MULTITEMPORAL SCALE HYDROGRAPH PREDICTION USING ARTIFICIAL NEURAL NETWORKS1

Abstract: An artificial neural network (ANN) provides a mathematically flexible structure to identify complex nonlinear relationship between inputs and outputs. A multilayer perceptron ANN technique with an error back propagation algorithm was applied to a multitime-scale prediction of the stage of a hydro-logically closed lake, Devils Lake (DL), and discharge of the Red River of the North at Grand Forks station (RR-GF) in North Dakota. The modeling exercise used 1 year (2002), 5 years (1998–2002), and 27 years (1975–2002) of data for the daily, weekly, and monthly predictions, respectively. The hydrometeorological data (precipitations P_(t), P_(t-1), P_(t-2), P_(t-3), antecedent runoff/lake stage R_(t-1) and air temperature T_(t) were partitioned for training and for testing to predict the current hydro-graph at the selected DL and RR-GF stations. Performance of ANN was evaluated using three combinations of daily datasets (Input I = P_(t)), P_(t-l), P_(t-2), P_(t-3), T_(t) and R_(t-l); Input II = Input-l less P_(t) P_(t-l), P_(t-2), P_(t-3); and Input III = Input-II less T_(t)). Comparison of the model output using Input I data with the observed values showed average testing prediction efficiency (E) of 86 percent for DL basin and 46 percent for RR-GF basin, and higher efficiency for the daily than monthly simulations.     

新疆环境保护网站建设的现状与发展探讨

1997年建成的＂新疆环境保护＂网站是全国第一家环保门户网站,也是新疆第一家政府类网站,新疆环保网站建设与发展已经历风雨兼程的10a,现在正进入一个崭新的发展阶段.回顾、总结和展望新疆各级环保网站的发展,吸取发展中的经验与教训,探索新疆各级环保网站建设中的规律,对新疆环保电子政务的＂理性建设、快速推进＂大有裨益.     

RAINGAGE NETWORK DESIGN USING NEXRAD PRECIPITATION ESTIMATES1

ABSTRACT: A general framework is proposed for using precipitation estimates from NEXRAD weather radars in raingage network design. NEXRAD precipitation products are used to represent space time rainfall fields, which can be sampled by hypothetical raingage networks. A stochastic model is used to simulate gage observations based on the areal average precipitation for radar grid cells. The stochastic model accounts for subgrid variability of precipitation within the cell and gage measurement errors. The approach is ideally suited to raingage network design in regions with strong climatic variations in rainfall where conventional methods are sometimes lacking. A case study example involving the estimation of areal average precipitation for catchments in the Catskill Mountains illustrates the approach. The case study shows how the simulation approach can be used to quantify the effects of gage density, basin size, spatial variation of precipitation, and gage measurement error, on network estimates of areal average precipitation. Although the quality of NEXRAD precipitation products imposes limitations on their use in network design, weather radars can provide valuable information for empirical assessment of rain‐gage network estimation errors. Still, the biggest challenge in quantifying estimation errors is understanding subgrid spatial variability. The results from the case study show that the spatial correlation of precipitation at subgrid scales (4 km and less) is difficult to quantify, especially for short sampling durations. Network estimation errors for hourly precipitation are extremely sensitive to the uncertainty in subgrid spatial variability, although for storm total accumulation, they are much less sensitive.     

生态文明背景下物流业低碳化发展实现路径研究

物流业为碳排放量较大的行业,也是国家重点鼓励和支持的产业,实现其低碳化有利于增强行业竞争力、缓解环境问题、推动社会经济生态低碳化发展.物流业面对低碳化发展的机遇与挑战,应正视行业低碳化发展在政策和体制上存在的问题,同时需要政府健全低碳物流激励约束机制、完善物流相关基础设施;企业要有效实现共同配送和联合运输,积极推进低碳物流技术的研发与推广,完善物流信息系统,优化物流节点;社会公众形成低碳意识,支持低碳产品.     

环境生态视角下的产业共生理论与实践研究进展

产业共生是推进全球经济可持续发展的创新途径 ,主要实践载体是以高效的能源利用以及优化的资源配置特点的生态工业园区.目前产业共生研究现状中存在整体缺乏系统和深度,缺少可操作性的定量模型和评估方法及理论与产业实际过程的结合分析较少等问题,未来研究应该在总结大量产业共生实践案例的基础上,逐步建立各层面指标体系及量化方法,制定完善评价标准和综合评估技术,为生态工业园共生模式优化、共生网络稳定性和共生效率评估奠定科学依据.     

