夯扩桩成桩过程引起的挤土效应分析

夯扩桩在成桩过程中会产生挤土效应。通过采用柱形孔扩张理论，推导出砂土中形成扩大头时引起的挤土影响半径和土体位移，并对一工程实例进行了分析。     

Thermal surface characteristics of coal fires 1 results of in-situ measurements

Natural underground coal fires are fires in coal seams occurring subsurface. The fires are ignited through a process named spontaneous combustion, which occurs based on a natural reaction but is usually triggered through human interaction. Coal mining activities expose coal to the air. This leads to the exothermal oxidation of the carbon in the coal with the air's oxygen to CO₂ and – under certain circumstances – to spontaneous combustion. Coal fires occur in many countries world wide – however, currently the Chinese coal mining industry faces the biggest problems with coal fires. Coal fires destroy the valuable resource coal and furthermore lead to many environmental degradation phenomena such as the deterioration of surrounding vegetation, land subsidence and the emission of toxic gasses (CO, N₂O). They additionally contribute to the emission of green house relevant gasses such as CO₂ and CH₄ to the atmosphere.In this paper we present thermal characteristics of coal fires as measured in-situ during a field campaign to the Wuda coal fire area in south-central Inner Mongolia, China. Thermal characteristics include temperature anomaly measurements at the surface, spatial surface temperature profiles of fire areas and unaffected background areas, diurnal temperature profiles, and temperature measurements inside of coal fire induced cracks in the overlying bedrock. For all the measurements the effects of uneven solar heating through influences of slope and aspect are considered.Our findings show that coal fires result in strong or subtle thermal surface anomalies. Especially the latter can easily be influenced by heating of the surrounding background material through solar influences. Temperature variation of background rocks with different albedo, slope, aspect or vegetation cover can substantially influence the detectability of thermal anomalies. In the worst case coal fire related thermal anomalies can be completely masked by solar patterns during the daytime. Thus, night-time analysis is the most suitable for thermal anomaly mapping of underground coal fires, although this is not always feasible. The heat of underground coal fires only progresses very slowly through conduction in the rock material. Anomalies of coal fires completely covered by solid unfractured bedrock are very weak and were only measured during the night. The thermal pattern of underground coal fires manifested on the surface during the daytime is thus the pattern of cracks and vents, which occur due to the volume loss underground and which support radiation and convective energy transport of hot gasses. Inside coal fire temperatures can hardly be measured and can only be recorded if the glowing coal is exposed through a wider crack in the overlaying bedrock. Direct coal fire temperatures measured ranged between 233 °C and 854 °C. The results presented can substantially support the planning of thermal mapping campaigns, analyses of coal fire thermal anomalies in remotely sensed data, and can provide initial and boundary conditions for coal fire related numerical modeling.In a second paper named “Thermal Characteristics of Coal Fires 2: results of measurements on simulated coal fires” [Zhang J., Kuenzer C., Tetzlaff A., Oettl D., Zhukov B., Wagner W., 2007. Thermal Characteristics of Coal Fires 2: Result of measurements on simulated coal fires. Accepted for publication at Journal of Applied Geophysics. doi:10.1016/j.jappgeo.2007.08.003] we report about thermal characteristics of simulated coal fires simulated under simplified conditions. The simulated set up allowed us to measure even more parameters under undisturbed conditions — especially inside fire temperatures. Furthermore we could demonstrate the differences between open surface coal fires and covered underground coal fires. Thermal signals of coal fires in near range thermal remotely sensed imagery from an observing tower and from an airplane are presented and discussed.     

1999年8月11日日全食期间的重力吸引效应研究

对1999年8月11日日全食阴影扫过欧洲期间,设在Annelles,Uccle,Walferdange和Bondy弹簧和超导重力仪的记录进行了分析.为了确定月亮对太阳万有引力可能的遮挡效应的极限,对超导和弹簧重力仪记录进行了比较.同时也对LCR和阿斯卡尼亚重力仪观测结果进行了讨论.结论是如果日食重力吸引效应存在,它应在超导重力仪±1 nm/s2(0.1×10-8ms-2)的观测精度范围之内.研究发现在以上情形下,弹簧和超导重力仪都在它们的精度范围内工作,并且日食引起的异常环境干扰可能使重力信号有重大的改变.     

