Abstract: A process for producing a tape-like material uniformly containing highly pure single-walled or multi-walled carbon nanotubes and a tape-like material produced thereby; a high-performance field emission electrode including the tape-like material; and a process for producing the field emission electrode. The carbon nanotubes are synthesized by arc discharge, wherein an inert gas or inert gas-containing mixed gas is jetted onto a cathode having a carbon material from the inside of a hollow electrode (11) used as an anode, and simultaneously an arc is generated to form a path of arc discharge along a stream of the gas. At the same time, by relative movement of the electrodes, the cathode spot of the arc is moved on the cathode, and the synthesized carbon nanotubes are formed into a tape.

Abstract: A process for producing a tape-like material uniformly containing highly pure single-walled or multi-walled carbon nanotubes with a high density highly pure single-walled or multi-walled carbon nanotubes; a high-performance field emission electrode including the tape-like material; and a process for producing the field emission electrode. For synthesis of carbon nanotubes by arc discharge, an inert gas or inert gas-containing mixed gas is jetted onto a cathode (2) comprising a carbon material from the inside (11a) of a hollow electrode (11) used as an anode, and simultaneously an arc is generated to form a path of arc discharge along the stream of the gas. Consequently, the cathode spot is prevented from irregularly moving, and thus highly pure carbon nanotubes can be produced. At the same time, by relatively moving both electrodes so as to move the cathode spot of the arc (3) on cathode, the synthesized carbon nanotubes are formed into a tape.

Abstract: The weld seam tracking and the welding torch height are controlled, the waveform of the welding voltage or the welding current of the arc is detected, the waveform of the above-described welding voltage or welding current under an appropriate welding condition to a reference gap G.sub.ref is stored as a reference waveform, the area .vertline..DELTA.SG.vertline. of a deviation part of the detected waveform to the above-described reference waveform is obtained, .DELTA.SG is obtained by judging the positive and negative of .vertline..DELTA.SG.vertline., the relationship between the value of .DELTA.SG and the root gap G is experimentally determined in advance, and the root gap G is calculated from the value of .DELTA.SG.

Abstract: A lattice welding robot detects an X-axis slide position of X.sub.p by an arc sensor of a welding torch, compares the value of X.sub.p with a reference value of X.sub.0 by a comparator, calculates a differential value of the value of X.sub.p by a differentiator and computes a travel speed correction amount .DELTA.V from a difference between a comparator output value and a differentiator output value by a computing unit. The correction amount .DELTA.V is added to an initial speed of each of inside wheels and outside wheels of a welding carriage to control each of driving motors for the inside wheels and the outside wheels by an adding speed command V.sub.in and an adding speed command V.sub.out, respectively. Thereby, a rough guidance for the welding carriage to trace a weld line is performed.