浙江省山区综合开发的探讨     

臧威延 《山地学报》1989,(4)

山区综合开发必须调整偏农型产业结构,实行合理利用自然资源和旨在使山区人口向山下流动的积极的社会经济政策,摆脱与分散性密切相关的自给自足观念。由于山区物质、信息流动阻力大,城镇发展宜取多核分散型,要注意交通等基础设施的超前建设,改善山区环境。  相似文献   

Reducing the dimensionality of compositional data sets     

J. Aitchison 《Mathematical Geology》1984,16(6):617-635

The high-dimensionality of many compositional data sets has caused geologists to look for insights into the observed patterns of variability through two dimension-reducing procedures: (i)the selection of a few subcompositions for particular study, and (ii)principal component analysis. After a brief critical review of the unsatisfactory state of current statistical methodology for these two procedures, this paper takes as a starting point for the resolution of persisting difficulties a recent approach to principal component analysis through a new definition of the covariance structure of a composition. This approach is first applied for expository purposes to a small illustrative compositional data set and then to a number of larger published geochemical data sets. The new approach then leads naturally to a method of measuring the extent to which a subcomposition retains the pattern of variability of the whole composition and so provides a criterion for the selection of suitable subcompositions. Such a selection process is illustrated by application to geochemical data sets.  相似文献   

Mean values of particular functions in the elliptic motion     

G. Metris 《Celestial Mechanics and Dynamical Astronomy》1991,52(1):79-84

The mean values % MathType!MTEF!2!1!+-% feaafeart1ev1aaatCvAUfeBSjuyZL2yd9gzLbvyNv2CaerbuLwBLn% hiov2DGi1BTfMBaeXafv3ySLgzGmvETj2BSbqefm0B1jxALjhiov2D% aebbfv3ySLgzGueE0jxyaibaiGc9yrFr0xXdbba91rFfpec8Eeeu0x% Xdbba9frFj0-OqFfea0dXdd9vqaq-JfrVkFHe9pgea0dXdar-Jb9hs% 0dXdbPYxe9vr0-vr0-vqpWqaaeaabiGaciaacaqabeaadaqaaqGaaO% qaamaalaaabaGaaGymaaqaaiaaikdacqaHapaCaaWaa8qCaeaacaGG% OaacbaGaa8NKbiabgkHiTiaadYgacaGGPaGaa8hiaiGacogacaGGVb% Gaai4Caiaa-bcacaWGRbGaa8NKbiaa-bcacaWGKbGaamiBaaWcbaGa% aGimaaqaaiaaikdacqaHapaCa0Gaey4kIipakiaa-bcacaqGHbGaae% OBaiaabsgacaWFGaWaaSaaaeaacaaIXaaabaGaaGOmaiabec8aWbaa% daWdXbqaaiaacIcacaWFsgGaeyOeI0IaamiBaiaacMcacaWFGaGaci% 4CaiaacMgacaGGUbGaa8hiaiaadUgacaWFsgGaa8hiaiaadsgacaWG% SbaaleaacaaIWaaabaGaaGOmaiabec8aWbqdcqGHRiI8aaaa!6BC2!\[\frac{1}{{2\pi }}\int\limits_0^{2\pi } {(f - l) \cos kf dl} {\rm{and}} \frac{1}{{2\pi }}\int\limits_0^{2\pi } {(f - l) \sin kf dl}\] (where f and l are respectively the true anomaly and the mean anomaly in the elliptic motion and k is an integer) are given in closed form.  相似文献   

A new method for the derivation of the closed nets in the phase diagram space of multisystems. I. The absent phase substitution method     

