基于分形融合FBM的海浪模型研究

海浪模拟作为非线性模拟代表方向之一。国内外研究划分为两种派系,由此产生的各种单一模型都不能满足逼真、快速和可控的需求。提出了一种新的改进海浪模型。该模型融合了分形的分数布朗运动曲面模型,以及经典的线性叠加浪谱Gerstner模型;并通过两种模型产生高度场的权重比值,来对海浪模拟进行调节和控制。实验证明,新模型生成的海浪逼真度高,能够产生大面积海面,改变视点,可以通过人为参数设定改变海浪海况;与经典模型相比,具有计算效率好、逼真度高、可控性好的优点,说明新模型在海浪模拟模型研究方面具有一定的改善。     

基于人工神经网络的自航浮标测波方法可行性

海洋波浪会对船舶营运和安全产生不利影响,实时准确的随船海浪监测对绿色智能船舶及航行安全至关重要.利用船舶运动反演遭遇海浪信息是一种重要的随船海浪监测手段,具有成本低、时空分辨率高等诸多优点,受到广泛关注.针对现有船舶运动反演海浪模型存在的不足,提出了一种基于人工神经网络(Artificial Neural Networ...     

海浪磁噪声背景中动目标航空磁异常检测算法

针对传统正交基分解检测算法不适用于海浪磁噪声背景下动目标检测航空磁异常检测问题,提出了基于自适应海浪磁噪声抑制的动目标航空磁异常检测算法.基于Weaver海浪磁场模型提出以观测海洋风浪谱生成的风浪位移信号作为参考噪声输入,利用最小均方自适应滤波算法对海浪磁噪声进行估计和抑制.基于传统正交基函数分解算法和动目标的航空磁异常探测模型,设计了动目标航空磁异常检测算法.仿真实验数据处理结果表明,该算法具有较好的海浪磁场抑制能力,能极大地提高海浪磁噪声条件下微弱磁异常动目标的检测能力.     

基于频谱的海浪实时模拟

基于海浪谱皮尔逊一莫斯科维奇谱(P-M谱),提出了一种新的海浪实时模拟方法,该方法考虑了海水深度对波形的影响,并通过纹理映射、材质设置、光照、色彩融合等渲染技术实现了海浪造型及动态显示.实验表明该方法在波浪模拟的简易性、实时性与真实感方面均取得不错的效果,适合各种深度的海洋波浪模拟.     

海洋动力系统数值模式体系及海浪-环流耦合理论

从系统科学的观点出发,把海洋运动按照时空尺度分解成小尺度(以海浪为代表)子系统、中尺度(以内波为代表)子系统、大尺度(以大洋波动和环流为代表)子系统,并把海洋和大气之间通过近海面海洋大气层进行相互作用的部分称为近海面海洋大气边界层子系统。考虑各子系统之间的相互作用,提出了从海洋动力系统观点出发发展海洋数值模式体系的科学思路。通过考虑海浪对环流的垂向混合作用,将海浪的运动混合作用解析表达为可以通过海浪数值模式直接计算的海浪谱形式,建立了海浪-环流耦合理论。这一理论不仅将普林斯顿环流模式全球上100米的模拟海温与Levitus资料之间的平均相关系数从0.58提高到了0.76,而且加深了我们对中国近海海洋环流系统的理解,同时对气候模式热带偏差这一共性问题有显著改善。该理论对海洋环境预报和全球气候变化预测具有重要意义。     

非线性海浪载荷谱的研究

应用Hemite多项式.对非线性海浪阻力进行了分析.研究表明.非线性阻力线性化后.计算值比实际值小.其均方误差约为10％.这对于海洋结构物的设计和使用来说.将是不安全的.为了改进非线性海浪阻力的计算方法.本文首次提出了非线性阻力谱传递函数的概念.并通过数值计算.给出了该函数的经验公式.为非线性海浪阻力的计算提供了简便可行而又比较精确的计算方法.     

自由水面式半圆体开孔海洋结构物水动力性能实验研究

提出了自由水面式半圆体开孔这一海洋结构物的新型式,并对该型式结构物进行了不同水深、不同模型浸水深度,以及不同波高和周期下系统的规则波及不规则波的模型实验研究.对结构物的透射系数Ct、反射系数Cr以及能量耗散系数Cl进行了系统总结.通过研究发现自由水面式半圆体开孔海洋结构物的消波性能随着模型相对水深以及相对板宽的增加而增强;并且该结构具有较小的波浪反射率以及较好的能量耗散效果,适合在海岸基础设施中推广建造.     

