面向土地利用调查的时空数据库构建技术   总被引：1，自引：0，他引：1  

郜允兵  潘瑜春  高秉博  张晓东  郜俊霞  张翼鹏 《测绘科学》2015,40(5)

为了满足"一调""二调"等不同时期土地利用变化数据管理与分析的需要,文章在分析时态数据库构建中存在的问题的基础上,引入变更事件、重建事件和多基态,建立了基于事件组的多基态修正模型,实现了"一调""二调"土地利用数据一体化存储;针对"一调""二调"空间数据不一致的几何重建和语义转换问题,提出通过重建事件表实现重建前后要素归档及查询;同时,针对土地利用数据管理的现状以及数据形态,提出了土地利用变更增量提取、时态拓扑关系构建的方法,实现了土地利用时空数据库的构建。最后,以武汉市汉南区数据为例开发了原型系统,实验结果表明本文提出的模型、方法具有较强的实用性。  相似文献   

目标相似性的矢量数据联动更新方法     

汪艳霞  杜清运  任福  赵志远 《测绘科学》2015,40(5):106-111

针对地理空间矢量数据更新和相似性在地理信息领域应用的研究现状,文章分析了不同几何类型目标之间的几何相似性,结合属性相似度,提出了针对数据联动更新的目标相似性的计算模型以及目标匹配方法;在此基础上,提出了数据变化发现和提取方法,并依据数据之间的映射关系实现多重表达矢量数据的联动更新。最后以某省矢量数据的水系要素之间联动更新为实例,证明了本数据联动更新方法能够完成多重表达地理空间矢量数据的更新,同时保证数据之间的一致性。  相似文献   

利用地标空间关系约束的点实体匹配方法     

温伯威  阚映红  马京振 《测绘科学技术学报》2015,(3):326-330

针对传统的点实体匹配方法的不足,提出了利用地标空间关系约束的点实体匹配方法。该方法以参考点实体、候选匹配点实体与其邻域内的同名地标之间的空间关系为基础构造距离特征向量和方向特征向量,基于距离特征向量和方向特征向量计算点实体的相似度,进而确定点同名实体。实验结果表明,该方法在点同名实体空间位置偏差较大的情况下依然能够取得很好的效果,验证了该方法的有效性。  相似文献   

大孔径闪烁仪观测中的相似理论适用性分析     

郭伟  刘寿东  刘绍民  徐自为 《高原气象》2013,32(4)

利用2009年馆陶站(1-12月)和阿柔站(1-6月和10-11月)的大孔径闪烁仪LAS相关数据,分析了LAS观测中莫宁—奥布霍夫相似理论MOST理论的适用性,并探讨了MOST理论适用性的定量判断方法.结果表明:(1)在不稳定条件下,大尺度涡旋运动、大气湍流发展状况和温度尺度都能对MOST理论适用性产生显著影响;(2)确立了两种新的MOST理论适用性判断方法,即因子分析法和温度结构参数法,并验证了这两种判断方法是合理、可靠的.  相似文献   

Trophic modeling of the Northern Humboldt Current Ecosystem, Part II: Elucidating ecosystem dynamics from 1995 to 2004 with a focus on the impact of ENSO   总被引：1，自引：1，他引：0  

Marc H. Taylor  Jorge Tam  Vernica Blaskovic  Pepe Espinoza  R. Michael Balln  Claudia Wosnitza-Mendo  Juan Argüelles  Erich Díaz  Sara Purca  Noemi Ochoa  Patricia Ayn  Elisa Goya  Dimitri Gutirrez  Luis Quipuzcoa  Matthias Wolff 《Progress in Oceanography》2008,79(2-4):366

