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水环境质量评价可以为水环境治理工作和规划提供科学的决策依据。综合考虑水环境系统的模糊性及随机性,建立了基于云模型的评价方法,以贾鲁河郑州段2017年水环境监测资料为依据,选取COD、氨氮、总磷为评价指标,运用超标倍数赋权法确定权重,利用正、逆向云算法得到单指标的云模型,并通过综合确定度对水环境质量进行综合评价。研究表明:云模型能够很好地实现检测数值和评价等级之间的转换;2017年1-2月该地区水质为劣Ⅴ类,3-11月水质明显提高,水环境质量呈现逐月好转的趋势,且评价结果与实际情况相符。 相似文献
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BP网络、Hopfield网络在水质评价应用中的比较研究 总被引:1,自引:0,他引:1
针对BP网络、Hopfield网络在水质评价的应用问题,建立BP网络、Hopfield网络水质评价模型,对BP网络、Hopfield网络从结构、输入输出、稳定性、评价结果等方面进一步地分析比较。然后以东辽河为例,运用BP网络、Hopfield网络、模糊评价法、内梅罗指数法4种水质评价方法进行水质评价,通过比较评价结果进行深入研究。结果表明,Hopfield神经网络更适用于水质评价。对神经网络方法水质评价问题进行探讨,试图找出BP网络、Hopfield网络方法在水质综合评价中的优缺点,具有非常现实的意义。 相似文献
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针对面板数据灰色关联决策分析评价问题,在经典灰色关联分析和灰色综合评价方法的基础上,构建面板数据灰色关联决策评价模型。将灰色关联决策方法扩展到面板数据分析中,解决了小样本面板数据的灰色评价分析问题。将这种方法应用于水环境面板数据质量评价中,经实例计算验证了面板数据灰色关联决策评价模型的稳定性、合理性和实用性,为水环境面板数据质量分析评价提供了可行的计算思路和方法。 相似文献
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《节水灌溉》2014,(6)
为了解BP神经网络模型在水质评价上的适用性,以黄河流域小浪底济源断面2010-2013年4个水质指标pH值、DO、COD、NH3-N为评价研究对象,结合统计软件MATLAB,以2010-2012年水质指标为训练集,2013年水质指标为检验预测集,通过输入变量和输出变量的确定以及隐层节点数的选择,确定最优的模型拓扑结构,构建单隐层BP神经网络模型。结果表明,BP神经网络模型评价水质结果同综合污染指数法评价水质结果基本吻合,BP神经网络训练结果吻合率达到93.33%。通过实例分析表明,该模型应用于水质评价具有客观性和实用性,经过训练的模型能够准确评价黄河流域水体的水质类别,模型具有较好的评价效果。 相似文献
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《农机化研究》2021,43(6)
对棚内温度进行精确预测是实现棚室精准调控的前提,是实现棚内作物高品质栽培的保障。因棚室具有大惯性、强耦合、非线性等特点,通过机理分析法难以建立其准确的数学模型,人工神经网络方法在棚室温度预测方面应用广泛,但其存在的收敛速度慢、容易陷入局部最小等缺点使测量精度受到影响。为进一步提高基于神经网络算法的棚室温度预测模型精度,运用思维进化算法(Mind Evolutionary Algorithm,MEA)优化LM-BP神经网络模型的输入权重和阈值,并与遗传算法优化LM-BP网络模型和LM-BP模型进行对比。试验结果表明:MEA-LM-BP与LM-BP和GA-LM-BP方法相比,RMSE分别降低了0.32和0.16,平均相对误差降低了1.08%和0.58%。该方法提高了基于神经网络算法的棚室温度预测模型精确度,并提供了新的优化路径。 相似文献
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首先介绍了BP神经网络和LM-BP神经网络的原理,然后介绍了采摘机器人运动学模型,最后采用LM-BP神经网络实现了采摘机器人智能运动策略。MatLab仿真表明:对于不同的果树种植布局及不同的起点和终点,采摘机器人采用该算法均能产生可行的无碰撞路径,以顺利完成采摘作业。 相似文献
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随着经济发展、人民生活水平提高及城市化进程加速,我国畜禽产品的市场需求也不断增加,畜禽养殖业生产规模不断扩大,由此而带来的环境污染问题也日趋严重.本研究针对我国集约化猪场废水处理项目在立项、建设中,技术、经济、环境评价方法尚不完善的现状,编制出猪场废水处理及资源化利用模型.该模型在给定饲养规模、废水量及浓度、拟定废水处理目标等基本信息基础上,能够提供猪场废水处理工程工艺方案比较、机械设备选型参数、构筑物设计参数、处理效果、投资估算及运行费用计算,快速完成初步方案的设计. 相似文献
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A. Akramkhanov R. Sommer C. Martius J. M. H. Hendrickx P. L. G. Vlek 《Irrigation and Drainage Systems》2008,22(1):115-126
In Khorezm, a district of Uzbekistan situated in the Aral Sea Basin, soil salinization is an important driver of soil degradation
in irrigated agriculture. The main objective of this study was to identify techniques that enable rapid estimation of soil
salinity. Therefore, bulk electrical conductivity of the soil (ECa-meas) was measured with three different devices (2P, 4P, and CM-138) and electrical conductivity of the soil paste (ECp-meas) was measured with the so-called 2XP device. These measurements were compared with independent estimates of ECa-calc and ECp-calc based on laboratory measurements of the saturated extract, ECe, of soil samples from the same sites. Soil salinity could be assessed satisfactorily with all four devices. ECp-meas could be well reproduced by the 2XP device (R
2 = 0.76), whereas ECa-meas estimates using 2P, 4P, and CM-138 in the field were less accurate (R
2 < 0.50). The sensitivity of all devices to the main ions Cl− and Ca2 + suggests that the measuring principles are similar for all instruments. The devices can therefore be used interchangeably.
