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91.
92.
Haruyuki Murakami Hiroshi Ueda Atsushi Ishiyama Norikiyo Koizumi Kiyoshi Okuno 《Electrical Engineering in Japan》2010,171(3):7-15
In the ITER Engineering Design Activity (EDA), four NB3Sn model coils were developed and successfully tested. However, it was revealed that the critical current of the conductor degraded with the increase of electromagnetic force. One of the explanations of this phenomenon is a strand bending caused by enormous electromagnetic force. The authors therefore developed a simulation code using the distributed circuit model to investigate dependency of the critical current performance on the periodic bending deformation. The simulation results were in good agreement with the experiments. The dependence of the critical current on the periodic transverse load, temperature, periodic load pitch, thickness of Ta barrier which prevents Cu stabilizer from being contaminated by Sn, twist pitch of the strand, and RRR of the bronze matrix was investigated using the developed code. The results showed that the critical current degraded less with decreasing the pitch of the transverse load and increasing the Ta barrier thickness. It suggests that the shorter cabling pitch and the larger bending stiffness prevent the critical current degradation. © 2010 Wiley Periodicals, Inc. Electr Eng Jpn, 171(3): 7–15, 2010; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20923 相似文献
93.
A method for estimating the sway angle using an observer has already been proposed. The state observer estimates the sway angle accurately and must use the detected sway angle value. However, the estimated sway angle has an error owing to rope length error, friction force, and wind. Moreover, the container mass cannot be determined, and therefore the observer parameter is not suitable. We already proposed robust antisway control for overcoming rope length error without adding a new sensor. Further, we designed a friction disturbance observer to cancel out the influence of the friction force. In this paper, we first propose a container mass estimation method when a crane system performs rolling up control. The observer parameter can be selected using the estimated mass value. Second, in crane parallel shift control, we propose a robust antisway control even when there is a wind disturbance. We design a wind disturbance observer and propose a wind disturbance estimator to separate the friction observer output from the wind disturbance observer output. We confirm through experiments that the proposed method can reduce vibration. 相似文献
94.
You Zhou Tatsuki Ohji Hideki Hyuga Yu‐ichi Yoshizawa Norimitsu Murayama Kiyoshi Hirao 《International Journal of Applied Ceramic Technology》2014,11(5):872-882
Silicon nitride ceramics were prepared from a high‐purity silicon powder doped with 2 mol% Y2O3 and 5 mol% MgO as sintering additives via a route of sintering of reaction‐bonded silicon nitride (SRBSN). The materials sintered at 1900°C for 3, 6, 12, and 24 h had thermal conductivities of 109, 125, 146, and 154 W/m/K, and four‐point bending strengths of 786, 676, 608, and 505 MPa, respectively. The fracture toughness values, determined by the single‐edge‐precracked‐beam (SEPB) method, were 8.4, 8.6, 9.7, and 10.7 MPa m1/2 for the materials sintered for 3, 6, 12, and 24 h, respectively, which were similar to the results measured by the chevron‐notched‐beam (CNB) test method. The materials sintered for longer times (12 and 24 h) showed stronger R‐curve behaviors over longer range of crack extension, in comparison with the materials sintered for shorter times (3 and 6 h). 相似文献
95.
The influence of recycling on the impact damage resistance of recycled carbon fiber‐reinforced polymer (CFRP) composites was investigated using low‐velocity impact and compression after impact (CAI) tests. The relationships among load, force, and time were analyzed to gain insight into the damage characteristics of three types of composite laminate: virgin CF‐reinforced polymer (V‐CFRP), recycled CF‐reinforced polymer (R‐CFRP), and treated recycled CF‐reinforced polymer (TR‐CFRP). Special emphasis was placed on evaluating the extent of damage and the residual mechanical properties as affected by three different fiber surface states. Substantial differences were noted in the shape, area, and damage mode of impact using ultrasonic c‐scanning, photography, and scanning electron microscopy (SEM). V‐CFRP indicated significant improvement in impact damage resistance in the form of less damage, higher residual strength, and greater shear failure angle. Damage resistance was improved up to 80% of V‐CFRP by surface cleaning while R‐CFRP is 50% of V‐CFRP. Shear failure angle of 16° was attained from R‐CFRP and it was increased to 24° when the recycled fibers were cleaned. The result of SEM showed that there was less delamination of TR‐CFRP compared with R‐CFRP. This work proves that the low‐velocity impact response of recycled composites can rival that of virgin composites, while providing a basis for future applications of recycled carbon in many fields. POLYM. COMPOS., 35:1494–1506, 2014. © 2013 Society of Plastics Engineers 相似文献
96.
