电子地形图符号体系的研究

随着数字制图技术的发展,电子地图的应用日益增多,为保证地理信息感知和认知的一致性与准确性,达到信息与资源共享,电子地形图符号的规范化、标准化势在必行。文中针对此种需求介绍了电子地形图符号体系和符号标准化的研究现状,分析了电子地形图符号体系中存在的主要问题,详细阐述了电子地形图符号体系构建的基本原则、内容以及体系结构,并且结合示例进行了说明,为电子地形图符号体系的研究提供了一些思路。     

Statistical empirical index of chemical weathering in igneous rocks: A new tool for evaluating the degree of weathering

Chemical weathering indices are useful tools in characterizing weathering profiles and determining the extent of weathering. However, the predictive performance of the conventional indices is critically dependent on the composition of the unweathered parent rock. To overcome this limitation, the present paper introduces an alternative statistical empirical index of chemical weathering that is extracted by the principal component analysis (PCA) of a large dataset derived from unweathered igneous rocks and their weathering profiles. The PCA analysis yields two principal components (PC1 and PC2), which capture 39.23% and 35.17% of total variability, respectively. The extent of weathering is reflected by variation along PC1, primarily due to the loss of Na₂O and CaO during weathering. In contrast, PC2 is the direction along which the projections of unweathered felsic, intermediate and mafic igneous rocks appear to be best discriminated; therefore, PC1 and PC2 represent independent latent variables that correspond to the extent of weathering and the chemistry of the unweathered parent rock. Subsequently, PC1 and PC2 were then mapped onto a ternary diagram (MFW diagram). The M and F vertices characterize mafic and felsic rock source, respectively, while the W vertex identifies the degree of weathering of these sources, independent of the chemistry of the unweathered parent rock.

The W index has a number of significant properties that are not found in conventional weathering indices. First, the W index is sensitive to chemical changes that occur during weathering because it is based on eight major oxides, whereas most conventional indices are defined by between two and four oxides. Second, the W index provides robust results even for highly weathered sesquioxide-rich samples. Third, the W index is applicable to a wide range of felsic, intermediate and mafic igneous rock types. Finally, the MFW diagram is expected to facilitate provenance analysis of sedimentary rocks by identifying their weathering trends and thereby enabling a backward estimate of the composition of the unweathered source rock.     

Analysis on the noises from continuously monitoring GPS sites

In this paper,we analyze the time series of site coordinates of 27 continuously monitoring GPS sites covered bythe Crustal Movement Observation Network of China over the whole country.The data are obtained in the periodfrom the beginning of the observation to the November of 2005.On the basis of data processing,we analyze thepower spectrum density of coordinate component noise at each site and calculate the spectral indexes manifestingthe noise property of each component.The spectral indexes indicate that for most sites,the noise of time series ofeach coordinate component can be addressed by the model of white noise flicker noise;and for a small amountof sites,it can be described by the model of white noise flicker noise random walk noise.We also quantita-tively estimate each noise component in the model by using the criterion of maximum likelihood estimation.Theresult shows that the white noise in the time series of GPS site coordinates does not constitute the main part ofnoise.Therefore,the error estimation of site movement parameters is usually too small,or too optimistic if weconsider the white noise only.Correspondingly,if this factor is not fully considered in explaining these movementparameters,it might mislead the readers.     

Implications of broad dose distributions obtained with the single-aliquot regenerative-dose method on quartz fine-grains from loess

Six samples were collected from a section of Peoria Loess in Eustis, North America, for optically stimulated luminescence (OSL) dating of quartz, and all except one (LV90) produced narrow dose distributions. A comparative study was conducted on this sample and on a ‘well-behaved’ sample (LV91), involving other dating methods and examination of the quartz OSL. These investigations revealed differences in the quartz OSL growth with dose, OSL response to thermal treatments and the range of components within the OSL signals. An ultra-fast component was found in LV90 that displayed a higher rate of sensitivity change than the fast component and this had a malign influence on the determination of the equivalent dose. The distinctive luminescence characteristics of LV90 imply either a change in wind dynamics and/or the source area for the silt.     

提高地磁绝对观测数据精度的有效途径

经过长期观察发现用CZM-2型核旋仪(及其同类仪器)进行定点观测读数时,运用分量仪线圈“单向”旋转的方法进行分量观测,再加上做好一些其它辅助措施,能够充分消除人为因素和仪器本身误差所带来的影响,明显提高仪器的观测精度,达到使观测资料更加准确的目的。     

北方落叶果树嫁接适宜气象条件调查与研究

本文介绍了山西省气象局气象科技数字图书馆的构架及服务功能，从数字图书馆技术方面分析了气象科技图书馆的主要特点，同时对数字图书馆开通以来的使用情况进行了统计分析，为数字图书馆的进一步完善和发展提出构想。     

1480型多普勒天气雷达中尺度气旋识别模块设计

借鉴国内外中尺度气旋识别算法的研究成果特别是NSSL(National Severe Storm Laboratory)的中尺度气旋识别算法,结合多普勒天气雷达二次产品软件的特点,提出了改进的中尺度气旋识别算法,以动态链接库的形式,设计完成了中尺度气旋识别模块.对2002年5月27日安徽省北部地区的一次强对流天气过程的雷达资料进行了分析,并与北京敏视达(METSTAR)雷达有限公司Build 10.8软件系统生成的中尺度气旋产品进行了对比分析,结果表明该模块有比较好的识别能力,预警效果较好.     

一种简化的Helmert方差分量估计算法

Ｈｅｌｍｅｒｔ方法是通过求出两类观测值的单位方差,来修正其先验权,用迭代法最终求得正确的权。本文提出,如果已知两类观测值的单位方差之比,即可定出正确的权,从而使计算简单化。     

全球地震震中数据库及数据格式

全球震中光盘数据库３．０版,向科研单位及所有用户提供地震震中资料。包括地震震中的地理位置,震级大小及震源深度,和发震时间都存贮在光盘地震数据库。通过人机对话方式进行地震数据的存取。     

TRES-Ⅰ型多分量瑞利波勘探仪的研究及应用

提出多分量瑞利波勘探的技术思想和方法,研制成功专用的防爆型多分量瑞利波勘探仪器,建立了在用极化分析对瑞利波勘探记录的多分量信号分析的基础上,用极化滤波提取有效瑞利波信号的方法。在煤矿井下及地面实际应用表明,多分量瑞利波勘探与单分量法比较,信号的信噪比、勘探深度和可靠性均有一定的提高。