J. Hu  H. Yin  Z. Duan 《Journal of Metamorphic Geology》2004,22(5):413-425

A new convenient combinatorial method is developed here to derive the invariant points in multisystem closed nets – the absent phase substitution (APS) method. It substantially simplifies the derivation of the closed nets in multisystems with many components and phases. For the multisystems whose total phase number (N_PS) ≤ twice the number of the absent phases (m) in an invariant assemblage, the method can yield regular closed nets with or without globally absent phases; for other multisystems, the method can yield the regular closed nets with globally absent phases. As examples, the APS method was used to predict: (1) the regular closed nets of unary to quinary n + 4‐phase multisystems, unary 6‐phase multisystem and ternary 8‐phase multisystem; (2) the basic properties of the regular closed nets of the quaternary and quinary multisystems with n + 4 and n + 5 phases. Two multisystems were chosen to demonstrate how to select a realistic closed net from the numerous possible closed nets of a complex multisystem, and how to derive a realistic partially closed‐net, closed‐net‐diagram and the related realistic straight‐line‐net‐diagram. Comparisons of our APS method for the derivation of complicated closed nets with other methods indicate that this method is much simpler and more efficient.  相似文献   

Trace elements and mineral chemistry of silicified wood from Thailand: colours and elemental distribution     

S. Saminpanya 《Australian Journal of Earth Sciences》2016,63(7):873-884

Thai silicified woods were examined using electron probe microanalysis, yielding chemical data that characterised the samples into two groups: low and high silica contents (82—94 wt% and 94—98 wt%). The elements analysed in order of abundance include Si > Fe > Ca > Na > Al > Ti > K > Mg > Mn > Zr. Iron plays a major role in the colour range (red, orange, yellow, brown, grey and black) of the samples. Calcium is associated with Fe in the darker colours of the wood. Pseudo-crystallochemistry has been used for the substitution of trace elements for Si⁴⁺ in silica polymorphs. The atomic channels that run parallel to the c-axis of silica polymorphs or lattice defects, or even the charge balance for trivalent-ion substitution for Si⁴⁺, can accommodate monovalent ions (K⁺ and Na⁺). Vacant and atomic cavities, which are charged balanced by trivalent ions [Al³⁺ or Fe³⁺ substituting for Si⁴⁺], are commonly occupied by divalent ions (Ca²⁺, Mg²⁺ and Mn²⁺). Quadrivalent ions, Ti⁴⁺ and Zr⁴⁺ are non-structurally incorporated but form clusters of mineral inclusions in the samples. Several other trace-element contents are also in the form of mineral/fluid inclusions hosted in the woods.  相似文献   

Paleoclimatic proxies from global closed basins and the possible beginning of Anthropocene     

LI Yu  HAN Qin  HAO Lu  ZHANG Xinzhong  CHEN Dawei  ZHANG Yuxin  XU Lingmei  YE Wangting  PENG Simin  LI Yichan  FENG Zhuowen  LIU Hebin 《地理学报(英文版)》2021,31(6):765-784

Global closed basins,occupying almost one fifth of the world's land area,spatially coincide with arid and semiarid areas.Paleoclimatic proxies can indicate basin-wide envi-ronmental change and human activity.However,previous studies have not approached the use of proxies in the same way to reconstruct natural and anthropogenic processes at re-gional and global scales.Here we present a regional study to investigate the basic processes of paleoclimatic proxies,from a typical closed-basin system in arid China.We use multiple paleoclimatic proxies of surface samples and sediments,as well as groundwater and sedi-ment ages to study environmental change and human activity.We then establish a dataset for paleoclimatic proxies from global closed basins and do a numerical analysis on it.Regional studies verify that human activity greatly impacts paleoclimatic proxies,especially with regard to surface samples,as well as groundwater age,but Holocene sediments are less affected.Results from global studies indicate that the major changing trend of the wet/dry status of closed basins is associated with the movement of the westerly jet streams controlled by long-term changes in winter insolation.There is an abrupt change between 1800 AD and 1900 AD,according to a numerical synthesis of paleoclimatic proxies from global closed ba-sins,which can be linked to human impact.We suggest this time period can be considered as a start point for the Anthropocene based on the sedimentary evidence of closed basins,globally.  相似文献   

