Y. Nishimura, A. Gubarevich, Katsumi Yoshida, Koji Okamoto
{"title":"Comparison of SiC and graphite oxidation behavior under conditions of HTGR air ingress accident","authors":"Y. Nishimura, A. Gubarevich, Katsumi Yoshida, Koji Okamoto","doi":"10.1299/mel.22-00315","DOIUrl":"https://doi.org/10.1299/mel.22-00315","url":null,"abstract":"","PeriodicalId":180561,"journal":{"name":"Mechanical Engineering Letters","volume":"23 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"121227046","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
{"title":"Film sensor for triaxial contact stress measurements on the human body","authors":"Yuko Kudo, K. Sasagawa, K. Fujisaki","doi":"10.1299/mel.22-00309","DOIUrl":"https://doi.org/10.1299/mel.22-00309","url":null,"abstract":"","PeriodicalId":180561,"journal":{"name":"Mechanical Engineering Letters","volume":"25 4","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"131521284","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The accurate measurement of thin liquid films in various environments is essential for several industrial applications. In this regard, measurement procedures involving the use of optical fibers are preferred because such fibers are resistant to heat and pressure. Herein, we propose a high-accuracy method to measure liquid films with thicknesses of <100 μm (about fiber diameter) on the basis of the variation in the intensity distribution of the laser light emitted from the optical fiber; the thickness is measured by using the light reflected from the air– liquid interface (called the glare light in this study). First, instead of using light with a Gaussian distribution (characteristic of conventional graded-index fibers), we consider a stepped-index-type optical fiber with a step distribution. We model the distribution of the light emitted from the optical fiber and analyze the reflected light, i.e., glare light, via the ray-tracing method. We model three distributions: the Gaussian, point-like, and step distributions, and then we found that the step-distribution-based approach facilitates high-resolution measurements of liquid films with thicknesses less than optical fiber diameter. Moreover, the reflected light intensities for different film thicknesses closely agreed with the experimental results obtained using a steppedindex fiber. Remarkably, the intensity of the reflected light linearly decreases with the increase in the film thickness when using the step distribution. The numerical results quantitatively agreed with experiments; therefore, these results indicate the possibility of numerical calibration for liquid-film measurements with the use of the proposed step distribution model.
{"title":"Accurate thin-film measurement method based on a distribution of laser intensity emitted from optical fiber: Proposal of step light emitted model for ray-tracing simulation","authors":"K. Yamaguchi, T. Sanada, Y. Mizushima","doi":"10.1299/mel.20-00419","DOIUrl":"https://doi.org/10.1299/mel.20-00419","url":null,"abstract":"The accurate measurement of thin liquid films in various environments is essential for several industrial applications. In this regard, measurement procedures involving the use of optical fibers are preferred because such fibers are resistant to heat and pressure. Herein, we propose a high-accuracy method to measure liquid films with thicknesses of <100 μm (about fiber diameter) on the basis of the variation in the intensity distribution of the laser light emitted from the optical fiber; the thickness is measured by using the light reflected from the air– liquid interface (called the glare light in this study). First, instead of using light with a Gaussian distribution (characteristic of conventional graded-index fibers), we consider a stepped-index-type optical fiber with a step distribution. We model the distribution of the light emitted from the optical fiber and analyze the reflected light, i.e., glare light, via the ray-tracing method. We model three distributions: the Gaussian, point-like, and step distributions, and then we found that the step-distribution-based approach facilitates high-resolution measurements of liquid films with thicknesses less than optical fiber diameter. Moreover, the reflected light intensities for different film thicknesses closely agreed with the experimental results obtained using a steppedindex fiber. Remarkably, the intensity of the reflected light linearly decreases with the increase in the film thickness when using the step distribution. The numerical results quantitatively agreed with experiments; therefore, these results indicate the possibility of numerical calibration for liquid-film measurements with the use of the proposed step distribution model.","PeriodicalId":180561,"journal":{"name":"Mechanical Engineering Letters","volume":"4 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"130313308","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
In this paper, we propose a new visualization method using self-organizing map (SOM) for computed results of fluid flow. Most of existing visualization method gives color depending on a certain physical value, such as pressure, vorticity, etc. However the choice of the physical value is arbitrary and sometimes loses important features. The present method firstly classifies all flow properties, i.e. pressure, velocity components and their spatial gradients at each grid point, by giving these properties as high order vectors to SOM. Then color is given to each grid point based on its location on the map so that the flow field be naturally painted including all flow properties. SOM is originally a two-dimensional (2D) map as the main purpose of SOM is to visualize high order vectors, but in the present study the map is not directly viewed and only used to determine color of each grid point. Hence we try to generate three-dimensional (3D) SOM to give three color components based on the map. Both 2D and 3D map results are shown to demonstrate the capability of the present method.
{"title":"Automatic flow visualization method using self-organizing map","authors":"M. Masuda, Y. Tamura","doi":"10.1299/mel.21-00336","DOIUrl":"https://doi.org/10.1299/mel.21-00336","url":null,"abstract":"In this paper, we propose a new visualization method using self-organizing map (SOM) for computed results of fluid flow. Most of existing visualization method gives color depending on a certain physical value, such as pressure, vorticity, etc. However the choice of the physical value is arbitrary and sometimes loses important features. The present method firstly classifies all flow properties, i.e. pressure, velocity components and their spatial gradients at each grid point, by giving these properties as high order vectors to SOM. Then color is given to each grid point based on its location on the map so that the flow field be naturally painted including all flow properties. SOM is originally a two-dimensional (2D) map as the main purpose of SOM is to visualize high order vectors, but in the present study the map is not directly viewed and only used to determine color of each grid point. Hence we try to generate three-dimensional (3D) SOM to give three color components based on the map. Both 2D and 3D map results are shown to demonstrate the capability of the present method.","PeriodicalId":180561,"journal":{"name":"Mechanical Engineering Letters","volume":"47 1","pages":"0"},"PeriodicalIF":0.0,"publicationDate":"1900-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"127283172","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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