Field assessment of soil salinity was considerably enhanced by the use of CM-138, because large areas can be quickly assessed,
which may be desirable in spite of the lower accuracy. 相似文献
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为弥补现有水质评价方法的不足之处,采用免疫进化算法优化投影寻踪模型的投影方向,提出基于免疫进化算法的投影寻踪模型,并将模型运用于我国五大湖水质评价及各种富营养化指标对湖泊富营养化程度评价的影响。结果表明通过比较基于免疫进化算法的投影寻踪水质评价模型的最佳投影方向各分量的大小和投影值的大小即可确定水体中污染物的主次及治理的优先并实现同类水之间的水质优劣比较;该模型能将高维数据通过最佳投影方向映射到低维子空间,便于对样本进行分类和综合评价,为水质评价研究领域提供了新的思路和方法。 相似文献
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水资源合理配置研究是水资源规划与管理中的关键部分。基于河北省南水北调供水区水资源系统特征,建立了多目标、多水源、多用户的水资源合理配置模型,并采用大系统分解协调技术与目标逼近技术相结合方法对所建立的模型进行求解,同时考虑供水区水资源配置方案的经济、社会和生态环境影响,建立水资源配置方案评价指标体系,采用模糊物元分析方法对方案进行了综合评价,取得了合理配置方案,并对推荐方案进行了综合分析。该研究为供水区水资源可持续发展提供了参考。 相似文献
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A rational method for assessing irrigation performance at farm level with the aid of fuzzy set theory 总被引:1,自引:0,他引:1
Of the various client groups with interests in irrigation system performance, farmers are probably the least often considered. This is, at least in part, attributable to the profound difficulty encountered in attempting to obtain reliable measurements of performance at farm level in most systems. Yet irrigation systems should be seen as a service to farmers, whose perspective on the utility of the supply is an important component of performance monitoring. Direct measurement at field level is generally not feasible and an alternative approach is proposed utilising fuzzy set theory. The procedure can be seen as a rapid appraisal technique which is also applicable to performance assessment in informal farmer-managed systems. The usefulness of the approach lies in its ability to gather data in imprecise linguistic terms from individual farmers and to aggregate them rationally and objectively. 相似文献
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A comprehensive framework for conceptualizing irrigation performance is presented which, by clarifying relationships among the many incommensurate approaches to performance assessments, can provide the basis for more systematic comparative assessments of irrigation. Irrigation systems are carefully defined, and their relationships to broader agricultural and socioeconomic systems specified in terms both of goals and of inputs and outputs. Goals are seen as crucial to performance assessments, and the existence of many sometimes conflicting goals requires both specification of whose goals are being considered and clarification as to whether the goals are related to inputs, to outputs or to efficiency. Assessments can be categorized according to their purpose, with significant differences among those that monitor operational performance, those that facilitate interventions to improve performance, and those that promote accountability within an operating agency. Assessments also differ in the types of performance measures used. Three distinct categories of performance measures are identified: process measures, which relate to a system's internal operations; output measures, which focus on a system's final output; and impact measures, which pertain to the effects that the system's outputs induce in its larger environment. Performance measures are distinguished from performance standards which may be established from a variety of sources.Earlier versions of this paper were presented at the Symposium on Performance Evaluation of Irrigation systems held at the International Irrigation Management Institute, Colombo, Sri Lanka on November 23, 1989, and at a Workshop on Irrigation Performance held in Pangbourne, England, February 15–16, 1990. 相似文献
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大坝安全风险评估初探 总被引:4,自引:0,他引:4
根据风险理论在其它领域的应用实践,以及大坝安全风险管理在国外的应用经验,将大坝安全风险评估的原理、实施步骤等进行了阐述,探讨了大坝风险因素、失事树分析法及事件概率计算方法等诸多关键问题,并通过算例对文中所探讨的问题进行了较为明确的应用与说明。 相似文献