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排序方式: 共有670条查询结果,搜索用时 31 毫秒
661.
Tomoya Fujisawa Shigeru Hamada Norimitsu Koga Daisuke Sasaki Toshihiro Tsuchiyama Nobuo Nakada Kazuki Takashima Masaharu Ueda Hiroshi Noguchi 《International Journal of Fracture》2014,185(1-2):17-29
In this study, in order to define a fatigue crack initiation unit, the relationship between the fatigue crack initiation process and the crystal structure in the pearlitic steel used for railroad rails was examined and fatigue tests, focusing on crack initiation, were performed. The fracture surfaces were analyzed using a scanning electron microscope (SEM) and electron backscatter diffraction (EBSD). The crystal structure of the pearlitic steel is composed of “pearlitic colonies” that have the same lamellar structure direction and “pearlitic blocks” that have the same ferrite crystal direction. The SEM and EBSD results revealed that the crack initiation depends on the pearlitic colonies. Therefore, we defined the characteristic dimension for fatigue crack initiation as the pearlitic colony size. However, for safety purposes, the pearlitic block size should be considered the engineering definition of the fatigue crack initiation unit, since decreasing the pearlitic block size should cause an improvement in the fatigue limit of pearlitic steel. 相似文献
662.
Yuki Orikasa Daiko Takamatsu Kentaro Yamamoto Yukinori Koyama Shinichiro Mori Titus Masese Takuya Mori Taketoshi Minato Hajime Tanida Tomoya Uruga Zempachi Ogumi Yoshiharu Uchimoto 《Advanced Materials Interfaces》2014,1(9)
Surface coating on lithium‐ion battery cathodes improves their durability at high potentials, which is a well‐known practical application. However, the mechanism is still unclear because the coating influences the electrode/electrolyte interface at a few nanometer‐scale and direct observation of the interface under real operating conditions of a battery is challenging. This study reveals the mechanism of the surface coating effect on lithium‐ion battery cathodes by using in operando X‐ray absorption spectroscopy (XAS) on well‐defined MgO‐coated LiCoO2 thin‐film electrodes prepared via pulsed laser deposition. Total‐reflection in operando XAS measurements reveal that LiCoO2 forms a reductive phase at the interface between the uncoated‐LiCoO2 electrode and the electrolyte, while the MgO coating layer inhibits the redox process, leading to an improvement in the cycle performance of the battery. Depth‐resolved in operando XAS measurements indicate that a solid solution of the magnesium phase forms at the LiCoO2 surface upon MgO coating. Magnesium ions function as pillars to stabilize the layered structure at the interface between the LiCoO2 electrode and the electrolyte for delithiated states upon cycling at potentials. 相似文献
663.
Effect of primary structure on permselectivity of ultrathin semipermeable polybenzimidazole membrane
Motohiro Aiba Takahiro Tokuyama Hidetoshi Matsumoto Hiroki Tomioka Tomoya Higashihara Mitsuru Ueda 《应用聚合物科学杂志》2015,132(9)
A series of polybenzimidazoles (PBIs) with different main chains and sulfonated PBI were successfully synthesized from the corresponding dicarboxylic acids and 3,3'‐diaminobenzidine for the formation of ultrathin, single‐component, and semipermeable membranes. Furthermore, the covalently crosslinked PBI membrane was prepared by the reaction of sulfonated PBI with divinyl sulfone. Their water transport properties were evaluated under a reverse osmosis mode and compared with the primary structure based on the water permeability (A) and salt permeability (B) values normalized by the membrane thickness. It was found that the A and B values of the PBIs were improved with increasing the weight ratio of the imidazole rings per repeating unit, the introduction of sulfonate group as the hydrophilic group to the PBI was an effective way to enhance the A value, and the crosslinked structure enhanced the salt rejection rate (R) value while maintaining the water flux. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41531. 相似文献
664.
