A Three-Point Method for Separating Incident and Reflected Waves over A Sloping Bed

This study presents a three-point method for separating incident and reflected waves to explain normally incident waves' propagating over a sloping bed. Linear wave shoaling is used to determine changes in wave amplitude and phase in response to variations of bathymetry. The wave reflection coefficient and incident amplitude are estimated from wave heights measured at three fixed wave gauges with unequal spacing. Sensitivity analysis demonstrates that the proposed method can predict the reflection and amplitude of waves over a sloping bed more accurately than the two-point method.     

再探温跃层有孔虫B/Ca与温度和[CO32-]的依赖性及其在24 ka以来热带西太平洋次表层碳酸盐系统重建中的应用

The B/Ca ratio of planktonic foraminifer shells has been used as a proxy for reconstructing past ocean carbonate chemistry. However, recent studies have revealed significant uncertainties associated with this proxy, such as whether seawater temperature or [ CO_3~(2-)] is the dominant control on the partition coefficient(K_D) of planktonic foraminiferal B/Ca. To address these uncertainties and thus improve our understanding of the planktonic foraminiferal B/Ca proxy, we analysed B/Ca ratios in the tests of Neogloboquadrina dutertrei(300–355 μm) and Pulleniatina obliquiloculata(355–400 μm) in surface sediment samples from the tropical western Pacific and South China Sea. The relationship between these B/Ca ratios and bottom water calcite saturation states(Δ[ CO_3~(2-)]) is weak, thus suggesting only a small dissolution effect on the B/Ca of the two species. The correlation coefficients(R~2) between the B/Ca ratios of N. dutertrei and P. obliquiloculata and environmental parameters(e.g., temperature, salinity, phosphate, DIC and ALK) in the tropical western Pacific and South China Sea are not high enough to justify using B/Ca ratios as a palaeoenvironmental proxy in the study areas. The significant correlation between K_D values of N. dutertrei and P. obliquiloculata and carbonate system parameters(e.g.,[ CO_3~(2-)], DIC, ALK, pH and [ HCO_3~-]) in the study area reflect chemical links between the K_D denominator and these variables. Based on our surface sediment calibration, an empirical relationship between the K_D of N.dutertrei and temperature is proposed in the tropical western Pacific. We also generated a record of B/Ca ratios in N. dutertrei(300–355 μm) from Core MD06-3052 in the tropical western Pacific over the past 24 ka to evaluate the application of the revised B/Ca proxy method. Based on the reconstructed empirical relationship for B/Ca and subsurface seawater ALK, we estimated subsurface seawater carbonate system parameters in the tropical western Pacific since 24 ka. In general, the estimated subsurface seawater pH and [ CO_3~(2-)] show an increase with time, and the record of subsurface seawater pCO_2 shows a decrease with time, in the tropical western Pacific over the past 24 ka. The consistent trends in subsurface seawater pCO_2 and opal flux during deglaciation may imply that the reported increase in subsurface water pCO_2 in the study area was promoted by enhanced upwelling in the Southern Ocean.     

雅鲁藏布江蛇绿岩中地幔柱型岩浆作用——来自氦、氩同位素的证据

雅鲁藏布江蛇绿岩的氦、氩同位素组成分别是：蛇绿岩中变质橄榄岩的^3He/^4He比值为1．104-3．384Ra,平均为2．383Ra;玄武岩的He同位素组成比较均一,^3He/^4He平均值为5．359 Ra;辉绿岩的^3He／^4He比值变化较大,为1—5Ra。由于各岩石样品有不同程度的蚀变,造成放射性成因He的加入,因此大多数样品He同位素组成比低于亏损地幔大洋中脊玄武岩的值(MORB≈8Ra),不能真实反映源区特征。而采自吉定的辉绿岩样品^3He/^4He比值平均高达31．57Ra,与夏威夷发现的热点地幔源区的样品比值接近;分步加热法进一步测试,其高比值的He是在低温区段释放的。这种高^3He/^4He比值He的捕获,表明雅鲁藏布江蛇绿岩形成时存在地幔柱型富集地幔岩浆作用。     

“9·5”泸定震后落井沟泥石流灾变过程预测分析

落井沟位于四川省泸定县得妥镇东南部,从沟口至其东南部约11 km处有正在运营的大岗山水电站。为有效防止落井沟泥石流对得妥人民的生命财产及大岗山水电站的运维造成的威胁与损毁,开展对泸定震后落井沟内物源分布特征与不同降雨周期下泥石流运动演化过程分析。“9·5”泸定地震后,耦合现场调查与地震前后遥感影像解译,得出强震致使落井沟流域内产生滑坡37处,总面积约0.125 km²,并采用LiDAR航拍技术优化解译结果,得到实际松散堆积物方量为15.52万m³。随后结合精准物源、精细化地形及5%、2%、1%降雨频率,开展基于OpenLISEM数值计算的落井沟泥石流运动演化特征研究。结果表明：5%、2%、1%降雨重现周期下落井沟泥石流运动过程的最大泥深分别为6、8、11 m,最大流速分别为5、7、10 m/s; 5%、2%降雨频率下泥石流对大渡河的堵江程度较小,1%频率下可造成半堵江状态。     

Determination of 3-D Velocity Anomalies of the Nanbei Tectonic Zone of China Based on Local Earthquakes

In this paper, 3-D velocity images of the crust and upper mantle beneath the Nanbei tectonic zone of China are constructed using P-wave travel time residuals of earthquakes, with the data supplied by China's seismic networks and the International Seismic Centre.During the model parameterization in the tomographic inversion the interpolation function of grid node velocities is used as the space function of velocity, and the velocity function is allowed to be discontinuous. The difficulties caused by large memory demand and high computing cost in solving the system of equations are avoided by utilizing the least squares QR decomposition algorithm. Thus, the stability of the algorithm is ensured. Though resolution images are not derived in the inversion process based on the resolution theory of Backus and Gilbert, a covariance resolution method is put forward by the authors. The resolution analyses have proved the reliability of the image results. 3-D ray tracing is conducted to obtain the ray paths in a s     

