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81.
Polyethylene reactor powders prepared under different conditions were characterized using transmission electron microscopy, 1H nuclear magnetic resonance and X-ray diffraction techniques. The molecular weight of the polyethylene reactor powders was around 1 × 105. A unique domain morphology, quite different from the usual melt- or solution-crystallized lamellar structure, was observed, independent of polymerization temperature (Tpoly). Annealing of reactor powders caused the aggregation of these crystalline domains, due to the significant molecular motion of the amorphous chains, before melting. The critical temperature was 20 °C higher than each Tpoly, and corresponded to the temperature at the active catalyst site producing the chain growth. The morphologies of powders prepared at the lower Tpoly contained smaller crystals that exhibited a constrained monoclinic form. In contrast, only usual orthorhombic crystals of larger size were found within the powder prepared at the higher Tpoly. These results suggest that the competitive processes of chain propagation and crystal growth upon polymerization may lead to unique variations of the crystalline and amorphous phases, but with similar intermediate components in the phase that connects them. 相似文献
82.
Yuki Matsushita Junko Taniguchi Ryo Toda Hiroki Ikegami Taku Matsushita Mitsunori Hieda Nobuo Wada 《Journal of Low Temperature Physics》2008,150(3-4):342-346
We have studied heat capacities of 4He adsorbed in straight nanopores 1.8, 2.2, and 2.8 nm in diameter. Heat capacities of the 4He fluid film on the solid layer at 0.08–0.4 K show power laws close to T in 1.8 nm pores, close to T
2 in 2.8 nm pores, and a crossover from T to T
2 with increasing temperature in 2.2 nm pores. These heat capacities are explained by a model assuming a phonon dispersion
with continuous one-dimensional (1D) states in the axial direction and discrete energy levels in the azimuthal direction.
By fitting experimental data to the model, the phonon velocity along the pore axis and the energy gap for propagation in the
cross section are derived. At temperatures sufficiently lower than the energy gap, where the thermal wave length of phonons
is much longer than the effective pore diameter, the 4He fluid films show a T-linear heat capacity of 1D phonons propagating only along the pore axis. At higher temperatures, a 1D-2D crossover of phonons
occurs.
相似文献
83.
Shingo Hasegawa Shuji Isobe Hiroki Shizuya Katsuhiro Tashiro 《International Journal of Information Security》2009,8(5):347-355
The notion of pseudo-free group was first introduced by Hohenberger (Master’s thesis, EECS Dept., MIT, 2003). Rivest (TCC
2004. LNCS 2951, 505–521, 2004) formalized it and showed that several standard cryptographic assumptions hold on pseudo-free groups, such
as the RSA assumption, the strong RSA assumption and the discrete logarithm assumption. Rivest (TCC 2004. LNCS 2951, 505–521, 2004) also proposed some variations of pseudo-free group, and those were formalized by Hirano and Tanaka (Research
Reports, Series C: Computer Science, C-239, Tokyo Institute of Technology, 2007). In this paper, we study the relationships
among such variations of pseudo-free group. We show that the pseudo-freeness implies the weak pseudo-freeness, and that the
pseudo-freeness is equivalent to the pseudo-freeness with generalized exponential expressions. We also show that the computational
Diffie-Hellman assumption holds on pseudo-free groups in a slightly varied form. 相似文献
84.
Independent component analysis (ICA) is a technique of transforming observation signals into their unknown independent components; hence, ICA has often been applied to blind signal separation problems. In this application, it is expected that the obtained independent components extract essential information of independent signal sources from input data in an unsupervised fashion. Based on such characteristics, ICA is currently utilized as a feature extraction method for images and sounds for recognition purposes. However, since ICA is an unsupervised learning, the obtained independent components are not always useful in recognition. To overcome this problem, we propose a supervised approach to ICA using category information. The proposed method is implemented in a conventional three‐layered neural network, but its objective function to be minimized is defined not only for the output layer but also for the hidden layer. The objective function consists of the following two terms: one evaluates the kurtosis of hidden unit outputs and the other evaluates the error between output signals and their teacher signals. The experiments are performed using several standard datasets to evaluate performance of the proposed algorithm. It is confirmed that a higher recognition accuracy is attained by the proposed method as compared with a conventional ICA algorithm. © 2007 Wiley Periodicals, Inc. Electr Eng Jpn, 161(2): 25–32, 2007; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20522 相似文献
85.
