A modulation control scheme for a series-connected dual active bridge DC to DC converter in a maximum power point tracking charge controller used in a photovoltaic system controls operation of the converter in a forward direction power flow mode to control charging of a battery bank with electricity produced by the photovoltaic array. In this case, the structure is an aircraft, and the two wireless stations are allocated on different aisles of the aircraft, respectively. The positive temperature coefficient characteristic is such that the impedance of the polymer increases with increasing temperature. The method further includes forming a transparent conducting layer atop the GaN multilayer structure, and adding a p-contact to the transparent conducting layer and a n-contact to the n-GaN layer. The system includes a radiation source rotatable about a patient, a radiation detector, and a computer coupled to the radiation source and the radiation detector wherein the computer is configured to receive data regarding a first energy spectrum of a scan of a head of the patient, receive data regarding a second energy spectrum of a scan of the head, and generate an image using the received data. Also, upon carvenosal injection therapy for erectile dysfunction, drugs for inducing erections can be easily injected into the space between the multiple slits or multiple pieces.