基于随机有限元可靠度的RC结构抗火设计参数优化方法

本文较详细地分析了各设计参数对RC结构抗火能力的影响。在已知结构抗火功能函数的基础上利用随机有限元可靠度的计算方法分析各参数对结构抗火能力的敏感性,根据各参数敏感性的不同,在设计时有意识地对该参数作一些较小的变动,结构的可靠度会明显的增加从而提高了结构的抗火能力。为RC结构抗火设计提供了一种参数优化的方法。     

中国经济行业产出对气象条件变化的敏感性影响分析

为研究天气气候变化对中国经济行业产出的影响变化,引入气象因素的Cobb-Douglas生产函数,采用了带一阶自回归变量的Panel data-Random effect-AR(1)模型,研究经济产出对气象条件变化的边际影响和敏感性分析。研究表明,气象条件变化对中国8个行业、31个省(区、直辖市)的国民经济产出存在显著敏感性影响。在控制资本和劳动力影响因素的条件下,1984—2006年共22年间中国GDP总值对气象条件变化的敏感性影响约为12.36%。在计量经济效益预测中,度量了我国省域行业经济产出对气象条件敏感性影响,总体特征为:北部大于南部,西部大于东部,在北部以中部气象条件相对更为敏感,而在南部以中部气象条件相对更为不敏感,这与自然气候带分布、地理环境、经济发展类型及其水平和气象灾害分布等均有关系。农业、建筑业、批发零售业、工业、交通运输业、服务业、金融业和房地产业对气象条件变化的敏感性影响从大到小依次为25.4%、14.7%、13.2%,10.9%、10.7%、10.7%、9.2%和7.9%。     

Screening bamboo species for salt tolerance using growth parameters,physiological response and osmolytes accumulation as effective indicators

Bamboos are potential species for reclamation of saline soils and water. In this study, the performances of three bamboo species, namely Dendrocalamus strictus (S1), Dendrocalamus longispathus (S2) and Bambusa bambos (S3), were investigated for salinity stress tolerance. After 14 days of treatment with 100?mM NaCl, reduction in shoot length was 66%, 100%, 77%, root length was 77%, 100%, 57%, number of leaves was 50%, 100%, 73% and fresh weight was 30%, 72%, 14% in S1, S2 and S3 species, respectively. Relative water content (RWC) in S1 and S3 species was 1.26 and 1.07 folds higher in 50?mM NaCl in comparison to control. In S2 species, total chlorophyll, chlorophyll_a and chlorophyll_b degradation were the highest (40.4%, 42.7%, 16.32%, respectively) in comparison to S3 (18.18%, 23%, 16.4%) and S1 (23.5%, 25%, 19.17%) species. In S3 and S1 species, the Chl_a/Chl_b ratio was maintained showing stabilisation of the net photosynthetic rate. Proline played a more important role than glycine betaine for salt tolerance of these bamboo species. On account of vegetative growth, proline accumulation and RWC, it is inferred that S1 and S3 species are salt tolerant while S2 is a sensitive species.

Abbreviations: SL: shoot length; RL: root length; NL: number of leaves; FW: fresh weight; RWC: relative water content; Chl_a: chlorophyll_a; Chl_b: chlorophyll_b; TC: total chlorophyll; GB: glycine betaine