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D. Brikić 《Petroleum Science and Technology》2013,31(4):366-377
Abstract The purpose of this is the determination of appropriate friction factor and selection of a representative equation for natural gas flow under the presented conditions in the network. Calculation of the presented looped gas pipeline network is done according to principles of Hardy Cross method. The final flows were calculated for known pipe diameters and nodes consumptions while the flow velocities through pipes have to stand below certain values. In optimization problems flows are treated as constant, and the diameters are variables. 相似文献
994.
This article presents a novel tree‐shaped antenna with wideband and end‐fire properties designed by the Competitive Algorithm of Simulating Natural Tree Growth. The antenna has an impedance bandwidth of 27.2% for S11 < ?10dB, maintains end‐fire radiation pattern and achieves a high gain over the entire frequency band from 5.4 GHz to 7.1 GHz. © 2010 Wiley Periodicals, Inc. Int J RF and Microwave CAE, 2010. 相似文献
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David Antonio Pereira de Abreu Perfecto Paseiro Losada Julio Maroto José M. Cruz 《Packaging Technology and Science》2011,24(6):353-360
The capacity of the natural antioxidant to retard oxidation of polyunsaturated fatty acids in hake (Merluccius merluccius) muscle was investigated. Hake fillets were packaged in low‐density polyethylene with the natural antioxidant (sample C1 = 7 mg/dm2 film and sample C2 = 24 mg/dm2 film) or without the antioxidant (control sample) and frozen for 12 months at ?20°C. The results confirm the efficacy of an active packaging with a natural antioxidant derived from barley husks to slow the progress of lipid hydrolysis and increase oxidative stability in hake muscle. Determination of peroxide value, conjugated dienes, free fatty acids, thiobarbituric acid reactive substances (TBARS) and anisidine value (AV) proved suitable for studying lipid hydrolysis and primary and secondary lipid oxidation over time. After 6 months of frozen storage, the TBARS levels were lower in hake packed with low‐density polyethylene with the natural antioxidant (C1 and C2) than in the control sample; at month 12, the TBARS values of C1 and C2 were lower (16 and 21%, respectively) than the control samples. AVs observed in samples C1 and C2 at month 9 were lower than those observed in the control sample at month 12. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献
997.
Holden Mark P.; Curby Kim M.; Newcombe Nora S.; Shipley Thomas F. 《Canadian Metallurgical Quarterly》2010,36(3):590
Memories for spatial locations often show systematic errors toward the central value of the surrounding region. This bias has been explained using a Bayesian model in which fine-grained and categorical information are combined (Huttenlocher, Hedges, & Duncan, 1991). However, experiments testing this model have largely used locations contained in simple geometric shapes. Use of this paradigm raises 2 issues. First, do results generalize to the complex natural world? Second, what types of information might be used to segment complex spaces into constituent categories? Experiment 1 addressed the 1st question by showing a bias toward prototypical values in memory for spatial locations in complex natural scenes. Experiment 2 addressed the 2nd question by manipulating the availability of basic visual cues (using color negatives) or of semantic information about the scene (using inverted images). Error patterns suggest that both perceptual and conceptual information are involved in segmentation. The possible neurological foundations of location memory of this kind are discussed. (PsycINFO Database Record (c) 2010 APA, all rights reserved) 相似文献
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邱宝庆 《昆明冶金高等专科学校学报》2010,26(5):75-79
现代矿产资源的开发,既要面对开采难度大,矿石品位低的问题,还要面对非常严格的环境保护要求和较高的环境保护成本等问题。以某超大型低品位铜矿为例,通过对矿山总体布局的探索,以及新技术、新工艺、新设备的应用,在环境保护与提高经济效益两个方面取得了突破,不仅有效地解决了矿山开发的环境保护问题,也在一定程度上解决了低品位矿石开采的经济效益问题。 相似文献
1000.
水利水电工程一般多因地制宜,就地取材,有适合的当地天然建筑材料,以致成为决定建筑物类型和工程造价的决定性因素。文章分析了区域地形、地貌、地层、岩性等,通过地质调查、钻探、坑探等勘察手段,寻找到了设计需要的建坝的各种材料。同时,使用野外和室内土工实验方法,研究了这些建材的物理、力学性质。在此基础上根据平均厚度法和设计、规范标准对各料场建材进行了计算和评价,其质量和数量均满足要求,为该工程设计和施工提供了可靠的建材依据。 相似文献