Research on seismic intensity zonation by use of the response intensity of historical earth－quakes───with the central part of Shanxi Province as an example

With the central part of Shanxi Province as an example, this paper studied seismic intensity zonation directly by use of the response intensity of historical earthquakes. From the result, some conclusions can be drawn as follows: ① For areas rich in data of historical earthquakes, the seismic intensity zonation map with probabilistic meanings can be compiled by use of the statistical features of the response intensity of sites; ② When determining the length of time for statistics, the completeness of response intensity data and the inhomogeneity of regional seismic activities should be fully considered; ③ By comparing the seismic intensity zonation result for recurrence interval of 500 years with the new Seismic Intensity Zonation Map of China (1990), it has been found that the two are roughly similar; though they are somewhat different for some localities, each has its own reasonableness.

Dependence of Nonlinear Optical Response of Anatase TiO2 on Shape and Excitation Intensity

Nonlinear optical （NLO） properties of anatase TiO2 with nanostructures of nanopaxticle （NP）, nanowire （NW） and annealed nanowire （NWA） are studied by open-aperture and closed-aperture Z-scan techniques with a fem- tosecond pulsed laser at wavelengths of 532 nm and 780 nm simultaneously. At 532 nm, when increasing excitation intensity, NLO absorption of TiO2 NPs transforms from saturable absorption to reverse-saturable absorption. However, NWs and NWAs exhibit the opposite change. At 780nm, all samples show reverse-saturable absorption, but have different sensitivities to excitation intensity. Due to the larger surface-to-volume ratio of NPs and less defects of NWAs by annealing, nonlinear optical absorption coet^icients follow the order NPs≥ NWs≥ NWAs. The results also show that these shape and annealing effects axe dominant at low excitation intensity, but do not exhibit at the high excitation intensity. The NLO refractive index of NPs shows a positive linear relationship with the excitation intensity, whereas NW and NWAs exhibit a negative linear relationship. The results could provide some foundational guidance to applications of anatase TiO2 in optoelectronic devices or other aspects.

Phase error correction for fringe projection profilometry by using constrained cubic spline

In fringe projection profilometry, the nonlinear intensity response caused by the γ effect of a digital projector results in periodic phase error and therefore measurement error. Previous error correction methods are largely based on the calibration of single γ value. However, in practice, it is difficult to accurately model the full range of the intensity response with a one-parameter γ function. In this paper, a compensated intensity response curve is generated and fitted with the constrained cubic spline. With the compensated curve, the full range of the nonlinear intensity response can be corrected and the periodic phase errors can be removed significantly. Experimental results on a flat board confirm the average root mean square （RMS） of the phase error which can be reduced to at least 0.0049 rad.