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Search Results: 1 - 10 of 61337 matches for " Yu Sugawara "
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Improvement of Pitting Corrosion Resistance of Type 316L Stainless Steel by Potentiostatic Removal of Surface MnS Inclusions
Nobuyoshi Hara,Koichi Hirabayashi,Yu Sugawara,Izumi Muto
International Journal of Corrosion , 2012, DOI: 10.1155/2012/482730
Abstract: The beneficial effect of the removal of MnS inclusions on the pitting of stainless steels has been demonstrated in two ways. (1) High-purity Type 316L stainless steel with no inclusions was used as a specimen in the measurement of anodic polarization curves in 0.5?M NaCl and (2) commercial Type 316L stainless steel with MnS and slag-related inclusions was first polarized at different potentials for 30 min in 1?M Na2SO4 of pH 3 and then anodic polarization measurements were taken in 0.5?M NaCl. Pitting did not occur in the passive or transpassive region of the high-purity steel. The polarization treatment dissolved MnS and some oxide inclusions (CaO and SiO2) on the surface of the commercial steel. An increase in pitting potential of the commercial steel was noted after treatment at potentials above 0.2?V. At the same time, the number of current spikes due to metastable pits decreased significantly. These results are more likely due to the beneficial effect of removing MnS inclusions from the steel surface rather than the modification effect of the chemical composition of passive films on the surface. 1. Introduction Manganese sulfide (MnS) inclusions are known to act as the initiation sites of pitting corrosion on stainless steels [1–9], while the overall dissolution of the inclusions is not necessary for the formation of pit initiation sites [10–17]. It is therefore expected that the removal of surface MnS inclusions improves the pitting corrosion resistance of stainless steels. The aim of treating the surface of stainless steels with processes like nitric acid passivation (ASTM A380 and ASTM A967) is to form a stable Cr-enriched passive oxide film [18], which plays an important role in providing high corrosion resistance to stainless steels. Such surface treatment has an additional effect of dissolving and removing the MnS inclusions from the surface of stainless steels [19]. Therefore, the improvement of pitting corrosion resistance by passivation treatments can be attributed not only to the modification of the chemical composition of the passive films but also to the removal of MnS from the surface of stainless steels. However, these two effects cannot be distinguished from each other in practice. For the further development of passivation treatments of stainless steels which meet environmental regulations and human safety standards, it is important to understand the intrinsic mechanism of each effect provided by passivation treatments. The purpose of the present study is to examine solely the effect of removing MnS on the pitting corrosion
Sensory Evaluation Spectrum Method as a Descriptive Sensory Analysis  [PDF]
Yoshie Yamagata, Yoshiaki Sugawara
Psychology (PSYCH) , 2014, DOI: 10.4236/psych.2014.514170
Abstract: Sensory evaluation is used to measure consciousness, and primarily developed in experimental and mathematical psychology. Sensory experiences can be reported using verbal (semantic) methods. This paper presents an overview of our semantic research achievements over the past decade, focusing on methodological attempts for substantiating the measure as a descriptive sensory analysis. Two types of studies that deserve particular attention are detailed: 1) evaluation of the efficacy of photo catalytic elimination of stains or bio-aerosols in air using TiO2 and photo catalytic deodorizing properties of a TiO2-type deodorizer; and 2) evaluation of the differential discrimination of perceived odor quality for a given aroma while inhaling the fragrances of essential oils. Both studies are based on semantic responses of participants. The perceived sensory attributes in the participants can be represented by a sensory spectrum: a bar graph whereby the mean of the impressions is plotted against the setting semantic impression descriptors. In the former study, we provide a background on the sensory evaluation spectrum method and discuss its implementation as a measure of descriptive sensory analysis. The latter study additionally demonstrates how statistical defects were overcome when spectra were not statistically significant.
Preparation and Optical Patterning of Organic-Inorganic Hybrid Color-Filter Films Using Latent Pigments by Utilizing Photo-Acid-Generator and Microwave Irradiation  [PDF]
T. Ohishi, S. Sugawara
Materials Sciences and Applications (MSA) , 2014, DOI: 10.4236/msa.2014.514111
Abstract: Preparation and photo-patterning characteristics of organic-inorganic hybrid thin film containing latent pigment by using photo-acid-generator (PAG) and microwave irradiation have been investigated. The acrylic thin film modified with methoxysilane containing PAG was formed on a glass substrate and irradiated with ultraviolet rays to promote sol-gel reaction by catalytic action of acid which was generated from PAG. And then the film was hardened with microwave irradiation, yielding organic-inorganic hybrid polymer film having hardness, highly transparency and strong adhesion with a glass substrate. Since this reaction only occurred in the optically (UV) irradiated regions, by exploiting the difference between the adhesivenesses of these regions photo-irradiated through photomask with a glass substrate, it was possible to form a patterned film with pitch of 100 to 50 μm by a simple lift-off method. A pigment-containing film using latent pigments (with subtractive three primary colors of coloring materials) and a patterned film were prepared, and it was possible to make these films multi-colored by varying the mixing ratio of the pigments. This multi-colored film-preparation method is effective for simply and efficiently forming a color-filter film by applying optical and microwave irradiation.
Suppression of Intramolecular Vibrational Energy Redistribution by Intense CW-Laser Fields
M. Sugawara
Advances in Physical Chemistry , 2011, DOI: 10.1155/2011/584082
Abstract: We present a quantum control scheme which realizes suppression of the intramolecular vibrational energy redistribution (IVR). In this scheme, we utilize effective decomposition brought by intense CW-laser fields, which enables to exclude the doorway state coupled to background manifolds. In doing so, we introduce a helper state and make it optically coupled with the doorway state through the intense CW-laser field. We have applied the present scheme to both the Bixon-Jortner model and the SCCl2 model system.
