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An evaluation method of contribution rate based on fuzzy Bayesian networks for equipment system-of-systems architecture
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作者 XU Renjie LIU Xin +2 位作者 CUI Donghao XIE Jian GONG Lin 《Journal of Systems Engineering and Electronics》 SCIE EI CSCD 2023年第3期574-587,共14页
The contribution rate of equipment system-of-systems architecture(ESoSA)is an important index to evaluate the equipment update,development,and architecture optimization.Since the traditional ESoSA contribution rate ev... The contribution rate of equipment system-of-systems architecture(ESoSA)is an important index to evaluate the equipment update,development,and architecture optimization.Since the traditional ESoSA contribution rate evaluation method does not make full use of the fuzzy information and uncertain information in the equipment system-of-systems(ESoS),and the Bayesian network is an effective tool to solve the uncertain information,a new ESoSA contribution rate evaluation method based on the fuzzy Bayesian network(FBN)is proposed.Firstly,based on the operation loop theory,an ESoSA is constructed considering three aspects:reconnaissance equipment,decision equipment,and strike equipment.Next,the fuzzy set theory is introduced to construct the FBN of ESoSA to deal with fuzzy information and uncertain information.Furthermore,the fuzzy importance index of the root node of the FBN is used to calculate the contribution rate of the ESoSA,and the ESoSA contribution rate evaluation model based on the root node fuzzy importance is established.Finally,the feasibility and rationality of this method are validated via an empirical case study of aviation ESoSA.Compared with traditional methods,the evaluation method based on FBN takes various failure states of equipment into consideration,is free of acquiring accurate probability of traditional equipment failure,and models the uncertainty of the relationship between equipment.The proposed method not only supplements and improves the ESoSA contribution rate assessment method,but also broadens the application scope of the Bayesian network. 展开更多
关键词 equipment system-of-systems architecture(ESoSA) contribution rate evaluation fuzzy Bayesian network(FBN) fuzzy set theory
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Weapons system portfolio selection based on the contribution rate evaluation of system of systems 被引量:11
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作者 DOU Yajie ZHOU Zhexuan +1 位作者 ZHAO Danling WEI Yong 《Journal of Systems Engineering and Electronics》 SCIE EI CSCD 2019年第5期905-919,共15页
The weapons system portfolio selection problem arises at the equipment demonstration stage and deals with the military application requirements.Further,the contribution rate of the system is one of the important indic... The weapons system portfolio selection problem arises at the equipment demonstration stage and deals with the military application requirements.Further,the contribution rate of the system is one of the important indicators to evaluate the role of a system,which can facilitate the weapons system portfolio selection.Therefore,combining the system contribution rate with system portfolio selection is the focus of this study.It also focuses on calculating the contribution rates of multiple equipment systems with various types of capabilities.The contribution rate is measured by establishing a hierarchical multi-criteria value model from three dimensions.Based on the value model,the feasible portfolios are developed under certain cost constraints and the optimal weapons system portfolios are obtained by using the classification optimization selection strategy.Finally,an illustrative example is presented to verify the feasibility of the proposed model. 展开更多
