Zircon evaporation ages and geochemistry of metamorphosed volcanic rocks from the Vinjamuru domain,Krishna Province: evidence for 1.78 Ga convergent tectonics along the southeastern margin of the Eastern Dharwar Craton

Palaeoproterozoic intermediate to potassic felsic volcanism in volcano‐sedimentary sequences could either have occurred in continental rift or at convergent magmatic arc tectonic settings. The Vinjamuru domain of the Krishna Province in Andhra Pradesh, SE India, contains such felsic and intermediate metavolcanic rocks, whose geochemistry constrains their probable tectonic setting and which were dated by the zircon Pb evaporation method in order to constrain their time of formation. These rocks consist of interlayered quartz–garnet–biotite schist, quartz–hematite–baryte–sericite schist as well as cherty quartzite, and represent a calc‐alkaline volcanic sequence of andesitic to rhyolitic rocks that underwent amphibolite‐facies metamorphism at ~1.61 Ga. Zircons from four felsic metavolcanic rock samples yielded youngest mean ²⁰⁷Pb/²⁰⁶Pb ages between 1771 and 1791 Ma, whereas the youngest zircon age for a meta‐andesite is 1868 Ma. A ~2.43 Ga zircon xenocryst reflects incorporation of Neoarchaean basement gneisses. Their calc‐alkaline trends, higher LILE, enriched chondrite‐normalized LREE pattern and negative Nb and Ti anomalies on primitive mantle‐normalized diagrams, suggest formation in a continental magmatic arc tectonic setting. Whereas the intermediate rocks may have been derived from mantle‐source parental arc magmas by fractionation and crustal contamination, the rhyolitic rocks had crustal parental magmas. The Vinjamuru Palaeoproterozoic volcanic eruption implies an event of convergent tectonism at the southeastern margin of the Eastern Dharwar Craton at ~1.78 Ga forming one of the major crustal domains of the Krishna Province. Copyright © 2012 John Wiley & Sons, Ltd.     

近年来山西中部地区水雨情及旱情旱灾分析

分析了山西中部地区20世纪70年代以后的降雨、流量、蒸发量的时空分布。山西中部地区降雨偏少,年际丰枯变化大,年内分布不均。70年代以来径流在逐渐减少,2000年以后径流的减少更为明显。90年代以后蒸发量增大。分析了90年代以来该地区发生的农业受旱、粮食旱灾情况,降雨、流量、蒸发量是影响旱情旱灾发生的重要因素。     

NBB-390～52/11～8型变量泥浆泵的研制与应用

为了满足深层岩心钻探的需要,在分析了目前市场上现有同类泥浆泵的优缺点的基础上,提出了新型泥浆泵主要应解决的问题;介绍了NBB-390～52/11～8型变量泥浆泵的主要组成部分、特点、技术参数以及试验情况。     

Void distributions in samples of Ottawa sand

The void distribution of saturated specimens of Ottawa sand is presented. The presence of water inside the sand specimen is detected using the magnetic resonance imaging (MRI) technique. The void distribution of the sample was determined from the image. The specimen was prepared in a non-metallic triaxial cell and was put insie a MRI apparatus to obtain the image. Two sample preparation methods (wet tamping and dry pluviation) were used to illustrate the uniformity of the samples in the initial state. The void distribution along the height of the sample and the three-dimensional orientational void distribution at different locations inside the sample were analysed. The results indicate that the sample generated by the dry-pluviation method is more uniform than the sample generated by the wet-tamping method. When the wet-tamping sample preparation technique is used, the dense sample is more uniform than the loose sample. The development of voids was investigated by a sample loaded inside the MRI device under drained compression condition. The void distribution along the height of the sample at different stages was observed. This work has demonstrated the feasibility of using the MRI technique to examine void distribution in granular material.     

基于熵值与关联分析法的塔里木河下游区域水面蒸发影响因子敏感性研究

水面蒸发敏感因素的判断,对于干旱区水资源的规划与利用具有重要指导意义。文章以新疆塔里木河下游铁干里克气象站2005年资料为例,对研究区水面蒸发影响因素进行分析。采用熵值法对水面蒸发进行敏感性分析,并与关联分析法分析结果进行对比。结果表明：在塔里木河下游铁干里克地区,温度与风速二因素对水面蒸发影响最为敏感;基于熵值法的敏感因素研究结果与关联分析的结果基本一致。     

