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2. Charge-changing interactions probing point-proton radii of nuclei

Author

Yamaki S., Kouno J., Nishimura D., Nagashima M., Takechi M., Sato K., Abe K., Abe Y., Fukuda M., Furuki H., Hachiuma I., Homma A., Ichihashi N., Ichikawa C., Inaba N., Ito T., Iwamoto K., Izumikawa T., Kamisho Y., Kikuchi N., Kinno S., Kitagawa A., Kojima T., Kuboki T., Mihara M., Miyazawa S., Momota S., Morita Y., Nagae D., Nakamura Y., Namihira K., Nishikiori R., Nishizuka I., Niwa T., Ogura M., Ohkuma Y., Ohtsubo T., Okada S., Ohno J., Ozawa A., Saito Y., Sakai T., Sato S., Sera D., Suzaki F., Suzuki S., Suzuki T., Taguchi M., Uenishi H., Wakabayashi M., Watanabe D., Yaguchi M., Yasumoto S., and Yamaguchi T.

Subjects
Physics, QC1-999
Abstract

The question of whether charge-changing interactions can be used to probe point-proton radii of nuclei remains unanswered. Charge-changing cross sections, σcc, were systematically investigated using stable and unstable nuclear beams of intermediateenergy. The ratios of the experimental σcc values to the calculated ones obtained from a phenomenological Glauber-type model analysis are found to be nearly constant in a broad range of Z/N for light neutron-rich nuclei. This enables the determination of density distributions, i.e., the radii of protons tightly bound in nuclei. To test the applicability of the present method to all nuclei in the nuclear chart, extensive measurements were performed for medium-mass nuclei ranging from Z = 18 to 32. The present study suggests the potential capability of a new experimental approach for exploring exotic nuclei.

Published
2014
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3. Measurements of interaction cross sections for 22–35Na isotopes

Author

Suzuki S., Takechi M., Ohtsubo T., Nishimura D., Fukuda M., Kuboki T., Nagashima M., Suzuki T., Yamaguchi T., Ozawa A., Ohishi H., Moriguchi T., Sumikama T., Geissel H., Aoi N., Chen Rui-Jiu, Fang De-Qing, Fukuda N., Fukuoka S., Furuki H., Inabe N., Ishibashi Y., Ito T., Izumikawa T., Kameda D., Kubo T., Lantz M., Lee C.S., Ma Yu-Gang, Mihara M., Momota S., Nagae D., Nishikiori R., Niwa T., Ohnishi T., Okumura K., Ogura T., Sakurai H., Sato K., Shimbara Y., Suzuki H., Takeda H., Takeuchi S., Tanaka K., Uenishi H., Winkler M., and Yanagisawa Y.

Subjects
Physics, QC1-999
Abstract

Interaction cross sections (σI) for 22−35Na isotopes from the stability line to the vicinity of the neutron drip line have been measured at around 240 MeV/nucleon. The σI for 33−35Na were measured for the first time. Enhancement in cross sections is clearly observed from the systematics for stable nuclei, for isotopes with large mass numbers. From the known values of the nuclear-deformation parameters β2 of 22−31Na, these enhancement can be mainly ascribed to the nuclear deformation. Large enhancement in heavier isotopes suggest that these nuclei are strongly deformed. The root-mean-square (RMS) nuclear matter radii were deduced from the σI by using Glauber-type calculation. Furthermore, a monotonic growth of the neutron-skin thickness has been deduced with increasing neutron number for Na isotopes.

Published
2014
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5. Influence of Mechanical Properties of Tube on Forming Limits and Deformation Characteristics in an Expansion Drawing Process.

Author

Zhang, S. L., Kuboki, T., Akiyama, M., and Kajikawa, S.

Subjects
*TUBES, *FINITE element method, *DEFORMATIONS (Mechanics)
Abstract

This paper describes an efficient method of manufacturing thin-walled metal tubes. The proposed method is an expansion drawing and it consists of two stages, flaring and drawing, during which high thickness reduction is achieved because the tube being processed is subjected to tensile stress in both the circumferential and axial directions. The optimal plug half-angle for various materials is investigated using a finite element analysis and experiments, revealing the plug shape with the highest expansion limit and the highest thickness reduction ratio. To investigate the deformation characteristics of different materials during the expansion drawing process, the strain in tubes formed using different materials was measured experimentally using a square grid on the outer surface of the tubes. In addition, a finite element analysis using hypothetical material properties revealed that the work-hardening exponent and friction coefficient affect tube deformation. The results of this work explain the influences of material properties on experimentally observed phenomena. Materials with a large work-hardening exponent are less prone to thinning during forming and have a greater forming limit. On the other hand, the larger the friction coefficient between the plug and the mother tube, the larger the deformation in the axial direction was, and then the thickness reduction increased due to biaxial tension. [ABSTRACT FROM AUTHOR]

