Removing and installing oxygen sensors behind catalytic converter .
拆卸和安装催化转化器后面的氧传感器。
These high frequencies correspond to the rotation speeds of centrifuges ; america tightly controls the export of frequency converter drives able to operate at frequencies above 600 hz .
According to the patent filing , the data centers would be located 3 to 7 miles off-shore and would make use of the pelamis wave energy converter units that turn ocean surface waves into electricity .