A cavity-containing layer having a plurality of cavities is formed on a growth substrate by carrying out in alternating fashion a plurality of cycles of a first and second growth steps of growing a group III nitride at growth rates different from each other. The ink set includes an ink composition containing resin particles and a pigment, and a process liquid containing an organic acidic compound including a compound represented by General Formula. Each of the traction drives are independently driven by a separate drive motor. A first heating coil and a second heating coil can extend between the screen and a first cone and a second cone, respectively. Analysis of the phase shifts yields time difference of arrival information amongst the receivers, which is further processed to determine the location of the transmitter.