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排序方式: 共有321条查询结果,搜索用时 234 毫秒
91.
92.
Blowing snow at Mizuho station, Antarctica 总被引:2,自引:0,他引:2
Nishimura K Nemoto M 《Philosophical transactions. Series A, Mathematical, physical, and engineering sciences》2005,363(1832):1647-1662
Blowing snow observations were carried out at Mizuho station, Antarctica, from October to November 2000. A blowing snow observation system including snow particle counters, which can sense not only the number of snow particles, but also their diameters, was situated on a 30 m tower. All instruments worked correctly and the data obtained revealed profiles of mass flux and particle size distributions as a function of the friction velocity. Measurements were compared with a blowing snow model that accounted for most physical processes including aerodynamic entrainment, grain/bed collisions, wind modification, particle size distribution and turbulent fluctuations on the particle trajectories. Simulated and measured results showed close agreement, and the validity of the model was demonstrated. Vertical profiles of horizontal mass flux from saltation to suspension, as well as the particle size distributions were expressed precisely, which could not be achieved using the previous models. 相似文献
93.
The modifications of dip-coated lead titanate (PT) and lead zirconate titanate (PZT) films strongly depend on the film thickness and the substrate in addition to the heat-treatment temperature. At 500 to 600 ° C, metastable paraelectric pyrochlore grew on glass plates (amorphous plates) when the thickness of the coated films produced by one coating cycle was below 100 nm, while ferroelectric perovskite formed on crystalline substrates or when thick films were coated on amorphous plates. This tendency is discussed in terms of an inhomogeneous reaction and the epitaxial effect. The perovskite PT films coated on single-crystal SrTiO3 plate at 700 ° C were strongly oriented to thec-axis. 相似文献
94.
Makoto Takeuchi Kouichi Kamiyama Katsuaki Suganuma 《Journal of Electronic Materials》2006,35(11):1918-1925
In the electronics industry, lead-free solder processes such as the terminal plating of electronic components, fine pitch
connectors, and flexible printed circuits (FPCs) are invariably hampered by the serious problem of tin whisker formation.
Here, a new and simple method, the JVC Micro Island (JMI) process, is proposed for the prevention of tin whisker formation
in fine pitch connectors. Briefly, the base copper terminal was acid etched to afford a roughened surface, which was then
tin plated. The contact test with Knoop indentation proved the effectiveness of the present process. The maximum length of
the as-formed tin whiskers was less than 50 μm. The solderability of the JMI FPCs was not influenced by the present process.
Thus, the new JMI process is shown to have a great advantage for the prevention of tin whisker formation in fine pitch connectors. 相似文献
95.
Hashimoto S. Hara K. Funato H. Kamiyama K. 《Industry Applications, IEEE Transactions on》2001,37(3):806-811
In vibration suppression control with a wide bandwidth for a resonant plant, it is a requisite to identify the plant with high accuracy. However, the more complicated the plant is, the more difficult its system identification becomes. This paper proposes the identification of a modified plant instead of the original plant. The modified plant is a minor control loop (MCL), considering the original plant, when one of the output values is the control feedback. The MCL is designed in order to obtain an optimal damping factor of the modified plant. Moreover, the modified plant is identified based on the autoregressive exogenous (ARX) model and the least-squares method. Based on these techniques, it is possible to specify an exact uncertainty between the nominal and identified parameters of the ARX model. Therefore, a robust vibration suppression control system, which has a wide frequency band, can be systematically designed. The advantages of the proposed design method for a two-mass resonant system are demonstrated through simulations and experiments in the cases of the position and speed control 相似文献
96.
A. Forrai T. Tanoi S. Hashimoto H. Funato K. Kamiyama 《Electrical Engineering (Archiv fur Elektrotechnik)》2001,83(4):179-186
Contents The paper deals with robust controller design for motion control systems in case of constraints on the control signal. Furthermore,
in order to enhance the dynamic performances of the designed control system – in case of limitation of the control signal
– gain-scheduled control strategy is considered. The proposed robust controller design approach is verified by experimental
results in case of a vector controlled brushless d.c. drive.
Received: 11 February 2001 相似文献
97.
