共查询到19条相似文献,搜索用时 171 毫秒
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基于模糊聚类与神经网络的柴油机技术状态评价方法研究 总被引:1,自引:0,他引:1
对在正常工作条件下不同使用时间的某型装甲车辆柴油机进行了实车测试试验,提取了评价柴油机技术状态的特征向量;阐述了模糊聚类和神经网络的原理;根据技术状态不同,利用模糊聚类的方法将所测柴油机分成了5类,将分类结果作为神经网络模型训练样本理想输出值的确定依据;利用RBF-BP组合神经网络建立了基于多参数测试的柴油机技术状态评价模型,并对部分柴油机进行了技术状态评价.结果表明,神经网络评价结果与分类结果是一致的,基于神经网络的技术状态评价模型具有推广应用价值. 相似文献
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针对唐山市地域特征和水安全现状,采用压力一状态一响应模型(PSR)建立了唐山市水安全评价指标体系,利用层次分析法确定各指标权重,对唐山市2004~2012年水安全状况进行综合评价,并在此基础上利用灰色系统模型GM(1,1)对唐山市2013~2020年的水安全状况进行预测。结果表明,唐山市2005~2009年的水安全状况处于基本安全状态,2012年水安全状况转为安全,但仍在安全与不安全状态的边缘波动,2013~2020年城市水安全状况会逐渐好转,但压力、状态、响应因子呈现不同的变化幅度,说明人类社会经济活动对水环境的影响较大,仍需加大水环境保护投资和水环境污染治理力度,提高水资源承载力才能形成生态环境与社会经济和谐发展的局面,从而确保城市用水安全。 相似文献
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为科学处理土石坝安全评价过程中的模糊性和灰色性问题,基于模糊最优最劣法(FBWM)及灰色聚类法,构建土石坝安全评价模型。通过查阅资料及咨询相关专家,确定评价指标中的最优指标及最劣指标,引入FBWM法计算各评价指标的权重;分析相关安全监控仪器实测资料,进而构建灰色聚类权重矩阵;将评价指标权重矩阵与灰色聚类权重矩阵相结合,得到土石坝的安全评价结果。将该模型应用于某土石坝的安全评价,结果表明该土石坝处于"基本正常"运行状态,与实际情况相符。可见该方法结论可靠,可以为土石坝的状态诊断提供决策支持。 相似文献
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为助力“双碳”目标实现,推动风电产业发展,研究并治理风电场并网宽频振荡问题迫在眉睫。为建立适用于风电场振荡研究且能准确高效反映实际风电场输出特性的仿真模型,提出基于模糊度量的层次聚类法,改善传统综合层次聚类算法使用距离度量造成的聚类结果偏移。利用F检验法定量评价聚类效果,横向比较F评分确定最优聚类方案,纵向比较确定最优聚类分群数。评价结果表明,模糊度量层次聚类法的聚类效果良好。最后采用PSCAD结合青海省海南新能源基地风电场实例进行了仿真分析,验证了模糊度量层次聚类法对风电场聚类的适用性。 相似文献
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为提高长江经济带水资源利用效率,促进工业经济增长与水资源协同发展,将水环境污染作为非期望产出,首先基于SBM模型与GML生产率指数测算2005~2015年长江经济带11个省市与上、中、下游3大区域的工业水资源效率与工业水资源全要素生产率,并考察其时空异质性;进而根据工业水资源全要素生产率的分解结果,揭示出各省市工业水资源效率提升的驱动因素;最后,通过构建效率-生产率方阵综合分析各省市水污染防治的优势与不足。结果表明,考察期内,长江经济带工业水资源效率较低,地区差异显著,下游明显优于中上游;技术效率变化和技术进步对全要素生产率提升的影响是负向的,且技术进步是主要障碍;各省市工业水资源绩效呈现"马太效应"特征,落后省市与先进省市之间的差距将拉大。研究成果可为长江经济带发展决策提供参考。 相似文献
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针对电力大数据流的异常检测问题,该文将流数据聚类算法与电力大数据相结合,针对现有流数据聚类算法不易存储全部数据、断电数据易丢失等问题,以及流数据聚类算法对于离线阶段聚类算法实时应答的要求,从数据的完整性、安全性以及流数据聚类算法的低时间复杂度的角度出发,对CluStream流数据聚类算法进行改进,提出流式K-means聚类算法。对在线阶段,使用Redis集群进行流数据的缓冲,并设计节点时间衰减策略,增大心跳消息中有效消息所占比例;对离线阶段聚类算法进行优化,使用最佳距离法确定初始聚类中心,减少迭代次数;最后,使用所提出的流式K-means聚类算法进行用户用电异常行为检测,实验结果表明,该算法能够很好的发现用户用电异常行为。 相似文献
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The imbalance of heat extracted from the earth by the underground heat exchangers in winter and ejected into it in summer is expected to affect the long term performance of conventional ground source heat pump (GSHP) in territories with a cold winter and a warm summer such as the middle and downstream areas of the Yangtze River in China. This paper presents a new multi-function ground source heat pump (MFGSHP) system which supplies hot water as well as space cooling/heating to mitigate the soil imbalance of the extracted and ejected heat by a ground source heat pump system. The heat transfer characteristic is studied and the soil temperature around the underground heat exchangers are simulated under a typical climatic condition of the Yangtze River. A three-dimensional model was constructed with the commercial computational fluid dynamics software FLUENT based on the inner heat source theory. Temperature distribution and variation trend of a tube cluster of the underground heat exchanger are simulated for the long term performance. The results show that the soil temperature around the underground tube keeps increasing due to the surplus heat ejected into the earth in summer, which deteriorates the system performance and may lead to the eventual system deterioration. The simulation shows that MFGSHP can effectively alleviate the temperature rise by balancing the heat ejected to/extracted from underground by the conventional ground source heat pump system. The new system also improves the energy efficiency. 相似文献
