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排序方式: 共有791条查询结果,搜索用时 31 毫秒
51.
Cheng Liu Peng Liu Keisuke Kobayashi Clive A. Randall 《Journal of Electroceramics》2014,32(4):301-306
A NaF-Nb2O5 flux doped (Na,K)NbO3 (NKN) based lead-free ceramic was successfully co-fired with nickel inner electrodes in reduced atmospheres. No chemical reactions and/or inter-diffusion were detected at the interface between the nickel (Ni) electrodes and the NKN-based piezoelectrics. Dielectric, resistivity, and electromechanical performance were measured with processing under different firing conditions and flux additions to obtain high densities. Ceramics are obtained with submicron grain structures with the NaF-Nb2O5 sintering aids (2 and 4 wt%) fluxes, and high densities when firing at low pO2 (10?10 atms) atmospheres at sintering temperatures ~1150 °C for 2 hours. High resistivities and low losses can be obtained through a second annealing condition at 850 °C and 10?7 atms at 8 hours. High d 33 values (over 350 pm/V) determined under unipolar converse electromechanical measurements were obtained in the simple prototyped co-fired structures to show feasibility towards base metal electrodes in multilayer actuators. 相似文献
52.
Md. Nazrul Islam Keisuke Ando Hidefumi Yamauchi Nobuaki Hattori 《Holz als Roh- und Werkstoff》2009,67(2):129-133
Penetration of liquid by passive impregnation method for Douglas-fir (Pseudotsuga menziesii Franco), sugi (Cryptomeria japonica D. Don) and Japanese larch (Larix leptolepis Gordon) was studied. Effects of initial moisture content of sugi (16, 43 and 70% moisture content) on liquid penetration were also studied. Dried Douglas-fir (mc=14%) and sugi (mc=16%), and green Japanese larch (mc=45%) and sugi (mc=70%) were treated by passive impregnation method for penetration analysis. It was observed that dried sugi had the highest level of liquid penetration both in length (170 mm) and width (8 mm) for all measured sections followed by green sugi, green Japanese larch and dried Douglas-fir. In case of different initial moisture content, the highest absorption (624 kg/m3) and penetration (maximum 87 and 96% at cross and longitudinal surfaces, respectively) was observed for sugi having the lowest initial moisture content under the same passive impregnation conditions. Absorption and penetration decreased with the increase of initial moisture content for sugi. These results could help in designing incising pattern and density, as well as solving the problems related to high initial moisture content of wood for passive impregnation. 相似文献
53.
High-performance polymer photovoltaic devices with inverted structure prepared by thermal lamination
Use of a lamination process for the introduction of Au electrode, instead of conventional metal evaporation, improved the power conversion efficiency (PCE) of inverted-structure photovoltaic devices from 1.6% to 2.6% based on a bulk heterojunction of poly(3-hexylthiophene) (P3HT) and (6,6)-phenyl C61 butyric acid methyl ester (PCBM). X-ray photoelectron spectroscopy indicated that a thin layer of P3HT is spontaneously formed at the air/polymer blend layer interface during the spin-coating process. It is suggested that the vacuum-evaporated gold could destroy the surface-segregated thin layer of P3HT, while the lamination process preserves the surface structure working as an electron-blocking layer. The insertion of a PEDOT:PSS layer, between the metal electrode and polymer layer, in the lamination process further improved the PCE to 3.3% with a short-circuit current density of 9.94 mA cm−2, an open-circuit voltage of 0.60 V, and a fill factor of 55% under AM1.5 100 mW cm−2 irradiation. 相似文献
54.
55.
A new FDTD algorithm is proposed for analyzing ultrasonic pulse propagation in the human body, a problem connected with ESWL (extracorporeal shock wave lithotripsy). In this method, we do not use plane wave approximation but directly employ the original equations, taking into account the Lagrangian to derive new FDTD algorithms. This method is applied to an experimental setup and its numerical model that resembles an actual treatment situation in order to compare the sound pressure distributions obtained numerically with those obtained experimentally. The present method is shown to give clearly better results than the earlier method, from the point of view of the numerical reappearance of a strongly nonlinear waveform. © 2009 Wiley Periodicals, Inc. Electr Eng Jpn, 169(4): 29–36, 2009; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20819 相似文献
56.
