Discharge precipitate's impact in Li-air battery: Comparison of experiment and model predictions

This paper presents a fundamental study on the precipitate formation/morphology and impact of discharge precipitates in Li-air batteries and compares the voltage loss with two Li-air battery models, namely a film-resistor model and surface coverage model. Toray carbon cloth is selected as cathode, which serves as large-porosity electrodes with an approximately planar reaction surface. Imaging analysis shows film formation of precipitates is observed in all the experiments. In addition, toroidal and aggregate morphologies are present under lower currents as well. Specially, toroidal or partially toroidal deposit is observed for 0.06 A/cm2. Aggregates, which consist of small particles with grain boundaries, are shown for 0.03 A/cm2. We found that the film-resistor model is unable to predict the discharge voltage behaviors under the two lower currents due to the presence of the deposit morphologies other than the film formation. The coverage model's prediction shows acceptable agreement with the experimental data because the model accounts for impacts of various morphologies of precipitates

Experimental and computational investigation of confined laser-induced breakdown spectroscopy

This paper presents an experimental and computational study on laser-induced breakdown spectroscopy (LIBS) for both unconfined flat surface and confined cavity cases. An integrated LIBS system is employed to acquire the shockwave and plasma plume images. The computational model consists of the mass, momentum, and energy conservation equations, which are necessary to describe shockwave behaviors. The numerical predictions are validated against shadowgraphic images in terms of shockwave expansion and reflection. The three-dimensional (3D) shockwave morphology and velocity fields are displayed and discussed

OAO/ISLE Near-IR Spectroscopy of IRAS Galaxies

We present the results of the near-infrared (IR) spectroscopy of nine IRAS galaxies (NGC 1266, NGC 1320, NGC 2633, NGC 2903, NGC 3034, Mrk 33, NGC 7331, NGC 7625, NGC 7714) with the ISLE imager and spectrograph mounted on the Okayama Astrophysical Observatory 1.88 m telescope. [Fe II] 1.257 um and Pa beta emission lines were observed for the whole sample while H2 2.121 um and Br gamma lines were additionally obtained for two sources, whose flux ratios are used as a diagnostic tool of dominant energy sources of the galaxies. We find that the nucleus of NGC 1266 is most likely a low ionization nuclear emission-line region (LINER), while NGC 2633 and NGC 2903 possibly harbor active galactic nuclei (AGNs). No AGN or LINER signal is found for other objects. In addition, we find the spectral features which is indicative of some unusual phenomena occurring in the galaxies, such as the large [Fe II] line widths compared to the local escape velocity in NGC 1266. The present work shows the potential ability of the ISLE to shed new light on the nature of infrared galaxies, either through a statistical survey of galaxies or an exploration of spectral features found in individual objects.Comment: Accepted for publication in PAS