Canonical planetary perturbation equations for velocity-dependent forces,and the Lense-Thirring precession

A form of planetary perturbation theory based on canonical equations of motion, rather than on the use of osculating orbital elements, is developed and applied to several problems of interest. It is proved that, with appropriately selected initial conditions on the orbital elements, the two forms of perturbation theory give rise to identical predictions for the observable coordinates and velocities, while the orbital elements themselves may be strikingly different. Differences between the canonical form of perturbation theory and the classical Lagrange planetary perturbation equations are discussed. The canonical form of perturbation theory in some cases has advantages when the perturbing forces are velocity-dependent, but the two forms of perturbation theory are equivalent if the perturbing forces are dependent only on position and not on velocity. The canonical form of the planetary perturbation equations are derived and applied to the Lense Thirring precession of a test body in a Keplerian orbit around a rotating mass source.     

Stochastic modeling of gold mineralization in the Champion lode system of Kolar gold fields (India)

Stochastic modeling of gold mineralization in the Champion lode of Kolar gold fields was carried out using assay data taken from developmental headings. After dividing the lode into 71 horizontal and 18 vertical strata, autoregressive (AR), moving average (MA), and autoregressive and moving average (ARMA) models were developed and applied. The model selection with the acf and pacf for the various strata showed that in most of the cases, ARMA modeling of first-order would forecast gold headings with a reasonable degree of confidence. This was substantiated by comparing the coefficients of variation. From a parsimony point of view, AR (1) model may also be considered valid. The best overall models are: ARMA (1, 1), ; AR (1), , where a_t is N (0, _a ² ), x is in logarithms of in-dwt, and t is in block units of 100 ft. The applications of these models to a specific stratum are given. These models would also be helpful to describe the characteristics of the gold mineralization process of this lode.     

Responses of aboveground biomass of alpine grasslands to climate changes on the Qinghai-Tibet Plateau

Aboveground biomass in grasslands of the Qinghai-Tibet Plateau has displayed an overall increasing trend during 2003-2016, which is profoundly influenced by climate change. However, the responses of different biomes show large discrepancies, in both size and magnitude. By applying partial least squares regression, we calculated the correlation between peak aboveground biomass and mean monthly temperature and monthly total precipitation in the preceding 12 months for three different grassland types (alpine steppe, alpine meadow, and temperate steppe) on the central and eastern Qinghai-Tibet Plateau. The results showed that mean temperature in most preceding months was positively correlated with peak aboveground biomass of alpine meadow and alpine steppe, while mean temperature in the preceding October and February to June was significantly negatively correlated with peak aboveground biomass of temperate steppe. Precipitation in all months had a promoting effect on biomass of alpine meadow, but its correlations with biomass of alpine steppe and temperate steppe were inconsistent. It is worth noting that, in a warmer, wetter climate, peak aboveground biomass of alpine meadow would increase more than that of alpine steppe, while that of temperate steppe would decrease significantly, providing support for the hypothesis of conservative growth strategies by vegetation in stressed ecosystems.     

Petrogenesis of Ultramafic Rocks from the Ultrahigh-pressure Metamorphic Kimi Complex in Eastern Rhodope (NE Greece)

Widespread bodies of garnet–spinel metaperidotites withpyroxenitic layers occur in the ultrahigh-pressure metamorphicKimi Complex. In this study we address the origin of such peridotite–pyroxeniteassociations in the context of polybaric melting regimes. Weconduct a detailed geochemical investigation of major and traceelement relations and compare them with a range of major elementmodelling scenarios. With increasing bulk-rock MgO content,the garnet–spinel metaperidotites exhibit decreasing CaO,Al₂O₃, TiO₂, and Na₂O along with increasing Ni and a graduallyincreasing Zr/Zr* anomaly, consistent with an origin as residuesafter variable degrees of melt extraction. The major elementmodelling further suggests a polybaric adiabatic decompressionmelting regime beginning at high to ultrahigh pressure, withan intermediate character between pure batch and fractionalmelting and a mean extent of melting of 9–11%. The pyroxenitesexhibit major element compositions that cannot be reproducedby experimental or calculated melts of peridotite. Moreover,the Kimi pyroxenites have highly variable Ni and Sc contentsand a wide range of Mg-number (0· 76–0·89), inconsistent with an origin as frozen melts or the productsof melt–peridotite interaction. However, both the majorelement systematics and the observed rare earth element patterns,with both convex and concave shapes, can be explained by anorigin as clinopyroxene-rich, high-pressure cumulates involvinggarnet and/or Cr-spinel. KEY WORDS: peridotite; pyroxenite; partial melting; UHP metamorphism; cumulate     

顾及尺度变化和数据更新的道路网匹配算法

道路网数据匹配是地理空间数据库进行变化探测和数据更新的重要前提,不同比例尺下的道路网之间的匹配是一个非常重要的部分。本文总结和分析了道路网匹配的已有算法,针对不同比例尺道路网之间的匹配可能存在的问题和难点,设计了一个融合多种匹配技术的算法。在考虑不同比例尺下道路网数据的特点基础上,改进了空间场景结构的评价方法;分析了stroke匹配算法在不同比例尺道路网数据下的局限性,提出了一种可针对不同比例尺下道路数据存在变化与更新的stroke部分匹配算法。试验表明,文中所提出的方法能够适应不同比例尺下道路网的匹配,匹配效果较好,运行效率较高。     