体感温度客观分析方法研究

影响人体体感温度的气象要素主要包括温度、湿度、风以及太阳辐射,依据这些气象要素影响人体体感温度的原理,确定了平均气温与体感温度相同时的临界相对湿度、风速及太阳辐射值.以全国有水平面直接辐射曝辐量观测项目的77个气象台站的历年逐日4次定时观测资料为基础,把相邻两个白昼(夜间)的气温差作为因变量,相对湿度差、风速差、垂直辐射差(白昼)作为自变量,以旬为时问分辨率,建立了逐旬多元回归方程.各地所建立的逐句多元线性拟合方程拟合优度相当高,F统计量检验也充分证明线性回归方程总体成立,从气候意义、统计角度来看该方法都具有充分的可行性.     

BDS卫星差分码偏差稳定性分析及其短期预报

利用MGEX(multi-GNSS experiment)发布的BDS卫星差分码偏差(differential code bias, DCB)产品，比较分析不同太阳活动水平下BDS卫星DCB产品的稳定性变化特性，并采用差分自回归移动平均(auto-regressive integrated moving average, ARIMA)时间序列预测模型，实现不同太阳活动水平下BDS卫星DCB的短期预报。结果表明，在太阳活动高年，BDS卫星DCB日解值稳定度、月稳定性均明显低于太阳活动低年，且不同卫星星座类型的BDS卫星DCB稳定性也存在差异；ARIMA时间序列预报结果与MGEX发布值符合程度较好，优于多项式拟合法预测结果。     

基于QuikSCAT卫星遥感风场的台风最大风速半径反演及个例分析

建立了一种卫星遥感风场的最大风速半径(Rmax )反演方法.该方法基于 QuikSCAT 风场,结合 JTWC 台风参数资料,将遥感平均风剖面与 Holland 台风模型进行最小二乘法拟合来反演 Rmax.2001-2009年13个台风69幅数据反演结果统计分析表明:用气压表征台风强度的 P 算法遥感反演结果与 JTWC 分析结果的标准差为10.7 km,效果较好.此外,通过0513、0519和0221 3个典型台风过程的 Rmax 演变情况分析表明:对于对称性结构较好的成熟台风,反演结果能较好地反映出不同台风的 Rmax 尺寸差别,台风过程中 Rmax 的演变情况符合台风发展情况;台风风场对称性差、地形以及背景流场的影响,是导致 Rmax 反演出现较大偏差主要因素.     

虚拟太阳天文台及其发展

伴随着太阳物理研究的深入、观测仪器的发展、观测数据的积累,促使人们去思考这样一个问题:如何使研究者能够方便地检索、分析和使用在不同时间、不同地点、不同波段上观测得到的大量与太阳有关的数据,从而能探索更多悬而未决的科学谜题。这就是虚拟太阳天文台(VSO)项目被提出后得到有关天文台、研究所和大学积极响应并迅速投入运作的原因所在。介绍了虚拟太阳天文台的由来、作用、采用的技术和发展状况等。     

实时相关跟踪图像处理系统

文章介绍了怀柔太阳观测基地最近完成的一套实时高分辨太阳磁场观测系统。系统采用局部相关跟踪算法来提高磁场观测数据的空间分辨率，同时对相关跟踪算法的实现程序进行了优化以满足常规太阳磁场观测的要求。通过对试观测和常规观测数据的分析，我们发现：1）该系统能够大大提高单色像、磁场数据的对比度和空间分辨率；2）对相关跟踪算法的优化大大提高了系统的时间分辨率，系统可以投入常规观测使用。     

西北地区太阳辐射量变化的研究

根据西北地区１５个日射甲种站观测的近３０年来到达地面的太阳辐射量观测资料，经方差分析表明：太阳散射辐射量有２／５的地区在增加，２／５的地区在减少，还有１／５的地区太阳散射、直接辐射量在时间变化上差异都不明显；太阳直接辐射量有４／５的地区在显著减减少；太阳总辐射量几乎各地都在减少，这种减少趋势大致从１９７８年开始，并且用太阳辐射倾向率的形式概括出３种太阳辐射量季节变化类型。