Scattering and absorption coefficients of aerosols in a semi-arid area in China: Diurnal cycle, seasonal variability and dust events

The authors investigated variations of aerosol scattering and absorptive properties in a semi-arid climate Observatory in the Inner Mongolia of China and factors affecting the variation. They use integrated nephelometer and aethalometer observations collected in 2005 and 2006 at the Silinhot Observatory. The results are as follows. 1) in autumn and winter, the diurnal cycle of scattering coefficient exhibited a clear bi-modal variation, and the scattering coefficient was indicative of the type of sandy weather. 2) The concentration of black carbon (BC) aerosols was much higher in winter than in the other seasons with an evident bimodal diurnal variation. 3) When the wind speed was lower than 3.5 m s^?1, the dilution effect of air evidently influenced the scattering coefficient and BC mass concentration; for the wind speed above 3.5 m s^?1, there appeared to be little correlation between wind speed and scattering coefficient or BC mass concentration. 4) Atmospheric visibility calculated from the aerosol scattering and absorptive coefficients was in good agreement with the direct observation of visibility. 5) Absorption by aerosols accounted for 25% of the total extinction in December.     

Evaluating the Impact of Optical Axis Stability on Exoplanet Detection

For detecting exoplanets with high precision,using the angular distance between the two stars to detect the periodic motion of the star will be a better choice....     

HSR mechanisms and effects on the spatial structure of regional tourism in China

Chinese railway has entered the “HSR era”, while the structure of “four vertical and four horizontal” railways for transit passengers is almost completed. Taking the Beijing- Shanghai High-Speed Rail (hereinafter referred to as HSR) as an example, this paper first explores HSR’s effects on the spatial structure of regional tourist flows using the social network analysis. Next, it notes changes in the accessibility of regional transportation. After analyzing the factors including initial endowment of regional tourism resources, hospitality facilities, the density of the regional tourism transportation network, and locations, the paper discusses the mechanisms through which HSR affects regional tourist flows. The study shows the following: (1) HSR’s effects on the spatial structure of regional tourist flows are manifested through the Matthew effect, the filtering effect, the diffusion effect and the overlying effect, and (2) the Matthew effect of HSR is manifested under an obvious interaction of the location, the initial endowment of tourism resources, hospitality capacity, tourist transportation network density and “time-space compression”. The filtering effect of HSR is manifested for those tourism nodes without favorable location conditions, endowment of tourism resources, hospitality capacity, or tourist transportation network density and without obvious benefits from “time-space compression”. Those tourism nodes that boast advantages in terms of location condition, endowment of tourism resources, hospitality capacity, tourist transportation network density and obvious “time-space compression” will become sources for the diffusion effect. HSR will strengthen the aggregation effects of tourist flow in these diffusion sources, which will thereafter diffuse to peripheral tourist areas, manifesting “aggregation-diffusion”. HSR has overlapped tourists’ spatial traveling range over large-scale spaces. However, the overlying effect is only generated in those tourism nodes with a favorable location condition, an endowment of tourism resources, hospitality capacity, tourist transportation network density, and obvious “time-space compression”.     

毛乌素沙地现代沙丘沙的粒度特征及其意义

对毛乌素沙地不同类型41个现代沙丘的沙粒度分析结果表明,流动沙丘沙主要由细沙和中沙组成,平均粒径为2.17 Φ;固定-半固定沙丘沙的主要粒级是细沙和极细沙,平均粒径为3.09 Φ。流动沙丘沙平均粒径整体自西北到东南减小,而分选性总体表现为中等-较好,无明显空间变化规律。概率累计曲线和粒度特征参数散点图表明,毛乌素沙地沙丘沙以跃移搬运方式为主,存在着就地起沙和就地堆积的可能。平均粒径和分选性空间变化规律的差异,是在频繁强烈的风沙活动环境下物源和大气环流共同作用的结果。     

Geo-stress Characteristics of Schist of Erdaoya Tunnel and Physical Properties of Rock Masses

