天山古生代增生造山作用及其构造转换事件     

王博  宋芳  倪兴华  曹婷婷  刘珈硕  钟凌林  孙朝晨  孙雨欣  邓聚  李盈莹  朱鑫  刘洪升  何智远 《地质学报》2022,96(10):3514-3540

天山造山带自新元古代以来，经历了漫长而复杂的俯冲增生造山作用和陆内构造活化过程，属于典型的复合型造山带。基于近年研究进展，本文对伊犁、境内外中天山和南天山构造带前寒武纪基底、古生代沉积序列、多期陆缘弧岩浆岩和构造缝合带的变形变质特征、形成环境和年代学等进行了总结分析，梳理了天山古生代增生造山作用中的三次重要构造转换事件及其地质记录。① 伊犁南北两缘、中天山、南天山和塔里木北缘，均发育中奥陶世—志留纪的大陆弧岩浆作用，伊犁北缘、南天山 塔里木北部早古生代沉积环境发生显著变化，表明天山 塔里木北缘在中—晚奥陶世发生了从被动陆缘向活动陆缘的转换。② 伊犁南、北两缘和中天山的早古生代岩层在晚志留世—早泥盆世普遍发生了强烈的韧性变形和角闪岩相变质作用，其上不整合覆盖有弱变形未变质的晚泥盆世—石炭纪火山 沉积地层；该区域不整合是哈萨克斯坦微大陆拼合事件在研究区的构造响应，也标志着准噶尔洋和南天山洋的俯冲方式在泥盆纪发生了由前进式（东太平洋型）向后撤式（西太平洋型）的构造转换，导致伊犁和中天山在晚泥盆世—石炭纪经历了伸展背景下的大陆弧岩浆作用，在南天山 塔里木北缘则形成了一系列弧后有限洋盆。③ 天山各构造单元及其边界缝合带中普遍发育晚石炭世逆冲推覆构造和二叠纪走滑韧性剪切带、晚石炭世—早二叠世滑塌堆积和二叠纪后造山岩浆岩，指示晚石炭世—早二叠世发生了由汇聚造山向陆内构造的转换。这些构造转换事件是认识古亚洲洋各分支洋盆从初始俯冲、俯冲方式转换到俯冲终结过程的基础，也是探讨增生造山动力学的关键。  相似文献   

Characteristics of Turbulent Transfer during Episodes of Heavy Haze Pollution in Beijing in Winter 2016/17     

Yan?Ren  Shuwen?Zheng  Wei?Wei  Bingui?Wu  Hongsheng?ZhangEmail author  Xuhui?Cai  Yu?Song 《Acta Meteorologica Sinica》2018,32(1):69-80

We analyzed the structure and evolution of turbulent transfer and the wind profile in the atmospheric boundary layer in relation to aerosol concentrations during an episode of heavy haze pollution from 6 December 2016 to 9 January 2017. The turbulence data were recorded at Peking University’s atmospheric science and environment observation station. The results showed a negative correlation between the wind speed and the PM_2.5 concentration. The turbulence kinetic energy was large and showed obvious diurnal variations during unpolluted (clean) weather, but was small during episodes of heavy haze pollution. Under both clean and heavy haze conditions, the relation between the non-dimensional wind components and the stability parameter z/L followed a 1/3 power law, but the normalized standard deviations of the wind speed were smaller during heavy pollution events than during clean periods under near-neutral conditions. Under unstable conditions, the normalized standard deviation of the potential temperature σ _θ /|θ_*| was related to z/L, roughly following a –1/3 power law, and the ratio during pollution days was greater than that during clean days. The three-dimensional turbulence energy spectra satisfied a –2/3 power exponent rate in the high-frequency band. In the low-frequency band, the wind velocity spectrum curve was related to the stability parameters under clear conditions, but was not related to atmospheric stratification under polluted conditions. In the dissipation stage of the heavy pollution episode, the horizontal wind speed first started to increase at high altitudes and then gradually decreased at lower altitudes. The strong upward motion during this stage was an important dynamic factor in the dissipation of the heavy haze.  相似文献   

Review of the Field Measurements and Parameterization for Dust Emission During Sand-Dust Events          下载免费PDF全文

ZHANG Hongsheng  LI Xiaolan 《Acta Meteorologica Sinica》2014,28(5):903-922

Dust emission generated by wind erosion is a basic process before the transport and deposition of dust particles. Parameterization of dust emission flux is important for accurate simulation and prediction of dust events. Field observation and numerical simulation are two approaches to understand the complex process of dust emission. Great progress has been made on the characteristics and mechanism of dust emission during dust storm events. This review introduces the major factors influencing dust emission and summarizes the calculation methods of several key parameters of dust emission, including the threshold friction velocity u.t, threshold wind speed Ut, streamwise saltation flux Q, and （vertical） dust emission flux F, from perspectives of both observation and parameterization. The paper also discusses the improvement, application, and validation of different dust emission schemes in dust models. Existing problems and future research directions are elaborated as well.  相似文献   

Transcription profiling using RNA-Seq demonstrates expression differences in the body walls of juvenile albino and normal sea cucumbers Apostichopus japonicus     

