Mechanical Engineering Journal
Online ISSN : 2187-9745
Advance online publication
Showing 1-5 articles out of 5 articles from Advance online publication
  • Nami TAGAMI, Tamio IDA
    Article ID: 18-00294
    Published: 2019
    [Advance publication] Released: January 17, 2019

    Biocoke (BIC), made from all types of biomass is a solid fuel. Hemicellulose and lignin, essential chemical components of biomass, work as bonding agents of BIC solidification because they have softening and fluidity characteristics. Their characteristics make bonding structure inside of BIC during the formation process. Previous studies suggested that physical and mechanical characteristics of BIC are different if raw materials (kinds of biomass) are different even if forming conditions are the same. It was inferred that the reason was different of content rate of main components. Among various biomass, green tea has excellent formability. In this paper, we focus on the potential of green tea as a raw material of BIC. Firstly, we compared the fluidity of green tea with other biomass. Then, compressive strength tests of BIC made from green tea and other biomass were conducted. We used the trunk of conifers, the bark of conifers, bagasse, and rice straw other than green tea. The result of fluidity test indicated that green tea is easiest-to-flow biomass among the five biomasses. Moreover, the flow starting temperature was able to estimate from a content percentage and moisture content with ±30% accuracy by using our estimated equation. As results of compressive strength test, each BIC which was made from five biomasses have two peak points of compressive strength and apparent density. Green tea BIC made under all the test conditions has high apparent density 1.3-1.4g/cm3. On the other hand, green tea BIC has the lowest compressive strength among the five biomasses tested. We found out that the raw material which it is easy to fluidize by heating has low compressive strength from these results.

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  • Mariko TSURUTA-HAMAMURA, Manami AONO, Shin-ichiro IWAMIYA
    Article ID: 18-00303
    Published: 2019
    [Advance publication] Released: January 11, 2019

    Previous studies have reported gender differences in loudness perception. To clarify factors that affect loudness perception of men and women, so that differences in their processing of auditory stimuli might be revealed, we conducted four experiments using innovative experimental approaches. A rating experiment employed a wider range of sound stimuli and a greater number of categories on the verbal interval scale to elicit participants’ ratings of sounds at different sound pressure levels. As in previous studies, male participants tended to rate the same sounds as less loud than did females. An experiment with the method of adjustment measured the limits of sound pressure level perceived as soft or as loud, and replicated the gender effect: female participants selected lower levels than did males to represent both soft and loud sound categories. The final two experiments sought to measure perceived loudness on a (numeric) ratio scale rather than a (verbal) interval scale. Using the methods of magnitude estimation and magnitude production, these experiments did not produce the clear gender differences seen in the first two experiments. Differences in loudness judgments between males and females may actually reflect differences in the use of verbal expression rather than differences in perception of intensity.

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  • Xia ZHU, Keiji OGI
    Article ID: 18-00284
    Published: 2018
    [Advance publication] Released: December 27, 2018

    This paper presents the deformation behavior of SUS304 specimens during partial diameter-enlarged process in a rotation speed region higher than the rotation speed region of conventional diameter-enlarged processing methods. The deformation behavior of the specimen diameter during the process was measured at various axial-compressive forces, bending angles, and rotation speeds. Next, the effect of rotation speed on the deformation behavior was analyzed based on the concept of deformation-induced martensitic transformation and thermally-activated process associated with plastic deformation. The reduction of axial-compressive force and temperature rise during processing in high rotation speeds were investigated. Finally, the time constant of diameter-enlarged was obtained for the above parameters. By increasing the rotation speed, it is possible to shorten the processing time and perform processing at a low axial-compressive force with little temperature rise, which improves the processing efficiency. The time constant of the diameter-enlarged deformation process can be expressed as a function of the effective rotation parameter.

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  • Yoshiaki OKAMURA, Daisuke SUZUKI, Kazuki IKOMA, Takafumi NAGATOMO, Hir ...
    Article ID: 18-00446
    Published: 2018
    [Advance publication] Released: December 26, 2018

    Fretting wear is a surface damage caused by repeated slight relative slips between two contact surfaces. In railway applications, fretting wear can occur between the inner ring and the backing ring of an axle journal tapered roller bearing. The authors supposed that the fretting wear of the backing ring can be prevented by means of hard-film coatings if hard films can follow the deformation of the backing ring. A segment-structured diamond-like carbon (S-DLC) film has been proposed to solve this problem. In this work, the authors investigated the effect of S-DLC film on the fretting wear through rotation tests of full-scale railway axle bearings with the backing ring side face coated with S-DLC film or conventional continuous diamond-like carbon (C-DLC) film. As the result, the S-DLC film coated backing ring demonstrated less wear compared to the C-DLC film coated backing ring. In addition, the iron content of the grease in the bearing with the S-DLC film coated backing ring was lower than that of the grease in the bearing with the C-DLC film coated backing ring. It is conceivable that the relative sliding motion in the radial direction between them may be restrained by the latticed pattern of the S-DLC film being pressed into the inner ring large side face. It is concluded that the S-DLC film is effective in suppressing the fretting wear generated on the contact surfaces between them of the axle bearings.

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  • Fatma Yıldız ÇAVDAR, Agah UĞUZ
    Article ID: 18-00298
    Published: 2018
    [Advance publication] Released: December 24, 2018

    In this study, an experimental investigation of the electrospinning process has been conducted using two successive Taguchi experimental designs, namely L18 (35) and L9 (34) for the electrospinning setups with a rotating drum and a stationary plate, respectively. The processing parameters are; concentration of poly(vinyl alcohol) in aqueous solution, applied voltage, distance between the needle and the collector, flow rate of the polymer solution and the rotational speed of the collecting drum. The primary process setup is used to analyse the effects of the parameters to the diameter of nanofibers and its standard deviation (SD), through examinations of the range analysis and graphical interpretations. The secondary process set up is used to gather the data to verify the results and to compare the effects of the collecting methods on the process outputs. A short literature review of the publications on which parameter effects were analysed by statistical methods is also presented.

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