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能源短缺、利用率低、环境恶化已经成为制约我国经济发展的重要环节。本文运用三阶段DEA模型对中国29个省市2009年的能源效率进行了分析。文章将技术效率分为纯技术效率和规模效率,并利用其数值来分析能源效率,同时,加入环境变量来分析完善上述计算结果。结果表明,在剔除外部因素和环境变量以前规模效率被高估,纯技术效率被低估。大部分省在第三阶段计算出的规模收益是递增的,这说明很多企业规模较小不能体现出规模经济性。从区域上来看则是东部地区的能源效率最高,中部次之,西部最低。针对这一结果,本文给出几点建议:中西部地区应加强合作,发挥各自优势,开发新技术新能源,提高能源利用率,促进经济健康发展。 相似文献
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Variations of Earth’s rotation rate (length-of-day, LOD) occur over a wide range of time scales from a few hours to the geological age. Studies showed that the 50-day fluctuation exists in LOD change. In the present paper, the authors use wavelet technique to study the 50-day oscillation in LOD series. Temporal variations of the oscillation are presented in this work. After analyzing the axial component of atmospheric angular momentum (AAM) and oceanic angular momentum (OAM), the 50-day periodic signal is also found in atmospheric and oceanic motion with remarkable time-variation. Meanwhile, the 50-day oscillation of the axial AAM is in good consistence with that of LOD change. This suggests that the 50-day oscillation of LOD change is mainly excited by the axial AAM. Possible origin of the oscillation for Earth system is discussed in the end of this paper. 相似文献
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Performance Evaluation of Constructed Wetlands Treating Wastewater Treatment Plant Effluent in Taihu Lake,China 下载免费PDF全文
Constructed wetlands are often used for advanced treatment of the secondary effluent of municipal wastewater treatment plants (WWTPs). Through assessing wetlands based on economic, technical, environmental, and social impacts, an optimal process is selected. In this study, a set of assessment methods for wetland treatment technology is established: The analytic hierarchy process (AHP) is used to establish the evaluation index system; the entropy weight method is employed to calculate the index weights; and the preference ranking organization method for enrichment evaluation (PROMETHEE) is utilized for ranking of the selected treatment technologies. Then four processes applied in Taihu Lake basin, China are evaluated. The results show the following ranking: Vertical‐flow wetland–ecological pond–surface‐flow wetland–horizontal‐flow wetland, vertical‐flow wetland–horizontal‐flow wetland, ecological pond–horizontal‐flow wetland–surface‐flow wetland, and ecological ditch–ecological pond. The wetland exhibits certain universality and space portability with regard to treatment of municipal WWTP effluent. From the view of comprehensive benefits, the ranking of the treatment technology based on the vertical‐flow wetland is high (Φ values between 0.0224 and 0.0349), whereas that based on the ecological pond is low (Φ values between ?0.2086 and ?0.2652), owing to the mechanism of the process itself and the role of microorganisms in the system. Moreover, for organic matter removal, a vertical‐flow wetland process is recommended (48%), whereas for the removal of N contamination, an integrated‐flow wetland process is suggested (31.2% for NH3‐N, 32.4% for TN removals). 相似文献
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文献报道的测定岩石矿物中锂、铷、铯的方法都是在硫酸或硝酸介质中做的,该介质只能测定这三种元素,这不能满足在同一试液中测定多种元素的需要。本文选用盐酸作为测定介质,不但可以取分液测定锂、铷、铯,还可以直接或另取分液加入干扰抑制剂测定其它元素。该法灵敏准确,精密度好,选择性高。一般熔物都是盐酸浸取,正好与本实验介质一致,因此不需另制专用试液。简化了分析手续,扩大了元素的分析范围。 相似文献
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对于含硫化物样品,用2:1逆王水分解,泡沫塑料吸附,缩短(或省去)了除硫和有机碳的灼烧时间,解决了矿石中含硫和有机碳高时,经长时间灼烧,硫、碳仍除不尽,致使金的分析结果偏低的问题。逆王水分解后的试样用泡沫塑料分离富集金,回收率在95%以上。高含量金火焰法测定,低含量金石墨炉法测定,操作极为方便快速。火焰法测定时,特征浓度为0.48ppm/l%吸收,VC为2—11%;石墨炉法测定时,绝对灵敏度为2.48×10-11g/l%吸收,VC为7.42%。 相似文献
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