我国生态环境监测网络建设成效与展望

2015年中央全面深化改革领导小组审议通过《生态环境监测网络建设方案》,推动全国生态环境监测网络建设取得重大成就.对照《生态环境监测网络建设方案》提出的"全面设点,完善生态环境监测网络"方面的任务与要求,对生态环境监测网络建设成效进行客观评估,并对生态环境监测面临的形势与不足进行了深入剖析.针对加强生态环境监测网络建设...     

一种基于LVQ神经网络与图像处理的火焰识别算法

针对传统火灾探测技术存在的不稳定、误判率高等缺点,通过分析室内火灾图像与常见干扰光源图像的特点,提出一种基于人工神经网络的火焰图像检测技术。对火焰图像的基本特性进行分析,利用火焰图像序列的面积重叠率和中心相对移动率以及颜色等信息,结合实现学习向量量化(LVQ)神经网络融合技术,对视频序列图像中火焰的自动检测。仿真试验结果表明,基于LVQ神经网络的信息融合算法的网络收敛速度较快,有较高的火灾火焰识别准确率。     

短租民宿在线评论语义网络及感知维度研究——基于途家网和Airbnb的文本挖掘

基于途家民宿网与Airbnb在线评论信息,采用扎根理论、语义关联法与社会网络分析法定性与定量对比分析了在线评论语义网络结构特征及消费者感知维度。结果表明:①网络结构上,消费者关注焦点集中、小世界网络特征明显、社区间联系紧密。②短租民宿与传统酒店消费者感知维度在房源质量、服务态度与位置维度相似,在主客互动与装修风格上存在差异。③途家消费者更倾向于对房源进行评价,而Airbnb的主客互动性成为吸引消费者的关键因素。研究结果为短租平台从房源质量、房东素质、消费者差异化与运营模式4个方面吸引消费者提供了参考。     

Who got their way? Advocacy coalitions and the Irish climate change law

Which organisations saw their positions on two contentious issues reflected in the Irish climate law of 2015, and what role did advocacy coalitions play in the policy process? These questions are answered drawing theoretically from the Advocacy Coalition Framework (ACF) and by conducting a network analysis of survey data collected from the organisations involved in the national climate policy process. The study finds that several institutionally important or economically powerful organisations, particularly those involved in the agricultural sector, as well as the government parties saw their preferences reflected in the law. This resulted in legislation that excluded binding emission reductions targets, differentiating it from similar laws introduced in other European countries. Organisations in favour of stronger regulation formed a coalition to advocate for their positions, but they largely failed to get their way.     

太湖流域上游河流污染空间分布特征研究

为把握太湖流域上游西北部河网区域水体的N、P污染特征及其空间分布,2010年8月在该区域内的武进港 直湖港水系、洮滆水系、丹扁孟河（丹金溧漕运河、扁担河及孟津河）以及宜溧河水系的河网,监测了39个河流断面的水质。研究表明,4水系TN平均浓度分别为388、283、291及193 mg/L,DTN占TN比重分别为9180%、7843%、7001%及8444%,河网氮输出均以DTN为主。在DTN中NO-3 N浓度所占比重分别为6747%、5275%、7748%及4281%,NH+4 N浓度所占比重分别为1633%、3316%、1127%及4351%。TP平均浓度分别为059、030、026及015 mg/L,DTP所占比重分别为6213%、4019%、4673%及3197%,而PO3-4 P浓度占DTP比重分别为2073%、5461%、4327%及7772%。武进港 直湖港水系N平均浓度显著（〖WTBX〗p〖WTBZ〗<001）高于宜溧河水系,与其它两水系无显著差异,P平均浓度显著（〖WTBX〗p〖WTBZ〗<005）高于宜溧河水系和丹扁孟河,与洮滆水系无显著差异。影响太湖流域上游西北部区域河流水网水质的主导因素为氮污染,而其中以DTN污染最为严重。太湖西北部是蓝藻水华暴发的重灾区,上游区域DTN的大量输入,将成为引发太湖水体生态系统灾变的潜在风险