Time Series Forecasting of Cyanobacteria Blooms in the Crestuma Reservoir (Douro River, Portugal) Using Artificial Neural Networks

In this work, time series neural networks were used to predict the occurrence of toxic cyanobacterial blooms in Crestuma Reservoir, which is an important potable water supply for the Porto region, located in the north of Portugal. These models can potentially be used to provide water treatment plant operators with an early warning for developing cyanobacteria blooms. Physical, chemical, and biological parameters were collected at Crestuma Reservoir from 1999 to 2002. The data set was then divided into three independent time series, each with a fortnightly periodicity. One training series was used to “teach” the neural networks to predict results. Another series was used to verify the results, and to avoid over-fitting of the data. An additional independently collected data series was then used to test the efficacy of the model for predicting the abundance of cyanobacteria. All of the models tested in this study incorporated a prediction time (look-ahead parameter) equal to the sampling interval (two weeks). Various lag periods, from 2 to 52 weeks, were also investigated. The best model produced in this study provided the following correlations between the target and forecast values in the training, verification, and validation series: 1.000 (P = 0.000), 0.802 (P = 0.000), and 0.773 (P = 0.001), respectively. By applying this model to the three-year data set, we were able to predict fluctuations in cyanobacteria abundance in the Crestuma Reservoir, with a high level of precision. By incorporating a lag-period of eight weeks, we were able to detect secondary fluctuations in cyanobacterial abundance over the annual cycle.     

关于构建珠江三角洲生态工业网络的思考——以中山市为例

本文简要介绍了生态工业园的理论与实践进展,在分析珠江三角洲工业经济发展现状的基础上,以中山市为例,对如何构建区域生态工业网络、建立企业生态链条、完善管理机制作了探讨。作者认为,构建珠江三角洲区域生态工业网络是必要的和可行的,但应注意以下几点：宏观上,进行合理布局,重点考虑入网行业、地理分布、试点行业和园区;微观上,解决如何更好地构筑企业共生体和生态工业链、提高生态工业网络的竞争力和稳定性等关键问题;管理上,注意完善机制,建立有效的内部管理机构、保证充分的信息沟通;在政府层面上,充分发挥政策的支持和引导作用等,以保证生态工业网络稳定运行。     

Inventories and maps: cognitive ways of framing the nature policies in Europe

Since the Earth Summit in Rio, declining biodiversity has become a subject of general concern for many countries. To counter these negative trends, government nature policies in Europe at least are now thought out primarily in terms of networks. They concern new areas outside nature reserves, new players and new management strategies. Consequently, these policies should themselves become the subject of new public debate. Our study concerns the analysis of the forms used to collect the data required to set up the European Union's Natura 2000 network and maps drawn as part of the Council of Europe's Pan-European Ecological Network strategy. The aim of this article, which takes the perspective developed by the sociology of science, will be to show how the forms and maps used in these new nature policies produce knowledge that precedes policy discussions to search for the best possible socio-political compromises. In other words, the knowledge that is collected in and by means of these documents, forms and maps offers a cognitive way of ‘framing’ the subsequent public debates. Copyright © 2002 John Wiley & Sons, Ltd.     

AN APPLICATION OF NETWORK THEORY TO WATER MANAGEMENT IN POULTRY PROCESSING1

ABSTRACT This paper summarizes a study employing a systems approach for analyzing one class of modifications within a poultry processing plant. The modifications considered were changes in water-flow arrangements and process characteristics to reduce water intake of the plant and waste-treatment costs. The object of the study was to develop a technique or techniques by which a combination of proposed modifications could be chosen to minimize water flow through the plant. Existing and proposed flows were represented as a network, and linear programming was used to solve the minimum-flow problem for the network. Application of the technique was made to an existing, typical plant in Durham, N.C. Results of the application showed fresh water intake could be reduced by 45% to 51%, and furthermore that annual returns of 62% to 494% could be obtained on investment in the optimum modification sets, as fresh water costs varying from 10 cents to $1.00 per 1000 gal. Types of modifications of a poultry processing plant are classified by types, and the relative importance and effectiveness of each type are discussed.     

ON PRECIPITATION SENSOR NETWORK DENSITIES FOR EVALUATING WINTERTIME OROGRAPHIC CLOUD SEEDING EXPERIMENTS1

Principal component analysis is used to investigate density requirements of wintertime orographic cloud seeding experiment precipitation sensor networks. Three passes in the vicinity of Climax, Colorado are studied. The eighteen or more evenly spaced precipitation sensors of each pass are almost completely described by three principal components. These three principal components appear to represent (i) mean precipitation, (ii) slope orientation to storm systems, and (iii) elevation. Evaluation of these principal components is implemented with two distribution-free tests, a proportionality test and the runs test. The results of this study suggest that the loss of experimental information caused by low density precipitation sensor networks may be of little consequence.     

AUTOMATED EXTRACTION OF DRAINAGE NETWORK AND WATERSHED DATA FROM DIGITAL ELEVATION MODELS1

ABSTRACT: This paper discusses a computer program which extracts a number of watershed and drainage network properties directly from digital elevation models (DEM) to assist in the rapid parameterization of hydrologic runoff models. The program integrates new and established algorithms to address problems inherent in the analysis low-relief terrain from raster DEMs similar to those distributed by the U.S. Geological Survey for 7.5-minute quadrangles. The program delineates the drainage network from a DEM, and determines the Strahler order, total and direct drainage area, length, slope, and upstream and downstream coordinates of each channel link. It also identifies the subwatershed of each channel source and of the left and right bank of each channel link, and assigns a unique number to each network node. The node numbers are used to associate each subwatershed with the channel link to which it drains, and can be used to control flow routing in cascade hydrologic models. Program output includes tabular data and raster maps of the drainage network and subwatersheds. The raster maps are intended for import to a Geographical Information System where they can be registered to other data layers and used as templates to extract additional network and subwatershed information.     

基于遥感的洪水灾害承灾体神经网络的提取方法探讨

洪水灾害承文体信息的快速获取是洪水灾害评估的基础．卫星遥感所获得的遥感图象包含了有关该承灾体的空间分布信息．常规目视解译难以快速并准确地从遥感图象中提取这些信息．神经网络技术的发展为解决这一问题提供了新的工具．本文阐这了将神经网络用于从遥感图象中自动提取洪水灾害承文体的空间分布信息的基本原理和方法,并结合实例说明了这种方法的有效性     

基于遗传算法的洪水灾情评估神经网络模型探讨

洪水灾情评估实际上是一种模式识别问题,而人工神经网络模型具有逼近有界闭子集上任意非线性映射的特性,且模型更新方便。本文邮基于遗传算法的洪水灾情评估神经网络模型,阐述了其基本原理和算法,实例研究表明其实用性、客观性和通用性。     

Adjusted two-stage adaptive cluster sampling

An adjusted two-stage sampling procedure is discussed for adaptive cluster sampling where some networks are large and others are small. A two-stage sample is drawn from the large networks and a single-stage sample is drawn from the rest. The simple random sampling (SRS) procedure without replacement is used at the initial stage. An estimator for the population mean along with its properties is discussed.     

论大学生思想政治工作进网络之紧迫性

在对大学生利用网络的情况进行调查的基础上，总结出学生使用网络的现实基本状况，并分析学生上网存在的问题，指出学院的思想政治工作进网络的紧迫性。