Moonmangmee S Kawabata K Tanaka S Toyama H Adachi O Matsushita K 《Journal of Bioscience and Bioengineering》2002,93(2):192-200
Acetobacter aceti IFO 3284 has been shown to have two types of strains: one forms a smooth-surfaced colony (S strain) and the other forms a rough-surfaced colony (R strain) (Matsushita et al., 1992). In this study, both S and R strains were isolated and characterized. The S strain grew well in submerged culture but very poorly in static culture. In contrast, the R strain grew well in static culture by floating on the surface of the culture medium, as well as in shaking submerged culture. Scanning electron microscopy revealed that the R strain was covered by some amorphous materials that were not seen in the S strain. The R strain produced 5-fold higher levels of sugars related to polysaccharides responsible for pellicle formation than the S strain did. Unlike cellulose of Acetobacter xylinum, the polysaccharides of the R strain were cellulase-resistant and alkaline-sensitive. The polysaccharides were not secreted into the culture medium, and more than 90% of them were retained in the membrane fraction when the cells were disrupted under mild conditions by lysozyme treatment. Furthermore, the polysaccharides were shown to be mainly attached to the outer membrane when separated. After solubilization with beta-octylglucoside, the membrane-attached polysaccharides were purified by several steps including enzyme treatment, column chromatography and alcohol precipitation. The purified polysaccharide was estimated to have an apparent molecular mass of 700-kDa based on Sephacryl S-500 column chromatography, and to be composed of two monosaccharides, glucose and rhamnose, at an approximately equimolar ratio. Thus, in this study, we clarified that the A. aceti R strain produced a polysaccharide associated with the flotation of the cells on the medium surface, like A. xylinum, and that the polysaccharide was a novel one consisting of glucose and rhamnose. 相似文献
665.
Yoshida Tomonori Muto Daiki Tamai Tomoya Suzuki Shinsuke 《Metallurgical and Materials Transactions A》2018,49(6):2463-2470
Metallurgical and Materials Transactions A - Porous aluminum alloy with aligned unidirectional pores was fabricated by dipping A1050 tubes into A6061 semi-solid slurry. The porous aluminum alloy... 相似文献
666.
Satoshi Seino Yasuo Imoto Daijiro Kitagawa Yoshiki Kubo Tomoya Kosaka Takao Kojima 《Journal of Nuclear Science and Technology》2016,53(7):1021-1027
This paper presents a new technique for synthesizing silver nanoparticles immobilized on textile fabrics using a radiochemical process. In this process, the irradiation of a high-energy electron beam on an aqueous solution containing silver ions induces a reducing reaction that forms metallic silver nanoparticles. Small Ag particles of about 2–4 nm were observed together with relatively large particles of more than 10 nm. These nanoparticles are firmly immobilized on the surface of a support textile fabric without the need for any binder or surfactant. The amount of silver nanoparticles immobilized was found to depend on the water content of the support textile fabric, suggesting that the silver ions are reduced not only by radiochemical species generated by the radiolysis of water, but also by radiochemical species generated in the irradiated support fabric itself. The silver nanoparticles that were immobilized on the support textile fabric exhibited an excellent antibacterial activity across a wide antibacterial spectrum, even after a durability test involving washing the fabric 100 times. 相似文献
667.
Nakamura Keita Hanari Toshihide Kawabata Kuniaki Baba Keita 《Artificial Life and Robotics》2023,28(2):352-360
Artificial Life and Robotics - Photogrammetry is a three-dimensional (3D) reconstruction from images. In photogrammetry, when each image captures the features of the target object for 3D... 相似文献
668.
669.
Norimitsu Sakagami Michitaka Kawabata Kenshiro Yokoi Shinji Matsuda Atsushi Mitsui Ko Sano Sadao Kawamura 《野外机器人技术杂志》2023,40(8):1906-1926
As described in this paper, we investigate the sediment penetration performance of a portable underwater robot with a helical screw pipe using marine thrusters with limited force. First, we derive a mathematical model based on an empirical and simple method using the undrained shear strength of cohesive soil to provide a rough estimate of maximum penetration depths. Then, we perform numerical analysis for estimating the maximum depth of sediment penetration and for designing a sampling pipe. Additionally, we use experimentation to investigate the relation between the penetration depth of the helical screw pipe and the force of marine thrusters mounted on the portable underwater robot. After testing the penetration performance in a water tank, we conduct a field experiment at Lake Biwa and obtain results of the penetration depths. The maximum penetration into the lake sediment is at least 0.30 m. The results demonstrated the possibility of using the derived mathematical model to make a rough estimation of the maximum penetration depth for clay sediments. Additionally, we can use non-powerful thrusters equipped with small autonomous underwater vehicles (AUVs) and remotely operated vehicles (ROVs) for sediment sampling. The proposed method is also applicable for the installation of underwater sensors using small AUVs and ROVs. 相似文献
670.