Abstract: A media item to be provided to users of a platform is identified. The media item is associated with a media class of one or more media classes. An indication of the media item is provided as input to a machine learning model trained based on historical encoding data to predict, for a given media item, a set of encoder parameter settings that satisfy a performance criterion in view of a respective media class of the given media item. The historical encoding data includes a prior set of encoder parameter settings that satisfied the performance criterion with respect to a prior media item associated with the respective class. Encoder parameter settings that satisfy the performance criterion in view of the media class is determined based on an output of the model. The media item is caused to be encoded using the determined encoder parameter settings.

Abstract: A triboelectric nanogenerating device is configured for providing an electric power to an electronic device and the triboelectric nanogenerating device includes at least one scaly triboelectric membrane configured for providing the electric power to the electronic device by frictional electrification. The at least one scaly triboelectric membrane includes a keratin and a polyvinyl alcohol, the at least one scaly triboelectric membrane has a first triboelectric surface, and the first triboelectric surface of the at least one scaly triboelectric membrane includes a plurality of scaly layers. Each of the scaly layers is arranged in order and extends along an orienting direction. A distal end of each of the scaly layers has a plurality of saw-tooth structures.

Abstract: A float board includes a main board and plural subordinate boards both made of a floatable material. The main board has plural through holes of the same shape and size as the subordinate boards so that the subordinate boards may fit completely in the through holes of the main board. The subordinate boards have a wearing band bound on an upper surface for a user's feet to wear for walking on beach sand. The main board may be used to float on water, with or without the subordinate boards.