太湖水体的总磷分布及湖流对其影响的数值研究

用数值模拟的方法研究了太湖水体中ＴＰ分布特征及湖流对其影响,推导,建立了包括平流,水平扩散,沉降和底泥释放的浅水湖泊中污染物浓度分布计算的二维迎风有限元数值模式,并在给定若干点源条件下计算各种稳态流场下太湖水体中的ＴＰ分布。     

降雨对张家口地震台伸缩仪干扰特征的研究

张家口伸缩仅受降雨干扰，不但与降雨量有关，而且与季节和降雨的方式等也有密切的关系。夏、秋季节持续或突降大雨后，两天左右引起应变量明显的变化，可用2．5倍毫米应变均方差，识别干扰和异常，有较大的使用价值。     

特大地震对震源邻区的增(减)震作用的研究

通过研究中国大陆1910年以来8级以上特大地震和国外几组典型特大地震对震源邻近区域的影响,发现特大地震往往发生在断裂带上,一组或一次特大地震可能使发震断裂部分破裂,而未破裂断裂的构造应力可能增大,又成为大震的空段,该空段短时间内可能会发生大震(起到增震作用);反之,发震断裂完全破裂或没有大震空段,震源邻近区域构造应力可能减小,短时间可能不会发生大震(起到减震作用)。依据这一结果,可对特大地震发生后震源邻近区域的后续大震作短、中期预测。     

板内与板间地震活动时空分布的多重分形特征研究

利用多重分形分析方法,考察了中国大陆和台湾地区以及新西兰的地震活动广义应变释放时间和空间分布的多重分形特征. 结果表明,地震活动时空分布的多重分形特征与不同地球动力学环境关系密切. 强震活动时间分布在板间地区具有比板内地区更明显的丛集性, 对中小地震这种丛集性差异较小;强震活动空间分布在板内地区具有比板间地区更强的丛集性,但对中小地震则相反.      

数字化水位仪漏电干扰因素的分析与排除

主要针对数字化水位仪在运行过程中产生的漏电干扰进行了分析,并结合实际情况提出了具体有效的解决方案.     

应用线性合成概率方法探讨青藏高原北部地区强震趋势

基于周期谱分析基础上的线性合成概率预测方法,对青藏高原北部地区Ms≥7.0、Ms≥6.5强震进行了试验性研究,并利用其结果作为预测依据,对青藏高原北部地区强震趋势做了初步估计.利用该方法,本文还对东昆仑断裂带1900年以来的Ms≥7.0强震进行了研究.     

The Kuroshio Extension: a leading mechanism for the seasonal sea-level variability along the west coast of Japan

Sea level changes coherently along the two coasts of Japan on the seasonal timescale. Archiving, validation, and interpretation of satellite oceanographic altimetry data and ocean general circulation model for the Earth Simulator results indicate that the variation propagates clockwise from Japan’s east coast through the Tsushima Strait into the Japan/East Sea (JES) and then northward along the west coast. In this study, we hypothesize and test numerically that the sea-level variability along the west coast of Japan is remotely forced by the Kuroshio Extension (KE) off the east coast. Topographic Rossby waves and boundary Kelvin waves facilitate the connection. Our 3D Princeton Ocean Model when forced by observed wind stress reproduces well the seasonal changes in the vicinity of JES. Two additional experiments were conducted to examine the relative roles of remote forcing and local forcing. The sea-level variability inside the JES was dramatically reduced when the Tsushima Strait is blocked in one experiment. The removal of the local forcing, in another experiment, has little effect on the JES variability. Both experiments support our hypothesis that the open-ocean forcing, possibly through the KE variability, is the leading forcing mechanism for sea-level change along the west coast of Japan.     

Characteristics of Seismic Activity in a 3-Dimensional Space before the Wen'an Earthquake,Hebei Province by Relocation of Small Earthquakes in the China's Capital Area

Characteristics of seismic activity before the M5.1 earthquake in Wen'an,Hebei Province on July 4,2006 are analyzed by relocation of small earthquakes in the China's capital area,and some results are obtained as follows:① The seismic activity of M L ≥3.0 in the middle part of the Hebei plain seismic belt displayed a feature of strengthening (lasting 43 months) quiescence (17 months) five years before the Wen'an earthquake.Simultaneously,the strain release curve showed a variation process of accelerating-flatting.② A seismogenic gap in a three-dimensional space,located at the depth of 15km ～ 20km,with 70km long in latitude direction and 90km long in longitude orientation,was formed by M≥2.0 earthquakes four years prior to the Wen'an earthquake.The initial rupture point of the Wen'an earthquake is situated at the bottom of the gap.③ The focal depths of earthquakes with M L ≥2.0 in the middle part of the Hebei plain seismic belt gradually increased from 10km to 30km during the period from April,2003 to October,2004.Meanwhile,the seismic activity obviously strengthened in the middle and lower crust (from 20km to 30km in depth).     

Effectiveness of grass strips in trapping suspended sediments from runoff

Little information is available concerning the performance of grass strips for erosion control from steep cropland. An experiment was conducted on 5‐m‐long grass strips with slopes of 3°～15° that were subjected to silt laden runoff and simulated rainfall, to investigate the sediment trapping processes. The grass strips had three treatments including intact grass control (C), no litter (dead grass material covering the soil surface was removed) (NL), and no litter or leaves (only 2～3 cm grass stems and roots were reserved) (NLL). Generally the grass strips had a high effectiveness in trapping sediment from steep cropland runoff. Sediment trapping efficiency (STE) decreased with increasing slope gradient, and even for a 15° slope, STE was still more than 40%. Most sediment deposited in the backwater region before each grass strips. The removal of grass litter or/and leaves had no significant influence on STE. The sediment median size (D₅₀) in inflow was greater than that in outflow, and the difference (ΔD₅₀) decreased with increasing slope. A positive power relationship between STE and ΔD₅₀ can be obtained. Grass strips were more effective in trapping sediments coarser than 10 or 25 µm, but sediments finer than 1 µm were more readily removed from runoff than particles in the range of 2 to approximately 10 µm. Grass litter had less influence on flow velocity than leaves because the deposited sediment partially covered the litter layer. Mean flow velocity and its standard deviation were negatively correlated with STE, and they can help make good estimation of STE. Results from this study should be useful in planting and managing forage grass to effectively conserve soil loss by runoff from steep slopes on the Loess Plateau of China. Copyright © 2010 John Wiley & Sons, Ltd.