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Refining High‐Resolution Brillouin Optical Correlation‐Domain Reflectometry Using Polymer Fibers by Modeling Refractive Index Differences in Optical Paths
No full textHigh-spatial-resolution Brillouin optical correlation-domain reflectometry (BOCDR) in perfluorinated graded-index polymer optical fibers (PFGI-POFs) is gaining attention for structural health monitoring. A major challenge has been accurately predicting Rayleigh noise behavior, which constrains the modulation amplitude and spatial resolution. However, prior models did not consider differences in optical path lengths caused by the refractive indices of silica fibers (used in circulators) and PFGI-POFs. We refine the noise model to incorporate these differences. Experiments with varying fiber lengths show that the revised model more accurately predicts Rayleigh noise bandwidth, especially with longer circulator fibers. Errors of up to 120 MHz in the conventional model are reduced to within 25 MHz, showing the importance of proper optical path modeling in BOCDR
Driving conditions and safety analyses of vehicles moving on highway bridges under seismic excitations
No full textThe effects of seismic responses on driving comfort and safety of vehicles when moving on highway bridges are investigated in this study. The driving comfort and driver perceptibility were examined using ISO’s overall vibration total value (OVTV), while driver reaction was simulated using second-order predictable-correction (SOPC) model. A 3D-FE model of an existing highway interchange and vehicle-bridge-seismic interaction model were utilized to simulate seismic responses and their effects on moving vehicles under two levels (L1 and L2) site-specific ground motion. Influences of earthquake intensity, bridge shapes, and driving conditions were examined using five types of vehicles: light vehicle, SUV, small truck, bus, and large truck. Simulations reveal that driving comfort had surpassed an uncomfortable level under L1 earthquake and reached an extremely uncomfortable level for most types of vehicles under L2 earthquake. Effects of seismic responses on driving conditions were worse inn curved bridges compared to the straight bridge. Three scenarios of driver reaction effects on vehicle safety against rollover and sideslipping were simulated by examining risks and defining safety indices. The results showed deceleration action gave the most desirable outcome, followed by combination of deceleration and changing course, while changing course only resulted in the least favorable outcome
Defective NiO Nanoparticles Supported on Nb2O5 for Solid‐Catalyzed Markovnikov‐Selective Hydroboration of Styrenes
No full textMarkovnikov selective hydroboration of alkenes with an air- and moisture-stable diboron reagent is a more challenging reaction than the anti-Markovnikov selective one. We report that nickel oxide (NiO) supported on niobium pentoxide (Nb2O5) efficiently catalyzed the hydroboration of 4-tert-butylstyrene, affording a Markovnikov (branched) adduct with excellent selectivity. To the best of our knowledge, this is the first report of the Markovnikov-selective hydroboration of styrenes with a diboron reagent, bis(pinacolato)diboron, using a solid catalyst. NiO on Nb2O5 contains Ni3+, which is more catalytically active than Ni2+, as a major species in contrast to bulk NiO. However, the catalytic activity decreased upon recycling tests because the Ni species leached from NiO/Nb2O5. The catalytically active species were NiO on Nb2O5 and leached Ni species. To improve the reusability of the catalyst system, NiO/Nb2O5, ZnO was introduced as a redeposition site for the leached Ni species. Ultimately, the desired Markovnikov adduct was obtained in high yield and selectivity using NiO/Nb2O5 in the presence of ZnO (92% yield and 92% selectivity), and catalyst reusability was also improved
The Influence of Students’ Attitudes on Aspects of Mathematical Thinking: An Empirical Study Focusing on Sequences among High School and Undergraduate Students
Get PDFDevelopment and Evaluation of a Middle Leader Development Program Centered on School Administrative Roles
Get PDFExamination of Factors Promoting School-wide Instruction of Information Literacy in Elementary and Junior High Schools
Get PDF<Research Notes>Academic Scope of Research on Life Environment Studies: A Panoramic Analysis of Research Trends Outside Specialized Journals
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