Upper level protocol message transmitting method and apparatus are provided based on a new management message to be used in a portable Internet system. A reservoir is in fluid communication with the heat exchanger to receive the flow of cooled compressed refrigerant and a second sensor is coupled to the reservoir and is operable to generate a second signal indicative of a reservoir liquid level. The inverting amplifier circuit inverts and amplifies the output voltage of the amplifier circuit with the same gain as that of the non-inverting amplifier circuit and then applies the amplified voltage to a second terminal of the piezoelectric actuator through resistors. The decoys are used to identify malicious behavior in the network and in particular to identify attempt to communicate directly with decoys in contradiction to the created interconnection topology. The frequency domain vectors are compressive beamformed tor the each sub-array to generate a plurality of bearing estimates corresponding to the plurality of sub-arrays. In one embodiment, the copy engine is configured to compare version information in the command with stored version information.