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991.
Hayao Imamura Mitsuya Kusuhara Shoko Minami Masayoshi Matsumoto Kazuo Masanari Yoshihisa Sakata Keiji Itoh Toshiharu Fukunaga 《Acta Materialia》2003,51(20):6407-6414
Nanocomposites obtained by mechanical milling of graphite and magnesium with organic additives (benzene, cyclohexene or cyclohexane) have been studied with the aim of preparing novel hydrogen storage materials. The organic additives were very important in the milling processes to determine the characteristics of the resulting carbon nanocomposites. The mechanical milling with high energy resulted in the generation of large amounts of dangling carbon bonds in graphite with simultaneous decomposition of graphite structure. Such dangling bonds of carbon acted as sites to take up hydrogen. It has been proved by temperature programmed desorption (TPD) and neutron diffraction measurements that the hydrogen taken up in the nanocomposites exists in at least two states; in the form of C–H bond formation in the graphite component and in the form of hydride in the magnesium component. The relative amounts of two types of hydrogen strongly depended upon differences in additives used (benzene, cyclohexene or cyclohexane). When C6D6 besides C6H6 was used as additive, the hydrogen taken up was discussed from the standpoint of isotope effects. Upon addition of titanium tetraisopropoxide, the features of hydrogen uptake by the nanocomposites changed completely. 相似文献
992.
993.
Tadashige Sakai Masaharu Matsumoto Tomoyuki Murakami Yoshihiro Okuno 《Electrical Engineering in Japan》2012,179(3):23-30
The power generation characteristics of a disk magnetohydrodynamics (MHD) generator with high‐temperature inert gas (argon) plasma have been examined by a time‐dependent two‐dimensional numerical simulation. The numerical simulation results based on the experimental conditions show that the enthalpy extraction ratio (= electrical output power/thermal input) can reach above 10%, which surely supports the reasonability of the experimental results. Proper selection of working conditions, especially the inlet total gas temperature, is necessary, since the gas temperature dominantly determines the electrical conductivity in the generator, unlike the conventional seeded plasma MHD generator. It is also found that the plasma is not in the recombination process but in the ionization process, where the ionization degree moderately increases along the flow. © 2012 Wiley Periodicals, Inc. Electr Eng Jpn, 179(3): 23–30, 2012; Published online in Wiley Online Library ( wileyonlinelibrary.com ). DOI 10.1002/eej.21237 相似文献
994.
Hiroaki Matsumoto Daiki Naito Kento Miyoshi Kenta Yamanaka Akihiko Chiba Yoko Yamabe-Mitarai 《Science and Technology of Advanced Materials》2013,14(1):893-904
AbstractThis work identifies microstructural conversion mechanisms during hot deformation (at temperatures ranging from 750 °C to 1050 °C and strain rates ranging from 10?3 s?1 to 1 s?1) of a Ti-5Al-2Sn-2Zr-4Mo-4Cr (Ti-17) alloy with a lamellar starting microstructure and establishes constitutive formulae for predicting the microstructural evolution using finite-element analysis. In the α phase, lamellae kinking is the dominant mode in the higher strain rate region and dynamic globularization frequently occurs at higher temperatures. In the β phase, continuous dynamic recrystallization is the dominant mode below the transition temperature, Tβ (880~890 °C). Dynamic recovery tends to be more active at conditions of lower strain rates and higher temperatures. At temperatures above Tβ, continuous dynamic recrystallization of the β phase frequently occurs, especially in the lower strain rate region. A set of constitutive equations modeling the microstructural evolution and processing map characteristic are established by optimizing the experimental data and were later implemented in the DEFORM-3D software package. There is a satisfactory agreement between the experimental and simulated results, indicating that the established series of constitutive models can be used to reliably predict the properties of a Ti-17 alloy after forging in the (α+β) region. 相似文献
995.
Kazuhide Matsumoto Yoshiyasu Itoh Tsuneji Kameda 《Science and Technology of Advanced Materials》2013,14(2):153-158
Thermal barrier coatings (TBCs) are being developed for the key technology of gas turbine and diesel engine applications. In general, 8 mass% Y2O3–ZrO2 (8YSZ) coating materials are used as the top coating of TBCs. The development of hafnia-based TBC was started in order to realize the high reliability and durability in comparison with 8YSZ, and the 7.5 mass% Y2O3–HfO2 (7.5YSH) was selected for coating material. By the investigation of electron-beam physical vapor deposition (EB-PVD) process using 7.5YSH ceramic ingot, 7.5YSH top coating with about 200 µm thickness could be formed. The microstructure of the 7.5YSH coated at coating temperature of 850 °C showed columnars of laminated thin crystals. On the other hand, the structure of the 7.5YSH coated at coating temperature of 950 °C showed solid columnars. From the result of sintering behavior obtained by heating test of 7.5YSH coating, it was recognized that the thermal durability of 7.5YSH coating was improved up to about 100 °C in comparison with 8YSZ coating. This tendency was confirmed by the experimental result of the thermal expansion characteristics of sintered 7.5YSH and 8YSZ.©2003 Elsevier Science Ltd. All rights reserved. 相似文献
996.
