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31.
An Open Source C++ inversion framework for magnetic interpretation, including UXO applications, has been developed. The point dipole model is used to approximate a small magnetic object. However, alternative object models can be easily accommodated. Input data can be presented in a variety of formats and physical units including, but not limited to, profiles of the total magnetic field, uniform data grids, random data points, magnetic gradients, and finite magnetic difference measurements. Well-established external numerical optimization software modules such as the SLATEC (Common Mathematical Library, Los Alamos National Laboratory) package are used to solve numerical problems. Other software modules can easily be incorporated as they become available. Some practical examples of the application of the framework using total field data and vertical total field gradient data from a UXO test range are presented. We have decided to “open-source” the toolkit. It can be downloaded without charge under GNU Public License via anonymous FTP from ftp://geom.geometrics.com/pub/mag/Software/magtoolkit-1.0.zip. 相似文献
32.
Abdessamad Najine Mohammed Jaffal Kamal El Khammari Tahar Aïfa Driss Khattach Mahjoub Himi Albert Casas Said Badrane Hicham Aqil 《Comptes Rendus Geoscience》2006,338(10):676-682
This study is based on the analysis and the interpretation of the gravity data of the Tadla basin. Its purpose is to increase the knowledge of this basin structure. A residual anomaly map was first calculated from the Bouguer anomaly data witch are strongly affected by a regional gradient. The computed map provides information on the ground density variation but it does not bring enough of new elements. Data filtering allows us to emphasize the structures affecting the basin. We chose the horizontal gradient coupled to the upward continuation techniques that permit to highlight news structures and to give information on their dip. The elaborated structural map of the study area constitutes a useful document for rationalizing the future groundwater exploration in the Tadla basin. To cite this article: A. Najine et al., C. R. Geoscience 338 (2006). 相似文献
33.
冰川槽谷横剖面沿程变化及其对冰川动力的反映 总被引:3,自引:0,他引:3
冰川槽谷梯级宽深比定义为槽谷槽剖面上相同等高线间距离与对应深度的比值。它可以描述槽谷横剖面形态的总体特征,便于不同槽谷横剖面形态的对比。统计分析表明槽谷梯级宽深比随槽谷深度的变化幂函数模型。使用这一模型描述冰川槽谷横剖面的总体形态并据此探讨冰川槽谷横剖面形态的沿程变化。主要结论如下:简单槽谷从上源到雪线附近,模型参数显示为槽谷展宽,谷壁变陡,从雪线向下游,槽谷变窄,谷壁变缓;从简单槽谷段向槽谷段, 相似文献
34.
Yan Ming Wang 《Marine Geodesy》2000,23(4):251-258
Historically, prediction of ocean floor depth, or bathymetry, has been based on the isostatic modeling and linearized relationships between gravity anomalies and bathymetry. The need for isostatic modeling limits the application of the resulting bathymetry predictions as constraints in geophysical models. An alternative technique making use of the Earth's vertical gravity gradient for predicting bathymetry is explored in this paper. This technique is based on the fact that the observed gravity gradient anomalies result primarily from local mass concentrations on the ocean floor, and that mass compensation by the oceanic crust has an insignificant effect on the gravity gradients, and can be neglected. The resulting bathymetry prediction therefore is independent of isostatic modeling assumptions, allowing it to be used as a constraint on models of lithospheric compensation and for other geodetic and geophysical applications. 相似文献
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A savanna system is a natural ecosystem in which the competition between grass and woody vegetation in a semi-arid rangeland should be maintained for its sustainable development. Finding an optimal management plan for obtaining maximum economic profit from raising cattle without loss of sustainability of the savanna system during a planning period is a great challenge for rangeland managers. In this study, we formulate the sustainable development planning of the savanna system as an optimal control model, in which maximization of the stocking rate of cattle during the planning period is chosen as the objective while sustainable development requirements are achieved through the constraints represented by the desired final state of the system. Using Pontryagin's maximum principle, the model is transformed into a two-point boundary-value problem with nonlinear differential equations that is then solved using an iterative approach. An example with a specified desired final state in a savanna system without fire is used to demonstrate the performance of the model and the algorithm. Numerical experiments show that the planning strategy obtained from the optimal control model achieves maximum economic profit from raising cattle during the planning period and simultaneously improves the resilience of the system and maintains sustainable development of the rangeland. The outcomes demonstrate that resilience, sustainable development and economic profit are consistent concepts in optimal management strategy for rangeland management. 相似文献
39.
以珠三角空间梯度上的核心区广州、近郊区肇庆鼎湖及远郊区怀集三地的葫芦藓为研究对象,对其重金属污染进行研究。结果显示:珠三角地区葫芦藓重金属含量呈明显的梯级分布,其中Cu、Pb、Zn、Cr、Cd含量均表现为广州最高,分别为47.64、68.83、252.87、64.20和1.02mg/kg;肇庆次之,分别为36.34、40.51、143.49、51.29和0.64mg/kg;怀集最低,分别为16.42、11.80、97.13、32.43和0.21mg/kg。珠三角地区葫芦藓内不同重金属的含量差异反映了来源差异,其中Cd、Pb、Zn和Cu之间呈显著正相关关系,反映了重金属元素来自于相同的污染源;而Cr与Cd、Pb、Cu和Zn的相关性相对弱一些,说明Cr的污染源与其他元素存在一些差异,或者说这个元素与其他元素同时污染大气的可能性相对小一些。分析进一步揭示,三地葫芦藓污染同三地大气污染以及工业化进程存在一定的耦合性。基于此,指出葫芦藓可作为研究环境污染的指示标志,具有重要的环境指示意义。 相似文献
40.
GOCE卫星重力测量中有色噪声滤波器设计 总被引:1,自引:0,他引:1
本文根据卫星重力梯度测量的有色噪声特性,设计了Wiener、AR、FIR三种滤波器,并利用模拟的有色噪声数据对其滤波效果进行了测试,结果表明:对于文中采用的有色噪声数据,AR的滤波效果最好,其次为Wiener滤波器,FIR的滤波效果最差;三种滤波器均可用于GOCE卫星重力测量中有色噪声数据滤波,但其实用性尚需利用实测数据进行检验;可以利用不同的滤波器对含有色噪声的卫星重力梯度数据进行多次滤波,以进一步减弱有色噪声对卫星重力梯度测量精度的影响. 相似文献