This paper proposes active contour models that splitting the control points can extract precisely and effectively an apex part from the extraction region in images. The problem of active contour models is that the contour of a smooth shape is converged relatively correctly, but that of a corner such as an apex is hard to converge due to the characteristics of these models. To solve this problem, some technical methods using shape models were suggested. However, such methods were under the restrictions that the contour of a shape in the extraction region must be similar to a shape model and prior knowledge of an extraction object must be required. The technical method presented in this study is to detect a high stress point between the control points in the contour convergence process of active contour models and to split the corresponding control points. As a result, the degree of freedom of a split control point increases and the control points are located closer to each other at an apex part than a smooth shaped part in the extraction region, which allows an apex part to be extracted precisely and effectively from the whole extraction region in images. We applied this method to an artificial image, conducted its experimental evaluation and proved its effectiveness.

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When we consider viewing the surface of human skin, the skin gives us a sense of natural depth, while, in contrast, the surface of a plastic does not. It is sure that the feeling of natural depth from human skin does not come from binocular disparity, because we can easily sense the natural depth of the skin, even when using only one eye. In our research program, learning from the structure of human skin, we fabricated screens which consist of multilayers made of translucent sheets coated with TiO₂ nanoparticles. The feeling of natural depth from our screen can be considered to come from the multiply-observed images produced by phase differences due to the translucent multi layers and the reflection/diffusion differences of light depending on its wavelength. Our screen can be applied to a projection screen for events, since it is simple, energy free, and applicable to a large area.

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Self-healing materials have been developed for emergency response of aerospace frames in USA. A typical example is a microcapsule-based polymer material with excellent self-healing abilities for micro-cracks. Although many self-healing materials have been created, few of them were commercialized for their high costs. In Japan scratch self-healing paints for car bodies have been developed and put on the market by a car manufacturer. These successes pushed new product developments and commercialization of self-healing materials. In near future many and various self-healing materials will be required not only in industries but also in living space.

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In recent years, much attention has been directed toward self-healing or self-mending properties of polymeric materials, because these properties are closely related to efficient utilization of natural resources, energy-saving, overcoming of environmental problems, and safety. The self-healing processes are indispensable for the design and production of new materials. There are two ways for designing self-healing materials. One is an engineering approach and the other is a chemical approach. Engineering approach mainly focuses on mesoscopic scale, as represented by composite material with crack-healing mechanism in it. Chemical approach mainly focuses on microscopic scale, as represented by polymers carrying functional groups that form reversible covalent or non-covalent bonds. In this review, these two approaches are briefly introduced. Especially, our recent research about self-healing materials based on host-guest interaction is further illustrated in detail.

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Self-healing materials attract a lot of attention due to their ability to repair the internal and external damage, thereby extending the lifetime of the materials in numerous applications that we cannot repair easily. A system using dynamic covalent chemistry is useful to achieve self-healing in polymeric materials, because this system enables healing at the molecular level and an unlimited number of healing times.  To date, many kinds of exchange reactions of dynamic covalent bonds that are driven by heating, light irradiation, or adding catalyst have been utilized for the healing. In this paper, we review such self-healing polymeric materials based on dynamic covalent chemistry.

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In this paper, after reviewing the research on self-crack healing of ceramics, a mechanism of self-crack healing of ceramics containing silicon carbide (SiC) were introduced. Self-crack-healing phenomenon is mainly due to high-temperature oxidation reaction of SiC. Furthermore, depending on the conditions of temperature and stress during service, it was found that a surface crack can be healed completely during service. Next, the research on the improvement of rolling contact fatigue strength of ceramics by the combined use of shot peening and crack-healing was introduced. The development of materials having more excellent cracks healing ability is desired in the future. Through these, applications to high temperature structural ceramic member and sliding member or the like is expected to greatly advance.

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Research works on self-repairing/self-healing technologies for cracks in cement concrete are being actively conducted. They show wide variety of mechanisms proposed since there are lots of possibilities to modify at both material and system levels. Concrete is a structural composite made of cementitious powders, water, sand, gravel and chemical agent and it is combined with reinforcing steel-bar for structural member. As conditions of technologies applicable to concrete it is requested to be always effective during a very long service life time of structures and to be cheap enough as construction material. This paper briefly introduces their mechanisms and concepts with technical development steps. Additionally, a unique behavior of air bubble formation excluded from water passing in a crack is explained as one of mechanisms for self-sealing.

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