关键词 WEAPON SYSTEM SYSTEM of systems (SoS) portfolioselection contribution rate EVALUATION DECISION analysis
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Weapons equipment portfolios selection based on equipment system contribution rates 被引量:4
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作者 LIU Peng LI Jichao +2 位作者 XIA Boyuan ZHAO Danling TAN Yuejin 《Journal of Systems Engineering and Electronics》 SCIE EI CSCD 2021年第3期584-595,共12页
Equipment selection is an essential work in the research and development planning of equipment.The scientific and rational development of weapons equipment portfolios is of considerable significance to the optimizatio... Equipment selection is an essential work in the research and development planning of equipment.The scientific and rational development of weapons equipment portfolios is of considerable significance to the optimization of equipment architecture design,the adequate resources allocation,and the joint combat performance.From the system view,this paper proposes a method of weapons equipment portfolios selection(WEPS)based on the contribution rate of weapon systems,providing a new idea for weapon equipment portfolio selection.Firstly,we analyze the WEPS problem and the concept of the contribution rate under the systems background.Secondly,we propose a combat network modeling method for weapon equipment systems based on the function chain.Thirdly,we propose a WEPS method based on the contribution rate,fully considering the correlation relationships between potential weapons and the old weapon systems by the combat network model,under the limitation of capability demands and budget resources,with the objective to maximally increasing the combat ability of weapon systems.Finally,we make a case study with a specific WEPS problem where the whole calculation processes and results are analyzed and exhibited to verify the feasibility and effectiveness of the proposed method model. 展开更多
关键词 weapons equipment system systems contribution rate equipment portfolio selection combat capability combat network
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Online Contribution Rate Based Fault Diagnosis for Nonlinear Industrial Pro cesses 被引量:12
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作者 PENG Kai-Xiang ZHANG Kai LI Gang 《自动化学报》 EI CSCD 北大核心 2014年第3期423-430,共8页
在过去的十年,核主管部件分析(KPCA ) 在监视区域的数据驱动的过程相当流行地出现了。庞大的工作被做了显示出它的简洁,可行性,和有效性。然而,核诡计的介绍使直接为差错诊断采用传统的贡献阴谋不可能。在这份报纸,根据重游并且分... 在过去的十年,核主管部件分析(KPCA ) 在监视区域的数据驱动的过程相当流行地出现了。庞大的工作被做了显示出它的简洁,可行性,和有效性。然而,核诡计的介绍使直接为差错诊断采用传统的贡献阴谋不可能。在这份报纸,根据重游并且分析存在, KPCA 相关的诊断来临,新贡献率基于方法被建议它能清楚地解释有缺点的变量。而且,为联机非线性的诊断的一个计划被建立。最后,连续搅动的坦克反应堆(CSTR ) 上的案例研究基准被使用存取新方法论的有效性,在有传统的线性方法的比较也被包含的地方。 展开更多
关键词 故障诊断 非线性 搅拌釜式反应器 工业 费率 核主成分分析 KPCA 数据驱动
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A Research for Regional Contribution Rate of Internal Source and External Source of PM_(2.5) Based on Set Pair Analysis Method 被引量:1
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作者 Zhou Yejing Zhou Jingxuan Xiao Renbin 《Meteorological and Environmental Research》 CAS 2016年第2期36-40,44,共6页
