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1.
针对人工神经网络无法确定主要污染因子的缺陷,结合单因子评价,优化地下水水质评价模型,既可以得到客观的地下水水质综合评价等级,同时又能确定主要污染因子.利用基于人工神经网络改进的地下水水质模型对山东某水源地地下水水质进行综合评价,结果表明,该水源地地下水水质基本达到Ⅲ类水标准,满足大型供水水源地供水要求;但多数地区存在污染物超标情况,地下水中总硬度普遍偏高,有机污染物污染情况有差异.评价结果较准确地符合水体水质情况.  相似文献   

2.
针对地下水污染程度难以确定的问题,运用灰色系统理论与数值计算的方法,将对流弥散系数、渗流速度、以及衰减系数以灰参数的形式表示,建立了地下水污染的灰色数值模型,并给出了该模型的求解方法。在求解过程中,将有限差分法的截断误差进行了修正。结合地下水溶质运移问题的典型问题的示例,运用该模型进行了模拟计算。研究结果表明:在水文、水质资料较为缺乏的情况下,该模型能够模拟地下水污染的动态变化过程。  相似文献   

3.
水质评价是一个复杂的多因素评价问题.本文针对济南市地下水的实际特点,应用模糊综合评价模型,采用灰色关联度确定初始权蘑,然后根据严重超标污染因子的超标系数对初始权重进行修订的方法确定权重,对济南市地下水水质进行丁综合评价.评价结果表明:济南市地下水总体水质较好,但有的实测点存在严重的硝酸盐超标,水质为m级,评价结果与实际情况相符.  相似文献   

4.
应用人工神经网络理论与方法建立了地下水水质评价的BP神经网络模型,对涡北井田地下水水质进行了评价,并与灰色聚类结果进行了比较。结果表明,BP神经网络模型能很好地解决评价因子与水质等级间复杂的非线性关系,评价地下水水质简便可靠,预测精度高,具有通用性和客观性。  相似文献   

5.
基于灰色局势决策分析的地下水环境质量评价   总被引:10,自引:0,他引:10  
概要叙述了灰色局势决策分析的原理及其在环境质量评价中的应用方法,就阜新新邱露天煤矿排土场淋溶水对附近于家沟地区地下水环境质量的影响进行了评价研究。对研究区内的17眼水井分别采样,进行水质分析,识别出总硬度、硫酸盐、硝酸盐、氯化物、溶解性总固体、高锰酸盐指数等主要污染因子,采用灰色局势决策方法对影响区内的每个监测点位的水质进行了评价,确定出地下水环境质量的等级,并将该评价结果与模糊综合评价法、灰色关联分析法和灰色聚类分析法相比较,为污染区地下水水质的区划提供了可靠依据。  相似文献   

6.
为解决水质评价中的不相容性和模糊性等问题,在综合考虑从优隶属度和灰色关联的基础上,改进了灰色关联投影法(Grey Relation Projection Method,GRPM),将改进后的方法与投影寻踪(Projection Pursuit,PP)法相结合,提出了用于地下水水质综合评价的灰色关联投影寻踪模型.该模型把地下水水质综合评价作为一个灰色多目标决策问题,运用投影寻踪技术,构建了可以反映地下水水质状况的投影目标函数,引入萤火虫算法(Firefly Algorithm,FA)对投影目标函数进行优化,寻求灰色关联投影值的最佳投影方向,求得标准样本和评价样本的灰色关联投影值,实现了地下水水质综合评价.随机选取北京市2013年枯水期水样10例,运用该模型进行了水质综合评价,将其结果与综合评分法(F值法)结果进行比较,验证了该模型的有效性和可行性.实例应用表明,该模型评价结果可客观反映地下水水质状况,可为对比分析同一级别水质样本,分析水质变化趋势提供依据,使评价结果更趋于实际.  相似文献   

7.
地下水水质评价的人工神经网络方法   总被引:14,自引:0,他引:14  
应用人工神经网络理论与方法建立了地下水水质评价的BP神经网络模型,对涡北井田地下水水质进行了评价,并与灰色聚类结果进行了比较。结果表明,BP神经网络模型能很好地解决评价因子与水质等级间复杂的非线性关系,评价地下水水质简便可靠,预测精度高,具有通用性和客观性。  相似文献   

