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Search Results: 1 - 10 of 486 matches for " Yasuyuki Kaneno "
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The Corrosion Behavior of Ni3Al/Ni3V Two-Phase Intermetallic Compounds in Various Acidic Solutions
Gadang Priyotomo,Hideyuki Momono,Sanat Wagle,Kenji Okitsu,Akihiro Iwase,Yasuyuki Kaneno,Rokuro Nishimura,Takayuki Takasugi
International Journal of Corrosion , 2012, DOI: 10.1155/2012/626240
Abstract: The corrosion behavior of the Ni3Al/Ni3V two-phase intermetallic compounds with and without minor elements (Nb, Co, and Cr) to be composed of L12 phase (Ni3Al) and a mixed phase of L12 (Ni3Al) and D022 (Ni3V) has been investigated by using an immersion test in 0.5?kmol/m3 HCl, H2SO4, and HNO3 solutions. The surface morphology was observed before and after the immersion test by scanning electron microscope (SEM). The results were compared to those of the L12 single-phase Ni3(Si,Ti) and austenitic stainless steel type 304. In all acidic solutions, preferential dissolution of ( ) phase was found in Ni3Al/Ni3V, but no intergranular attack, whereas the attacks took place on Ni3(Si,Ti). The Ni3Al/Ni3V showed a higher corrosion resistance in HCl solution and a lower resistance in HNO3 solution than Ni3(Si,Ti) and type 304. The addition of the minor elements enhanced corrosion resistance in HNO3 solution, but not clearly in HCl and H2SO4 solutions. In HCl and H2SO4, their weight losses during the immersion test were almost the same. 1. Introduction Recently, Ni-Al-V intermetallic compounds with a two-phase microstructure of Ni3Al (L12) and Ni3V (D022) phases have been developed by Takasugi et al. [1–13] and are confirmed to exhibit a highly coherent interface between these constituent phases. They have superior mechanical properties (i.e., high creep rapture life, high hardness, low thermal expansion, and better thermal conductivity) and also have high tensile strength and fracture toughness over a broad range of temperature in comparison with those of Inconel 750, Inconel 718 and Hastelloy [1–13]. Therefore, the Ni3Al/Ni3V two-phase intermetallic compounds are a candidates as materials in land-based, marine-based, and aero-gas turbine industries (turbine blade), high strength nut and bolt, and high temperature bearing or high temperature tool [8, 9, 14]. However, many studies revealed that the intermetallic compounds containing aluminum are very susceptible to hydrogen embrittlement [15–18], where hydrogen embrittlement takes place with permeation of atomic hydrogen formed by corrosion reaction into the compounds. Hence, to suppress this environmental embrittlement a small amount of boron was added to these compounds. However, it was reported that the boron segregation at grain boundaries became the preferential dissolution site and led to the intergranular attack in the L12 single-phase Ni3(Si,Ti) [19]. Furthermore, Ni base intermetallic compounds such as single-phase Ni3(Si,Ti) have attractive properties for high-temperature structural material (e.g., high
Thermally Induced Nanocrystal Array of Poly(N-Vinylcarbazole) on Si-Wafer Substrate  [PDF]
Kazushi Yamada, Yasuyuki Tsuboi
Materials Sciences and Applications (MSA) , 2014, DOI: 10.4236/msa.2014.55032
Abstract:

Recently, nanostructures such as nanocrystals and nanoaggregates have attracted much attention in many quarters of materials, electronics, and biology to create higher-value-added functional nanoscale materials and films. In this research, the fabrication of nanoaggregates on ultrathin photoconductive films of poly(N-vinylcarbazole) (PVCz) by applying thermal treatment is demonstrated. The structure and size are discussed on the basis of the results of atomic force microscope images. As a result, after thermal treatment of these films above the glass transition temperature (Tg) of PVCz, different types of surface morphological changes were induced showing a dependence on the tacticity of PVCz. Radically polymerized PVCz(r) ultrathin film showed small aggregates with heights of ~8 nm on the film surface after thermal treatment, while cationically polymerized PVCz(c), which has higher isotactic diad fractions than PVCz(r), indicated similar aggregates on the film surface, although the number of aggregates was smaller than PVCz(r). It is considered that these different phenomena depend on the tacticity of PVCz and the interaction between PVCz molecules and the substrate surface.

