水下拖曳航行器水动力和拖缆姿态仿真分析

水下拖曳航行器是被广泛应用的水下监测平台。为掌握水下拖曳航行器的水动力及其拖揽姿态,文章通过CFD仿真分析计算其零攻角下的阻力系数,并通过多刚体-球铰模型建立其运动数学模型,分析不同航速下拖曳系统的总拉力、拖缆长度和航行器位置等的参数变化。研究结果表明：随着船舶航速的变化,拖曳系统各项参数变化的差别很大;在200 m深度时,6 kn航速相比4 kn航速的总拉力增加73%,而所需的拖缆长度仅增加1%。该数学模型可对不同航速下的水下拖曳系统的总拉力和拖缆姿态等做出预测,为拖曳系统设计提供技术支撑。     

西藏纳当地区永珠组构造变形特征

西藏纳当地区石炭系永珠组主要为浅变质的砂板岩组合,断层和褶皱非常发育的特征。依据岩石和构造特征可以把区内永珠组分成上、中、下三段。永珠组形成于拉张的被动大陆边缘向裂谷转换的次深海环境,并于中晚二叠世至晚三叠世期间经历了三个构造演化阶段。     

河西走廊成矿带区域成矿规律及找矿方向

河西走廊成矿带是分布于祁连地区最北部的Ⅲ级成矿单元(全国统一编号为Ⅲ-20), 目前共有235处矿产地, 形成了石油、煤、凹凸棒石黏土、萤石、石膏、芒硝、石灰岩、天然石英砂、铁、铜、金、钨等40余种矿产。该成矿带以沉积成矿作用为主, 其次为流体、岩浆、变质和表生成矿作用, 可分为11种矿床类型, 主要成矿期为华力西期、加里东期、燕山期和喜马拉雅期。河西走廊成矿带可进一步划分为2个成矿亚带, 分别为玉门—民乐成矿亚带和山丹—中卫—泾源成矿亚带。根据构造空间、成矿时间、成矿作用和矿种等四要素的耦合关系, 河西走廊成矿带厘定了10个矿床成矿系列, 包括4个沉积作用有关矿床成矿系列、3个流体作用有关矿床成矿系列、1个岩浆作用有关矿床成矿系列、1个变质作用有关矿床成矿系列和1个表生作用有关矿床成矿系列。通过细分成矿时段和细化成矿地质作用, 进一步解析出16个矿床成矿亚系列, 并建立了47个矿床式。根据区内地质、矿产、物探、化探和遥感信息, 河西走廊成矿带共圈出5个综合预测区, 为下一步找矿工作指出了方向。     

Phylogenetic analysis of epibacterial communities on the surfaces of four red macroalgae

Macroalgal surfaces are prone to being attached by bacteria. Epibacterial community structures on marine macroalgae are host-specific but temporally and spatially variable. In this study, we investigated the structure of epibacterial communities on the surfaces of four red macroalgae, Gracilaria lemaneiformis, Gloiopeltis furcata, Mazzaella sp. and Porphyra yezoensis, by analyzing the sequences of 16 S r RNA gene libraries. Healthy individuals of all macroalgae species were collected in winter from a farm at Dalian, China. The results showed that the epibacterial communities were mainly dominated by α-Proteobacteria, γ-Proteobacteria and Bacteroidetes. Deinococcus-Thermus, Spirochaetes and ε-Proteobacteria were also found. The majority of cloned sequences shared the greatest similarity to those of culturable organisms. A large portion of sequences from the α-Proteobacteria homed in Roseobacter clade, i.e., genera Ahrensia, Roseovarius, Litoreibacter, Octadecabacter, Thaiassobacter and Sulfitobacter, while members of Bacteroidetes mainly belonged to family Flavobacteriaceae. The cloned sequences could be separated into 66 OTUs at 0.01 distance value, and rare common OTUs were found among libraries. At genus level, Pseudoalteromonas dominated Gr. lemaneiformis and Gl. furcata libraries, accounting for 72.2% and 47.3%, respectively. Sulfitobacter dominated P. yezoensis library, accounting for 35.4%. A previously undefined cluster within Deinococcus-Thermus dominated Mazzaella sp. library, accounting for 24.6% of the all. These results indicated that a broad range of bacteria inhabited the surfaces of these macroalgae.     

