The filter removes volatile, particulate and water-based contaminants from a fluid, such as lubricating oil, of a different density than the contaminants. The switching circuit utilizes the active switches as the switching devices, so that it can increase the switching speed, decrease the voltage drop and loss, being suitable to the low voltage circuits, and can judge or determine the master power supply and the back-up power supply, realizing the switching between the master and slave power supplies without interruption. Execution of the plurality of commands is scheduled in the environment so that the commands execute sequentially in programming order. In a specific embodiment, the device includes a buffer material disposed between the first electrode and the switching material. In addition, the connector clip can only be assembled in one way to prevent the connectors from being improperly positioned within the connector clip. The method uses the statistical characteristics of the received signal noise in controlling the antenna array in order to achieve directional reception in a wireless communication system and suppress co-channel interference.