Electrons in feldspar II: a consideration of the influence of conduction band-tail states on luminescence processes

 Most natural feldspars contain many charged impurities, and display a range of bond angles, distributed about the ideal. These effects can lead to complications in the structure of the conduction band, giving rise to a tail of energy states (below the high-mobility conduction band) through which electrons can travel, but with reduced mobility: transport through these states is expected to be thermally activated. The purpose of this article is twofold. Firstly, we consider what kind of lattice perturbations could give rise to both localized and extended conduction band-tail states. Secondly, we consider what influence the band tails have on the luminescence properties of feldspar, where electrons travel through the sample prior to recombination. The work highlights the dominant role that 0.04–0.05-eV phonons play in both the luminescence excitation and emission processes of these materials. It also has relevance in the dating of feldspar sediments at elevated temperatures. Received: 11 May 2001 / Accepted: 6 September 2001     

导管架式海洋平台结构阻尼隔振体系及其减振效果分析

导管架式海洋平台结构是当前应用最广的一种平台结构形式。本文研究导管架式海洋平台结构阻尼隔振体系及其减振效果。针对导管架式海洋平台结构的型式与特点，为了充分发挥阻尼器的耗能减振作用，提出了在平台结构导管架端帽和甲板之间设置柔性阻尼层的新型阻尼隔振方案。针对渤海JZ20－2MUQ平台结构，建立了海洋平台结构阻尼隔振体系简化计算模型，研究了隔振层参数与结构阻尼比的关系以及它们对结构整体和隔振层层间相对位移的控制效果；进行了多种冰荷载工况和地震工况的数值模拟。结果表明，阻尼隔振方案是导管架式海洋平台结构的一种有效的减振措施。     

海洋平台结构振动的AMD主动控制参数优化分析

本文针对海洋平台结构的冰激振动和地震反应控制问题，提出了采用AMD主动控制的控制策略，结合JZ20－2MUQ平台结构进行了AMD控制系统的硬参数和软参数的优化分析，并就相应于最优参数下的AMD控制海洋平台结构冰激振动和地震反应的几种代表性工况进行了时程分析，得到了一些定性和定量的结论，为实际工程的控制设计提供了基础。本文提出的AMD主动控制方法对类似的海洋平台结构的控制问题也有参考价值。     

极地冰雪氢氧同位素指标及其指示意义

本文综述了水汽来源状况、降水季节变化、火山喷发、太阳活动等气候环境因素对极地冰雪中同位素含量的可能影响及其程度 ,以及降水区域不均衡性、降水年际不均衡性、逆温层和同位素在冰雪中的扩散迁移作用等几种不稳定因素可能对冰雪同位素分析造成的干扰 ;在此基础上 ,综述了极地冰雪中δ1 8O、δD和其差值d(d =δD - 8δ1 8O)与局部或全球气温之间的一些线性关系 (包括全球尺度 ,格陵兰地区 ,南极地区等 )及它们在空间分布上的变化规律     

Gelifluction within a solifluction lobe in the Kärkevagge valley, Swedish Lapland

Soil displacement, soil temperature, depths of thaw plane and groundwater level were continuously monitored during the period from July 1999 to June 2000 within a solifluction lobe in the Kärkevagge valley, northern Sweden. The strain–probe method was used to measure soil displacement, and we found significant soil displacements in the thawing period 2000. These displacements were the result of gelifluction. The ice content profile showed that gelifluction occurred at the same time as the thaw plane reached the layers with high ice content at shallow soil depths (0–6 and 16–25 cm deep). In contrast, gelifluction did not occur when the thaw plane reached the layers with high ice content at greater depth (46–49 cm deep). These observations indicate that thawing of ice lenses in the near–surface layer triggers gelifluction.     

Detailed geomorphological survey of a small mountain drainage area, Abisko, northern Swedish Lapland

A thorough geomorphological survey of a small (2km²) drainage area has been conducted using digital magnification of aerial photographs in conjunction with field visits. The result presented is a geomorphological map where individual geomorphological features down to metre size can be identified. The study was done in connection with a project focusing on the relationship between geomorphological processes and lacustrine sedimentation. Good knowledge of the geomorphological setting and the related process activity in the catchment is important in studies using lacustrine sediments as environmental archives.
The survey reveals a small–scale geomorphology dominated by a number of different periglacial upfreezing forms together with bedrock–controlled slope processes. Three different geographically separated geomorphological assemblages were recognised with few sediment transportation pathways connecting them. Composition of substrate, soil water content and vegetation cover combined with different slope angles are probably the most important factors controlling the distribution of the geomorphological features.     

