Hydrodynamic interactions and relative motions of two floating platforms with mooring lines in side-by-side offloading operation

The hydrodynamic interaction and mechanical coupling effects of two floating platforms connected by elastic lines are investigated by using a time-domain multi-hull/mooring/riser coupled dynamics analysis program. Particular attention is paid to the contribution of off-diagonal hydrodynamic interaction terms on the relative motions during side-by-side offloading operation. In this regard, the exact method (CMM: combined matrix method) including all the vessel and line dynamics, and the 12×12 hydrodynamic coefficients in a combined matrix is developed. The performance of two typical approximation methods (NHI/No Hydrodynamic Interaction: iteration method between two vessels without considering hydrodynamic interaction effects; SMM/Separated Matrix Method: iteration method between two vessels with partially considering hydrodynamic interaction effects, i.e. ignoring off-diagonal cross-coupling terms in the 12×12 hydrodynamic coefficient matrix) is also tested for the same side-by-side offloading operation in two different environmental conditions. The numerical examples show that there exists significant discrepancy at sway and roll modes between the exact and the approximation methods, which means that the cross-coupling (off-diagonal block) terms of the full hydrodynamic coefficient matrix play an important role in the case of side-by-side offloading operation. Therefore, such approximation methods should be used with care. The fender reaction forces, which exhibit large force with contact but no force without contact, are also numerically modeled in the present time-domain simulation study.     

Chemical and Biological Studies of Particulate Organic Matter in the Ocean

This paper presents a review of the past decade's highlights of research on the isolation and characterisation of particulate organic matter (POM) in the world's oceans. The emphasis is on chemical studies but, in keeping with the growing interdisciplinary nature of marine science, advances in other disciplines are also discussed, particularly those in biological sciences. Increasing evidence for the importance of picoplankton, bacteria and viruses as POM constituents is highlighted, including the recent recognition of large populations of autotrophic bacteria able to harvest light for energy. The transport of POM to bottom waters was thought to be largely confined to large, rapidly sinking faecal pellets. However, recent studies have highlighted the importance of organic aggregates and flocs formed by diatoms such as Rhizosolenia and other microalgae. Ascending particles have also been discovered, many of which are lipid-rich. Several studies have shown that resuspension of bottom sediments and lateral advection of material from continental shelves can lead to anomalously high particle fluxes measured in sediment traps moored in deep water. Many new approaches for characterizing POM have emerged, such as pyrolysis gas chromatography-mass spectrometry and direct temperature-resolved mass spectrometry for analysis of higher molecular weight materials and biopolymers. Lipid biomarker techniques have also advanced, exciting new possibilities being raised by the ability to measure stable and radioactive carbon isotopes for individual compounds. The techniques of molecular biology, such as the polymerase chain reaction (PCR), are being increasingly applied to provide complementary information to more conventional microscopy and flow cytometry on the identity of organisms in the sea. The combination of these techniques with advanced chemical analysis methods promises to greatly increase our knowledge of the origins, transport and fate of organic matter in the oceans. This revised version was published online in August 2006 with corrections to the Cover Date.     

Determination of heterogeneous reaction probability using deposition profile measurement in an annular reactor: Application to the N2O5/H2O reaction

A method for the estimation of the reaction probability of the heterogeneous N₂O₅+H₂O 2HNO₃ reaction using the deposition profile in a laminar flow tube, in which the walls are coated with the condensed aqueous phase of interest, is presented. The production of gas phase nitric acid on the surface followed by its absorption complicates the deposition profiles and hence the calculation of the reaction probability. An estimation of the branching ratio for this process enables a more appropriate calculation to be carried out. Reaction probabilities of N₂O₅ on substances including some normally constituting atmospheric aerosols, NaCl, NH₄HSO₄, as well as Na₂CO₃ are estimated and found to depend on relative humidity and characteristics of the coating used. These fell within the range (0.04–2.0)×10^–2.     

