中国西北干旱区小冰期的湿度变化特征

选取中国西北干旱区11 条具有明确古湿度指示意义的气候记录, 结合冰芯、地层沉积、 湖泊沉积、树木年轮、河流阶地等各种研究资料和历史记载, 研究中国西北干旱区小冰期的湿 度变化。结果表明研究区小冰期(1400-1920 AD) 从整体而言处于相对湿润的阶段: 区内高大 山系降水处于较高时段- -西昆仑山古里雅冰芯积累量增大, 天山山间湖泊水位回升, 祁连山 敦德冰芯孢粉总浓度增加; 而盆地内流系统水量也出现了相应的变化- -塔里木盆地克里雅 河和塔里木河流量增大, 准噶尔盆地艾比湖水位上升, 巴丹吉林沙漠地下水补给量上升, 居延 海入湖水量增大, 湖面扩展, 青海湖盆地降水增加, 有效湿度增大, 苏干湖水体盐度降低, 入湖 水量/ 蒸发量之比升高。同时, 较高分辨率的湿度资料显示, 研究区东-南边缘地带在小冰期 内部存在次一级的干湿波动, 两个湿度较高的时期出现在16 世纪和18 世纪, 分别与小冰期内 部的两个相对温暖时期有很好的对应。中国西北相对湿润的小冰期主要是西风带强度增加和 位置南移造成该区域降水增多和全球性普遍降温导致有效湿度增大两个因素共同作用的结果, 研究区边缘地带小冰期内部冷干暖湿的配置则主要体现了夏季风的影响。     

Climate Change and Silk Road Civilization Evolution in Arid Central Asia: Progress and Issues

Arid central Asia is one of the regions most sensitive to global climate change, as well as the region with dramatically hydrological changes and fragile ecosystems. The region includes the main body of the ancient Silk Road, which played a key role in the cultural exchange and the rise and fall of Silk Road civilization. Scientific assessment of the risks faced by the sustainable development of human society in the arid central Asia under the background of global warming is a major scientific issue that has received much attention. The study of the relationship between cultural exchange, development of Silk Road civilization and climate change can provide a scientific basis for understanding the evolution rules of human-land relationship on different timescales in this area. This study summarized the research progress in the history of cultural exchanges, the rise and fall of Silk Road civilization, climate change during the Holocene, forcing mechanisms of climate and hydrological change on different timescales, as well as the process and rule of human-environment interaction. On this basis, we proposed that the study of the temporal and spatial patterns of Holocene climate change and the evolution of Silk Road civilization in arid central Asia, as well as the research on the interaction mechanisms between human and environment, are obviously insufficient. Solving the problems of regional imbalance of climate change and cultural evolution in arid central Asia and strengthening the cross-disciplinary study of geoscience and archaeology are effective ways to promote the study of climate change and changes of Silk Road civilization, which has important scientific and practical significance for understanding the evolution of human-land relations in the region, coping with the challenges of climate change, and serving the “One Belt, One Road” strategy.     

松南西斜坡前缘带青山口组层序界面识别及特征研究

在前人研究的基础上,应用高分辨层序地层学理论与研究方法,对松辽盆地南部西斜坡地区的青山口组地层进行了层序地层划分与对比工作,从中识别出6个具等时意义的层序界面,将其划分为5个中期基准面旋回(4级层序)。建立了层序界面的岩心识别标志,即旋回叠加样式的变化面、岩性突变面—冲刷面、相类型的变化面和暴露剥蚀面,在测井曲线上,层序界面位于测井曲线幅度发生明显变化或曲线组合型式的转换处,在研究区地震剖面上的层序界面识别标志(超削反射终止特征)不明显。根据层序划分和层序界面的识别标志,把4级层序界面划分为不整合面、沉积作用转换面和顶超面,并对层序界面特征进行了详细研究。确定了研究层段湖泛面包括三角洲体系—湖泛面、深水湖—浊积体系—湖泛面和河流体系—洪泛面3种类型。层序界面和湖泛面的识别和确定,对于研究区高分辨率层序地层格架的建立和对储层分布规律的研究与预测具有重要意义。     

多层结构MTMD振动控制系统参数优化研究

采用振动控制算法中的线性二次型最优控制,研究了在地震作用下的结构控制作用系统参数优化设计,即假定控制器数量、位置,对控制作用参数进行优化.将选取的主结构简化为多自由度模型,将MTMD(多重调谐质量阻尼器)对结构的反力与地震荷载共同作为结构的荷载输入分析;基于对主结构多模态耦合作用的考虑以及MTMD加载位置的初步假定,以二次型性能指标对系统状态方程加以控制.得到控制效果与利用最优参数法的结构控制效果做进一步比较验证.最后利用ANSYS优化设计模块,对已得到的控制器参数进行二次优化.     

基于北斗三号的大气水汽探测性能初步分析

对我国刚布署完成的北斗三号卫星导航系统(BDS-3)的大气水汽探测性能作初步分析可更好地发挥BDS-3的气象探测潜能.采用全球不同位置的台站进行几种手段的对比,探测结果具有代表性和说服力.研究结果表明:将BDS-3/PWV(大气可降水量)与GPS/PWV对比,平均偏差(BIAS)优于1.0 mm,均方根误差(RMSE)...     

