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排序方式: 共有898条查询结果,搜索用时 15 毫秒
811.
Yoko Okahisa Keisuke Kojiro Tomoaki Kiryu Takahiro Oki Yuzo Furuta Chizuru Hongo 《Journal of Materials Science》2018,53(6):3972-3980
In Asian countries, only bamboo culms that are 3–5 years old are used especially as materials because of their toughness, pliability, and/or workability. In this study, we evaluated the mechanical properties of bamboo in correlation with age-dependent changes in the nanostructures of cell walls, such as microfibril angles (MFAs), crystallite sizes, and crystallinity. Current year and 1.5-, 3.5-, 4.5-, 6.5-, and 8.5-year-old Phyllostachys pubescens samples were used. Three-point bending tests and wide-angle X-ray scattering experiments were conducted. The specific bending of Young’s modulus and the specific bending strength of 3.5- and 4.5-year-old bamboo samples were greater than those of other ages. The MFAs decreased in 1.5-year-old bamboo, were constant until samples were 6.5-years old, and then increased slightly in 8.5-year-old bamboo. The widths of crystallites appeared to be constant for all ages, while the lengths of crystallites and crystallinity showed age-dependent differences only on the inner side. In this study, the MFA was negatively correlated with the toughness of bamboo culms. This result should be considered with other structural features at the tissue level; however, the age-related changes in MFA values appear to be important factors related to the mechanical properties of bamboo. 相似文献
812.
ME Roche MA Anderson RP Oda BL Riggs MA Strausbauch R Okazaki PJ Wettstein JP Landers 《Canadian Metallurgical Quarterly》1998,258(1):87-95
We consider a model of an integrate-and-fire neuron with synaptic current dynamics, in which the synaptic time constant tau' is much smaller than the membrane time constant tau. We calculate analytically the firing frequency of such a neuron for inputs described by a random Gaussian process. We find that the first order correction to the frequency due to tau' is proportional to the square root of the ratio between these time constants radicaltau'/tau. This implies that the correction is important even when the synaptic time constant is small compared with that of the potential. The frequency of a neuron with tau'>0 can be reduced to that of the basic IF neuron (corresponding to tau'=1) using an "effective" threshold which has a linear dependence on radical tau'/tau. Numerical simulations show a very good agreement with the analytical result, and permit an extrapolation of the "effective" threshold to higher orders in radical tau'/tau. The obtained frequency agrees with simulation data for a wide range of parameters. 相似文献
813.
In this paper, we introduce our formalization of the definitions and theorems related to an elliptic curve over a finite prime field. The elliptic curve is important in an elliptic curve cryptosystem whose security is based on the computational complexity of the elliptic curve discrete logarithm problem. 相似文献
814.
Multirobot exploration for search and rescue missions: A report on map building in RoboCupRescue 2009 总被引:1,自引:0,他引:1
Keiji Nagatani Yoshito Okada Naoki Tokunaga Seiga Kiribayashi Kazuya Yoshida Kazunori Ohno Eijiro Takeuchi Satoshi Tadokoro Hidehisa Akiyama Itsuki Noda Tomoaki Yoshida Eiji Koyanagi 《野外机器人技术杂志》2011,28(3):373-387
In the future, mobile robots may be able to assist rescue crews in search and rescue missions that take place in the dangerous environments that result from natural or man‐made disasters. In 2006, we launched a research project to develop mobile robots that can rapidly collect information in the initial stages of a disaster. One of our important objectives is three‐dimensional (3D) mapping, which can be a very useful tool for assisting rescue crews in strategizing rescue missions. To realize this 3D mapping, we identified five issues that we needed to address: (1) autonomous traversal of uneven terrain, (2) development of a system for the continuous acquisition of 3D data of the environment, (3) coverage path planning, (4) centralization of map data obtained by multiple robots, and (5) fusion of map data obtained by multiple robots. We solved each problem through our joint research. Each research institute in our group took charge of solving one of the above issues according to its area of expertise. We integrated these solutions to perform 3D mapping using our tracked vehicle, Kenaf. To validate our integrated autonomous 3D mapping system, we participated in RoboCupRescue 2009 and demonstrated our system using multiple robots on the RoboCupRescue field. In this paper, we introduce our mapping system and report the mapping results obtained at the RoboCupRescue event. © 2011 Wiley Periodicals, Inc. 相似文献
815.