Effect of Dehydrated Digested Effluent of Manure on Yield and Quality of Annual Forages and Soil Chemical Properties in Southern Kyushu, Japan  [PDF]
Sachiko Idota, Yasuyuki Ishii
Agricultural Sciences (AS) , 2014, DOI: 10.4236/as.2014.510090
Abstract:

Digested effluent of manure (DEM) produced by biogas-plants contains many macro- and micro-nutrients. In an experiment conducted in southern Kyushu (Japan), forage crops cultivated after receiving DEM and chemical fertilizers exhibited similar dry matter yields. From a logistical standpoint, however, DEM in liquid form is difficult to handle and apply due to the low concentration of nutrients. To overcome this shortcoming, we prepared dehydrated DEM (DDEM) by adding DEM to cattle manure without disturbing the manure fermentation process. The objective of this research was to evaluate the effect of DDEM on dry matter yield and nitrogen recovery rate in annual dual-cropping systems (summer crop of maize or sorghum and winter crop of Italian ryegrass) that are typical of the region and to compare these results to commercial cattle manure alone, in combination with chemical fertilizer (CM or CM + CF), or no fertilizer application (NF). In both cropping systems, the DDEM treatment produced similar dry matter yields (2.6 to 3.02 kg·m-2) and apparent nitrogen recovery rates (43% to 53%) as the CM + CF and CM treatments. This suggests that DDEM can potentially replace chemical fertilizers and commercial cattle manure in the region.

Performance Evaluation of Heat Exchangers in OTEC Using Ammonia/Water Mixture as Working Fluid  [PDF]
Takafumi Morisaki, Yasuyuki Ikegami
Open Journal of Fluid Dynamics (OJFD) , 2013, DOI: 10.4236/ojfd.2013.34037
Abstract: The ocean thermal energy conversion (OTEC) system is a promising solution to provide stable electricity supply. Although the available temperature difference in OTEC systems is small, an ammonia/water mixture as working fluid is expected to decrease irreversible losses in the heat exchangers and to improve system performance. However, in actual heat exchangers, an adequate temperature crossing does not occur in the condenser but in the evaporator. Therefore, clarification of this characteristic is important. To date, the logarithmic temperature difference (LMTD) method is used in performance evaluations of OTEC heat exchangers. This method is of limited use if physical properties of fluids vary. A generalized mean temperature difference (GMTD) method is introduced to perform this evaluation. As changes in fluid property values can be considered in the GMTD method, method dependencies on heat exchanger characteristics, effectiveness, and system characteristics can be studied. In particular, GMTD and LMTD using a pure substance were found to be almost equal. Mean temperature differences using mixtures as working fluid were higher in the evaporator, but lower in the condenser, from the GMTD method than from the LMTD method. For higher ammonia concentrations in ammonia/water mixtures, the mean temperature differences from both methods are different.
Sound Source Measurement of a Semi-Circular Cylinder in a Uniform Flow by Particle Image Velocimetry  [PDF]
Yasuyuki Oguma, Nobuyuki Fujisawa
Journal of Flow Control, Measurement & Visualization (JFCMV) , 2016, DOI: 10.4236/jfcmv.2016.44014
Abstract: In this paper, the measurement of an aerodynamic sound source for a semi-circular cylinder in a uniform flow is described using Particle Image Velocimetry (PIV). This experimental technique is based on vortex sound theory, where the time derivative of vorticity is evaluated with the aid of two sets of standard PIV systems. The experimental results indicate that the sound source for the semi-circular cylinder is located around the shear layer near the edge of the semi-circular cylinder. The sound source intensity and the area are reduced in the semi-circular cylinder compared with those of a circular cylinder. This result indicates that the aerodynamic sound of the semi- circular cylinder is smaller than that of the circular cylinder, which supports the microphone measurement result.
