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991.
992.
Tae Woo Kim Hana Yoo In Young Kim Hyung‐Wook Ha Ah Reum Han Jong‐San Chang Ji Sun Lee Seong‐Ju Hwang 《Advanced functional materials》2011,21(12):2301-2310
Manganese oxide nanocrystals are combined with aluminum oxide nanocrystals to improve their crystallinity via calcination without a significant increase of crystal size. A nanocomposite, consisting of two metal oxides, can be synthesized by the reaction between permanganate anions and aluminum oxyhydroxide keggin cations. The as‐prepared manganese oxide–aluminum oxide nanocomposite is X‐ray amorphous whereas heat‐treatment gives rise to the crystallization of an α‐MnO2 phase at 600 °C and Mn3O4/Mn2O3 and γ‐Al2O3 phases at 800 °C. Electron microscopy and N2 adsorption‐desorption‐isotherm analysis clearly demonstrate that the as‐prepared nanocomposite is composed of a porous assembly of monodisperse primary particles with a size of ~20 nm and a surface area of >410 m2 g?1. Of particular interest is that the small particle size of the as‐prepared nanocomposite is well‐maintained up to 600 °C, a result of the prevention of the growth of manganate grains through nanoscale mixing with alumina grains. The calcined nanocomposite shows very‐high catalytic activity for the oxidation of cyclohexene with an extremely high conversion efficiency of >95% within 15 min. The present results show that the improvement of the crystallinity without significant crystal growth is very crucial for optimizing the catalytic activity of manganese oxide nanocrystals. 相似文献
993.
994.
Phenolic novolak chemistry, the basis of coating and curing processes employed in resin-coated sand technology, has been studied with differential scanning (calorimetry), degree of cross-linking, gas evolution, and infra-red spectrum testing methods. Various thermal properties of phenolic resin during heating at different temperatures have been obtained. It is suggested that the methods employed in this paper could be used to optimise hot-coating and curing processes associated with Croning shell sand. 相似文献
995.
996.
Sets and bags are closely related structures and have been studied in relational databases. A bag is different from a set
in that it is sensitive to the number of times an element occurs while a set is not. In this paper, we introduce the concept
of web bag in the context of a web warehouse called Whoweda (Warehouse
Of Weda Data) which we are currently building. Informally, a web bag is a web table which allows multiple occurrences of identical web tuples. Web bag helps to discover useful knowledge from a web table such as visible documents (or web sites), luminous documents and luminous paths. In this paper, we perform a cost-benefit analysis with respect to storage, transmission and operational cost of web bags
and discussed issues and implication of materializing web bags as opposed to web tables containing distinct web tuples. We
have computed analytically the upper and lower bounds for the parameters which affect the cost of materializing web bags.
This revised version was published online in August 2006 with corrections to the Cover Date. 相似文献
997.
Cross layer handover schemes are expected to provide seamless services to users on the move. To achieve this goal, a link
layer must timely trigger handover protocols of upper layers so that they can finish necessary handover procedures before
current wireless link terminates. Therefore, a mobile node needs an appropriate model to predict impending handover to generate
link layer triggers in time. In this paper, we propose a mobility model that does not assume any radio propagation environments
and movement patterns of a mobile node. Through statistical analysis of the received signal strength index (RSSI) datasets
measured in various radio propagation environments, we validate that an adaptive autoregressive process can be used as a handover
prediction model. With the proposed model, we also propose a link layer triggering scheme. Since the prediction process inevitably
introduces errors, we devise a statistical compensation method to initiate link layer triggers in a timely manner considering
the given handover signaling delay bound. Simulation results show that the error compensation method can significantly decrease
the rate of late link layer triggers with the reasonable increase in the false alarm rate. 相似文献
998.
999.
J. R. Cho D. Y. Lee W. S. Yoo O. K. Lim 《The International Journal of Advanced Manufacturing Technology》2013,66(1-4):71-81
The bolt–flange fitting and detaching processes are numerically investigated by the updated Lagrangian elastoplastic finite element analysis. The elastoplastic behavior of the flange is modeled by the power-law plastic model with the isotropic strain hardening, while assuming the bolt to be rigid by virtue of the big difference in the material stiffness between bolt and flange. Through the parametric numerical analyses of the bolt–flange fitting and detaching processes with respect to the shape of the bolt cross-section, the characteristics of the bolt fitting and fastening forces are investigated. The validity of the simplified 2-D axisymmetric finite element model is examined through the comparison with the numerical results obtained by 3-D full finite element model. As well, the effects of the bolt petal number on these forces are investigated, and the experiment is performed to verify the numerical simulation. 相似文献
1000.
Relationship of Carcass Weight to Muscle Fiber Characteristics and Pork Quality of Crossbred (Korean Native Black Pig × Landrace) F2 Pigs 总被引:1,自引:0,他引:1
Gap-Don Kim Byeong-Woo Kim Jin-Yeon Jeong Sun-Jin Hur In-Chul Cho Hyun-Tae Lim Seon-Tea Joo 《Food and Bioprocess Technology》2013,6(2):522-529
A total of 168 carcasses of crossbred (Korean native black pig × Landrace) F2 pigs were divided into four carcass weight groups (A, 70–79 kg; B, 80–89 kg; C, 90–99 kg; D, 100–109 kg). The influence of carcass weight on muscle fiber characteristics and meat quality traits of pork, from the longissimus dorsi, were investigated. Carcass traits such as loin-eye area and back-fat thickness were found to increase with increasing carcass weight. Fat content, sarcomere length, drip loss, and meat color values (L*, a*, and b*) also increased with increasing carcass weight. However, moisture content and Warner–Bratzler shear force decreased with increasing carcass weight. A decrease in the compositions of type I and IIA fibers and an increase in the composition of type IIB fibers were observed with increasing carcass weight. The heavier carcasses showed type I and IIB fibers of bigger size and a smaller size of type IIA fibers. Fiber number percentage and the diameter of type IIB showed a significant positive correlation with carcass weight, fat content, and lightness (p?<?0.05). Fiber diameter of type IIB was positively correlated with loin-eye area, but was negatively correlated with moisture content. However, muscle fiber characteristics had no correlation with back-fat thickness, ultimate pH, Warner–Bratzler shear force, and b* value. In conclusion, crossbred pig which has of high composition and size of type IIB has high lightness (L* value) and water-holding capacity (drip loss). Therefore, excessively high weight of carcass has influence on pale and exudative properties in pig because of muscle fiber characteristics, especially type IIB fiber. 相似文献