. In this study, N and S elements were co-doped to regulate the aggregation of FCNDs, which consequently modulated the Stokes shift of the photoluminescence (PL) by managing the degree of photon reabsorption. Notably, without compact aggregations, the dispersions of FCNDs in the organogel matrix indeed render bright fluorescence, which results from the suppression of excessive photon reabsorption and nonradiative resonant energy transfer (NRET).

Effect of same-temperature GaN cap layer on the InGaN/GaN multiquantum well of green light-emitting diode on silicon substrate.

GaN green LED was grown on Si (111) substrate by MOCVD. To enhance the quality of InGaN/GaN MQWs, same-temperature (ST) GaN protection layers with different thickness of 8 Å, 15 Å, and 30 Å were induced after the InGaN quantum wells (QWs) layer. Results show that a relative thicker cap layer is benefit to get InGaN QWs with higher In percent at fixed well temperature and obtain better QW/QB interface. As the cap thickness increases, the indium distribution becomes homogeneous as verified by fluorescence microscope (FLM). The interface of MQWs turns to be abrupt from XRD analysis. The intensity of photoluminescence (PL) spectrum is increased and the FWHM becomes narrow.