Firstly, the research progress of grey model GM （1,1） is summarized, which is divided into three development stages： assimilation, alienation and melting stages. Then, the matrix analysis theory is used to study th...Firstly, the research progress of grey model GM （1,1） is summarized, which is divided into three development stages： assimilation, alienation and melting stages. Then, the matrix analysis theory is used to study the modeling mechanism of GM （1,1）, which decomposes the modeling data matrix into raw data transformation matrix, accumulated generating operation matrix and background value selection matrix. The changes of these three matrices are the essential reasons affecting the modeling and the accuracy of GM （1,1）. Finally, the paper proposes a generalization grey model GGM （1,1）, which is a extended form of GM （1,1） and also a unified form of model GM （1,1）, model GM （1,1,α）, stage grey model, hopping grey model, generalized accumulated model, strengthening operator model, weakening operator model and unequal interval model. And the theory and practical significance of the extended model is analyzed.展开更多
Based on mineral component and in-situ vane shear strength of deep-sea sediment, four kinds of simulative soils were prepared by mixing different bentonites with water in order to find the best simulative soil for the...Based on mineral component and in-situ vane shear strength of deep-sea sediment, four kinds of simulative soils were prepared by mixing different bentonites with water in order to find the best simulative soil for the deep-sea sediment collected from the Pacific C-C area. Shear creep characteristics of the simulative soil were studied by shear creep test and shear creep parameters were determined by Burgers creep model. Research results show that the shear creep curves of the simulative soil can be divided into transient creep, unstable creep and stable creep, where the unstable creep stage is very short due to its high water content. The shear creep parameters increase with compressive stress and change slightly or fluctuate to approach a constant value with shear stress, and thus average creep parameters under the same compressive stress are used as the creep parameters of the simulative soil. Traction of the deep-sea mining machine walking at a constant velocity can be calculated by the shear creep constitutive equation of the deep-sea simulative soil, which provides a theoretical basis for safe operation and optimal design of the deep-sea mining machine.展开更多
This paper focuses on synthesizing a mixed robust H_2/H_∞ linear parameter varying（LPV） controller for the longitudinal motion of an air-breathing hypersonic vehicle via a high order singular value decomposition（H...This paper focuses on synthesizing a mixed robust H_2/H_∞ linear parameter varying（LPV） controller for the longitudinal motion of an air-breathing hypersonic vehicle via a high order singular value decomposition（HOSVD） approach.The design of hypersonic flight control systems is highly challenging due to the enormous complexity of the vehicle dynamics and the presence of significant uncertainties.Motivated by recent results on both LPV control and