概括平差模型的解法探讨

分析了概括平差模型系数矩阵可能出现非列满秩情况的原因,研究了如何使系数矩阵为列满秩矩阵,避免了系数矩阵为非列满秩时的复杂解算过程。     

Shape optimization of two-dimensional cavitators in supercavitating flows, using NSGA II algorithm

The reduction of energy consumption of high speed submersible bodies is an important challenge in hydrodynamic researches. In this paper, shape optimization of two-dimensional cavitators in supercavitating flows is studied. A two dimensional supercavitation potential flow passes a symmetric two dimensional cavitator, which is placed perpendicular to the flow in a channel of infinite length and immediately a cavity is formed behind the cavitator. This is because of the generation of a gas or vapor cavity between the body and the surrounding liquid due to the change in a high speed flow direction passing the cavitator. Drag force acting on this supercavitating body dictates the thrust requirements for the propulsion system, to maintain a required cavity at the operating speed. Therefore, any reduction in the drag force, by modifying the shape of the cavitator, will lead to decrease this force. This study concentrates on the optimization of two dimensional cavitators in order to decrease drag coefficient for a specified after body length and velocity in a potential flow. To achieve this goal a multi-objective optimization problem is defined to optimize cavitator shapes in supercavitating flow. The so-called NSGA II (Non-dominated Sorting Genetic Algorithm) algorithm is used as an optimization method. Design parameters and constraints are obtained according to supercavitating flow characteristics and cavitator modeling and objective functions are generated using Linear Regression Method. The obtained results are compared with other classic optimization methods, like the weighted sum method, for validation.     

Silver in Tokyo Bay estuarine waters and Japanese rivers

Dissolved and particulate concentrations of silver in Tokyo Bay estuarine waters and Japanese rivers were determined in this study. The dissolved silver concentrations in the surface water of Tokyo Bay range from 5.9 to 15.1 pmol kg⁻¹, which is comparable to those in the surface water of the Japan Sea, but two or three times higher than those in the surface water of the open ocean. However, elevated concentrations of dissolved silver are not found in Tokyo Bay compared with those in other highly urbanized estuaries, such as San Francisco Bay (20∼243 pmol kg⁻¹). In the Tokyo Bay estuary, silver typically exhibits non-conservative mixing behavior, which is a common feature in the other estuaries reported previously. Dissolved silver concentrations decrease with salinity from the rivers to the mouth of Tokyo Bay. Silver is efficiently scavenged by suspended particulates, as evidenced by the high conditional distribution coefficients for silver throughout the estuary (log K_d > 5.0 ± 0.6). The silver fluxes into Tokyo Bay via inflowing rivers and atmospheric deposition were estimated as 83 kg y⁻¹ and 15 kg y⁻¹, respectively. A simple budget calculation shows that the silver supplied from rivers and atmosphere must be rapidly scavenged within the Tokyo Bay estuary.     

Optical properties of the red tide in Isahaya Bay,southwestern Japan: Influence of chlorophyll a concentration

Remote sensing reflectance [R _rs(λ)] and absorption coefficients of red tides were measured in Isahaya Bay, southwestern Japan, to investigate differences in the optical properties of red tide and non-red tide waters. We defined colored areas of the sea surface, visualized from shipboard, as “red tides”. Peaks of the R _rs(λ) spectra of non-red tide waters were at 565 nm, while those of red tides shifted to longer wavelengths (589 nm). The spectral shape of R _rs(λ) was close to that of the reciprocal of the total absorption coefficient [1/a(λ)], implying that the R _rs(λ) peak is determined by absorption. Absorption coefficients of phytoplankton [a _ph(λ)], non-pigment particles and colored dissolved organic matter increased with increasing chlorophyll a concentration (Chl a), and those coefficients were correlated with Chl a for both red tide and non-red tide waters. Using these relationships between absorption coefficients and Chl a, variation in the spectrum of 1/a(λ) as a function of Chl a was calculated. The peak of 1/a(λ) shifted to longer wavelengths with increasing Chl a. Furthermore, the relative contribution of a _ph(λ) to the total absorption in red tide water was significantly higher than in non-red tide water in the wavelength range 550–600 nm, including the peak. Our results show that the variation of a _ph(λ) with Chl a dominates the behavior of the R _rs(λ) peak, and utilization of R _rs(λ) peaks at 589 and 565 nm may be useful to discriminate between red tide and non-red tide waters by remote sensing.     

