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Thermal Stress Measurement in Steel Plate Strengthened by CFRP and Aluminum Alloy Plates
T. Ishikawa,H. Kawano,T. Nagao,A. Kobayashi 한국강구조학회 2016 International Journal of Steel Structures Vol.16 No.4
In steel members strengthened by carbon-fiber reinforced polymer (CFRP) plates, the thermal stresses are introduced in the steel members, the CFRP plates and the adhesive layers when temperature changes because the linear thermal expansion coefficients of steel and CFRP are mismatched. As so far, the authors proposed a technique to reduce the thermal stress in steel members strengthened by CFRP plates, which involves bonding aluminum alloy plates with CFRP plates. In the proposed method, the thermal stress in steel member can be reduced so that there are negligible levels of stress in steel member when the cross sectional areas of CFRP and aluminum plates are designed to correspond to the coefficient of thermal expansion of steel, even though the thermal stresses are introduced in the CFRP and aluminum plates. In this study, to confirm the maintaining the thermal stress reduction in steel member by proposed method, thermal stress measurement in steel plate strengthened by CFRP and aluminum plates was carried out about 21 months. In this research, the thermal stress introduced in the steel plate strengthened by CFRP plates was also measured. Furthermore, to assume the thermal shear and normal (peel) stresses in adhesive layers, FE analysis with plane stress element was employed. As the result, it was shown the thermal stresses in steel plate with CFRP plate were able to calculate by using composite theory and measured temperature. Furthermore, in steel plate strengthened by CFRP and aluminum plates, the thermal stress introduced in steel plate was negligible-small through the all-season. It was found the thermal stresses in steel plate with CFRP plates as well as CFRP and aluminum plates were also estimated by using composite theory and measured temperature. In the steel plate strengthened by CFRP and aluminum plates, the thermal shear and normal stresses in adhesive layer glued to steel plate become smaller than that in the conventional CFRP bonded specimen. However, the shear stress in adhesive layers between CFRP and aluminum plates in proposed method was higher than the thermal stress in adhesive layers between CFRP plates in conventional method.
Applications of the Hauser-Feshbach Theory to Advanced Nuclear Sciences
T. Kawano,P. Talou,M. B. Chadwick,S. Holloway,P. Moller,T. Watanabe 한국물리학회 2011 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.59 No.23
Unique applications of the Hauser-Feshbach (HF) statistical theory in the nuclear science field, as well as the HF model code development at LANL are discussed. Our applied field in which HF is applicable is not necessarily limited to the particle-induced reactions. We combine the HF model with a theory of β-decay to calculate the β-delayed neutron and γ-ray emissions. These calculations can be performed for each β-decay precursor to estimate aggregate neutron and γ-ray energy release at fission. Another relatively new example at LANL is the ability to compute HF predictions with a Monte Carlo technique (MCHF), which gives all the correlated information.
Time Dependent Particle Emission From Fission Products
S. T. Holloway,Toshihiko Kawano,Peter Moller 한국물리학회 2011 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.59 No.23
Decay heating following nuclear fission is an important factor in the design of nuclear facilities; impacting a variety of aspects ranging from cooling requirements to shielding design. Calculations of decay heat, often assumed to be a simple product of activity and average decay product energy, are complicated by the so called ``pandemonium effect.'' Elucidated in the 1970?셲 this complication arises from beta-decays feeding high-energy nuclear levels; redistributing the available energy between betas and gammas. Increased interest in improving the theoretical predictions of decay probabilities has been, in part, motivated by the recent experimental effort utilizing the Total Absorption Gamma-ray Spectrometer (TAGS) to determine individual beta-decay transition probabilities to individual nuclear levels. Accurate predictions of decay heating require a detailed understanding of these transition probabilities, accurate representation of particle decays as well as reliable predictions of temporal inventories from fissioning systems. We will discuss a recent LANL effort to provide a time dependent study of particle emission from fission products through a combination of Quasiparticle Random Phase Approximation (QRPA) predictions of beta-decay probabilities, statistical Hauser-Feshbach techniques to obtain particle and gamma-ray emissions in statistical Hauser-Feshbach and the nuclear inventory code, CINDER.
Constraints on GUT 7-brane topology in F-theory
Hayashi, H.,Kawano, T.,Watari, T. North-Holland Pub. Co 2012 Physics letters: B Vol.708 No.1
We study the relation between phenomenological requirements and the topology of the surfaces that GUT 7-branes wrap in F-theory compactifications. In addition to the exotic matter free condition in the hypercharge flux scenario of SU(5)<SUB>GUT</SUB> breaking, we analyze a new condition that comes from a discrete symmetry aligning the contributions to low-energy Yukawa matrices from a number of codimension-three singularity points. We see that the exotic matter free condition excludes Hirzebruch surfaces (except F<SUB>0</SUB>) as the GUT surface, correcting an existing proof in the literature. We further find that the discrete symmetry for the alignment of the Yukawa matrices excludes del Pezzo surfaces and a rational elliptic surface as the GUT surface. Therefore, some GUT 7-brane surfaces are good for some phenomenological requirements, but sometimes not for others, and this aspect should be kept in mind in geometry search in F-theory compactifications.
Recent Advances in Nuclear Fission Theory: Pre- and Post-Scission Physics
P. Talou,T. Kawano,J. E. Lynn,P. Moller,O. Bouland,M. B. Chadwick 한국물리학회 2011 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.59 No.23
Recent advances in the modeling of the nuclear fission process for data evaluation purposes are reviewed. In particular, it is stressed that a more comprehensive approach to fission data is needed if predictive capability is to be achieved. The link between pre- and post-scission data is clarified and a path forward to evaluate those data in a consistent and comprehensive manner is presented. Two examples are given: (i) the modeling of fission cross-sections in the R-matrix formalism, for which results for Pu isotopes from A = 239 to 242 are presented; (ii) the modeling of prompt fissionneutrons in the Monte Carlo Hauser-Feshbach framework. Results for neutron-induced fission on ^(235)U are discussed.
J. L. Ullmann,A. J. Couture,A. L. Keksis,D. J. Vieira,,J. M. ODonnell,J. M. Wouters,M. Jandel,R. C. Haight,R. S. Rundberg,T. A. Bredeweg,T. Kawano,C. Y. Wu,J. A. Becker,A. Chyzh,B. Baramsai,G. E. Mitc 한국물리학회 2011 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.59 No.23
A careful new measurement of the ^(238)U(n,γ) cross section from 10 eV to 100 keV has been made using the DANCE detector at LANSCE. DANCE is a 4π calorimetric scintillator array consisting of 160 BaF^2 crystals. Measurements were made on a 48 mg/cm^2 depleted uranium target. The cross sections are in general in good agreement with previous measurements. The gamma-ray emission spectra, as a function of gamma multiplicity, were also measured and compared to model calculations.