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In spinning basalt fibres, the drafting force is in the same range as in spinning of glass fibres. The effect of the drafting
force can not be considered in the calculation for the strength and rigidity of the bottom of the spinneret.
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Translated from Khimicheskie Volokna, No. 5, pp. 47–50, September–October, 2007. 相似文献
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The transport properties of ionic liquids (ILs) are crucial properties in view of their applications in electrochem-ical devices. One of the most important advantages of ILs is that their chemical–physical properties and conse-quently their bulk performances can be well tuned by optimizing the chemical structures of their ions. This will require elucidating the structural features of the ions that fundamentally determine the characteristics of the nanostructures and the viscosities of ILs. Here we showed for the first time that the“rigidity”, the order, and the compactness of the three-dimensional ionic networks generated by the anions and the cation head groups determine the formation and the sizes of the nanostructures in the apolar domains of ILs. We also found that the properties of ionic networks are governed by the conformational flexibility and the symmetry of the anion and/or the cation head group. The thermal stability of the nanostructures of ILs was shown to be con-trolled by the sensitivity of the conformational equilibrium of the anion to the change of temperature. We showed that the viscosity of ILs is strongly related to the symmetry and the flexibility of the constitute ions rather than to the size of the nanostructures of ILs. Therefore, the characteristics of the nanostructures and the viscosities of ILs, especially the thermal stability of the nanostructures, can be fine-tuned by tailoring the symmetry and the conformational flexibility of the anion. 相似文献
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Investigation of the effects of fatty acids on the compressive strength of the concrete and the grindability of the cement 总被引:1,自引:0,他引:1
In cement industry, a great energy consumption has been observed during grinding of clinker. To reduce this consumption, some waste products have been used as grinding aids.In this investigation, the effects of sunflower oil (SO), oleic acid (OA), stearic acid (SA), myristic acid (MA) and lauric acid (LA) on the fineness and strength of the cement have been examined. These aids were added into clinker in certain ratios based on the cement clinker weight and the grinding has been done for a definite time at the same condition.All of the fatty acids used increased the fineness as compared with the cement without the grinding additives. SO and OA decreased the strength significantly, LA decreased it to a lesser extent and SA increased it definitely according to the common cement. But MA did not alter the strength of the cement as much as SA. In addition, the covering of the balls influences the grinding of cement clinker unfavourably. 相似文献
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V. A. Sirenek 《Glass Physics and Chemistry》2013,39(3):341-346
A hyperbolic equation (wave model) was used to take into account the relaxation character of mass transfer at the simulation of the diffusion stage of the formation of GRIN lenses. The results of the calculations are presented in accordance with wave and classic models. 相似文献
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Polyurethaneureas (PUU), which were synthesized from 4,4′-diphenylmethane diisocyanate (MDI), poly(ethylene glycol) (PEG), and 3,5-diaminobanzoic acid (DABA), were used as polyelectrolytes in this study. Differential scanning calorimetry (DSC) and Fourier transform infrared spectroscopy (FT-IR) were used to monitor the effect of the various kinds of PEG on the changes in morphology of PUU electrolytes corresponding to the concentration of lithium perchlorate (LiClO4) dopants. The results of DSC and FT-IR indicate the Li+ ions coordinate with the soft and hard segments. Additionally, the crystallinity of the PEG soft segment and the ordered hydrogen-bonded urea carbonyl groups decreased with increasing salt concentration. Impedance spectroscopy (IS) measurements show that the PUU electrolyte with the high phase separation degree has the high ionic conductivity. The hard-segment Tg and the soft-segment Tm influence the conductivity behavior of polyelectrolytes with increasing measurement temperature. 相似文献
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We consider the process of fracture of a solid celestial body with a certain strength entering a planetary atmosphere. Using
an integral approach in fracture mechanics, we show that the process of fragmentation of a meteorite occurs in several stages
and is completed when the maximum value of the aerodynamic drag is reached. The characteristic size of the fragments formed
depends on the properties of the meteorite material. At the end of fragmentation, the stage of rapid deceleration of the fragments
begins: “pumping” the energy of the meteorite into a shock wave. The proposed technique is illustrated using the examples
of the interaction of the Tunguska meteorite with the Earth's atmosphere and the interaction of Comet Shoemaker—Levy with
Jupiter's atmosphere.
All-Union Scientific Research Institute of Experimental Physics, Sarov 607200. Translated from Fizika Goreniya i Vzryva, Vol.
31, No. 6, pp. 117–124, November–December, 1995. 相似文献
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组合凹模的应力分析是一个非常复杂的问题,对其进行精确分析是解决模具寿命的关键。本文采用有限元分析软件Ansys对转子的组合凹模进行了分析,为转子组合凹模的优化设计提供了依据。 相似文献
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以气煤、肥煤、焦煤、瘦煤为样煤,进行了样煤的粉碎、有机溶剂溶胀和硝酸氧化处理,考察了处理后煤样中的药用腐植酸得率。结果表明,吡啶和N,N-二甲基吡咯烷酮是溶胀较好的溶剂;样煤粉碎后,随着粒度的减小,煤的溶胀率增加;粒度粉碎至200目的气、肥煤经吡啶溶胀和硝酸氧化后,煤样的药用腐植酸得率可达到73.0%和71.4%,而经甲醇溶胀和硝酸氧化的200目气煤药用腐植酸得率为56.4%和58.4%。实验结果表明,煤样经过溶胀和硝酸氧化处理,对药用腐植酸的提取有促进作用。 相似文献
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The effect of the hugh-temperature (800–1000°C) treatment in air of the Cr2O3/Al2O3 catalyst, which contained 18Cr2O3 + 0.4Na+, wt % and was prepared under laboratory conditions with the use of Pural SB1 grade high-purity pseudoboehmite, on the variation in the phase composition of the catalyst, specific surface, and catalytic characteristics in the dehydrogenation reaction of n-butane (yield and selectivity by ΣC4 olefins and 1,3-butadiene, conversion of n-butane) was investigated depending on the calcination temperature of the catalyst. It is shown that thermal stability depends on the following main factors: the method preparation of catalysts, the phase composition of the starting aluminum hydroxide, carrier texture, and the presence of modifying additions and impurities of other metals. In the case of the same chemical composition of the catalyst, the samples obtained by the wet mixing of pseudoboehmite with an aqueous solution of chromic anhydride are most thermally stable compared with the impregnation samples. It is established that the addition of cerium improves the thermal stability and activity of the impregnation Al-Cr catalyst, while the impurity of the Fe3+ ions (up to 0.1 wt %) does not worsen these characteristics. The investigated samples of the catalyst are more thermally stable than the imported industrial catalyst, which loses activity and specific surface after calcination at 900–1000°C. The determination of the thermal stability of fresh catalysts and the factors affecting it can be used as the preliminary evaluation of the future lifetime of catalysts. 相似文献