On the Weyl Transform with Symbol in the Gel'fand-Shilov Space and its Dual Space
OKA,YASUYUKI;
Cubo (Temuco) , 2010, DOI: 10.4067/S0719-06462010000300015
Abstract: in this paper, we claim two subjects. one is that the weyl transform with symbol in the gel'fand-shilov space l rr , r ≥ 1/2 , is a trace class operator. the other one is that the weyl transform with symbol in the generalized function (l rr )1, r ≥ 1/2 , is a continuous linear transformation from the gel'fand-shilov space l rr to (l rr )1. as r > 1, z. lozanov- crvenkovic and d. peri?ic have proved in [6] this result. our second claim includes their result.
Food Technologies for Delicious and Beautiful Polyphenols of Bitter Olives etc.
Yasuyuki Yamada
Journal of Food Technology , 2013, DOI: 10.3923/jftech.2011.141.142
Abstract: Polyphenols and nutrition are useful but frequently make the foods too bitter to eat e.g., fresh olives and oriental medicines, etc. To eat fresh olives must have been treated by sodium hydroxide or 5 months fermentation. Sodium hydroxide destroys all polyphenols and makes olive oil acidity high with the result of formation of sodium salts of fatty acids i.e., soap. However, there is no way to take the natural polyphenols tasty. This is the industrial situation in the world. The sodium hydroxide destroys olive structures and kills beneficial bacteria and rapidly decays and putrefies the olives. Contrarily the food technologies make olives strong and prevent oil leak which destroys alcohol quality when olives are mixed with alcohol. Researchers show that coagulations of olives etc. with calcium and carboxylation make bitters tasty and change the colors. When these are ingested into the stomach, gastric acid discoagulates and returns them to original bioactive substances with original pharmacologic activity. Because of the bitter as only one reason, olive industry produce a vast amount of industrial waste such as oil cake and sodium hydroxide to be abandoned into Mediterranean sea. These were all overcome by the food technologies. The researchers anticipate that these food technologies have vast potencies for current and potential food industry applications and for future developments.
Japanese companies’ inroads into Indonesia under Japanese military domination
Hikita Yasuyuki
Bijdragen tot de Taal-, Land- en Volkenkunde , 1996,
Abstract:
On the Weyl Transform with Symbol in the Gel'fand-Shilov Space and its Dual Space
YASUYUKI OKA
Cubo : A Mathematical Journal , 2010,
Abstract: In this paper, we claim two subjects. One is that the Weyl transform with symbol in the Gel'fand-Shilov space l r r , r ≥ 1/2 , is a trace class operator. The other one is that the Weyl transform with symbol in the generalized function (l r r )1, r ≥ 1/2 , is a continuous linear transformation from the Gel'fand-Shilov space l r r to (l r r )1. As r > 1, Z. Lozanov- Crvenkovic and D. Peri ic have proved in [6] this result. Our second claim includes their result. En este artículo afirmamos dos asuntos. El primero es que la transformada de Weyl con símbolo en el espacio de Gel'fand-Shilov l r r , r ≥ 1/2 , es un operador de clase trazo. El segundo asunto es que la transformación de Weyl con símbolo en las funciones generalizadas (l r r )1, r ≥ 1/2 , es una transformación lineal continua del espacio Gel’fand-Shilov l r r to (l r r )1 . Como r > 1, Z. Lozanov-Crvenkovic y D. Peri ic probaron en [6] este resultado. Nuestro resultado incluye su resultado.
Spectral zeta function and non-perturbative effects in ABJM Fermi-gas
Yasuyuki Hatsuda
Physics , 2015,
Abstract: The exact partition function in ABJM theory on three-sphere can be regarded as a canonical partition function of a non-interacting Fermi-gas with an unconventional Hamiltonian. All the information on the partition function is encoded in the discrete spectrum of this Hamiltonian. We explain how (quantum mechanical) non-perturbative corrections in the Fermi-gas system appear from a spectral consideration. Basic tools in our analysis are a Mellin-Barnes type integral representation and a spectral zeta function. From a consistency with known results, we conjecture that the spectral zeta function in the ABJM Fermi-gas has an infinite number of "non-perturbative" poles, which are invisible in the semi-classical expansion of the Planck constant. We observe that these poles indeed appear after summing up perturbative corrections. As a consequence, the perturbative resummation of the spectral zeta function causes non-perturbative corrections to the grand canonical partition function. We also present another example associated with a spectral problem in topological string theory. A conjectured non-perturbative free energy on the resolved conifold is successfully reproduced in this framework.
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