Brillouin scattering based fiber optic strain sensor is used to measure distributed strain profile of a structure for structural health monitoring. A distributed strain profile is derived from the Brillouin spectrum peaks but error is induced when a local strain change occurs in a distance scale smaller than the spatial resolution. In this study, a new algorithm is proposed to reconstruct a Brillouin spectrum by eliminating low qualified data from the raw spectrum data. This is achieved by evaluating the strain gradient profile and statistically decomposing the power, width, and peak frequency of the raw spectrum data. This algorithm is versatile because it can be applied to various strain shapes and magnitudes. The reliability of the algorithm is verified experimentally by showing that the error of the strain profile obtained using the new method becomes 25% of that using the conventional peak detection method.

Short-Time Fourier Transform-Brillouin Optical Time-Domain Reflectometry (STFT-BOTDR) implements STFT over the full frequency spectrum to measure the distributed temperature and strain along the optic fiber, providing new research advances in dynamic distributed sensing. The spatial and frequency resolution of the dynamic sensing are limited by the Signal to Noise Ratio (SNR) and the Time-Frequency (T-F) localization of the input pulse shape. T-F localization is fundamentally important for the communication system, which suppresses interchannel interference (ICI) and intersymbol interference (ISI) to improve the transmission quality in multicarrier modulation (MCM). This paper demonstrates that the T-F localized input pulse shape can enhance the SNR and the spatial and frequency resolution in STFT-BOTDR. Simulation and experiments of T-F localized different pulses shapes are conducted to compare the limitation of the system resolution. The result indicates that rectangular pulse should be selected to optimize the spatial resolution and Lorentzian pulse could be chosen to optimize the frequency resolution, while Gaussian shape pulse can be used in general applications for its balanced performance in both spatial and frequency resolution. Meanwhile, T-F localization is proved to be useful in the pulse shape selection for system resolution optimization.

The comorbidity of substance use disorder (SUD), depression, and PTSD is common among veterans. Prior research has shown that among veterans with SUD and depression, those with PTSD did not maintain cognitive-behavioral treatment gains as well as those without PTSD. Thus, the current study was designed to evaluate whether adding trauma-focused treatment following an initial group-based integrated cognitive behavioral treatment (ICBT) for SUD and depression improved treatment outcomes. Participants were 123 veterans (89% male) recruited from the VA San Diego Healthcare System. All participants received ICBT in twice weekly, group-delivered sessions for 12 weeks (Phase 1). Participants were then randomized to receive 12 sessions of individual follow-up sessions (Phase 2) utilizing either ICBT or cognitive processing therapy that was modified to integrate SUD treatment (CPT-M). Results indicated that PTSD and depression symptoms slightly improved at the end of Phase 1 group ICBT and further improved through Phase 2 individual treatment (except for participants without PTSD who received CPT-M), with treatment gains maintained one year later. Substance use significantly improved at the end of Phase 1 group ICBT and these improvements were maintained through Phase 2 and the one year follow-up. Participants in the trauma-focused Phase 2 treatment (CPT-M) exhibited similar levels of symptom reduction and maintenance of treatment gains as those in the non-trauma-focused Phase 2 treatment (ICBT). However, there was a slight advantage for Phase 2 CPT-M over Phase 2 ICBT with respect to heavy drinking outcomes for individuals with PTSD. Overall, the combination of group ICBT followed by either CPT-M or ICBT individual therapy appears to be effective for veterans with depression, SUD, and trauma history.