Journal of the Japanese Society for Experimental Mechanics
Print ISSN : 1346-4930
ISSN-L : 1346-4930
Volume 21, Issue 1
Displaying 1-15 of 15 articles from this issue
Foreword
Review
  • Osamu TAJIMA
    Article type: research-article
    2021 Volume 21 Issue 1 Pages 4-11
    Published: April 10, 2021
    Released on J-STAGE: May 02, 2021
    JOURNAL FREE ACCESS

    ENE-FARM, a residential fuel cell, began general sales in 2009, and as of the end of September 2020, cumulative sales have reached 372,074 units. Stationary fuel cells are cogeneration systems that generate electricity and heat at the same time, with a total energy efficiency of over 80%. For this reason, it is becoming widespread as an energy device that contributes to CO2 reduction in the prevention of global warming. Ensuring safety is always a top priority. Reviewing regulations such as the Electricity Business Act and Fire Service Act and establishing a third-party certification system are the two wheels of a car to ensure the safety of residential fuel cell power generation systems. All ENE-FARM have obtained the certification mark. This paper focuses on this certification system and introduces the background to the establishment of the certification system and the outline of common certification criteria.

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  • Kenji AWASAKI
    Article type: research-article
    2021 Volume 21 Issue 1 Pages 12-15
    Published: April 10, 2021
    Released on J-STAGE: May 02, 2021
    JOURNAL FREE ACCESS

    When the aqueous solution is frozen, pure ice is first formed on the frozen interface and solutes and suspended solids are concentrated in the unfrozen part. We will explain the outline of the freeze concentration separation method that uses this phenomenon to be able to recover rare resources, and explain the usefulness of irradiating the frozen interface with ultrasonic waves as a mean to obtain a clean frozen part even if the freezing rate is increased. I introduced that among solutes, substances with a larger diffusion coefficient are more likely to be concentrated and separated.

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Original Papers
  • Toru SAWAI, Satoru MIZUNO, Hiroki IMAMURA
    Article type: research-article
    2021 Volume 21 Issue 1 Pages 16-22
    Published: April 10, 2021
    Released on J-STAGE: May 02, 2021
    JOURNAL FREE ACCESS

    It is expected that conventional petroleum-based plastic will be replaced with biomass-based plastic to solve the issues of the global environment. To provide the dimensional stability of biomass-based plastics, the torrefaction treatment is conducted to reform the hydrophile property of woody biomass. There are two objectives of the study. One is to investigate the effect of torrefaction on thermal softening properties of wood powder. The other is to clarify the optimum mass yield conditions which simultaneously satisfy both water resistance and bending strength of extruded wood molding. The following results are obtained: (1) As the mass yield decreases, the softening temperature increases, which is related to the thermal decomposition of hemicellulose contained in woody biomass. (2) The torrefied wood powder has the non-Newtonian flow property of pseudo-plastic fluid. The mass yield has a large effect on apparent viscosity especially at low temperature conditions. (3) The decrease in the mass yield improves the hydrophobic property, but reduces the bending strength of extruded wood molding. From the result of the trade-off relationship between hydrophobic property and bending strength against mass yield, it is found that the optimum mass yield is around 0.9.

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  • Daizo TAKAOKA, Yukinori TANAKA, Koji MORI, Yuki IIDA, Nanako IBATA
    Article type: research-article
    2021 Volume 21 Issue 1 Pages 23-29
    Published: April 10, 2021
    Released on J-STAGE: May 02, 2021
    JOURNAL FREE ACCESS

    In order to develop an efficient water purification method using microbial fuel cells (MFCs), we experimentally investigated not only the time history of the electrical output and the I-V characteristics of MFCs with external resistance of 100Ω and 1000Ω, but COD changes of the artificial waste water whose types were set to acetic and butyric acid. There was almost no electrical output at the beginning of the experiment. The MFCs, however, had the electrical output as the experiment progresses since there were microorganisms that generate electricity. In addition, the electrical output of 100Ω was higher than that of the external resistance of 1000Ω. At this time, there was a correlation between the value of the electric output and the rate of decrease of COD, and the correlation becomes stronger when the electric output was high. Finally, it was confirmed that the value of the external resistance that maximizes the electrical output changes according to the state of the MFC cell. From the above results, it has been shown that controlling the external resistance to maximize the electrical output may accelerate the rate of COD reduction.