生态交界带特征与动态变化机理分析

文章论述了生态交界带是两个以上生态系统交接的过渡带，它具有特有的生态系统结构，生态交界带生态系统的结构，功能和物质，能是以及信息的交流与相邻生态系统有密切的联系，但又表现出明显的异质性，其动态变化机理显示生态交界带内物质，能量和信息的均衡状况。     

青藏公路铁路沿线生态系统特征及道路修建对其影响

根据2001—08和2002—08月野外调查数据及2001年1：100万中国植被图、1996年1：400万青藏高原植被区划图和2000年青藏铁路沿线自然保护区分布及功能区界调整图，以青藏公路铁路沿线植被生态系统为研究对象，运用ARCVIEW和ARC／INFO软件研究青藏公路铁路建设对沿线生态系统结构的影响，结论如下：①青藏公路铁路南北跨越9个纬度，东西跨越12个经度，共穿越青东祁连山地草原地带、柴达木山地荒漠地带、青南高寒草甸草原地带、羌塘高寒草原地带、果洛那曲高寒灌丛草甸地带和藏南山地灌丛草原地带6个自然区，对植被类型的统计结果显示了地带性。②青藏公路铁路的建设对生态系统产生直接的切割，使景观更加破碎。③青藏公路铁路的建设直接破坏沿线植被生态系统(主要为50m缓冲区内)，年损失总净初级生产量为30504．62t，损失总生物量432919．25～1436104．3t／a。损失总净初级生产量占1km缓冲区年净初级生产量535005．07～535740．11t／a的百分比为5．70％，占10km缓冲区年净初级生产量3408950．45～3810480．92t／a的0．80～0．89％；损失生物量占1km缓冲区生物总量7502971．85～25488342．71t／a的5．70％，占10km缓冲区总生物量43615065．35～164150665．37t／a的0．80％～0．89％。     

南极无冰区典型沉积环境石英砂表面结构特征及其在沉积环境识别中的应用

本文利用电镜扫描方法 (SEM)对比分析了南极乔治王岛无冰区海滩沉积、冰碛物以及阿德雷岛湖泊沉积等典型沉积环境中的石英砂表面结构特征 ,得出了乔治王岛各典型沉积环境中石英砂表面结构特征的颗粒频率曲线。结果表明 :不同沉积环境下的石英砂颗粒表面结构特征具有相似性 ,这主要和南极地区广泛发育的冰川作用有关 ,同时 ,它们也有各自典型的特征组合 ,这些典型特征组合的不同反映了石英砂后期的搬运历史和沉积环境的差异。本文还依据石英砂表面特征的颗粒出现频率 ,利用聚类分析方法对研究区内三级海岸阶地上的沉积物和一个未知成因的样品进行了沉积环境的判别分析 ,结果证明石英砂微形貌特征可以作为南极地区沉积环境识别的有效手段     

天山1号冰川厚度和冰下地形探测与冰储量分析

通过对天山乌鲁木齐河源 1号冰川的雷达回波探测 ,清晰地揭示出冰川底部冰 /岩界面的位置及其起伏变化特征 ,显示出雷达波对山地冰川良好的穿透能力和对冰下地形的高分辨能力 ,冰川雷达测厚的误差小于 1 .2 %。研究结果显示 ,1号冰川东支冰川平均厚度为 5 8.77m ,西支冰川平均厚度为 44.84m ,冰体厚度最大值发育于冰川中部趋于主流线位置。冰川冰储量计算表明 ,东支冰储量为 0 .0 5 1 868km3,西支冰储量为 0 .0 2 0 2 1 0km3。表面和底部地形有明显差异 ,主要因冰川动力过程对基岩强烈的地貌作用所致 ,意味着冰床的起伏地形对冰川浅层冰体的运动过程影响不显著。