Least Square Finite Element Method for Viscous Splitting of Unsteady Incompressible Navier–Stokes Equations

In order to solve unsteady incompressible Navier–Stokes(N–S) equations, a new stabilized finite element method,called the viscous-splitting least square FEM, is proposed. In the model, the N–S equations are split into diffusive and convective parts in each time step. The diffusive part is discretized by the backward difference method in time and discretized by the standard Galerkin method in space. The convective part is a first-order nonlinear equation.After the linearization of the nonlinear part by Newton's method, the convective part is also discretized by the backward difference method in time and discretized by least square scheme in space. C~0-type element can be used for interpolation of the velocity and pressure in the present model. Driven cavity flow and flow past a circular cylinder are conducted to validate the present model. Numerical results agree with previous numerical results, and the model has high accuracy and can be used to simulate problems with complex geometry.     

Penetration Depth of Torpedo Anchor in Two-Layered Cohesive Soil Bed by Free Fall

The penetration depth of torpedo anchor in two-layered soil bed was experimentally investigated. A total of 177 experimental data were obtained in laboratory by varying the undrained shear strength of the two-layered soil and the thickness of the top soil layer. The geometric parameters of the anchor and the soil properties (the liquid limit, plastic limit, specific gravity, undrained shear strength, density, and water content) were measured. Based on the energy analysis and present test data, an empirical formula to predict the penetration depth of torpedo anchor in two-layered soil bed was proposed. The proposed formula was extensively validated by laboratory and field data of previous researchers. The results were in good agreement with those obtained for two-layered and single-layered soil bed. Finally, a sensitivity analysis on the parameters in the formula was performed.     

Carbon and nitrogen dynamics of the intertidal seagrass, <Emphasis Type="Italic">Zostera japonica</Emphasis>, on the southern coast of the Korean peninsula

Seagrasses require a large amount of nutrient assimilation to support high levels of production, and thus nutrient limitation for growth often occurs in seagrass habitats. Seagrasses can take up nutrients from both the water column and sediments. However, since seagrasses inhabiting in the intertidal zones are exposed to the air during low tide, the intertidal species may exhibit significantly different carbon (C) and nitrogen (N) dynamics compared to the subtidal species. To examine C and N dynamics of the intertidal seagrass, Zostera japonica, C and N content and stable isotope ratios of above- and below-ground tissues were measured monthly at the three intertidal zones in Koje Bay on the southern coast of Korea. The C and N content and stable isotope (δ¹³C and δ¹⁵N) ratios of seagrass tissues exhibited significant seasonal variations. Both leaf and rhizome C content were not significantly correlated with productivity. Leaf δ¹³C values usually exhibited negative correlations with leaf productivity. These results of tissue C content and δ¹³C values suggest that photosynthesis of Z. japonica in the study site was not limited by inorganic C supply, and sufficient inorganic C was provided from the atmosphere. The tissue N content usually exhibited negative correlations with leaf productivity except at the upper intertidal zone, suggesting that Z. japonica growth was probably limited by N availability during high growing season. In the upper intertidal zone, no correlations between leaf productivity and tissue elemental content and stable isotope ratios were observed due to the severely suppressed growth caused by strong desiccation stress.     

Characteristics of drift pumice from New Caledonia beaches

Siliceous drift pumice was collected from a total of 40 beaches around the main island of New Caledonia, Southwest Pacific, in order to determine its provenance. New Caledonia is enclosed by a barrier reef lagoon whose 2008 designation as a UNESCO World Heritage Site brought attention to the environmental degradation caused by a century of open cast nickel mining. The frequent, voluminous pumice eruptions in the Southwest Pacific provide ample source material that is somewhat durable, highly transportable in water, and easy to collect and analyze. Geochemical and mineralogical analyses were used to identify the source of the pumice in order to map the transport vector across the open ocean and into the lagoon. Drift pumice was sampled during 2008 and 2010. The mineral assemblage of the pumice was consistently calcic plagioclase, clinopyroxene, orthopyroxene, and opaque minerals. All of the pumice was of fairly uniform geochemistry: low in mafic elements, low in alkalis, with LILE enriched compared to HFSE, and negative Eu, Ti, and Zr anomalies. The pumice is predominately dacitic and tholeiitic. This geochemical signature was consistent with published data from the Tonga arc, which is further supported by the mineralogy. With the exception of two samples (which probably came from either the Kermadec arc or Vanuatu) all of the pumice comes from the Tonga arc. The samples from 2008 are consistent with pumice erupted from Metis Shoal in 2006, and the majority of 2010 samples are consistent with pumice erupted from an unnamed volcano (0403-091) that erupted in 2001.     

