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Spectral reflectance is an intrinsic characteristic of objects which is useful for solving a variety of computer vision problems. In this work, we present a novel system for spectral reflectance recovery with a high temporal resolution by exploiting the unique color-forming mechanism of DLP projectors. DLP projectors use color wheels to produce desired light. Since the color wheels consist of several color segments and rotate fast, a DLP projector can be used as a light source with spectrally distinct illuminations. And, the appearance of a scene under the projector's irradiation can be captured by a high-speed camera. Our system is built on easily available devices and capable of taking spectral measurements at 100Hz. Based on the measurements, spectral reflectance of the scene is recovered using a linear model approximation. We carefully evaluate the accuracy of our system and demonstrate its effectiveness by spectral relighting of dynamic scenes.

Spectral reflectance is an intrinsic characteristic of objects which is useful for solving a variety of computer vision problems. In this work, we present a novel system for spectral reflectance recovery with a high temporal resolution by exploiting the unique color-forming mechanism of DLP projectors. DLP projectors use color wheels to produce desired light. Since the color wheels consist of several color segments and rotate fast, a DLP projector can be used as a light source with spectrally distinct illuminations. And, the appearance of a scene under the projector's irradiation can be captured by a high-speed camera. Our system is built on easily available devices and capable of taking spectral measurements at 100Hz. Based on the measurements, spectral reflectance of the scene is recovered using a linear model approximation. We carefully evaluate the accuracy of our system and demonstrate its effectiveness by spectral relighting of dynamic scenes.

N-doped carbons (NCs) have excellent electrocatalytic performance in oxygen reduction reaction, particularly in alkaline conditions, showing great promise of replacing commercial Pt/C catalysts in fuel cells and metal−air batteries. However, NCs are vulnerable when biased at high potentials, which suffer from denitrogenation and carbon corrosion. Such material degradation drastically undermines the activity, yet its dynamic evolution in response to the applied potentials is challenging to examine experimentally. In this work, we used differential electrochemical mass spectroscopy coupled with an optimized cell and observed the dynamic behaviors of NCs under operando conditions in KOH electrolyte. The corrosion of carbon occurred at ca. 1.2 V vs RHE, which was >0.3 V below the measured onset potential of water oxidation. Denitrogenation proceeded in parallel with carbon corrosion, releasing both NO and NO 2 . Combined with the ex situ characterizations and density-functional theory calculations, we identified that the pyridinic nitrogen moieties were particularly in peril. Three denitrogenation pathways were also proposed. Finally, we demonstrated that transferring the oxidation reaction sites to the well-deposited metal hydroxide with optimized loading was effective in suppressing the N leaching. This work showed the dynamic evolution of NC under potential bias and might cast light on understanding and mitigating NC deactivation for practical applications.