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排序方式: 共有1380条查询结果,搜索用时 15 毫秒
41.
Shigeru Tanaka Kazuyuki Hokamoto Seiichi Irie Toshihiko Okano Zoran Ren Matej Vesenjak Shigeru Itoh 《Measurement》2011,44(10):2185-2189
Porous materials such as aluminum foam have been investigated for possible use as impact shock absorbers in transportation aeronautic applications. However, the response of aluminum foam during impacts at high velocities of more than 100 m/s is not yet fully understood. A high-velocity impact experiment was therefore carried out to clarify impact shock absorption properties of aluminum foam. A one-stage powder gun was used to accelerate an aluminum foam sample to impact a rigid wall. Velocity and deformation of the aluminum foam sample during impact was studied using a digital high-speed video camera, while the pressure wave in the aluminum foam sample was measured using a PVDF gauge. The experimental observations revealed uneven collapse of the aluminum foam sample structure during high speed impact with a general stress plateau effect, typical for cellular material structures when subjected to quasi-static loading. 相似文献
42.
Phase relations for the Al2O3-CaF2-SiO2 system were investigated from 1673 to 1723 K. The hotfilament technique was applied to observe a two-liquid region and liquidus
for the ternary system. The liquidus saturated with SiO2 was investigated at 1673 K by using the hot-filament technique and the chemical equilibrium technique. In this system, the
addition of Al2O3 to the CaF2-SiO2 system reduces the congruent temperature. A small substitution of Al2O3 for CaF2 increases the solubility of SiO2, namely, if the region of liquid phase could be enlarged. These results suggest that Al2O3 would be an effective substitute of CaF2 in slag for steelmaking. 相似文献
43.
Shigeru Hanba 《国际强度与非线性控制杂志
》2008,18(17):1592-1606
》2008,18(17):1592-1606
In constructing a globally convergent numerical nonlinear observer of Newton‐type for a continuous‐time nonlinear system, a globally convergent nonlinear equation solver with a guaranteed rate of convergence is necessary. In particular, the solver should be Jacobian free, because an analytic form of the state transition map of the nonlinear system is generally unavailable. In this paper, two Jacobian‐free nonlinear equation solvers of pseudo‐Newton type that fulfill these requirements are proposed. One of them is based on the finite difference approximation of the Jacobian with variable step size together with the line search. The other uses a similar idea, but the estimate of the Jacobian is mostly updated through a BFGS‐type law. Then, by using these solvers, globally stable numerical nonlinear observers are constructed. Numerical results are included to illustrate the effectiveness of the proposed methods. Copyright © 2007 John Wiley & Sons, Ltd. 相似文献
44.
Hiroshi Aoyama Kohei Tanaka Hiroyuki Watanabe Nobuo Takeda 《Composite Structures》2001,52(3-4):523-531
Transmitted light could detect matrix cracks that occurred in the early stages of fracture of alumina-fiber-reinforced plastics (alumina-FRPs); these cracks could not be detected by acoustic emission (AE). An optical-fiber Bragg grating (FBG) sensor could detect the matrix cracks but it must be embedded in the FRPs. To determine which wavelength is sensitive to the defects in the FRP, the spectra of the transmitted and reflected light were measured. The intensity of the transmitted light, especially in the visible region (wavelength: 400–800 nm), decreased as the bending stiffness of the test piece decreased. It is thus concluded that to monitor the decrease in bending stiffness of FRPs, a simple sensor using a visible ray is good enough. And this transmitted-light NDE technique can work in the strong electromagentic field associated with a superconductor. It will therefore be useful for detecting defects in the FRP of the load-support system in service. 相似文献
45.
