A pet fountain includes a water reservoir, and a spout connected with a water discharging end of the water reservoir. An off-line authentication client pre-stores a plurality of pattern element sequences each adapted to form a presentation pattern, and a plurality of verification codes created by applying a one-time-password derivation rule to the respective presentation patterns and subjecting the obtained results to a one-way function algorism. The system comprises encoder logic at each source processor that operates to associate a unique segment identifier with each of the packet segments before they are transmitted. An insulating layer and an overlying metal layer extend from the surface of the epitaxial layer into the half-trench. The processing system is configured to determine path-losses between the apparatus and a plurality of wireless nodes, to group the plurality of wireless nodes into sets based on the determined path-losses, and to exchange data with at least one of the wireless nodes in one of the sets. The headlamp can be used in several beam modes using a conventional reflection mirror and a discharge tube.