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《CT理论与应用研究》是中国地震局地球物理研究所和同方威视技术股份有限公司共同主办的专业性学术刊物,1992年创刊,主要刊登CT理论与应用方面的创新性研究成果,反映国内外CT科技的前沿和进展。期刊设有理论与方法、地球物理CT、工业CT、医学CT、综述和信息等栏目,     

地球物理数据网格化方法的选取

绘制地球物理数据等值线图时,需要根据客观环境特征和数据本身的特点,选择合适的网格化方法.通过实例,分别介绍了加权反距离插值法、克里格法、最小曲率法、最近邻点法、多项式回归法、径向基函数法、带线性插值的三角剖分法等常用网格化方法的选取方法、适用范围及参数设置等使用技巧.     

A synthetic aperture radar sea surface distribution estimation by n-order Bézier curve and its application in ship detection

To dates,most ship detection approaches for single-pol synthetic aperture radar(SAR) imagery try to ensure a constant false-alarm rate(CFAR).A high performance ship detector relies on two key components:an accurate estimation to a sea surface distribution and a fine designed CFAR algorithm.First,a novel nonparametric sea surface distribution estimation method is developed based on n-order Bézier curve.To estimate the sea surface distribution using n-order Bézier curve,an explicit analytical solution is derived based on a least square optimization,and the optimal selection also is presented to two essential parameters,the order n of Bézier curve and the number m of sample points.Next,to validate the ship detection performance of the estimated sea surface distribution,the estimated sea surface distribution by n-order Bézier curve is combined with a cell averaging CFAR(CA-CFAR).To eliminate the possible interfering ship targets in background window,an improved automatic censoring method is applied.Comprehensive experiments prove that in terms of sea surface estimation performance,the proposed method is as good as a traditional nonparametric Parzen window kernel method,and in most cases,outperforms two widely used parametric methods,K and G0 models.In terms of computation speed,a major advantage of the proposed estimation method is the time consuming only depended on the number m of sample points while independent of imagery size,which makes it can achieve a significant speed improvement to the Parzen window kernel method,and in some cases,it is even faster than two parametric methods.In terms of ship detection performance,the experiments show that the ship detector which constructed by the proposed sea surface distribution model and the given CA-CFAR algorithm has wide adaptability to different SAR sensors,resolutions and sea surface homogeneities and obtains a leading performance on the test dataset.     

Analyzing land-use change in farming-pastoral transitional region using autologistic model and household survey approach

Land change science （LCS） strives to understand and model land-use change, which will further advance the understanding of multiple issues in the socio-ecological systems. Based on GIS/RS techniques, autologistic model, and household survey method, this study investigated major land use changes and their causes from 1978 to 2008 in Uxin Banner （county-level）, Inner Mongolia in China and then developed an understanding of the relationships between household livelihood and land-use pattern. Results showed that cultivated land increased from 1988 to 2000, and leveled offafter 2000. Built-up land increased stably for the period 1978 2008. The change of grassland and bare land differed among the three periods. From 1978 to 1988, grassland increased by 23.3%, and bare land decreased by 20.48%. From 1988 to 2000, bare land expanded by 1.7%, but grassland declined by 1.3%. From 2000 to 2008, an increase in grassland area by 1.8% was observed, but a decrease in bare land area by 9.0% was witnessed. The autologistic models performed better than logistic models as indicated by lower Akaike Information Criterion （AIC） values. Factors associated with human activities significantly correlated with the change of cultivated land, forest land, grassland, and built-up land. The produce prices and extensive cultivated land use are major issues in the farming area. This study suggests that completing land circulation systems and maintaining the stability of price are effective solutions. By contrast, reclamation and overgrazing are major concerns in the pastoral areas. Implementing environmental policies effectively, transferring population out of rural pastoral areas, and developing modem animal husbandry are effective ways to address these issues.     

