Variations of tide and mean sea level (MSL) were studied during the period August 2000-March 2004 in the northern Gulf of Aqaba to detect the seasonal differences of tide records and tide components signals. The study...Variations of tide and mean sea level (MSL) were studied during the period August 2000-March 2004 in the northern Gulf of Aqaba to detect the seasonal differences of tide records and tide components signals. The study revealed seasonal cycle of the MSL in the northern Gulf, which was lower during summer than in winter due to the relative strong wind and higher evaporation during summer. The MSL during the year of 2003 Fwas the lowest comparing to the other years duing the study period which might be related to wind driven force and mixed layer depth. The statistical comparison analysis of the MSL among winters, springs and summers of the years 2000- 2004 exhibited significant difference values (p K1) and a lunar terdiurnal constituent (M3), respectively.展开更多
为探讨水-空气多介质条件下的封闭舱室水下噪声预报方法,以某10万吨级养殖工船的养殖水舱为研究对象,针对300~900 Hz频段,采用统计能量分析(Statistical Energy Analysis,SEA)法、有限元与边界元耦合法对养殖舱室结构进行辐射声场仿真...为探讨水-空气多介质条件下的封闭舱室水下噪声预报方法,以某10万吨级养殖工船的养殖水舱为研究对象,针对300~900 Hz频段,采用统计能量分析(Statistical Energy Analysis,SEA)法、有限元与边界元耦合法对养殖舱室结构进行辐射声场仿真与试验,将SEA法得到的结构响应速度作为边界元模型的边界条件,研究分析封闭舱室不同介质内的噪声贡献量。通过实船测试结果进行验证:数值仿真虽然存在误差但此差值在误差范围之内;在养殖舱内噪声分布方面,预报值与实测值呈现相同的分布趋势。研究方法对同类型及相似船舶舱内水下噪声预报有一定的参考意义。展开更多
Semi-enclosed sea basins have difficulty in recharging their waters due to limited communication with larger water bodies, with understandable consequences for their environmental status. This paper aims at the comput...Semi-enclosed sea basins have difficulty in recharging their waters due to limited communication with larger water bodies, with understandable consequences for their environmental status. This paper aims at the computational simulation of the hydrodynamic characteristics of the waters of the Pagasitikos Gulf (Greece), which has limited communication and water exchange with the Aegean Sea and is subject to intense environmental pressures The Estuary, Lake & Coastal Ocean 3d hydrodynamic Model (ELCOM 2.2) combined with its later version Aquatic Ecosystem Model-3d (AEM3D) were used for the simulation. The simulation included the topography of the area, the bay’s bottom geometry, atmospheric loadings, tides, the influence of the Coriolis force and boundary conditions. The hydrodynamic behaviour of the bay, water circulation, velocities at the surface and in depth, water recharge and residence time throughout the bay, density variation and other factors were examined to determine the impact of all these on the aquatic ecosystem.展开更多
为了能够利用遥感图像快速准确地提取围海养殖矢量信息,本文选取养殖水体、堤坝及育苗室等交错分布的海参围海养殖区域作为研究区域,根据研究区域Sentinel-2遥感影像的光谱特征,选用归一化差异水体指数(Normalized Difference Water Ind...为了能够利用遥感图像快速准确地提取围海养殖矢量信息,本文选取养殖水体、堤坝及育苗室等交错分布的海参围海养殖区域作为研究区域,根据研究区域Sentinel-2遥感影像的光谱特征,选用归一化差异水体指数(Normalized Difference Water Index,NDWI)、改进归一化差异水体指数(Modified Normalized Difference Water Index,MNDWI)和增强水体指数(Enhanced Water Index,EWI)三类水体指数,分别进行提取实验,利用同时期高空间分辨率的高分二号卫星(GF-2)影像作为参考,验证不同方法的提取精度,精度评价结果表明:相较MNDWI和EWI两类水体指数,NDWI的分类精度更高,且利用NDWI提取研究区域的围海养殖信息的效果更好,所以该方法可在养殖区域的动态监测和规划管理中发挥数据支撑作用。展开更多
文摘Variations of tide and mean sea level (MSL) were studied during the period August 2000-March 2004 in the northern Gulf of Aqaba to detect the seasonal differences of tide records and tide components signals. The study revealed seasonal cycle of the MSL in the northern Gulf, which was lower during summer than in winter due to the relative strong wind and higher evaporation during summer. The MSL during the year of 2003 Fwas the lowest comparing to the other years duing the study period which might be related to wind driven force and mixed layer depth. The statistical comparison analysis of the MSL among winters, springs and summers of the years 2000- 2004 exhibited significant difference values (p K1) and a lunar terdiurnal constituent (M3), respectively.
文摘为探讨水-空气多介质条件下的封闭舱室水下噪声预报方法,以某10万吨级养殖工船的养殖水舱为研究对象,针对300~900 Hz频段,采用统计能量分析(Statistical Energy Analysis,SEA)法、有限元与边界元耦合法对养殖舱室结构进行辐射声场仿真与试验,将SEA法得到的结构响应速度作为边界元模型的边界条件,研究分析封闭舱室不同介质内的噪声贡献量。通过实船测试结果进行验证:数值仿真虽然存在误差但此差值在误差范围之内;在养殖舱内噪声分布方面,预报值与实测值呈现相同的分布趋势。研究方法对同类型及相似船舶舱内水下噪声预报有一定的参考意义。
文摘Semi-enclosed sea basins have difficulty in recharging their waters due to limited communication with larger water bodies, with understandable consequences for their environmental status. This paper aims at the computational simulation of the hydrodynamic characteristics of the waters of the Pagasitikos Gulf (Greece), which has limited communication and water exchange with the Aegean Sea and is subject to intense environmental pressures The Estuary, Lake & Coastal Ocean 3d hydrodynamic Model (ELCOM 2.2) combined with its later version Aquatic Ecosystem Model-3d (AEM3D) were used for the simulation. The simulation included the topography of the area, the bay’s bottom geometry, atmospheric loadings, tides, the influence of the Coriolis force and boundary conditions. The hydrodynamic behaviour of the bay, water circulation, velocities at the surface and in depth, water recharge and residence time throughout the bay, density variation and other factors were examined to determine the impact of all these on the aquatic ecosystem.
文摘为了能够利用遥感图像快速准确地提取围海养殖矢量信息,本文选取养殖水体、堤坝及育苗室等交错分布的海参围海养殖区域作为研究区域,根据研究区域Sentinel-2遥感影像的光谱特征,选用归一化差异水体指数(Normalized Difference Water Index,NDWI)、改进归一化差异水体指数(Modified Normalized Difference Water Index,MNDWI)和增强水体指数(Enhanced Water Index,EWI)三类水体指数,分别进行提取实验,利用同时期高空间分辨率的高分二号卫星(GF-2)影像作为参考,验证不同方法的提取精度,精度评价结果表明:相较MNDWI和EWI两类水体指数,NDWI的分类精度更高,且利用NDWI提取研究区域的围海养殖信息的效果更好,所以该方法可在养殖区域的动态监测和规划管理中发挥数据支撑作用。