A problem of the air pollution control in China is getting to know a regional contribution rate of internal and external source of PM2.5. In this paper,Set Pair Analysis( SPA) method is proposed to calculate the con... A problem of the air pollution control in China is getting to know a regional contribution rate of internal and external source of PM2.5. In this paper,Set Pair Analysis( SPA) method is proposed to calculate the contribution rate of PM2.5in Dongguan City. Due to geographic,meteorological factors and the low concentration of air pollutants in Qingxi area,the PM2.5in this place is mainly contributed by the regional transport of air pollutants from other inside areas of Dongguan,and less affected by the outside of Dongguan. So the concentration of PM2.5in Qingxi area can reflect the Dongguan's basic background concentration of PM2.5. On the basis of the basic background concentration,firstly the concentration of each pollutant components is divided into the internal part and the mixed part. Secondly using the source apportionment samples of five monitoring sites in Dongguan we can respectively construct a sample set A and an evaluation set B. Thirdly the SPA is operated onto the mixed part in terms of set B.At last the connection degree between the concentration of each pollutant components and external source and internal source will be calculated,that is the contribution rate. The research reveals that the contribution rate of internal source and external source of PM2.5in Dongguan City is 83%and 17% respectively,which roughly met expectations. This method is simple and effective and it can provide a reference for the government taking reduction measures to control PM2.5pollutants emission. 展开更多
关键词 Set Pair Analysis Connection degree PM2.5 Internal source External source contribution rate
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Contribution Rate of Agricultural Informationization to Growth of Agricultural Economy in Hubei Province and Its Influencing Factors
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作者 Cheng JIA Chunping XIA Yi CAI 《Asian Agricultural Research》 2017年第6期35-39,共5页
Agricultural informationization is the objective demand for transforming the traditional agriculture and promoting the development of agricultural modernization. Using the statistical data of the gross agricultural ou... Agricultural informationization is the objective demand for transforming the traditional agriculture and promoting the development of agricultural modernization. Using the statistical data of the gross agricultural output value of Hubei Province in 2005-2014,based on the C-D production function,it calculated the average contribution rate(2. 48%) of agricultural informationization to the growth of agricultural economy in Hubei Province,indicating that agricultural informationization can promote growth of agricultural economy. This is basically consistent with previous findings. In addition,investment in agricultural informationization and broadband access rate also influenced the growth of agricultural economy in Hubei Province. Therefore,government should further improve the infrastructure of agricultural informationization,strengthen training of farmers’ information skills,establish auxiliary mechanism for achievement feedback of information-based agricultural production,increase the contribution rate of informationization to agricultural operation and management,promote the contribution of informationization to the growth of agricultural economy,so as to increase agricultural income of farmers. 展开更多
关键词 Agricultural informationization Agricultural economy contribution rate Influencing factors Agricultural income
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Quark Loop Contribution to the Gluon Damping Rate in Hot QCD
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作者 马智磊 朱佳庆 +1 位作者 史超逸 李云德 《Chinese Physics Letters》 SCIE CAS CSCD 2015年第12期22-25,共4页