tensor-product（TP） model transformation approach,the velocity and altitude tracking control problems for the air-breathing hypersonic vehicle is reduced to that of a state feedback stabilizing controller design for a polytopic LPV system with guaranteed performances.The controller implementation is converted into a convex optimization problem with parameterdependent linear matrix inequalities（LMIs） constraints,which is intuitively tractable using LMI control toolbox.Finally,numerical simulation results demonstrate the effectiveness of the proposed approach.展开更多
基于中国科学院自主研发的第二代地球系统模式CAS-ESM2.0,本研究通过在陆面分量模式CoLM(Common Land Model)中引入植被水力模型以替换原有的经验性方案,开展了两组34年(1981~2014年)的AMIP(Atmospheric Model Intercomparison Project...基于中国科学院自主研发的第二代地球系统模式CAS-ESM2.0,本研究通过在陆面分量模式CoLM(Common Land Model)中引入植被水力模型以替换原有的经验性方案,开展了两组34年(1981~2014年)的AMIP(Atmospheric Model Intercomparison Project)数值模拟试验,探讨了植被水力方案的引入对中国夏季降水模拟的影响。结果表明,植被水力方案的引入能够显著降低CAS-ESM2.0模式对中国夏季降水气候态的模拟偏差,特别是显著改进了中国东部、青藏高原降水的低估,青藏高原以东的川西地区降水高估的偏差,同时也改善了夏季降水年际变率和极端大雨日数的模拟性能。进一步分析显示,植被水力方案的改进显著减小了土壤湿度在长江流域偏干、青藏高原偏湿的模式模拟偏差,降低了我国中东部以及青藏高原地表感热通量和潜热通量的模拟偏差,改善了模式对陆气相互作用过程的模拟能力。陆气相互作用的改进显著提升了模式对东亚季风环流的模拟,改进后的模式模拟的西北太平洋海平面气压的负偏差显著降低,有利于西南季风以及西北太平洋向我国东部的水汽输送,同时在对流层低层出现反气旋异常响应,有效改善了中国东部南风偏弱及水汽辐合偏弱的模拟偏差,使得我国东部降水负偏差显著减小。以上结果表明,包括植被水力过程的陆气相互作用的合理表述是改善东亚夏季降水模拟的重要途径之一。展开更多
以往开展的基于长江流域WRF(Weather Research and Forecasting)模式的微物理过程方案参数化优选的研究,没有对长江中下游这一特定区域多个气象要素积云对流参数化方案进行优选。本研究在适合微物理过程、边界层等参数化方案的基础上,...以往开展的基于长江流域WRF(Weather Research and Forecasting)模式的微物理过程方案参数化优选的研究,没有对长江中下游这一特定区域多个气象要素积云对流参数化方案进行优选。本研究在适合微物理过程、边界层等参数化方案的基础上,选用长江中下游流域为研究对象,针对降水、气温进行三种积云对流参数化方案KF(Kain-Fritsch)、BMJ(Betts-Miller-Janjic)及GF(Grell-Freitas)的优选,并同时从不同海拔、水汽来源两个角度对比分析三种方案产生差异的原因,从而针对不同天气型选择合适的参数化方案。结果表明:(1)选取的三种积云对流参数化方案在降水和气温模拟结果表现不同。KF方案在降水模拟中表现较好,日降水模拟相关系数为0.73~0.77;GF方案在气温模拟中表现优异,日均气温模拟相关系数为0.71~0.77。(2)三种方案在不同海拔高程的表现差异明显,KF和BMJ方案较好地展现了武陵山—大巴山一带降水与地形的对应关系。在经度剖面上,KF方案2015、2017年6月的降水模拟误差分别为5.96%、6.06%。GF方案则对地形抬升作用的描述过于强烈,导致剖面降雨量变化幅度较大。(3)三种方案模拟结果的水汽来源有所不同,KF方案显示印度洋季风带来充沛水汽,水成物含量少,云水混合比集中,更适合长江中下游流域的降水模拟;GF方案则显示南海暖湿气流较强,水成物含量多,云系发展旺盛,更适合强对流天气频发地区的降水模拟。(4)不同水汽来源对三种积云对流参数化方案模拟结果的精度影响不大。尽管2017年6月较2015年6月受到来自西太平洋的水汽影响更大,但降水模拟结果仍显示KF方案表现最佳。展开更多
在全球变暖背景下,对东亚气候进行准确模拟以研究气候变化至关重要.参数化方案的选择对模式性能有重要影响.利用全球再分析资料驱动WRF(Weather Research and Forecasting)模式对2020年夏季CORDEX(Coordinated Regional Downscaling Exp...在全球变暖背景下,对东亚气候进行准确模拟以研究气候变化至关重要.参数化方案的选择对模式性能有重要影响.利用全球再分析资料驱动WRF(Weather Research and Forecasting)模式对2020年夏季CORDEX(Coordinated Regional Downscaling Experiment)东亚区域进行了分辨率为12.5 km的高分辨率多参数化组合模拟试验,通过设置不同的积云对流(CU)、微物理(MP)和边界层(PBL)方案的组合来研究参数化方案对东亚夏季区域气候模拟的影响.结果表明,2020年夏季降水模拟对积云对流方案最为敏感,其次是微物理方案,边界层方案的影响最小.通过与观测降水的比较,控制(CTL)试验的Modifed Tiedtke,Thompson和MYNN 2.5方案组合在所有试验中表现出最好的再现降水能力,或许可用于东亚夏季强降水的模拟.CU试验降水差异与低层环流偏差有关,积云方案KSAS,Grell-Freitas和BMJ明显的环流偏差是造成降水偏差的主要原因.不同MP试验的模拟降水受不同水成物粒子的垂直分布影响,液态粒子和雪粒子对降水有重要贡献.PBL试验通过边界层高度和地表潜热通量影响降水,发现通常更低的边界层高度和更多的潜热通量能模拟更多的降水.展开更多
基金supported by the National Natural Science Foundation of China(70971103)the Specialized Research Fund for the Doctora Program of Higher Education(20120143110001)