Keiichi Kamada Kouichi Nawashiro Fumiyasu Tamagawa Cha-Yeol Lee Hiroshi Yoshida Sunao Kawasaki Ritoku Ando Masaru Masuzaki 《Journal of Infrared, Millimeter and Terahertz Waves》2000,21(9):1441-1449
A relativistic electron beam (500 keV, 200 A, 10 ns) generated magnetically tunable microwave radiation in a frequency range of 9-13 GHz when it is injected into an X-band rectangular waveguide immersed in a uniform axial magnetic field (4-10 kG). The mechanism of the microwave radiation was identified as the gyrotron backward wave interaction. The output power of the radiated microwave increased exponentially with the increase of the cavity length. 相似文献
98.
Soichiro Fujiki Shinya Aoi Tetsuro Funato Nozomi Tomita Kei Senda Kazuo Tsuchiya 《Journal of the Royal Society Interface》2015,12(110)
Human walking behaviour adaptation strategies have previously been examined using split-belt treadmills, which have two parallel independently controlled belts. In such human split-belt treadmill walking, two types of adaptations have been identified: early and late. Early-type adaptations appear as rapid changes in interlimb and intralimb coordination activities when the belt speeds of the treadmill change between tied (same speed for both belts) and split-belt (different speeds for each belt) configurations. By contrast, late-type adaptations occur after the early-type adaptations as a gradual change and only involve interlimb coordination. Furthermore, interlimb coordination shows after-effects that are related to these adaptations. It has been suggested that these adaptations are governed primarily by the spinal cord and cerebellum, but the underlying mechanism remains unclear. Because various physiological findings suggest that foot contact timing is crucial to adaptive locomotion, this paper reports on the development of a two-layered control model for walking composed of spinal and cerebellar models, and on its use as the focus of our control model. The spinal model generates rhythmic motor commands using an oscillator network based on a central pattern generator and modulates the commands formulated in immediate response to foot contact, while the cerebellar model modifies motor commands through learning based on error information related to differences between the predicted and actual foot contact timings of each leg. We investigated adaptive behaviour and its mechanism by split-belt treadmill walking experiments using both computer simulations and an experimental bipedal robot. Our results showed that the robot exhibited rapid changes in interlimb and intralimb coordination that were similar to the early-type adaptations observed in humans. In addition, despite the lack of direct interlimb coordination control, gradual changes and after-effects in the interlimb coordination appeared in a manner that was similar to the late-type adaptations and after-effects observed in humans. The adaptation results of the robot were then evaluated in comparison with human split-belt treadmill walking, and the adaptation mechanism was clarified from a dynamic viewpoint. 相似文献
99.
Koji Miki Hiroki Hashimoto Tatsuhiro Inoue Hideki Matsuoka Hiroshi Harada Masahiro Hiraoka Kouichi Ohe 《Small (Weinheim an der Bergstrasse, Germany)》2014,10(15):3119-3130
In this study, amphiphilic Janus‐type polymers were synthesized via ring‐opening metathesis polymerization (ROMP), multiple vicinal diol formation, and grafting of poly(ethylene glycol) monomethyl ether (mPEG). These amphiphilic polymers formed self‐assemblies, which were a mixture of micelles and multimicellar aggregates, in water. By choosing suitable Janus‐type polymers and irradiating an aqueous solution of polymers using a sonicator, either small micelles or large multimicellar aggregates were obtained selectively. Hydrophobic substituents controlled the aggregation–disaggregation behavior, leading to the formation of metastable self‐assemblies by sonication. The formation of self‐assemblies with a uniform size was affected by ultrasonic frequency, rather than power. In vivo optical tumor imaging revealed that the large‐size multimicellar aggregates persisting for a long time in blood circulation slowly accumulated in tumor tissues. In contrast, the tumor site was rapidly, clearly visualized using the small‐size micelles. 相似文献
100.
Kouichi Genda Naoaki Yamanaka Yoshimitsu Arai Hideki Kataoka 《International Journal of Communication Systems》1994,7(3):223-229
This paper proposes a high-speed ATM switch architecture for handling cell rates of several Gb/s in a broadband communication switching system or cross-connect system. The proposed switch architecture, named the high-speed-retry banyan switch, employs a bufferless banyan network between input and output buffers; a cell is repeatedly transmitted from an input buffer until it can be successfully transmitted to the desired output buffer. A simple cell-retransmission algorithm, is employed as is a ring-arbitration algorithm for cell conflict. They are suitable for FIFO type buffers and bufferless highspeed devices. Good traffic characteristics which are independent of switch size are achieved for an internal speed ratio of only four times the input line speed. A prototype system with the internal speed of 1·2 Gb/s is constructed in order to confirm the basic operation of the high-speed-retry banyan switch. The prototype system, even in its present state, could be used to realize a giga-bit-rate BISDN switching system. 相似文献