A newly developed Raman collection scheme, a wide area illumination (WAI) scheme, was employed to demonstrate its utility for the analysis of petroleum products. For this purpose, the compositional analysis of simulated naphtha samples was attempted. The WAI scheme utilized a laser beam that illuminated a sample in a circular fashion with a diameter of 6 mm and a focal length of 250 mm. The reproducibility of the Raman measurement can be improved due to decreased sensitivity of the sample position as well as orientation with regard to the focal plane, as shown in a previous study. Near-infrared (NIR) spectroscopy, widely adopted in the field of petroleum refining, was also employed to compare with the prediction results obtained using the WAI scheme. Since the Raman spectral feature is more distinct and selective, the resulting calibration accuracy could be improved as long as reproducible Raman spectra could be collected. Overall prediction results using Raman spectroscopy were superior to those from NIR spectroscopy. The feasibility of the WAI scheme for reliable Raman analysis of petroleum products such as naphtha was demonstrated in this paper.
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http://dx.doi.org/10.1366/000370207781393253 | DOI Listing |
Anal Chim Acta
December 2024
Department of Chemistry and Research Institute for Convergence of Basic Science, Hanyang University, Seoul, 04763, Republic of Korea. Electronic address:
Background: Physical characteristics of packed samples, such as packing density, influence subsequent near-infrared (NIR) and Raman spectral features. This potential decrease in accuracy is a concerning issue in practical applications, such as the analysis of pharmaceutical tablets using vibrational spectroscopy. Thus, we compared the accuracy tolerances of both methods under varying packing densities.
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February 2025
Department of Chemistry and Research Institute for Convergence of Basic Science, Hanyang University, Seoul 04763, Republic of Korea. Electronic address:
Neural Netw
December 2024
Department of Engineering, University of Cambridge, Trumpington Street, Cambridge, CB2 1PZ, UK.
Switching dynamics are prevalent in real-world systems, arising from either intrinsic changes or responses to external influences, which can be appropriately modeled by switched systems. Control synthesis for switched systems, especially integrating safety constraints, is recognized as a significant and challenging topic. This study focuses on devising a learning-based control strategy for switched nonlinear systems operating under arbitrary switching law.
View Article and Find Full Text PDFMed Biol Eng Comput
January 2025
School of Information Science and Engineering, Yunnan University, Kunming, 650504, China.
Heart sound signals are vital for the machine-assisted detection of congenital heart disease. However, the performance of diagnostic results is limited by noise during heart sound acquisition. A limitation of existing noise reduction schemes is that the pathological components of the signal are weak, which have the potential to be filtered out with the noise.
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Division of Infectious Diseases, Department of Medicine, Queen Mary Hospital, The University of Hong Kong, Hong Kong Special Administrative Region, China. Electronic address:
Background: Remdesivir (Veklury, Gilead Sciences, Foster City, CA, USA) and nirmatrelvir-ritonavir (Paxlovid, Pfizer, New York, NY, USA) were reported to improve the outcome of patients with mild-to-moderate COVID-19 symptoms. Preclinical data suggest that nirmatrelvir-ritonavir might be more effective than remdesivir alone or in combination with nirmatrelvir-ritonavir for people at high risk of severe COVID-19. We aimed to assess the safety and effectiveness of combining remdesivir and nirmatrelvir-ritonavir compared with using each drug alone for adults hospitalised with COVID-19.
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