Based on the COHERENS model (a coupled hydrodynamic ecological model for regional and shelf seas), a numerical hydrodynamic model of the Hangzhou Bay, influenced by tide, regional winds and freshwater from the Yangtze River and the Qiantangjiang River was established. The Lagrangian particle tracking was simulated to provide tracer trajectories. For convenience, the modeling area was divided into 8 subdomains and the modeling focused on March (dry season) and July (wet season). Numerical simulation and analysis indicate that the tracer trajectories originated in different subdomains are quite different. Most particles released in the mouth of the bay move outside the bay quickly and reach the farthest place at 122.5°E; while particles released in the inner part of the bay mostly remain in the same subdomain, with only minor migrations in two opposite directions along the shore. The tracer experiments also indicate that the northwest region of the bay is an area where pollutant can easily accumulate in both wet and dry seasons, and that the southeast region of the bay is another area for pollutant to accumulate in dry season because it is the main path for the contaminant.
针对航空图像中的水面尾迹,提出了一种基于方向极傅里叶频谱二维主成分分析(Two-dimensional principal component analysis,2DPCA)的尾迹自动检测算法.该方法根据子图像的纹理方向,对傅里叶频谱进行极坐标变换,使得到的方向极傅里叶频谱具有平移和旋转不变性.相对于文献中对极频谱的直接划分作为纹理特征,本文对它进行一次列二维主成分分析,一次行二维主成分分析和两次二维主成分分析,实验结果表明本文方法具有更高的分类识别率,其中两次二维主成分分析的分类识别率最高.对40幅图像的测试结果表明,本文的方法能够有效地自动检测航空图像中的水面尾迹纹理。
A Lagrangian tracer model is set up for Hangzhou Bay based on Coupled Hydrodynamical Ecological model for Regional Shelf Sea (COHERENS). The study area is divided into eight subdomains to identify the dominant physical processes, and the studied periods are March (the dry season) and July (the wet season). The model performance has been first verified by sea-surface elevation and tidal current observations at several stations. Eight tracer experiments are designed and Lagrangian particle tracking is simulated to examine the impact of physical processes (tide, wind and river runoff) on the transport of passive tracer released within the surface layer. Numerical simulations and analysis indicate that: (1) wind does not change the tracer distribution after 30 days except for those released from the south area of the bay during the wet season; (2) the tide and the Qiantang River runoff are important for particle transport in the head area of the bay; (3) the Changjiang River runoff affects the tracer transport at the mouth of the bay, and its impact is smaller in the dry season than in the wet season.
Bentonite is a kind of natural clay with good exchanging ability. By exchanging its interlamellar cations with various soluble cations, such as quaternary ammonium cations and inorganic metal ions, the properties of natural bentonite can be greatly improved. In this study, hexadecyltrimethylammonium bromide (HDTMA), CaCl2, MgCl2, FeCl3, AlCl3 were used as organic and inorganic pillared materials respectively to produce several kinds of Ca-, Mg-, Fe-, Al-organo pillared bentonites. Sorption of reactive red X-3B on them was studied to determine their potential application as sorbents in wastewater treatment. The results showed that these pillared bentonites had much improved sorption properties, and that the dye solutions’ pH value had some effect on the performance of these inorgano-organo pillared bentonites. Isotherms of reactive X-3B on these pillared bentonites sug-gested a Langmuir-type sorption mechanism.