应用夏波希模型估算海洋石油钢结构疲劳寿命的试验研究

基于损伤力学的理论和方法,书夏波希疲劳损伤数学模型应用于海洋石油钢结构的疲劳寿命估算.对国产海洋用钢15MnVNb的表面裂纹试样在拉-弯载荷联合作用下,进行了疲劳损伤试验,提出了损伤因子的测量方法及疲劳损伤特性参数的计算方法.根据常幅疲劳试验结果,计算出了15MnVNb材料损伤特性参数,并给出了疲劳寿命估算的表达式.通过模拟海浪载荷的随机疲劳试验,验证了夏波希模型.疲劳寿命的理论计算结果与试验结果的相对误差约为7％,说明两者吻合较好.     

基于Gerstner函数和JONSWAP海浪谱的海浪仿真

针对单一海浪仿真方法在不同场景应用的局限性,提出了基于Gerstner函数与JONSWAP海浪谱相结合的海浪仿真方法,实现了不同波浪强度下的海浪建模.选取了Gerstner函数方程组作来海浪构造模型,并将其扩展成三维形式模拟海浪的细节和真实度;为了控制海浪模型并实现海浪的随机性、多变性、真实性,采用了JONSWAP海浪谱获取控制海浪模型的参数,进而建立了海浪仿真模型;针对多组海浪谱的频谱参数进行海浪仿真和不同海浪建模方法的海浪仿真,实验结果表明,所提方法有效性和实用性较好,真实度高,并适用于多种海浪场景.     

基于Gerstner函数和JONSWAP海浪谱的海浪仿真

针对单一海浪仿真方法在不同场景应用的局限性,提出了基于Gerstner函数与JONSWAP海浪谱相结合的海浪仿真方法,实现了不同波浪强度下的海浪建模.选取了Gerstner函数方程组作来海浪构造模型,并将其扩展成三维形式模拟海浪的细节和真实度;为了控制海浪模型并实现海浪的随机性、多变性、真实性,采用了JONSWAP海浪谱获取控制海浪模型的参数,进而建立了海浪仿真模型;针对多组海浪谱的频谱参数进行海浪仿真和不同海浪建模方法的海浪仿真,实验结果表明,所提方法有效性和实用性较好,真实度高,并适用于多种海浪场景.     

O3和海温对七月中、低纬环流的影响

在原球圈范围的Ｐ－σ坐标模式中加入了Ｏ３和海洋混合层的影响，对７月中、低纬流场进行了数值模拟试验．第１种方案中包含了Ｏ３，第２种方案既包含了Ｏ３又引入了海洋混合层．将这两种方案与原方案（不包含Ｏ３和海洋混合层）流场的模拟结果作对比分析发现１、２方案模拟结果比原方案更接近实况，特别是第２种方案模拟效果更加理想．表明Ｏ３和海洋混合层对大气环境的影响是重要的，它不仅直接影响到海洋，对陆地也有重要影响．其影响不只是局限于大气的低层，对高层也是显著的     

A modeling study of relation between cloud amount and SST over western tropical pacific cloudy regions during TOGA COARE

The relationship between cloud amount and sea surface temperature (SST) over western tropical Pacific cloudy regions during TOGA COARE is investigated based on hourly grid simulation data from a two-dimensional coupled ocean-cloud resolving atmosphere model. The model is forced by the large-scale vertical velocity and zonal wind observed and derived from TOGA COARE for a 50-day period. The cloud amount becomes smaller when the ocean surface gets warmer, which is similar to previous relations obtained from observational analyses. As SST increases, the atmospheric temperature increases whereas the surface sensible heat flux decreases. The atmospheric water vapor is not sensitive to SST whereas the surface evaporation flux decreases as SST increases. These indicate that the oceanic effects do not play an important role in determining atmospheric heat and water vapor budgets. The cold atmosphere produces a larger amount of ice clouds that cover a larger area than the warm atmosphere does. The large amounts of ice clouds lead to cooling of the ocean surface through reflecting large amount of solar radiation back to the space. Thus, the negative correlation between the cloud amount and SST only accounts for the important atmospheric effects on the ocean.     

Observational evidence for an ocean heat pump induced by tropical cyclones

Ocean mixing affects global climate and the marine biosphere because it is linked to the ocean's ability to store and transport heat and nutrients. Observations have constrained the magnitude of upper ocean mixing associated with certain processes, but mixing rates measured directly are significantly lower than those inferred from budget analyses, suggesting that other processes may play an important role. The winds associated with tropical cyclones are known to lead to localized mixing of the upper ocean, but the hypothesis that tropical cyclones are important mixing agents at the global scale has not been tested. Here we calculate the effect of tropical cyclones on surface ocean temperatures by comparing surface temperatures before and after storm passage, and use these results to calculate the vertical mixing induced by tropical cyclone activity. Our results indicate that tropical cyclones are responsible for significant cooling and vertical mixing of the surface ocean in tropical regions. Assuming that all the heat that is mixed downwards is balanced by heat transport towards the poles, we calculate that approximately 15 per cent of peak ocean heat transport may be associated with the vertical mixing induced by tropical cyclones. Furthermore, our analyses show that the magnitude of this mixing is strongly related to sea surface temperature, indicating that future changes in tropical sea surface temperatures may have significant effects on ocean circulation and ocean heat transport that are not currently accounted for in climate models.     

