基于非等间距泊松曲线在沉降预测中的应用

泊松曲线是一种精度较高的沉降预测方法，但是它只能在等时距数据条件下方能使用，在工程实际中很难满足这一要求。本文采用插值法将非等时距数据转化成等时距数列，并结合高层建筑沉降监测工程实例分析，结果表明，用泊松曲线模型预测建筑物沉降量与实际沉降量比较接近，具有较高的应用价值。     

长江三峡库区梯田稳定性分析与对策*──以鄂西秭归县为例

三峡库区历史上就是滑坡、崩塌作用强烈的地带,在调查分析秭归县滑坡、崩塌对梯田稳定性的影响的基础上,探讨了四种不稳定梯田培坎的特征、性质和现状,提出了利用优势植物固土护坎等相应的对策。     

Housing privatization and the return of the state: changing governance in China

Housing privatization seems to suggest a process of state retreat. However, this is not always the case in China. This paper examines an estate that is mixed with work-unit housing and municipal public housing to understand its changing governance. It is intriguing to observe that the state has had to return to this neighborhood to strengthen its administration following housing privatization, because the attempt to transfer responsibility to commercial property management failed. The neighborhood governance, however, has transformed from one based on work-units to a government-funded administrative agency. The return of the state has been achieved through professional social workers, and it is struggling to operate, leading to the alienation and disempowerment of former state work-unit residents. The side effect of this approach to governance is that, through encouraging market provision and commercial operation which is not fully working, reciprocal activities are restrained. Since housing privatization, the neighborhood has deteriorated from a brand-new estate into an ‘old and dilapidated neighborhood’ in less than 25 years.     

Subseasonal variability during the South China Sea summer monsoon onset

Analysis of the Tropical Rainfall Measuring Mission (TRMM) Microwave Imager (TMI) data for the period 1998–2007 reveals large subseasonal fluctuations in sea surface temperature (SST) of the South China Sea during the summer monsoon onset. These subseasonal SST changes are closely related to surface heat flux anomalies induced by surface wind and cloud changes in association with the summer monsoon onset. The SST changes feed back on the atmosphere by modifying the atmospheric instability. The results suggest that the South China Sea summer monsoon onset involves ocean–atmosphere coupling on subseasonal timescales. While the SST response to surface heat flux changes is quick and dramatic, the time lag between the SST anomalies and the atmospheric convection response varies largely from year to year. The spatial–temporal evolution of subseasonal anomalies indicates that the subseasonal variability affecting the South China Sea summer monsoon onset starts over the equatorial western Pacific, propagates northward to the Philippine Sea, and then moves westward to the South China Sea. The propagation of these subseasonal anomalies is related to the ocean–atmosphere interaction, involving the wind-evaporation and cloud-radiation effects on SST as well as SST impacts on lower-level convergence over the equatorial western Pacific and atmospheric instability over the Philippine Sea and the South China Sea.     

中生代复杂构造体系的成矿过程与成矿作用——以华北大陆北缘西拉木伦钼铜多金属成矿带为例

西拉木伦钼铜多金属成矿带处于华北克拉通与中亚造山带的过渡区,是古生代古亚洲构造域与中生代西太平洋构造域的交汇部位。在中生代受多种构造体系的制约,如中亚造山带造山后期局部伸展、蒙古-鄂霍茨克俯冲-碰撞造山作用、古太平洋板块的向西俯冲和中国东部岩石圈减薄事件的影响等。西拉木伦成矿带成矿斑岩锆石U-Pb年龄和辉钼矿Re-Os同位素年龄资料显示,钼铜矿成岩成矿主要集中在260～220Ma、180～150Ma和140～120Ma三个时期。结合华北克拉通北缘构造演化历史,推测这三期成矿作用主要与造山后局部伸展、构造体系转折和陆内伸展(岩石圈减薄)过程有关,并相应建立了"车户沟式"、"鸡冠山式"和"敖伦花式"三类斑岩钼铜矿床成矿模式。进一步研究表明,岩石的酸碱性、岩浆来源、岩浆的氧逸度、岩浆演化方式、构造背景等因素,制约了成矿作用的专属性。     