不同结构形式潜堤上的随机波浪运动

潜堤在海岸保护和促潍保淤中具有重要的意义。工程效益和经济投入受到潜堤结构形式和高度的影响。基于RANS方程和流体体积（VOF）方法的模型,计算不同潜堤上的波浪运动。潜堤形式包括矩形结构、梯形结构、半圆结构和槽形结构。模拟了不规则波越堤时波浪的破碎特征、破波类型以及波高的变化。通过分析流场和波高分布的变化,得到潜堤上波能散耗的规律,并且得出最优潜堤结构形式。讨论了相对堤顶高度、破碎点位置、相对堤顸宽度、波陡和潜堤结构形式等对波能耗散的影响。     

落球法测量高频振动对淤泥的液化效果

为了提高疏浚工程中管道输送淤泥的效率,对淤泥预处理技术——高频微幅振动液化技术进行了初步研究。主要介绍了落球法测量淤泥粘滞系数的实验,对不同性质的淤泥分别进行实验,根据距离振动棒不同位置的小球的沉降速度求出相应位置的粘滞系数,并将其进行比较,获得液化影响范围。实验结果表明,高频振动对于粉砂质淤泥具有良好的液化效果。     

基于公平性的水环境容量分配研究——以沱江流域为例

公平与效益是容量分配的两个重要原则.在我国目前采用的水环境容量无偿分配方式下,公平原则是需遵循的首要原则,在公平的基础上追求效益.以沱江流域为对象,综合考虑涉及区域的社会、经济、自然等客观因素,筛选指标确定系数对流域容量进行分配.应用经济学中衡量收入公平的基尼系数概念,对分配结果的公平性进行评估,给出综合体现社会性、经济性和历史性的水环境容量分配方案.     

The effect of current and wave on whitecap coverage via relative speed： the Atlantic Ocean case

Whitecapping plays an important role in many air-sea exchange and upper ocean processes. Traditionally, whitecap coverage is parameterized as a function of wind speed only. At present, the relative speed of ocean current to wind is considered to be important in the air-sea exchange parameterization which is the function of wind speed only. In this paper, the effects of ocean surface velocity (current velocity and wave induced velocity) and the wave parameters on whitecap coverage through relative speeds are investigated, by applying a 2-parameter whitecap coverage model to the Atlantic Ocean. It is found that the impacts of both current and wave on whitecap coverage are considerable in the most part of the Atlantic Ocean. It is interesting that the effect of wave is more significant than that of current.     

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青岛陆上观测点的气溶胶光学厚度特征分析及与渤海气溶胶光学厚度的比较

阐述了气溶胶散射对太阳光衰减的影响和对观测数据的统计分析.作者使用手持式五波段太阳光度计和臭氧监测仪对青岛崂山区陆域和渤海海域的大气衰减进行了较长时间的观测.分析表明,对可见光和近红外波段电磁渡的大气衰减贡献最大的是气溶胶散射,气溶胶散射的光学厚度随波长的增大而减小,但是它在大气总光学厚度中占的比例随波长的增大而增加.在青岛崂山区冬季,对应于440nm波长的气溶胶散射光学厚度主要分布在0.4～0.6和1.5～1.6区间,浑浊度系数α主要分布在0.15～0.45区间,埃斯特朗指数β主要分布在1.0～1.4区间.从时间上看,α和β在1d内的变化不大,但逐日变化非常显著.与晴天相比,青岛崂山区冬季雾天的气溶胶散射光学厚度增加了大约一倍,较大的浑浊度系数和较小的埃斯特朗指数表明,雾天的大气具有气溶胶散射的光学厚度大、粒子浓度大和粒径尺度大的特点.通过与海上观测数据的比较可见,青岛崂山区陆地冬季在雾天时的气溶胶分布与渤海夏季时相似,青岛崂山区陆地冬季在晴天无云时的气溶胶分布与渤海秋季时相似.