沉积型铝土矿预测方法及其影响因素——以贵州省铝土矿为例

以全国矿产资源潜力评价技术要求为基础,以贵州省铝土矿预测方法为实例,在简述国内沉积型铝土矿矿床类型、特征和预测方法的基础上,重点论述了地质单元法、网格单元法中划分预测单元、拟选预测要素和赋值的方法,以及地质填图精度、矿床特征、地-物-化-遥等信息对矿产预测的影响。该网格单元法考虑因素较全面,应用信息较充分,预测精度达到了矿体-矿床级。     

图像分析方法在土地定级中的应用与研究

结合传统土地级别划分方法的优点,本文研究了将定级工作中的多因素层网格与多波段图像对应起来,形成运用图像分析方法处理土地级别划分的理论模型,把“监督分类”与“非监督分类”的思想引入到定级区域的划分中来,充分发挥图像分析在多维分析方面算法成熟、手段多样的优点,从而能够更加科学准确地进行定级区域划分的工作。     

闪锌矿流体包裹体Ar-Ar定年研究进展

各种同位素年代学方法已广泛的应用于矿床成矿年龄的测定,然而,对大多数矿床来说,要准确其成矿年龄还存在一定的困难.对于金属硫化物矿床,由于难于找到既能够代表成矿时代、同时又适合于常规同位素定年方法的测定对象,难以对其进行直接定年.Re-Os和La-Ce法适用面很窄,只有少数的特殊矿物可作为测定对象,Rb-Sr、Sm-Nd和Pb-Pb等时线法常因一组样品同位素组成相近而不能构成等时线.热液矿床中矿物通常含有较丰富的流体包裹体,其中存在着一定量的钾.本文尝试用流体包裹体的40Ar-39Ar测年方法,对金属硫化物矿床进行直接定年分析.     

堆石料Gudehus-Bauer亚塑性本构模型改进及参数确定方法

研究了Gudehus-Bauer亚塑性本构模型和模型参数的求取方法。采用侧限压缩试验曲线求取模型参数颗粒硬度hs和指数n。根据模型方程的推导,建立了拟合指数 和 与围压之间的关系,并提出了新的拟合参数。考虑到堆石料具有明显的剪胀、剪缩性,在Gudehus-Bauer模型线性项中增加了主要控制体积应变项 ,以改善模型对堆石料体积应变曲线的描述。采用堆石料大型侧限压缩试验、常规三轴试验分别验证了新的拟合参数和改进后的Gudehus-Bauer亚塑性本构模型。与堆石料试验成果比较,提出的新拟合参数与改进后的Gudehus-Bauer亚塑性本构模型可以较好地模拟堆石料的应力-应变特性,并较好地改善了堆石料体变曲线的模拟结果。对改进后的模型作了常规三轴加、卸载模拟,模拟结果反映了改进的Gudehus-Bauer亚塑性本构模型具有一定的卸载适应性。     

犯罪热点时空分布研究方法综述

犯罪在地理时空内并不是均匀分布的,而是表现出明显的时空聚集特性,这种聚集性常用“犯罪热点”表述.基于对犯罪热点的理解,从犯罪热点时空分布模式、犯罪热点成因分析以及犯罪热点时空转移及预测等3 个方面总结了当前国内外犯罪热点时空分布相关研究方法的进展.最后,对该领域研究进行了总结与展望.总体上,国内相关研究较少,尚需进一步结合中国国情,提出适用方法.另外,也需要通过相关犯罪理论的深入研究以及其他领域研究方法的借鉴,实现犯罪热点时空分布研究方法的突破与创新.     

实数编码遗传算法在大地电磁测深二维反演中的应用

作为全局非线性优化的新方法之一的遗传算法,近年来已从生物工程流行到大地电磁测深资料解释中.然而,大地电磁反演问题具有不适定性,解的非唯一性.通过结合求解不适定问题的Tikhonov正则化方法,本文采用实数编码遗传算法求解大地电磁二维反演问题.此算法在构建目标函数时引入正则化的思想,利用遗传算法求解最优化问题.常规的基于局部线性化的最优化反演方法易使解陷入局部极小值,而且严重的依赖初始模型的选择.与传统线性化的迭代反演方法相比,实数编码遗传算法能够克服传统方法的不足且能获得更好的反演结果.通过对大地电磁测深理论模型进行计算,结果表明:该算法具有收敛速度快、解的精度高和避免出现早熟等优点,可用于大地电磁资料解释.