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131.
Liming Yuan Alex C. Smith 《Journal of Loss Prevention in the Process Industries》2013,26(6):1321-1327
Laboratory experiments were conducted to investigate carbon monoxide (CO) and carbon dioxide (CO2) emissions from spontaneous heating of three U.S. coal samples in an isothermal oven at temperatures between 50 and 110 °C. The oxygen (O2) concentration of an oxygen/nitrogen (N2) mixture flowing through the coal sample was 3, 5, 10, 15, and 21%, respectively. The temperature at the center of the coal sample was continuously monitored, while the CO, CO2, and O2 concentrations of the exit gas were continuously measured. The results indicate that the CO and CO2 concentrations and the CO/CO2 ratio increased when the initial temperature was increased. As the inlet O2 concentration increased, the CO and CO2 concentrations increased, while the CO/CO2 ratios tended to converge to the same value. The ratio of CO/CO2 was found to be independent of coal properties, approaching a constant value of 0.2. The maximum CO production rate correlated well with the maximum coal temperature rise. The apparent order of reaction for coal oxidation was estimated to be between 0.52 and 0.72. The experimental results in this study could be used for early detection and evaluation of a spontaneous heating in underground coal mines. 相似文献
132.
Helsel DR 《Chemosphere》2006,65(11):2434-2439
The most commonly used method in environmental chemistry to deal with values below detection limits is to substitute a fraction of the detection limit for each nondetect. Two decades of research has shown that this fabrication of values produces poor estimates of statistics, and commonly obscures patterns and trends in the data. Papers using substitution may conclude that significant differences, correlations, and regression relationships do not exist, when in fact they do. The reverse may also be true. Fortunately, good alternative methods for dealing with nondetects already exist, and are summarized here with references to original sources. Substituting values for nondetects should be used rarely, and should generally be considered unacceptable in scientific research. There are better ways. 相似文献
133.
通过回归分析法研究造纸与印刷业上市公司的环保投资与财务绩效的相关性,发现两者之间呈显著的正向线性关系。将环保投资按不同结构分类,发现污染预防投资比末端治理投资带来的财务绩效更明显,环保固定资产投资比技术投资在短期内带来的财务效益更明显。 相似文献
134.
Floods are among the world's most devastating natural disasters, causing immense damage and accounting for a large number of deaths world-wide. Good flood management policies play an extremely important role in preventing floods. It is well known that China has more than 5000 years of experience in flood management policy beginning with the reign of DaYu and Gun. Although culturally related, Japanese flood management developed differently from that of China. Under rapid development of civil engineering technology, flood management was achieved primarily through the construction of dams, levees and other structures. These structures were never adequate to stop all floods, and recent climate change driven extreme events are ever more frequently overwhelming such infrastructure. It is important to take a historical perspective of Japanese and Chinese flood management in order to better manage increasingly frequent extreme events and climate change. We present insights taken from an historical overview of Japanese and Chinese flood management policies in order to guide future flood risk management policy. 相似文献
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137.
Forestry Best Management Practices (BMPs) were developed to protect water quality. In the eastern US, those BMPs were often expanded to include maintenance of site productivity. Generally, BMPs recommend the use of pre-harvest planning and careful design for construction of roads and other activities that expose bare soil, minimizing trafficking and areas of bare soil, maintaining streamside management zones, ensuring rapid revegetation following harvesting, minimizing soil disturbance, and ameliorating severe trafficking with site preparation. This review of peer-reviewed research from the past 20 years examined the effects of forest harvesting and site preparation on water quality and site productivity in the eastern US. The review was subdivided into areas having relatively similar physiography and land management (New England, Lake States, Appalachian Plateau, Ridge and Valley, Blue Ridge, Piedmont, Atlantic Coastal Plain, Gulf Coastal Plain, and Ouachitas-Ozarks). In general, data from steeper physiographic regions indicated that forest harvesting and site preparation can increase erosion, sediment and nutrient losses to streams. However, the quantities introduced into streams tended to be relatively low, generally below the values that are considered acceptable for alternative land uses. Also most research indicated that water quality recovers within two to five years following forest operation disturbances, particularly if BMPs are employed. Research from the less mountainous and often more poorly drained Lake States and Coastal Plain regions indicated that soil compaction and rutting may or may not cause site productivity effects, depending on soil types, natural ameliorative properties and site preparation. Overall, the research supports the forestry BMPs recommended in the eastern states. 相似文献
138.
环境中常见的寄生虫(卵)有蛔虫、肝吸虫、血吸虫、贾第鞭毛虫和隐孢子虫等,针对其特点已形成以虫卵密度、免疫和血清特性等为基础的检测方法,比较分析不同寄生虫不同检测方法的准确度、精确度、回收率差异及优缺性,为实际工作提供技术依据。 相似文献
139.
日本作为对二噁英的研究和控制取得较大成就的国家之一,在二噁英实验室检测方面一直走在世界的前列,本文简单介绍日本近年来二噁英检测以及分解技术的发展。 相似文献
140.
SUMMARY This paper reviews the nature of technological changes in forestry and the forest industries and their impacts on forest conservation and deforestation. While noting that technological changes have made available substantially more forest products to consumers, with higher quality and/or at lower prices than would otherwise have been possible, not all impacts have been positive. The authors take a long-term perspective of how changes in technologies, markets and transportation are likely to affect the management and conservation of tropical forests. The paper defines a research challenge to direct and harness science and innovation towards increasing the productivity of forests and reducing the environmental costs associated with forest industries and products. 相似文献