利用亮度特性的形象复原

提示了从明暗图像中复原三维信息的新方法.Photometric Stereo Method(PSM)一般以直接照明为前提.在研究中采取PSM间接扩散照明,适用了漫反射成分和全反射成分所构成的混性反射模型.在混性反射模型和间接扩散照明的条件下,物体面的亮度分布比率与表面法线向量的关系中导出了反射函数.接着把得出的反射函数带入到输入在相机的物体像素亮度,从而得到发现向量.利用这个发现向量可以复原物体的三维形象.物体的三维形象复原是通过物体表面粗糙,表面反射率,还有物体像素亮度而得出的表面法线向量来求出的.因为所提示的研究采用了亮度参照表,形象复原的速度既快又准确.反射函数被广泛定义,对具有多种形态表面特性的物体适用可行.     

Calculation of non－mono chromatic reflectance of Co／Sb multilayer

It is well known that the structure defects, such as the interfacial roughness, interdiffusion and chemical reaction at interface, can degrade the optical properties for soft X-ray multilayer[1—5]. For example, the interfacial rough-ness can lead to a loss of spectral reflectance, which has been investigated for many years, and number theories for the scattering of electromagnetic radiation by interfacial roughness have been formulated[6,7]. In addition, the fluc-tuation of the period can als…     

Aerosols implicated as a prime driver of twentieth-century North Atlantic climate variability

Systematic climate shifts have been linked to multidecadal variability in observed sea surface temperatures in the North Atlantic Ocean. These links are extensive, influencing a range of climate processes such as hurricane activity and African Sahel and Amazonian droughts. The variability is distinct from historical global-mean temperature changes and is commonly attributed to natural ocean oscillations. A number of studies have provided evidence that aerosols can influence long-term changes in sea surface temperatures, but climate models have so far failed to reproduce these interactions and the role of aerosols in decadal variability remains unclear. Here we use a state-of-the-art Earth system climate model to show that aerosol emissions and periods of volcanic activity explain 76 per cent of the simulated multidecadal variance in detrended 1860-2005 North Atlantic sea surface temperatures. After 1950, simulated variability is within observational estimates; our estimates for 1910-1940 capture twice the warming of previous generation models but do not explain the entire observed trend. Other processes, such as ocean circulation, may also have contributed to variability in the early twentieth century. Mechanistically, we find that inclusion of aerosol-cloud microphysical effects, which were included in few previous multimodel ensembles, dominates the magnitude (80 per cent) and the spatial pattern of the total surface aerosol forcing in the North Atlantic. Our findings suggest that anthropogenic aerosol emissions influenced a range of societally important historical climate events such as peaks in hurricane activity and Sahel drought. Decadal-scale model predictions of regional Atlantic climate will probably be improved by incorporating aerosol-cloud microphysical interactions and estimates of future concentrations of aerosols, emissions of which are directly addressable by policy actions.     

Ocean primary productivity estimation of China Sea by remote sensing

Ocean primary productivity is a key parameter in the research of globalcarbon cycle, ocean biological resources, and in evaluation of the feature and quality of ocean biological environment. Traditional shipboard measurement which is costly and time-consuming is impossible to obtain the spatial and temporal information on primary productivity on a large scale in a short period of time. Satellite remote sensing is an effective strategy to acquire the ocean information in near real time. Here we propose a model special for China Sea based on the concept of primary productivity using in situ primary productivity and environmental data from 1984 to 1990, and discuss every modeling parameter which can be retrieved by remote sensing in detail. The reliability of this model is tested by in situ data, and the comparison of other primary productivity models is made. We also analyze the temporal and spatial distribution of China Sea primary productivity in 2000. From our analysis the satellite remote sensing data have been proved very useful for ocean primary productivity study.     

β计数法测定水环境中的131I

131I是核医学应用中非常重要的核素,同时也是核泄漏事故中释放的主要裂变核素之一,其准确测定对于环境保护具有非常重要的意义.本文详细描述了不同水环境中的131I的β计数测定法,并对海水、放射性废水等不同水环境样品进行了检测,结果表明:1)本研究中碘的化学回收率为85.39%～94.47%,平均值为90.90%;2)海水样品平行样中131I的体积比活度为0.673 4～0.735 1 Bq/m3,放射性废水平行样中131I的体积比活度为16.80～17.43 Bq/m3,平行样研究结果表明此方法的重现性很好.     

生物组织光传播的理论研究

从光的传输理论出发,利用漫射近似方程,推导出当无限细脉冲光及连续光束垂直入射到生物组织表面时,生物组织表面漫反射光随空间及时间变化的解析表达式。详细分析了组织光学特性参数与组织表面漫反射挑分布之间的关系,为生物组织光学特性参数的无损测量提供了理论根据。