基于模糊熵的GLLE熵阈值分割方法     

何春明  许磊  卢国胜  邓丽珍 《南京气象学院学报》2019,11(6):757-763

图像分割是计算机视觉中基础且重要的一个问题.熵阈值图像分割作为一种有效的分割方法,被广泛应用于模式识别和图像处理中.传统的图像分割方法并不能获得足够有效的图像特征.为解决这个问题且进一步探究熵阈值在图像分割中的应用,引入一种GLLE（Gray Level and Local Entropy）二维直方图改进熵阈值图像分割模型,并提出了基于模糊熵的方法计算所建立的二维直方图模型.通过标准实验数据集上的对比实验表明,基于模糊熵的GLLE熵阈值分割方法可以得到更加准确的阈值,提高了分割精度.同时在处理不同类型图像的表现上优于往常的算法,具有更强的鲁棒性.  相似文献   

Latitudinal and local variations of the life history characteristics of the thalassinidean decapod, Upogebia yokoyai: A hypothesis based on trophic conditions     

Miho Yamasaki  Takahiro Nanri  Shino Taguchi  Yoshitake Takada  Masayuki Saigusa 《Estuarine, Coastal and Shelf Science》2010

Mean total length of the eldest cohort (MTLe) of the thalassinidean decapod, Upogebia yokoyai sampled at 16 sites showed a latitudinal variation from south-west islands of the Ryukyu Archipelago (24° N) to the Seto-Inland Sea of Japan (34° N). Local variations were however also found from sites in the same latitudes. The level of the organic content in each habitat showed a positive correlation with MTLe. We hypothesized that MTLe is strongly affected by the trophic condition, resulting in the local variations. To test this hypothesis, two estuaries with different organic content were compared; Kodono River (Kochi Prefecture, 33° N) which was relatively oligotrophic and Sakata River (Hiroshima Prefecture, 34° N) which was highly eutrophicated. The Kodono River population showed slow growth after settlement, and growth stopped in May to June. This population survived for only one or two years, resulting in small MTLe. On the other hand, the Sakata River population showed fast growth from August to December. This population survived for three years, resulting in large MTLe. Maturation was estimated to occur two years after settlement in both populations. Low salinities may partially affect MTLe. Habitats in the Seto-Inland Sea (33.5–34.8° N) were eutrophicated, but many habitats in the subtropical islands (24–31° N) were relatively oligotrophic. Latitudinal variation of MTLe was reflected by the geographical difference in trophic condition. A negative relationship between population density and growth was found, which was explained in terms of reduced survival of recruits in the eutrophicated habitats.  相似文献   

Identifying effects of local and nonlocal factors of soil water storage using cyclical correlation analysis     

Asim Biswas  Bing Cheng Si 《水文研究》2012,26(24):3669-3677

There are various factors governing the spatial and temporal variability of soil water storage including soil properties, topography and vegetation. Some factors act locally, whereas others act nonlocally, which means that a factor measured at one location has effect on soil water storage at another location. The objective of this study was to examine the effects of local and nonlocal controls of soil water storage in a hummocky landscape using cyclical correlation analysis. Soil water storage, soil properties and terrain indices were measured along a 128‐point transect of 576 m long from the semiarid, hummocky, prairie pothole region of North America. There are large coefficients of determination (r²) between soil water storage and sand content (r² = 0.32–0.53), organic carbon content (r² = 0.22–0.56), depth to carbonate layer (r² = 0.13–0.63), wetness index (r² = 0.25–0.45) and other variables at the measurement scale at different times, indicating strong local effects from these variables. The correlation coefficients were also calculated by physically shifting the spatial series of soil water storage with respect to that of controlling factors. The shifting improves the correlation between the spatial series, and the length of shifting indicated the difference in the response of soil water to its controlling factors. For example, the value of r² increased more than eightfold (r² = 0.47–0.64) after shifting the spatial series of soil water storage by 54 m, almost equal to the average length of existing slope, compared with the very weak correlation (r² = 0.02–0.08) at the measurement scale. This indicated the nonlocal effect from the relative elevation. The identification of nonlocal effects from factors improves the prediction of soil water storage. Copyright © 2011 John Wiley & Sons, Ltd.  相似文献   

Comparison of ordinary and disjunctive kriging in an Indian iron ore deposit     

P. S. N. Murthy 《Mathematical Geology》1989,21(4):443-461

This paper presents the results of disjunctive kriging applied to a supergene iron ore deposit of Bailadila Range of India. Disjunctive kriging is applied firstly to compare estimates of the blocks by ordinary kriging and secondly to estimate benchwise local recoverable reserves of the orebody. Good agreement exists between block estimates by ordinary kriging and disjunctive kriging except for peripheral blocks with less borehole information. Estimation of benchwise reserves shows that the behavior of the distribution of grades is different in various benches. The study shows that disjunctive kriging can be applied successfully for estimation of local recoverable reserves in the case of a good grade hematite iron ore deposit.  相似文献   

