Methods and systems for a sitemap generating client for web crawlers are described. The power waveform may be periodic andor phase-controlled. The second guide has a first guide surface and a second guide surface disposed to contact the recessed portion and the ridge portion of the sheet, respectively. The mount assemblies have a power conversion module, which is connected to an electric generator. In the display method using photonic crystal characteristics when a plurality of particles having electric charges is dispersed in a solvent, an electric field is applied to control inter-particle distance. The folding knife includes a latching mechanism that holds the blade in a closed and latched position against the opening force of the spring.