The contribution of the quark loop to the gluon damping rate at zero momentum is calculated using the effective perturbative expansion technique developed by Braaten and Pisarski. It is shown that in the temperature r... The contribution of the quark loop to the gluon damping rate at zero momentum is calculated using the effective perturbative expansion technique developed by Braaten and Pisarski. It is shown that in the temperature range accessible in the present heavy-ion experiments, the contribution of the quark loop can not be ignored. The numerical results show that the quark loop provides ~n apparent contribution to the gluon damping rate at temperatures of experimental interest. 展开更多
关键词 Quark Loop contribution to the Gluon Damping rate in Hot QCD
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Forecast model of safety economy contribution rate of China
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作者 刘莉君 施式亮 《Journal of Coal Science & Engineering(China)》 2005年第2期109-111,共3页
It is the rational and exact computation of the safety economy contribution rate that has the far-reaching realistic meaning to the improvement of society cognition to safety and the investment to the nation safety an... It is the rational and exact computation of the safety economy contribution rate that has the far-reaching realistic meaning to the improvement of society cognition to safety and the investment to the nation safety and the national macro-safety deci-sion-makings. The accurate function between safety inputs and outputs was obtained through a founded econometric model. Then the forecasted safety economy contribution rate is 3.01% and the forecasted ratio between safety inputs and outputs is 1:1.81 in China in 2005. And the model accords with the practice of China and the results are satis-fying. 展开更多
关键词 中国 安全投入 安全产出 安全经济贡献率 预报模型
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Factors contributing to the oxygen concentration over the Qinghai-Tibetan Plateau and its contribution rate calculation
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作者 Peijun SHI Ying ZHANG +6 位作者 Yanqiang CHEN Wenquan ZHU Xiaokang HU Heyi YANG Lu JIANG Yonggui MA Haiping TANG 《Science China Earth Sciences》 SCIE EI CAS CSCD 2024年第2期497-509,共13页
A decline in atmospheric oxygen concentration is projected in the 21st century given the background of global warming.The Qinghai-Tibetan Plateau is located at a high altitude,and thus,it faces a hypoxia challenge;how... A decline in atmospheric oxygen concentration is projected in the 21st century given the background of global warming.The Qinghai-Tibetan Plateau is located at a high altitude,and thus,it faces a hypoxia challenge;however,knowledge of the factors contributing to its atmospheric oxygen concentration is still lacking.Here,we conducted joint observations of ecosystem oxygen production and carbon sinks and near-surface atmospheric oxygen concentrations on the Qinghai-Tibetan Plateau and meteorological elements at Beijing Fangshan Station.Using seasonal differences and statistical methods,we calculated the relative contribution rates of vegetation to changes in atmospheric oxygen concentration.Our results indicate that solar radiation,atmospheric humidity,and ecosystem oxygen consumption and production have a significant impact on the atmospheric oxygen concentration,and the impact shows temporal and spatial differences.Vegetation significantly impacts the oxygen concentration,with a contribution rate of 16.7%–24.5%,which is underestimated in existing research.Our findings provide important insights into the factors that influence atmospheric oxygen concentration and highlight the contribution of vegetation.To better understand the oxygen dynamics of the Qinghai-Tibetan Plateau,we recommend further field observations of soil respiration and vegetation photosynthesis to clarify the contributions of carbon storage,carbon sinks and other factors to the near-surface atmospheric oxygen concentration. 展开更多
