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91.
Rubber bearings used in bridges are exposed to the air and easily attacked by oxygen, even at room temperature, and heat, light, dynamic strain, and liquids. It is usually known that the degradation of polymers often occurs as a nonuniform or heterogeneous process because aged rubber will prevent deterioration from progressing into the inner rubber bearing. Thermal oxidation tests were carried out on natural rubber (NR) blocks at different elevated temperatures using the modulus profiling method. The development of the heterogeneous property profiles in aged rubber bearings is revealed. The NR blocks display the features of a diffusion-limited oxidation and the properties change most significantly at the surface. However, in the interior region beyond the critical depth, NR does not change. The property variations at the block surface and the interior are quantitatively examined, based on which, the relations are clarified among property variation, temperature, aging time, and relative position inside a rubber bearing. An appropriate aging model is established, which is able to predict the aging characteristics in NR bearing. 相似文献
92.
The low molecular weight component of gelatin has been investigated by determination of the molecular weight distribution of the sol fraction from hardened gelatin films. The hardeners used were formaldehyde and mucochloric acid. Different hardening conditions and gelatin types were studied. It was observed that a couple of weeks were needed to reach a stable level of hardening. Acid- processed gelatins exhibited higher reactivity than lime-processed gelatins. The results indicate that the method seems to be effective as an evaluation of gelatin hardening. 相似文献
93.
Yoshihiro Itoh Fumiya Sahara Kaori Ozaki Ryo Akasaka Akira Teramoto 《Polymer Bulletin》2011,67(8):1455-1462
Emulsion polymerizations of several vinyl monomers, styrene, methyl methacrylate, butyl methacrylate, butyl acrylate, and
vinyl acetate, in water using alkali–hydrolysable cationic surfactants with a betaine ester group (1-alkoxycarbonylmethyl)trimethylammonium
chlorides, as emulsifiers were carried out and properties of the resulting latices and the polymers recovered by hydrolysis
and salting out were investigated. There were little influences of the surfactants and monomers used here on the polymerizations,
forming stable and monodisperse latices with a mean diameter of ca. 70 nm and giving a high molecular weight of polymers at
high yields. All polymers were precipitated and recovered by adding a small amount of sodium hydroxide into the latex solutions
contained little amount of ionic species. Solvent-cast films of the polymers were found to have surfaces as hydrophobic as
those for the corresponding pure polymers prepared by bulk polymerization. 相似文献
94.
Akihiro Odaka Ikuya Sato Hideki Ohguchi Yasuhiro Tamai Hironori Mine Jun‐Ichi Itoh 《Electrical Engineering in Japan》2009,166(4):88-96
In this paper, a novel control method for a matrix converter is proposed. The proposed method is a PAM (Pulse Amplitude Modulation) control method based on a virtual AC/DC/AC conversion method. Output voltage amplitude is controlled by controlling a virtual DC link voltage with a virtual rectifier. Output frequency is controlled by a virtual inverter. First, the proposed method is explained. Next, the validity of the proposed method is confirmed through simulation and experiment using a 750‐W prototype matrix converter. Moreover, various characteristics of the proposed method and conventional virtual AC/DC/AC method are compared through experiment. As a result of the experiment, it has been understood that total harmonic distortion of output current and common‐mode voltage can be reduced compared with the case of using a conventional virtual AC/DC/AC conversion method. © 2008 Wiley Periodicals, Inc. Electr Eng Jpn, 166(4): 88–96, 2009; Published online in Wiley InterScience ( www.interscience. wiley.com ). DOI 10.1002/eej.20601 相似文献
95.
Nakao Y. Itoh H. Hoshino S. Sakai Y. Tagashira H. 《Dielectrics and Electrical Insulation, IEEE Transactions on》1994,1(3):383-389
Prebreakdown phenomena in n-hexane are observed in detail for positive and negative polarities by using simultaneously a high speed schlieren technique and an LED current measuring system, when an impulse voltage (1.1/225 μs) is applied to a point-to-plane electrode gap. Furthermore, the effects of several additives on the streamer propagation are investigated. Especially the effects of electron-trapping additives on negative streamer propagation and of low ionization potential additives on the positive streamer propagation, are examined, as is a correlation between the shape and the propagation velocity of the streamers 相似文献
96.
Sarukura N. Dubinskii M.A. Zhenlin Liu Semashko V.V. Naumov A.K. Korableva S.L. Abdulsabirov R.Y. Edamatsu K. Suzuki Y. Itoh T. Segawa Y. 《IEEE journal of selected topics in quantum electronics》1995,1(3):792-804
New possibilities have been investigated for recently developed solid-state tunable ultraviolet (UV) laser materials such as Ce3+ ion-activated LuLiF4 (LLF) and LiCaAlF6 (LiCAF). With their broad-gain width, demonstrated reliability, and high efficiency, they are attractive for ultrashort pulse generation and amplification. To prove that, we have demonstrated UV picosecond-pulse amplification using Ce:LLF. For such new laser materials, we proposed a passive self-injection seeding scheme for the direct generation of short-pulse trains, which does not require CW operation capability or an external short-pulse seeding laser, Using this simple scheme, a UV sub-nanosecond pulse train is directly and passively generated from Ce:LLF pumped by a standard 10-ns KrF excimer laser, and Ce:LiCAF pumped by the fourth harmonic of a conventional 10-ns Q-switched Nd:YAG laser 相似文献
97.