Toshiyuki Nakamiya Tsuyoshi Ueda Tomoaki Ikegami Fumiaki Mitsugi Kenji Ebihara Ryoichi Tsuda 《Diamond and Related Materials》2008,17(7-10):1458-1461
The prepared multi-walled carbon nanotubes (MWCNTs) film was mounted on the holder and the film surface was flashed with a single pulse of Nd:YAG laser (λ = 532 nm) in the air. The dynamics of pulsed nanosecond laser heating process was simulated by the solution of the one-dimensional heat conduction equation. The finite element method (FEM) was applied to solve the equation. At the laser fluence of 1 J/cm2 with Nd:YAG laser, the surface reached the maximum temperature 1503 °C at 13 ns. Moreover, the Raman spectroscopy of MWCNTs films before and after irradiation were measured. The intensity of the two characteristic Raman shifts ID (defect-mode) and IG (graphite-mode) was measured by the Raman spectroscopy. The maximum surface temperature was calculated and compared with the IG/ID ratio of MWCNTs film. The graphitization occurred on the sample after irradiation. 相似文献
816.
Triptycene derivatives bearing a pair of ionophores were synthesized and their rotational behaviors were observed with/without s-block metal cations as an external stimulus. In this study, oxyethylene-based ionophores were introduced at both bridgehead positions of triptycene as the stimulus receptors. The NMR experiments revealed the formation of complexes of the triptycenes with the s-block metal cations. We demonstrated that the rate (activation energy) of the internal rotation of the triptycyl moiety could be controlled by the formation of the complexes. We also found that the conformation of those complexes can be controllable with the species of metal cations. 相似文献
817.
Ronan Prat Toshitugu Suwa Masuhiro Kogoma Satiko Okazaki 《The Journal of Adhesion》1998,66(1):163-182
Adhesive strength of Atmospheric Pressure Glow (APG) plasma-treated polypropylene was studied for various gas mixtures by a scratching test. An explanation of the high adhesive strength obtained after He/N2 APG plasma treatment was given. Formation of carbonyl, alcohol, carboxylic and primary amines was investigated by gas-phase chemical reaction. Their evolution during the ageing of the treated samples was followed. Most changes take place during the first few hours of contact with the atmospheric medium. Contact angle measurements on APG plasma-treated PP were done. These results were compared with PP treated by Silent Electric Discharge (SED). The ageing of the wettability properties of the surface after APG plasmas is better than after SED discharge. 相似文献
818.
Hirooka T. Osawa K. Okazaki M. Nakazawa M. Murai H. 《Photonics Technology Letters, IEEE》2008,20(20):1694-1696
819.
Aritra Sarkar A. Nagesha P. Parameswaran R. Sandhya K. Laha M. Okazaki 《Metallurgical and Materials Transactions A》2017,48(3):953-964
Cumulative fatigue damage under sequential low cycle fatigue (LCF) and high cycle fatigue (HCF) cycling was investigated at 923 K (650 °C) by conducting HCF tests on specimens subjected to prior LCF cycling at various strain amplitudes. Remnant HCF lives were found to decrease drastically with increase in prior fatigue exposure as a result of strong LCF–HCF interactions. The rate of decrease in remnant lives varied as a function of the applied strain amplitude. A threshold damage in terms of prior LCF life-fraction was found, below which no significant LCF–HCF interaction takes place. Similarly, a critical damage during the LCF pre-cycling marking the highest degree of LCF–HCF interaction was identified which was found to depend on the applied strain amplitude. In view of the non-linear damage accumulation behavior, Miner’s linear damage rule proved to be highly non-conservative. Manson’s damage curve approach, suitably modified, was found to be a better alternative for predicting the remnant HCF life. The single constant (β) employed in the model, which reflects the damage accumulation of the material under two/multi-level loading conditions is derived from the regression analysis of the experimental results and validated further. 相似文献
820.
Yuji Honda Tetsuya Yamazaki Naoya Katsumi Naoko Fujita Kenji Matsumoto Masanori Okazaki Shoji Miwa 《Journal of Applied Glycoscience》2019,66(2):51
We investigated the physicochemical properties of starches extracted from 8 lotus (Nelumbo nucifera Gaertn.) rhizomes harvested in different months (September 2012 to May 2013). The physicochemical properties of the lotus starches depended on the harvest date. The peak viscosity (PV) in the Rapid Visco-Analyser analysis, and the viscosity at 65 °C (V65) in the rotational viscometer analysis were significantly lower in SEP starch (extracted from the September-harvested sample) than in the other lotus starches. The Spearman’s rank correlation coefficients of potassium ion (K) content vs. V65 and of K content vs. PV were 0.905 and 0.714, respectively, indicating that potassium ions are important for expressing the pasting properties of lotus starch. Principal component analysis suggested that the potassium, magnesium, calcium, and phosphorus contents are important for displaying both the pasting and gelatinization properties of the lotus starches. Meanwhile, the cluster analysis revealed that physicochemical properties of the SEP starch were different from those of the starches harvested in other months. 相似文献