金州断裂降震效应初探

利用位于金州断裂两侧地震台所记录的地震震级的差异,研究金州断裂的降震效应。统计表明,当地震波通过断裂时存在明显的衰减现象,震级相差近０．４级。     

黄山黟县双套自动观测站数据的质量评估

利用2011年2月安徽省黄山市黟县试点双套自动观测气象站(A站和B站)和黟县本站(Z站,自动站)的气象要素(气温、气压、风速、相对湿度、地温等)观测资料,进行了对比分析,并对自动气象站仪器换型后数据的连续性进行了全面的评估。评估的内容为:数据的完整性和差异性,其中,差异性通过均值、标准差、误差率、粗差率和一致率得到体现。评估的结果表明:1)双套自动站观测数据的可靠性较好,大多数要素接收率高达100%,B站湿度接收率较低,只有83.3%,是由于B站的相对湿度传感器故障造成的;2)双套站观测的多要素有较好的一致性,但AB、AZ的地温差值和AB的气压差值一致率较低,部分要素差值存在少量的奇异值;3)T-检验表明,双套自动站的观测数据与历史序列无显著差异,连续性很好;4)双套自动站可用于气象业务观测,但还要进行一定时间的并行运行,以便日后更好地对数据进行对比分析和订正。     

1994年华南暴雨期间夏季风的特征及其对水汽的输送

用拉格朗日方法计算等熵面上空气质点和物质的轨迹。分析指出１９９４年华南暴雨和夏季风异常有密切的关系,特别是东亚热带季风更是决定性的作用;用这种方法可以追踪水汤的源地及演变过程,分析气流对水汽的输送作用。     

基于模糊贴近度的SAR影像变化检测方法研究

经典的基于比算子的差异图构造方法,主要是针对单一像素进行运算,因此影像噪声对差异图有一定程度的影响.将模糊贴近度应用于差异图的构造过程中,利用经典算子和模糊贴近度分别构造差异图;然后对差异图进行双边滤波和灰度过渡区域提取,从而确定影像分割阈值,得到两期影像变化结果;最后采用相关的参数指标对结果进行分析评价.结果 表明,...     

房产测量中面积预测与实测差异分析研究

房产测量的面积测算中,由于房屋预测成果和实测成果的差异而引发的矛盾和纠纷时有发生.根据笔者所了解的情况,针对其中几个关键的主要问题,即房屋预测成果与实测成果的时效的定义、保温墙体的厚度的定义、共有公用部位的问题进行了比较详细的论证与分析、并针对这些问题,提出了一些解决办法与对措施的意见和建议.     

Using hyperspectral reflectance data to assess biocontrol damage of giant salvinia

Field hyperspectral reflectance data were studied at 50 wavebands (10-nm bandwidth) over the 400- to 900-nm spectral range to determine their potential for distinguishing among giant salvinia (Salvinia molesta Mitchell) plants subjected to four population levels of salvinia weevils (Cyrtobagous salviniae Calder and Sands) to develop feeding damage to the plants. The four populations included a control with no insects and those with low, medium and high insect populations. The plants were studied in two experiments on each of two dates: 14 October 2010 and 21 July 2011. Two procedures were used to determine the optimum bands for discriminating among treatments: least significant difference (LSD) and stepwise discriminant analysis. The LSD comparison test results for both October and July experiments showed that generally the best bands for separating among treatments occurred in the green (505–595 nm), red (605–635 nm), red-near-infrared (NIR; 695–745 nm) edge and NIR (755–895 nm) regions where three to four treatments could be distinguished. Stepwise discriminant analysis identified four bands in the green, red and red-NIR edge to be significant to discriminate among the four treatments in Experiment 1 in October. For Experiment 2 in October, discriminant analysis identified five bands in the blue, green, red and NIR regions to be significant for distinguishing among the treatments. In Experiment 1 in July, five bands in the blue, green, red-NIR edge and NIR regions were found to be significant to discriminate among the treatments. For Experiment 2 in July, discriminant analysis identified four bands in the blue, green and red-NIR edge regions to be significant to discriminate among the treatments.     

Urban flood hazard mapping using change detection on wetness transformed images

ABSTRACT

The present study demonstrates the use of a new approach for delineating the accurate flood hazard footprint in the urban regions. The methodology involves transformation of Landsat Thematic Mapper (TM) imagery to a three-dimensional feature space, i.e. brightness, wetness and greenness, then a change detection technique is used to identify the areas affected by the flood. Efficient thresholding of the normalized difference image generated during change detection has shown promising results in identifying the flood extents which include standing water due to flood, sediment-laden water and wetness caused by the flood. Prior to wetness transformations, dark object subtraction has been used in lower wavelengths to avoid errors due to scattering in urban areas. The study shows promising results in eliminating most of the problems associated with urban flooding, such as misclassification due to presence of asphalt, scattering in lower wavelengths and delineating mud surges. The present methodology was tested on the 2010 Memphis flood event and validated on Queensland floods in 2011. The comparative analysis was carried out with the widely-used technique of delineating flood extents using thresholding of near infrared imagery. The comparison demonstrated that the present approach is more robust towards the error of omission in flood mapping. Moreover, the present approach involves less manual effort and is simpler to use.

Editor Z.W. Kundzewicz; Associate editor A. Viglione     

PUBLICATIONS OF THE INTERNATIONAL ASSOCIATION OF HYDROLOGICAL SCIENCES

Abstract

Explicit algebraic expressions of influence coefficients of an aquifer system are addressed. The methodology is straightforwardly exemplified using a one-dimensional (1D) semi-confined homogeneous aquifer model. It consists of the integration of the governing equation from two different viewpoints. On the one hand, the analytical solution to the governing equation is presented under an integral form involving the appropriate Green function. On the other hand, equations resulting from a finite difference discretization are processed to deduce a fully explicit algebraic expression of the nodal hydraulic head. This latter, arranged after the previously developed continuum solution, helps with deriving an explicit algebraic expression of influence coefficients corresponding to the studied aquifer model. Finally, the study is extended to an inhomogeneous aquifer model.     

基于DTOA/DOA和牛顿迭代法的震源定位方法研究

结合DTOA和DOA联合定位估计性好与牛顿迭代法收敛速度快的优点,提出了一种基于DTOA和DOA初值选取和牛顿法精确迭代的震源定位方法.经过野外实验和仿真,发现该方法能有效地提高震源定位的准确性.通过对影响震源定位精度因素分析,表明减小传感器基站站盐和初至波到时差测量误差可有效提高定位精度,相同同条件下,星型布站的定位精度最高.     

采用sPn震相确定甘肃岷县M>4.0地震震源深度

通过对甘肃岷县2013年7月3个M>4.0地震震相的细致分析,认为在震中距大于250km时四川数字地震台网部分台站可记录到较为清晰的sPn震相。采用sPn和Pn震相确定震源深度的方法分别对岷县3个地震的震源深度进行了重新计算,得到了较为精确的地震震源深度。