Modeling of a sequencing batch reactor treating municipal wastewater using multi-layer perceptron and radial basis function artificial neural networks

A sequencing batch reactor was modeled using multi-layer perceptron and radial basis function artificial neural networks (MLPANN and RBFANN). Then, the effects of influent concentration (IC), filling time (FT), reaction time (RT), aeration intensity (AI), SRT and MLVSS concentration were examined on the effluent concentrations of TSS, TP, COD and NH₄⁺-N. The results showed that the optimal removal efficiencies would be obtained at FT of 1 h, RT of 6 h, aeration intensity of 0.88 m³/min and SRT of 30 days. In addition, COD and TSS removal efficiencies decreased and TP and NH₄⁺-N removal efficiencies did not change significantly with increases of influent concentration. The TSS, TP, COD and NH₄⁺-N removal efficiencies were 86%, 79%, 94% and 93%, respectively. The training procedures of all contaminants were highly collaborated for both RBFANN and MLPANN models. The results of training and testing data sets showed an almost perfect match between the experimental and the simulated effluent of TSS, TP, COD and NH₄⁺-N. The results indicated that with low experimental values of input data to train ANNs the MLPANN models compared to RBFANN models are more precise due to their higher coefficient of determination (R²) and lower root mean squared errors (RMSE) values.     

The Use of Remote Sensing and GIS in the Sustainable Management of Tropical Coastal Ecosystems

The sustainable use and management of important tropical coastal ecosystems (mangrove forests, seagrass beds and coral reefs) cannot be done without understanding the direct and indirect impacts of man. The ecosystem's resilience and recovery capacity following such impacts must be determined. The efficacy of mitigation measures must also be considered. Remote sensing and geographic information systems (GIS) are excellent tools to use in such studies. This paper reviews the state of the art and application of these tools in tropical coastal zones, and illustrates their relevance in sustainable development. It highlights a selected number of remote sensing case-studies on land cover patterns, population structure and dynamics, and stand characteristics from South-East Asia, Africa and South-America, with a particular emphasis on mangroves. It further shows how remote sensing technology and other scientific tools can be integrated in long-term studies, both retrospective and predictive, in order to anticipate degradation and to take mitigating measures at an early stage. The paper also highlights the guidelines for sustainable management that can result from remote sensing and GIS studies, and identifies existent gaps and research priorities.There is a need for more comprehensive approaches that deal with new remote sensing technologies and analysis in a GIS-environment, and that integrate findings collected over longer periods with the aim of prediction. It is also imperative to collect and integrate data from different disciplines. These are essential in the spirit of sustainable development and management, particularly in developing countries, which are often more vulnerable to environmental degradation.     

供水管线震害量化参数--渗漏面积的估算方法

为了分析管线破坏状态对震后供水管网功能的影响，首先需要对管线的震害状态进行量化。建议用管线渗漏面积标定管线的破坏状态。在管线震害分析和理论计算的基础上，提出了震后管线渗漏面积的计算方法，为进一步进行供水管网抗震分析和设计提供了研究基础。     

Spatial sampling and the environment: some issues and directions

In this paper we summarize research issues for spatial environmental sampling stemming from a NISS/USEPA workshop held on 21-22 September 1994 at Chapel Hill, NC.     

氯酚与富里酸的缔合作用

本文用超滤膜方法证实氯酚与富里酸之间存在缔合作用,并计算出表观缔合常数在２．７＊１０＾３－－１２１＊１０＾３ｍｌ．ｇ＾－１范围内。实验结果表明”ＰＨ、富里酸含量,氯酚取代氯原子个数都能够影响Ｋ值的大小。     

对重庆城镇网络建设的探讨

在分析重庆直辖市城镇化现状的基础上,针对重庆城镇网络中存在的问题,依据重庆发展城镇网络的优势,提出了建立新的城镇网络扔基本思路和构想,相关的对策与建议。     

Semi-parametric statistical approaches for space-time process prediction

The problem of estimation and prediction of a spatial-temporal stochastic process, observed at regular times and irregularly in space, is considered. A mixed formulation involving a non- parametric component, accounting for a deterministic trend and the effect of exogenous variables, and a parametric component representing the purely spatio-temporal random variation is proposed. Correspondingly, a two-step procedure, first addressing the estimation of the non- parametric component, and then the estimation of the parametric component is developed from the residual series obtained, with spatial-temporal prediction being performed in terms of suitable spatial interpolation of the temporal variation structure. The proposed model formula-tion, together with the estimation and prediction procedure, are applied using a Gaussian ARMA structure for temporal modelling to space-time forecasting from real data of air pollution concentration levels in the region surrounding a power station in northwest Spain.     

基于GIS的安徽省土壤空间分布的分形特征研究

分维数和稳定性指数是土壤空间分布的重要指数。通过建立安徽省土壤的空间数据库,运用分形理论,获得安徽省土壤类型周长与面积的关系,进而计算出各类土属在空间上的分维数和稳定性指数大小,得出如下结论:①安徽省土壤图斑的周长与面积之间存在双对数函数关系,相关性系数大部分在0.9以上,证明了安徽省土壤空间分形的客观存在。②安徽省各类土壤空间分维数大小在1.1375—1.9948之间,平均值为1.6138,最大的是泥质岩砾质土,最小的是脱青湖泥田。分维数在空间分布上存在差异,总的趋势是从西北向东南逐渐变大。③各种土属的稳定性指数在1.0252—0.0124之间,平均值约为0.2324,最大的是湿潮土,最小的是砂礓黄土。     

A System for Measuring Vertical Concentration Profiles of Gaseous Pollutants,Using Carbon Dioxide as a Case Study

An electronically-controlled sampling system, characterised by its organ pipe design, has been developed for sampling air sequentially, at different heights within the breathing zone. Data are automatically logged at the different receptor levels, for the determination of the average vertical concentration profile of gaseous pollutants. The system has been coupled to a carbon dioxide monitor and used in a brief study of the spatial and temporal variation of indoor carbon dioxide concentration. The system can easily be extended for different heights or modified for use with other types of gas monitor. The results of a trial run, which was carried out in a coffee room, are presented and applications of the Organ Pipe Sequential Sampling (OPSS) system are discussed.     

Quantitative risk analysis of urban natural gas pipeline networks using geographical information systems

This paper presents a novel quantitative risk analysis process for urban natural gas pipeline networks using geographical information systems (GIS). The process incorporates an assessment of failure rates of integrated pipeline networks, a quantitative analysis model of accident consequences, and assessments of individual and societal risks. Firstly, the failure rates of the pipeline network are calculated using empirical formulas influenced by parameters such as external interference, corrosion, construction defects, and ground movements. Secondly, the impacts of accidents due to gas leakage, diffusion, fires, and explosions are analyzed by calculating the area influenced by poisoning, burns, and deaths. Lastly, based on the previous analyses, individual risks and social risks are calculated. The application of GIS technology helps strengthen the quantitative risk analysis (QRA) model and allows construction of a QRA system for urban gas pipeline networks that can aid pipeline management staff in demarcating high risk areas requiring more frequent inspections.