黑河中游现代孢粉传播过程研究

在位于河西走廊的黑河中游地区选取8个河流沉积样品和7个表土样品进行孢粉分析,通过其孢粉百分含量分别探讨河流与风力搬运对孢粉传播的影响。结果表明：风力对孢粉具有较强的搬运能力,能够将区域外或上游山地植被孢粉搬运至中游地区,但其对当地孢粉贡献较小,一般低于10%;河流搬运孢粉的能力大于风力,能够将上游山地植被孢粉大量的搬运至研究区,外来孢粉含量最高可达39.4%,成为孢粉谱的重要成分。表土孢粉组合能够较好的反映研究区现代植被的分布情况;河床沉积物孢粉组合反映的是上游山地植被和研究区植被混合状况。     

The effect of Holocene treeline fluctuations on the sediment chemistry of Lake Kilpisjärvi, Finland

The sediments of Lake Kilpisjärvi were described and analysed for element chemistry and pollen to study the effects of treeline fluctuations in the catchment. Lake Kilpisjärvi is one of the largest lakes in Finnish Lapland, with its catchment partly above the treeline and partly covered with mountain birch woodland. Although the presence of subfossil pine shows that the catchment was previously covered with mountain birch woodland during the Holocene, the present pine treeline has receded 70 km from the lake. Pollen analysis results show that pine immigrated to the area during the Atlantic chrone and that 7000 BP pine forests occupied much of the catchment. Pine started to decline around 3500 BP and vegetation in the catchment became more open. Alkaline and alkaline earth metals and some transition metals document the change from glaciolacustrine clay to more organic sediment. However, these geochemical trends give no indication of changes in erosion rate resulting from changes in catchment vegetation. These changes were detected by plotting suitable element ratios. In addition to the conventional Si/Al and Na/K ratios, the Ca _labile /Si ratio and especially the ratio of labile Ca to K were found to be useful. Of all the elements analysed, potassium showed the strongest reaction to changes in the balance between weathering and erosion. During the phase of denser forests, chemical weathering was dominant, whereas during phases of open catchment, physical erosion prevailed. The effects of changing climate and catchment vegetation were distinguished from other signals. For instance, iron and manganese were enriched at the top of the core due to diffusion and, at the same time, old precipitate layers persisted after burial to deeper levels in the sediment. These iron and manganese rich layers had an effect on the distributions of cobalt, zinc, and vanadium, showing increased concentrations of these elements. Other effects that made the interpretation of chemical records difficult were the effect of ongoing mineralization of organic matter in the top layers of sediment and the effect of biogenic silicon. Owing to the stable conditions of the lake, the desired chemical signals were detected, despite the masking trends.     

Settlement and Stability Analysis on Soft Clay Under Cyclic Loading

The results of undrained cyclic triaxial tests on three types of clays are collected and a relationship among the accumulated strain, the initial stress state, cyclic stress in the soil, as well as the number of cycles is established based on the experimental data. With this relationship, a procedure is proposed for subsidence and stability analysis on soft clay under the action of cyclic loads.     

Optimal Active Control of Wave-Induced Vibration for Offshore Platforms

An obvious motivation of this paper is to examine the effectiveness of the lateral vibration control of a jacket type offshore platform with an AMD control device, in conjunction with H2 control algorithm, which is an optimal frequency domain control method based on minimization of H2 norm of the system transfer function. In this study, the offshore platform is modeled numerically by use of the finite element method, instead of a lumped mass model. This structural model is later simplified to be single-degree-of-freedom (SDOF) system by extracting the first vibration mode of the structure. The corresponding "generalized" wave force is determined based on an analytical approximation of the first mode shape function, the physical wave loading being calculated from the linearized Morison equation. This approach facilitates the filter design for the generalized force. Furthermore, the present paper also intends to make numerical comparison between H2 active control and the corresponding passive control using a T     

南庄头遗址的古植被和古环境演变与人类活动的关系

结合考古、孢粉及硅酸体研究的资料,分析了南庄头遗址的古植被、古气候、古环境的演变与人类活动的关系,研究表明：南庄头人知时期属于早全新世气候升温期,气候不稳定,但总体来说与现代相关差不大,晚期可能比现代更温暖湿润,局部地区出现水蕨,从本剖面的分析来看,没有足够证据证明当时农业已出现。     

