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121.
Shing-Fu Hsueh Robert C. Ahlert 《Journal of the American Water Resources Association》1978,14(6):1404-1416
ABSTRACT: An input-output method, using a network of ideal continuous stirred-tank and plug-flow tublar reactors, is adopted to analyze residence time distribution data for a separated mechanical aeration system. The usefulness of this modeling concept is enhanced by its simplicity, especially in the presence of a first-order reaction. This facilitates use of the model format for wastewater quality prediction. Moreover, first-order rate constants can also be estimated from the model, if conversions due to the reaction rate are available. 相似文献
122.
K. V. Slack J. W. Nauman L.J. Tilley 《Journal of the American Water Resources Association》1979,15(1):108-135
ABSTRACT: Benthic invertebrate faunas were compared to two fifth-order streams, the Atigun River flowing northward and the Dietrich River flowing southward. Sixty-eight taxa were collected, forty-nine from each stream. Aquatic insects comprised 88% of the taxa and 97% of the individuals from the Dietrich River and 73% of the taxa and 97% of the individuals from the Atigun River. Diptera, especially Chironomidae, were most abundant. Plecoptera, Ephemeroptera, Oligochaeta, Acarina, and Collembola were significant. In both streams the headwaters were dominated by the subfamily Diamesinae which was replaced by Orthocladiinae downstream. Diversity seemed to increase with stream order. Cluster analysis showed a high degree of resemblance between the benthic faunas of the rivers. Faunal resemblance decreased with increasing distance between stations, both within and between the streams. Although some taxa may occur in only one stream, the evidence for faunal resemblance is stronger than for faunal differences. Other studies have shown that differences in total radiation associated with valley aspect affect local climate, hydrology, and distribution of terrestrial plants and animals. However, the benthic faunas of Atigun and Dietrich Rivers were remarkably similar. Factors which operate independently of aspect, possibly freezing solid in winter, may control the occurrence of species in these streams. 相似文献
123.
Stephen J. Burges 《Journal of the American Water Resources Association》1979,15(1):227-243
ABSTRACT: Components contributing to uncertainty in the location of the flood plain fringe of a mapped flood plain are identified and examined to determine their relative importance. First-order uncertainty analysis is used to provide a procedure for quantifying the magnitude of uncertainty in the location of the flood plain fringe. Application of the procedure indicated that one standard deviation of uncertainty in flood plain inundation width was about one third of the mean computed inundation width for several flood population-flood geometry combinations. Suggested mapping criteria, which directly incorporate uncertainty estimates, are given. While these criteria are more suitable for use in developing areas than in flood plains that have had extensive development, the analysis procedure can be used to accommodate property owners who challenge the validity of estimated flood fringe boundaries. Use of uncertainty analysis in flood plain mapping should enhance the credibility of the final plan. 相似文献
124.
Il-Chung Kim 《Journal of Material Cycles and Waste Management》2002,4(1):12-22
This paper considers the current status of waste generation and waste treatment trends, and introduces a wide variety of policy
instruments for waste minimization at every stage of economic activity in Korea, i.e., production, distribution, and consumption.
At each stage, the Korean government has imposed a policy mix of direct regulations and economic incentives. These policy
instruments have made definite contributions to a reduction of waste generation and an increase in the recycling rate. Despite
these fruitful outcomes, there are still some shortcomings with respect to efficiency and equity. Among other aspects, this
paper examines three representative economic incentives – the charge system, the volume-based-collection fee system, and the
deposit–refund system – and identifies shortcomings in each. Some suggestions are made for the creation of better systems
of economic incentives. However, many experts insist that this kind of piecemeal change in each policy instrument is not enough
to achieve the ultimate goal of resource circulation and an environmentally friendly society, especially in Korea, which is
a country with little land, a high population density, and a high economic growth rate. Among experts, special emphasis is
placed on the activation of recycling industries to achieve these goals.