Fabrication of optics by use of plasma chemical vaporization machining with a pipe electrode 总被引:1,自引:0,他引:1
Takino H Shibata N Itoh H Kobayashi T Yamamura K Sano Y Mori Y 《Applied optics》2002,41(19):3971-3977
We figure optical surfaces by plasma chemical vaporization machining (CVM) with a pipe electrode, in which an rf plasma generated at the electrode tip under approximately atmospheric pressure moves over the surfaces. We propose a shaping method in which the movement of plasma on the surfaces can be determined. Flat and aspheric surfaces are successfully figured with the desired peak-to-valley shape accuracy of 0.1 microm. The root-mean-square roughness of the resultant surfaces is at the subnanometer level. These results confirm that the plasma CVM and the shaping method have the capability to fabricate optics with high accuracy. 相似文献
98.
We demonstrate an integrated-optic encoder/decoder for time-spreading/wavelength-hopping optical code division multiple access. It is composed of a wavelength multi/demultiplexer and variable delay lines fabricated by using silica-based planar lightwave circuit technology. We evaluated the device characteristics, including those of the key components and the encoding/decoding operation, and confirmed its flexible code assignment ability and good auto/cross correlations. We then tested the performance of the encoder/decoder by undertaking bit error rate measurements with 10-Gb/s pseudorandom binary sequence signals and confirmed its applicability to optical layer multicast routing and its ability to compensate for bit skew caused by fiber chromatic dispersion. 相似文献
99.
Hirofumi Hirayama Toshihiro Itoh Yoshihiko Nakaki Takahiko Yoshida 《Artificial Life and Robotics》2005,9(3):144-160
A mathematical method is introduced to characterize the electrokinetic behavior (electrophoresis) of a biomolecular particle which passes through a specific channel pore on an excitable biological membrane. The basic approach was first proposed by Booth (1950). The system was described by an equation of continuity and an equation of motion in which the driving force involves the diffusion effect, the hydrostatic pressure, and the electrostatic potential. By assuming linear relations between the velocity and the applied electrical field, solutions for the potential, pressure, and velocity were given by a series expansion of the charges on the particle. To examine the influence of ions surrounding the particle and forming an ionic cloud, the Debye–Huckel parameter was introduced. As the thickness of the double layer around the particle increased, the potential, velocity, pressure, and viscosity were changed significantly. The maximum influence was obtained when the radius of the particle became equal to the thickness of the double layer. Although this theory is valid for a charged, spherical, nonconducting particle only, the method is available for evaluating the kinetic behavior of a biomolecule that passes through a channel pore on a cellular membrane.This work was presented, in part, at the 8th International Symposium on Artificial Life and Robotics, Oita, Japan, January 24–26, 2003 相似文献
100.
This paper proposes a new, efficient algorithm for extracting similar sections between two time sequence data sets. The algorithm,
called Relay Continuous Dynamic Programming (Relay CDP), realizes fast matching between arbitrary sections in the reference
pattern and the input pattern and enables the extraction of similar sections in a frame synchronous manner. In addition, Relay
CDP is extended to two types of applications that handle spoken documents. The first application is the extraction of repeated
utterances in a presentation or a news speech because repeated utterances are assumed to be important parts of the speech.
These repeated utterances can be regarded as labels for information retrieval. The second application is flexible spoken document
retrieval. A phonetic model is introduced to cope with the speech of different speakers. The new algorithm allows a user to
query by natural utterance and searches spoken documents for any partial matches to the query utterance. We present herein
a detailed explanation of Relay CDP and the experimental results for the extraction of similar sections and report results
for two applications using Relay CDP.
Yoshiaki Itoh has been an associate professor in the Faculty of Software and Information Science at Iwate Prefectural University, Iwate,
Japan, since 2001. He received the B.E. degree, M.E. degree, and Dr. Eng. from Tokyo University, Tokyo, in 1987, 1989, and
1999, respectively. From 1989 to 2001 he was a researcher and a staff member of Kawasaki Steel Corporation, Tokyo and Okayama.
From 1992 to 1994 he transferred as a researcher to Real World Computing Partnership, Tsukuba, Japan. Dr. Itoh's research
interests include spoken document processing without recognition, audio and video retrieval, and real-time human communication
systems. He is a member of ISCA, Acoustical Society of Japan, Institute of Electronics, Information and Communication Engineers,
Information Processing Society of Japan, and Japan Society of Artificial Intelligence.
Kazuyo Tanaka has been a professor at the University of Tsukuba, Tsukuba, Japan, since 2002. He received the B.E. degree from Yokohama
National University, Yokohama, Japan, in 1970, and the Dr. Eng. degree from Tohoku University, Sendai, Japan, in 1984. From
1971 to 2002 he was research officer of Electrotechnical Laboratory (ETL), Tsukuba, Japan, and the National Institute of Advanced
Science and Technology (AIST), Tsukuba, Japan, where he was working on speech analysis, synthesis, recognition, and understanding,
and also served as chief of the speech processing section. His current interests include digital signal processing, spoken
document processing, and human information processing. He is a member of IEEE, ISCA, Acoustical Society of Japan, Institute
of Electronics, Information and Communication Engineers, and Japan Society of Artificial Intelligence.
Shi-Wook Lee received the B.E. degree and M.E. degree from Yeungnam University, Korea and Ph.D. degree from the University of Tokyo in
1995, 1997, and 2001, respectively. Since 2001 he has been working in the Research Group of Speech and Auditory Signal Processing,
the National Institute of Advanced Science and Technology (AIST), Tsukuba, Japan, as a postdoctoral fellow. His research interests
include spoken document processing, speech recognition, and understanding. 相似文献