由计算机产生的等距离区域分界线     

赖宝珍  费立凡 《武汉大学学报(信息科学版)》1988,(3)

本文介绍一种最近由作者在美国研制的,由计算机产生等距离区域分界线的程序及其数据结构,同时给出初步的试验结果。  相似文献   

磁尾宽频带静电噪声的一种新的激发机制          下载免费PDF全文

沐建林  濮祖荫  方正知 《地球物理学报》1988,31(6):613-621

本文提出了磁尾宽频带静电噪声强谱段的一种新的激发机制。在等离子体片边界层中存在着瞬时的局域性的晨昏电场。电子和离子对该电场的响应不同:在电场存在的区域内,电子作回旋漂移运动,而离子轨道在的时间尺度内可视为直线。由于等离子体片边界层中等离子体是非均匀的,这就导致了电荷分离的产生,从而可激发静电不稳定性。本文通过求解含电场的Vlasov方程,计算了由此产生的不稳定波的频率和增长率,考察了波矢方向。上述计算结果均与强谱段静电噪声的观测特征一致。  相似文献   

Seismic wave attenuation in fluid-saturated porous media     

James G. Berryman 《Pure and Applied Geophysics》1988,128(1-2):423-432

Contrary to the traditional view, seismic attenuation in Biot's theory of fluid-saturated porous media is due to viscous damping of local (not global) pore-fluid motion. Since substantial inhomogeneities in fluid permeability of porous geological materials are to be expected, the regions of highest local permeability contribute most to the wave energy dissipation while those of lowest permeability dominate the fluid flow rate if they are uniformly distributed. This dichotomy can explain some of the observed discrepancies between computed and measured attenuation of compressional and shear waves in porous earth. One unfortunate consequence of this result is the fact that measured seismic wave attenuation in fluid-filled geological materials cannot be used directly as a diagnostic of the global fluid-flow permeability.  相似文献   

Comparison of amplitude decay rates in reflection,refraction, and local earthquake records     

Bruce S. Gibson 《Pure and Applied Geophysics》1988,128(1-2):309-331

Three types of seismic data recorded near Coalinga, California were analyzed to study the behavior of scattered waves: 1) aftershocks of the May 2, 1983 earthquake, recorded on verticalcomponent seismometers deployed by the USGS; 2) regional refraction profiles using large explosive sources recorded on essentially the same arrays above; 3) three common-midpoint (CMP) reflection surveys recorded with vibrator sources over the same area. Records from each data set were bandpassed filtered into 5 Hz wide passbands (over the range of 1–25 Hz), corrected for geometric spreading, and fit with an exponential model of amplitude decay. Decay rates were expressed in terms of inverse codaQ (Q _c ^–1 ).Q _c ^–1 values for earthquake and refraction data are generally comparable and show a slight decrease with increasing frequency. Decay rates for different source types recorded on proximate receivers show similar results, with one notable exception. One set of aftershocks shows an increase ofQ _c ^–1 with frequency.Where the amplitude decay rates of surface and buried sources are similar, the coda decay results are consistent with other studies suggesting the importance of upper crustal scattering in the formation of coda. Differences in the variation ofQ _c ^–1 with frequency can be correlated with differences in geologic structure near the source region, as revealed by CMP-stacked reflection data. A more detailed assessment of effects such as the depth dependence of scattered contributions to the coda and the role of intrinsic attenuation requires precise control of source-receiver field geometry and the study of synthetic seismic data calculated for velocity models developed from CMP reflection data.  相似文献   

参数敏感性分析与试验方案优化   总被引：20，自引：2，他引：20  

章光  朱维申 《岩土力学》1993,14(1):51-58

在单因素敏感性分析的基础上,定义了无量纲形式的敏感度函数和敏感度因子,使得多因素敏感性分析具有可比性。作为算例,对拉西瓦地下工程的稳定性进行了敏感性分析。结果表明,水平向地应力σ_x和岩体弹性模量E是影响地下主厂房高边墙水平向变形的敏感因素。分析还表明,敏感因素与基准参数集有关,基准参数集不同,结论将有差异。本文还提出了试验方案优化的概念,并指出参数敏感性分析是试验方案优化的基础。  相似文献   

Influence of fluid chemistry on shear-wave attenuation and velocity in sedimentary rocks   总被引：2，自引：0，他引：2  

Dung Vo-Thanh 《Geophysical Journal International》1995,121(3):737-749

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