关键词 Qinghai-Tibetan Plateau Oxygen concentration Relative contribution rate Air temperature VEGETATION
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Variation Diagnosis and Regional Comparison of Different Intensity of Rainfalls and Their Contribution to Total Rainfall in China in the Context of Global Warming 被引量:2
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作者 Feng KONG 《Asian Agricultural Research》 2019年第8期45-55,共11页
Using the data of 545 meteorological stations in 1961-2015,according to the rainfall intensity classification standard issued by the China Meteorological Administration,the rainfall events were divided into six intens... Using the data of 545 meteorological stations in 1961-2015,according to the rainfall intensity classification standard issued by the China Meteorological Administration,the rainfall events were divided into six intensities: light rain,moderate rain,heavy rain,torrential rain,downpour and heavy downpour. The latter three were recorded as total torrential rain,and all the six were recorded as the total rainfall. In terms of the interannual rainfall and rainy days,the whole China was regarded as an object. Firstly,the annual rainfall and rainy day of different intensity of rainfalls of 545 stations in 1961-2015 were calculated. Then,the variation trend of rainfall and rainy days was calculated. Finally,the variation trend of contribution of different intensity of rainfalls and rainy days to total rainfall and rainy days were diagnosed. It obtained the following results.( i) The light rain in China was declining from 1961 to 2015,and the trend values of light rain and rainy days were-411. 44 mm/yr and-136. 99 d/yr,respectively. Heavy rain and total heavy rainfall showed an increasing trend,with rainfall and rainy day trends of 127. 02 and 463. 94 mm/yr and 7. 93 and 4. 24 d/yr,respectively. The total rainfall showed a ' hockey' phenomenon of ' first rise,then decline',and the trend values of rainfall and rainy days were 204. 29 mm/yr and-95. 81 d/yr,respectively. Except the northern region,the rainfall in most parts of China was dominated by increasing trends and was moving towards extremes.( ii) In terms of rainfall contribution rate,the contribution of light rain to total rainfall showed a declining trend,and the trend values of rainfall and rainy day contribution were both-0. 11%/yr. The contribution of other intensity rainfalls to total rainfall showed an increasing trend. The contribution of torrential rain to the total torrential rain showed a declining trend. The contribution trends of rainfall and rainy days were-0. 06% and-0. 03%/yr,respectively. The contribution of downpour and heavy downpour to total torrential rain showed an increasing trend,indicating the intensity of torrential rain in China is increasing. Although the contribution rate of different intensity of rainfalls to total rainfall was different in different areas of China,the contribution rate of heavy rainfall to total rainfall in most areas showed an increasing trend.( iii) Through comparing the rainfall and rainy days of six different intensity of rainfalls,it can be found that China’s heavy rainfall events are increasing and the rainfall intensity is developing towards extremes. 展开更多
关键词 RAINFALL classification RAINFALL and RAINY DAYS VARIATION trend RAINFALL contribution rate Heavy downpour China
