波浪作用下的海底管道溢油扩散运移规律

为了最大程度减少溢油事故造成的环境污染及经济损失,对海底管道溢油扩散行为的影响因素进行研究.首先,利用流体力学软件建立了波浪条件下的二维有风模型,并进行了验证.其次,通过二维有风模型进行溢油模拟,分析讨论了原油密度、海浪波长、水面风速等因素对溢油扩散的影响.研究结果表明:1)建立的二维有风模型模拟结果比现有文献中模型更...     

清代皇家园林“南风”主题景点的 园景构筑与文化内涵阐释

《南风歌》最早记载于中国先秦典籍中，全文蕴含 了虞舜歌“南风”以煦育百姓、顺应天时物性而治天下的美好 象征。随着《南风歌》的传颂，以该典故为主题问名的建筑景 点大量出现于中国古典园林尤其是清代皇家园林中。首先考辨 了“舜歌南风”典故的历史源流，挖掘其在流传过程中所衍生 的文化内涵。继而对以“南风”主题问名于我国古代园林建筑 的历史面貌进行爬梳，重点以清代皇家园林中的“南风”主题 景点为例，围绕“薰风解愠”和“对时育物”2个角度探析其 在园景构筑与文化内涵阐释层面对“南风”主题的表达。结论 证明“南风”意象主题景点是中国古典园林尤其是清代皇家园 林中的一类重要景观类型。     

Analysing inefficiency in a non-parametric spatial-dynamic by-production framework: A k-nearest neighbour proposal

This paper accounts for spatial effects by benchmarking farms against their k-nearest neighbours (KNN) and measuring their inefficiency in a non-parametric dynamic by-production setting. The optimal number of neighbours $k$ against which farms are compared corresponds to the value of $k$ that maximises the Moran I test for spatial autocorrelation of the good and the bad output of the farms' two sub-technologies. The inefficiency scores for farms' good output, variable inputs, investments and bad outputs are then computed and compared with those calculated based on a global technology, which benchmarks all farms together. The application focuses on an unbalanced panel of specialised Dutch dairy farms over the period 2009–2016 that contains information on their exact geographical locations. The results suggest that the inefficiency scores exhibit statistically significant differences between the KNN and the global model. Specifically, the inefficiencies are generally deflated when a KNN technology is considered, suggesting that ignoring spatial effects can overestimate inefficiency.