Research on LIBS online monitoring criteria for aircraft skin laser paint removal based on OPLS-DA.

Online monitoring technology plays a pivotal role in advancing the utilization of laser paint removal in aircraft maintenance and automation. Through the utilization of a high-frequency infrared pulse laser paint removal laser-induced breakdown spectroscopy (LIBS) online monitoring platform, this research conducted data collection encompassing 60 sets of LIBS spectra during the paint removal process. Classification and identification models were established employing principal component analysis (PCA), partial least squares discriminant analysis (PLS-DA), and orthogonal partial least squares discriminant analysis (OPLS-DA). These models served as the foundation for creating criteria and rules for the online LIBS monitoring of the controlled paint removal process for aircraft skin. In this research, 12 selected characteristic spectral lines were used to construct the OPLS-DA model, with a predictive root mean square error (RMSEP) of 0.2873. Both full spectrum and feature spectral line data achieved a predictive accuracy of 94.4%. The selection of feature spectral lines maintains predictive performance while significantly reducing the amount of input data. Consequently, this research offers a methodological reference for further advancements in online monitoring technology for laser paint removal in aircraft skin.

Bulk photovoltaic effect in ferroelectric nematic liquid crystals.

The bulk photovoltaic (BPV) effect in ferroelectric liquid crystals is of increasing scientific interest owing to its great potential for light-energy conversion. The ferroelectric nematic phase exhibits a huge spontaneous polarization that can be aligned to a preferred direction. In this Letter, we investigate the tensorial properties of the BPV effect in the planarly aligned ferroelectric nematic phase of the liquid crystalline material RM734. A steady-state short-circuit photocurrent of ~160 pA and an open-circuit photovoltage of ~50 mV were observed in a cell with a thickness of 5.5 µm under the illumination of ultraviolet light without any bias voltage. Based on the photocurrent measurements in different electrode configurations, the non-zero elements of the BPV tensor were obtained. The BPV effect is attributed to the combination of the spontaneous polarization and the asymmetric distribution of photoinduced charge carriers. This study not only provides an understanding of the bulk PV mechanism in soft ferroelectrics but also promises a wide range of unprecedented, to the best of our knowledge, benefits for light harvesting to engineer marketable photovoltaic devices.

Athermal panoramic annular lens design with a thermal analysis method.

An athermal 360∘×(30∘-100∘) and F/3.5 panoramic annular lens (PAL) system is designed. Through the optical mechanical thermal analysis results based on finite element analysis (FEA), it is expected that the system will have excellent performance under extreme temperature fluctuations. Simulation shows that the system is thermally insensitive in the temperature range from -40∘ C to 60°C, consistently providing great imaging capability with the modulation transfer function (MTF) value at 133 lp/mm greater than 0.3. The proposed design and analysis workflow contains an evaluation of thermal optical performance with a higher accuracy, thus having significance in future athermal optical design. We expect the designed PAL system to have a broad application prospect in the field of outdoor applications, including automatic navigation of vehicles and all-weather surveillance systems.

The Relationship Between Voice Parameters and Speech Intelligibility: A Scoping Review.

OBJECTIVE: To synthesize existing evidence of the relationship between voice parameters and speech intelligibility. METHODS: Following Preferred Reporting Items for Systematic Reviews and Meta-Analysis extension for Scoping Review (PRISMA-ScR) guidelines, 13 databases were searched and a manual search was conducted. A narrative synthesis of methodological quality, study characteristics, participant demographics, voice parameter categorization, and their relationship to speech intelligibility was conducted. A Grading of Recommendations Assessment, Development, and Evaluation (GRADE) assessment was also performed. RESULTS: A total of 5593 studies were retrieved, and 30 eligible studies were included in the final scoping review. The studies were given scores of 10-25 (average 16.93) out of 34 in the methodological quality assessment. Research that analyzed voice parameters related to speech intelligibility, encompassing perceptual, acoustic, and aerodynamic parameters, was included. Validated and nonvalidated perceptual voice assessments showed divergent results regarding the relationship between perceptual parameters and speech intelligibility. The relationship between acoustic parameters and speech intelligibility was found to be complex and the results were inconsistent. The limited research on aerodynamic parameters did not reach a consensus on their relationship with speech intelligibility. Studies in which listeners were not speech-language pathologists (SLPs) far outnumbered those with SLP listeners, and research conducted in English contexts significantly exceeded that in non-English contexts. The GRADE evaluation indicated that the quality of evidence varied from low to moderate. DISCUSSION: The results for the relationship between voice parameters and intelligibility showed significant heterogeneity. Future research should consider age-related voice changes and include diverse age groups. To enhance validity and comparability, it will be necessary to report effect sizes, tool validity, inter-rater reliability, and calibration procedures. Voice assessments should account for the validation status of tools because of their potential impact on the outcomes. The linguistic context may also influence the results.

Minimalist and High-Quality Panoramic Imaging With PSF-Aware Transformers.

High-quality panoramic images with a Field of View (FoV) of 360° are essential for contemporary panoramic computer vision tasks. However, conventional imaging systems come with sophisticated lens designs and heavy optical components. This disqualifies their usage in many mobile and wearable applications where thin and portable, minimalist imaging systems are desired. In this paper, we propose a Panoramic Computational Imaging Engine (PCIE) to achieve minimalist and high-quality panoramic imaging. With less than three spherical lenses, a Minimalist Panoramic Imaging Prototype (MPIP) is constructed based on the design of the Panoramic Annular Lens (PAL), but with low-quality imaging results due to aberrations and small image plane size. We propose two pipelines, i.e. Aberration Correction (AC) and Super-Resolution and Aberration Correction (SR&AC), to solve the image quality problems of MPIP, with imaging sensors of small and large pixel size, respectively. To leverage the prior information of the optical system, we propose a Point Spread Function (PSF) representation method to produce a PSF map as an additional modality. A PSF-aware Aberration-image Recovery Transformer (PART) is designed as a universal network for the two pipelines, in which the self-attention calculation and feature extraction are guided by the PSF map. We train PART on synthetic image pairs from simulation and put forward the PALHQ dataset to fill the gap of real-world high-quality PAL images for low-level vision. A comprehensive variety of experiments on synthetic and real-world benchmarks demonstrates the impressive imaging results of PCIE and the effectiveness of the PSF representation. We further deliver heuristic experimental findings for minimalist and high-quality panoramic imaging, in terms of the choices of prototype and pipeline, network architecture, training strategies, and dataset construction. Our dataset and code will be available at https://github.com/zju-jiangqi/PCIE-PART.