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Contribution of Mass Elevation Effect to the Altitudinal Distribution of Global Treelines 被引量:10
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作者 ZHAO Fang ZHANG Bai-ping +4 位作者 ZHANG Shuo QI Wen-wen HE Wen-hui WANG Jing YAO Yong-hui 《Journal of Mountain Science》 SCIE CSCD 2015年第2期289-297,共9页
Alpine treeline, as a prominent ecological boundary between forested mountain slopes and alpine meadow/shrub, is highly complex in altitudinal distribution and sensitive to warming climate. Great efforts have been mad... Alpine treeline, as a prominent ecological boundary between forested mountain slopes and alpine meadow/shrub, is highly complex in altitudinal distribution and sensitive to warming climate. Great efforts have been made to explore their distribution patterns and ecological mechanisms that determine these patterns for more than 100 years, and quite a number of geographical and ecophysiological models have been developed to correlate treeline altitude with latitude or a latitude related temperature. However,on a global scale, all of these models have great difficulties to accurately predict treeline elevation due to the extreme diversity of treeline site conditions.One of the major reasons is that "mass elevation effect"(MEE) has not been quantified globally and related with global treeline elevations although it has been observed and its effect on treeline elevations in the Eurasian continent and Northern Hemisphere recognized. In this study, we collected and compiled a total of 594 treeline sites all over the world from literatures, and explored how MEE affects globaltreeline elevation by developing a ternary linear regression model with intra-mountain base elevation(IMBE, as a proxy of MEE), latitude and continentality as independent variables. The results indicated that IMBE, latitude and continentality together could explain 92% of global treeline elevation variability, and that IMBE contributes the most(52.2%), latitude the second(40%) and continentality the least(7.8%) to the altitudinal distribution of global treelines. In the Northern Hemisphere, the three factors' contributions amount to 50.4%, 45.9% and 3.7% respectively; in the south hemisphere, their contributions are 38.3%, 53%, and 8.7%, respectively. This indicates that MEE, virtually the heating effect of macro-landforms, is actually the most significant factor for the altitudinal distribution of treelines across the globe, and that latitude is relatively more significant for treeline elevation in the Southern Hemisphere probably due to fewer macro-landforms there. 展开更多
关键词 海拔分布 质量效应 线性回归模型 高山草甸 生态机制 气候变暖 分布格局 生态模型
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Contribution of Agricultural Input to Output in Hohhot City
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作者 Tinghe DENG Jie TIAN 《Asian Agricultural Research》 2013年第6期37-39,42,共4页
Based on the research data from the economics and management platform of Inner Mongolia Agricultural University,we analyze the changes in the input of agricultural production factors,such as farmland,labor and capital... Based on the research data from the economics and management platform of Inner Mongolia Agricultural University,we analyze the changes in the input of agricultural production factors,such as farmland,labor and capital in Hohhot City. Based on the principle of econometrics,we select the agricultural production input-output data in Hohhot City during the period 1992-2010,and establish the econometric model using Cobb-Douglas production factor,to estimate the rate of contribution of agricultural input to the growth of agricultural output value,and study the quantitative relations between agricultural input and agricultural output value. The results show that in Hohhot City,the contribution of chemical fertilizer input to the growth of agricultural output value is the greatest; the contribution of mechanical power to agricultural output value is still not brought into full play; the contribution of remaining production inputs ( including technical progress) accounts for 35. 69% . In the future,Hohhot City should pay more attention to the technical input to develop agriculture. 展开更多