The Northern Humboldt Current Ecosystem is one of the most productive in the world in terms of fish production. Its location near to the equator permits strong upwelling under relatively low winds, thus creating optimal conditions for the development of plankton communities. These communities ultimately support abundant populations of grazing fish such as the Peruvian anchoveta, Engraulis ringens. The ecosystem is also subject to strong inter-annual environmental variability associated with the El Niño Southern Oscillation (ENSO), which has major effects on nutrient structure, primary production, and higher trophic levels. Here our objective is to model the contributions of several external drivers (i.e. reconstructed phytoplankton changes, fish immigration, and fishing rate) and internal control mechanisms (i.e. predator-prey) to ecosystem dynamics over an ENSO cycle. Steady-state models and time-series data from the Instituto del Mar del Perú (IMARPE) from 1995 to 2004 provide the base data for simulations conducted with the program Ecopath with Ecosim. In simulations all three external drivers contribute to ecosystem dynamics. Changes in phytoplankton quantity and composition (i.e. contribution of diatoms and dino- and silicoflagellates), as affected by upwelling intensity, were important in dynamics of the El Niño of 1997–98 and the subsequent 3 years. The expansion and immigration of mesopelagic fish populations during El Niño was important for dynamics in following years. Fishing rate changes were the most important of the three external drivers tested, helping to explain observed dynamics throughout the modeled period, and particularly during the post-El Niño period. Internal control settings show a mix of predator–prey control settings; however a “wasp-waist” control of the ecosystem by small pelagic fish is not supported.  相似文献   

THE FREE-WILSON PARADIGM REDUX:SIGNIFICANCE OF THE FREE-WILSON COEFFICIENTS,INSIGNIFICANCE OF COEFFICIENT ‘UNCERTAINTIES’ AND STATISTICAL SINS     

DAVID LEE DUEWER 《地理学报(英文版)》1990,(4)

The Free-Wilson paradigm is an established and powerful tool for quantitatively relating activity withchemical structure.Current implementations of the paradigm,however,are flawed both conceptually andin execution.As part of an attempt to more fully realize the promise of the paradigm,it was necessaryto examine these limitations in detail.This report introduces a robust,theory-founded Free-Wilson implementation:stepwise principalcomponents regression analysis(SPCRA).SPCRA is computationally superior to previousimplementations but does not in itself correct their conceptual flaws.The development of SPCRA did,however,facilitate derivation of a simple and chemically significantinterpretation of the Free-Wilson structure-activity model.A number of statistical aspects of this modelcommonly misused in previous applications are discussed at length.These discussions provide criticalbackground for the development of an alternative implementation of the Free-Wilson paradigm.  相似文献   

Assessing cause and effect of multiple stressors on marine systems     

Adams SM 《Marine pollution bulletin》2005,51(8-12):649-657

An operational framework is developed to serve as a guideline for investigating causal relationships between environmental stressors and effects on marine biota. Because of the complexity and variability of many marine systems, multiple lines of evidence are needed to understand relationships between stressors and effects on marine resources. Within this framework, a weight of evidence approach based on multiple lines of evidence are developed and applied in a sequential manner by (1) characterizing the study system which involves determining if target biota are impaired, assessment of food and habitat availability, and measuring contaminant levels in the environment, (2) assessing direct effects of contaminant exposure on target biota using biomarkers and assessing indirect effects of exposure using suites of bioindicators, and (3) applying standard causal criteria based on epidemiological principles and diagnostic health profiling techniques to assess potential causes. Use of multiple lines of evidence should also reduce the risk of false positives (Type I error or falsely concluding that there is a causal relationship when there is none) and false negatives (Type II error or falsely concluding there is not a causal relationship when there actually is). Understanding causal relationships and the mechanistic processes between environmental stressors and effects on biota is important in the effective management and restoration of impaired marine ecosystems.  相似文献   

Treatment of ground-motion predictive relationships for the reference seismic hazard map of Italy     

Valentina?MontaldoEmail author  Ezio?Faccioli  Gaetano?Zonno  Aybige?Akinci  Luca?Malagnini 《Journal of Seismology》2005,9(3):295-316

In the framework of the 2004 reference seismic hazard map of Italy the amplitude of the strong-motion (expressed in terms of Peak Horizontal Acceleration with 10% probability of non-exceedence in 50 years, referred to average hard ground conditions) was computed using different predictive relationships. Equations derived in Italy and in Europe from strong-motion data, as well as a set of weak and strong-motion based empirical predictive relationships were employed in a logic tree procedure, in order to capture the epistemic uncertainty affecting ground-motion attenuation. This article describes the adjustments and conversions required to eliminate the incompatibilities amongst the relations. Particularly significant are distance conversions and style-of-faulting adjustments, as well as the problems related to the use of regional relations, such as the selection of a reference depth, the quantification of random variability and the strong-motion prediction. Moreover, a regional attenuation relationship specific for volcanic areas was also employed, allowing a more realistic evaluation of seismic hazard, as confirmed by the attenuation of macroseismic intensities.  相似文献   

