近50年来淮河流域极端降水的时空变化及统计特征(英文)

Based on the daily precipitation data of 27 meteorological stations from 1960 to 2009 in the Huaihe River Basin, spatio-temporal trend and statistical distribution of extreme precipitation events in this area are analyzed. Annual maximum series (AM) and peak over threshold series (POT) are selected to simulate the probability distribution of extreme precipitation. The results show that positive trend of annual maximum precipitation is detected at most of used stations, only a small number of stations are found to depict a negative trend during the past five decades, and none of the positive or negative trend is significant. The maximum precipitation event almost occurred in the flooding period during the 1960s and 1970s. By the L-moments method, the parameters of three extreme distributions, i.e., Generalized extreme value distribution (GEV), Generalized Pareto distribution (GP) and Gamma distribution are estimated. From the results of goodness of fit test and Kolmogorov-Smirnov (K-S) test, AM series can be better fitted by GEV model and POT series can be better fitted by GP model. By the comparison of the precipitation amounts under different return levels, it can be found that the values obtained from POT series are a little larger than the values from AM series, and they can better simulate the observed values in the Huaihe River Basin.     

塔克拉玛干沙漠沙垄区公路防护带内风场特征研究

塔克拉玛干沙漠公路是世界上穿越流沙区最长的公路,公路两侧防沙治沙工程体系是公路正常运行的关键因素。以塔克拉玛干沙漠沙垄区的公路防护林带为研究对象,结合野外地形测量、防护工程调查以及风沙数据观测,分析沙垄不同地貌部位防护林带内气流特征,揭示防护林带内风场变化规律,探讨不同地貌部位防护林带的防护效果。主要结论是:①垂直于公路的防护林带断面风场存在3个区(防护林带前部风速迅速降低区、防护林带中部风速低值区、防护林带工程后部风速恢复区),气流穿过公路路面时风速呈增大趋势,利于公路防护;②现有防护林带具有较好的防护效果,相对于防护林带上风向流沙区的风速,防护林带中部风速降低幅度在80%以上,多数断面在林带前缘10H后（H为植株平均高度）风速降低至最小;③沙垄不同地貌部位的工程防护效益存在显著差异,迎风坡底部防护效果最好,迎风坡中部防护最差。其研究结果可为塔克拉玛干沙漠公路防沙治沙工程体系优化提供科学依据。     

中国地理学史编史方法论考察

基于编史学视角对国外地理学史著作的中国部分以及中国地理学史著作的考察,重点论述了实证主义和思想史两类编史方法论特征。考察表明:国外实证主义地理学史以实证主义方法论为核心,是一种普遍主义和进步主义的叙事模式,这种模式里并不存在实质性的中国古代地理学,而中国近代地理学则是欧美地理学的移植。在后历史的立场上,对地理学应作宽泛的理解,实证主义地理学史是建构的历史,中国学者遵循实证主义方法论的重要意义在于建构了中国地理学理性的一面。中国地理学史人文的方面是通过思想史方法论建构起来的,这种方法通过中国古代原有文化体系、观念、概念、材料来认识地理学的发展史,首要的意义是与实证主义建构相反的还原。基于思想史方法论的中国近代地理学史研究表明,中国近代地理学的形成首要的并不是西方地理学的移植,而是自主地基于中国古代传统的学术重构,反映的是中西学术的双向互动,并不是西方地理学的单向传播。     

新疆地区表土孢粉空间分布规律研究

中国新疆地区表土花粉研究结果展示了干旱区主要孢粉的空间分布规律,大部分表土花粉属种的地理空间分布与含量与相应植物的分布区域基本一致,藜科、蒿属、麻黄属及木本植物云杉属、桦木属等花粉普遍呈超代表性,柽柳属花粉呈低代表性。干旱区主要草灌木表土花粉数据的聚类分析结果可以基本反映本区植物群落的主要生态组合类型。主成分分析进一步表明该区草本和灌木花粉分布主要受水文和湿度等因素控制。     

自润滑孕镶金刚石钻头胎体材料初步研究

为了研究具有自润滑性能的孕镶金刚石钻头胎体材料,进行了在胎体配方中添加石墨的研究。对胎体材料的抗弯强度、硬度、耐磨性和材料与白刚玉砂轮组成摩擦副时的摩擦系数进行了测定,并用扫描电子显微镜观察了磨损表面形貌。实验结果表明,添加石墨后,胎体材料的硬度和抗弯强度下降,与60目白刚玉砂轮组成摩擦副时的摩擦系数下降,耐磨性则随着石墨含量的增多先增强,后下降（超过6％后）。形貌分析表明,不含石墨的胎体材料在磨损中发生明显的塑性变形;添加石墨后,胎体材料的塑性降低,出现犁沟和剥落现象。     

