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491.
Abstract A one-dimensional water quantity and quality mathematical model was developed to evaluate the effects of joint gate–pump operation in terms of water withdrawal for pollutant flushing. The study was carried out in dry seasons in the Foshan River channel, China. The results indicate that the input of freshwater into the upper and middle reaches of the Foshan River can improve the water quality of the lower reaches. However, the backwater effect due to water diversion in the middle reaches of the river can greatly offset the cleaning processes in the upper reaches of the Foshan River. The results indicate that water quality in the upper Foshan River (Jiebian) may degrade with an increase in the rate of water withdrawal from the middle river when the discharge pumped from the upper Foshan River is less than 10m3/s; optimal water quality improvement is obtained with discharge values of 30 and 20 m3/s, respectively, at the upper and middle reaches of the Foshan River. Editor D. Koutsoyiannis Citation Liu, C.-L., Jiang, T., Zhang, Q., Zhu, S. and Li, K., 2012. Modelling of water withdrawal for pollutant flushing in the tidal river network, Pearl River Delta, China. Hydrological Sciences Journal, 57 (3), 576–590. 相似文献
492.
图形数据与关系数据库的结合及其应用 总被引:46,自引:2,他引:44
将空间图形数据存入关系型数据是当前数据库和地理信息系统领域研究的热点和前沿,本文提出了一种将空间图形数据存入关系型数据库的数据模型,分析了数据模型的数据组织操作,空间图形要素表达以及数据模型体系结构,根据该结构模型,实现了在SQL Server关系型数据库中对空间图形数据进行存储、拓扑运算和拓扑分析的操作,最后,给出了一个采用该结构模型实现的基于SQL Server数据库平台的精简型空间数据库引擎Spatial DatlbaseGuide软件产品,及其在土地产权产籍信息系统领域的应用实例。 相似文献
493.
Flushing sediment through a reservoir has been practiced successfully and found to be inexpensive in many cases. However, the great amount of water consumed in the flushing operation might affect the water supply. To satisfy the water demand and water consumed in the flushing operation, two models combining the reservoir simulation model and the sediment flushing model are established. In the reservoir simulation model, the genetic algorithm (GA) is used to optimize and determine the flushing operation rule curves. The sediment‐flushing model is developed to estimate the amount of the flushed sediment volume, and the simulated results update the elevation‐storage curve, which can be taken into account in the reservoir simulation model. The models are successfully applied to the Tapu reservoir, which has faced serious sedimentation problems. Based on 36 years historical sequential data, the results show that (i) the simulated flushing operation rule curves model has superior performance, in terms of lower shortage index (SI) and higher flushing efficiency (FE), than that by the original reservoir operation; (ii) the rational and riskless flushing schedule for the Tapu reservoir is suggested to be set within an interval of every 2 or 4 years in the months of May or June. Copyright © 2003 John Wiley & Sons, Ltd. 相似文献
494.
“江南工程项目管理模式”是广州中煤江南基础工程公司从长期施工实践中总结、归纳、提升出来的工程项目管理模式。其主要内容包括自主经营管理、项目预算管理、工程质量管理、安全生产管理和文明施工管理五个子模式。该模式的五大管理子模式,是一个有机的整体,涵盖了工程项目管理的基本内容,贯穿于工程项目管理的全过程,其内容具体明确,可操作性强。“江南工程项目管理模式”在广州市猎德村改造基坑工程项目中的典范应用,表明该模式的推行,对于提高企业的管理水平,增强企业市场竞争能力具有十分重大的现实意义。 相似文献
495.
496.
宋晓红 《测绘与空间地理信息》2014,(9):140-141
地理国情普查(监测)和1∶10 000 DLG更新协同作业模式,无论是内业编辑处理,还是外业调绘核查同步进行,既降低了生产成本,又提高了生产效率,是一种新工艺流程的探索。 相似文献
497.
498.
智利小规模采选业因分布分散且缺乏相应的环保技术与资金投入,其对环境造成了一定的影响。在智利法律系统监管和支持下,该小规模采选业得到有序发展。同时,小规模金属采选业与智利法律规定的大中型矿产开发项目须完成试验性工业开采(即小规模开发实验)存在一定联系。本文通过调查智利中北部第三、第四和第六区小型开采规模的铜、金和银矿山,分析其生产经营过程中对环境的潜在影响因素,剖析小规模金属选场对智利环境带来的影响,总结金属矿小规模采选业的规范性运营方式,找出法律规定与产业运营的内在联系。建议我国企业在智利进行矿产勘探和可行性研究中重视小规模采选试验与规模性勘查工作的合理有序结合。 相似文献
499.
500.
A mobile laser scanning (MLS) system allows direct collection of accurate 3D point information in unprecedented detail at highway speeds and at less than traditional survey costs, which serves the fast growing demands of transportation-related road surveying including road surface geometry and road environment. As one type of road feature in traffic management systems, road markings on paved roadways have important functions in providing guidance and information to drivers and pedestrians. This paper presents a stepwise procedure to recognize road markings from MLS point clouds. To improve computational efficiency, we first propose a curb-based method for road surface extraction. This method first partitions the raw MLS data into a set of profiles according to vehicle trajectory data, and then extracts small height jumps caused by curbs in the profiles via slope and elevation-difference thresholds. Next, points belonging to the extracted road surface are interpolated into a geo-referenced intensity image using an extended inverse-distance-weighted (IDW) approach. Finally, we dynamically segment the geo-referenced intensity image into road-marking candidates with multiple thresholds that correspond to different ranges determined by point-density appropriate normality. A morphological closing operation with a linear structuring element is finally used to refine the road-marking candidates by removing noise and improving completeness. This road-marking extraction algorithm is comprehensively discussed in the analysis of parameter sensitivity and overall performance. An experimental study performed on a set of road markings with ground-truth shows that the proposed algorithm provides a promising solution to the road-marking extraction from MLS data. 相似文献