This paper proposes very simple bit-interleaved coded modulation with iterative detection (BICM-ID) as a spectrally efficient signal transmission scheme, where irregular repetition code and extended mapping with rate-1 doped accumulator (ACC) are combined to achieve a clear turbo-cliff. Doped ACC is used for close matching of the demapper and decoder??s extrinsic information transfer curves. Although the proposed BICM-ID system is very simple, it can achieve excellent performances and completely eliminate bit-error-rate floor. An exemplifying result for extended non-Gray mapped 4-quadrature amplitude modulation symbol shows that with 0.916 bits/channel use, turbo-cliff happens at 1.27 dB away from the Shannon limit. 相似文献
997.
The objective of this study was to propose a new model for the prediction of the liftoff heights of turbulent flames diluted by the entrainment of burned gases. In combustion furnaces with the internal recirculation of burned gases, mixtures of fuel and oxidizer are diluted with recirculated burned gases through entrainment into the gas jets. We focused on the effects which dilution resulting from entrainment has on the stabilization mechanism of lifted flames. In order to investigate the effects of dilution on liftoff height, we employed a concentric burner incorporating fuel, oxidizer and co-flow gas nozzles. The recirculated burned gas was simulated by co-flow air diluted with either N2 or CO2 gas. Liftoff heights were observed to increase with decreasing O2 concentrations in the co-flow gas when maintaining a constant O2 concentration in the oxidizer, due to dilution resulting from entrainment of the diluted co-flow gas. The liftoff heights obtained with co-flow gases diluted by CO2 were greater than those obtained when diluting with N2 due to both thermal and chemical dilution effects. The conventional premixed model was not able to predict the liftoff trends observed in this study and we therefore propose a modified premixed model which takes into account the dilution effect resulting from entrainment. In this model, the amount of entrained co-flow gas is evaluated according to the self-similarity law of a round jet. Non-dimensional liftoff heights based on this modified model exhibit excellent linear correlation with non-dimensional fuel gas velocities, even when various co-flow gases are used for dilution. The conventional large eddy model was also modified in the same manner and the results obtained from the modified model exhibit satisfactory correlation. 相似文献
998.
A pair of carbohydrate model compounds, methyl β-d-glucopyranoside (MGP) and a deuterated MGP labeled at each C-H bond, was reacted with active oxygen species (AOS) generated from reactions between O2 and a co-existing phenolic compound, 2,4,6-trimethylphenol (TMPh) or 4-hydroxy-3-methoxybenzyl alcohol (vanillyl alcohol, Valc), under O2 delignification conditions. The pair were also reacted with O? generated in the alkaline H2O2 treatment with the addition of FeCl3. Clear kinetic isotope effects were observed only in the reactions of two pairs using the deuterated MGPs labeled at the anomeric and C-2 positions in this system. These results suggest that at least a specific AOS is generated only in this system and that a major AOS in the O2-Valc system is highly reactive O?. It is also suggested that the AOS specifically generated only in this system is a peroxyl radical derived by the combination reaction between the TMPh phenoxyl radical and O2. 相似文献
999.
Jinzhao Lyu Yoshiya Hashimoto Yoshitomo Honda Naoyuki Matsumoto 《International journal of molecular sciences》2021,22(17)
Scaffolds stimulate cell proliferation and differentiation and play major roles in providing growth and nutrition factors in the repair of bone defects. We used the recombinant peptide Cellnest™ to prepare the three-dimensional stem cell complex, CellSaic, and evaluated whether CellSaic containing rat dental pulp stem cells (rDPSCs) was better than that containing rat bone marrow stem cells (rBMSCs). rDPSC-CellSaic or rBMSC-CellSaic, cultured with or without osteogenic induction medium, formed the experimental and control groups, respectively. Osteoblast differentiation was evaluated in vitro and transplanted into a rat model with a congenital jaw fracture. Specimens were collected and evaluated by microradiology and histological analysis. In the experimental group, the amount of calcium deposits, expression levels of bone-related genes (RUNX2, ALP, BSP, and COL1), and volume of mineralized tissue, were significantly higher than those in the control group (p < 0.05). Both differentiated and undifferentiated rDPSC-CellSaic and only the differentiated rBMSC-CellSaic could induce the formation of new bone tissue. Overall, rBMSC-CellSaic and rDPSC-CellSaic made with Cellnest™ as a scaffold, provide excellent support for promoting bone regeneration in rat mandibular congenital defects. Additionally, rDPSC-CellSaic seems a better source for craniofacial bone defect repair than rBMSC-CellSaic, suggesting the possibility of using DPSCs in bone tissue regenerative therapy. 相似文献
1000.
K. Yasuda M. Niraula H. Oka T. Yoneyama K. Matsumoto H. Nakashima T. Nakanishi D. Katoh Y. Agata 《Journal of Electronic Materials》2010,39(7):1118-1123
Electrical properties of halogen-doped CdTe layers grown on Si substrates using iodine and chlorine dopants are presented.
No change in electrical properties of the layers was observed with chlorine as a dopant. However, doping with iodine resulted
in highly conductive n-type layers or highly resistive p-type layers depending upon the growth conditions, even though a similar amount of dopant was introduced into the growth chamber.
Layers grown at 560°C, with a vapor-phase Te/Cd precursor ratio of 3.0, were p-type. The resistivity of the layers remained unchanged for low dopant supply rates, but increased abruptly when the dopant
supply rate was increased beyond a certain value. On the other hand, layers grown at 325°C with Te/Cd ratios from 0.1 to 0.25
were n-type. A maximum free electron concentration of 1.3 × 1017 cm−3 was obtained at room temperature. The types and conductivities of the grown layers were strongly dependent on the growth
conditions. 相似文献