北斗高精度长弧历书模型设计

历书参数可同时用于辅助常规导航和自主导航的信号捕获。延长历书参数的有效期不但可以使地面接收机启动时充分利用历书数据,对于基于星间链路观测的自主导航,历书参数的有效期还决定了地面注入历书的频度和占用的星上存储资源。通过对北斗3类导航卫星主要摄动力及其对轨道根数的长期项和长周期项的影响分析,设计了以6个轨道根数和5个摄动参数为播发参数的历书拟合模型。以一个自主运行周期90 d为时间尺度,对北斗在轨卫星进行了长弧段历书拟合试验,并同时分析了卫星位置和速度的拟合精度。结果表明新的历书拟合模型提高了历书拟合的精度,尤其对于地球静止轨道和倾斜地球同步轨道卫星,拟合精度提高显著。对于GEO和IGSO卫星,位置拟合误差大约从200 km降低至十几千米甚至几千米,速度拟合误差大约从15 m/s降低至0.6 m/s,新方法拟合精度提高了约20~30倍;对于中圆地球轨道卫星,无论采用哪种历书模型,位置拟合误差都在5 km左右,速度拟合误差都在0.6 m/s左右,新方法拟合精度提高约15%。针对星间链路卫星10 km位置误差上限的使用需求,对比了新老历书模型的拟合弧长,常规模型最大拟合弧长约为14 d,而新历书模型的最大拟合弧长可延长至45 d,新历书模型延长了历书使用期限,优化了北斗历书模型设计。     

GPS系统硬件延迟估计方法及其在TEC计算中的应用

给出了用于估计GPS系统硬件延迟的卡尔曼滤波的状态方程和观测方程,在卫星和接收机相对硬件延迟计算方法的基础上,进一步给出了滤波器初值的计算方法,然后给出了GPS系统硬件延迟和卫星相对于平均值的硬件延迟的计算结果,并对GPS系统硬件延迟及卫星和接收机硬件延迟的稳定性进行了评价,结果表明,在两个半月的时间里,它们是非常稳定的,最后通过TEC的计算结果及其与滤波估计的比较证明了本文方法的正确性.     

ON THE DISCOVERY OF THE GRAPTOLITE-SHALE FROM LIENTAN,YüNAN DISTRICT IN KWANGTUNG PROVINCE AND ITS STRATIGRAPHIC CORRELATION

During the years of 1869-1870 von Richthofen~1 first studied the geologyof Kwangtung province.His journey was,however,only confined to atraverse route along the North River from Sanshui,Chüchiang to Hunan province.The geology of the West River districts was quite unknown to him,he did notgo so far to those districts.After von Richthofen,in the years of 1911-1916     

煤层气直井产气曲线特征及其与储层条件匹配性

煤层气产气曲线类型与地质条件的匹配与否直接影响产气效果。以沁水盆地柿庄南区块排采4 a以上的直井为研究对象,在产气曲线类型划分基础上,分析不同产气曲线特征,进一步分析产气曲线与储层参数的匹配性。结果表明：研究区产气曲线可划分为单峰快速上升、单峰稳定上升、双峰后低和双峰后高4种类型。产气曲线所表现出的特征受控于储层原始渗透率,储层动力及压裂效果。单峰快速上升型适用于含气量大于12 m³/d、临储比大于0.4和渗透率大于0.1×10^-3 μm²的储层,该种曲线容易造成产气量的骤降;单峰稳定上升型适用的储层条件广泛,与储层参数匹配性较高;双峰后低型产气效果整体不佳,与储层参数的匹配性差;双峰后高型适用于压裂效果较好的井、对储层原始参数要求较低,其后峰产气量的增加速率影响整体的排采效果。基于上述分析,将储层划分为七种类型,对研究区及其相邻区块实施\     

青藏高原那曲地区夏季一次对流云降水过程的云微物理及区域水分收支特征

第三次青藏高原科学试验针对高原夏季云和降水物理过程开展了大量观测研究,为进一步揭示高原云微物理结构、云中水分转化和区域水分收支特征,本文采用中尺度数值预报模式（WRF）并结合高原试验期间的各种观测资料,对那曲观测试验区2014年7月5~6日的一次较为典型的夏季对流云降水过程进行了数值模拟研究。结果表明WRF模式能够基本再现高原夏季对流云的发展演变过程以及降水的日变化特征。模拟结果显示高原夏季对流云中具有较高的过冷云水和霰粒子含量,冰相过程在高原云和降水的形成和发展中具有十分重要的作用,地面降水主要由霰粒子融化产生。暖雨过程对降水的直接贡献很小,但在霰胚形成中具有十分重要的作用。霰粒子胚胎的形成主要来源于冰晶与过冷雨滴的撞冻过程,雪粒子和过冷雨水的碰冻转化及过冷雨滴的均质冻结贡献相对较小。霰粒子的增长过程在12 km（-40℃）以上层主要依靠对冰晶、雪粒子的聚并收集过程,而在其下层的增长过程主要依赖对过冷云水的凇附增长,对雪粒子的聚并收集和凝华增长过程较小。高原那曲地区净水汽收支为正,日平均降水转化率可达20.75%,接近长江下游地区,高于华北、西北地区。该地区日降水再循环率为10.92%,说明局地蒸发的水汽对高原降水的水汽来源具有一定的贡献,但高原降水的90%仍然由外界输入的水汽转化形成。