氟化物对紫露草(Tradescantia paludosa)的诱变作用

用紫露草微核技术,检测几种氟化物的微核(MCN)效应。指出氟化物有损伤染色体的作用,环境中的氟污染既引起一般公认的牙釉病和氟骨病,还有损伤染色体的遗传毒性。     

青海尕林格铁矿床电气石矿物学、元素地球化学及成因研究

尕林格矽卡岩型铁多金属矿床位于青海东昆仑祁漫塔格造山带与柴达木盆地结合带中部。电气石作为矿区内普遍出现的矿物,部分呈半自形-自形粒状出现在正接触带矽卡岩化蚀变火山岩中(Tour-Ⅰ),也有呈他形粒状形式出现在外接触带变质砂岩中(Tour-Ⅱ)。因其生长化学行为与寄主岩石和流体的化学属性强烈相关,所以电气石的主、微量元素成分为研究热液体系背景下的流体演化及成矿物质来源提供了渠道。尕林格电气石的化学成分包括富Na-Mg的镁电气石和富Ca-Mg的钙镁电气石。Tour-Ⅰ中的环带电气石存在早期核部(Gen-1)被晚期边部(Gen-2)交代的不连续反应边特征。Gen-1为钙镁电气石,而Gen-2为镁电气石。由于镁铁质火山岩的缓冲作用,Gen-1更多地显示出原地寄主岩石的化学成分。随着流体的持续补充,Gen-2则更多地与流体成分保持平衡,显示出较窄的变化范围,与成矿密切相关。Gen-1比Gen-2更加富Fe,意味着流体中Fe浓度降低;而Na含量逐渐上升则暗示流体p H值的升高。尕林格绝大部分矽卡岩电气石都是在早期成核阶段结晶生长的,因为电气石在酸性和中酸性溶液中更加稳定。除此之外,部分Tour-I中还存在沿早期电气石颗粒边缘生长的增生边结构(Gen-3)。Gen-3比Gen-1更加富Ca,推测Gen-3是在相对封闭环境下颗粒间隙溶液作用下的产物。Tour-Ⅱ则既包括钙镁电气石,又含有镁电气石。在Tour-Ⅰ中,Fe和Mg的含量变化范围较大,这与实际观测的Tour-Ⅰ围岩为镁铁质中-基性火山岩密不可分。Tour-Ⅱ比Tour-Ⅰ更加富集B、Ti、Sc、V、Cr、Ga、LREE等元素,这与B的溶解度随流体p H值的升高而升高有关。随着岩浆演化流体p H值的升高,B在相对碱性溶液中大量富集,而大部分微量元素和LREE易与挥发分结合成络合物的形式迁移,因此,B含量高的溶液中部分微量元素和稀土元素含量也会升高。     

Calculated phase equilibria involving chemical potentials to investigate the textural evolution of metamorphic rocks

Evolving pressure–temperature conditions during metamorphism drive changes in the stable mineral assemblage, mineral proportions and mineral compositions in rocks. These changes are achieved via the diffusion of components between minerals, fluid and melt, the driving force for diffusion being the gradients in chemical potential of the components developed spatially within the rock. This study utilises recent developments in the software thermocalc to investigate quantitatively chemical potential relationships in rocks, with the phases involved being (solid) solutions. Phase diagrams with chemical potentials as axes are used to understand better the spatial rearrangement of components during the metamorphic evolution of rocks and the metamorphic textures that result. In contrast to qualitative chemical potential diagrams, quantitative diagrams can be contoured for mineral composition, allowing consideration of chemical zoning in minerals. Furthermore, the amount of material required to diffuse to equalise chemical potentials can be calculated. We start by demonstrating the approach via an example of retrograde corona development in an ultra-high-temperature granulite. Whereas the use of chemical potentials to consider the retrograde development of corona textures is well known, they are also significant in considering the prograde history. The role of chemical potentials in prograde metamorphic textural evolution is highlighted in consideration of the consumption and growth of aluminosilicates during the kyanite-to-sillimanite reaction, and the growth of garnet porphyroblasts.     

法门寺合十舍利塔主体塔钻孔灌注桩桩身质量控制

法门寺合十舍利塔主体塔桩基工程,设计工程寿命100年,工程质量要求严格,通过施工中砼碱骨料反应控制以及成孔质量、孔底沉渣、砼灌注、后压浆等环节的质量控制,工程质量满足要求。     

天津市深层淡水井的水质咸化分类——以东丽区为例

第四系第Ⅱ含水组地下水经长期开采,早已完成主固结过程;开采Ⅱ组地下水可使上覆咸水淡化越流,最终加快各类地表水的入渗,多年来在适宜地段大幅恢复Ⅱ组地下水的开采。经调查大部分水井水质恶化非含水层水质变化,绝大多数地区咸水底界没有下移趋势。笔者认为在滨海平原区能使咸、淡水保持数10万年高浓度差的粘土层,具有半透膜特性。由于部分观点与前人研究结果相左,澄清"井水咸化"与地下水咸化污染的区分就显得尤为重要。为此,将多年地下水水质调查资料进行分类,推进咸化污染机理研究推进。