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排序方式: 共有689条查询结果,搜索用时 31 毫秒
71.
72.
Xianglan Li Jing Ma Yunjun Yao Shunlin Liang Guangbin Zhang Hua Xu Kazuyuki Yagi 《Nutrient Cycling in Agroecosystems》2014,100(1):65-76
Straw application and midseason drainage play role in controlling methane (CH4) and nitrous oxide (N2O) emissions from rice paddy fields, but little information is available on their integrative effect on CH4 and N2O emissions. A two-year field experiment was conducted to study the combined effect of timing and duration of midseason aeration and wheat straw incorporation on mitigation of global warming potential (GWP) of CH4 and N2O emissions from irrigated lowland rice paddy fields. Results showed that incorporation of wheat straw increased CH4 by a factor of 5–9 under various water regimes, but simultaneously decreased N2O emission by 19–42 % during the rice growing season. Without straw incorporation, prolonged aeration significantly reduced the net 100-year GWP of CH4 and N2O emissions by 6 %, but also decreased rice production when compared with normal aeration. With straw incorporation, the lowest GWP was found by early aeration, which reduced GWP by 7 and 20 % in 2007 and 2008, respectively. Estimation of net GWPs of CH4 and N2O emissions indicated that early midseason drainage with straw incorporation offered the potential to mitigate CH4 and N2O emissions from irrigated lowland rice paddies in China. 相似文献
73.
Tooru Kitagawa Kazuyuki Yabuki Andrew C. Wright Robert. J. Young 《Journal of Materials Science》2014,49(18):6467-6474
A detailed morphological study of the microstructure of poly(p-phenylene benzobisoxazole) (PBO) fibres (HM and HM+) and a polypyridobisimidazole (PIPD) (HT) fibre has been undertaken using transmission electron microscopy. Both PBO and PIPD fibres are composed of rigid-rod polymers having p-phenylene rings in the molecular backbone and show high modulus (280–360 GPa) and high strength (4–6 GPa). It is found that the PBO HM+ fibre has the highest degree of molecular orientation of the three fibres and the longest crystal length along the fibre axis, while the PIPD fibre shows a lower degree of orientation and a shorter crystal length than the PBO fibres. To understand the effect of crystalline size and fine structure of the fibres upon mechanical properties, dark-field and high-resolution lattice images were obtained and analysed in detail. 相似文献
74.
Kazuyuki Yagi Yukito Ebisu Joichi Sugimura Seiji Kajita Toshihide Ohmori Atsushi Suzuki 《Tribology Letters》2011,43(3):361-368
In this study, a direct observation of a point contact area was conducted to understand the scuffing phenomenon. The contact
area was produced between a rotating sapphire disc and a stationary steel ball and it was lubricated using n-hexadecane. The image detected by a colour digital CCD camera, load, and friction were synchronously recorded by a computer
during the test. It was found that wear debris produced in the contact area played an important role in the wear process,
which includes running-in and scuffing. In the test, debris particles accumulated in the inlet zone, and some particles entered
the contact area to cause abrasive wear of the ball surface, even in the light-load stages. During the running-in process,
the abrasive wear by debris particles changed the conformity between the sliding surfaces. In the high-load stage, just before
the occurrence of scuffing, the whole contact area was flattened at once. When scuffing occurred, the contact area suddenly
expanded. The conformity of the contact area was dramatically changed during its expansion. The flattening of the whole contact
area and dramatic expansion with changing the conformity seemed to play important roles in scuffing. 相似文献
75.
Mesoporous silica coated titania exhibited a substrate selective photocatalytic reaction; 4-nonylphenol and phenol were decomposed while nonane was not decomposed by the UV irradiation to their aqueous mixture. 相似文献
76.
Mitsuru Uesaka Takuya NatsuiKiwoo Lee Katsuhiro DobashiTomohiko Yamamoto Takeshi FujiwaraHaito Zhu Kazuyuki DemachiEiji Tanabe Masashi YamamotoNaoki Nakamura Joichi KusanoToshiyasu Higo Shigeki FukudaMitsuhiro Yoshida Shuji Matsumoto 《Nuclear instruments & methods in physics research. Section A, Accelerators, spectrometers, detectors and associated equipment》2011,657(1):82-87
We are developing compact X-band linac X-ray sources for nondestructive evaluation and medicine. First, we develop a portable X-ray system by a 950 keV 9.4 GHz X-band linac to realize on-site inspection. We use a low power (250 kW) magnetron as an RF source for compactness of the whole system. Since the RF power source is quite small and the stored energy in the structure is also small, we faced the problem of beam loading and current/RF-power oscillation. We are analyzing the problem by the circuit model. We plan to use this system for erosion inspection of metal pipes of petrochemical complex. By adopting a side-coupling cavity design to avoid the oscillation, we have developed 6 MeV X-band (9.3 GHz) linac for pinpoint dynamic tracking cancer therapy. Furthermore, we are manufacturing 3.95 MeV X-band (9.3 GHz) linac X-ray source with flexible waveguides for on-site bridge inspection. Updated results and situations are presented. 相似文献
77.