马得友  杨红生  孙丽娜  陈慕雁 《中国海洋湖沼学报》2014,32(1):34-46

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Selection of reference genes for qRT-PCR analysis of gene expression in sea cucumber Apostichopus japonicus during aestivation     

赵业  陈慕雁  王天明  孙丽娜  徐冬雪  杨红生 《中国海洋湖沼学报》2014,32(6):1248-1256

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Profiling and comparison of color body wall transcriptome of normal juvenile sea cucumber (Apostichopus japonicus) and those produced by crossing albino     

Deyou Ma  Hongsheng Yang  Lina Sun 《中国海洋大学学报(英文版)》2014,13(6):1033-1042

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上海浦东国际机场低层大气垂直风场特征研究   总被引：1，自引：0，他引：1  

王海霞  张宏升  李云峰  白敬蒋  潘江勇 《气象》2013,39(11):1500-1506

风廓线雷达资料具有较高的时间和空间分辨率,但多集中于强对流性天气的预报和分析。文章主要将该资料应用于低层大气风场结构的研究和分析中。利用2009年1月至2010年6月共计18个月的上海浦东国际机场LAP 3000边界层风廓线雷达探测的水平风速风向资料,根据差值后的每小时平均的风速、风向进行统计分析（垂直分辨率50 m）,发现风速极大值出现的高度具有重复性,主要出现在1000、600、500、450、550和250 m,相邻两层之间的风矢量变差的极大值主要出现在250和300 m之间。按照国际民航组织建议的的水平风的垂直切变强度标准,将各个层次之间的风矢量进行统计分类,有轻度、中度、强烈、严重四个等级的风切变,同时发现不同等级的风切变的发生具有明显的季节特征。对于浦东国际机场区域的低层垂直风场的特征及演变情况初步的分析和探讨,为今后可以更好地结合AMDAR资料、电子探空仪、微波辐射计等探测手段针对机场区域甚至是内陆部分机场关于风切变的精细化预报、预警服务的研究奠定了一定的基础。  相似文献   

Influence of Intermittent Turbulence on Air Pollution and Its Dispersion in Winter 2016/2017 over Beijing,China     

Wei  Wei  Zhang  Hongsheng  Cai  Xuhui  Song  Yu  Bian  Yuxuan  Xiao  Kaitao  Zhang  He 《Acta Meteorologica Sinica》2020,34(1):176-188

Journal of Meteorological Research - With rapid urbanization in recent years, severe air pollution has emerged as a major issue for many regions of China, especially in some metropolises. A...  相似文献   

新型铰接式重力锚的设计及其性能研究     

闫宏生  高率群  孟祥伟  李怀亮  于文太  刘建成 《海洋工程》2022,40(6):21-30

重力锚锚固是一种常见的锚固形式。为了能够提供足够的水平承载力,传统型式的重力锚普遍比较笨重,在上拔回收时会产生较大的竖向吸附力,不利于重复利用。针对此问题,设计了一种新型铰接式重力锚,并阐述了其铺设与回收方案。其次采用有限元方法对其整体强度进行了校核,结果均符合规范。最后基于模型试验,对铰接式重力锚在黏土中的运动过程进行了研究,进而确定了其在黏土中的水平承载力和回收时的上拔力。结果表明：相较于传统重力锚,新型铰接式重力锚在确保水平承载性能的基础上,能够大幅减小上拔力,从而有效地降低铺设和回收作业的难度,且可适应多种海底土质,但该锚型仅适用于悬链线式系泊系统。相关研究结果可为实际工程中铰接式重力锚的设计提供参考。  相似文献   

纤维加筋市政污泥剪切强度试验研究          下载免费PDF全文

王宏胜  王鹏  唐朝生  刘昌黎  施斌 《高校地质学报》2018,24(4):613

随着社会经济的快速发展,市政污泥产量逐年攀升,其安全处置对改善城市生态环境和经济可持续发展具有重要意 义。污泥由于含水率高,颗粒细小,粘滞性强,且富含有机质,因而存在机械脱水效率低和抗剪强度低等问题,填埋时容 易造成填埋场堆体发生侧滑、失稳等事故。纤维加筋是近些年发展起来的一种土质改良技术,为了研究该技术对污泥剪切 强度特性的影响,在不同固结压力下（50,100,200和400 kPa） 对纤维加筋污泥进行了一系列剪切试验,分析了纤维掺量 （0,0.05%,0.1%,0.2%,0.4%和0.8%） 对固结后污泥含水率、干密度及剪切强度的影响。结果表明：在不同固结压力 下,污泥排水固结后的含水率均随着纤维掺量的增加呈先减少后增加的趋势,而干密度则是先增加后减小,试验确定纤维 最优掺量为0.1%;污泥排水固结后的剪切强度则随着纤维掺量的增加而增加,纤维加筋作用对污泥的剪切强度提升效果十 分明显,100 kPa下加筋效果最显著;纤维加筋污泥的黏聚力和内摩擦角随纤维掺量的增加而增加,当纤维掺量超过0.4% 后,黏聚力增幅有放缓趋势,而内摩擦角的增幅则有加大趋势;在剪切破坏过程后期,随纤维掺量增加,应变硬化趋势更 为显著。  相似文献