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81.
Wataru Tanikawa Toshihiko Shimamoto 《International Journal of Rock Mechanics and Mining Sciences》2009,46(2):229-238
We measured intrinsic permeability of sedimentary rocks from the western foothills of Taiwan by using nitrogen gas and distilled water as pore fluids in effective-pressure cycling tests at room temperature. The observed difference in gas and water permeabilities was analyzed in view of the Klinkenberg effect. This effect is due to the slip flow of gases at pore walls, which enhances gas flow when pore sizes are very small. Our experimental results showed that (1) gas permeability was larger than water permeability by several times to one order of magnitude, (2) gas permeability increased with increasing pore pressure, and (3) water permeability increased slightly as the pore-pressure gradient across the specimen increased. Results (1) and (2) can be explained quantitatively by an empirical power law in relation to the Klinkenberg constant b that is applicable in low permeable range. This correlation enables us to estimate water permeability from gas permeability. The Klinkenberg effect is important when permeability is lower than 10?18 m2 and at low pore-pressure differentials, and correction for the effect is essential to estimate water permeability from gas permeability measurement data. A simplified Bingham flow model for water can partially explain the trend of result (3), although non-Darcy flow behavior or inertial forces of water–rock interaction are needed to account for the observed deviation from Darcy's law. 相似文献
82.
Toshihiko Ohnuki Yukihiko Satou Satoshi Utsunomiya 《Journal of Nuclear Science and Technology》2019,56(9-10):790-800
ABSTRACTFollowing identification of radioactive Cs microparticles (CsMPs) in aerosol samples from the Fukushima Daiichi Nuclear Power Plant (FDNPP), numerous reports on CsMPs have been published. This paper reviews recent progress in the measurement and characterization of CsMPs by advanced analytical techniques, including advanced transmission electron microscopy (TEM) and synchrotron X-ray analysis. These analyses revealed that the CsMPs contained Si, Fe, Zn, Cs, and minor quantities of U together with some fission products. Uranium in the CsMPs was identified as being in the form of uraninite and (U,Zr)O2. Detailed advanced TEM analysis has clarified some of the processes resulting in the alteration of constituents of the nuclear fuels and containment vessel materials during this severe accident. In addition, a detailed report on the elemental compositions and structures of the fuel debris fragments collected inside and outside of the primary containment vessel25 highlighted the fact that the fuel debris fragments contained nanoparticles with the U and Zr components having similar structures to that of the CsMPs. This similarity in structures has stimulated further research on the structure and elemental constituents, especially for U and Zr in the CsMPs, and has opened up new avenues for studying the chemical characteristics of the fuel debris. 相似文献
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85.
Furuta Ryosuke Ikehata Satoshi Yamaskai Toshihiko Aizawa Kiyoharu 《Multimedia Tools and Applications》2018,77(10):12469-12491
Multimedia Tools and Applications - Cost-volume filtering (CVF) is one of the most widely used techniques for solving general multi-labeling problems based on a Markov random field (MRF). However... 相似文献
86.
By using pulse surface reaction rate analysis (PSRA), the detailed structure of the intermediate hydrocarbon species was revealed by measuring the dynamic behavior of both CO and H2 produced from the CO2-CH4 reaction on supported Ni catalysts. It was found that the number of hydrogen atoms involved in the intermediate was different from one catalyst support to another: 2.7 for MgO, 2.5 for ZnO, 2.4 for Al2O3,1.9 for TiO2, and 1.0 for SiO2. 相似文献
87.