香港牡蛎(Crassostrea hongkongensis)新型凝集素ChPerlucin的基因克隆与功能研究

C-型凝集素(C-type lectin)是一类能识别并结合多糖的免疫蛋白质超家族, 本文首次克隆了一种新型香港牡蛎C-型凝集素基因——甘露聚糖结合凝集素, 并获得了该基因的全长序列, 命名为ChPerlucin。结果显示, ChPerlucin基因cDNA全长577bp, 包括21bp的5′末端非翻译区(untranslated region, UTR)、73bp的 3′UTR, 以及483bp的开放阅读框(open reading frame, ORF), 编码160个氨基酸, ChPerlucin蛋白理论分子量为18kD, 等电点为5.95。ChPerlucin蛋白含有保守的C-型凝集素样结构域(C-type lectin or carbohydrate-recognition domain, CLECT); 邻接法(Neighbor-Joining, NJ)进化树分析表明, ChPerlucin与其他贝类的Perlucin聚为一支, 说明该基因是软体动物Perlucin家族的新成员。qRT-PCR结果显示, ChPerlucin在香港牡蛎所检测组织和各个胚胎发育时期中均有表达; 病原菌刺激后, ChPerlucin表达量显著升高; 利用毕赤酵母真核成功表达了ChPerlucin重组蛋白, 发现ChPerlucin重组蛋白具有抑菌效果。以上结果表明ChPerlucin在香港牡蛎的先天性免疫过程中发挥了重要的作用。     

海洋沉积地质过程模拟:性质与问题及前景

探讨了海洋沉积地质数值模拟的功能问题.地球科学研究以正演方法(以数值模拟为代表)和反演方法(以地层记录分析为代表)的结合为特征.数值模拟作为一种重要的研究工具,具有获得过程和机理分析结果、形成工作假说、指导现场观测和采样的作用.与此同时,在正反演交融中模型本身也得到了提高和完善.在海洋沉积地质领域,数值模拟在沉积物输运...     

Uptake mechanism of anthropogenic CO<Subscript>2</Subscript> in the Kuroshio Extension region in an ocean general circulation model

The uptake mechanism of anthropogenic CO₂ in the Kuroshio Extension is examined by a Lagrangian approach using a biogeochemical model embedded in an ocean general circulation model. It is found that the uptake of anthropogenic CO₂ is caused mainly by the increase of pCO₂ dependency of seawater on temperature, which is caused by greater dissolved inorganic carbon concentration in the modern state than in the pre-industrial state. In contrast with the view of previous studies, the effect of the vertical entrainment, which brings waters that last contacted the atmosphere with the past lower CO₂ concentration, is comparatively small. Winter uptake of anthropogenic CO₂ increases with the rise of the atmospheric CO₂ level, while summer uptake is relatively stable, resulting in a larger seasonal cycle of the uptake. This increase is significant, especially in the Kuroshio Extension region. It is newly suggested that this increase in the Kuroshio Extension region is largely caused by the combined effects of the increased pCO₂ dependency of the sea water on the temperature and the seasonal difference in cooling.     

Importance of intracellular Fe pools on growth of marine diatoms by using unialgal cultures and on the Oyashio region phytoplankton community during spring

We report on the ability for luxury Fe uptake and the potential for growth utilizing intracellular Fe pools for 4 coastal centric diatom isolates and in situ phytoplankton assemblages, mainly composed of diatoms. Iron uptake of the diatom isolates and natural phytoplankton assemblages in the Oyashio region during spring blooms were prevented by adding hydroxamate siderophore desferrioxamine B (DFB). After the addition of DFB, intracellular Fe in the diatom isolates supported 2.4–4.2 cell divisions with 1.2–2.6 Chl a doublings. The intracellular Fe was primarily used for cell generation rather than Chl a production, leading to a reduction in the Chl a cell quota in the Fe-starved cells with time. The metabolic properties of the Fe-starved cells with their cell morphologies were different among species or genera. An on-deck incubation experiment also exhibited 1.9 cell divisions and 0.81 Chl a doublings of phytoplankton after the addition of DFB, also indicating the preference of cell generation over Chl a production. A decrease in the level of cellular Chl a, a main light-harvesting pigment in Fe-starved diatoms, may become a superior survival strategy to protect the cells from high irradiance that can cause photo-oxidative damages through photosynthesis. Such relatively low-Fe with high-light conditions could often occur in surface waters of the Oyashio region from spring to summer.     

InSAR detection of residual settlement of an ocean reclamation engineering project: a case study of Hong Kong International Airport

Man-made land or islands that are reclaimed from the sea are suitable for building airports, harbors, and industry parks for material transportation because of their broad air and land spaces. However, the reclaimed foundation settlement process is of public concern, including the continuous impact of ocean processes on its stability. The majority of the buildings and facilities of Hong Kong International Airport (HKIA) are built on a reclaimed foundation. The reclaimed foundation has been in residual settlement since completion of the filling project in 1994. In this study, we use persistent scatterer interferometry (PSI) and ENVISAT (European Satellite) advanced synthetic aperture radar (ASAR) data to detect the residual settlement rates from 19 April 2006 to 9 January 2008. We use ground truth data to develop empirical correction models for correcting systematic biases in the ASAR PSI-detected settlement rates. The corrected data follow the Lorentz distribution well, implying that the residual settlement process is dominated by two modes or categories of settlement rates. The first category represents a relatively stable state and the second category represents a continuous settlement state. A ground settlement rate map of HKIA shows that an area of the Passenger Terminal Building and an area of the Southern Runway are two relatively stable areas. There are two major continuous settlement areas. One covers the airport Midfield. Another is along the coastline, implying that attention should be paid to impacts of ocean processes on the stability of airport foundations.