乌鲁木齐地区地磁静日场Sq的变化特征

根据乌鲁木齐地磁台所编的1989年《地磁观测报告》,采用地磁静日场的水平分量(H)和垂直分量(Z)资料,选用其特征量——日变幅和相位,对乌鲁木齐地区地磁静日场S_q的变化特征进行初步统计分析表明,该工作对于进一步认识和研究乌鲁木齐地区地磁静日场的变化规律,为利用地磁预报地震提供背景值资料具有一定意义。     

Historic range of variability in geomorphic processes as a context for restoration: Rocky Mountain National Park,Colorado, USA

Evaluation of historic range of variability (HRV) is an effective tool for determining baseline conditions and providing context to researchers and land managers seeking to understand and enhance ecological function. Incorporating HRV into restoration planning acknowledges the dynamic quality of landscapes by allowing variability and disturbance at reasonable levels and permitting riverine landscapes to adapt to the physical processes of their watersheds. HRV analysis therefore represents a practical (though under‐utilized) method for quantifying process‐based restoration goals. We investigated HRV of aggradational processes in the subalpine Lulu City wetland in Rocky Mountain National Park to understand the impacts of two centuries of altered land use and to guide restoration planning following a human‐caused debris flow in 2003 that deposited up to 1 m of sand and gravel in the wetland. Historic aerial photograph interpretation, ground penetrating radar surveys, and trenching, coring, and radiocarbon dating of valley‐bottom sediments were used to map sediment deposits, quantify aggradation rates, and identify processes (in‐channel and overbank fluvial deposition, direct hillslope input, beaver pond filling, peat accumulation) creating alluvial fill within the wetland. Results indicate (i) the Lulu City wetland has been aggrading for several millennia, (ii) the aggradation rate of the past one to two centuries is approximately six times higher than long‐term pre‐settlement averages, (iii) during geomorphically active periods, short‐term aggradation rates during the pre‐settlement period were probably much higher than the long‐term average rate, and (iv) the processes of aggradation during the last two centuries are the same as historic processes of aggradation. Understanding the HRV of aggradation rates and processes can constrain management and restoration scenarios by quantifying the range of disturbance from which a landscape can recover without active restoration. Copyright © 2011 John Wiley & Sons, Ltd.     

径流驱动土壤分离过程的影响因素及机制研究进展

土壤侵蚀包括土壤分离、泥沙输移和泥沙沉积3个子过程,研究这些过程发生、发展的水力、地形、土壤及地表特性等临界条件及各过程间相互影响、相互制约的机制,是建立土壤侵蚀过程模型继而准确预报土壤侵蚀的基础。为加强对径流驱动土壤分离过程的认识,推动土壤侵蚀过程与机理的研究,从径流水动力学特性、土壤特性、近地表特性、土壤分离过程的时空变异特性等方面对径流驱动的土壤分离过程影响因素及机制进行了总结和梳理,在此基础上,从土壤分离过程研究的时空尺度、土壤分离过程的动力学机制、细沟发育及其形态特征、网络结构对土壤分离过程的影响机制、土壤分离与泥沙输移的耦合机制、土壤分离测定方法与标准、土壤侵蚀阻力参数获取与预报等方面,展望了该领域有待深化的问题及今后的发展方向。     

Bayesian Inference of Spatial Covariance Parameters

This paper shows the application of the Bayesian inference approach in estimating spatial covariance parameters. This methodology is particularly valuable where the number of experimental data is small, as occurs frequently in modeling reservoirs in petroleum engineering or when dealing with hydrodynamic variables in groundwater hydrology. There are two main advantages of Bayesian estimation: firstly that the complete distribution of the parameters is estimated and, from this distribution, it is a straightforward procedure to obtain point estimates, confidence regions, and interval estimates; secondly, all the prior information about the parameters (information available before the data are collected) is included in the inference procedure through their prior distribution. The results obtained from simulation studies are discussed.     

龙门山中段后山断裂带晚第四纪运动特征

本文通过对龙门山断裂带中段后山断裂带主要断裂的研究,认识到从茂汶断裂往西北到挂思岭断裂,断裂最新活动时代有逐渐变老的趋势,反映了龙门山后山断裂在晚新生代同样具有前展式(背驮式)逆冲推覆特征,主断裂茂汶断裂的最新活动时代为晚更新世晚期;后山断裂带除逆冲挤压构造变形外,还存在拉张变形,这为研究青藏高原的运动学及动力学等问题提供了重要信息.     

