Netsu Bussei
Online ISSN : 1881-414X
Print ISSN : 0913-946X
ISSN-L : 0913-946X
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Showing 1-5 articles out of 5 articles from the selected issue
  • Masaaki Hashimoto, Yoshihiro Taguchi
    2020 Volume 34 Issue 4 Pages 109-116
    Published: 2020
    Released: March 05, 2021
    JOURNALS FREE ACCESS

    This paper presents a millimeter-stroke electrothermal kirigami MEMS actuator with low driving power for endoscopic applications. Kirigami, a traditional Japanese art of paper cutting and folding, is a promising approach for engineering out-of-plane film structures. Based on the concept of a thermal bimorph kirigami film being folded by the thermal expansion difference, the proposed MEMS actuator is electrothermally transformed into an out-of-plane step structure. Two types of kirigami actuators, multistep and single-step actuator, were successfully fabricated by MEMS processes. The single step actuator with 2 mm film diameter provided a 0.2 mm vertical displacement at 131 mW, and the multistep actuator with 4 mm film diameter achieved a larger 1.1 mm actuation at only 128 mW.

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  • Kazuya Hosono, Tsuyoshi Nishi, Hiromichi Ohta
    2020 Volume 34 Issue 4 Pages 117-128
    Published: 2020
    Released: March 05, 2021
    JOURNALS FREE ACCESS

    As a measuring method by flash method of the contact pressure dependence of interlayer thermal resistance of 2 layered sample, there is a method of sandwiching the sample with transparent materials. In this case, the interlayer thermal resistance analysis is performed assuming that the heating light is absorbed by the sample surface and the radiant heat flux is proportional to the sample rear surface temperature and the sample and the transparent materials are in a thermally insulated state. Actually, there is a thermal contact between the sample and the transparent materials, so the influence on the measurement due to this contact can be considered. To evaluate this effect, 2-layer model (the opaque sample/transparent material) is assumed and the radiant heat flux from the rear surface of 2-layer material was studied when the surface of the material was pulse-heated. When the optical thickness of the transparent layer is about 0.1 or less and the product of the ratio of the 1st layer characteristic time to the 2nd layer characteristic time and the ratio of the 2nd layer heat capacity to 1st layer heat capacity is 0.5 or less, it was confirmed that 1st layer thermal diffusivity can be obtained with an accuracy of about 5% by the half-time method. In addition, it seems that it is desirable to use data about 5 times the characteristic time of the sample, because it is affected by the transparent layer later in the measurement time.

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  • Kenta Watanabe, Hiroshi Kakiuchida
    2020 Volume 34 Issue 4 Pages 129-136
    Published: 2020
    Released: March 05, 2021
    JOURNALS FREE ACCESS

    We examined the influence of condensation on infrared radiation of windows and indoor thermal environments in winter when condensation forms. Two windows, which had high- and low-emissivity (-e) surfaces, were installed in practical-sized rooms. One was a single glazing with an emissivity of ≈0.9 and the other consisted of a low-e film (0.13 on catalogue) retrofitted on single glazing. We measured emissivity of dry and wet window surfaces, as a function of surface temperature. In the practical-sized rooms, we measured air, window-surface, and globe temperatures, and discuss the indoor thermal environment at different atmospheres. The condensation on the windows increased the surface temperature and decreased the globe temperature, whereas it maintained air temperature constant indoors. The variation in these temperatures was explained based on emissivity change due to condensation. We discussed the relationship of indoor comfort with installation of low-e films and occurrence of condensation, using standard effective temperature (SET*).

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  • Takahiro Ohmura, Kento Ishii, Taichi Tasaka, Akira Kondo, Makio Naito
    2020 Volume 34 Issue 4 Pages 137-146
    Published: 2020
    Released: March 05, 2021
    JOURNALS FREE ACCESS

    Thermal conductivity measurement is important for the development of high-performance insulation materials such as nanoparticle insulation materials or vacuum insulation ones. So far, we have developed a method which can measure the thermal conductivity of a board at non-uniform temperature gradient field where Fourier rules cannot be applied. Furthermore, the method was applied for 300 mm square specimen in the temperature ranging from 100℃ to 600℃. In this paper, we have proposed the measurement principle, conditions and equipment that can measure the thermal conductivity of a rectangular specimen of 150mm×100mm at the temperature ranging from 100℃ to 900℃. In addition, the dimensionless number for evaluating the measurement error was defined, and the measurement method for improving the accuracy was developed. The relationship between the size of the specimen and the measurement accuracy was also made clear. As a result, the thermal conductivities of the nanoparticles insulation material obtained by the authors agreed within ±10% for the values measured by periodic heat method.

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  • Shin-ichi Morita, Toshihiro Haniu, Takanobu Yamada, Kazunori Takai, Ya ...
    2020 Volume 34 Issue 4 Pages 147-153
    Published: 2020
    Released: March 05, 2021
    JOURNALS FREE ACCESS

    This study shows the evaluation results of the calorific value of biomass fuel and waste fuel. The calorific value is measured by using an adiabatic type calorimeter. In the case of farming in Japan, even in the case of farming with in-greenhouse cultivation, the amount of shipments is suppressed by the inability or delay of growth of agricultural crops in winter. Farmers can obtain a variety of biomass fuels and waste fuels from nearby locations and want to determine if these various fuels can be used in combustion heaters. However, there are few the calorific value data of these fuel, so that it is difficult to estimate the usage and storage amount. The lack of data hinders the widespread use and utilization of these unused resources. This paper presents the results of measuring the calorific value of coniferous, hardwood, charcoal, bamboo, livestock manure compost as biomass fuel, engine oil filters and separator paper waste for condensers as waste fuel, and provides practical data for fuel diversification.

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