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831.
832.
833.
Zhi-Wen Gao Kang Yong Lee You-He Zhou 《Journal of Mechanical Science and Technology》2012,26(2):353-357
In this letter, the shielding or anti-shielding effect is firstly applied to obtain the behavior of two parallel cracks in
a two-dimensional type-II superconducting under electromagnetic force. Fracture analysis is performed by the finite element
method and the magnetic behavior of superconductor is described by the critical state Bean model. The stress intensity factors
at the crack tips can be obtained and discussed for decreasing field after zero-field cooling. The shielding or anti-shielding
effect at the crack tips depend on the distance between two parallel cracks and the crack length. The results indicate that
the shielding effects of the two parallel cracks increase when the distance between the two parallel cracks decreases. It
can be also obtained that the superconductors with shorter cracks has more remarkable shielding effect than those with longer
cracks. 相似文献
834.
Jian Kang Feng Yang Tong Wu Huilin Li Dongming Liu Ya Cao Ming Xiang 《应用聚合物科学杂志》2012,125(4):3076-3083
Two isotactic polypropylene (iPP) samples (PP-A and PP-B) were obtained by utilizing two different heterogeneous Ziegler–Natta catalysts in a given polymerization system. The molecular structure and conformational behavior of the samples were studied. The results of determination of xylene soluble material (XS) and 13C NMR showed that the average isotacticity of the samples were nearly same. However, the results of high-resolution high-temperature 13C NMR (HRHT 13C NMR) and successive self-nucleation and annealing (SSA) fractionation revealed that the amount of high isotacticity of PP-B was lower than that of PP-A, and the amount of relative medium and low isotacticity of PP-B was higher than PP-A, indicating that the stereodefect distribution of PP-B was more uniform than PP-A. The calculation of average meso sequence length from SSA was found to be in good agreement with that calculated from the results of HRHT 13C NMR. Moreover, Fourier transformation infrared was utilized to study the influence of stereodefect distribution on the conformational behavior of iPP. The result suggested that the molecular conformation of the PP-B was more disordered than PP-A, the regularity of molecular structure for PP-B was lower than that of PP-A. The related action mechanism and the influences of which on crystallization behavior were discussed. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012 相似文献
835.
A statically recrystallized Mg-3Al-1Zn alloy was fabricated by low temperature roll heating (140 °C) processes and subsequent
annealing at 250 °C for 5 min. The fabricated sheet, with a grain size of 4.1 m, shows an improved planar anisotropy and higher
elongations to failure at room temperature and 200 °C, compared with those of the sheet fabricated by conventional hot rolling
processes, due to the weak basal texture along with the refined microstructure. 相似文献
836.
The electronic band structure and carrier density of strained armchair graphene nanoribbons (AGNRs) with widths of n =3 m and n =3 m +1 were examined using tight-binding approximation. The current-voltage (I-V) model of uniaxial strained n =3 m AGNRs incorporating quantum confinement effects is also presented in this paper. The derivation originates from energy dispersion throughout the entire Brillouin zone of uniaxial strained AGNRs based on a tight-binding approximation. Our results reveal the modification of the energy bandgap, carrier density, and drain current upon strain. Unlike the two-dimensional graphene, whose bandgap remains near to zero even when a large strain is applied, the bandgap and carrier density of AGNRs are shown to be sensitive to the magnitude of uniaxial strain. Discrepancies between the classical calculation and quantum calculation were also measured. It has been found that as much as 19% of the drive current loss is due to the quantum confinement. These analytical models which agree well with the experimental and numerical results provide physical insights into the characterizations of uniaxial strained AGNRs. 相似文献
837.
