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71.
????????????????????EDM??????????????????????3????????????????????????????????????????????????????????????????????????? 相似文献
72.
本文通过对大嶝码头拟建区沉积环境的详细,对比其几年来表层沉积物的变化状况,建立三维粒度参数图象,并结合柱状沉积物的参数演化,建立了该区域新近年代沉积环境演化模式。通过岸、滩的实地考察,采用海图对比分析,计算出拟建区岸滩宽度、高程的变化,并对其原因、泥沙运移规律进行探讨,计算出其年淤积强度,为该项工程建成后的防护问题提供依据。 相似文献
73.
针对如何优选出三频BDS最优载波相位线性组合观测量的问题,基于三频GNSS载波相位组合观测量理论,本文提出最优组合观测量选取的模糊聚类分析法。首先构建满足超宽巷组合和窄巷组合条件,且具有不同巷数、电离层数及噪声放大因子的三频BDS组合观测量,并假定各参数均为最优值的理论最优组合观测量;然后对满足条件的超宽巷组合和窄巷组合用模糊聚类分析法进行聚类排序;最后根据各组合观测量与假定的最优组合观测量聚为一类的先后顺序,确定三频BDS最优组合观测量的选取顺序。结果表明:模糊聚类分析法通过组合观测量的聚类排序,实现了最优组合观测量的筛选。无几何TCAR算法也验证了模糊聚类分析结果的正确性。 相似文献
74.
In this paper, Visual MODFLOW is used to simulate groundwater flow and transport within the study area based on a certain
scenario, assessing the leakage impact of a Sewage Plant accidental pool on groundwater using NH3-N as the assessment factor. In the model constructed, soil absorption and degradation was taken into account; the adsorption
process of NH3-N adopted the Langmuir equation and the degradation was simplified as a first-order dynamic reaction. The leakage process
was defined as a recharge with contaminants in the case that where there are two accidents happening to the Sewage Plant within
a one month interval. The result of the model indicated that the NH3-N concentration of groundwater increased sharply when the Sewage Plant was malfunctioning. The peak of NH3-N concentration under the accident pool was about 8.0 × 10−5 mg/L at the first accident. When the second accident happened, the NH3-N concentration increased to a maximum of about 1.1 × 10−4 mg/L. At a location of about 20 m from the accident pool, the concentration declined to about one sixth of the center, which
demonstrated that the NH3-N concentration increase caused by leakage of the accident pool was little, and the spatial influence also was small. The
paper provides a method of dealing with the transport of physically and chemically reactive substances in groundwater with
Visual MODFLOW and assessing the Sewage Plant accident pool leakage impact on groundwater quantitatively. 相似文献
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76.
通过深层次构造岩中不同粒度矿物多晶条带塑性流动的比较和形成机理的探讨,得出矿物多晶条带的流度规律:在深层次构造岩中加工状态下生成的数种矿物多晶条带共生时,其晶粒较小着塑性流动的流度较大。结合单矿物多晶条带的粒度规律得出:在深层次构造岩中由动态重结晶所生成的数种单矿物多晶条带共生时,其中脆-韧性转化点温度较高的矿物,其多晶条带的塑性流动的流度较大。根据温压条件由低至高矿物的脆-韧性转化序列和岩石圈大陆部分各圈层的主要组成矿物,可知岩石圈大陆部分各圈层的塑性流动具有协调性。 相似文献
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79.
Evaluation of the sound-structure interaction is important for effective control of noise and vibration in structural acoustic systems. Cracked elastic structure-sound interaction problems are studied by employing the hybrid fractal FEM and BEM. The degrees of freedom of the system can be reduced greatly through adopting fractal FEM in discretizing the cracked elastic structure; while the exterior acoustic field is calculated by BEM, which automatically satisfies Sommerfeld‘s radiation condition. Numerical examples are given and show that the resonant frequencies of the structure-acoustic coupled system decrease as the depth of the crack increases, and that the crack has a significant effect on the acoustical field in the vicinity of the crack tip. 相似文献
80.
Minhan Dai Weidong Zhai Wei-Jun Cai Julie Callahan Bangqin Huang Shaoling Shang Tao Huang Xiaolin Li Zhongming Lu Weifang Chen Zhaozhang Chen 《Continental Shelf Research》2008
We observed a phytoplankton bloom downstream of a large estuarine plume induced by heavy precipitation during a cruise conducted in the Pearl River estuary and the northern South China Sea in May–June 2001. The plume delivered a significant amount of nutrients into the estuary and the adjacent coastal region, and enhanced stratification stimulating a phytoplankton bloom in the region near and offshore of Hong Kong. A several fold increase (0.2–1.8 μg Chl L−1) in biomass (Chl a) was observed during the bloom. During the bloom event, the surface water phytoplankton community structure significantly shifted from a pico-phytoplankton dominated community to one dominated by micro-phytoplankton (>20 μm). In addition to increased Chl a, we observed a significant drawdown of pCO2, biological uptake of dissolved inorganic carbon (DIC) and an associated enhancement of dissolved oxygen and pH, demonstrating enhanced photosynthesis during the bloom. During the bloom, we estimated a net DIC drawdown of 100–150 μmol kg−1 and a TAlk increase of 0–50 μmol kg−1. The mean sea–air CO2 flux at the peak of the bloom was estimated to be as high as ∼−18 mmol m−2 d−1. For an average surface water depth of 5 m, a very high apparent biological CO2 consumption rate of 70–110 mmol m−2 d−1 was estimated. This value is 2–6 times higher than the estimated air–sea exchange rate. 相似文献