8.
地下水脆弱性主要是由含水层中的环境地球化学效应和包气带土壤结构效应共同作用的结果。结合采煤矿区地下水污染的实际情况,分析了地下水脆弱性的影响因素,采用数学模型和 DRASIC 评价指标体系法对矿区地下水脆弱性进行初步研究。给出了相应评价因子,建立了采煤矿区地下水水环境脆弱性评价指标体系,定量化评价地下水潜在的易污染程度,为采煤矿区的资源开采、水环境保护和地下水资源管理提供科学依据。  相似文献   

9.
地下水水质的物元评价方法及应用   总被引:3,自引:0,他引:3  
运用可拓学理论,论述了物元分析识别评判模型,建立了地下水水质评判的关联函数,为定量评价地下水水质提供了科学依据。给出了评价实例。并与地下水水质质量评价的灰色聚类方法、模糊数学方法进行了比较。  相似文献   

10.
采煤矿区地下水脆弱性评价   总被引:6,自引:1,他引:6  
地下水脆弱性主要是由含水层中的环境地球化学效应和包气带土壤结构效应共同作用的结果。结合采煤矿区地下水污染的实际情况,分析了地下水脆弱性的影响因素,采用数学模型和DRASIC评价指标体系法对矿区地下水脆弱性进行初步研究。给出了相应评价因子,建立了采煤矿区地下水水环境脆弱性评价指标体系,定量化评价地下水潜在的易污染程度,为采煤矿区的资源开采、水环境保护和地下水资源管理提供科学依据。  相似文献   

11.
Language markedness is a common phenomenon in languages, and is reflected from hearing, vision and sense, i.e. the variation in the three aspects such as phonology, morphology and semantics. This paper focuses on the interpretation of markedness in language use following the three perspectives, i.e. pragmatic interpretation, psychological interpretation and cognitive interpretation, with an aim to define the function of markedness.  相似文献   

12.
何延凌 《科技信息》2008,(4):258-258
Language is a means of verbal communication. People use language to communicate with each other. In the society, no two speakers are exactly alike in the way of speaking. Some differences are due to age, gender, statue and personality. Above all, gender is one of the obvious reasons. The writer of this paper tries to describe the features of women's language from these perspectives: pronunciation, intonation, diction, subjects, grammar and discourse. From the discussion of the features of women's language, more attention should be paid to language use in social context. What's more, the linguistic phenomena in a speaking community can be understood more thoroughly.  相似文献   

13.
There are numerous geometric objects stored in the spatial databases. An importance function in a spatial database is that users can browse the geometric objects as a map efficiently. Thus the spatial database should display the geometric objects users concern about swiftly onto the display window. This process includes two operations:retrieve data from database and then draw them onto screen. Accordingly, to improve the efficiency, we should try to reduce time of both retrieving object and displaying them. The former can be achieved with the aid of spatial index such as R-tree, the latter require to simplify the objects. Simplification means that objects are shown with sufficient but not with unnecessary detail which depend on the scale of browse. So the major problem is how to retrieve data at different detail level efficiently. This paper introduces the implementation of a multi-scale index in the spatial database SISP (Spatial Information Shared Platform) which is generalized from R-tree. The difference between the generalization and the R-tree lies on two facets: One is that every node and geometric object in the generalization is assigned with a importance value which denote the importance of them, and every vertex in the objects are assigned with a importance value,too. The importance value can be use to decide which data should be retrieve from disk in a query. The other difference is that geometric objects in the generalization are divided into one or more sub-blocks, and vertexes are total ordered by their importance value. With the help of the generalized R-tree, one can easily retrieve data at different detail levels.Some experiments are performed on real-life data to evaluate the performance of solutions that separately use normal spatial index and multi-scale spatial index. The results show that the solution using multi-scale index in SISP is satisfying.  相似文献   