北京西山晚侏罗世粗安岩的成因及其地质意义

北京西山晚侏罗世髫髻山组粗安岩具有高的SiO     

Observed advantage for negative binomial over Poisson distribution in partial duration series

The goodness of fit of the negative binomial and the Poisson distributions to partial duration series of runoff events is tested. The data have been recorded by eight hydrometric stations located on ephemeral rivers in Isreal. For each station, a number of threshold discharges are considered, by that series of nested subsamples are formed. Owing to size limitations, a Chi-square test is conducted on samples associated with low to moderate threshold discharges. Positive results, at a 5% significance level, are obtained in 30 out of the 53 tests of the Poisson distribution, and in 22 out of the 28 tests of the negative binomial distribution. The fit of the Poisson distribution to samples of conventionally recommended sizes (of 2 to 3 events per year) is found positive for five rivers and negative for the three other rivers The fit of the negative binomial distribution to these samples is found positive for six rivers, inconclusive for one river and short of data for the eighth river. Mixed results are obtained as the threshold level is raised. Therefore, no direct extrapolation is possible to samples associated with high thresholds.An indirect extrapolation is drawn through a comparison of the actual properties of the samples with those expected under a perfect fit of the distribution functions. Ranges of such properties are defined with respect to the properties of the tested samples and to the test results. The actual properties of nine of the eleven samples associated with high thresholds (i.e. mean number of events <-0.1year ^–1) are found within these ranges. This provides a hint for a probable good fit of either distribution, and particularly the negative binomial, to the occurrence frequency of high events.     

Evaluating the Effects of Autofluorescence during Raman Hyperspectral Imaging

Raman hyperspectral imaging is becoming a popular technique to analyse geological materials. Autofluorescence can affect the quality of the spectra that comprise hyperspectral data sets. Few studies have addressed potential misinterpretation of Raman images from hyperspectral data sets affected by autofluorescence. Additionally, little work has been done to develop methods for identifying the spatial distribution of spectra affected by autofluorescence. This study illustrates how autofluorescence may lead to misinterpretation of the distribution of materials based on intensity at a point images. A method is proposed utilising signal to axis analysis to create images that identify regions affected by autofluorescence. Post‐processing baseline correction is often used to address autofluorescence, and most software programs utilise a form of partial least squares regression modelling based on a subjective choice of polynomial order. This study shows that an inappropriate choice of polynomial order can introduce error, which may lead to misinterpretation of Raman images. A signal to axis analysis method is proposed to statistically compare seemingly ‘appropriate’ baseline correction trials. Although post‐processing of hyperspectral data sets and creating Raman images seem simple, data quality issues such as autofluorescence must be considered. If baseline correction is deemed necessary, it should be addressed as an experiment involving statistical comparison.     

A universal spectral analytical method for digital terrain modeling

There are three major mathematical problems in digital terrain analysis: (1) interpolation of digital elevation models (DEMs); (2) DEM generalization and denoising; and (3) computation of morphometric variables through calculating partial derivatives of elevation. Traditionally, these three problems are solved separately by means of procedures implemented in different methods and algorithms. In this article, we present a universal spectral analytical method based on high-order orthogonal expansions using the Chebyshev polynomials of the first kind with the subsequent Fejér summation. The method is intended for the processing of regularly spaced DEMs within a single framework including DEM global approximation, denoising, generalization, as well as calculating the partial derivatives of elevation and local morphometric variables.

The method is exemplified by a portion of the Great Rift Valley and central Kenyan highlands. A DEM of this territory (the matrix 480 × 481 with a grid spacing of 30″) was extracted from the global DEM SRTM30_PLUS. We evaluated various sets of expansion coefficients (up to 7000) to approximate and reconstruct DEMs with and without the Fejér summation. Digital models of horizontal and vertical curvatures were computed using the first and second partial derivatives of elevation derived from the reconstructed DEMs. To evaluate the approximation accuracy, digital models of residuals (differences between the reconstructed DEMs and the initial one) were calculated. The test results demonstrated that the method is characterized by a good performance (i.e., a distinct monotonic convergence of the approximation) and a high speed of data processing. The method can become an effective alternative to common techniques of DEM processing.     

Genesis of lower strain S-L-type tectonites in Daqingshan area,Inner Mongolia

Usual ductile shear zone has relatively high strain magnitude.However,for high-grade metamorphic rocks in Daqingshan area,the related strain is very low with weakly developed lineation.Significantly,the fi-nite strain type with a K-value slightly lower than 1 and is characterized by compressional strain.Because the special tectonic environment with high temperature,the percentage of melt is relatively higher,which leads to a series of microscopic phenomenon such as multi-grain quartz bands,feldspar three edges equilibrium-like tex-ture,granular flow,etc.As a consequence,the tectonites in the studied area illustrate a unique character:ob-vious rheological meso-deformation structure but with very weak intracrystalline micro-deformation.