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中国经济增长的可能性:一种基于修正的索洛模型的估算 被引量:9
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作者 郭磊 《当代经济科学》 CSSCI 北大核心 2005年第3期49-52,110,共5页
索洛模型这一经典的经济增长模型有它无可比拟的优点,但对于考察中国问题来说,也有一些内在缺陷。本文根据中国经济增长的特征事实,对索洛模型做出了一些修正,并据此对中国经济增长的可能性进行了重新估算。
关键词 索洛模型 结构效应 变量估算
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Stäckel引力势理论的拓展及其应用
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作者 顾建宇 董小波 《天文学进展》 CSCD 北大核心 2021年第2期144-186,共43页
Stäckel引力势是一类最普遍形式的可分离势。具有Stäckel形式的星系是完全可积系统,即其中的恒星轨道都是规则的,其运动积分可以解析求出。运动积分——特别是作用量(J,一种特殊的运动积分),能简化恒星运动的描述;研究星系中... Stäckel引力势是一类最普遍形式的可分离势。具有Stäckel形式的星系是完全可积系统,即其中的恒星轨道都是规则的,其运动积分可以解析求出。运动积分——特别是作用量(J,一种特殊的运动积分),能简化恒星运动的描述;研究星系中恒星的运动学和动力学的重要途径是作用量空间,比如使用以作用量作为参量的分布函数f(J_(R),L_(z),J_(z))。通过将一般星系的引力势局部地近似成Stäckel势,人们可以估算一般星系中恒星运动的作用量。介绍天文学家在拓展Stäckel引力势的研究上取得的重大进展:在基于Stäckel势理论估算一般星系中的作用量(或运动积分)方面,开发出了若干快速数值算法(例如Stäckel作弊法[Stäckel Fudge]、Stäckel拟合法),基于环面映射的收敛性高精度数值算法(例如轨道积分拟合生成函数法、迭代环面构造法),以及提出作为近似的运动积的解析表达式;在分布函数的构造方面,基于上述估算的作用量或直接利用Stäckel势的运动积分公式(主要是I_(3)表达式),提出了一些分布函数模型,f(J_(R),L_(z),J_(z))或f(E,L_(z),I_(3))。这些进展使得人们可以对星系开展基于分布函数的建模。此外,还介绍近几年把这些方法应用到银河系观测数据的若干代表性工作。 展开更多
关键词 Stäckel引力势 作用量-角变量估算 银河系分布函数建模
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Application of Log Kriging on Estimated Reserves of the 10-9 Ore Body of Lutangba in the Gejiu Tin Deposits 被引量:2
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作者 DENG Ming-guo LI Wen-chang +5 位作者 LI Bo LI Li-hui JIANG Shun-de XIONG Guang-xu ZHANG Xue-shu YU Hai-jun 《Journal of China University of Mining and Technology》 EI 2007年第2期286-289,共4页
The approaches adopted so far in China to calculate reserves of ore deposits have largely been dependent on polygonal methods, including a cross-section method and a geological block method. However, for various reaso... The approaches adopted so far in China to calculate reserves of ore deposits have largely been dependent on polygonal methods, including a cross-section method and a geological block method. However, for various reasons, especially, the complexity of the geology, and the ore bodies, the deposits became gradually known as development and exploitation took place. There is a certain difference between the prospecting and mining, which will have a great impact on both geological and cutoff grade at the stage of geological mine construction and production. As much accurate information as possible on the spatial distribution patterns of ore bodies and global reserves is essential to improve the production efficiency and reduce production cost. The 10-9 ore body of Lutangba in the Gejiu Tin Deposits was selected as our research object, using a log Kriging and an inverse distance weighing method. In our paper the results are compared with the reserves calculated by the polygonal block method. The global estimate and estimation errors associated with each estimation method are discussed. 展开更多
关键词 log Kriging composite samples semi-variogram inverse distance weighing method reserves estimation Geiiu
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Cave Environmental Changes: The Possibilities of Assessment
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作者 Elena Trofimova 《Journal of Environmental Science and Engineering(B)》 2013年第11期640-642,共3页
The aim of this research is to apply a new approach to assess cave environmental changes--CDI (cave disturbance index), based on the five main categories: geomorphology, hydrology, atmosphere, biology and culture. ... The aim of this research is to apply a new approach to assess cave environmental changes--CDI (cave disturbance index), based on the five main categories: geomorphology, hydrology, atmosphere, biology and culture. The indicators of every category are considered in detail. The quantitative estimation of total CDI is proposed. 展开更多
关键词 Cave environmental changes ASSESSMENT CDI.
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Quantitative Estimation on Contributions of Climate Changes and Human Activities to Decreasing Runoff in Weihe River Basin, China 被引量:6
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作者 HUANG Shengzhi HUANG Qiang CHEN Yutong 《Chinese Geographical Science》 SCIE CSCD 2015年第5期569-581,共13页
Human activities and climate changes are deemed to be two primary driving factors influencing the changes of hydrological processes, and quantitatively separating their influences on runoff changes will be of great si... Human activities and climate changes are deemed to be two primary driving factors influencing the changes of hydrological processes, and quantitatively separating their influences on runoff changes will be of great significance to regional water resources planning and management. In this study, the impact of climate changes and human activities was initially qualitatively distinguished through a coupled water and energy budgets analysis, and then this effect was further separated by means of a quantitative estimation based on hydrological sensitivity analysis. The results show that: 1) precipitation, wind speed, potential evapotranspiration and runoff have a significantly decreasing trend, while temperature has a remarkably increasing tendency in the Weihe River Basin, China; 2) the major driving factor on runoff decrease in the 1970 s and 1990 s in the basin is climate changes compared with that in the baseline 1960 s, while that in the 1980 s and 2000 s is human activities. Compared with the results based on Variable Infiltration Capacity(VIC) model, the contributions calculated in this study have certain reliability. The results are of great significance to local water resources planning and management. 展开更多
关键词 climate changes human activities runoff decrease quantitative analysis Weihe River Basin
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试论回归分析在预测或估算中的应用
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作者 荆小波 《科技园地》 1995年第3期12-14,共3页
关键词 回归分析 变量估算 变量预测 数理统计方法
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全球价值链的深度嵌入与技术进步关系的机理与测算 被引量:16
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作者 宋宪萍 贾芸菲 《经济纵横》 CSSCI 北大核心 2019年第12期74-85,共12页
在深度嵌入全球价值链过程中,需要重新思考国际分工格局,对全球价值链的技术进步效果进行重新审视。研究发现,初步嵌入全球价值链的发展中国家努力与跨国公司的要求相匹配,在此条件下实现的技术进步只是一种"幻像"。一旦代工... 在深度嵌入全球价值链过程中,需要重新思考国际分工格局,对全球价值链的技术进步效果进行重新审视。研究发现,初步嵌入全球价值链的发展中国家努力与跨国公司的要求相匹配,在此条件下实现的技术进步只是一种"幻像"。一旦代工企业有可能更进一步攀升到价值链高端时,就会触及发达国家跨国公司的利益,形成"技术进步悖论"。在非对称的贸易模式下,全球价值链实质上仍然是一个有中心和外围、主导和依附关系的国际劳动分工体系,技术创新的"锁定效应"和分工固化风险更加突出。运用投入产出分析法,利用2007-2016年我国23个工业行业面板数据进行实证分析后发现,多个行业的全球价值链嵌入程度与技术进步呈倒U型关系。因此,需要彻底转变经济增长模式,构建国家创新链。 展开更多
关键词 全球价值链 技术进步 隐性变量估算 投入产出表
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