Published
2024
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8. Hindered proton collectivity in 28S: Possible magic number at Z=16

Author

Togano, Y., Yamada, Y., Iwasa, N., Yamada, K., Motobayashi, T., Aoi, N., Baba, H., Bishop, S., Cai, X., Doornenbal, P., Fang, D., Furukawa, T., Ieki, K., Kawabata, T., Kanno, S., Kobayashi, N., Kondo, Y., Kuboki, T., Kume, N., Kurita, K., Kurokawa, M., Ma, Y. G., Matsuo, Y., Murakami, H., Matsushita, M., Nakamura, T., Okada, K., Ota, S., Satou, Y., Shimoura, S., Shioda, R., Tanaka, K. N., Takeuchi, S., Tian, W., Wang, H., Wang, J., and Yoneda, K.

Subjects
Nuclear Experiment
Abstract

The reduced transition probability B(E2;0 ->2+) for 28S was obtained experimentally using Coulomb excitation at 53 MeV/nucleon. The resultant B(E2) value 181(31) e2fm4 is smaller than the expectation based on empirical B(E2) systematics. The double ratio |M_n/M_p|/(N/Z) of the 0+ ->2+ transition in 28S was determined to be 1.9(2) by evaluating the M_n value from the known B(E2) value of the mirror nucleus 28Mg, showing the hindrance of proton collectivity relative to that of neutrons. These results indicate the emergence of the magic number Z=16 in the |T_z|=2 nucleus 28S., Comment: 10 pages, 3 figures. Published in Phys. Rev. Lett (http://link.aps.org/doi/10.1103/PhysRevLett.108.222501)

Published
2012
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9. Spectroscopy of 32Ne and the Island of Inversion

Author

Doornenbal, P., Scheit, H., Aoi, N., Takeuchi, S., Li, K., Takeshita, E., Wang, H., Baba, H., Deguchi, S., Fukuda, N., Geissel, H., Gernhäuser, R., Gibelin, J., Hachiuma, I., Hara, Y., Hinke, C., Inabe, N., Itahashi, K., Itoh, S., Kameda, D., Kanno, S., Kawada, Y., Kobayashi, N., Kondo, Y., Krücken, R., Kubo, T., Kuboki, T., Kusaka, K., Lantz, M., Michimasa, S., Motobayashi, T., Nakamura, T., Nakao, T., Namihira, K., Nishimura, S., Ohnishi, T., Ohtake, M., Orr, N. A., Otsu, H., Ozeki, K., Satou, Y., Shimoura, S., Sumikama, T., Takechi, M., Takeda, H., Tanaka, K. N., Tanaka, K., Togano, Y., Winkler, M., Yanagisawa, Y., Yoneda, K., Yoshida, A., Yoshida, K., and Sakurai, H.

Subjects
Nuclear Experiment
Abstract

We report on the first spectroscopic study of the N=22 nucleus 32Ne at the newly completed RIKEN Radioactive Ion Beam Factory. A single gamma-ray line with an energy of 722(9) keV was observed in both inelastic scattering of a 226 MeV/u 32Ne beam on a Carbon target and proton removal from 33Na at 245 MeV/u. This transition is assigned to the de-excitation of the first J^pi = 2+ state in 32Ne to the 0+ ground state. Interpreted through comparison with state-of-the-art shell model calculations, the low excitation energy demonstrates that the Island of Inversion extends to at least N=22 for the Ne isotopes., Comment: Accepted for publication in Phys. Rev. Lett. 11 pages, 3 figures

Published
2009
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17. Distinction between Proton-Neutron Density Distribution of Halo Nuclei at the Nuclear Surface via Reaction Cross Sections

Author

Nishimura, D., Fukuda, M., Takechi, M., Mihara, M., Ishikawa, D., Komurasaki, J., Matsuta, K., Matsumiya, R., Kuboki, T., Yoshitake, M., Suzuki, T., Yamaguchi, T., Nakajima, S., Saito, K., Miura, M., Hachiuma, I., Namihira, K., Ohtsubo, T., Shimbara, Y., Watanabe, R., Ohkuma, Y., Izumikawa, T., Tanaka, K., Suda, T., Ozawa, A., Yasuda, Y., Moriguchi, T., Momota, S., Fukuda, S., Sato, S., Kanazawa, M., and Kitagawa, A.