中国沿海港口煤炭运输的空间分异格局及演化

煤炭是支撑和保障国家经济发展和社会进步的战略性资源,煤炭运输一直是中国综合运输体系的重要组成部分,而港口是煤炭运输网络中的关键集散中转节点。本文以中国沿海港口为研究对象,以1973-2013年为时间尺度,刻画沿海港口煤炭运输的空间分异格局及演化,重点分析港口煤炭下水与接卸的空间格局演变,归纳总结主要特征和发展规律;然后,采用数理模型和指标,评价港口煤炭下水与接卸的空间集聚水平及变化;最后分析港口煤炭运输的专业化职能及空间分异格局,揭示煤炭下水港和接卸港的空间关系及演变规律。研究发现,中国沿海港口的煤炭运输格局由“南进北出”模式演变为“全进北出”模式,但接卸职能突出的港口仍然集中在长江以南地区,煤炭下水港集中于渤海西岸,而环渤海地区的丹东、大连、烟台、青岛等港口由传统的煤炭下水港演变为接卸港。本研究有助于丰富交通地理和能源地理的理论研究,并为中国沿海港口煤炭运输体系的布局优化提供指导。     

全新世中后期开封西郊黄泛沉积序列的孢粉记录

历史时期以来,黄河在开封市附近多次泛滥形成了相对完整的沉积序列。选取开封市西郊25 m岩芯（ZK_jm）为研究对象,通过孢粉分析,结合地层沉积旋回和历史文献资料,探讨了全新世中后期以来大洪水事件的孢粉记录。结果表明：黄泛地层中的孢粉含量及其组成很好地记录了大洪水事件,洪水沉积期的木本植物花粉含量高于其间断期,而人工禾本科花粉含量低于间断期。每个粒度旋回基本上都有与之对应的孢粉亚带,且其上下界限的吻合度较高,表明孢粉可作为划分沉积旋回的代用指标。岩芯孢粉亚带的数目（12个）多于粒度旋回数目（9个）,孢粉组合特征可以识别出规模较小的洪水或者一次洪水事件出现的多个短期洪水间歇期所形成的沉积,孢粉指标划分沉积旋回的精度高于粒度指标。     

Palynological characteristics of Upper Cretaceous and Paleogene deposits on the west of the Sambian Peninsula (Kaliningrad region), Part 2

The results of studying dinocysts in the Upper Cretaceous-Lower Paleogene succession of the Kaliningrad region are considered. Distinguished in the succession are seven biostratigraphic units in the rank of the Palaeohystrichophora infusorioides, Chatangiella vnigrii, Cerodinium diebelii, Alisocysta margarita, Deflandrea oebisfeldensis, Areosphaeridium diktyoplokum, and Rhombodinium perforatum beds and one Charlesdowniea clathrata angulosa Zone. The Lyubavas Formation has not been distinguished on the west of the Sambian Peninsula. Ages of the Sambia, Alka, and Prussian formations are verified.     

The gravitational effect of ocean tide loading at high latitude coastal stations in Norway

Gravity measurements close to the ocean are strongly affected by ocean tide loading (OTL). The gravitational OTL effect consists of three parts, i.e. a change in gravity caused by direct attraction from the variable water-masses, by displacement of the observing point due to the load, and by redistribution of masses due to crustal deformation. We compare the OTL gravitational effect of several global models to observed time-series of gravity to identify the best model for four arctic observation sites. We also investigate if the global models are sufficient for correcting gravity observations. The NAO99b model fits the observations best at three stations. At two stations (Tromsø and Bodø) the global models explain the variability in the observations well. At the other two (Honningsvåg and Andøya), a significant periodic signal remains after the OTL correction has been applied. We separate two of the gravitational effects, the direct attraction and the change in gravity due to displacement, to study the local effects. Simple geometric models of the water load and independent measurements from local tide-gauges are used to calculate these effects. This leads to improved correspondence with the OTL signal, hence demonstrating the importance of careful modelling of local effects for correction of gravity observations in coastal stations.     

分布式AGS的性能优化研究

ArcGIS Server(AGS)是一个用来构建集中管理、支持多用户的企业级GIS应用平台。由核心的ArcOb-jects构建,是对ESRI其他两个应用服务器ArcSDE和ArcIMS的一个补充。本文运用负载测试和瓶颈检测技术,分析了影响AGS响应时间的因素和运行性能的瓶颈,接着从软件(地图缓存和地图服务)和硬件两个方面提出了具体的优化方案。最后提出了高可用的分布式AGS系统架构。