Abstract: In a multinode, wireless packet-hopping network, all nodes operate on a same frequency, by waiting for each other. If the frequency is subject to excessive out-of-network jamming, the building computer transmits a “time-bomb”, i.e. an instruction for all nodes to change to a different frequency at a fixed time.

Abstract: A vacuum cleaner is provided that is adapted to detect and display and/or avoid obstacles. In such vacuum cleaners the driving wheels and/or castor wheels that determine the direction of travel may be actively controlled to achieve, at the point in time of obstacle touch or obstacle sensing, a resultant velocity away from obstacles in the path of the cleaning apparatus.

Abstract: Tools for setting precious and semi-precious stones in metal, and methods for using such tools to set such stones quickly and to accomplish such setting in the absence of chisel marks in the finished products. A first tool includes a disc-shaped rotating grinding member that has a beveled cutting edge for trimming excess metal prior to making the setting. A second tool has a disc-shaped rotatable cutting member having a kerfed cutting edge that produces parallel channels in such metal to thereby define a linear bar means therebetween which bar is manipulated by a conventional tool to form beads that retain the stones within their respective settings. The inventive method contemplates the use of the beveled edge tool to form beveled reflective surfaces on opposite sides of the stone, and use of the kerfed-edge tool thereafter to form the bead-producing bars. An alternative method contemplates using the kerfed edge tool first, followed by the beveled edge tool.