Response of rigid piles during passive dragging     

Wei Dong Guo 《国际地质力学数值与分析法杂志》2016,40(14):1936-1967

This paper develops a three‐layer model and elastic solutions to capture nonlinear response of rigid, passive piles in sliding soil. Elastic solutions are obtained for an equivalent force per unit length p_s of the soil movement. They are repeated for a series of linearly increasing p_s (with depth) to yield the nonlinear response. The parameters underpinning the model are determined against pertinent numerical solutions and model tests on passive free‐head and capped piles. The solutions are presented in non‐dimensional charts and elaborated through three examples. The study reveals the following:

• On‐pile pressure in rotationally restrained, sliding layer reduces by a factor α, which resembles the p‐multiplier for a laterally loaded, capped pile, but for its increase with vertical loading (embankment surcharge), and stiffness of underlying stiff layer: α = 0.25 and 0.6 for a shallow, translating and rotating piles, respectively; α = 0.33–0.5 and 0.8–1.3 for a slide overlying a stiff layer concerning a uniform and a linearly increasing pressure, respectively; and α = 0.5–0.72 for moving clay under embankment loading.
• Ultimate state is well defined using the ratio of passive earth pressure coefficient over that of active earth pressure. The subgrade modulus for a large soil movement may be scaled from model tests.
• The normalised rotational stiffness is equal to 0.1–0.15 for the capped piles, which increases the pile displacement with depth.

The three‐layer model solutions well predict nonlinear response of capped piles subjected to passive loading, which may be used for pertinent design. Copyright © 2016 John Wiley & Sons, Ltd.  相似文献   

GPS动态水汽反演对对流层天顶延迟解算精度分析     

薛骐  熊永良  刘惠涛 《测绘科学》2017,42(1)

针对GPS动态水汽反演过程中对对流层天顶延迟解算精度的评估方法问题,提出了一种利用对流层延迟闭合和附合条件来评估对流层估计精度的方法。通过对PBO观测网中的12个CORS基站以及6个IGS基站的观测数据分析,分别从内符合精度和外符合精度两方面来评估动态对流层解算的精度。在内符合精度的数据处理上,使用事后精密星历,每15s计算一次相对对流层延迟数据。精度满足GPS动态水汽反演对天气预报的基本要求。在外符合精度的数据处理上,使用事后精密星历和超快星历分别对天顶方向对流层延迟进行处理,根据与静态参考值进行比对,两者结果高度吻合。研究结果对GPS动态水汽反演中动态对流层天顶延迟的解算具有重要的参考价值。  相似文献   

内陆湖泊流域的化学风化及气候变化—以内蒙古岱海为例   总被引：3，自引：2，他引：3       下载免费PDF全文

金章东  季俊峰等 《地质论评》2001,47(1):42-46

利用湖泊沉积物中Rb/Sr值来反映受古气候制约的流域陆地化学风化率的变化，并恢复了岱海近400a以来以小冰期为特征的、具有100a准周期（经谱分析）的气候波动历史。通过磁化率、粘土矿物含量和种类的综合分析，确证了湖泊沉积物Rb/Sr值的变化可以用来重建流域内化学风化率与其相应的古气候演化过程，是湖泊沉积记录中具有比磁化率更明显气候意义的有效代用指标。  相似文献   

激光扫描多三维视图的全自动无缝镶嵌   总被引：1，自引：0，他引：1  

张剑清  翟瑞芳  郑顺义 《武汉大学学报(信息科学版)》2007,32(2):100-103

探讨了不同坐标系下的三维点云统一到某一固定坐标系下形成完整目标的问题，提出了一种全自动获取三维视图配准初值的方法。对多三维视图，应用基于闭合条件的整体平差模型，获得最小二乘意义下的最优变换参数，实现了对多三笋视图的全自动无缝镶嵌。利用激光扫描仪的实际扫描数据进行了试验，得到了预期的结果，并验证了本文方法的可行性和有效性。  相似文献