基于分层EOF的深海声速剖面时变特征建模

针对目前局部海域小时间尺度声速场建模方法未顾及不同深度区间内声速变化规律的问题,本文根据实测深海声速剖面的统计特征,提出了声速剖面分层方法,并进一步基于经验正交函数（Empirical Orthogonal Function, EOF）提出了局部小时间尺度的声速剖面分层时变模型构建方法。利用南海实测全海深声速剖面数据,分析了分层EOF第一模态系数和等效平均声速的日变化特征,并比较了不同拟合模型的精度。最后,利用试验海区的温度和潮汐数据分析了声速剖面周期变化的影响因素。结果表明： ①声速剖面分层EOF第一模态系数及等效平均声速具有日周期变化特征,上层声速日周期变化特征不明显,中层声速日周期变化特征较明显,下层声速变化较小但仍具有日周期变化特征;②局部海域小时间尺度声速拟合应考虑长期变化项的影响;③试验海区声速剖面EOF第一模态系数变化与温度显著相关,提取的声速剖面时变特征与海区潮汐周期特征基本吻合。     

赣北芙蓉―周溪断面下蜀黄土粒度特征及其指示意义

赣北鄱阳湖地区沙山南部近南北向的芙蓉―周溪断面上,分布由FZ-01、FZ-02~FZ-05和FZ-06~FZ-12三部分组成的下蜀土剖面,粒度分析结果表明:1)下蜀黄土砂粒组分自北往南变化为27.29%、1.94%~7.23%和0.45%~7.27%;粉砂组分质量分数大,且存在差异变化,分别为68.23%、81.71%~87.20%和66.9%~79.39%;黏土组分自北向南质量分数增加,变化为4.48%、8.46%~16.35%和18.13%~32.07%,总体表现为砂黄土―黄土―黏黄土等相态的逐渐过渡;2)粒度三组分、粒度参数散点图等均表现为从北而南的阶段性系统渐变特征;3)各种粒度参数与距长江的远近,均服从对数函数变化关系。这些特征初步揭示研究区的下蜀黄土是风成的,并可能与同样是风成堆积的沙山的形成存在某种联系,属于区域性风沙-风尘堆积体系。     

Enriching user profiles using geo-social place semantics in geo-folksonomies

Geo-folksonomies link social web users to geographic places through the tags users choose to label the places with. These tags can be a valuable source of information about the user’s perception of place and can reflect their experiences and activities in the places they label. By analysing the associations between users, places and tags, an understanding of a place and its relationships with other places can be drawn. This place characterisation is unique, dynamic and reflects the perception of a particular user community that generated the geo-folksonomy. In this work, an approach is proposed to analysing geo-folksonomies that builds on and extends existing statistical methods by considering specific concepts of relevance to geographic place resources, namely, place types and place-related activities, and by building a place ontology to encode those concepts and relationships. The folksonomy analysis and evaluation are demonstrated using a realistic geo-folksonomy data set. The resulting ontology is used to build user profiles from the folksonomy. The derived profiles reflect the association between users and the specific places they tag as well as other places with relevant associated place type and activities. The methods proposed here provide the potential for many interesting and useful applications, including the harvesting of useful insight on geographic space and employing the derived user profiles to enhance the search experience and to identify similarities between users based on their association to geographic places.     

The application and comparison of several flux profile relations in CoLM

This paper discusses the important role that flux profile relations play in momentum flux, sensible heat flux, and latent heat flux simulations in CoLM （Common Land Model） and compares the application of three flux profile relation schemes in CoLM by means of the Loess Plateau Land-Atmosphere Interaction Pilot Experiment （LOPEX） of 2005. It reveals that the results simulated by the model barely changed in the original flux profile schemes of the models a~er eliminating the very stable condition and the very unstable condition, and there were only tiny changes in numerical values. This indicates that the corrected terms added to fm（ξm）,fh（ξh） were very tiny and can be ignored under very stable and very unstable circumstances. According to a comparison of the three flux profile relations, the simulation results were basically coherent by using any CoLM： the correlation coefficient of the simulation value and the observed value was 0.89, and this bears on the coherence with the numerical procedures for the flux pro- file relations under unstable circumstances. The simulation results were improved considerably by utilizing the Lobocki flux pro- file schemes, which numerical procedures under unstable circumstances differed significantly fi＇om other three flux profile schemes; in this case the correlation coefficient of the value of simulation and the observed value became 0.95. In the next itera- tion of this study, it will be of great importance for the development of the land surface process model to continue experimenting with the application of some novel flux profile schemes in the land surface process models in typical regions.     