Eun-kyung Kang Byung Min Lee Hyun Ah Hwang Ji-Hyun Kim 《Journal of Industrial and Engineering Chemistry》2012,18(4):1366-1369
Fossil fuel reserves are limited and global warming is emerging as a serious problem. To solve these problems, efforts to develop alternative energy sources are underway. In recent years the chemical industry based on the environmentally sound and sustainable biomass has been developing. Algae is regarded as important raw material of biomass. Polysaccharides such as cellulose and galactan obtained from the biomass can be converted to simple mono-saccharides by acid hydrolysis reactions. The formed monosaccharides are analyzed quantitatively and qualitatively by using liquid chromatography, ion chromatography and gas chromatography. By using acids to hydrolyze polysaccharides, monosaccharides can be formed as the structure of close form and/or open form. In this study, analysis methods of monosaccharides formed by acid saccharification are investigated to distinguish between close form and open form. 相似文献
838.
Joo Hee Kim Seok Hyun Nam Catherine W. Rico Mi Young Kang 《International Journal of Food Science & Technology》2012,47(6):1176-1182
The antioxidative and anti‐allergic activities of fresh and aged black garlic extracts were investigated. The garlic samples were extracted with 70% ethanol (v/v) and the total phenolic content was measured. The antioxidant capacity of extracts was assessed by determining the scavenging activities on 1,1‐diphenyl‐2‐picrylhydrazyl and hydroxyl radicals, ferricyanide reducing power, ferrous ion‐chelating ability and inhibitory effect on linoleic acid peroxidation. The anti‐allergic activity of extracts was analysed by measuring their inhibitory effects against β‐hexosaminidase release. The aged black garlic exhibited significantly higher phenolic content and greater antioxidative activity than fresh garlic. Both garlic extracts showed strong antioxidant capacity in a dose‐dependent manner. On the other hand, a considerably higher suppression of β‐hexosaminidase release was found in fresh garlic extract at lower concentration compared with that of the black garlic. Results of this study illustrate that ageing of garlic could enhance its antioxidant capacity, but could decrease its anti‐allergic activity. 相似文献
839.
Chang-Yu Lu Myung-Cheol Roh Seung-Yeon Kang Seong-Whan Lee 《Pattern Analysis & Applications》2012,15(2):175-187
The amount of user created contents has been increasing rapidly and is associated with a serious copyright problem. Automatic logo detection and recognition in videos is a natural and efficient way of overcoming the copyright problem. However, logos have varying characteristics, which make logo detection and recognition very difficult. Moreover, logo transitions between two different logos exist in one video comprising several video contents. This disrupts the automatic logo detection and recognition. Therefore, in order to improve logo detection, it is necessary to take into account the logo transitions explicitly. This paper proposes an accurate logo transition detection method for recognizing logos in digital video contents. The proposed method accurately segments a video according to logo and efficiently recognizes various types of logos. The experimental results demonstrate the effectiveness of the proposed method for logo detection and video segmentation according to logo. 相似文献
840.
Yuhao Yang Enzhou Liu Hongzhe Dai Limin Kang Huitong Wu Jun Fan Xiaoyun Hu Hanchen Liu 《International Journal of Hydrogen Energy》2014
TiO2-graphene (P25-GR, PG) nanocomposite was fabricated with P25 and graphite oxide through a hydrothermal method, and then Ag nanoparticles (Ag NPs) was assembled in P25-GR (Ag-P25-GR, APG) under microwave-assisted chemical reduction. The prepared samples were characterized by X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscope (SEM), transmission electron microscopy (TEM), photoluminescence spectrum (PL), UV–vis absorption spectrum (UV–vis) and Raman spectrum, respectively. The results showed that Ag NPs were well dispersed on the surface of PG with metallic state. The ternary Ag-P25-GR (APG) nanocomposites possessed the extended light absorption range and more efficient charge separation properties compared to binary P25-GR (PG). Methylene blue photodegradation experiment proved that surface plasmon resonance (SPR) phenomenon had an effect on photoreaction efficiency. The corresponding hydrogen evolution rate of APG prepared with 0.002 M AgNO3 solution was 7.6 times than pure P25 and 2.7 times than PG in the test condition. The improved photocatalytic performance can be attributed to the presence of GR and SPR effect, leading to the longer lifetime of photo-generated electron–hole pairs and faster interfacial charge transfer rate. This work indicates that the photoactivity of ternary GR-based nanocomposites is superior to the binary one. We expected our work could give a new train of thought on exploration of GR-based nanocomposites. 相似文献