Exploring relationships between recruitment of European hake (Merluccius merluccius L. 1758) and environmental factors in the Ligurian Sea and the Strait of Sicily (Central Mediterranean)

This paper explores the relationships between the spatial patterns of the distribution of the young hakes of the year (YOY) and the oceanographical features in two areas of the Central Mediterranean (the Ligurian Sea and the Strait of Sicily), characterised by the occurrence of straits and channels. Comparative and correlative approaches were used to investigate coupling between biological and physical patterns. Density indices of the YOY were derived from annual trawl surveys from 1994 to 2004 in spring and autumn. Mean patterns of the YOY distributions were compared with the mesoscale oceanographical features reported in literature. No evident trends in recruitment strength were found in either areas. Inter-annual variability in YOY abundance in the Ligurian Sea was higher than in the Strait of Sicily. The location of nursery grounds in the study areas coincides with zones of relatively higher production, where upwelling and other enrichment processes regularly occur. The presence of predictable eddies and the frontal systems play a major role in the localization of nursery areas in the Strait of Sicily, maintaining their stable position throughout the years. The strongest transport of southern waters from the Tyrrhenian to the Ligurian Sea, due to the East Corsica Current, which is negatively correlated to winter North Atlantic Oscillation, is associated with the highest abundance of hake recruits in the nurseries of the Northern Ligurian Sea.     

建设项目全寿命周期一体化管理模式探讨

文章针对传统项目管理模式的弊端,结合当前建设项目发展的趋势,从项目全寿命周期的角度出发,对建设项目全寿命周期一体化管理模式进行了初步探讨。同时分析了此模式下的项目运作流程、组织实施和信息一体化平台,旨在通过寻求一种合理有效的管理模式,适应建筑项目发展的现实需要,也为同类项目问题的解决提供参考。     

数据库体系化环境及若干问题研究

数据库体系化环境能够完整、细致地反映企业中的数据组织与处理.本文结合实际应用案例,提出了建立企业数据库体系化环境的实施策略,并讨论了相关问题的处理.     

基于模糊贝叶斯网络的山区高速铁路桥梁运营风险评估

针对山区高速铁路桥梁风险情况复杂且影响巨大的特点,提出基于模糊贝叶斯网络,建立山区高速铁路桥梁运营风险评估模型。将山区高速铁路桥梁风险损失划分成3类,分别列出各类损失的风险因素,构建桥梁运营风险概率评估的贝叶斯网络,通过专家调查法统计出桥梁风险因素的概率等级分布,并根据链式传递规则计算出风险事故的概率等级分布。然后,结合风险矩阵对桥梁运营风险水平进行评估。最后,利用该方法分析贵广高速铁路上云阳双线特大桥的运营风险。结果表明,建立的模型计算过程简便,评价结果符合实际,具有较高的实用性。     

浅谈运营高速公路边坡石方爆破施工方法

运营高速公路上边坡石方爆破是工程建设领域的一个难题,常规爆破必然危及高速公路自身结构安全和行车安全。文章介绍了石方普通爆破、孔外延时孔间微差定向松动爆破、劈裂机静态爆破三种不同的爆破方式,并针对运营高速公路实际,提出结合运用孔外延迟孔间微差定向松动爆破和劈裂机静态爆破两种爆破方法,能有效地对运营中的高速公路上边坡石方进行安全爆破。