Numerical study on S-wave transmission across a rough,filled discontinuity

This paper presents a numerical simulation of S-wave propagation across a rough, filled discontinuity using the universal distinct element code (UDEC). The ability of UDEC to simulate a stress wave across a smooth and planar discontinuity filled with an elastic material is validated through comparisons with analytical solutions. Next, the effect of the plastic deformation of the fill on the wave propagation is investigated. The model is extended to further study S-wave propagation across a filled discontinuity with rough interfaces, which is described using a sawtooth. The transmission coefficient defined by the energy is used to measure the wave attenuation. Finally, a parametric study is conducted to investigate the influences of the filled thickness, asperity angle, and incident amplitude on the transmission waves and transmission coefficients. The asperity angle and filled thickness together determine the transmitted waveform and transmission coefficient. The transmitted wave may be cut off when the incident wave amplitude exceeds a threshold value. The transmission coefficient decreases with a different trend with the incident wave amplitude increasing when the asperity angle varies. Compared with planar discontinuity, a filled discontinuity with rough interfaces is more sensitive to the amplitude of the incident wave. The causes of these phenomena are analyzed in detail. In addition, the deformation of the fill material is strongly related to the wave attenuation.     

Analyses of structure of planetary boundary layer in ice camp over Arctic ocean

The vertical structure of Planetary boundary layer over Arctic floating ice is presented by using about 50 atmospheric profiles and relevant data sounded at an ice station over Arctic Ocean from 22 August to 3 September,2003.It shows that the height of the convective boundary layer in day is greater than that of the stability boundary layer in night.The boundary layer can be described as vertical structures of stability,instability and multipling The interaction between relative warm and wet down draft air from up level and cool air of surface layer is significant,which causes stronger wind shear,temperature and humidity inversion with typical wind shear of 10 m/s/100 m,intensity of temperature inversion of 8 ℃/100 m.While the larger pack ice is broken by such process,new ice free area in the high latitudes of arctic ocean.The interactions between air/ice/water are enhanced.The fact helps to understanding characteristics of atmospheric boundary layer and its effect in Arctic floating ice region.     

The response of key ecosystem services to land use and climate change in Chongqing: Time,space, and altitude

Mountainous landscapes are particularly vulnerable and sensitive to climate change and human activities,and a clear understanding of how ecosystem services (ES) and their relationships continuously change over time,across space,and along altitude is therefore essential for ecosystem management.Chongqing,a typical mountainous region,was se-lected to assess the long-term changes in its key ES and their relationships.From 1992 to 2018,the temporal variation in water yield (WY) revealed that the maximum and minimum WYs occurred in 1998 and 2006,which coincided with El Ni(n)o-Southern Oscillation and se-vere drought events,respectively.Soil export (SE) and WY were consistent with precipitation,which reached their highest values in 1998.During this period,carbon storage (CS) and habitat quality (HQ) both decreased significantly.ES in Chongqing showed large variations in altitude.Generally,WY and SE decreased with increasing altitude,while CS and HQ in-creased.For spatial distribution,WY and SE showed positive trends in the west and negative trends in the east.In regard to CS and HQ,negative trends dominated the area.Persistent tradeoffs between WY and soil conservation (SC) were found at all altitude gradients.The strong synergies between CS and HQ were maintained over time.     

利用无人飞艇获取影像资料制作DOM实践——以山东省博兴县城区为例

利用低空无人驾驶飞艇获取1：1．25万比例尺数字影像资料,制作1：1000比例尺的正射影像,并对正射影像精度进行检查、统计、分析,总结出影响正射影像精度的主要原因,并提出有益于提高正射影像精度的建议。     

藏北羌塘中侏罗世沟鞭藻

在藏北羌塘盆地中生界烃源岩成烃母质研究的一块标本中 ,发现了丰富且保存良好的沟鞭藻化石 ,至少包括有 2 1个属、 3 2个种的组合。这个组合以旋沟藻型占统治 ,大量发育栉型孢囊 ( ctenidodinioid) ,尤以 Ctenidodinium combazii居首位 ,其次为 Ellipsoidictyum cinctum和L ithodinia 的种 ,还有 Ctenidodinium continuum,C.ornatum,Gongaulacysta jurassica,Systematophora penicillata,Tubotuberella dangeardii和 Valensiella ampulla等中侏罗世巴统期至卡洛期的常见分子参与。根据组合面貌和属种成分的已知地史分布 ,其时代可确定为巴统期( Bathonian)或可能延至早卡洛期 ( Callovian)。沉积环境为正常盐度的开阔海 ,与欧洲诸海域可以沟通。本文还对 3个重要种进行了系统描述     