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Kaiyuan He 《Combustion and Flame》2008,155(4):585-604
An effective adaptive mechanism reduction approach based on flux graph clustering is proposed in this paper. The instantaneous element flux is quantified and considered as a proxy for describing the reactive propensities of the system. Our underlying hypothesis is that even though particular conditions may be characterized by a multitude of combinations of species mass fraction, T, and P, the essential chemistry, and hence the reaction propensity of the mixture that is active under this family of conditions, is the same. Therefore, we opt to use the instantaneous fluxes through the active reactions as an intrinsic property of the system. Flux graphs are first constructed for the chemical reaction system under numerous conditions aiming at capturing the attainable region. Similarity between flux graphs is quantified through the distances between corresponding vectors, using the cosine coefficient and a novel graph-distance metric taking into account the magnitude of each flux and the activity distribution of different fluxes. A hierarchical clustering algorithm is implemented to group similar instantaneous flux graphs into clusters, and consequently a reduced mechanism is generated for each cluster. A search algorithm is defined afterward to assign a new query point to a particular flux graph cluster, and subsequently the reduced mechanism associated with this cluster is used to describe the system at this time point. Finally, the methodology is demonstrated using n-pentane combustion in an adiabatic plug flow reactor model and a pairwise mixing stirred reactor model. 相似文献
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Ruiming Fang Rongyan Shang Minling Wu Changqing Peng Xinhua Guo 《International Journal of Hydrogen Energy》2017,42(31):20154-20163
Considering the characteristics of dynamic gray correlation among operational conditions of wind turbines, an innovative clustering method for dynamic equivalent modeling of wind farms (WFs) based on the dynamic gray cluster algorithm is proposed. The proposed method is used to determine the number and composition of equivalent wind turbine (WT) groups that can be used to represent a WF. Based on an analysis of auto-correlation coefficients among the various monitoring items of a supervisory control and data acquisition (SCADA) system for a WT, the time span of clustering samples is determined. Then, a correlation matrix of the clustering samples is constructed by using the dynamic gray relational analysis method. Finally, WTs are divided into groups by analyzing the abovementioned correlation matrix by using the k-means clustering algorithm, and WTs belonging to the same group are considered equivalent to one turbine to realize dynamic equivalent modeling of WFs. The method is demonstrated on a WF comprising 22 WTs connected to an IEEE 39 bus test system. Dynamic responses of the proposed model for the WF are compared against the response of the detailed model and other models for various scenarios. The comparison results show that the proposed dynamic equivalent model can describe the dynamic response characteristics of a WF with accuracy similar to that of the detailed model, and the proposed model is simpler and has lower computational complexity. 相似文献