Abstract: An actuator having good interlayer adhesion at a lamination interface, good conductivity of an electrode layer, and good smoothness of the electrode layer is provided. The actuator includes a plurality of elastomer layers and a plurality of electrode layers, and the elastomer layers and electrode layers are alternately laminated. The electrode layer contains carbon black, a content of the carbon black in the electrode layer is 10% by mass or more and 20% by mass or less, and a specific surface area of the carbon black is 380 g/m2 or more and 800 m2/g or less.

Abstract: In a method for determining a road surface condition, the speed of calculation is improved by applying an appropriate path limitation. To further improve the accuracy of determination, a time-series waveform of tire vibration detected by an acceleration sensor is windowed at time width T by a windowing means, and time-series waveforms of tire vibration in the respective time windows are extracted before feature vectors Xi of the respective time windows are calculated. Then kernel functions KA (X, Y) are calculated from the feature vectors Xi for the respective time windows and road surface feature vectors Yi, which are feature vectors for the respective time windows calculated from time-series waveforms of tire vibration having been determined in advance for distinctive road surface conditions.