By both simulation and experiment, we studied the relationship of the measurement accuracy and the birefringence of the distributed simultaneous strain and temperature sensor using polarization-maintaining fiber Bragg gratings (PANDA-FBGs). The PANDA-FBGs were applied to an optical frequency domain reflectometry (OFDR) which is capable of distributed measurement at high spatial resolution and sampling rate. The simulated results had agreement with the experimental results that the measurement accuracy of both strain and temperature were improved by increasing the birefringence. Additionally, the efficiency of the accuracy improvements decreased when accuracy increased.

This work presents a novel porous activated carbon electrode based on quinoa straw (QSC), which is derived from the Qinghai-Tibet Plateau. The QSC is prepared through simple precarbonization and potassium carbonate (K₂CO₃) activation processes and is intended for use in supercapacitors. The QSC-3 exhibits a high specific capacitance of 469.5 F g^–1 at a current density of 0.5 A g^–1, as well as a high specific surface area of 1802 m² g^–1. Additionally, symmetrical supercapacitors assembled using QSC-3 samples demonstrate a superior energy power density. In a 3 M KOH electrolyte, the energy density can reach 15.0 Wh kg^–1 at a power density of 689.7 W kg^–1. In a 1 M Na₂SO₄ electrolyte, the power density reaches 999.00 W kg^–1, and the energy density is 39.68 Wh kg^–1. Furthermore, the device shows excellent cycle life in both 3 M KOH and 1 M Na₂SO₄ electrolytes, with capacitance retentions of 97.55% and 96.20% after 10 000 cycles, respectively. This study provides an excellent example of utilizing waste quinoa straw to achieve low-cost, high-performance supercapacitor electrode material for sustainable electrochemical energy storage systems.

The high spatial resolution, high accuracy, as well as real-time capability of distributed fiber-optic sensors are important for real-time structural health monitoring. As one of the promising technologies, the optical frequency domain reflectometry (OFDR) based sensors, have attracted lots of attention. Currently, for the demodulation, the conventional method based on short time Fourier transform requires long computational time, while a recent method based on group delay can remarkably improve the calculation speed but has low noise tolerance. In this study, we propose a fast demodulation method which employs the cross correlation, weighted sliding windowed Fourier transform and logistic activation function based thresholding process. This approach keeps good balance among the high spatial resolution, high accuracy, and the real-time capability that is expected to further improve the applicability of OFDR based sensors.

We proposed a quasi-distributed vibration sensing technique using in-line weak reflectors and optical frequency domain reflectometry (OFDR). As a result, we achieved an 8 kHz measurable vibration frequency with a 15–20 cm spatial resolution employing a low repetition rate ($\sim 8\mathrm{Hz}$). Moreover, a measurable frequency of 30 kHz was achieved for a 1.5 m spatial resolution. The ability of the system to determine the frequency and amplitude of several sections vibrating simultaneously is evaluated for different configurations. Because of the simple arrangement, high detectable frequency, and high sensitivity, this approach is expected to be especially well suited for mechanical vibration sensing applications, particularly in medium-sized structures.

We numerically and experimentally demonstrated a high-sensitivity and high-accuracy temperature sensor based on guided acoustic radial modes of forward stimulated Brillouin scattering (FSBS)-based optomechanics in thin-diameter fibers (TDF). The dependence of the FSBS-involved electrostrictive force on the fiber diameter is systematically investigated. As the diameters of the fiber core and cladding decrease, the intrinsic frequency of each activated acoustic mode and corresponding FSBS gain are expected to be accordingly increased, which benefits the significant enhancement of its temperature sensitivity as well as the optimization of the measurement accuracy. In validations, by utilizing TDFs with fiber diameters of 80 µm and 60 µm, the proof-of-concept experiments proved that sensitivities of the TDF-based FSBS temperature sensor with radial modes from R_0,4 to R_0,15 increased from 35.23 kHz/°C to 130.38 kHz/°C with an interval of 8.74 kHz/°C. The minimum measurement error (i.e., 0.15 °C) of the temperature sensor with the 60 µm-TDF is 2.5 times lower than that of the 125 µm-SSMF (i.e., 0.39 °C). The experimental and simulated results are consistent with theoretical predictions. It is believed that the proposed approach with high sensitivity and accuracy could find potential in a wide range of applications such as environmental monitoring, chemical engineering, and cancer detection in human beings.