Assessment of tooth mobility using mechanical parameters of an electromagnetic vibration device reproduced fine details of various simulated periodontal ligament conditions. Variation in the parameters resonant frequency, elastic modulus and coefficient of viscosity might be useful in evaluating changes of components in periodontal tissues.

SummarySteel tubular members of offshore frame structures can suffer from corrosion damages in marine environments. Paint coating is usually applied for tubular members in splash and tidal zones as a corrosion protection. A typical mode of corrosion experienced in those members is distributed pitting corrosions as a result of degradation of coating materials. On the other hand, tubular members in water and soil zones are generally protected by a cathodic protection without coating materials, and a general corrosion spreading all over the surface is a typical mode of corrosion. In order to evaluate the structural integrity and resulting failure risk of offshore frame structures with corrosion damages, it is important to investigate the residual strength of corroded steel tubular members. In the present study, compressive and bending strengths of steel tubular members with general or putting corrosion are examined. Surface roughness measurements are made for tubular members with general corrosions taken from the splash zone, and ultimate strengths under axial compression and pure bending are examined both experimentally and numerically. Pitting corrosions as a result of degradation of coating are modeled based on the existing related test results and ultimate strength is examined numerically. Based on the obtained results, the applicability of existing design formula for the evaluation of residual strength of corroded steel tubular members is examined.

The tidal and sea current turbines are one of potential utilization of renewable energies as well as offshore wind ones. However they possibly produce efficiently electricity because of high density of water to air and more steadiness of flow to winds, hydro turbine generation system is less employed than wind one. We are studying an application of Straight Wing Vertical Axis Hydro Turbine Generation Systems in the tidal current. This paper presents the results of hydraulic model test using 2-dimensional channel and field test.

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It is impossible to distinguish slip surface clay from tectonic fault gouge based on only geological observation of surface of a drilled core. Then, half cut drilled core specimens prepared based on the resin fixing method were used to observe the slip surface clay and fault gouges in high-quality drilled cores in the landslide located in the Chichibu Belt in the Shikoku Central Mountain Region. Borehole inclinometers have detected cumulative displacements in this landslide. The results revealed fine structures such as composite planar fabric and asymmetric structures in finely crushed parts around the slip surface. In parts presumed to be slip surface clay, normal-fault sense was confirmed by the fine structure. Whereas in parts outside the slip surface, reverse-fault sense was confirmed by the composite planar fabric. Normal-fault sense in slip surface clay and reverse-fault sense in the other parts is consistent with those senses expected from the mechanisms of formation of a slip surface and tectonic faults in accretionary prism. Therefore, observing the fine composite planar fabric of a half cut core to evaluate the shear sense will be an effective method to distinguish slip surface clay from a fault gouge, which was formerly difficult to do simply by visually examining a drilled core surface.