国际视野下的国家风景道体系建设：美国、 德国和挪威的实践

风景道体系建设是国家旅游与交通产业融合发展的 举措，对推动区域景观服务增值、带动乡村及偏远地区可持续 发展具有重要意义。当前研究存在风景道历史不清晰、概念与 形式不明确、建设与管理经验不明朗等情况。从国际视野出 发，厘清了风景道发展脉络，并以美国、德国和挪威为例，讨 论了国际范围内风景道的概念与形式，挖掘了不同国家风景道 沿线景观的视域特征、场景特征及吸引物特征，梳理了各国风 景道质量管理的制度、景观形象的塑造与推广，总结了国家风 景道建设与管理的国际经验，为当前风景道体系建设的关键任 务提供参考。     

Crack tip shielding and anti-shielding effects of parallel cracks for a superconductor slab under an electromagnetic force

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.     

Investigation of the stereodefect distribution and conformational behavior of isotactic polypropylene polymerized with different Ziegler–Natta catalysts

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     

Texture development and deformation behavior of a statically recrystallized Mg-Al-Zn alloy sheet

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.     

Analytical performance of 3?m and 3?m +1 armchair graphene nanoribbons under uniaxial strain

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.     

Analysis of mono-sugars obtained by acid hydrolysis of algae-based polysaccharides

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.     

A comparative study on the antioxidative and anti‐allergic activities of fresh and aged black garlic extracts

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.     

Automatic logo transition detection in digital video contents

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.