Structure of gravel beaches and their relationship to tidal range

The height of accretionary gravel beaches, determined by the vertical distance between the large sphere zone at the seaward margin and the large disc zone at the landward margin, is determined mainly by tidal range. As the beach builds seaward, this height translates into thickness and so the complete thickness of gravel beach accumulations is a good indicator, in the geological record, of tidal range. Beaches with a small tidal range have the zone between the large discs and the large spheres compressed and sometimes steepened. These beaches are characterized mainly by cusps and berms, both of which yield steeply dipping, seaward building, cross‐strata. Beaches built by large, persistent waves generally have a steep profile, whereas those with small wave height appear to have a shallow profile. Cusps generally have extremely well‐sorted gravels, often in an openwork fabric and with a landward crown of coarse gravel that may grade seaward into shape‐sorted, gently dipping gravels. Berms, which may extend for hundreds of metres along the coast, comprise, in section, very well‐sorted cross‐stratified gravels that may intermittently build seaward for a distance >15 m. Extensive selection pavements typify beaches with a high tidal range and comprise sheets of gravel which are well‐sorted and dip at comparatively low angles towards the sea. These selection pavements form beds that, in section, can be >50 m in seaward length; they grow from clasts, supplied to them from swash or backwash, and which are selected by the fabric of the existing sheet. In some cases, the selection pavements can be very mature having only a specific clast shape and size remaining. Total preservation of the beach sequence in the geological record is more likely to take place in areas of rapid deposition of sediments, such as the marine fringes to a fan delta.     

多变量时滞回归模型在江南地区初夏降水低频分量延伸期预报中的应用

利用江南地区77个台站的日降水资料及NCEP/NCAR再分析资料,基于不同时间尺度的江南地区降水低频分量和东亚地区850 h Pa低频经向风主成分,建立了多变量时滞回归(Multivariable Lagged Regression,MLR)模型,并对2011年5—7月江南降水低频分量进行延伸期逐日预报试验。结果表明,50~70 d时间尺度的江南低频降水的平均预报技巧高达0.92,可准确预报持续性强降水过程和降水低频位相的正负转换。对利用2001—2012年资料分别构建的MLR模型的历史回报预测试验表明,在50~70 d振荡较强和正常的年份,模型能提前30 d做出初夏江南低频降水分量预报。模型结果也表明,850 h Pa低频经向风的发展和演变是影响初夏江南低频降水未来30 d变化的显著信号,可作为延伸期强降水预报的关键因子。     

土壤侵蚀及其影响因素空间相关性分析

土壤侵蚀是影响区域生态环境的重要因素,它受气候、地形地貌、土壤、植被和人类活动等因素的影响.为寻找流域上土壤侵蚀的主导影响因子,收集了黄河流域气候、地形、植被、土壤等数据,通过引入信息熵原理分析了各个影响因子与土壤侵蚀的空间相关性.结果表明,在黄河流域1:10万地图比例尺条件下.各因子对土壤侵蚀影响的大小排序为:①水蚀区,加权降雨量＞地形起伏度＞植被覆盖度＞土壤类型＞沟壑密度;②风蚀区.地形起伏度＞风蚀气候因子＞植被覆盖度＞土壤类型＞沟壑密度;③冻融区,沟壑密度＞地形起伏度＞气温变化率＞植被覆盖度＞土壤类型.该研究在定性变量和定量变量之间建立了定量的空间相关性分析,研究结果给出了影响黄河流域水力侵蚀、风力侵蚀、冻融侵蚀的主导性因子,可为流域土壤侵蚀过程研究和水土保持决策提供参考.     

基于电导率测定海水悬沙含量试验研究

为了寻求一种简单、快速、连续确定悬浮泥沙含量的方法,以高含沙量海区黄河口泥沙为研究对象,利用电导率仪测定了不同悬浮泥沙含量水体的电导率,建立起了悬浮泥沙含量与电导率之间的关系,并对影响上述关系的因素进行了分析,结果表明,悬浮泥沙含量与电导率之间有很好的线性关系;盐度、颗粒粒径对电导率具有一定的影响,其中盐度的影响最大,颗粒粒径的影响较小。在盐度变化范围有限的高悬沙含量海区,用电导率的方法来实现现场监测悬浮泥沙含量是可行的。     

柳州市汽车制造业企业的空间格局与影响因素

中国是世界汽车生产大国,产销量已连续9年蝉联世界第一,然而有关汽车产业的研究更多集中在区域尺度,对城市尺度的研究相对较少。本文以柳州市为案例,利用工商注册企业数据和核密度估计、负二项回归模型等方法分析了柳州市汽车制造业企业的空间格局与影响因素。结果表明：① 汽车制造业企业主要集中在河西、洛维、河东、阳和等城市组团,企业集聚范围逐步向东、向西扩散,其中向东扩散以柳东新区为主,向西扩散以河西高新技术产业开发区为主;② 汽车制造业企业在距离市中心0~11 km显著集聚,空间集聚强度呈现先增加后减小的趋势;③ 土地价格、交通条件、地方化经济、政策是影响汽车制造业企业区位选择和空间格局的重要因素;同时,汽车制造业JIT（Justin Time）生产方式也具有重要影响。在此基础上,提出汽车制造业企业区位选择和空间格局形成的循环累积机制、区位临近机制、价格传导机制。