Accurate phase analysis of waveform as fringe patterns is essential for a wide range of scientific and engineering disciplines. The phase-shifting method is a powerful tool to analyze the phase information of fringe patterns. This paper presents the fundamental principle and applications of a newly developed spatiotemporal phase-shifting method (ST-PSM) for noncontact three-dimensional shape and laser interference measurement. Simulation results indicated that ST-PSM had strong tolerance to random noise and a self-neutralizing function to eliminate the periodical phase error due to the nonlinearity of detector, intensity saturation, vibration or phase-shifting error, and the fluctuation of amplitude intensities due to the instability of laser source in the phase-shifting interferometry. The effectiveness was demonstrated experimentally from a non-contact shape measurement in fringe projection profilometry under extreme underexposure recording conditions. Furthermore, the ST-PSM realizes a much more stable measurement of phase and phase gradient distributions than the PSM in a Michelson laser interferometer experiment. We believe this technique has a significant impact on a variety of research and scientific fields.

This article describes the know-how and the procedures for measuring displacements and strains using digital image correlation. The procedure for creating random pattern on specimen surface, not only ordinarily size pattern, but fine pattern for microscopic measurement and coarse pattern for infrastructure is described. The adjustment of optical system for imaging such as the F-number related to the resolution and the depth of field of optical system is shown. In addition, the impacts of the data processing parameter such as the subset size, the subset shape function, and the window size for obtaining strains on the measurement results are described. The accurate and precise measurement is expected by the measurement procedure described in this article.

This paper experimentally investigates the effect of the resolution of the optical system on the measurement results of digital image correlation. The resolution is varied by changing the aperture of the lens. The actual values of the displacement are estimated by measuring the rigid body rotation, and the bias and the variance in the measured value are estimated from the measurement results. The effect of the Gaussian pre-filtering and the defocus is also evaluated. Results show that the aperture value affects the image, and as a result, it affects the measurement result. From the results, it is found that the F-number of f/8 or f/11 is suitable for obtaining images. In addition, the application of the Gaussian pre-filtering should be careful because the variance is increased by applying this filer. Furthermore, the defocus should be avoided because the both bias and variance are increased by defocusing.

To measure the deformation by the digital image correlation (DIC) method using a low-resolution camera mounted on a drone, an image correction method was developed by using four-axis correction and super-resolution processing. In this study, a three-point bending test of a beam was captured by a camera, and the deformation distribution was measured by the DIC method. First, the image was corrected by the 4-axis correction process when the captured position of the camera moved, and the effect on the DIC analysis results was evaluated. In the corrected image, the difference in relative error was about 2% compared to the DIC result by using conventional DIC process. Next, the improvement of measurement accuracy by super-resolution was evaluated. It was found that the relative error was improved more than 20% by 4 times super-resolution. Using these methods, DIC analysis was performed with a lowresolution camera mounted on a drone in flight. It was possible to measure the deformation distribution, although the accuracy was lower than that of the conventional DIC method.

High peak power laser attracted attention to utilize in laser processes at hazardous environment, such as deep sea, space and radiation fields. Radiation resistance glasses are used for barrier window near the radiation generators in hospital, and there is the possibility that the radiation resistance glass can use as barrier window in laser cutting process at radiation fields. In this study, coloration and damage of radiation-resistant lead glasses by nanosecond pulse laser with visible wavelength are evaluated. Three kinds of radiation resistance glasses with different lead content: PbO-55 wt%, 71 wt% and PbO free glass are used. As a result, the transitional coloration and damage formation with phase differences had observed by nanosecond pulsed laser irradiation at peak power of 1 kW. Although high-lead concentration glass has lower thresholds for coloration in laser intensity, damage-formation thresholds for both PbO glasses were almost the same. On the other hand, no change was observed after laser-irradiation to PbO-free glass. In addition, photochemical and thermal reaction of PbO by nanosecond pulsed laser irradiation is considered from the result of intensity change at wave numbers 200-500 cm^-1 and 1000 cm^-1 in Raman spectrums.

A wind tunnel experiment was carried out to investigate the movement characteristics of bed sediment grains in turbulent river flows through the partial assistance of machine learning. For gravel-bed rivers, the turbulent processes of bed-load transport was obtained by grain tracking analyses for various flow velocities. Near the critical flow velocity, about 50 % of total sediment grains moved on a bed surface in low time-probabilities. Over the critical flow velocity, in contrast, almost all sediment grains moved on a bed surface, and then, their time-probability rapidly increased. In particular, the turbulence intensities of bed sediment grain movement velocity were non-homogeneous, because the Stokes number was large. The parameter R (= streamwise turbulence intensity / spanwise turbulence intensity) varied complicatedly with an increase in the normalized Shields number τ*/τ*_c, such as, (1) taking a maximum value (the critical flow : τ*/τ*_c = 1.0) and decreasing rapidly, (2) increasing mildly, and (3) converging to a constant value(= about 1.85).

Magatama type blade configuration, which has been exclusively designed for vertical axis wind turbine (VAWT), is improved by Genetic Algorithm (GA). New Magatama blade section configurations, which generate aerodynamic force in direction of rotor rotation, are searched by GA. In this GA, the aerodynamic force is obtained by numerical simulation. Power performances of the VAWT with the obtained new Magatama blades are tested by wind tunnel experiments. Results show the power output from the VAWT rotor with the new Magatama blades is improved. Flow structure around the new Magatama blades in the VAWT rotor and aerodynamic forces generated by the blades are investigated by unsteady numerical simulation. Results show the new blades successfully generate aerodynamic forces that direction is close to the direction of rotation in upwind and downwind zones.

The measurement of a road surface friction coefficient is significant to improve the advanced driver assistance system (ADAS). ADAS uses the information from wheel sensors, acceleration sensors, yaw rate sensors, etc. However, it is difficult to measure the road surface friction coefficients accurately with these sensors. Therefore, various studies focusing on tires that are the only part contact with the road for a car have been conducted to measure the road surface friction coefficients. However, tires are susceptible to degradation and require frequent replacement. Therefore, this study focuses on a wheel and proposes a method to measure road surface friction coefficient from strains induced in the surface of a wheel. First, we clarified the relationship between the strains on a wheel and the loads acting on the tire from the grounding surface by using an experimental apparatus capable of simulating slip running. Second, a simple method of measuring road surface friction coefficients was proposed using the obtained relationship and indicated the measurement accuracy of road surface friction coefficients at various ground plates.