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排序方式: 共有247条查询结果,搜索用时 15 毫秒
61.
Yucel BIROL 《中国有色金属学会会刊》2013,23(7):1875-1881
Precipitation during the industrial cool down takes place predominantly above 300 °C in the EN AW-6082 and 6005 alloys. The phase precipitation throughout cooling is equilibrium β phase. A considerable capacity is retained after the cool down for further precipitation during a subsequent heating cycle. The β-Mg2Si is once again the predominant phase that forms during a scan heating cycle employed in exactly the same manner with the industrial billet preheating operation. The precipitation in the 6060 alloy, on the other hand, occurs predominantly below 300 °C with additionally β′-Mg2Si particles formed below 200 °C. 相似文献
62.
In present work; epoxidized soybean oil (ESO), fly ash (FA) and natural clay (C) are used to produce 45 kinds of biocomposite
materials and by analyzing the physical–mechanical properties of these novel materials, their use as an insulation material
is investigated. The compressive strength, tensile strength, abrasion loss, thermal conductivity and oven-dry mass of each sample are measured.
The minimum thermal conductivity of 0.273 W/mK is observed with the samples containing ESO–FA–C. It is increased with the
decrease of ESO and FA. The compressive and tensile strengths are varied from 13.53 to 6.31 MPa and 1.287 to 0.879 MPa, respectively. 相似文献
63.
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65.
Railway and train security are very important in preventing service disruption and ensuring quality and safe journeys. Conventional gauges are used in laboratory environments for the strain measurement of rails used in railways. However, the use of these electrical sensors is not practical in long-distance railways. Instead, access to long distances is possible with fiber optic sensors. In this study, the strain of 49E1 type rail with R260 hardness and quality was calculated theoretically. These results were compared with an experimentally established fiber Bragg grating system. Moreover, a user-friendly interface was prepared for real-time monitoring of the system. Upon examining the results, the maximum deviation at a rate of 2.5% occurred in the strain measurement in the rail in response to force changes between 0 and 200 kN. A value of approximately 1.38?pm/µε was calculated between the wavelength/strain changes. 相似文献
66.
In Rhizopus oryzae cultivations, lactate production decreased and ethanol and biomass productions increased as inoculated spore concentration increased. Spore concentrations of 1 x 10(3) and 1 x 10(4) spores ml(-1) induced tightly packed clumps, whereas 1 x 10(5) and 1 x 10(6) spores ml(-1) induced filamentous growth. 相似文献
67.
Hansu Birol Dragan Damjanovic Nava Setter 《Journal of the American Ceramic Society》2005,88(7):1754-1759
The processing and characterization of electrical properties of potassium niobate ceramic, KNbO3 (KN) have been studied. The difficulty of obtaining dense samples by conventional methods limits the knowledge on electrical properties of this material. In this paper, a complete route for processing of KN with density over 94% is described. Piezoelectric and dielectric data are presented. It is observed that the major problem concerning the density is related to incorrect stoichiometry, which is believed to be a more critical issue for this system compared with other electro-ceramics. 相似文献
68.
In supply chain management process, the firm select best supplier takes the competitive advantage to other companies. Thus, supplier selection is an important issue and with the multiple criteria decision-making approach, the supplier selection problem includes both tangible and intangible factors. This paper is aimed to present an integrated fuzzy and linear programming approach to the problem. Firstly, linguistic values expressed in trapezoidal fuzzy numbers are applied to assess weights and ratings of supplier selection criteria. Then a hierarchy multiple model based on fuzzy set theory is expressed and fuzzy positive and negative ideal solutions are used to find each supplier’s closeness coefficient. Finally, a linear programming model based on the coefficients of suppliers, buyer’s budgeting, suppliers’ quality and capacity constraints is developed and order quantities assigned to each supplier according to the linear programming model. The integrated model is illustrated by an example in a textile firm. 相似文献
69.
70.
Yücel Birol 《Journal of Materials Science》1999,34(7):1653-1657
Aluminum has been a key material, particularly in the aerospace and automotive industries, owing to its low density, high specific strength, good corrosion resistance and recyclability. Aluminum based metal matrix composites have also become attractive candidates for various applications where monolithic aluminum alloys cannot meet the strict design requirements. Recently, particulate reinforced aluminum composites have attracted a great deal of attention. Among various techniques which have been employed in the synthesis of these composites, incorporation of the reinforcing phase particles directly into the melt is practical and economic; yet it is not trouble-free. In situ processing of particulate reinforced composites, on the other hand, yields superior microstructures and thus better properties. In the present work, such a method to manufacture TiCp-Al composites and the microstructures obtained thereof will be described. 相似文献