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The hydrogen fuel cell is a promising option as a future energy resource; however, the nature of the gas is such that the conversion process of other fuels to hydrogen on board is necessary. Among the raw fuel resources, methane could be the best candidate as it is plentiful. In this experiment, the possibility of producing hydrogen with less carbon formation from methane by a dielectric barrier discharge (DBD) was investigated. Without the addition of a catalyst, the formation of hydrogen reached between 30% and 35% at methane residence time of 0.22 min and supplied powers in the range of 60-130 W. The hydrogen selectivity increased at higher supplied power, but the process efficiency, defined as a ratio of the produced hydrogen to the supplied power, decreased slightly. In order to boost the hydrogen production with less carbon formation, a mixed oxide catalyst of zinc and chromium was added to the reactor. It was shown that the production of hydrogen was ca. 40% higher than the non-catalytic plasma process. 相似文献
74.
健康黄河的内涵及其指标 总被引:18,自引:4,他引:14
本文从河流的自然和社会属性角度,基于健康河流的概念阐述了河流生命、河流健康的科学内涵,认为河流健康是人们对河流生命存在状态的描述,健康的河流是河流的社会功能与自然功能能够取得平衡的河流。河流的健康应包括连续的河川径流、通畅安全的水沙通道、良好的水质、良性运行的河流生态系统和一定的供水能力。利用黄河1956~2004年实测资料,论证了表征健康黄河标志的低限流量、河道最大排洪能力、平滩流量、滩地横比降、水质类别、湿地规模、水生生物、供水能力等指示因子的阈值范围。 相似文献
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Nutrient availability has long been considered one of the most important factors regulating production of benthic algae in oligotrophic rivers; yet, empirical relationships do not have as wide an application as similar models derived for lentic systems. The aim of this research was to derive empirical relationships between nutrient concentrations and benthic algal abundance and to identify commonalities with other studies to improve our understanding of constraints on algae in oligotrophic rivers. Surveys of physical, chemical and biological attributes of oligotrophic mountain rivers in spring, summer and autumn for 2 years confirmed that small amounts of anthropogenic phosphorus (0.1–5.6 µg/L total phosphorus (TP)) resulted in 4‐ to 30‐fold increases in abundance of benthic algae and benthic macroinvertebrates (BMIs). Algal accrual along a gradient in nutrient availability was not masked by grazing pressure but was positively correlated with abundance of scrapers. Epilithic abundance was highest downstream of anthropogenic nutrient sources in autumn. We concluded that benthic algal abundance in these mountain rivers was weakly correlated with phosphorus availability if light was not limiting but ultimately controlled by temperature and river discharge. Therefore, we recommend more direct measures of nutrient limitation be used to predict changes in ecological integrity at the lower end of the resource gradient. Copyright © 2007 John Wiley & Sons, Ltd. 相似文献
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Tungsten carbide nanopowders were synthesized successfully by electric discharge machining followed by annealing under a nitrogen atmosphere. The tungsten workpieces were initially melted and evaporated on the working surface during the electric discharge machining process, and then the tungsten powders were reacted with the carbon electrode and the working medium of kerosene to form the nanocrystalline WC1−x powders. The powders produced were characterized by XRD, SEM, and TEM. When annealing the powders under an N2 atmosphere, the cubic phases of WC1−x gradually changed to hexagonal W2C and then were transformed fully to nanocrystalline hexagonal WC at 1200 °C, with the nanocrystalline tungsten carbide encapsulated in a carbon shell. On the other hand, under an H2 atmosphere, the WC1−x phase changed via a W2C phase to reduced powders of pure tungsten at 1000 °C or were reduced directly from WC1−x to elemental W. 相似文献
79.
Yoo‐Seong Kim Woong‐Sik Kim Hak‐Nyun Choi Tae‐Geum Koh Yong‐Seog Kim 《Journal of the Society for Information Display》2007,15(3):199-204
Abstract— Among various barrier‐rib manufacturing processes, the mold‐pattern‐transfer method has potential to reduce processing cost as well as the manufacture of high‐resolution pixels. In this study, the effects of major processing variables of the mold‐pattern‐transfer process on the formation of air‐trapped pores within barrier ribs were examined. The results indicated that with an optimum combination of the processing variables, barrier ribs without trapped defects can be produced, demonstrating the possibility of reducing the number of processing steps and costs of barrier ribs. 相似文献
80.
对焦化厂生产废水的来源及污染指标进行了分析,介绍了金马焦化公司废水的净化处理、回收循环利用,以及实现焦化厂生产废水零排放,提高资源利用率的探索与实践. 相似文献