Keisuke Fukushima Hiroshi Fujimoto Shinsuke Nakagawa 《Electrical Engineering in Japan》2008,162(1):66-72
In a short‐span seeking‐mode of hard disk drives, the resonance modes are getting crucial obstruction to meet the demand on high‐speed data access. In this paper, a novel vibration suppression perfect tracking control (PTC) method is proposed based on controllable canonical realization. In the proposed method, it is assumed that the plant is modeled as the rigid and primary resonance mode. By using this model, the feed forward controller is designed with PTC by multirate sampling control in order to suppress the primary vibration. Additionally, the higher‐order resonance vibration is attenuated by using the trajectory MHVT. The proposed method achieved 16% faster seeking than MPVT, a conventional method. © 2007 Wiley Periodicals, Inc. Electr Eng Jpn, 162(1): 66–72, 2008; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20546 相似文献
57.
Summary
Introduction of simple alkyl groups at the C-2 nitrogen of chitin and some properties of the resulting N-alkyl-chitins have been examined. Chitosan was fully deacetylated and treated with three kinds of aldehydes, formaldehyde,
acetaldehyde, and pentanal. The Schiff bases of chitosan, whose extents of substitution were dependent on the amount of aldehydes,
were reduced with sodium cyanoborohydride to N-alkylated chitosans. The N-alkyl-chitosans were then transformed into the corresponding N-alkyl-chitins by acetylation with acetic anhydride followed by transesterification to remove partly formed O-acetyl groups. The resulting N-methyl-, ethyl-, and pentyl-chitins were amorphous and showed improved affinity for organic solvents.
Received: 13 December 2001/Revised version: 11 January 2002/Accepted: 17 January 2002 相似文献
58.
59.
Selective copper CVD technique involving hydrogen reduction of hexafluoro acetylacetonate copper has been used to fill vias
for fabricating double-level copper interconnect structure. The surface morphology of selectively deposited copper on copper
substrate of the via bottom depends strongly on via opening process. A two-step via opening process consisting of an reactive
ion etching of the insulating interlayer and a wet removal of the interlayer metal results in smooth copper plug formation
by CVD. Double-level copper interconnect structures have been fabricated using this technique and a via resistance as low
as 100 mΩ has been obtained for a 1 μ diameter via. 相似文献
60.
Robert J. Naumann Glen Haulenbeek Hiroshi Kawamura Keisuke Matsunaga 《Microgravity science and technology》2001,13(2):22-32
An instrumented flow cell in the form of a cylinder with differentially heated end walls and adiabatic sidewalls was flown
on STS-95 as the Japan-US Thermal Science Accelerometer Project (JUSTSAP). The purpose of the experiment was to map disturbances
in the thermal field during the course of a Shuttle mission in order to correlated them with various mission events and to
determine if any global transport could be detected from second order, non-zero time average flows resulting from periodic
accelerations (g-jitter).
Significant disturbances in the thermal field were noted each time the Shuttle changed attitude, such as the maneuver to -Z
solar inertial, which is done periodically for thermal conditioning. Burns from the main thrusters associated with the launch
and retrieval of the Spartan satellite produced overturning flows, as might be expected. During extended periods in which
the attitude was held constant, the perturbations to the thermal field correlate extremely well with calculated accelerations
from gravity gradient and drag. Fair agreement was found between the observed temperature perturbations and those predicted
from a modification of the analytical model developed by Bejan and Tien (B&T) for the flow and heat transfer in an infinite
cylinder with a constant axial thermal gradient. A full three-dimensional computational fluid dynamic analysis with more realistic
thermal boundary conditions provided better agreement after adjustments were made to account for the heat flow away from the
measuring thermistors.
Once calibrated with a reliable thermal model, the flow cell was found to serve as a high-precision accelerometer, capable
of measuring the quasi-steady acceleration with a sensitivity of better than 0.1 micro-g in the presence of the higher amplitude
g-jitter typical of Shuttle operations. Further, it was found that the gravity gradient acceleration accounted for virtually
all of the observed quasi-steady accelerations during such extended periods. The thermal response time of the JUSTSAP was
too slow to expect to see the effects of fluctuating first order flows resulting from the vibrational environment of the Shuttle.
However, an indication of a change in the thermal field near the ends of the flow cell was seen during periods of crew exercise
that may possibly be attributed to circulating eddies resulting from the higher order terms in the momentum equation. At higher
amplitudes, these second order effects can produce non-zero time average flows of a global nature, as can the start-up transients
in first-order periodic flows. No such effects were observed, thus it is possible to place an upper limit on the integrated
power spectral density of the vibrational environment experienced as well as the nature of the start-up transients of the
periodic flows. 相似文献