关键词 AGRICULTURE INPUT and OUTPUT contribution rate Hoh
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基于机器学习的茶树DNA聚类算法
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作者 杨小平 倪萍 +4 位作者 诸葛天秋 罗跃新 郭春雨 庞月兰 吴雨婷 《广西大学学报(自然科学版)》 CAS 北大核心 2024年第2期386-399,共14页
为了研究茶树基因序列的聚类问题,设计一种基于累计方差贡献率进行改进的核主成分分析(KPCA)与k均值(k-means)++聚类算法相结合的降维聚类算法(KPCA-k-means++)。将基因库数据集筛选分组后,利用k-mers算法提取基因数据的数据特征,根据... 为了研究茶树基因序列的聚类问题,设计一种基于累计方差贡献率进行改进的核主成分分析(KPCA)与k均值(k-means)++聚类算法相结合的降维聚类算法(KPCA-k-means++)。将基因库数据集筛选分组后,利用k-mers算法提取基因数据的数据特征,根据累计方差贡献率的占比大于85%的标准确定降维主元个数对KPCA进行降维改进并采用k-means++算法对降维后数据聚类,通过CH(Calinski-Harabaze Index)指标和响应时间分析聚类结果。结果表明:在单独聚类、KPCA聚类、改进PCA聚类、改进KPCA聚类4种处理方式中,改进KPCA-k-means++算法在不同处理方式和不同样本数的对比下,CH指标均为最高,与未改进时相比平均高出33%。在响应时间方面,改进KPCA-k-means++算法与同样改进PCA-k-means++算法在不同聚类数和样本数的对比下响应时间均较短。改进KPCA-k-means++算法能够保证对于茶树的基因序列的聚类准确率和聚类速度,表现出极好的聚类稳定性。 展开更多
关键词 核主成分分析 累计方差贡献率 K均值聚类算法 基因聚类
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黄土高原径流侵蚀功率输沙模型的改进
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作者 于坤霞 李天毅 +4 位作者 贾路 李占斌 李鹏 丛佩娟 李斌斌 《农业工程学报》 EI CAS CSCD 北大核心 2024年第10期107-116,共10页
水土流失对流域生态危害严重,输沙量模拟和预测可以为流域水土流失防治提供依据,因此精确的输沙模型是流域水土流失治理的重要工具。为了精确模拟变化环境下黄土高原年输沙量,该研究基于黄土高原19个水文站的径流和输沙数据,通过随机森... 水土流失对流域生态危害严重,输沙量模拟和预测可以为流域水土流失防治提供依据,因此精确的输沙模型是流域水土流失治理的重要工具。为了精确模拟变化环境下黄土高原年输沙量,该研究基于黄土高原19个水文站的径流和输沙数据,通过随机森林变量重要性度量方法评估年径流侵蚀功率、淤地坝指数、淤地坝相对指数、归一化植被指数、不透水地面积等因子对流域年输沙量的影响,使用非线性最小二乘法估算年输沙模型参数,对比分析不同因子组合的年输沙模型精度,提出适用性较强的黄土高原年输沙模型,据此开展年输沙量变化贡献率分析。结果表明:1)以幂函数形式构建的仅含径流侵蚀功率单因子输沙模型精度与流域面积有显著的负相关关系,相关系数为-0.505(P<0.05),模型精度随着流域面积增大而下降,在面积大于7000 km^(2)的流域适用性较差;2)年径流侵蚀功率、淤地坝指数及不透水地面积因子组合建立的多因子年输沙模型在黄土高原适用性最佳,模型在率定期纳什效率系数平均值为0.84,均方根误差平均值为0.21亿t,在验证期纳什系数平均值为0.79,均方根误差平均值为0.27亿t。3)影响研究流域年输沙量变化的因素依次是:年径流侵蚀功率、不透水地面积和淤地坝指数。研究可以为黄土高原不同区域水土流失防治和生态治理工作提供理论支撑。 展开更多
关键词 侵蚀 径流 年输沙量 径流侵蚀功率 淤地坝指数 不透水地面积 贡献率
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基于C-D生产函数的灌区节水贡献率研究
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作者 徐凯 沈建强 +5 位作者 刘敏昊 杨开静 白明皓 雷波 徐立荣 翟林鹏 《中国农村水利水电》 北大核心 2024年第7期234-240,254,共8页
为挖掘灌区节水目标实现路径,提高灌区用水效率,研究分析了大中型灌区水利工程建设管护对节水战略目标的贡献程度。以江苏省为例,选取6个典型灌区,收集了2015-2022年统计数据,分别计算渠系工程、田间工程和非工程措施的节水潜力,并据此... 为挖掘灌区节水目标实现路径,提高灌区用水效率,研究分析了大中型灌区水利工程建设管护对节水战略目标的贡献程度。以江苏省为例,选取6个典型灌区,收集了2015-2022年统计数据,分别计算渠系工程、田间工程和非工程措施的节水潜力,并据此计算灌区总节水潜力。以水利工程投入、劳动力投入、土地投入、技术进步作为自变量,灌区总节水潜力作为因变量,利用改进C-D生产函数来构建“双对数模型”。利用SPSS软件对数据进行多元线性回归,运用步进法剔除无关变量后建立最优方程,通过弹性系数测算不同变量对节水目标的贡献率大小。结果表明,在灌区总节水潜力组成中,渠系工程节水占比最大,田间工程节水占比最小;水利工程投入、土地投入、技术进步对节水目标的平均贡献率分别为45.5%、30.4%、5.2%,但技术进步贡献率呈现逐年增长的趋势,水利工程收入贡献率先减小后增大。大型灌区水利工程对灌区节水的贡献率高于中型灌区。该研究将C-D生产函数模型运用到节水评价当中,结果较为合理可靠,可为大中型灌区节水发展提供技术参考。 展开更多
关键词 灌区 节水潜力 柯布-道格拉斯生产函数 贡献率
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漓江上游水沙对降水、土地利用变化的响应
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作者 方荣杰 黄卉 +3 位作者 张帅普 代俊峰 蒋立新 许景璇 《桂林理工大学学报》 CAS 北大核心 2024年第1期115-122,共8页
为了探究漓江流域上游水沙对气候和土地利用变化的响应特征,基于气温、降水量、径流量、输沙量,结合土地利用数据和归一化植被指数(NDVI)数据,应用Mann-Kendall检验法、双累积曲线法分析漓江上游水文气象要素变化趋势,利用累积量斜率变... 为了探究漓江流域上游水沙对气候和土地利用变化的响应特征,基于气温、降水量、径流量、输沙量,结合土地利用数据和归一化植被指数(NDVI)数据,应用Mann-Kendall检验法、双累积曲线法分析漓江上游水文气象要素变化趋势,利用累积量斜率变化率比较法定量揭示气候因子对上游径流变化的贡献率,结合植被覆盖变化特征探讨土地利用类型变化对河流水沙的影响。结果表明:1965—2019年漓江流域上游气温呈显著增加趋势,降水量、径流量、输沙量未呈现显著增加或减少趋势,同时期NDVI呈上升趋势,但土地利用结构未发生明显变化,仍以林地、耕地为主。漓江上游气温未出现突变点,降水量与径流量于1991年发生突变,1992—2019年漓江上游NDVI平均值显著高于突变前的1981—1991年,耕地面积平均值与林地面积平均值显著低于突变前的1981—1991年;输沙量于2003年发生突变,2004—2019年漓江上游NDVI平均值与建设用地面积平均值显著高于1981—2003年。降水对径流改变的贡献率为56.30%,降水量-径流量关系并未在突变点前后发生改变。降水量对输沙量改变的贡献率为-12.67%,降水量-输沙量关系在突变后发生改变。 展开更多