深海主跃层环境对会聚区影响的数值分析

应用BELLHOP模式,对声速剖面的声跃层结构变化引起会聚区偏移特征进行了分析。结果表明,声速垂直结构的变化可导致会聚区位置出现不同程度的偏移:跃层强度增加0.01 s-1将使会聚区向远离声源方向偏移1.5~2.0km;跃层厚度增大50m将使会聚区向靠近声源方向偏移0.3~0.5km;跃层位置加深100m将使会聚区向远离声源方向偏移0.5~1.0km。在跃层的三个特征量中,跃层强度起主导作用。跃层强度变化引起的声线在海洋次表层的偏折差异,进而导致进入深海等温层的入射角差异,是使会聚区发生偏移的决定性因素。     

声波探测技术在海底输油管道检测中的应用

介绍了多波束测深系统、侧扫声纳和浅地层剖面等声波探测技术的基本原理及在海底管道检测中常用设备与参数选择。结合工程实例给出了各种检测方法在海底输油管道检测中应用效果。介绍了海底管道检测流程,分析了各种检测方法的优缺点和不足之处。结果表明,海底管道检测时应充分利用各种方法的互补性,提高检测效率和准确性。     

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Performance Evaluation of a Self-Developed Ozonesonde and Its Application in an Intensive Observational Campaign

To make a detailed test on the reliability and detection performance of the electrochemical concentra- tion cell （ECC） type ozonesonde which had been devel- oped and preliminarily evaluated by the authors, an inten- sive ozonesonde release experiment was held at two sites in Beijing and Changchun in June 2013. The results showed that the mean background current and its standard deviation were 0.03 （0.04） pA and 0.02 （0.03） pA in Bei- jing （Changchun）. The average response time and its standard deviation were 27.8 s （30.4 s） and 4.0 s （3.7 s） in Beijing （Changchun）. The ozone partial pressure profiles at both sites showed a central peak in the stratosphere and a side peak in the boundary layer. Large variation in ozone partial pressure was observed at the middle levels of the atmosphere （10-17 kin）. A more marked gradient of ozone change was observed in Beijing （3.4 mPa km-1） at the lower atmosphere level, as compared to that in Changchun （0.4 mPa km-l）. The results presented in this paper indicate that this self-developed ozonesonde shows a high level of reliability and good performance. The ozonsonde is expected to play an important role in opera- tional observations of ozone profiles.     

黔北下志留统龙马溪组烃源岩有机地球化学特征及其古环境意义

通过对黔北地区下志留统龙马溪组烃源岩的有机碳、类异戊间二烯烃、萜烷及甾烷等有机地球化学的研究,发现具有以下特征:①正构烷烃分布以单峰分布为主,主峰碳为nC18~nC20;②Pr/Ph比值在0.16~1.24之间,普遍具有植烷优势;③伽马蜡烷指数0.10;④Ts/(Tm+Ts)比值较高,在0.42~0.61之间,且分布十分稳定;⑤C27/C29甾烷比值在0.65~1.53之间,多数样品具C29甾烷分布优势;⑥有机碳含量普遍大于0.5%,且自下向上呈规律性递减;⑦δ13Corg-28‰,普遍偏轻。这些特征均指示研究区龙马溪组的有机物产率较高,同时具有良好的有机质保存环境。通过对比岩性及有机地球化学剖面,将龙马溪组烃源岩划分为3个发育阶段。     

Slip line theory applied to a retaining wall–unsaturated soil interaction problem

An extension of slip line theory to unsaturated soils is presented and applied to the problem of a rigid retaining wall rotating about its toe into unsaturated soils. Suction is introduced using the effective stress concept. Soil–wall interface friction is defined carefully. The influence of suction on limiting passive earth pressures is analysed for two soils under steady state evaporation and infiltration. Suction increases the limiting passive stress at the soil–wall interface, with a dependence on the steady state flow type. The displacement of the retained soil is studied assuming the wall undergoes a rotation increment. The results show a clear difference in the displacement for evaporation and infiltration.