Biogenic silica cycle in surface sediments of the Greenland Sea

In contrast to several investigations of biogenic silica (BSi) content and recycling in surface sediments of the Southern Ocean, little is known about the benthic cycle of BSi in high northern latitudes. Therefore, we investigated the silicic acid concentration of pore water and BSi content of surface sediments from the Greenland Sea. Low BSi contents of less than 2% were observed. High-resolution (2–5 mm) BSi profiles and comparisons to trap studies suggest that only relatively dissolution-resistant siliceous components reach the seafloor. Pore water investigations reveal BSi fluxes of more than 300 mmol m⁻² a⁻¹ only for a few sites on the shelf. A statistically significant relationship between water depth and BSi rain rate reaching the seafloor was not observed. Sampling along a transect perpendicular to the marginal ice zone (MIZ) revealed no enhanced rain rate of BSi reaching the seafloor in the vicinity of the ice edge. Although the MIZ of the Greenland Sea is characterized by the enhanced export of biogenic particles from surface waters, this feature is not reflected in the benthic cycle of biogenic silica. The lack of such a relationship, which is in contrast to observations of shelf and continental margin sediments in the southern South Atlantic, is probably caused by the enhanced dissolution of BSi in the water column and highly dynamic ice conditions in the Greenland Sea.     

水面舰艇空调通风系统技术现状及展望

通过对国内外水面舰艇空调通风系统设计技术现状的分析比较,提出了国内水面舰艇空调通风系统设计优化解决途径、优化设计目标和发展展望。     

路用多孔页岩陶粒表面修饰优化

为提高路用多孔页岩陶粒的路用性能并提升其阻热性能，优选3种有机处理剂，借助吸水率、筒压强度、控制筛孔通过率及磨耗值试验，确定了不同处理剂最佳修饰工艺；基于吸油率、表面孔隙封堵率与SEM试验，系统研究了修饰前后页岩陶粒表面孔隙封堵情况，对比评价了不同处理剂对页岩陶粒路用性能的影响规律，确定了页岩陶粒最佳处理剂；并在此基础上，全面评价了表面修饰对页岩陶粒混合料路用性能的影响。结果表明：苯基硅树脂的适宜浓度为25%，固化温度为160℃，硅丙乳液的适宜浓度为35%，成膜温度为30℃，助剂含量为3%，建筑防水剂修饰页岩陶粒的适宜浓度为35%，固化温度为85℃；其中苯基硅树脂对页岩陶粒表面封装效果最好，24 h吸油率最低，表面孔隙封堵率高达78%，且SEM图像也表明经表面修饰的页岩陶粒表面开口孔隙数量明显减少；3种处理剂均能不同程度地提高路用多孔页岩陶粒的路用性能，24 h吸水率的降幅在80.48%~94.5%之间，压碎值降幅在4.62%~17.52%之间，磨耗值降幅在5.33%~30.92%之间，黏附性等级提高0.5~2级；苯基硅树脂对页岩陶粒吸水率与黏附性等级改善效果最佳，硅丙乳液对压碎值与磨耗值改善效果最为明显，综合考虑所有评价指标，确定了页岩陶粒最佳处理剂为苯基硅树脂；且经苯基硅树脂表面修饰后的页岩陶粒混合料各项路用性能均有不同程度提高。     

码头面层混凝土表面缺陷防治

论述码头混凝土面层施工常见质量通病对工程使用和观感质量的影响,分析质量通病的成因,提出预防及治理措施。在营口港鲅鱼圈港区四期54#～56#泊位码头面层混凝土施工中,收到了较满意的效果。     

考虑气动阻力和横风稳定的汽车车身多目标优化设计

综合考虑了气动阻力特性和横风稳定性,对车身外形参数进行了多目标自动优化设计。综合利用参数化建模技术、计算流体力学(CFD)仿真、试验设计方法、响应面模型和智能优化算法,集成Pro/Engineer参数化建模和ICEM网格划分工具以及Fluent仿真软件,在多学科优化平台modeFRONTIER上,搭建了一种自动优化设计流程。利用该流程,基于遗传算法(GA)对MIRA快背式模型车身几何外形进行了改型设计,得到了考虑车身气动阻力特性和横风稳定性的最优权衡设计解集。该结果使得气动阻力因数降低了5.2%,侧向力因数降低了5.8%。因而,实现了车身气动阻力和横风稳定性的多目标优化。     

Northern Adriatic Sea surface circulation and temperature/pigment fields in September and October 1997

Satellite images of surface chlorophyll-a concentration measured by the sea-viewing wide field-of-view sensor (SeaWiFS) and of sea surface temperature derived from advanced very high resolution radiometer (AVHRR) measurements, combined with in-situ drifter measurements of surface currents, and ancillary wind, Po River discharge and surface salinity data, are used to describe the surface dynamics in the northern Adriatic during the period September–October 1997.The satellite observations revealed very complex mesoscale dynamics, with time scales of a day or two and length scales of about 10 km, including the meandering and instability of basin-scale currents (e.g., the western coastal layer), jets/filaments and eddies. In addition, the two typical patterns of the Po River plume are observed and qualitatively explained in terms of wind forcing. A basin-wide double gyre pattern spreads the rich runoff water across most of the northern Adriatic from mid-September to early October, following Bora wind events and under stratified sea conditions. In contrast, in late October the Po plume is confined to the coast due to weaker winds and de-stratified conditions. This variability in the Po River plume extension is also confirmed by in-situ salinity measurements.     

结构可靠度分析的智能计算法

模糊数学、神经网络、遗传算法并称为智能计算方法.对功能函数没有明确表达式的问题进行可靠度分析,本文提出了基于响应面重构的智能计算法,即构造一个模糊神经网络响应面并采用遗传算法进行可靠度计算.算例分析表明,该方法与传统的二次多项式响应面方法相比,计算精度较好,可大大减少有限元分析次数.该方法用于大型复杂海洋工程结构的可靠度分析,可相应提高工作效率和解题质量,具有实际应用价值.     

聚丙烯高性能纤维混凝土在码头面层中的应用

介绍聚丙烯高性能纤维混凝土的配合比设计、施工、技术性能及应用情况。     

Prediction of Hydrodynamic Performance of Marine Propellers by Surface Panel Method

The potential based low order surface panel method is used to predict the hydrodynamic performance of marine propellers. In present method the hyperboloidal quadrilateral panels are employed to avoid the gap between the panels. The influencecoefficients of panels are calculated by Morino's analytical formulations for increasing numerically calculating speed.The pres-sure Kutta condition is satisfied on the trailing edge of propeller blade by Newton-Raphson iterative procedure.Therefore the     

基于回转密封表面微观构造缺陷所导致的功能失效及其监控

回转轴密封面的微观构造缺陷会引起动力总成类产品内腔的工作介质外泄,从而因功能失效造成严重的质量问题。从回转密封表面微观结构的形貌特征出发,对工作介质外泄成因做了说明,描述了利用表面轮廓仪、悬线法及白光测量等3种检测方案用于评定回转密封面螺线状态的测量方法。