The Neutral, Barotropic Planetary Boundary Layer, Capped by a Low-Level Inversion     

G. D. Hess 《Boundary-Layer Meteorology》2004,110(3):319-355

The presence of a low-level, capping inversion layer will affect the height and structure of the planetary boundary layer (PBL). Results from models of varying levels of sophistication, including analytical, turbulent kinetic energy (TKE), second-order closure (SOC), large-eddy simulation (LES) and direct numerical simulation (DNS) models, are used to investigate this influence for the neutral, barotropic PBL. Predicted and observed profiles of stress and geostrophic departure components, and integral measures, such as the parameters of Rossby-number similarity theory, are compared for the KONTUR, Marine Stratocumulus, JASIN, Leipzig, Pre-Wangara and Upavon field experiments.Analytical models of the equilibrium value of inversion height z_i, which depend on the surface friction velocity u_*, and both the Coriolis parameter f and the free-flow Brunt-Väisälä frequency N, are found to give reasonable estimates of the PBL height. They also indicate that only the KONTUR and Marine Stratocumulus experiments were strongly influenced by N. More quantitative comparisons would require larger, more comprehensive datasets. The effects of the presence of a capping inversion on the profile structure were found to be insignificant for h_* = |f|z_i/u_* > 0.15.The simple analytical model performed quite well over all values of h_*; it predicted the profiles of the longitudinal stress component (in the direction of the surface stress) better than the lateral component. The more advanced models performed well for small values of h_* (for flow over the sea), but systematically underestimated the cross-isobaric angle for flow over land. These models predicted the profiles of the lateral stress component better than the longitudinal component. The profiles of the analytical model agreed with those of the advanced models when the constant eddy viscosity of the outer layer was increased.Agreement with DNS was achieved by increasing the eddyviscosity of the analytical model by a factor of 5.Zilitinkevich and Esau(2002, Boundary-Layer Meteorology, 104, 371–379)suggest that the neutral, barotropic values of A and B of Rossby-numbersimilarity theory are not universal constants, but depend on the ratio N/|f|. The dependence for A and B is calculated using the analytical model and TKE models. Over the sea (h_* 0.1; N/|f| 100, where we have used the Zilitinkevich-Esau relation to convert between h_* and N/|f|) there is agreement between the model predictions and observations; however over land where the equilibrium boundary-layer height is greater (h_* 0.35; N/|f| 10) the inconsistency between the advanced model predictions (TKE, SOC, LES, and DNS) and observations, as noted previously by Hess and Garratt, still exists. We attribute this disagreement to violations of the strict assumptions of steady, horizontally homogeneous, neutral, barotropic conditions implicit in the observations. At small values of z_i and a strongly stable background stratification (h_* 0.04; N/|f| 1000) both the TKE and analytical models predict that A and B depend significantly on h_*, however observations are unavailable to confirm these predictions. Zilitinkevich and Esau call this case the `long-lived near-neutral PBL', and state that it is found in cold weather at high latitudes.  相似文献   

Seismic ground motion relationship in southern China based on stochastic finite-fault model   总被引：1，自引：0，他引：1  

郑斯华  黄玉龙 《地震工程与工程振动(英文版)》2004,3(1):11-21

The characteristics of seismic ground motions in southern China are difficult to determine statistically due to a lack of strong ground motion data. In this study, a stochastic finite-fault ground motion model was adopted to simulate the seismic ground motions at bedrock for southern China, based on parameters derived from small and medium earthquakes that have occurred in the region. From these, the response spectra was estimated. A set of ground motion attenuation relations hipswas then developed based on simulated peak ground motions and response spectral parameters through regression, which would be applicable for use in engineering practice. Through comparisons, it was demonstrated that the proposed ground motion relationships are generally consistent with those obtained from other reported ground motion attenuation models for southern China.  相似文献