Ultrafiltration membranes of poly(acrylonitrile-co-sodium styrenesulfonate) [P(AN-co-SSS)] were prepared by casting the copolymer solution into water. The ultrafiltration rate of P(AN-co-SSS) membranes was controlled by adding poly(ethylene glycol) (PEG) of various molecular weights to the casting solution. The effect of the PEG addition on the membrane properties was examined. By using the P(AN-co-SSS) membranes, which possess various molecular weight cutoff (MWCO) properties, the permeation behaviors of dextran (D) and dextransulfate (DS) were compared. The P(AN-co-SSS) membranes markedly restricted the permeation of DS, owing to electrostatic barrier of the negatively charged groups in the membrane. The electrostatic sieve separation of DS and D, each having similar molecular size, with the membranes was also investigated. The membrane having negatively charged groups effectively rejected to DS with a high permselectivity. © 1994 John Wiley & Sons, Inc. 相似文献
88.
Akira Takaki Toshihiko Hasegawa Masataka Isogawa Ikuo Narisawa 《Polymer Engineering and Science》1994,34(8):680-690
The fracture mode of poly(vinyl chloride)/methyl methacrylate/butadiene/styrene (PVC/MBS) polymer blends can change from ductile to brittle in accordance with the changes in shape of the test specimen or test conditions. Therefore, the mechanisms of impact energy absorption and the main cause of stress whitening are complicated. The following results on PVC/MBS blends were obtained by carrying out fracture experiments at different test speeds and temperatures:
- (1) The ductile/brittle fracture mode of the PVC and PVC/MBS blends can be explained by σ (the craze initiation stress)/σy (the shear yield initiation stress), which depends on the strain rates and temperature.
- (2) The fracture behavior of the PVC/MBS blends can be classified into the following types from the standpoints of fracture mode and whitening degree: Fracture I: ductile fracture without whitening; Fracture II: ductile fracture with whitening; and Fracture III: brittle fracture without whitening.
- (3) The following concepts can be estimated from the measurements of yield stress, specific gravity and SEM, TEM and visual observations. In Fracture I, shear yield occurs mainly. In Fracture II, both shear yield and crazing occur. In Fracture III, deformation of the rubber and local crazing occur.
- (4) The main cause of stress whitening in PVC/MBS blends is light scattering by cavities in the rubber particles.
- (5) In Fracture II, at first, crazes with cavities in the rubber particles occur. Then, shear yield occurs. Finally, crazes are healed by the heat, and only the cavities in the rubber remain.
89.
Songlan Yang Zheng Ming Sun Hitoshi Hashimoto Toshihiko Abe 《Journal of the European Ceramic Society》2003,23(16):3147-3152
In this study, free 2Ti/2Si/3TiC powder mixture was heated at high temperatures in vacuum, in order to reveal the possibility for the synthesis of high Ti3SiC2 content powder. X-ray diffraction (XRD) and scanning electron microscopy (SEM) were used for the evaluation of phase identities and the morphology of the powder after different treatments. Results showed that almost single phase Ti3SiC2 powder (99.3 wt.%) can be synthesized by heat treatment with free 2Ti/2Si/3TiC powders in vacuum at 1210°C for about 3 h. The nucleation and growth of Ti3SiC2 within TiC particles was observed. The typical appearance of the formed Ti3SiC2 is equiaxed with particle size of 2–4 μm. Effects of temperature and heating time on the morphology and the particle sizes of the synthesized Ti3SiC2 powders are not obvious. 相似文献
90.
The cryogel catalyst of platinum on alumina was prepared from aluminum sec-butoxide and H2PtCl6 through the sol-gel technique and subsequent freeze drying. The cryogel catalyst showed higher thermal stability of platinum
than the corresponding xerogel or impregnation catalysts, which was ascribed to the more intimately developed platinum-alumina
interaction accompanied by the encapsulation of the metal into the alumina cryogel. It was also shown that platinum accessibility
was higher on the cryogel than on the xerogel despite the higher thermal stability of the metal on the formed than on the
latter. For the VOC combustion, the cryogel exhibited higher activity than the xerogel and impregnation catalysts. Also for
the methane combustion the cryogel showed higher activity, although it showed lower activity than the impregnation catalysts
above 600 °C. By the addition of ceria as an additive to the cryogel catalyst, the CH4 combustion activity was improved especially in the temperature region above 600 °C. 相似文献