Abstract: The present invention provides a method and apparatus for locating the position of a lightning strike free of topography-dependent error by calculating a ground point having a difference in propagation distance at receiving stations (R1, R2 and R3) in at least three different locations. The difference in horizontal distance that would result in arrival time differences at the receiving stations is calculated using the horizontal coordinates of the respective stations. The ground point is taken as the tentative lightning strike position (X). The tentative lightning strike position is then corrected to a lightning strike position obtained by evaluating the arrival time difference in terms of the creepage distances (Ls) following depressions and elevations in the ground surface. The depressions and elevations in the ground surface are smoothed to a spatial wavelength that is comparable to the wavelength of the lightning electromagnetic waves.

Abstract: It is an object of the present invention to provide a lightning strike position locating method, apparatus, system and program that are free of topography-dependent error.

Abstract: A gas sensor which can be used for measuring a low concentration repeatedly, which has a quick response and which can be used for a long time with high stability is provided. The gas sensor comprises a solid electrolyte, a detecting electrode provided in contact with one of the surfaces of the solid electrolyte and exposed to a gas to be detected, a counter electrode, provided in contact with the other surface of the solid electrolyte, and lead wires to place an electric voltage across both electrodes or to take out electric signals, wherein an inactive substance which is hard to form a reaction product with the gas to be detected is used as a material to constitute both electrodes.