Hiroyuki Mori Yoshinori Sakatani Tatsurou Fujino Kazuyuki Numa 《Electrical Engineering in Japan》2006,156(2):43-51
In this paper, a new efficient feature extraction method is proposed to handle the one‐step‐ahead daily maximum load forecasting. In recent years, power systems become more complicated under the deregulated and competitive environment. As a result, it is not easy to understand the cause and effect of short‐term load forecasting with a bunch of data. This paper analyzes load data from the standpoint of data mining. By it we mean a technique that finds out rules or knowledge through large database. As a data mining method for load forecasting, this paper focuses on the regression tree that handles continuous variables and expresses a knowledge rule as if‐then rules. Investigating the variable importance of the regression tree gives information on the transition of the load forecasting models. This paper proposes a feature extraction method for examining the variable importance. The proposed method allows to classify the transition of the variable importance through actual data. © 2006 Wiley Periodicals, Inc. Electr Eng Jpn, 156(2): 43–51, 2006; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/eej.20104 相似文献
78.
The interaction of the shock reflected at a secondary diaphragm with the primary contact in six cases, i.e. the strengths and shapes of the contact surface are different, were explored by numerical study. The influences of the strength and shape of the contact on the developing wave pattern and the quality of the test gas are illustrated by many kinds of figures (e.g. the time-distance diagrams of the acoustic impedance contours on the axis, the acoustic impedance contours, and the time histories of pilot and static pressures). 相似文献
79.
P Verdier-Pinard JY Lai HD Yoo J Yu B Marquez DG Nagle M Nambu JD White JR Falck WH Gerwick BW Day E Hamel 《Canadian Metallurgical Quarterly》1998,53(1):62-76
Originally purified as a major lipid component of a strain of the cyanobacterium Lyngbya majuscula isolated in Cura?ao, curacin A is a potent inhibitor of cell growth and mitosis, binding rapidly and tightly at the colchicine site of tubulin. Because its molecular structure differs so greatly from that of colchicine and other colchicine site inhibitors, we prepared a series of curacin A analogs to determine the important structural features of the molecule. These modifications include reduction and E-to-Z transitions of the olefinic bonds in the 14-carbon side chain of the molecule; disruption of and configurational changes in the cyclopropyl moiety; disruption, oxidation, and configurational reversal in the thiazoline moiety; configurational reversal and substituent modifications at C13; and demethylation at C10. Inhibitory effects on tubulin assembly, the binding of colchicine to tubulin, and the growth of MCF-7 human breast carcinoma cells were examined. The most important portions of curacin A required for its interaction with tubulin seem to be the thiazoline ring and the side chain at least through C4, the portion of the side chain including the C9-C10 olefinic bond, and the C10 methyl group. Only two modifications totally eliminated the tubulin-drug interaction. The inactive compounds were a segment containing most of the side chain, including its two substituents, and analogs in which the methyl group at the C13 oxygen atom was replaced by a benzoate residue. Antiproliferative activity comparable with that observed with curacin A was only reproduced in compounds that were potent inhibitors of the binding of colchicine to tubulin. Molecular modeling and quantitative structure-activity relationship studies demonstrated that most active analogs overlapped extensively with curacin A but failed to provide an explanation for the apparent structural analogy between curacin A and colchicine. 相似文献
80.
Kazuyuki Wada Shigetaka Takagi Nobuo Fujii 《Analog Integrated Circuits and Signal Processing》1998,16(3):225-238
This paper proposes an automatic tuning system to adjust frequency characteristics of integrated continuous-time filters especially at high frequencies. Frequency characteristic deterioration of a filter using integrators with electrically controllable unity-gain frequencies can be easily evaluated and compensated even when they are affected by deviations of element values and parasitic elements. The compensation requires detection of both frequency and excess phase shifts of the integrators. Their two values are electrically detected by two detection systems usually used in the conventional frequency tuning system. The proposed system is stable, simple and easy to be implemented on an integrated circuit. As an example a 4th-order biquad bandpass filter with 10 MHz center frequency, 2 MHz passband width, and 0.5 dB passband ripples is designed using a bipolar process. Simulation results by SPICE show the effectiveness of the proposed system. 相似文献