Unique designs are associated with articles of personal use, such as hairbrushes, hand mirrors, jewelry and the like. A monitoring system for wirelessly monitoring the process equipment can include a number of wireless sensors disposed within a fluid or gas process stream for monitoring various aspects of the fluid or gas medium such as temperature or pressure. The power management unit is used to manage the power supply from the power source to the DPF. In certain aspects, the method further includes disposing the aerofoil structure such that the frequency of the clearance gap variation is equivalent to the frequency of the aerofoil structure vibration and permits a flow through the clearance gap in which the flow tends to dampen the aerofoil structure vibrations.