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31.
32.
《Energy Policy》2005,33(2):133-150
In order to forecast the technological development and cost of wind turbines and the production costs of wind electricity, frequent use is made of the so-called experience curve concept. Experience curves of wind turbines are generally based on data describing the development of national markets, which cause a number of problems when applied for global assessments. To analyze global wind energy price development more adequately, we compose a global experience curve. First, underlying factors for past and potential future price reductions of wind turbines are analyzed. Also possible implications and pitfalls when applying the experience curve methodology are assessed. Second, we present and discuss a new approach of establishing a global experience curve and thus a global progress ratio for the investment cost of wind farms. Results show that global progress ratios for wind farms may lie between 77% and 85% (with an average of 81%), which is significantly more optimistic than progress ratios applied in most current scenario studies and integrated assessment models. While the findings are based on a limited amount of data, they may indicate faster price reduction opportunities than so far assumed. With this global experience curve we aim to improve the reliability of describing the speed with which global costs of wind power may decline. 相似文献
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《International Journal of Pressure Vessels and Piping》2005,82(5):407-416
Plastic collapse of pipe bends with attached straight pipes under combined internal pressure and in-plane closing moment is investigated by elastic–plastic finite element analysis. Three load histories are investigated, proportional loading, sequential pressure–moment loading and sequential moment–pressure loading. Three categories of ductile failure load are defined: limit load, plastic load (with associated criteria of collapse) and instability loads. The results show that theoretical limit analysis is not conservative for all the load combinations considered. The calculated plastic load is dependent on the plastic collapse criteria used. The plastic instability load gives an objective measure of failure and accounts for the effects of large deformations. The proportional and pressure–moment load cases exhibit significant geometric strengthening, whereas the moment–pressure load case exhibits significant geometric weakening. 相似文献
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36.
《Composites Science and Technology》2007,67(7-8):1330-1339
In order to analyze the effect of an epoxidized natural rubber (ENR) and filler treatment on the morphology and behavior of natural rubber (NR) nanocomposites, blends of these polymers have been prepared. The nature and extent of the clay dispersions in the filled samples were evaluated by X-ray diffraction. In the presence of ENR, an exfoliated structure was obtained which suggests that enough rubbery polymer was incorporated into the interlayer spacing. The effect of clay in rubber compounds was analyzed through rheological, mechanical and swelling characterization. A sensible improvement in the nanocomposite properties was observed by the addition of organoclay. It has been deduced that the properties of the compounds strongly depend on the extent of the silicate nanolayers dispersion into the rubber matrices as well as on the organoclay type and elastomer compatibility. 相似文献
37.
Y. Lu 《Journal of Materials Science》2003,38(5):1081-1085
A Golden Section approach combined with relational grade analysis is proposed as an experimental design tool helpful in the development of new automotive friction materials. Golden Section was used to design the volume fraction of the components systematically. The changes in friction performance (friction coefficient and wear) measured using Friction Assessment and Screening Test (FAST) can be correlated with component variations by use of relational grade analysis. This approach was utilized to optimize a non-metallic friction material containing seven ingredients including two fibers (aramid and slag fiber), four fillers (Al2O3, BaSO4, graphite and nitrile rubber) and one binder (benzoxazine). The volume fraction of seven components was varied simultaneously in order to optimize the parameters of friction coefficient and wear with a minimum number of tests. Three phases were performed to find the optimal proportion of the components. The optimized friction performance was obtained after doing 19 formulation experiments. 相似文献
38.
Aroused problems in the deposition of diamond-like carbon films by using the liquid phase electrodeposition technique 总被引:2,自引:0,他引:2
He-Sun Zhu Jin-Ting Jiu Qiang Fu Hao Wang Chuan-Bao Cao 《Journal of Materials Science》2003,38(1):141-145
Hydrogenated diamond-like carbon (DLC) films were prepared by using liquid phase electrodeposition technique. The effects of the applied potential and the carbon sources on the deposition process and film structures were studied. It has been found that the organic liquids with high dielectric constants, small viscosities and the methyl group bonding to the polar group are appropriate carbon sources. The increasing of potential improves the formation of sp3 carbon during the deposition process. In a high electric field, organic molecules are polarized and reacted on the surface of the electrode, turning out DLC and other products. It is believed that the reaction follows a polarization-reaction mechanism. 相似文献
39.
《Materials Letters》2007,61(19-20):4027-4030
Ultra-fine polyimide fibers containing silver nanoparticles were prepared by electrospinning from poly(amic acid)/(trifluoroacetylacetonoto)silver(I) (PAA/AgTFA) solution. Thermal curing of the silver(I)-containing fibers led to cycloimidization of the poly(amic acid) into polyimide with concomitant silver(I) reduction. The polyimide–silver fibers were characterized by FT-IR, X-ray diffraction, scanning electron microscopy, and transmission electron microscopy. The average diameters of silver nanoparticles and ultra-fine PI fibers electrospun from solutions with different amounts of AgTFA were studied, and the crystal structure of silver nanoparticles was also presented. 相似文献
40.