Based on the method FW-H acoustic model, how the parameters influence acoustic characteristics of the Hartmann acoustic generator were studied, which are resonator length, spacing between the jet and resonator tube, the diameter of resonator tube. The conclusions were induced just as below. The total sound pressure level (SPL) increases with the length of resonator tube, while the magnitude of fundamental frequency is reverse. And the total SPL oscillates with the increase of spacing between jet and resonator, and the oscillating distance period increases with diameter of resonator tube. And the Hartmann generator with larger diameter of resonator tube can produce a higher SPL. The results of the paper provide the instructing meaning for the application of the Hartmann acoustic generator.

Based on electromagnetic-wave penetration method, the electromagnetic wave attenuation abilities of six kinds of CNTs were studied in experiment at 12~18 GHz, whose diameter at 30 nm, 60 nm, 100 nm and length at 2 μm and 15 μm. Such results are concluded from the experiment. With the same diameter 30 nm, the absorption ability of CNTs with the length 15 μm is better than which with the length 2 μm; With the same diameter 60 nm, the absorption ability of CNTs with the length 2 μm is better than which with the length 15 μm; With the same diameter 100 nm, electromagnetic attenuation ability of CNTs with the length 15 μm is better than which with the length 2 μm. Electromagnetic attenuation ability order of CNTs with the same length is that Ф60 nm > Ф100 nm > Ф30 nm. On the absorption ability, the best is CNTs with Ф60 nm × 2 μm, and the worst is CNTs with Ф30 nm × 2 μm. At 12~18 GHz, the absorption orders of the six kinds of CNTs is that Ф60 nm × 2 μm > Ф 60 nm × 15 μm > Ф100 nm × 15 μm >Ф100 nm × 2 μm > Ф 30 nm × 15 μm > Ф 30 nm × 2 μm.