Tomohito Hamazaki Shigeki Sawazaki Tetsuro Nagasawa Yoko Nagao Yuko Kanagawa Kazunaga Yazawa 《Lipids》1999,34(1):S33-S37
The purpose of the present research was to clarify the effect of docosahexaenoic acid (DHA) intake on behavior and plasma catecholamines (CA). In Study 1, 42 students took either DHA-rich oil capsules containing 1.5–1.8 g DHA/d or control oil capsules containing 97% soybean oil plus 3% of another fish oil for 3 mon in a double-blind fashion. They took a psychological test (PF Study) at the start and end of the study. This study started at the end of summer vacation and ended just before the final exams. In the control group, external aggression (aggression against others) in PF Study was significantly increased at the end of the study as compared with that measured at the start (+8.9%), whereas it was not significantly changed in the DHA group (?1.0%). In a similar double-blind study (Study 2), we measured external aggression under nonstressful conditions. External aggression slightly decreased in the control group, whereas there were no significant changes in the DHA group. In Study 3 with 14 students, plasma CA were measured at the start and end of capsule administration period of 2 mon. Subjects were under continuous stress of the final exams that lasted throughout the whole study period. The ratio of plasma epinephrine to norepinephrine concentrations was significantly increased in the DHA group (78%), whereas it stayed at the same level in the control group. In Study 4, mice were fed either DHA-deficient diet or -sufficient diet for 4 wk, and their rearing frequency (an anxiety index) was measured. In the DHA-sufficient group, the rearing frequency was significantly less than in the other group. These effects of DHA intake may be applied to people in an attempt to ameliorate stress-related diseases. 相似文献
86.
87.
Hitoshi Ohta Susumu Okubo Shojiro Kimura Tsuyoshi Tanaka Hikomitsu Kikuchi Hiroshi Nagasawa 《Journal of Infrared, Millimeter and Terahertz Waves》2001,22(3):387-391
Developments of the high field ESR system in Kobe University is presented. Using Gunn oscillators and backward traveling oscillators (BWO), we can cover the frequency region from 30 to 1183.6 GHz with the use of InSb detector. Pulsed magnetic field up to 30 T is available and we are now trying to extend the field up to 40 T. Temperature range is from 1.8 to 300 K. Using this system, we studied S=1/2 ladder like system Cu2(C5H12N2)2Cl4, and found a new magnetic transition at 10.1 T at 1.8 K. The temperature dependence of ESR in Cu2(C5H12N2)2CI4 shows g-shift below 8 K which corresponds to the maximum of the magnetic susceptibility. The g-shift below 8 K suggests the increase of the quantum fluctuation in the system, and the role of the quantum fluctuation in Cu2(C5H12N2)2CI4 is discussed. 相似文献
88.
Blind deconvolution is a method of recovering transmitted signals from only received signals. The probability distribution method is one of the blind deconvolution methods. This method has two problems: it has slower convergence and its reliability is lower. In this paper, we propose a new algorithm for solving these two problems. The proposed algorithm is as follows. (1) It is based on the adaptive processing with each sample. (2) Kurtosis is adaptively estimated by recovered signals with each sample. (3) Cost function is decided by kurtosis. (4) Transmitted signals are recovered by received signals using decided cost function on the sample time. We confirm the validity of the new algorithm by computer simulation. © 2007 Wiley Periodicals, Inc. Electr Eng Jpn, 162(1): 56–65, 2008; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20317 相似文献
89.
Poly(9,10-dihydrophenanthrene-2,7-diyl)s with -OSi(R)2(R′) groups at the 9,10-positions were synthesized by dehalogenative polycondensation of the corresponding monomers by using a zerovalent nickel complex. They showed number average molecular weights (Mn's) of 9800-69,000 and high quantum yields (62%-quantitative) in photoluminescence. Palladium catalyzed copolymerization of 2,7-dibromo-9,10-dihydrophenanthrene having -OCH3 or -OSi(R)2(R′) groups at the 9,10-positions with diethynyl- or diboronic-aromatic compounds also gave photoluminescent polymers with high quantum yields. 相似文献
90.
Ooki Kurihara Takashi Tsuchida Genki Takahashi Gyeong-o Kang Hiroki Murakami 《Soils and Foundations》2018,58(5):1173-1186
Great amounts of soil and waste contaminated with radioactive cesium have been generated due to the decontamination work after the Fukushima Daiichi Nuclear Power Plant accident. The aim of this study is to develop a sealing geomaterial for use at the disposal facilities of the soil and waste constructed in the maritime environment. The geomaterial consists of marine clay, bentonite, and zeolite. The hydraulic conductivity and cesium-adsorption performance of the geomaterial were examined through laboratory tests with different proportions of bentonite and zeolite added to marine clay. It was concluded that the hydraulic conductivity could be reduced to the required level by increasing the amount of bentonite and that the cesium-adsorption capacity could be enhanced by increasing the amount of zeolite. 相似文献