Hironori Tohmyoh

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To precisely examine the electrical failure behavior of a metallic nanowire mesh induced by Joule heating (i.e., melting), a previously developed numerical method was modified with regard to the maximum temperature in the mesh and the electrical resistivity of the nanowire. A sample case of an Ag nanowire mesh under specific working conditions was analyzed(More)
To accomplish a high-resolution ultrasonic imaging without wetting a sample, the efficiency of the dry-contact ultrasonic transmission is discussed. In this study, a dry-contact interface is formed on a sample by inserting a thin film between water and a sample, and the pressure is working on the interface by evacuating the air between the film and the(More)
Compared to the usual water immersion case, more effective transmission and reception of high-frequency ultrasound through a thin, solid layer are reported. A theoretical model is presented to perform the signal amplification and the signal modulation toward the higher frequency components for getting the high-quality acoustic images without immersing the(More)
This paper reports on a technique to measure the acoustic properties of a thin polymer film utilizing the frequency dependence of the reflection coefficient of ultrasound reflected back from a system comprising a reflection plate, the film, and a material that covers the film. The frequency components of the echo reflected from the back of the plate, where(More)
We report on a hybrid microscopy technique that enables us to measure the acoustic properties of a thin polymer film together with an optical microscope image of the corresponding area. Linear low-density polyethylene films are heated to various temperatures and examined by the technique. Density of the film is increased by heating and its sound velocity is(More)
The potential of the water-immersion and dry-contact acoustic imaging techniques for detecting nanometer gaps embedded in silicon is studied. The sensitivity for detecting gaps of over 10 nm in height is governed only by the lateral resolution of the imaging and is independent of the height of the gap.
Usually ultrasonic techniques tend to evaluate the closed cracks as smaller than the actual size. In this paper, we describe two strategic techniques for accurately evaluating the closed cracks by means of ultrasound. First, we show the advanced technique utilizing the thermal stress induced by cooling a cracked part. It is shown that a small amount of(More)
This paper reports the potential drop technique as an imaging tool for the clear identification and sensitive evaluation of very small surface cracks. The distributions of d-c potential drop around the surface cracks are obtained by scanning the closely coupled probes potential drop sensor, and a methodology for evaluating a 3-D crack from the potential(More)
This paper reports on a small-scale bending method for human hair. The test sample, which is elliptical in cross-section, is fixed to a hollow steel needle using resin to form a cantilever. A loading probe is used to subject this to a lateral load, where the load is applied parallel to either the long or short axis of the elliptical cross-section. From(More)