Erdaoya tunnel in the highway connecting Shiyan (Hubei province) and Manchuan, (Shanxi province) was studied in the study. Various problems occurred in the construction of the tunnel, including large deformation of surrounding rocks, cracks of preliminary supports and secondary linings as well as creeping down and collapse of surrounding rock masses along schistosity planes. In which, the most serious problem was large deformation of surrounding rocks, which not only dramatically delayed the normal construction progress of the tunnel, but also brought a huge challenge for the safety of builders. In order to solve this problem, detailed investigations were made on site in the study to reveal the regional geological, engineering geological and hydrogeological conditions of the tunnel. By conducting geo-stress measurement on site, the characteristics of geo-stress field of Erdaoya tunnel were analyzed from four aspects, including magnitudes of stress, coefficient of lateral pressure, orientation of stress and the relationship between magnitudes of geo-stresses and depths. By applying the DIPS software for interactively analyzing geological locator data, structure characteristics of rock masses were analyzed for preferred structural planes and schistosity planes in the tunnel site. Furthermore, the authors tested the physical and hydrological properties of the rock specimens collected on-site. So various physical properties (density, void fraction, and wave velocity) and water absorption hydrological property of schist were obtained, which provide underlying parameters support for the deformation and support of surrounding rocks of the tunnel.     

The Large-Scale Shaking Table Model Test of the Shallow-Bias Tunnel with a Small Clear Distance

A physical shaking table test model of the shallow-bias tunnel with a small clear distance whose scale was 1:10 was performed to study the type, direction and acceleration peak of the seismic wave which have an immense influence on the dynamic response characteristics of the tunnel. In shaking table model test, the Wen Chuan wave (wc–xz), Da Rui wave (dr–xz) and Kobe wave (k–xz) were adopted as loading wave in x, z-direction (horizontal and vertical direction loading at the same time). The results show that under the action of seismic wave, the acceleration amplification factor of z-direction is generally larger than that of x-direction. Compared with the lining of the right hole, the acceleration amplification factor and variation trend of the lining of the left hole are highly different. The strain is less affected by the type of seismic wave, but that is greatly affected by acceleration peak. The tension strain increases with the increase of the acceleration peak of seismic wave, and is larger than the compression strain at each measuring point. The variation trend of tension strain is more intense than the compression strain.     

钻孔体应变与面应变观测井孔耦合系数的计算

钻孔应变观测系统（岩石、 膨胀水泥和应变仪钢筒）存在显著的井孔耦合效应,只有确定这一耦合系数,才能得到地壳岩石的真实应变值,从而实现不同测点数据的可比性．本文根据双衬套理论及弹性力学理论,建立了三维空间应力作用下体应变与面应变观测力学模型,并进一步推导各自井孔耦合系数计算式,发现两组系数与井孔的受力状况密切相关,分别与不同力源引起的应变信号相对应．亦即应力比（钻孔轴向应力与平面应力之比）不同,耦合系数也不一样,体应变随应力比的增大而下降,面应变则上升. 本文结果还表明平面应力作用下的耦合系数与外加应力无关,只与观测系统本身有关,故数值保持恒定. 此外,文中对其影响因素也进行了分析,结果表明,体应变和面应变的井孔耦合系数均随岩石弹性模量和泊松系数的增大而增大,且前者的幅度较大,井孔耦合材料水泥对二者影响均很小．      

一次台风外围雨带多普勒天气雷达回波及风场结构分析

使用常规天气资料、卫星云图和长春c波段多普勒雷达资料对2004年7月5日发生在吉林省的一次典型台风外围雨带降水天气过程进行了分析.可看出两种尺度云系的相互作用,整个降水雨带为明显的旋转西进过程.多普勒径向速度图上,低层辐合高层辐散的配置有利于降水的发生发展.另外,低层由于存在摩擦,受台风雨带影响较小,而中高层受台风中α尺度系统和中B尺度雨团的共同影响,两者风场的叠加造成低层偏东风到高层东北风的风向变化.可提高预报的准确率,为人工增雨决策提供可靠依据.