Published
2010
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19. Measurements of nuclear radii for neutron-rich Ne isotopes 28−32Ne

Author

Takechi, M., Ohtsubo, T., Kuboki, T., Fukuda, M., Nishimura, D., Suzuki, T., Yamaguchi, T., Ozawa, A., Moriguchi, T., Sumikama, T., Geissel, H., Aoi, N., Fukuda, N., Hachiuma, I., Inabe, N., Ishibashi, Y., Itoh, Y., Kameda, D., Kusaka, K., Lantz, M., Mihara, M., Miyashita, Y., Momota, S., Namihira, K., Ohishi, H., Ohkuma, Y., Ohnishi, T., Ohtake, M., Ogawa, K., Shimbara, Y., Suda, T., Suzuki, S., Takeda, H., Tanaka, K., Watanabe, R., Winkler, M., Yanagisawa, Y., Yasuda, Y., Yoshinaga, K., Yoshida, A., Yoshida, K., and Kubo, T.

Published
2010
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21. A comparison of colorimetric and visual methods for the assessment of masticatory performance with color-changeable chewing gum in older persons

Author

Kugimiya, Y, Watanabe, Y, Shirobe, M, Motohashi, Y, Motokawa, K, Edahiro, A, Ohara, Y, Ryu, M, Igarashi, K, Hoshino, D, Nakajima, J, Ueda, T, Taniguchi, Y, Ogawa, T, Maekawa, K, Tamaki, K, Kuboki, T, Kitamura, A, Shinkai, S, Hirano, H, Kugimiya, Y, Watanabe, Y, Shirobe, M, Motohashi, Y, Motokawa, K, Edahiro, A, Ohara, Y, Ryu, M, Igarashi, K, Hoshino, D, Nakajima, J, Ueda, T, Taniguchi, Y, Ogawa, T, Maekawa, K, Tamaki, K, Kuboki, T, Kitamura, A, Shinkai, S, and Hirano, H

Published
2021

24. Beta-NMR measurement of 58Cu in Si

Author

Mihara, M., Izumikawa, T., Ueno, H., Matsuta, K., Nishimura, D., Nagatomo, T., Moriguchi, T., Ito, Y., Nagae, D., Fukuda, M., Yoshimi, A., Yamada, K., Takechi, M., Ichikawa, Y., Momota, S., Hirayama, Y., Ohtsubo, T., Suzuki, S., Kubo, T., Namiki, Y., Ozawa, A., Ishibashi, Y., Oishi, H., Suzuki, K., Hachiuma, I., Namihira, K., Horikawa, D., Minamisono, T., Yamaguchi, T., Kuboki, T., Suzuki, T., Satoh, K., Kobayashi, Y., Asahi, K., Matsukawa, K., and Shirai, K.

Published
2010
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25. Effects of styrene-ethylene-butylene-styrene based additives on the mechanical properties of rice hull/polypropylene composites

Author

Kuboki, T., Lee, Y.H., Park, C.B., and Sain, M.

Subjects
PVH Corp., Clothing industry -- Mechanical properties, Polypropylene -- Mechanical properties, Composite materials industry -- Mechanical properties, Engineering and manufacturing industries, Science and technology, Mechanical properties
Abstract

The purpose of this study was to improve the mechanical properties (such as tensile, flexural, and impact strength) of rice hull/polypropylene composites, with the use of styrene-ethylene-butylene-styrene copolymer (SEBS) and maleated styrene-ethylene-butylene-styrene copolymer (SEBS-MA). The results suggested that both types of additives increased the impact strength of the composites significantly as their contents increased. However, only SEBS-MA improved the tensile and flexural strength of the composites. The results also indicated that the composites with SEBS-MA consistently showed better mechanical properties than the SEBS counterparts for all the contents. POLYM. ENG. SCI., 47:1148-1155, 2007. © 2007 Society of Plastics Engineers, INTRODUCTION Organic filler/polymer composites are widely used as a replacement for inorganic filler/polymer composites in various sectors such as the automotive, construction, and packaging industries. The advantages of organic filler/polymer [...]

Published
2007

36. Beta-NMR measurement of 58Cu in Si

Author

Mihara, M., primary, Izumikawa, T., additional, Ueno, H., additional, Matsuta, K., additional, Nishimura, D., additional, Nagatomo, T., additional, Moriguchi, T., additional, Ito, Y., additional, Nagae, D., additional, Fukuda, M., additional, Yoshimi, A., additional, Yamada, K., additional, Takechi, M., additional, Ichikawa, Y., additional, Momota, S., additional, Hirayama, Y., additional, Ohtsubo, T., additional, Suzuki, S., additional, Kubo, T., additional, Namiki, Y., additional, Ozawa, A., additional, Ishibashi, Y., additional, Oishi, H., additional, Suzuki, K., additional, Hachiuma, I., additional, Namihira, K., additional, Horikawa, D., additional, Minamisono, T., additional, Yamaguchi, T., additional, Kuboki, T., additional, Suzuki, T., additional, Satoh, K., additional, Kobayashi, Y., additional, Asahi, K., additional, Matsukawa, K., additional, and Shirai, K., additional

