A method of analyzing participant activity includes providing an identification unit to a participant, receiving signals from the identification unit, determining location of the participant based on the received signals, storing the location information and the associated timestamp and analyzing the stored information. Each sealing element has a body formed from an elastic material to have one or more impermeable bubbles filled with gas so that the sealing element has a volume which varies resiliently according to the change in volume of the bubble in response to externally applied pressure. In a first aspect of the present invention, the method and system enable secure and reliable peer-to-peer file sharing between two client nodes. The vehicle cleaning element can be configured for application to mitter cleaning elements and rotatable cleaning elements in automatic vehicle cleaning operations. Based on the tilt direction and the tilt angle, the attitude of the lenticular sheet is corrected in advance, preventing the lenticular sheet from skewing while stripe images are being recorded thereon.