坎苏剖面记录的西天山地区黄土磁学性质及其控制因素初探

西天山地区坎苏(KS)黄土剖面的岩石磁学研究结果表明,与黄土高原地区黄土基本一致,磁性矿物以亚铁磁性矿物为主,磁铁矿和磁赤铁矿占据重要地位,针铁矿也普遍存在于地层中.该剖面中磁性矿物的含量高,硬磁性矿物含量也高.磁性矿物磁晶粒度以假单畴和多畴(PSD/MD)为主,而S1S3的磁晶粒度较细,表现为粗单畴(SSD)的性质....     

Harmful algal bloom-forming dinoflagellate Prorocentrum donghaiense inhibits the growth and photosynthesis of seaweed Sargassum fusiformis embryos

Journal of Oceanology and Limnology - Harmful algal bloom (HAB) is an ecological disaster to local mariculture. At present, its impact on macrophytes has not been well studied. In this study, we...     

兰州市区酸雨及其生成机制

通过对１９９２ ～１９９４ 年１７９ 个降水过程的ｐ Ｈ 值分析发现,这３ 年期间兰州市区共出现了２１次酸雨,且酸雨出现次数占降水总次数的１１ ．７ ％ ;兰州市区酸雨主要发生在夏半年;兰州酸雨的形成与市区空气中高 Ｓ Ｏ２ 和 Ｎ Ｏ Ｘ 源密切相关。     

基于虚拟监控技术的机器人系统

介绍了一种虚拟现实技术(VR)与智能机器人监控技术协同作业的机器人系统,该系统使用虚拟现实技术建造具有良好交互性的人机界面,并且结合智能机器人监控技术,实现了虚拟监控操作。通过机器人系统,将虚拟操作结果作为一个整体对象投射到工作现场,完成了实际作业,并以水下机器人检查钻井平台水下部分的焊缝工作为背景,说明了本系统各种功能的实现过程。     

Geochemistry, Geochronology, Sr-Nd Isotopic Compositions of Jiang Tso Ophiolite in the Middle Segment of the Bangong- Nujiang Suture Zone and Their Geological Significance

The Jiang Tso ophiolite,situated in the middle segment of the Bangong- Nujiang Suture Zone,is a part of the easternmost Qieli Lake ophiolite subzone and is close to the south of Pung Lake ophiolite. The rock association of Jiang Tso ophiolite is relatively complete and is mainly composed of metamorphic peridotite,gabbro and diabase. Comparing with N-MORB,the ophiolite is high in Mg and low in Ti,K,Na,P,and is depleted in Nb,Ta,Hf,Th and enriched in Rb,Sr and Ba. Geochemical characteristics of the Jiang Tso ophiolite indicate it is of a supra-subduction zone type formed in the spreading ridge of back arc basin. The SHRIMP U-Pb dating of zircons from the gabbro yielded a weighted average age of 188.1±4.1 Ma(MSWD=1.4),indicating the Jiang Tso ophiolite was formed in the late stage of early Jurassic. The Sr,Nd isotopic compositions show that the Tethyan mantle domain is the depleted mantle(DM),with enriched mantle domain II(EM II). They have the same Sr,Nd isotopic composition with the India Ocean MORB type.     

海空重力测量及应用技术研究进展与展望(一):目的意义与技术体系

作为海空重力测量及应用技术研究进展的开篇,首先简要介绍了该项技术的研究背景,然后详细论述了海空重力测量信息的应用价值及开展该项技术研究的目的意义和应用需求,分析了海空重力测量的技术特点,提出了海空重力测量及应用技术体系的基本架构,明确了该项技术的研究内容、作业流程及各个技术环节的相互关系。