1987—1988年夏季长城站地区的热力和动力特征

本文利用1987～1988年夏季我国首次南极长城站边界层气象观测实验资料,运用近地层大气通量的平均廓线理论计算方法,分析了该地区夏季的热状况特征,并与南极内陆的瑞穗站及我国青藏高原等地区的热状况进行了初步比较。在夏季,长城站地面相对于大气而言,仍为热源,地面主要以潜热输送的方式加热大气。夏季长城站的热状况特征与我国青藏高原东部地区进入雨季后的情况相近。     

上对流层/下平流层大气垂直结构研究进展

大气上对流层与下平流层区域是对流层与平流层之间的过渡区域,热带对流层顸确定了全球整个平流层的化学边界条件,该区域大气的垂直结构及变化对于平流层一对流层交换和上对流层/下平流层大气成分收支有重要影响;该区域也是大气动力、热力和大气成分结构发生巨大转换的区域,辐射过程、多尺度动力学过程、化学过程和微物理学过程等都起着同样重要的作用,对流层顶变化也是人类活动引起气候变化的一个敏感指示因子,因此关于对流层顶的研究(尤其是其精细结构和过程)重新唤起了人们的关注.针对对流层顶的各种定义(包括热力学、动力学和化学成分)以及它们相互之间的关系、对流层顶是一个面还是层以及对流层与平流层之间的转换特征、对流层顶强逆温层的特征及形成原因等基本科学问题,回顾了近年来的一些重要研究进展.     

Particle size distributions and organic-inorganic compositions of suspended particulate matters around the Bohai Strait

Laser in situ scattering and transmissometry(LISST) significantly improves our ability to assess particle size distribu-tion(PSD) in seawater, while wide-ranging measurements of the organic-inorganic compositions of suspended particulate matters(SPM) are still difficult by using traditional methods such as microscopy. In this study, PSD properties and SPM compositions around the Bohai Strait(China) were investigated based on the measurements by LISST in combination with hydro-biological parameters collected from a field survey in summer 2014. Four typical PSD shapes were found in the region, namely right-peak, left-peak, dou-ble-peak and negative-skew shapes. The double-peak and negative-skew shapes may interconvert into each other along with strong hydrodynamic variation. In the upper layer of the Bohai Sea, organic particles were in the majority, with inorganic particles rarely observed. In the bottom layer, SPM were the mixture of organic and inorganic matters. LISST provided valuable baseline information on size-resolved organic-inorganic compositions of SPM: the size of organic particles mainly ranged from 4 to 20 μm and 40 to 100 μm, while most SPM ranging from 20 to 40 μm were composed of inorganic sediment.     

南极臭氧洞期间中山站和昭和站大气臭氧的中期振荡特征

本文用１９９３和１９９４年７～１２月中山站及昭和站大气臭氧观测资料和１９９３年７～１２月中山站地面温度、气压及戴维斯站探空资料，对南极臭氧洞期间中山站和昭和站的中期振荡特征进行了研究。结果表明：准一周和准二周振荡是南极地区大气臭氧和各层次温压参数普遍存在的两种主振荡周期，且在不同年份其振荡强度也有所不同。在中山站和昭和站地区，１９９３年大气各参数的准二周振荡强度大于准一周振荡，准一周和准二周振荡都是由西向东传播的；而在１９９４年则除准一周振荡外未出现准二周振荡。在普里兹湾地区平流层中下部臭氧和等压面高度、温度准一周和准二周振荡的位相差很小，振荡是同时发生的。准一周和准二周振荡都可以由上而下或由下而上地穿越对流层顶，平流层和对流层的中期振荡有着密切的关系。准二周振荡是大气中普遍存在的一种天气尺度的中期振荡，在不同地区可以对应不同的天气实体。在南极地区，大气臭氧总量的准二周振荡可能是极涡本身固有振荡的反映，而周期较短的准一周振荡则可能是外来扰动强迫振荡的反映。     

Detection of a primitive hydrogen cloud

Our identification of absorption systems in the quasars OQ 172, [4,6], has reliably determined one such at z = 3.3528 supported by the hydrogen lines L-L. Analysis shows it to be a primitive hydrogen cloud formed after the big bang. Assuming no broadening due to damping, we found a Doppler width b = 55 km/s and a column density 1g N_H = 14.66 from the curve of growth.