Generalized neural network approach to eddy current inversion for real cracks

This paper proposes a generalization for the solutions of an inversion method developed by the authors. The method is based upon an artificial neural network that simulates mapping between eddy current signals and crack profiles. One of the biggest advantages of the approach is that it can deal with conductive cracks, which is necessary to reconstruct natural cracks. However, it has one significant disadvantage: the reliability of reconstructed profiles was unknown. This paper also proposes a novel parameter that provides an index for assessment of the crack profile and overcomes this disadvantage. After the parameter is validated by reconstruction of simulated cracks, it is applied to reconstruction of natural cracks that occurred in steam generator tubes of a pressurized water reactor. It is shown that the parameter is applicable to not only simulated cracks but also real (natural) ones.     

Eddy current data for characterizing less volumetric stress corrosion cracking in nonmagnetic materials

The authors gather eddy current signals due to artificial stress corrosion cracking so that the data may be available to other researchers. Three cracks are introduced into an austenitic stainless steel plate, eddy current measurements are performed, and then the plate is destroyed to observe the cross-sectional profiles of the cracks. The authors will offer the data, as well as the true profile of the stress corrosion cracking revealed by destructive tests, to anybody who are interested in utilizing it in their studies.     

Production of nonequilibrium plasma and MHD interaction in disk MHD channel

The production of nonequilibrium plasma and the fluid flow with the MHD interaction are examined experimentally with a shock‐tube driven disk channel with no loading electrodes. For low magnetic flux density and low seed fraction, where nonuniform and unsteady plasma is generated, the static pressure decreases monotonically in the radial direction, although the pressure increases in the entire region of the channel in comparison with the value under no MHD interaction. For magnetic flux density and seed fraction above some critical values, a fairly uniform plasma is produced. The static pressure, however, is found to increase abruptly in the channel and the total pressure is considerably reduced at the location, where the abrupt pressure increase occurs. These facts imply that steady and uniform plasma should be produced without locally constricted strong Lorentz force to improve the adiabatic efficiency of a disk MHD generator. © 2002 Scripta Technica, Electr Eng Jpn, 138(4): 42–49, 2002; DOI 10.1002/eej.1137     

Poster3D: a system for three-dimensional authoring and presentation in immersive virtual environments

We developed a simple system for three-dimensional (3D) authoring and presentation in immersive virtual reality environments. Our system enables a user to create and edit content both through direct manipulation using hand gestures in an immersive environment, and by using a 2D GUI on a PC desktop. The system also exploits various features of 3D information visualization to produce effective and interactive presentations. In a system trial, users found that the system enhanced their experience. The system helps users create 3D educational materials more easily and learn through the materials with greater interest and motivation. Noritaka Osawa received his B.S., M.S. and Ph.D. degrees in information science from the University of Tokyo in 1983, 1985, and 1988 respectively. After working for a software company and the University of Electro-communications, he has been at the National Institute of Multimedia Education since 1998. He has also been jointly appointed at the Graduate University for Advanced Studies since 2001. He now works for them as a Professor. His current research interests include human–computer interfaces using virtual reality technologies, information visualization, and system software. Sangtae Kim received B.A. degree in Visual Communication from YougIn University, Korea, in 1996, and M.A. and Ph.D. degrees in Design, from the University of Tsukuba, 2001, and 2004, respectively. He is currently an Assistant Professor of the institute of Art and Design, The University of Tsukuba, Ibaraki, Japan. His research interests include visual communication, dynamic information graphics, multimedia systems, 3DCG, and Web3D technology. He planned for the MDD (Multi-Dynamic Documentation) project in 2003. At present, he is involved in the development of Web3D contents (Interactive Anatomy system) that uses MDD technology.     

X-ray diffraction of multiwalled carbon nanotube under high pressure: Structural durability on static compression

The structural durability of multiwalled carbon nanotubes under hydrostatic and non-hydrostatic compression was examined by in situ X-ray powder diffraction at room temperature. No interlayer interaction such as sp³ hybridization that could lead to hexagonal diamond in graphite was observed under compression up to 52 GPa, even though the nanotubes were similar in compressibility to graphite. This result could be attributed to the nested structure, which makes the interlayer stacking of carbon atoms take on an irregular arrangement. Despite the history of non-hydrostatic compression, electron microscopic observation revealed that the structure remained nested tubular. This reversibility suggests the nanotubes have strong durability on non-hydrostatic compression under extreme pressures.     

Physical properties and tactile sensory perception of microtextured molded plastics

We developed molded plastic samples with microscale textured features, and investigated the relationship between the tactile sensory response and the physical properties of the surfaces. Samples with various pitch features, and features with various height protrusions were prepared. Changes in the tactile sensory perception of the surfaces were correlated with the magnitude of the fluctuation in the coefficients of friction that occurred as a fingerprint moved across the surface, caused by the intrusion of the features of the textured surface into the grooves of the fingerprint. This occurred when the pitch of the features on the textured surface approached that of the pattern of the fingerprint; the height of the features was not significant. A change in the tactile perception of the surfaces occurred when the pitch of the features at the surface was approximately 100 μm.     

Enhancement of catalytic activity of alumina by copper addition for selective reduction of nitrogen monoxide by ethene in oxidizing atmosphere

The catalytic activity of alumina for the title reaction has been found to be greatly improved by the loading of copper. The addition of copper resulted in lowering the active temperature region, the higher maximum activity, and the enhancement of the reaction rate. The maximum effect was observed at 0.3 wt% of the loading amount of copper. A similar enhancement was also confirmed on SiO₂-Al₂O₃.     

[{W(O)(O2)2(H2O)}2(μ‐O)]2–‐Catalyzed Epoxidation of Allylic Alcohols in Water with High Selectivity and Utilization of Hydrogen Peroxide

A dinuclear peroxotungstate, K₂[{W(O)(O₂)₂(H₂O)}₂(μ‐O)]⋅2 H₂O, exhibits high catalytic performance for the epoxidation of various allylic alcohols with only one equivalent of hydrogen peroxide at 305 K in water solvent. The effectiveness of this system is evidenced by high chemo‐, regio‐, and diastereoselectivity, and stereospecificity for the epoxidation of allylic alcohols. Furthermore, products/catalyst separation can be easily carried out by simple extraction and the catalyst recovered can be reused with the maintenance of the catalytic performance.