Received: April 2, 2001 / Accepted: September 10, 2001 相似文献
125.
江苏省旅游资源竞争力区际比较研究 总被引:3,自引:0,他引:3
从综合类、人文类、自然类3个旅游资源大类中分别选取世界遗产地、国家重点风景名胜区、中国优秀旅游城市、4A级旅游区、国家历史文化名城等11种旅游资源,采用绝对数量、人均密度、地均密度3种评价指标和位序得分法,对江苏省13个地级市的主要旅游资源进行了定量分析比较,得出13个地市旅游资源竞争力的强弱,并提出相关的旅游开发建议。 相似文献
126.
Dressel M 《Die Naturwissenschaften》2007,94(7):527-541
Low-dimensional organic conductors could establish themselves as model systems for the investigation of the physics in reduced
dimensions. In the metallic state of a one-dimensional solid, Fermi liquid theory breaks down and spin and charge degrees
of freedom become separated. But the metallic phase is not stable in one dimension: as the temperature is reduced, the electronic
charge and spin tend to arrange themselves in an ordered fashion due to strong correlations. The competition of the different
interactions is responsible for which broken-symmetry ground state is eventually realized in a specific compound and which
drives the system toward an insulating state. Here, we review the various ordering phenomena and how they can be identified
by optic and magnetic measurements. While the final results might look very similar in the case of a charge density wave and
a charge-ordered metal, for instance, the physical cause is completely different. When density waves form, a gap opens in
the density of states at the Fermi energy due to nesting of the one-dimension Fermi surface sheets. When a one-dimensional
metal becomes a charge-ordered Mott insulator, on the other hand, the short-range Coulomb repulsion localizes the charge on
the lattice sites and even causes certain charge patterns. We try to point out the similarities and conceptional differences
of these phenomena and give an example for each of them. Particular emphasis will be put on collective phenomena that are
inherently present as soon as ordering breaks the symmetry of the system. 相似文献
127.
水体沉积物是水生生态系统重要的组成部分,沉积物污染将影响整个水生生态系统,因此有必要构建科学全面的水体沉积物质量评价方法,为环境污染修复与监管提供科学依据。已有文献报道了多种沉积物质量评价方法。其中,证据权重法通过对不同的证据进行测定与整合,弥补了传统评价方法的不足,可以对沉积物质量进行科学全面的评价。本文对证据权重法中化学分析、生物毒性和底栖生物群落结构3种证据的测量方法、赋权方法、证据整合与信息解译方法进行了系统评述,并以淡水河为例介绍了用多目标决策理想点法(TOPSIS)整合数据进行沉积物质量综合评价的方法。 相似文献
128.
研究了在30℃左右条件下,流化床微生物燃料电池(FBMFC)处理有机废水的基质降解动力学。在空气阴极、单室、无膜液固流化床微生物燃料电池中,以污水和椰壳活性炭为液相和固相,通过实验考察不同水力停留时间的污水COD变化。选取Monod模型和简单动力学模型,通过合理的假设推导出流化床微生物燃料电池处理模拟有机废水时的基质降解动力学模型。将实验数据代入到理论推导得到的动力学模型中,进行线性拟合和对比分析,得到Monod模型和一级反应动力学模型表达式。结果表明流化床微生物燃料电池基质降解为一级反应;Monod模型表达式为:t/s0-st=4.769 7/st+15.885,一级动力学模型为:lnCA=-0.025 32t+8.109 15,理论推导模型与实验数据具有较好的吻合性。 相似文献
129.
130.
产品环境试验顺序的优化选择 总被引:2,自引:2,他引:0
首先介绍了产品进行环境试验的目的及其重要性,对环境试验项目之间的相互影响及合理顺序进行了分析,并阐述了选择环境试验项目顺序所遵循的一般原则,说明在进行环境试验时,必须针对具体试验项目,注意合理的试验顺序,才能确保试验结果的真实性、代表性和可比性。 相似文献