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排序方式: 共有669条查询结果,搜索用时 531 毫秒
61.
Seiji Yamashita Hideo Watanabe Takashi Shirai Masayoshi Fuji Minoru Takahashi 《Advanced Powder Technology》2011,22(2):271-276
We have successfully synthesized zinc oxide microrods perpendicularly oriented on hexagonal ZnO sheets by a simple heat treatment approach using LDH (layered double hydroxide) precursor in an aqueous solution. The synthesized ZnO microrods have an average diameter of 500 nm and length of 2–3 μm, and form highly-oriented array. In this work, the effect of heating temperature and time on morphology and orientation of ZnO microrods was studied experimentally and the formation mechanism was discussed in detail. Transformation from hexagonal precursor to ZnO microrods can be attributed to dissolution and re-precipitation of the precursor, which should be caused by its thermal unstability under heating temperature. 相似文献
62.
The electrical modification of a conductivity-switching polyimide film via molecular layer deposition (MLD) is studied for ultrahigh density data storage based on a scanning probe microscope (SPM). A PMDA-ODA (PMDA = 1, 2, 3, 5-benzenetetracarboxylic anhydride, ODA = 4, 4-oxydianiline) film as a recording medium is uniformly formed from a self-assembled monolayer on a Au surface by MLD. It is demonstrated that the conductivity of the film can be changed by applying a voltage between a SPM probe and the film. This conductivity-switching phenomenon is discussed by the molecular orbital approach and considered to be caused by the charge transfer effect or carrier trapping effect of PMDA-ODA. 相似文献
63.
Norihiro Asada Hidetoshi Matsuki Masayoshi Esashi 《Electrical Engineering in Japan》1995,115(2):115-122
A fail-safe logic circuit must switch the output signal to the logical value “0” when an operation circuit fails. A transformer has such favorable characteristics for fail-safe logic circuits as only the magnetic flux change is transmitted and a superposition of magnetic flux is realized. Thus those characteristics arc applied to a failsafe logic operator. A new fail-safe logic operator using an insulated planar transformer was developed for a fail-safe majority operation and a fail-safe interlocking. In this paper, the principle, structure, design and fundamental characteristics of the new fail-safe logic operator are described. 相似文献
64.
In realization of recursive digital filters with fixed point arithmetic, an error caused by roundoff arises. It is known that
the level of the roundoff noise of an IIR filter tends to be high when the poles are close to the unit circle. Error feedback
(EF) is an effective method to reduce the roundoff noise. It is desirable to design an EF network using as few parameters
as possible in order to keep computational costs low. In this paper, we propose a method for designing a 2D EF network with
identical coefficient sets. That is, the EF coefficients are divided into several subsets such that all the elements within
each set have the same absolute value. In order to optimize the coefficient sets, we propose an algorithm by using the genetic
algorithm. In the numerical example, we demonstrate the effectiveness of the proposed method. 相似文献
65.
Masayoshi Suehiro Zi-Kui Liu John Ågren 《Metallurgical and Materials Transactions A》1998,29(13):1029-1034
The model for the solute drag effect in phase transformations has been applied to recrystallization, i.e., moving grain boundaries. In this model, the total driving force is dissipated by the interfacial energy, the finite interfacial
mobility, the solute drag in boundaries, and diffusion in the matrix ahead of the interface, of which all are taken into account
consistently. The effects of the Gibbs energy of segregation and the diffusivity of impurity atoms in boundaries were investigated.
The results show that the Gibbs energy of segregation mainly affects the critical composition at which the drastic change
in the boundary velocity appears, and the diffusivity of impurity atoms in boundaries mainly affects the velocity reduced
by the solute drag effect. In other words, the Gibbs energy of segregation and the diffusivity of impurity atoms in boundaries
can be evaluated from experimental data by means of the present model. This model was applied to the Al−Mg system, and the
Gibbs energy of segregation and the diffusivity of Mg in boundaries were evaluated from experimental data. The evaluated Gibbs
energy of segregation agrees with the estimate based on elastic energy considerations. The diffusivity estimated from this
model is smaller than that measured along the grain boundary.
ZI-KUI LIU, formerly with the Department of Materials Science and Engineering, Royal Institute of Technology 相似文献
66.
Seiji Isoda Masaki Tsuji Masayoshi Ohara Akiyoshi Kawaguchi Ken-ichi Katayama 《Polymer》1983,24(9):1155-1161
The crystal structure of β-form poly(p-xylylene) is analysed starting from a high-resolution image of a single crystal of this polymer. The high-resolution image corresponding to the projection of molecules onto the ab-plane along the chain axis shows clearly the mutual position of each molecule in a unit cell. The molecules are aligned wavily in the direction along the a-axis and the rough positions of their centres in a unit cell can be determined from the image. The refinement of the structure is carried out by the usual least-squares method using the intensities of electron and X-ray diffractions. The space group of the β-form is trigonal, P3, and the lattice dimensions are a=2.052 nm, c=0.655 nm and γ=120°. The unit cell contains 16 molecules and one of them is considered to occupy statistically one of three equivalent orientations so as to satisfy the P3 symmetry. 相似文献
67.
68.
69.
S. Itou 《Engineering Fracture Mechanics》1980,13(2):349-356
The problem of determining the transient stress distribution in an infinite elastic medium weakened by two coplanar Griffith cracks is considered. To the surfaces of the cracks, an internal pressure is applied suddenly. The problem is reduced to that of solving dual integral equations in the Laplace transform domain and those are solved by a series-expansion method. The dynamic stress intensity factors are computed numerically. 相似文献
70.