Forecasting of dissolved oxygen in the Guanting reservoir using an optimized NGBM (1,1) model

An optimized nonlinear grey Bernoulli model was proposed by using a particle swarm optimization algorithm to solve the parameter optimization problem. In addition, each item in the first-order accumulated generating sequence was set in turn as an initial condition to determine which alternative would yield the highest forecasting accuracy. To test the forecasting performance, the optimized models with different initial conditions were then used to simulate dissolved oxygen concentrations in the Guanting reservoir inlet and outlet (China). The empirical results show that the optimized model can remarkably improve forecasting accuracy, and the particle swarm optimization technique is a good tool to solve parameter optimization problems. What's more, the optimized model with an initial condition that performs well in in-sample simulation may not do as well as in out-of-sample forecasting.     

Forecasting of dissolved oxygen in the Guanting reservoir using an optimized NGBM (1,1) model

An optimized nonlinear grey Bernoulli model was proposed by using a particle swarm optimization algorithm to solve the parameter optimization problem. In addition, each item in the first-order accumulated generating sequence was set in turn as an initial condition to determine which alternative would yield the highest forecasting accuracy. To test the forecasting performance, the optimized models with different initial conditions were then used to simulate dissolved oxygen concentrations in the Guanting reservoir inlet and outlet (China). The empirical results show that the optimized model can remarkably improve forecasting accuracy, and the particle swarm optimization technique is a good tool to solve parameter optimization problems. What's more, the optimized model with an initial condition that performs well in in-sample simulation may not do as well as in out-of-sample forecasting.     

宜昌市水环境质量红线划分与空间管控研究

在宜昌市水环境质量红线划分中,对饮用水源保护区划分、水环境功能区划分和流域控制单元划分给予评估,分析在城市水环境质量红线划分上的可取之处,在自然社会综合系统框架下创造性的提出了适应宜昌城市环境总体规划中水环境质量红线划分的原则、技术方法和分级管控措施,提出的原则与适宜的管控措施为宜昌市水环境质量改善、环境公共服务实现与生态城市建设提供了支持,丰富并实践了生态保护红线体系.     

Effect of plant harvest on methane emission from two constructed wetlands designed for the treatment of wastewater

The emission of methane from two constructed wetlands [a free water surface flow system (FWS) and a subsurface flow system (SF)], constructed for the treatment of waste water, was evaluated at different sites inhabited by reeds (Phragmites communis), to test the effects of plant harvest. High methane emission was recorded immediately after harvesting in both wetlands. Several days after harvesting, the emission decreased in the FWS but remained high in the SF. The variation was significantly influenced by temperature, with lower emission and higher dissolved CH(4) in water occurring at lower temperatures. Both the emission and concentration of dissolved CH(4) were also influenced significantly by water quality, wetland design, level of stalk butt left above the water level, etc. The methane flux was explained on the basis of rizhospheric methanogenic and methanotrophic microbial populations. FISH analysis indicated the presence of Type A and Type B methanotrophs in both wetlands, and the methane flux was directly influenced by the quantitative variation in methanogenic and methanotrophic bacteria in both wetlands.     

某炼化企业催化汽油吸附脱硫装置职业病危害控制效果评价

通过资料调研、现场调查与检测，将获取的资料与法律、法规和标准要求相比较，对某炼化企业催化汽油吸附脱硫装置进行了职业病危害控制效果评价。     

Soil ecotoxicity assessment using cadmium sensitive plants

Four crop plant species (sweet corn, Zea may; wheat, Triticum aestivum; cucumber, Cucumis sativus; and sorghum, Sorghum bicolor) were tested to assess an ecotoxicity in cadmium-amended soils. The measurement endpoints used were seed germination and seedling growth (shoot and root). The presence of cadmium decreased the seedling growth. The medium effective concentration values (EC50) for shoot or root growth were calculated by the Trimmed Spearman-Karber method. Due to the greater accumulation of Cd to the roots, root growth was a more sensitive endpoint than shoot growth. Bioavailability and transport of Cd within plant were related to concentration and species. The ratio of bioaccumulation factor (BAF) in the shoots to the roots indicated high immobilization of Cd in the roots. Seed germination was insensitive to Cd toxicity, and is not recommended for a suitable assay. Among the test plants and test endpoints, root growth of sorghum and cucumber appears to be a good protocol to assess ecotoxicity of soils contaminated by Cd.     

自导式解说系统设计要素研究--以邓小平故居景区为例

以邓小平故居自导式解说系统的实际设计、制作为例,重点研究了自导式解说系统在设计中应当把握的四大要素,并对这四大设计要素在设计过程中的相互关系进行了理论研究和实例分析,指出这四大要素是旅游区设计出高水平、高质量的自导式解说系统的关键核心，从而使自导式解说系统成为提升旅游区整体形象的重要组成部分.     

因子分析法在江安河地表水水质评价中的应用

因子分析法是主成份分析方法的推广和深化，是把原来多个变量化为少数几个综合指标的一种统计方法。本文通过该法对江安河四川大学双流校区段水质进行了评价，结果表明，该水体受到了不同程度的有机物污染，其中非离子氨、阴离子洗涤剂、化学耗氧量，溶解氧所占的负荷最大。     

ADMINISTRATIVE,INSTITUTIONAL, AND STRUCTURAL CHARACTERISTICS OF AN ACTIVE WATER MARKET1

ABSTRACT: Voluntary water transfers through markets have been advocated by many diverse groups as a means to reallocate scarce water supplies in the semi-arid western U.S. Although transfers of water rights have occurred almost since the creation of prior appropriation laws over a century ago, functioning water markets have been very slow to develop and are few in number. The structure, composition, administration and transactions of one of the most well established water markets, shares in the Bureau of Reclamation, Colorado-Big Thompson project, are examined to better understand the institutional and transfer conditions that sustain an active water market. Results from a detailed study of C-BT project records reveal that between 1970 and 1993 there were 2,698 transactions through which over one-third of the project water changed ownership or type of use. Further analysis shows that the transactions involved many individual sellers and categories of buyers with different uses, including agricultural buyers. The transfer activity and efficiency of the C-BT market has lead some to suggest that it be used as a model for other markets. However, because this market has fewer institutional restrictions, a well developed infrastructure and unique market conditions, it will be difficult to transfer this model to other areas without accompanying modifications in water right administration and institutions.     

Comparison of field-observed and model-predicted plume trends at fuel-contaminated sites: implications for natural attenuation rates

Subsequent to modeling of natural attenuation processes to predict contaminant trends and plume dynamics, monitoring data were used to evaluate the effectiveness of natural attenuation at reducing contaminant concentrations in groundwater at seven fuel-contaminated sites. Predicted and observed contaminant trends at seven sites were compared in order to empirically assess the accuracy of some fundamental model input parameters and assumptions. Most of the models developed for the study sites tended to overestimate plume migration distance, source persistence, and/or the time required for the benzene, toluene, ethyl benzene, and xylenes (BTEX) plumes to attenuate. Discrepancies between observed and predicted contaminant trends and plume behavior suggested that the influence of natural attenuation process may not have been accurately simulated. The conservatism of model simulations may be attributed to underestimation of natural source weathering rates, overestimation of the mass of contaminant present in the source area, and/or use of overly conservative first-order solute decay rates.