Published
2010
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47. Effects of extruder screw configurations on thermal properties of glass fiber‐reinforced polyamide 6 composites throughout the direct long‐fiber‐reinforced thermoplastics process

Author

Yang, M.Y., Kuboki, T., Wood, J., Ugresic, V., and Publica

Abstract

The direct long‐fiber‐reinforced thermoplastics (D‐LFT) process is a series of processes involving two twin‐screw extruders, a conveyer, and a compression molding machine. The second twin‐screw extruder is designed for mixing continuous fibers with polymer melt and plays an important role in the D‐LFT process. This study investigates effects of the screw configurations of the second extruder on thermal properties of glass fiber‐reinforced polyamide 6 (PA6) composites throughout the D‐LFT process. Two screw configurations, which generate low and high shear stress in composite melt (named the conveying and mixing screws, respectively), were used in the second twin‐screw extruder. Samples were taken from four different locations along the D‐LFT process and characterized using triple detection gel permeation chromatography (GPC), thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC). The results suggested that the molecular weight of the PA6 matrix increased in the later stages of the D‐LFT process (i.e., after the second extruder) by branching of PA6 molecules. In addition, the mixing screw decreased the molecular weight of the PA6 matrix more than the conveying screw. However, such a decrease in molecular weight had little influence on the thermal stability and crystallization behavior of the composites.

Published
2019

48. Analysis of spinner straightening utilizing the finite element method

Author

Kuboki, T., Kawasaki, K., Shohei Kajikawa, Matsumura, H., Ono, T., and Seimiya, H.

Subjects
Finite element method, Spinner, Straightener, Straightness, Warp, Moment, Curvature, Plasticity -- Mathematical models, Plasticitat, Elements finits, Mètode dels, Matemàtiques i estadística::Anàlisi numèrica::Mètodes en elements finits [Àrees temàtiques de la UPC], Plasticitat -- Models matemàtics
Abstract

This paper presents analysis methods utilizing the Finite Element Method for spinner straightening, and shows a guideline for optimum conditions. Two types of analysis methods were composed. Model [F-Expl], “full actual model with explicit scheme”, considers the rotational movement of dies as the actual process using the explicit scheme. Model [BndCr], “a model carrying out fundamental analysis on one cross section based on simple bending in the Finite Element Method (FEM)”, uses the FEM only for calculation of simple bending without rotation for obtaining the deformed bar shape. A series of experiments were conducted in an actual production line as well as the analyses by Model [F-Expl] and [BndCr]. The examination mainly focused upon the effect of straightening intensity by changing the die positions. The experimental and analytical results show some mechanism of straightening and a basic guideline for the optimum working condition.

Published
2019

49. Mechanical microstructure characterization of discontinuous-fiber reinforced composites by means of experimental-numerical micro tensile tests

Author

Schober, M., Dittman, K., Gumbsch, P., Kuboki, T., Hohe, J., and Publica

Subjects
mechanical characterization, micromechanics, numerical simulation, microstructure, fiber-matrix interfaces, micro-tensile tests, fiber reinforced composites
Abstract

The mechanical characteristics and especially the damage behavior of discontinuous‐fiber reinforced composites greatly depend on its constituents and also on its microstructural properties, namely the extent and distribution of fiber agglomerations, the fiber orientation distribution, and the fiber‐matrix interfaces. Several methods exist to individually analyze the different microstructural properties, such as µCT scanning to obtain the distribution of the fibers and their orientation and the Microbond test to obtain the interfacial characteristics. However, the interdependencies of the individual characteristics and the initiation of fracture with respect to the microstructure are still hard to analyze regarding a real composite structure. For this reason, the microscopic fra cture behavior of a glass fiber reinforced sheet molding compound (SMC) shall be investigated by means of a micro tensile test. Therefore, a specimen with a gauge length of approx. 1 mm, 0.3 mm width and 0.1 mm thickness is extracted from a composite plaque and put to an in‐situ observed tensile test. With a finite element model of each specimen, including the position and orientation of each fiber, the fiber‐matrix‐interface characteristics are extracted with a reverse‐engineering approach. The tests show a microstructure‐specific fracture behavior, which depends on the fiber dispersion, the fiber orientation, and the fiber‐matrix interfaces. The numerical simulations well agree with the physical experiments, making the obtained parameters suitable for further simulations of the investigated structure on a larger scale.

Published
2019

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