基于GM(1,1)模型的塔里木盆地南缘孤立绿洲降水灾变预测

我们选取了具有一定代表性的塔里木盆地南缘的孤立绿洲民丰县作为研究区,在对数据有效性的验证之后,利用研究区1980~1999年的降水资料,运用灰色系统理论的季节灾变预测方法,对该地区未来年份的降水量进行预测,并建立灰色季节灾变GM(1,1)预测模型,预测未来旱季到来的年份,为预测未来降水趋势提供了信息。结果表明:该研究区下一个旱灾灾变年大致指向2006年至2007年左右。这对合理利用本地气候资源具有实际意义,并且能够为研究干旱区气候变化提供一定的帮助。     

STPIR和MW组合的北斗三频周跳探测与修复

针对载波相位观测值中出现周跳的问题及北斗卫星导航系统全星座播发三频信号的现状,提出一种三频相位电离层残差二阶历元差分(STPIR)的算法,克服了传统电离层残差法受观测数据采样间隔影响较大的问题,联合MW组合观测量进行周跳探测又可避免各自的探测盲区。两种组合观测量均很好地削弱了电离层延迟项的影响,联立方程组进行周跳求解时,直接取整即可得到周跳值。通过北斗三频实测数据验证,提出的组合方法在观测数据采样间隔较大时,可以准确探测出所有周跳,并有效修复。     

Mosaic desert pavement influences water infiltration and vegetation distribution on fluvial fan surfaces

Desert pavements (DPs) are critical for maintaining ecological stability and promoting near-surface hydrological cycling in arid regions. However, few studies have focused on eco-hydrological processes of DPs in the ecological systems of fluvial fans. Although DP surfaces appear to be barren and flat, we found that the surfaces are characterized by surface mosaic patterns of desert pavement (mosaic DP) and bare ground (mosaic BG). We investigated the effects of mosaic DP on water infiltration and vegetation distribution at six sites in fluvial fans (one on a hillside and five within the sectors of fans) along a southwest belt transect in northern Linze County, in the central Hexi Corridor (China). We found significant differences in mosaic DP between the hillside and sector sites in terms of pavement thickness and vesicular horizon thickness (Av thickness), particle composition, and bulk density, although significant differences were absent for mass soil water content, gravel coverage, and surface gravel size. The mosaic DP inhibited water infiltration by the pavement layer, where the sorptivity (S), initial infiltration rate (i_int), steady-state infiltration rate (i_sat) and infiltration time (T) averaged 1.19 cm/min^-0.5, 0.64 cm/min, 0.13 cm/min and 12.76 min, respectively. Where the pavement layer was scalped, the S, i_int, and i_sat increased by 0.27 cm/min^-0.5, 0.52 cm/min, and 0.40 cm/min, respectively, and the T reduced by 7.42 min. Water infiltration was mainly controlled by the pavement layer thickness (+), Av thickness (−), surface gravel coverage (−), fine earth (+) and fine gravel (−) in the pavement layer. The DP surfaces only had a sparse covering of shrubs, but an abundance of herbs. Few shrubs were present on the mosaic DP, but a greater number of shrubs and herbs grew on the mosaic BG. It can be concluded that DPs can maintain vegetation stability for different surface mosaic patterns. This study deepens our understanding of the eco-hydrological cycle of DP landscapes in arid regions.     

汶川等巨震前M≥5地震活动对比研究

本文对汶川、昆仑山口西、察隅和海原等8级巨震前震中距半径15°范围内,震前10年M≥5地震活动的对比研究表明,地震频度和强度的异常表现形式可分为大范围活跃、平静和局部活跃三种,异常展布范围半径为(600±200)km,异常分布受青藏亚板块边界断裂控制,边界断裂外异常不明显。震前无论活动频度或强度的异常增强或减弱,均以未来震中所在和相邻地块(或省区)最明显,异常强度多以突破其历史极值为特征,向外则逐渐减弱。研究区或震中所在省区M≥5地震累计年频次异常,多数于震前1~2年出现高值,个别出现在震前4年。8级巨震震中区均为M≥5地震的弱活动或异常平静区,一般表现为围空区,少数为活动条带,空区大小总体上与震级成正相关。     

大岗山水电站坝肩边坡开挖支护有限元模拟

大岗山水电站坝肩边坡地质条件复杂,断层、岩脉、卸荷裂隙密集带、深部卸荷带及节理裂隙发育。为对该边坡在开挖支护过程中的应力、变形情况进行分析,采用弹黏塑性有限元软件EVP3D,利用弹塑性有限元法进行边坡稳定性的三维有限元计算,揭示边坡可能的失稳部位,对初拟的施工程序的合理性进行评价,并对边坡的支护方案提出建议。