We have investigated the microstructure of the poly(vinyl alcohol) (PVA) films using small- and wide-angle X-ray scattering (SAXS and WAXS, respectively) techniques. The samples were uniaxially drawn in water or KI/I2 aqueous solution and then dried in an air-oven at 333 K for 1 h prior to SAXS and WAXS measurements. It was found that for the films drawn in KI/I2 solution PVA chains in the microfibrillar structure are more extended upon the film drawing compared to the case of the films drawn in pure water, which is resulted from the correlation function analysis on the SAXS data. Adsorbed iodines into the film were anticipated to act as junction points between the microfibrils via the formation of the PVA-iodine complexes. 相似文献
46.
This letter describes the successful fabrication of a 0.95Sn−0.05Au solder microbump on a compound semiconductor wafer by
reflowing of multi-layer metal film. Since the inherent interdiffusion in Au−Sn phases results in the alloying of multi-layer
films, the composition of micro-bump is well controlled by the thickness of constituent metal films. The micro-bumps melt
at about 220 C, which is close to the lowest eutectic temperature in a Au−Sn system. Solder bonding using 0.95Sn−0.05Au micro-bump
is a very useful technique for the flipchip bonding of compound semiconductor devices. 相似文献
47.
Shigeru Okada Toetsu Shishido Takao Mori Kiyokata Iizumi Kunio Kudou Kazuo Nakajima 《Journal of Alloys and Compounds》2008,458(1-2):297-301
LEAlB14 (orthorhombic, Imam) (LE = Li, Mg) crystals were grown using metal salts (Li2CO3, LiF, LiI, MgO, MgF2, MgI2) and crystalline boron from a high-temperature aluminium metal flux. The growth conditions for growing LEAlB14 were established using the starting mixtures of B/LE = 2.0, and Al metal was added to each mixture at a mass ratio of 1:15–20. LEAlB14 crystals from the Al-self flux using metal salts could be obtained from all the different salts. The maximum dimensions of LiAlB14 and MgAlB14 crystals were approximately 18 and 12 mm for the crystals obtained from LiF and MgF2. The unit-cell parameters of as-grown LEAlB14 are as follows: for LiAlB14, obtained from LiF, a = 0.5846 (2) nm, b = 0.8144 (2) nm, c = 1.0355 (3) nm, V = 0.4930 (2) nm3: for MgAlB14, obtained from MgF2, a = 0.5845 (2) nm, b = 0.8114 (2) nm, c = 1.0330 (3) nm, V = 0.4899 (3) nm3. Microhardness, oxidation resistance and magnetic susceptibility of these materials are described in detail. 相似文献
48.
49.
One of the most important technologies for electric vehicles (EVs) will be drive control technology for the main motor. It is desired that the drive control technology have the following characteristics. (1) It does not require a position/speed sensor for controlling motor drive, which has been mounted on the rotor shaft. (2) It has vector controls that can produce torque quickly, efficiently, and/or precisely. (3) It has wide driving‐range and allows developing EVs with no variable transmission. This paper proposes new drive control technologies for such EVs using a permanent‐magnet synchronous motor as a main motor, and verifies its usefulness through development of an actual EV that can drive on public roads. © 2008 Wiley Periodicals, Inc. Electr Eng Jpn, 165(3): 83–94, 2008; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20459 相似文献
50.
Air-core photonic bandgap fibers offer many unique properties and are critical to many emerging applications. A notable property is the high nonlinear threshold which provides a foundation for applications at high peak powers. The strong interaction of light and air is also essential for a number of emerging applications, especially those based on nonlinear interactions and spectroscopy. For many of those applications, much wider transmission bandwidths are desired to accommodate a wider tuning range or the large number of optical wavelengths involved. Presently, air-core photonic bandgap fibers have a cladding of hexagonal lattice. The densely packed geometry of hexagonal stacking does not allow large nodes in the cladding, which would provide a further increase of photonic bandgaps. On the other hand, a photonic cladding with a square lattice can potentially provide much larger nodes and consequently wider bandgap. In this work, the potentials of much wider bandgap with square lattice cladding is theoretically studied and experimentally demonstrated. 相似文献