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Original Papers
  • Motoki TERANO, Masahiko YOSHINO, Takayuki UENO
    Article type: research-article
    2021 Volume 21 Issue 1 Pages 30-34
    Published: April 10, 2021
    Released on J-STAGE: May 02, 2021
    JOURNAL FREE ACCESS

    Metal nanodot arrays have unique optical characteristics. And they are expected to find applications in biosensors and optical devices. The authors are proposing that simple and efficient manufacturing processes are introduced for metal nanodot arrays. These processes are based on the combination of thin metal film coatings deposited on substrates and thermal self-aggregation. In this paper, we aim to observe thermal self-aggregation process by using in-situ SEM observation technique with heating stage. And we also study influence of nano plastic forming on thermal selfaggregation process. As results, we showed the follows: (1) In the observation of thermal self-aggregation process of Au nanodot arrays, thin Au films, which deposited on a quartz glass substrate by using a spatter coater, was separated into many pieces of complicated island shapes. Separated Au with island shape was aggregated into round dot shape. (2) When thin Au film was grooved by nano plastic forming, separation of the film proceeded from the fabricated groove. And nano Au structures were aligned in a groove pattern. Nano plastic forming was effective for controlling the thermal self-aggregated shape of thin Au film.

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  • Tomohisa KOJIMA,, Takumi AKAMURA, Tomoaki TSUJI, Mitsuo NOTOMI, Hiroto ...
    Article type: research-article
    2021 Volume 21 Issue 1 Pages 35-40
    Published: April 10, 2021
    Released on J-STAGE: May 02, 2021
    JOURNAL FREE ACCESS

    Recently, numerous researches have been conducted with gel materials which are soft materials expecting it to be applied to biomimetic robots, soft actuators, and organ models for operation training. However, since the gel is very soft, it is difficult to measure and evaluate the deformation characteristics. This study is a part of the research project which is to develop an experimental system with a human head model that can simulate and measure the strain in the deep brain to clarify the mechanism of sports concussion. In this study, we propose a measuring technique for the strain inside a transparent gel by applying the particle image velocimetry and digital image correlation. Using the laser light sheet, the motion of the tracer particles which is mixed in the gel were visualized at an arbitrary cross-section. Then substituting the random pattern to the visualized particles in the digital image correlation, the strain distribution of the cross-section was obtained. The obtained strains were validated with engineering strain. Consequently, it was shown that the strain distribution in the gel could be accurately measured though it included some error in the vicinity of the edge of the measurement region.

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  • Takuya HARA, Motoharu FUJIGAKI, Yuya FUWA, Junki SUGIYAMA, Takuya MIYA ...
    Article type: research-article
    2021 Volume 21 Issue 1 Pages 41-48
    Published: April 10, 2021
    Released on J-STAGE: May 02, 2021
    JOURNAL FREE ACCESS

    A sampling moire method is applied to a displacement and rotation angle measurement. The accuracy of phase difference analysis using the sampling moire method is from 1/100 to 1/1000 of the grating pitches. 2D phase distributions of the 2D grating are also obtained with the sampling moire method. 2D phase difference before and after the deformation gives the displacement at the point and the 2D phase also gives the coordinates at the point because the grating pitch is known. Authors proposed an analysis method of a rotation angle from the 2D phase difference distribution and the 2D phase distribution. In this paper, a synchronous measurement system for laser displacement meter and camera was built. It was applied to the dynamic deformation measurement of a road bridge. The results were compared with the results of laser displacement meter. It was confirmed that laser displacement meter and camera measurement results were synchronized. It was confirmed that the time series measurement system can measure dynamic displacement and rotation angle of a road bridge.

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