基于随机聚集维数的云南省峨山县城防灾空间布局评价研究     

刘樱  王培茗  施益军 《防灾减灾学报》2014,(3):5-10

城市防灾空间是城市的重要组成子系统,本文以地震高发的峨山县城（包括双江镇和小街镇）为研究对象,对县城防灾空间布局的分形特征进行研究,研究选取量化指标-随机聚集维数进行测算,意在对峨山县城城市防灾空间的分形特征进行验证,并对防灾空间布局体系进行分析。研究表明：1.峨山县双江镇和小街镇城市防灾空间布局具有分形结构;2.双江镇和小街镇城市防灾空间呈现二元分异结构;3.双江镇城市防灾空间受地震断裂带影响呈现多中心分形结构;4.小街镇防灾空间布局呈现一元化单中心分形结构。  相似文献   

正弦波交替音对黑鲷音响驯化的实验研究   总被引：1，自引：0，他引：1  

梁君  陈德慧  王伟定  章守宇  胡庆松 《海洋学研究》2014,32(2):59-66

音响驯化作为一种控制鱼群行为的技术,在海洋牧场开发中的应用前景广阔。在室内控温和投饵条件下,用300 Hz和400 Hz正弦波交替音对黑鲷(Sparus macrocephalus)进行音响驯化实验。结果表明,黑鲷对交替音的驯化效果经历了适应期、变化期和维稳期3个阶段;黑鲷的反应时间逐日缩短并逐渐接近对照组,第1~4天黑鲷的反应时间显著高于对照组(P<0.01),第5天开始对刺激产生正反馈,第10天低于对照组并出现实验期最小反应时间;聚集率则逐日增加并从第5天开始显著高于对照组 (P<0.01),第7天后聚集率稳定在100%;驯化后的黑鲷在饥饿状态下对音响刺激的兴奋度比饱食后相对更高。由此可见,300 Hz和400 Hz正弦波交替音对黑鲷的反应和聚集具有明显的效果,交替音可作为黑鲷音响驯化的一种有效手段,结合投饵可以在控制鱼类行为中发挥出更大作用。  相似文献   

中国农林牧渔业人口规模与产值规模的地理集散比较     

程前昌 《地域研究与开发》2010,29(5)

将信息熵指数分解为相对信息熵指数和绝对信息熵指数,以利于不同时空尺度横向差异与纵向差异的有效比较,并构造聚集度指数来直观反映中国农林牧渔业均匀分布状态所占的比例。20余年中,除个别年份外,全国、地带内和地带间农林牧渔业的绝对信息熵指数和相对信息熵指数起伏都不大,保持了较平稳的态势;全国、地带间及地带内的聚集度皆在70%以上,中国农林牧渔业呈现出小集中大分散的格局,而产值分布比从业人口分布更均衡。最后,通过劳动生产率区位商来描述从业人口与产值的对应关系。  相似文献   

A model of turbidity maximum maintenance in the Irish Sea   总被引：1，自引：0，他引：1  

K.M. Ellis  C.E. Binding  D.G. Bowers  S.E. Jones  J.H. Simpson 《Estuarine, Coastal and Shelf Science》2008,76(4):765-774

A two-dimensional model has been developed in order to improve understanding of the processes which interact to maintain the sediment concentrations at an isolated turbidity maximum in the Irish Sea throughout the year. The model comprises two interchangeable populations of particles with different diameters, one of fine cohesive material, the other made up of flocs. Both populations are slow settling, and subject to horizontal diffusion, resuspension, settling, aggregation and disaggregation.The equations used to describe the processes of aggregation and the break-up of flocs in response to sediment concentration and turbulent shear have been developed by the tuning of the model to observations. Due to high turbulent shear at the turbidity maximum, the particles are predominantly fine, while the sediment in the surrounding water is made up of larger flocs. Diffusion of small particles out of the turbidity maximum balanced by the diffusion of aggregated material towards it provides a mechanism for its maintenance. The modelled sediment concentrations at the turbidity maximum can be reproduced year-on-year, with no loss due to diffusive processes. This is achievable with a limited, exhaustible source of material which is not replenished once resuspended.Through comparison with satellite imagery the correlation of the modelled sediment concentrations with observations is investigated, both spatially and temporally. The seasonal cycle is reproduced well by the model with winter and summer concentrations matching those observed. Spatially the model also performs well in both turbid regions and those where the surface sediment load is low.  相似文献   

冀东长城式金矿构造地质特征及构造演化与金矿化的关系   总被引：2，自引：0，他引：2  

樊秉鸿  杨文思  王郁  汪振彬 《地质找矿论丛》1998,13(4):38-45

长城式金矿是产在中晚元古宇碳酸岩中的一种新类型金矿,本文从金矿床的构造地质特征及其演化的角度,阐述了长城式金矿构造与金矿化的独特关系。  相似文献   

Comparing commercial and research survey catch per unit of effort: megrim in the Celtic Sea     

Petitgas  Pierre; Poulard  Jean Charles; Biseau  Alain 《ICES Journal of Marine Science》2003,60(1):66-76

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Estimation and compensation models for the shadowing effect in dense fish aggregations   总被引：1，自引：1，他引：1  

Zhao  Xianyong; Ona  Egil 《ICES Journal of Marine Science》2003,60(1):155-163

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Diel variations in acoustic recordings of blue whiting (Micromesistius poutassou)     

Johnsen  E.; Godo  O. R. 《ICES Journal of Marine Science》2007,64(6):1202-1209

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BinSq: visualizing geographic dot density patterns with gridded maps     

Alvin Chua  Andrew Vande Moere 《制图学和地理信息科学》2017,44(5):390-409

ABSTRACT

Dot maps have become a popular way to visualize discrete geographic data. Yet, beyond showing how the data are spatially distributed, dot maps are often visually cluttered in terms of consistency, overlap, and representativeness. Existing clutter reduction techniques like jittering, refinement, distortion, and aggregation also address this issue, but do so by arbitrarily displacing dots from their exact location, removing dots from the map, changing the spatial reference of the map, or reducing its level of detail, respectively. We present BinSq, a novel visualization technique to compare variations in dot density patterns without visual clutter. Based on a careful synthesis of existing clutter reduction techniques, BinSq reduces the wide variety of dot density variations on the map to a representative subset of density intervals that are more distinguishable. The subset is derived from a nested binning operation that introduces order and regularity to the map. Thereafter, a dot prioritization operation improves the representativeness of the map by equalizing visible data values to correspond with the actual data. In this paper, we describe the algorithmic implementation of BinSq, explore its parametric design space, and discuss its capabilities in comparison to six existing clutter reduction techniques for dot maps.  相似文献   

四川省城镇体系空间结构的分形研究     

尤小刚  夏春林 《测绘与空间地理信息》2017,(12):81-83,86

针对四川省的城镇化进程与城市空间格局,采用了分形理论法,对四川省城镇体系的等级规模结构和空间结构进行了研究。得出了四川省城镇体系总体特征,可对四川省今后的区域规划提供借鉴参考作用。  相似文献