春秋季节侧柏-山毛桃群落演替初期的小气候特征

开展森林小气候研究,对于协调生物与环境的关系、保护生物多样性以及实现森林的可持续高效管理,都是十分重要的。选择5月和10月典型的晴朗无风天气条件,以侧柏纯林为对照,研究了郁闭度为0.25、0.54和0.87的侧柏-山毛桃群落演替初期小气候特征。结果表明,侧柏-山毛桃混交林对春季和秋季林内空气温度的早间增温效应和午间降温效应,随着郁闭度增加而增大。春季的高温峰值出现在15时,晚于秋季的高温峰值13时。春季和秋季林内10 cm处地温日间呈持续增加趋势,春季以郁闭度为0.25的B点为最高,秋季侧柏纯林在12时前为最低,14时后为最高。春季林内空气相对湿度从07时到11时呈快速降低的趋势,然后逐渐缓慢回升;而秋季林内的相对湿度,随着郁闭度的增加而增大,但日间变化幅度比较小。无论春季还是秋季,侧柏和山毛桃的叶片温度日间变化均呈先升高后缓慢降低的趋势。春季郁闭度对侧柏和山毛桃的叶片温度影响不显著,但秋季11-15时,随着郁闭度的增加,叶片温度有降低的趋势。在太行山区,以山毛桃为保护树种,快速提高侧柏-山毛桃混交林的郁闭度,对有效地改善林内小气候,促进森林更新和管理都是十分重要的。     

湿静力平衡温度及其在大气对流运动中的应用

提出了一个新的大气动力-热力学温湿参量——湿静力平衡温度（T_s）。它与密度温度（T_ρ）有密切关系。作为T_s的应用示例,简化了积云一维时变模式垂直运动方程;提出了“载水气块”和“非载水气块”统一的新的“对流有效位能”表达式。结合实例,计算了“载水气块”和“非载水气块”两种情况下的对流有效位能（分别记作CAPE_w和CAPE）以及对流抑制能量（分别记作CIN_w和CIN）等,“载水气块”与“非载水气块”两种情况的“对流有效位能”及“对流抑制能量”有较大差异。作为强对流天气分析预报的重要参数,目前计算对流有效位能和对流抑制能量的通用公式存在一定缺陷;在对“对流有效位能”的理解方面存在某些模糊认识和盲点。从新的观察角度对“对流有效位能”的概念做了详细分析并进一步阐明了其确切含义。新的方案同样可以方便地在T-lnp图上进行稳定度分析,并可根据新的公式对T-lnp的某些缺点进行修正。     

Bias-Corrected Short-Range Ensemble Forecasts for Near-Surface Variables during the Summer Season of 2010 in Northern China

A running mean bias （RMB） correction ap- proach was applied to the forecasts of near-surface variables in a seasonal short-range ensemble forecasting experiment with 57 consecutive cases during summer 2010 in the northern China region. To determine a proper training window length for calculating RMB, window lengths from 2 to 20 days were evaluated, and 16 days was taken as an optimal window length, since it receives most of the benefit from extending the window length. The raw and 16-day RMB corrected ensembles were then evaluated for their ensemble mean forecast skills. The results show that the raw ensemble has obvious bias in all near-surface variables. The RMB correction can remove the bias reasonably well, and generate an unbiased ensemble. The bias correction not only reduces the ensemble mean forecast error, but also results in a better spreaderror relationship. Moreover, two methods for computing calibrated probabilistic forecast （PF） were also evaluated through the 57 case dates： 1） using the relative frequency from the RMB-eorrected ensemble; 2） computing the forecasting probabilities based on a historical rank histogram. The first method outperforms the second one, as it can improve both the reliability and the resolution of the PFs, while the second method only has a small effect on the reliability, indicating the necessity and importance of removing the systematic errors from the ensemble.     

高精度对流层天顶湿延迟模型研究

对流层湿延迟是GPS误差源中最难确定的量,鉴于目前的对流层湿延迟模型较少考虑相对湿度随高度变化对湿延迟估计的影响,文章根据对流层湿延迟折射率的变化特征,提出新的分段湿延迟模型TTZWD.通过实验证明TTZWD湿延迟精度较Saastamoinen模型有不同程度的提高,与IGS后处理结果吻合精度好,基本可以达到半波长以内.实验还证明在相对湿度未知的情况下,将相对湿度设置为1,TTZWD模型依然可以使用,与相对湿度已知时的精度相当.     

Evaluating the Efficiency of Typographic Design: Gender and Expertise Variation

Abstract

Although the efficiency of label placement algorithms has been studied extensively, few studies considered the influence of the label designs on the efficiency of map readers. Labels are one of the most important elements on the map as they can provide more information than other symbols can. The design of the labels does have to stress the theme, shape and functionality of the associated objects, which results in a more efficient interpretation of the map content by the user. How the label designs can enhance the map readers’ efficiency (and thus the quality of the maps themselves) is the main objective of this study. A user study was conducted in which the participants were asked to locate a target label on a map. Different label designs were implemented across the trials. The participants’ reactions times were registered to measure their efficiency and statistically analysed using a one-way ANOVA. Two different users’ characteristics were considered: gender and expertise. Related to the size, shape, orientation and texture of the labels, a number of significant differences (P<0·05) and trends were located. Differences in efficiency between males and females, on the one hand, and between novices and experts, on the other hand, were also described statistically. Consequently, recommendations can be formulated regarding the design of labels in order to obtain more efficient maps, keeping in mind the map users’ characteristics.