14.
The discovery of the prolific Ordovician Red River reservoirs in 1995 in southeastern Saskatchewan was the catalyst for extensive exploration activity which resulted in the discovery of more than 15 new Red River pools. The best yields of Red River production to date have been from dolomite reservoirs. Understanding the processes of dolomitization is, therefore, crucial for the prediction of the connectivity, spatial distribution and heterogeneity of dolomite reservoirs.The Red River reservoirs in the Midale area consist of 3~4 thin dolomitized zones, with a total thickness of about 20 m, which occur at the top of the Yeoman Formation. Two types of replacement dolomite were recognized in the Red River reservoir: dolomitized burrow infills and dolomitized host matrix. The spatial distribution of dolomite suggests that burrowing organisms played an important role in facilitating the fluid flow in the backfilled sediments. This resulted in penecontemporaneous dolomitization of burrow infills by normal seawater. The dolomite in the host matrix is interpreted as having occurred at shallow burial by evaporitic seawater during precipitation of Lake Almar anhydrite that immediately overlies the Yeoman Formation. However, the low δ18O values of dolomited burrow infills (-5.9‰~ -7.8‰, PDB) and matrix dolomites (-6.6‰~ -8.1‰, avg. -7.4‰ PDB) compared to the estimated values for the late Ordovician marine dolomite could be attributed to modification and alteration of dolomite at higher temperatures during deeper burial, which could also be responsible for its 87Sr/86Sr ratios (0.7084~0.7088) that are higher than suggested for the late Ordovician seawaters (0.7078~0.7080). The trace amounts of saddle dolomite cement in the Red River carbonates are probably related to "cannibalization" of earlier replacement dolomite during the chemical compaction.  相似文献   

15.
王慧 《科技信息》2008,(10):240-240
Wuthering Heights, Emily Bronte's only novel, was published in December of 1847 under the pseudonym Ellis Bell. The book did not gain immediate success, but it is now thought one of the finest novels in the English language. Catherine is the key character of this masterpiece, because everybody and everything center on her though she had a short life. We can understand this masterpiece better if we know Catherine well.  相似文献   

16.
The Williston Basin is a significant petroleum province, containing oil production zones that include the Middle Cambrian to Lower Ordovician, Upper Ordovician, Middle Devonian, Upper Devonian and Mississippian and within the Jurassic and Cretaceous. The oils of the Williston Basin exhibit a wide range of geochemical characteristics defined as "oil families", although the geochemical signature of the Cambrian Deadwood Formation and Lower Ordovician Winnipeg reservoired oils does not match any "oil family". Despite their close stratigraphic proximity, it is evident that the oils of the Lower Palaeozoic within the Williston Basin are distinct. This suggests the presence of a new "oil family" within the Williston Basin. Diagnostic geochemical signatures occur in the gasoline range chromatograms, within saturate fraction gas chromatograms and biomarker fingerprints. However, some of the established criteria and cross-plots that are currently used to segregate oils into distinct genetic families within the basin do not always meet with success, particularly when applied to the Lower Palaeozoic oils of the Deadwood and Winnipeg Formation.  相似文献   

17.
理论推导与室内实验相结合,建立了低渗透非均质砂岩油藏启动压力梯度确定方法。首先借助油藏流场与电场相似的原理,推导了非均质砂岩油藏启动压力梯度计算公式。其次基于稳定流实验方法,建立了非均质砂岩油藏启动压力梯度测试方法。结果表明:低渗透非均质砂岩油藏的启动压力梯度确定遵循两个等效原则。平面非均质油藏的启动压力梯度等于各级渗透率段的启动压力梯度关于长度的加权平均;纵向非均质油藏的启动压力梯度等于各渗透率层的启动压力梯度关于渗透率与渗流面积乘积的加权平均。研究成果可用于有效指导低渗透非均质砂岩油藏的合理井距确定,促进该类油藏的高效开发。  相似文献   

18.
In the 19th century the society was controlled by men, and women were just appendants of them, they had not any rights and freedom. But Jane was an exception, she showed some characteristics of early feminist. Jane showed her characteristics of feminism in three aspects: rebellion, equality, and independence. These characteristics were helpful to her success, and feminism is the only way out for women of that time.  相似文献   

19.
As an American modern novelist who were famous in the literary world, Hemingway was not a person who always followed the trend but a sharp observer. At the same time, he was a tragedy maestro, he paid great attention on existence, fate and end-result. The dramatis personae's tragedy of his works was an extreme limit by all means tragedy on the meaning of fearless challenge that failed. The beauty of tragedy was not produced on the destruction of life, but now this kind of value was in the impact activity. They performed for the reader about the tragedy on challenging for the limit and the death.  相似文献   

20.
AcomputergeneratorforrandomlylayeredstructuresYUJia shun1,2,HEZhen hua2(1.TheInstituteofGeologicalandNuclearSciences,NewZealand;2.StateKeyLaboratoryofOilandGasReservoirGeologyandExploitation,ChengduUniversityofTechnology,China)Abstract:Analgorithmisintrod…  相似文献   

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