文摘Firstly, the research progress of grey model GM （1,1） is summarized, which is divided into three development stages： assimilation, alienation and melting stages. Then, the matrix analysis theory is used to study the modeling mechanism of GM （1,1）, which decomposes the modeling data matrix into raw data transformation matrix, accumulated generating operation matrix and background value selection matrix. The changes of these three matrices are the essential reasons affecting the modeling and the accuracy of GM （1,1）. Finally, the paper proposes a generalization grey model GGM （1,1）, which is a extended form of GM （1,1） and also a unified form of model GM （1,1）, model GM （1,1,α）, stage grey model, hopping grey model, generalized accumulated model, strengthening operator model, weakening operator model and unequal interval model. And the theory and practical significance of the extended model is analyzed.
基金Project(51274251)supported by the National Natural Science Foundation of China
文摘Based on mineral component and in-situ vane shear strength of deep-sea sediment, four kinds of simulative soils were prepared by mixing different bentonites with water in order to find the best simulative soil for the deep-sea sediment collected from the Pacific C-C area. Shear creep characteristics of the simulative soil were studied by shear creep test and shear creep parameters were determined by Burgers creep model. Research results show that the shear creep curves of the simulative soil can be divided into transient creep, unstable creep and stable creep, where the unstable creep stage is very short due to its high water content. The shear creep parameters increase with compressive stress and change slightly or fluctuate to approach a constant value with shear stress, and thus average creep parameters under the same compressive stress are used as the creep parameters of the simulative soil. Traction of the deep-sea mining machine walking at a constant velocity can be calculated by the shear creep constitutive equation of the deep-sea simulative soil, which provides a theoretical basis for safe operation and optimal design of the deep-sea mining machine.
基金supported by the National Natural Science Foundation of China(6120300761304239+1 种基金61503392)the Natural Science Foundation of Shaanxi Province(2015JQ6213)
文摘This paper focuses on synthesizing a mixed robust H_2/H_∞ linear parameter varying（LPV） controller for the longitudinal motion of an air-breathing hypersonic vehicle via a high order singular value decomposition（HOSVD） approach.The design of hypersonic flight control systems is highly challenging due to the enormous complexity of the vehicle dynamics and the presence of significant uncertainties.Motivated by recent results on both LPV control and tensor-product（TP） model transformation approach,the velocity and altitude tracking control problems for the air-breathing hypersonic vehicle is reduced to that of a state feedback stabilizing controller design for a polytopic LPV system with guaranteed performances.The controller implementation is converted into a convex optimization problem with parameterdependent linear matrix inequalities（LMIs） constraints,which is intuitively tractable using LMI control toolbox.Finally,numerical simulation results demonstrate the effectiveness of the proposed approach.