Ko Ikeda Yoshinori Nakamura Kiyoshi Masumoto Hiromi Shima 《Journal of the American Ceramic Society》1997,80(10):2672-2676
Unpolarized optical spectra were measured in the wavelength range 322–1666 nm by the diffuse reflection technique from spinel powders synthesized in the system MgAl2 O4 –MgCr2 O4 . The spectra were interpreted by the crystal-field theory on the basis of trigonally distorted spinel octahedra with D3d symmetry. For chromium-rich solid solutions, including the MgCr2 O4 end-member, results after peak fittings showed octahedral D3d local symmetry around Cr3+ ions, identical to the crystallographic site symmetry. For chromium-poor solid solutions, however, octahedral C3v local symmetry was suggested around Cr3+ ions, different from the D3d crystallographically expected. 相似文献
97.
Kiyoshi Goto Bernard B. Argent William E. Lee 《Journal of the American Ceramic Society》1997,80(2):461-471
Microstructural analysis of MgO—MgAl2 O4 refractory bricks corroded at 1400–1450°C by calcium aluminosilicate slag reveals secondary spinel, monticellite, merwinite, and MgO as microscopic corrosion products, generally forming in this sequence as the brick is penetrated. The secondary spinel forms an incomplete layer close to (but not at) the MgO grain. Thermodynamic calculations are used to support a detailed model of the corrosion mechanism. 相似文献
98.
To develop insulating materials with a high thermally conductive anisotropy, planarly aligned mesogenic epoxy (ME) resin film was fabricated by uniaxial coating on a hydrophobic polyethylene terephthalate substrate. Grazing incidence small-angle X-ray scattering (GISAXS) and transmission SAXS measurements exhibited that the films spontaneously formed uniaxially aligned monodomain-like smectic structures by curing on the hydrophobic substrate. Then, an in- and out-of-plane thermal conductivity of 10 and 0.048 W m−1 K−1 and outstanding thermal conductivity anisotropy of 208 have been confirmed, respectively. The ME resin films with high thermal conductivity can be applied as insulating materials for multiple-layer electrical and electronic devices. 相似文献
99.
Kiyoshi Hirao Koji Watari Manuel E. Brito Motohiro Toriyama Shuzo Kanzaki 《Journal of the American Ceramic Society》1996,79(9):2485-2488
Silicon nitride was fabricated by tape casting of α-Si3 N4 powder with 5 wt% Y2 O3 and 5 vol% rodlike β-Si3 N4 seed particles, followed by tape stacking, hot pressing under 40 MPa, and annealing at 1850°C for 2-66 h under a nitrogen pressure of 0.9 MPa. Silicon nitrides fabricated by this procedure exhibited a highly anisotropic microstructure with large elongated grains (developed from seed particles) uniaxially oriented parallel to the casting direction. Thermal conductivities parallel to the grain alignment were much higher than those measured in other directions and exhibited high values of up to 120 W/(m.K). The anisotropic thermal conductivity of the specimen could be explained by the rule of mixture, considering that large elongated grains developed from seeds have higher thermal conductivity than a small-grained matrix. 相似文献
100.
Yoshitoshi Saito Shigeo Hayashi Atsuo Yasumori Kiyoshi Okada 《Journal of Porous Materials》1996,3(4):233-239
This paper describes the effects of calcining conditions of kaolinite on pore structures of the porous materials obtained from the selective leaching of calcined kaolinite using KOH solution. Mesoporous -Al2O3 was the predominant crystalline phase in the samples calcined in the temperature range between 950°C and 1050°C for 24 h. The mean specific surface area of these samples was approximately 250 m2 · g–1 and the mean total pore volume was approximately 0.8 ml · g–1. The pore size distribution curves of these samples showed a sharp peak at around 2–3 nm pore radius. This peak was sharper for the sample calcined at 1000°C for 24 h. On the other hand, the pore sizes of the sample calcined at 1100°C for 24 h increased abruptly to 10–20 nm and this change corresponded to the formation of mullite in the sample. The pore sizes of the samples calcined at 1100°C varied with calcining time. The specific surface area and total pore volume decreased, the longer the calcining time of the samples, and this was correlated with an increase in the amount of mullite in the samples. 相似文献