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21.
1IN T R O D U C T IO N As a risingindustry,modern logisticpslaya vitalrolein thedevelopment ofurban economy . Meantime , many expertsin theworld are interestedin modern logistic.s Study on modern logisticsismostly focused on man - agement and program (HES…  相似文献   
22.
This paper presents the results on shaking table tests of half‐scale brick walls performed to investigate the effectiveness of newly developed Cu–Al–Mn superelastic alloy (SEA) bars in retrofitting of historical masonry constructions. Problems associated with conventional steel reinforcing bars lie in degradation of stiffness and strength, or pinching phenomena, under cyclic loading, and presence of large residual cracks in structures during and after intense earthquakes. This paper attempts to resolve the problems by applying newly developed Cu–Al–Mn SEA bars, characterized by large recovery strain, low material cost, and high machinability, as partial replacements for steel bars. Sets of unreinforced, steel reinforced, and SEA‐reinforced specimens are subjected to scaled earthquake excitations in out‐of‐plane direction. Whereas steel‐reinforced specimens showed large residual inclinations, SEA‐reinforced specimens resulted in stable rocking response with slight residual inclinations. Corresponding nonlinear finite element (FE) models are developed to simulate the experimental observations. The FE models are further used to examine the sensitivity of the response with respect to the variations in experimental conditions. Both the experimental and numerical results demonstrate the superiority of Cu–Al–Mn SEA bars to conventional steel reinforcing bars in avoiding pinching phenomena. Copyright © 2012 John Wiley & Sons, Ltd.  相似文献   
23.
The bulk ore carrier Apollo Sea sank south-west of Dassen Island off western South Africa in June 1994, oiling approximately 10 000 African penguins Spheniscus demersus, most of which were collected from Dassen Island. A total of 4 076 de-oiled penguins was released with flipper bands. From 1994 to 2005, follow-up research using re-sighting and capture-mark-recapture methods indicated that about 73% of the de-oiled penguins observed back at Dassen Island attempted to breed, and were thus successfully restored into the breeding population. For de-oiled breeders, the median interval between their first recorded sighting and first recorded breeding attempt was 11 months, indicating a short-term delay in restoration. At least 45% of the de-oiled breeders were still being re-sighted five years after their release, and a minimum of 4% survived into their ninth year. These results represent the most successful restoration estimates anywhere in the world. The proportion of de-oiled juvenile penguins re-sighted back at Dassen Island and recorded breeding was lower than that of birds in adult plumage. De-oiled non-breeders spent significantly more time along the shore and less time within breeding colonies than de-oiled breeders. The mean proportion of de-oiled breeders that abstained from breeding each year during the study period was greater than expected. There was a negative relationship between breeding and subsequent survival and breeding, suggesting a cost of reproduction for de-oiled birds.  相似文献   
24.
单频GPS短基线快速定位中的少数历元算法   总被引:2,自引:0,他引:2  
研究了短基线时利用少数历元的单频GPS载波相位观测值进行快速定位的一种算法。基于TIK-HONOV正则化原理,选择了一种具有物理意义的正则化矩阵,以减弱法矩阵的病态性。新算法只需解算几个历元的单频GPS相位数据,就可得到比较准确的模糊度浮动解及其相应的均方误差矩阵,用均方误差矩阵代替协方差阵,结合LAMBDA方法,可准确、快速地确定模糊度,最后得到基线向量的解。结合短基线算例,将少数历元算法与最小二乘估计的结果作了比较分析,得出了新解法的有效性。  相似文献   
25.
中国和欧盟土地利用规划环境影响评价对比研究   总被引:3,自引:0,他引:3  
土地利用规划环境影响评价是提高土地利用规划科学性,实现土地资源可持续利用、促进区域可持续发展 的重要工具。从当前我国土地利用规划环境影响评价借鉴国际尤其是欧盟经验中存在的问题出发,在总结我国及 欧盟国家土地利用规划环境影响评价特点的基础上,从土地利用规划及环境内涵、土地利用规划环境影响评价指 标体系和方法、土地利用规划环境评价的空间层次三个方面分析中国和欧盟土地利用规划环境影响评价的差异。 最后从中国土地利用规划环境影响评价的特点出发,提出合理界定土地利用规划与土地利用规划环境影响评价的 内容、建立中国土地利用规划特点的规划环境影响评价体系、发展规划导向的土地利用规划环境评价方法、加强多 学科、多部门合作以及公众参与的建议。  相似文献   
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