文摘基于中国科学院自主研发的第二代地球系统模式CAS-ESM2.0,本研究通过在陆面分量模式CoLM(Common Land Model)中引入植被水力模型以替换原有的经验性方案,开展了两组34年(1981~2014年)的AMIP(Atmospheric Model Intercomparison Project)数值模拟试验,探讨了植被水力方案的引入对中国夏季降水模拟的影响。结果表明,植被水力方案的引入能够显著降低CAS-ESM2.0模式对中国夏季降水气候态的模拟偏差,特别是显著改进了中国东部、青藏高原降水的低估,青藏高原以东的川西地区降水高估的偏差,同时也改善了夏季降水年际变率和极端大雨日数的模拟性能。进一步分析显示,植被水力方案的改进显著减小了土壤湿度在长江流域偏干、青藏高原偏湿的模式模拟偏差,降低了我国中东部以及青藏高原地表感热通量和潜热通量的模拟偏差,改善了模式对陆气相互作用过程的模拟能力。陆气相互作用的改进显著提升了模式对东亚季风环流的模拟,改进后的模式模拟的西北太平洋海平面气压的负偏差显著降低,有利于西南季风以及西北太平洋向我国东部的水汽输送,同时在对流层低层出现反气旋异常响应,有效改善了中国东部南风偏弱及水汽辐合偏弱的模拟偏差,使得我国东部降水负偏差显著减小。以上结果表明,包括植被水力过程的陆气相互作用的合理表述是改善东亚夏季降水模拟的重要途径之一。
文摘以往开展的基于长江流域WRF(Weather Research and Forecasting)模式的微物理过程方案参数化优选的研究,没有对长江中下游这一特定区域多个气象要素积云对流参数化方案进行优选。本研究在适合微物理过程、边界层等参数化方案的基础上,选用长江中下游流域为研究对象,针对降水、气温进行三种积云对流参数化方案KF(Kain-Fritsch)、BMJ(Betts-Miller-Janjic)及GF(Grell-Freitas)的优选,并同时从不同海拔、水汽来源两个角度对比分析三种方案产生差异的原因,从而针对不同天气型选择合适的参数化方案。结果表明:(1)选取的三种积云对流参数化方案在降水和气温模拟结果表现不同。KF方案在降水模拟中表现较好,日降水模拟相关系数为0.73~0.77;GF方案在气温模拟中表现优异,日均气温模拟相关系数为0.71~0.77。(2)三种方案在不同海拔高程的表现差异明显,KF和BMJ方案较好地展现了武陵山—大巴山一带降水与地形的对应关系。在经度剖面上,KF方案2015、2017年6月的降水模拟误差分别为5.96%、6.06%。GF方案则对地形抬升作用的描述过于强烈,导致剖面降雨量变化幅度较大。(3)三种方案模拟结果的水汽来源有所不同,KF方案显示印度洋季风带来充沛水汽,水成物含量少,云水混合比集中,更适合长江中下游流域的降水模拟;GF方案则显示南海暖湿气流较强,水成物含量多,云系发展旺盛,更适合强对流天气频发地区的降水模拟。(4)不同水汽来源对三种积云对流参数化方案模拟结果的精度影响不大。尽管2017年6月较2015年6月受到来自西太平洋的水汽影响更大,但降水模拟结果仍显示KF方案表现最佳。
文摘在全球变暖背景下,对东亚气候进行准确模拟以研究气候变化至关重要.参数化方案的选择对模式性能有重要影响.利用全球再分析资料驱动WRF(Weather Research and Forecasting)模式对2020年夏季CORDEX(Coordinated Regional Downscaling Experiment)东亚区域进行了分辨率为12.5 km的高分辨率多参数化组合模拟试验,通过设置不同的积云对流(CU)、微物理(MP)和边界层(PBL)方案的组合来研究参数化方案对东亚夏季区域气候模拟的影响.结果表明,2020年夏季降水模拟对积云对流方案最为敏感,其次是微物理方案,边界层方案的影响最小.通过与观测降水的比较,控制(CTL)试验的Modifed Tiedtke,Thompson和MYNN 2.5方案组合在所有试验中表现出最好的再现降水能力,或许可用于东亚夏季强降水的模拟.CU试验降水差异与低层环流偏差有关,积云方案KSAS,Grell-Freitas和BMJ明显的环流偏差是造成降水偏差的主要原因.不同MP试验的模拟降水受不同水成物粒子的垂直分布影响,液态粒子和雪粒子对降水有重要贡献.PBL试验通过边界层高度和地表潜热通量影响降水,发现通常更低的边界层高度和更多的潜热通量能模拟更多的降水.