内蒙古白银都西群变质火山岩的钕、锶同位素研究

白银都西群主要由斜长角闪岩、变粒岩、长英片岩和条带状混合岩组成,是白银都西-白乃庙地体的重要组成部分,主要分布在内蒙古白乃庙铜(金)矿床东北白银都西一带。长期以来,由于缺乏可信的同位素年龄数据,该套岩层的归属,构造性质和形成机理尚不清楚。笔者首次对白银都西群斜长角闪岩的Nd和Sr同位素组成进行了测定,所获Sm-Nd同位素等时年龄为1394±46Ma(23),Nd初始比值为0.511 243±8(23)和εNd(T)=+7.9±2.1(23)。~(87)Sr/~(86)Sr和~(87)Rb/~(86)Sr比值分别为0.705 79—0.709 12和0.17—0.34,两者之间不存在任何相关关系。结合野外地质证据和岩相学特征,我们认为:白银都西群基性火山活动发生在中元古代,成岩物质来自亏损地幔源,成岩以后构造变动和变质热液活动致使Rb-Sr同位素体系受到严重干扰破坏。     

河南省森林火险月季尺度定量客观化预测

基于火灾资料和气象资料,利用数理统计方法和百分位法,分析了河南省林区火灾的气候特征及防火关键期高火险日数的月、季气候特征。结果表明,林区火灾次数年际波动较大,主要出现在每年的冬春季(12月次年4月),3月出现的次数最多,2月的次之。火灾峰值主要出现在13-16时。3月高火险日数存在显著增加的线性趋势,12月和1月高火险日数呈现先减少后增加的趋势。2月和4月高火险日数处在偏少的年代际背景下。林区春季高火险日数存在显著增加的线性趋势,在桐柏-大别山林区尤其明显。选取河南省防火关键期各月、季高火险日数与海温、积雪、环流场等130项环流指数的相关关系最好的因子,利用最优子集回归分别建立基于林区内各个气象站点的预测方程。通过回代检验和趋势异常综合评分(Ps),对回归方程预测效果进行检验,结果显示,回代曲线和历史曲线吻合好,表明预测方程预测结果接近实况。     

一次飞机严重积冰的天气条件和云微物理特征

利用2021年2月28日机载探测资料, 结合欧洲中期天气预报中心ERA5再分析资料、陕西省延安站探空资料, 分析飞机发生严重积冰的天气背景和云的宏微观结构特征。此次严重积冰天气是受高空槽、低空切变线、低空急流和地面冷锋共同影响的结果。ERA5再分析资料表明:过冷水大值区主要分布于锋区前部暖侧的700 hPa至600 hPa高度。探空资料表明:飞机探测区环境温度为-9~-3℃, 温度露点差为0℃, 具有发生严重积冰的温度和湿度条件。飞机遭遇严重积冰期间环境温度为-8~-5℃, 云粒子探头观测的液态水含量平均为0.35 g·m-3, 最大为0.7 g·m-3;总水含量仪观测的液态水含量平均为0.5 g·m-3, 最大为0.85 g·m-3, 有11 min大于0.45 g·m-3;云粒子中值体积直径平均为20.3 μm, 云粒子数浓度平均为149.3 cm-3;云粒子数浓度由低层到高层呈增大趋势, 而云粒子中值体积直径变化趋势与之相反。计算表明:国王350飞机在穿云作业时, 云中过冷水含量分别高于0.04 g·m-3, 0.15 g·m-3和0.45 g·m-3时可能遭遇轻度积冰、中度积冰和严重积冰。     

探测仪器特性曲线异常分析

探测仪器感应曲线发生变化,造成升速异常、等压面的温度、湿度错误、雷达〖CD*2〗气压高差偏大、时间〖CD*2〗高度线曲变化异常造成的规定高度上的风误差偏大,使部分资料或整份资料失真,影响探测准确性。本文主要从仪器的感应曲线变化后对各气象要素产生的影响进行分析,得出结论：不同的元件变性对气象要素产生的影响不同,气压变化的影响侧重于高差和升速,温度变化则侧重于规定等压面的温度绝对误差和规定等压面高度的偏差。采用绝对误差计算、加密气象要素计算等方法,结合图形、数据对比,可以确定感应曲线变化时间,从而及时、有效的对探测数据做出合适的处理,进一步提高探测数据的精准度。     

塔中地区志留系碎屑锆石测年及其地质意义

志留系是塔里木盆地第一套砂岩储层广泛分布的沉积盖层,其沉积来源与成因对志留纪构造演化及周边造山带的研究具有重要意义。塔中地区3个志留系样品的碎屑锆石LA?ICP?MS U?Pb定年研究表明,志留系具有比较集中的二期物源年龄：南华纪中期、古元古代中期。碎屑锆石测定的年龄表明塔中志留系物源均来自前寒武纪,塔中东部源区方向的塔南隆起基底在奥陶纪已隆升成为蚀源区。大量的新元古代中期锆石年龄表明塔里木板块在新元古代时期可能与Rodinia超大陆具有相似的聚合与裂解演化史。