渤海湾盆地济阳坳陷热历史及构造—热演化特征

根据镜质组反射率和磷灰石裂变径迹古温标方法模拟的济阳坳陷地温演化情况表明,地温梯度在坳陷的演化过程中是逐渐降低的。在孔店组-沙河街组沉积期间地温梯度是较高的,最高可达5.5～6.0℃/100m,但在此期间地温梯度下降较快,在东营组沉积时期降为3.5～4.5℃/100m;在馆陶组沉积时期地温梯度变化很小,至第三纪末地温梯度已降至目前的3.5℃/100m左右。济阳坳陷的构造沉降特征表现为孔店组至沙四段沉积期间(65～43Ma)的快速构造沉降阶段和沙三段沉积(43Ma)以后的热沉降阶段,盆地的地热史模拟结果和构造沉降所揭示的坳陷演化阶段具有很好的对应关系。坳陷热历史研究为渤海湾盆地的构造-热演化提供了重要的认识。     

无支护基坑侧移空间效应分析

针对基坑变形存在的空间效应,运用有限元分析软件ANSYS,对无支护结构情况下的基坑开挖过程进行数值模拟,分析了随开挖过程基坑壁侧向位移在水平和深度方向的分布规律,针对基坑坑角变化对基坑位移的影响进行了探讨,并对基坑壁位移的分布函数进行了讨论,得出一些有益的结论,为基坑工程设计与施工提供参考。     

禹城地区光合有效辐射的计算方法

利用2005年7月-2006年10月在山东禹城对太阳辐射（包括光合有效辐射PAR、可见光辐射VIS、总辐射Q等）、气象要素等进行的4次综合观测资料,初步得到了朋R,VIS的日、季节变化特征并对其进行了分析,结果表明：各辐射的小时累计之比vIS／Q,PAR／Q,PAR／VIS相对稳定,其平均值分别为0．39,1．95（mol／MJ）,4．97（mol／MJ）,但它们均有明显的日、逐日、季节变化,并受水汽、气溶胶、云等因素的影响。同时建立了实际天气PAR,VIS的小时累计经验公式及其转换关系,计算值与观测值均比较接近。当考虑水汽和散射因子时,PAR,VIS的计算值与观测值的相对偏差分别为11．1％,10．6％。限于实际情况,可以只考虑水汽因子的作用来计算PAR和VIS的小时累计值,它们的相对偏差分别为13．3％,12．6％。水汽因子对于PAR,VIS的传输和计算具有重要作用。     

Tectonic setting of Cretaceous basins on the NE Tibetan Plateau: insights from the Jungong basin

Quantifying the Cenozoic growth of high topography in the Indo‐Asian collision zone remains challenging, due in part to significant shortening that occurred within Eurasia before collision. A growing body of evidence suggests that regions far removed from the suture zone experienced deformation before and during the early phases of Himalayan orogenesis. In the present‐day north‐eastern Tibetan Plateau, widespread deposits of Cretaceous sediment attest to significant basin formation; however, the tectonic setting of these basins remains enigmatic. We present a study of a regionally extensive network of sedimentary basins that are spatially associated with a system of SE‐vergent thrust faults and are now exposed in the high ranges of the north‐eastern corner of the Tibetan Plateau. We focus on a particularly well‐exposed basin, located ～20 km north of the Kunlun fault in the Anyemaqen Shan. The basin is filled by ～900 m of alluvial sediments that become finer‐grained away from the basin‐bounding fault. Additionally, beds in the proximal footwall of the basin‐bounding fault exhibit progressive, up‐section shallowing and several intraformational unconformities which can be traced into correlative conformities in the distal part of the basin. The observations show sediment accumulated in the basin during fault motion. Regional constraints on the timing of sediment deposition are provided by both fossil assemblages from the Early Cretaceous, and by K–Ar dating of volcanic rocks that floor and cross‐cut sedimentary fill. We argue that during the Cretaceous, the interior NE Tibetan Plateau experienced NW–SE contractional deformation similar to that documented throughout the Qinling–Dabie orogen to the east. The Songpan‐Ganzi terrane apparently marked the southern limit of this deformation, such that it may have been a relatively rigid block in the Tibetan lithosphere, separating regions experiencing deformation north of the convergent Tethyan margin from regions deforming inboard of the east Asian margin.     

The luminescence dating chronology of a deep core from Bosten Lake (NW China) in arid central Asia reveals lake evolution over the last 220 ka

The lacustrine deposits of lakes in arid central Asia (ACA) potentially record palaeoclimatic changes on orbital and suborbital time scales, but such changes are still poorly understood due to the lack of reliable chronologies. Bosten Lake, the largest freshwater inland lake in China, is located in the southern Tianshan Mountains in central ACA. A 51.6‐m‐deep lacustrine succession was retrieved from the lake and 30 samples from the succession were used for luminescence dating to establish a chronology based on multi‐grain quartz OSL and K‐feldspar post‐IR IRSL (pIRIR₂₉₀) dating. Quartz OSL ages were only used for samples from the upper part of the core. The K‐feldspar luminescence characteristics (dose recovery test, anomalous fading test, first IR stimulation temperature plateau test) are satisfactory and from the relationship amongst the quartz OSL, IR₅₀ and pIRIR₂₉₀ doses we infer that the feldspar signals are likely to be well bleached at deposition. Bacon age‐depth modelling was used to derive a chronology spanning the last c. 220 ka. The chronology, lithology and grain‐size proxy record indicate that Bosten Lake formed at least c. 220 ka ago and that lake levels fluctuated frequently thereafter. A stable deep lake occurred at c. 220, 210–180, c. 165, 70–60, 40–30 and 20–5 ka, while shallow levels occurred at c. 215, 180–165, 100–70, 60–40 and 30–20 ka. Bosten Lake levels decreased by at least ~29 m and possibly the lake even dried up between c. 160 and c. 100 ka. We suggest that the water‐level fluctuations in the lakes of ACA may not respond directly to climatic changes and may be affected by a number of complex factors.