关键词 水沙特征 气候变化 土地利用 贡献率 漓江
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基于机-电-磁-流整体耦合的油阻尼断路器保护特性的容差设计
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作者 乔延华 苏秀苹 李建娜 《现代电子技术》 北大核心 2024年第12期122-128,共7页
油阻尼断路器的主要特点是在电路发生短路、过载等情况时能够自动脱扣,断开电路,从而保护人员和设备的安全,常用于变电站等场所。文章在以往对油阻尼断路器油阻尼力、电磁铁静态特性、操作机构性能等研究的基础上,构建一个基于机-电-磁... 油阻尼断路器的主要特点是在电路发生短路、过载等情况时能够自动脱扣,断开电路,从而保护人员和设备的安全,常用于变电站等场所。文章在以往对油阻尼断路器油阻尼力、电磁铁静态特性、操作机构性能等研究的基础上,构建一个基于机-电-磁-流多体多自由度多场耦合的一体化虚拟样机整体耦合模型;接着对该整体耦合模型的保护特性进行了仿真与分析,通过仿真得到了不同电流倍数下动触头的分断特性,并通过实验验证了整体耦合模型和仿真结果的正确性;最后,为减小产品保护特性的分散程度,提高油阻尼断路器的稳定性,文中结合稳健容差设计技术,选取不同电流倍数下触头的断开时间作为目标函数,以极靴半径、细铁芯半径、粗铁芯半径、粗铁芯高度作为关键设计参数,通过正交试验和贡献率分析法对目标函数进行容差分配,使得触头断开时间的分散度比原来减少39.165%。研究成果将会对电器产品的研发提供理论指导。 展开更多
关键词 油阻尼断路器 保护特性 容差设计 多场耦合 正交试验 贡献率
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养老保险省级统筹对养老保险基金平衡的影响研究
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作者 苏春红 耿嫚嫚 李真 《南方经济》 北大核心 2024年第1期22-38,共17页
提高基本养老保险统筹层次是增强养老金支付能力的重要改革举措,也是实现养老金制度安全规范发展的关键。文章基于养老保险省级统筹改革的准自然实验,利用2008-2019年中国A股上市公司数据,构建双重差分模型实证评估了养老保险统筹改革... 提高基本养老保险统筹层次是增强养老金支付能力的重要改革举措,也是实现养老金制度安全规范发展的关键。文章基于养老保险省级统筹改革的准自然实验,利用2008-2019年中国A股上市公司数据,构建双重差分模型实证评估了养老保险统筹改革对企业实际缴费率及基本养老保险基金平衡的影响。研究发现:省级统筹显著降低了企业养老保险实际缴费率,该结果在更改变量度量方式、排除竞争性解释、考虑异质性处理效应等一系列稳健性检验中仍然成立。养老保险省级统筹在不同征管模式、企业类型及地区层面对企业养老保险实际缴费率存在异质性影响,对于社保征收和税务代征模式、劳动密集度高的企业、所在地区老龄化程度低和财政压力小的企业影响更明显。机制分析发现,市县政府由于“相对剥夺效应”和“逐底竞争效应”所产生的征管强度不足是造成省级统筹改革后企业缴费率下降的重要因素。进一步分析表明,省级统筹改革降低了基金收支平衡,并对中西部省份影响更明显。研究对于加强地方政府征管治理、促进养老保险基金平衡发展具有重要启示,为征管主体间利益关系的平衡及养老保险全国统筹的顺利推进提供了经验证据。 展开更多
关键词 养老保险统筹 征管强度 实际缴费率 基金平衡
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CMIP6耦合模式对青藏高原积雪的未来预估
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作者 陈涛 高歌 +1 位作者 杜晓辉 陈华 《地理科学》 CSCD 北大核心 2024年第5期901-910,共10页
基于第六次国际耦合模式比较计划(CMIP6)的历史模拟试验以及情景预估试验数据,分析了21世纪中(2035—2064年)、后期(2070—2099年)青藏高原积雪相对于参考期(1985—2014年)的变化。结果表明:相对于参考期,21世纪中、后期青藏高原平均年... 基于第六次国际耦合模式比较计划(CMIP6)的历史模拟试验以及情景预估试验数据,分析了21世纪中(2035—2064年)、后期(2070—2099年)青藏高原积雪相对于参考期(1985—2014年)的变化。结果表明:相对于参考期,21世纪中、后期青藏高原平均年积雪日数、平均积雪期均表现为减少,减少幅度总体随着人为辐射强迫的增加而加大;除低强迫情景外,21世纪后期的减少幅度均大于21世纪中期;空间上总体表现为青藏高原东南部的减少幅度大于西北部。21世纪中、后期青藏高原积雪初日均表现为推迟、积雪终日均表现为提前,积雪初日推迟天数是积雪终日提前天数的1.5~2.0倍;人为辐射强迫越高,积雪初(终)日推迟(提前)天数越多;相同情景下21世纪后期积雪初(终)日推迟(提前)天数均多于21世纪中期。降雪(气温)与年积雪日数呈正(负)相关;随着人为辐射强迫的增加,降雪对年积雪日数的相对贡献率总体呈增加趋势;空间特征表现为降雪(气温)对青藏高原南部和北部(东部和西部)的年积雪日数的相对贡献更大。7—12月降雪的减少幅度大于1—6月,这可能是积雪初日推迟天数多于积雪终日提前天数的重要原因。不同情景下青藏高原未来积雪变化差异明显,由此可见,控制温室气体排放对减缓未来青藏高原积雪的减少速率至关重要。 展开更多
关键词 青藏高原 CMIP6 积雪日数 积雪期 气温降雪贡献率
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陕西省环境气象条件评估指数时空变化特征研究
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作者 苏静 孙娴 +2 位作者 胡琳 林杨 王琦 《沙漠与绿洲气象》 2024年第2期146-154,共9页
基于陕西省10地市2015—2020年PM_(2.5)浓度实况监测数据和气象条件评估指数EMI,统计分析EMI和PM_(2.5)相关性及近年EMI的时空分布特征,定量评估气象条件变化及综合治理措施对陕西环境空气质量的影响。结果表明:陕西省2015—2020年EMI... 基于陕西省10地市2015—2020年PM_(2.5)浓度实况监测数据和气象条件评估指数EMI,统计分析EMI和PM_(2.5)相关性及近年EMI的时空分布特征,定量评估气象条件变化及综合治理措施对陕西环境空气质量的影响。结果表明:陕西省2015—2020年EMI可较好地表征和评估气象条件变化导致的PM_(2.5)浓度变化。2015—2020年EMI呈线性降低趋势,气象条件持续向好。月EMI均呈明显的单谷分布特征,EMI冬半年大,夏半年小。各区域EMI总体上呈关中高、陕南次之、陕北最低的分布特点,关中中部、东部EMI最大。EMI正距平百分比高值区主要分布在关中地区,各年关中均有60%以上面积正距平,其中2016年冬季关中83.0%面积正距平,37.5%面积正距平超过100%。2020年陕西省各区域环境空气质量较2015—2019年均有明显改善,全省PM_(2.5)浓度较前5 a平均降低24.8%,全省气象条件改善使PM2.5浓度较近5 a降低16.4%,排放变化使得PM_(2.5)浓度较前5 a平均下降9.4%,可见,近年陕西省大气污染综合治理措施成果显著,环境质量明显改善。 展开更多
关键词 陕西省 细颗粒物PM_(2.5) 环境空气质量评价 气象条件评估指数(EMI) 贡献率
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