近50 a鄂西山区雾和轻雾发生频次的非对称变化特征

以湖北西部山区宣恩站为例,利用1959-2009年的地面气象观测资料,对鄂西山区雾和轻雾的气候特征进行分析.结果表明,宣恩年雾日数平均为29 d,总体上呈减少趋势.该地区雾在每个月都有发生,冬季发生频率最高,夏季发生频率最低;该地区年轻雾日数总体上与年雾日数变化趋势相反,呈上升趋势,各月月平均轻雾日数在9~15 d之间,12月平均轻雾日最多,5月平均轻雾日最少.通过分析宣恩51 a来各气象要素的特征发现,夜晚最低气温呈上升趋势,相对湿度和降水变化不明显,14时能见度≥20 km的年日数呈下降趋势.分析认为,雾和轻雾发生频次的非对称变化趋势可能与大气中气溶胶粒子增多有关.     

New Zircon U‐Pb Age of Late Devonian Tuff in Guangxi,South China and the Significance for the Paleo‐Tethys Branch Ocean

正Objective The eastern extending range of the Paleo-Tethys Ocean in southwest China has always been focused and controversial.At the beginning of this century some scholars proposed that the Paleo-Tethys Branch Ocean may extend to the Babu–Pingxiang and Cengxi areas along the stouthwestern margin of the South China Block(Cai and Zhang,2009).However,the pivotal proof of Late     

近景摄影测量技术在核电压力容器三维测量中的应用

本文主要论述近景摄影测量技术在"华龙一号"核电厂反应堆压力容器安装中的应用,为满足反应堆主系统安装的高精度技术要求,须对压力容器本体进行三维尺寸测量,获取安装所需的精确尺寸数据.本方法采用摄影测量技术对压力容器本体特征点进行拍摄,采用专用软件匹配影像和采集像素点信息,对采集的数据进行分析处理,光束法平差后数据与相关设计数据进行对比分析,计算得出设备定位所需的尺寸数据.通过近景摄影三维测量技术实现了压力容器本体尺寸数据的高质和高效采集,满足了主系统安装的技术需求.     

外部性脑积水的CT与临床分析

探讨外部性脑积水（ＥＨ）的ＣＴ与临床表现特点及关系。材料与方法：搜集２４例ＥＨ的ＣＴ资料进行分析,并对其中１０例进行了临床与ＣＴ复查．结果：２４例ＣＴ上均有不同程度额顶部蛛网膜下腔增宽,大脑前纵裂增宽,并多伴有基底池扩大．复查显示,３个月全部为典型表现,６～１２个月ＣＴ征象逐渐减轻,２４个月大部分病例逐渐或完全恢复正常．临床症状随之减轻或消失．结论：ＥＨ是发生在婴儿早期的良性自愈性疾病,预后良好．     

自动气象站运行、维护及自动站数据与人工观测资料的对比分析

基本(准)站气象台站目前采集地面气象资料均采用两套设备。一套是人工观测，通过传统的目测和直接感应的观测方法；另一套是通过地面有线综合遥测仪自动采集每个正点的压、温、湿、风、降水、地温等气象要素。通过对运行一年来自动观测站与人工观测站各气象要素资料的对比分析，找出自动站观测资料与人工观测资料之间的差异，为气象资料的连续使用提供依据。     

准噶尔盆地阜康凹陷侏罗系超压成因、垂向传导及油气成藏

沉积盆地中超压广受关注,但对超压传导规律认识的不足制约了高压领域的油气勘探.以准噶尔盆地阜康凹陷侏罗系为例,通过超压类型地质综合判识、关键超压表征参数的理论计算及流体包裹体压力恢复,首次认识到了垂向传导对于储集层超压的重要贡献,结合压力垂向传导机制及过程,探讨了油气藏的运聚及泄露意义.研究结果表明,侏罗系超压由4类超压环境中7种致压因素引起,经历2期大规模压力跨层垂向传导,储集层段发育以垂向传导为主因的复合超压,形成3类不同动力特征的油气藏.压力垂向传导是储集层超压的主要成因机制,断-盖的力学性质、差应力及流体压力等3类因素控制压力垂向传导,传导背景下,形成3类与传导作用有关的油气藏:受断层垂向传导控制的超压油藏、受连通砂体侧向传导控制的超压油藏以及超压界面上的常压油藏,上述3类油气藏的运聚及泄露特征差异较大.      

吐鲁番市荒漠化风险动态变化及驱动力分析

荒漠化是当今最为严重的生态问题之一,开展荒漠化风险量化评估,有助于荒漠化风险调控,实现区域生态经济可持续发展.通过从气候、下垫面和社会经济等因素选取指标,构建吐鲁番市荒漠化风险评价体系,基于3S技术分析评估其2000—2018年的荒漠化风险程度,并采用地理探测器进行驱动力分析.结果表明:(1)2000—2018年吐鲁番...     

Nutrient fluxes induced by disturbance in Meiliang Bay of Lake Taihu

A wave flume experiment was conducted to study nutrient fluxes at water-sediment interface of Meiliang Bay under different hydrodynamic conditions. The results reveal that hydrodynamics has remarkable effects on nutrient fluxes in this area. With a bottom wave stress of 0.019 N m-2 (equivalent to disturbance caused by wind SE 5-7 m s-1 at the sediment sample site of Meiliang Bay), the fluxes of TN, TDN and NH4+-N were separately 1.92× 10-3, -1.81 × 10-4 and 5.28× 10-4 mg m-2 s-1(positive for upward and negative for downward), but for TP, TDP and SRP, the fluxes were 5.69 × 10-4, 1.68 × 10-4 and -1.29 × 10-4 mgm-2 s-1. In order to calculate the released amount of nutrients based on these results, statistic analysis on the long-term meteorological data was conducted.The result shows that the maximum lasting time for wind SE 5-7 m s-1 in this area is about 15 h in summer. Further calculation shows that 111 t TN, 32 t NH4+-N, 34 t TP and 10 t TDP can be released into water (the sediment area was 47.45% of the whole surface area), resulting in concentration increase of 0.025, 0.007, 0.007 and 0.002 mg L-1 separately. With stronger disturbance (bottom wave stress is 0.217 N m-2 which is equivalent to disturbance caused by wind SE 10-11 m s-1 at the same site), there has been significant increase of nutrient fluxes (1.16× 10-2, 6.76×10-3, 1.14× 10-2 and 2.14× 10-3 mgm-2 s-1 for TN, DTN and NH4+-N and TP). The exceptions were TDP with flux having a decrease (measured to be 9.54× 10-5 mgm-2 s-1 ) and SRP with flux having a small increase (measured to be 5.42 × 10-5 mgm-2 s-1). The same statistic analysis on meteorological data reveal that the maximum lasting time for wind SE 10-11 m s-1 is no more than 5 h. Based on the nutrient fluxes and the wind lasting-time, similar calculations were also made suggesting that 232 t TN, 134.9 t TDN, 228 t NH4+-N, 42.7 t TP, 2.0 t TDP and 1.1 t SRP will be released from sediment at this hydrodynamic condition resulting in the concentration increases of 0.050, 0.029, 0.049, 0.009, 0.0004 and 0.0002 mg L-1. Therefore in shallow lakes, surface disturbance can lead to significant increase of nutrient concentrations although some components in water column had negative flux with weak disturbance (e.g. TDN and SRP in this experiment). In this case, sediment looks to be a source of nutrients. These nutrients deposited in sediment can be carried or released into water with sediment resuspension or changes of environmental conditions at water-sediment interface, which can have great effects on aquatic ecosystem and is also the characteristics of shallow lakes.