On the String Actions for the Generalized Two-dimensional Yang-Mills Theories
Yuji Sugawara
Physics , 1996, DOI: 10.1142/S0217732396001661
Abstract: We study the structures of partition functions of the large $N$ generalized two-dimensional Yang-Mills theories ($gYM_2$) by recasting the higher Casimirs. We clarify the appropriate interpretations of them and try to extend the Cordes-Moore-Ramgoolam's topological string model describing the ordinary $YM_2$ \cite{CMR} to those describing $gYM_2$. We present the expressions of the appropriate operators to reproduce the higher Casimir terms in $gYM_2$. The concept of ''deformed gravitational descendants'' will be introduced for this purpose.
Theory of Membrane in Heegaard Diagram Expansion
Hirotaka Sugawara
Physics , 2003,
Abstract: The vacuum amplitude of the closed membrane theory is investigated using the fact that any three-dimensional manifold has the corresponding Heegaard diagram (splitting) although it is not unique. We concentrate on the topological aspect with the geometry considered only perturbatively. In the simplest case where the action describes the free fields we find that the genus one amplitudes (lens space) are obtained from the S3 amplitude by merely renormalizing the membrane tension. The amplitudes corresponding to the Heegaard diagram of genus two or higher can be calculated as the Coulomb amplitudes with arbitrary charge distributed on a knot or a link which corresponds to the set of branch points of a given regular or an irregular covering space. We also discuss the case of membrane instanton.
F and M Theories as Gauge Theories of Area Preserving Algebra
Hirotaka Sugawara
Physics , 1997,
Abstract: F theory and M theory are formulated as gauge theories of area preserving diffeomorphism algebra. Our M theory is shown to be 1-brane formulation rather than 0-brane formulation of M theory of Banks, Fischler, Shenker and Susskind and the F theory is shown to be 1-brane formulation rather than -1-brane formulation of type IIB matrix theory of Ishibashi, Kawai, Kitazawa and Tsuchiya.
Thermal Partition Function of Superstring on Compactified PP-Wave
Yuji Sugawara
Physics , 2003, DOI: 10.1016/S0550-3213(03)00347-X
Abstract: We study the thermal partition function of superstring on the pp-wave background with the circle compactification along a transverse direction. We calculate it in the two ways: the operator formalism and the path-integral calculation. The former gives the finite result with no subtlety of the Wick rotation, which only contains the contributions of physical states. On the other hand, the latter yields the manifestly modular invariant expression, even though we only have the winding modes along the transverse circle (no Kaluza-Klein excitations). We also check the equivalence of these two analyses. The DLCQ approach makes the path-integration quite easy. Remarkably, we find that the contributions from the transverse winding sectors disappear in the non-DLCQ limit, while they indeed contribute in the DLCQ model, depending non-trivially on the longitudinal quantum numbers.
Topological String on AdS_3 x N
Yuji Sugawara
Physics , 1999, DOI: 10.1016/S0550-3213(00)00075-4
Abstract: We study the topologically twisted string theory on the general back-ground $AdS_3\times {\cal N}$ which is compatible with the world-sheet N=2 superconformal symmetry and is extensively discussed in the recent works (hep-th/9904024, hep-th/9904040). After summarizing the algebraic structure of the world-sheet topological theory, we show that the space-time (boundary) conformal theory should be also topological. We directly construct the space-time topological conformal algebra (twisted N=2 superconformal algebra) from the degrees of freedom in the world-sheet topological theory. Firstly, we work on the world-sheet of the string propagating near boundary, in which we can safely make use of the Wakimoto free field representation. Secondly, we present a more rigid formulation of space-time topological conformal algebra which is still valid far from the boundary along the line of (hep-th/9903219). We also discuss about the relation between this space-time topological theory and the twisted version of the space-time N=2 superconformal field theory given in (hep-th/9904024, hep-th/9904040).
Thermal Amplitudes in DLCQ Superstrings on PP-Waves
Yuji Sugawara
Physics , 2002, DOI: 10.1016/S0550-3213(02)01030-1
Abstract: We calculate the thermal partition function of DLCQ superstring on the maximally supersymmetric pp-wave background, which is realized as the Penrose limit of orbifolded $AdS_5\times S^5$ and known to be dual to the $\cN=2$ ``large'' quiver gauge theory as shown by S. Mukhi, M. Rangamani and E. Verlinde, hep-th/0204147. Making use of the path-integral technique, we derive the manifestly modular invariant expression and show the equivalence with the free energy of second quantized free superstring on this background. The ``virtual strings'' wound around the temporal circle play essential roles for realizing the modular invariance and for a simple analysis on the Hagedorn temperature. We also calculate the thermal one-loop amplitudes of open strings under the various backgrounds of the supersymmetric time-like and Euclidean D-branes, and confirm the existence of correct open-closed string duality. Furthermore, we extend these thermodynamical analysis to the 6-dimensional DLCQ pp-waves with general RR and NSNS flux. These superstring vacua are similarly derived from the supersymmetric (half SUSY) and non-supersymmetric orbifolds of $AdS_3 \times S^3 \times M^4$ ($M^4 =T^4 $ or $K3$) by the appropriate Penrose limits, giving rise to the SUSY enhancement as in the case of orbifolded $AdS_5 \times S^5$.
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