考虑震损的混凝土框架结构改进建模方法

为准确描述震后结构损伤的影响,提出了损伤构件的定量分析方法及震损结构的改进建模方法.首先,从骨架曲线退化及滞回规则退化两方面定义了损伤构件的性能退化指数;然后,基于Park-Ang模型与Kunnath模型,采用统计回归分析方法提出了损伤构件恢复力模型,并对其准确性进行了验证;最后,应用该恢复力模型对震损框架结构进行弹塑性分析.结果 表明:采用Park-Ang模型和Kunnath模型得到的损伤构件恢复力模型均具有较高的准确性;对于所研究的2种构件,滞回曲线力峰值的理论值和试验值误差均小于10％;向完好结构输入组合地震波,向震损结构输入单一地震波,各层位移时程曲线吻合良好,说明采用该恢复力模型进行震损结构建模能够准确分析震损程度及分布对结构抗震性能的影响.     

Impact of gamma radiation and salinity on growth and K+/Na+balance in two populations of Medicago sativa(L.)cultivar Gabès

The perennial Medicago sativa cv.Gabès is widely grown on saline soils in Tunisian oases.Morphological and physiological analyses of two populations(Mareth and Gannouch)were conducted in order to study the effect of salinity and gamma radiation(350 Gy)inter-action on two populations of this species.It has been shown that the two irradiated populations of Medicago sativa are fairly tolerant to salt at growth phase compared to the non-irradiated.Exposure to gamma irradiation(350 Gy),alone or in combination with salt stress,increased significantly (p<0.00 1)shoot number,stem height and chlorophyll b pigment especially for the Gannouch population,while no change occurred for the Mareth population.The presence of salt to 9 g/1 affected significantly the root biomass and induced a reduc-tion of shoot development of both control and irradiated alfalfa populations.For all treatments,plants of two populations remained able to produce and to allocate dry matter to the different organs.The survey of Na+/K+ratio showed that the growth of the aerial organs of two non-irradiated populations was at least determined by a selectivity in favour of the K+ions r2=0.97 and r2=0.59 for Mareth and Gannouch non-irradiated populations,respectively).However,the rather weak correlation detected for the irradiated populations,par-ticularly for the irradiated Gannouch.seems to be the consequence of the effect of irradiation that improved potassium availability.essential element for growth and development.Results also showed that the two irradiated populations,especially the Mareth,accumu-lated Na+ions in its photosynthetic organs.This accumulation was associated with an improvement of foliar water content at a level of salinity around 5 g/1.Such a mechanism reflects probably an inclusive behaviour of the plants and a good aptitude to use the dominant ions(Na+)for the osmotic adjustment.However,the non-irradiated populations are unable to adjust their internal osmotic potential.Consequently,irradiated plants have probably adapted to the osmotic stress by either closing their stomata or increasing the osmotic pressure of the leaf cells.     

一种克服机械共振的功率放大电路

许多驱动机械装置的马达的功放电路，由于受到机械共振频率的限制，不能高速运行．本电路采用陷波器，对于机械共振频率进行限制，保证驱动系统在高速运行时的稳定性．     

Isolation of alkaloids fromAthrotaxis selaginoides

Summary A novel series of alkaloids has been obtained from the Tasmanian plantAthrotaxis selaginoides, the first to be isolated from the plant family Taxodiaceae.     

Degradation of phenylalanine in the presence of hydrogen peroxide.

UV-irradiation of phenylalanine by 253.7 nm light in the presence of hydrogen peroxide formed 5 ninhydrin reactive products and ammonia. Four of them were identified as aspartic acid, serine, alanine and lysine.     

低秩矩阵恢复模型改进及其在石油测井中的应用

传统的低秩矩阵恢复模型在去噪过程中通过将观测矩阵分解为低秩部分和稀疏部分达到噪声去除的目的,但该模型要求噪声矩阵必须是稀疏的。然而石油测井所获得的数据中噪声来源复杂,并不能完全保证噪声分布满足稀疏性的要求,使该模型在去噪时表现出一定的局限性,去噪效果不稳定,进而导致后续的数据处理准确率降低。为此,提出将加权范数的思想应用于传统的低秩矩阵恢复模型中,并在惩罚项中将F范数与待恢复矩阵的核范数相结合,构造改进的低秩矩阵恢复模型,使其能够在保证解的稳定性的同时,可以更好地挖掘观测矩阵的低秩性以及增强稀疏矩阵的稀疏性。通过非精确的拉格朗日乘子法分别对改进前后的模型进行求解,并对两种模型去噪后的测井数据分别采用支持向量机(SVM)和相关向量机(RVM)进行油气层识别,结果表明经改进的低秩矩阵恢复模型去噪后的测井数据在保证了油气层识别效率的同时,识别准确率上有了明显提升。