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121.
James Cheng Zechao Shang Hong Cheng Haixun Wang Jeffrey Xu Yu 《The VLDB Journal The International Journal on Very Large Data Bases》2014,23(2):227-252
We study the problem of answering k -hop reachability queries in a directed graph, i.e., whether there exists a directed path of length $k$ , from a source query vertex to a target query vertex in the input graph. The problem of $k$ -hop reachability is a general problem of the classic reachability (where $k=\infty $ ). Existing indexes for processing classic reachability queries, as well as for processing shortest path distance queries, are not applicable or not efficient for processing $k$ -hop reachability queries. We propose an efficient index for processing $k$ -hop reachability queries. Our experimental results on a wide range of real datasets show that our method is efficient and scalable in terms of both index construction and query processing. 相似文献
122.
A new kind of blend film was made by mixing the solutions of collagen, konjac glucommnnan (KGM), and sodium alginate. The structure of the blend film was characterized by FTIR, XRD, atomic absorption spectrophotometer, and SEM, respectively. The effects of weight ratio between the polymers on light transmittance, tensile strength, elongation at break, water permeability, and water absorption of the film were studied. The results showed that there were strong interactions and good compatibility between collagen, KGM, and sodium alginate in the film. The film possesses good mechanical properties. Therefore, it can be applied in biomedicine as a new type of biomaterial. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 2007 相似文献
123.
Helen E. Hermes Henrich Frielinghaus Wim Pyckhout-Hintzen Dieter Richter 《Polymer》2006,47(6):2147-2155
A new model is presented which can describe quantitatively the small angle neutron scattering from montmorillonite-type clay dispersions and polymer-clay nanocomposites. The model is shown to be able to describe well the data from a series of dilute montmorillonite in water dispersions in which the deuterium content of the water phase is varied. The fits combined with information from other techniques suggest strongly that H-D exchange occurs in the montmorillonite-water dispersions. Deviations from Q−2 behaviour often observed experimentally for clay dispersions are convincingly explained by the presence of a small proportion of tactoids. 相似文献
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Xiongwei Qu Shurui Shang Guodong Liu Shengwen Zhang Yan Zhang Liucheng Zhang 《应用聚合物科学杂志》2004,91(3):1685-1697
Blends of poly(styrene‐co‐acylonitrile) (SAN) with ethylene–propylene–diene monomer (EPDM) rubber were investigated. An improved toughness–stiffness balance of the SAN/EPDM blend was obtained when an appropriate amount of acrylonitrile–EPDM–styrene (AES) graft copolymer was added, prepared by grafting EPDM with styrene–acrylonitrile copolymer, and mixed thoroughly with both of the two components of the blend. Morphological observations indicated a finer dispersion of the EPDM particles in the SAN/EPDM/AES blends, and particle size distribution became narrower with increasing amounts of AES. Meanwhile, it was found that the SAN/EPDM blend having a ratio of 82.5/17.5 by weight was more effective in increasing the impact strength than that of the 90/10 blend. From dynamic mechanic analysis of the blends, the glass‐transition temperature of the EPDM‐rich phase increased from ?53.9 to ?46.2°C, even ?32.0°C, for the ratio of 82.5/17.5 blend of SAN/EPDM, whereas that of the SAN‐rich phase decreased from 109.2 to 108.6 and 107.5°C with the additions of 6 and 10% AES copolymer contents, respectively. It was confirmed that AES graft copolymer is an efficient compatibilizer for SAN/EPDM blend. The compatibilizer plays an important role in connecting two phases and improving the stress transfer in the blends. Certain morphological features such as thin filament connecting and even networking of the dispersed rubber phase may contribute to the overall ductility of the high impact strength of the studied blends. Moreover, its potential to induce a brittle–ductile transition of the glassy SAN matrix is considered to explain the toughening mechanism. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 1685–1697, 2004 相似文献
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目的 针对全球大场景渲染中单精度浮点数的低精度导致的图像抖动和撕裂问题,提出了一套完整的解决方法。方法 首先,使用全球四叉树结构来寻找新的坐标原点,避免了现有算法需要频繁切换世界坐标原点的缺点;其次,在新坐标系下进行坐标转换和矩阵转换,解决了像素坐标计算的误差导致的抖动问题;最后,在GPU中使用基于对数的深度计算方式来提高深度的分辨率,解决了深度计算误差导致的Z-Fighting现象。结果 实验结果表明所提方法能很好的解决单精度浮点导致的渲染问题。结论 此方法具有适应性强、实现复杂度低、精度和效率可控等优点。 相似文献
128.
C. D. Evans G. R. List Helen A. Moser J. C. Cowan 《Journal of the American Oil Chemists' Society》1973,50(6):218-222
Commercially prepared and packaged soybean and cottonseed salad oils from several different processors were evaluated periodically
during storage for 12 months. Partially hydrogenated and winterized soybean oils, as well as unhydrogenated soybean salad
oils, were stored in bottles and cans at 78 and 100 F. Control samples of all oils were held at 0 F during the entire test.
Some lots in bottles and cans were packaged under nitrogen to improve storage stability. Agreement was good between organoleptic
and oxidative evaluation of aged oils. After 26 weeks of storage at 100 F, the flavor of partially hydrogenated-winterized
oils packaged under nitrogen showed a minimum loss. These same oils did not exhibit much, if any, reduction in their oxidative
stability as indicated by storage peroxide values (active oxygen method). Soybean oil not protected with nitrogen demonstrated
progressive flavor deterioration at 100 F. After 10 weeks of storage, the deterioration became marked and the flavor score
was below 5. From limited observations, bottled oils appear to have a better stability than oils packaged in screw-cap tin
cans. Hydrogenated oils packaged under nitrogen in cans had good oxidative stability, but some lowering of the flavor score
was observed. Nonhydrogenated soybean oils packaged in tin cans not under nitrogen exhibited the most rapid flavor deterioration
of all lots of oil investigated.
Presented in part at the AOCS meeting, New York, October 1968
ARS, USDA 相似文献
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