柴达木盆地西台吉乃尔盐湖沉积的年代学研究

柴达木盆地中部西台吉乃尔盐湖成因及其年代框架还存在争议。通过应用光释光测年法（OSL）和放射性碳测年法（AMS¹⁴C）测定两支分别来自该盐湖中部及东部边缘区域的岩芯,获得4个OSL和5个AMS¹⁴C年代数据。结果表明：（1） 对于老于30 ka的样品放射性碳测年法存在明显的年代低估,而对于年轻样品则存在约4.0 ka的碳库效应,相对而言光释光测年方法具有一定的合理性。（2） 两支岩芯顶部粉砂质粘土层形成于约0.3 ka,中部含粉砂质粘土盐层形成于大约4.0 ka,底部粉砂质粘土层则至少形成于70 ka 之前。     

Characterization of groundwater quality in Kinmen Island using multivariate analysis and geochemical modelling

Kinmen is located in the south‐west of Mainland China and mainly has two islands, Large Kinmen and Leiyu. Residents in Kinmen have drunk groundwater over several decades. This work characterized the quality of groundwater in Kinmen using factor analysis (FA), cluster analysis (CA) and geochemical simulation. The factor scores were plotted spatially to illustrate the groundwater quality and were used to discuss the grouped relationship using CA. Salinization, redox and organic matter factors are identified from 17 hydrochemical measurements in 18 wells. Acidic and oxidizing groundwater with nitrate‐N pollution is distributed mainly in the west of Large Kinmen. Saline groundwater is distributed to the north‐east of Large Kinmen and in the south of Leiyu. Groundwater with organic matter is present throughout Leiyu. Five groups of the groundwater quality divided by CA can be interpreted according to one to three factors. The grouped characteristics of the groundwater quality help the local government and industries to plan the use and protection of groundwater resources. Furthermore, a geochemical simulation was used to demonstrate the formation processes of the acidic and oxidizing groundwater properties in granitic sediments. A large amount of the precipitation of the kaolinite and magnetite releases concentrations of hydrogen ion and raises the redox potential in the aquifers. Copyright © 2007 John Wiley & Sons, Ltd.     

Cross-border regional development in Southern China

Cross-border zones have been developed rapidly in China since 1979. This was largely due to the global economic restructuring in the post-Fordist era. The enclave of Hong Kong plays an indispensable role in the process. While China adopts the Open Door Policy, factories in Hong Kong are quick to relocate to the Pearl River Delta region in order to benefit from the low production costs and other preferential policies. The paper first reviews the factors leading to the economic integration between Hong Kong and the Pearl River Delta region of southern China. It then examines the sectoral changes and the socio-economic data of the region. Rapid urbanization and rural urbanization are reflected in the quest for infrastructural development plans and the loss of quality farmland. They also bring along environmental hazards. The paper concludes with the call for a comprehensive development strategy for the region into the next century. This revised version was published online in August 2006 with corrections to the Cover Date.     

Planetary dynamos: effects of electrically conducting flows overlying turbulent regions of magnetic field generation

A fully three-dimensional, nonlinear, time-dependent, multi-layered spherical kinematic dynamo model is used to study the effect on the observable external magnetic field of flow in an electrically conducting layer above a spherical turbulent dynamo region in which the α effect generates the magnetic field. It is shown that the amplitude and structure of an observable planetary magnetic field are largely determined by the magnitude and structure of the flow in the overlying layer. It is also shown that a strong-field planetary dynamo can be readily produced by the effect of an electrically conducting flow layer at the top of a convective core. The overlying layer and the underlying convective region constitute a magnetically strongly coupled system. Such overlying layers might exist at the top of the Earth's core due to chemical or thermal causes, in the cores of other terrestrial planets for similar reasons, and in Saturn due to the differentiation of helium from hydrogen. An electrically conducting and differentially rotating layer could exist above the metallic hydrogen region in Jupiter and affect the jovian magnetic field similar to the overlying layers in other planets. Lateral temperature gradients resulting in thermal winds drive the flow in the overlying layers. All planetary magnetic fields could be maintained by similar turbulent convective dynamos in the field-generation regions of planets with the differences among observable magnetic fields due to different circulations in the overlying electrically conducting layers.     

南海北部海面风速概率分布特征

利用南海北部的浮标、石油平台观测的海面风资料,分析了0~200 km范围内,不同离岸距离站点的风速的概率分布特征。观测结果指出,各站平均风速一般最大值出现在冬季,最小值出现在夏季,具有明显的季节变化特征,并且平均风速随着离岸距离的增大也逐渐增大。对于离岸距离较近的区域（100 km以内）,海面风基本符合双参数的Weibull分布,但对于100 km以外的海面风速概率分布与Weibull分布存在明显差异,随着离岸距离的增大,平均风速和风速标准偏差也相应增大。风速平均值与风速标准偏差的比值较小时,Weibull分布的偏斜度基本为正值,当比值较大时偏斜度转为负值。随着离岸距离的增大,出现与Weibull分布不一致的情况越来越多,且与对应的Weibull分布相比,其偏斜度越小,风速概率分布越不能用Weibull分布进行较好拟合。     

Interannual and Interdecadal Variability of Winter Precipitation over China in Relation to Global Sea Level Pressure Anomalies

Based on the method of rotated principal component (RPC) analysis and wavelet transforms, the win-ter precipitation from 36 stations over China for the period 1881-1993 is examined. The results show thatthe three leading space-time modes correspond, in sequence, to winter rainfall anomalies over the reaches ofthe Yangtze River, the bend of the Yellow River, and the northeastern region of China. The three modes ex-hibit interannual oscillations with quasi-biennial and 8-year periods as well as interdecadal oscillationswith 16- and 32-year periods. The interannual oscillation (＜ 10 years) occurs in phase over the differentareas, and its maximum amplitude migrates northward considerably with prominent interdecadal variations.However, the interdecadal oscillations (10-32 years) are out of phase over the different regions, and theamplitude variations have the characteristics of stationary waves.The rainfall anomalies appear to be closely re lated to the anti-phase changes of mean sea-level pres-sure (SLP) over the Asian mainland and the North Pacific. When the SLP rises over the North Pacific anddecreases over the Asian mainland, the precipitation over East China increases noticeably. The linkage be-tween the rainfall over China and the SLP anomalies apparently results from the strength of the East Asianwinter monsoon and its associated temperature and moisture advection.     

Optimal design and impact analysis of urban traffic regulations under ambient uncertainty

Decision-making in traffic regulations is challenging with uncertainty in the environment. In this research we extend probabilistic engineering design concepts to policy decision-making for urban traffic with variability from field data. City traffic is simulated using user equilibrium and cellular automata. A cellular automata (CA) model is developed by combing existing CA models with tailored rules for local traffic behaviors in Tainan, Taiwan. Both passenger sedans and motorcycles are considered with the possibility of passing between different types of vehicles. The tailpipe emissions from all mobile sources are modeled as Gaussian dispersion with finite line sources. Speed limits of all roads are selected as independent policy design variables, resulting in a problem with 50 dimensions. We first study the impacts of a particular policy-setting on traffic behaviors and on the environment under various sources of uncertainties. The genetic algorithm, combined with probabilistic analysis, is then used to obtain the optimal regulations with the minimal cost to the environment in compliance to the current ambient air quality standards.     

Approach to complete limit equilibrium analysis for rock wedges — the method of “artificial supports”

SummaryApproach to Complete Limit Equilibrium Analysis for Rock Wedges — The Method of Artificial Supports Since the movement of rock wedges or blocks is the primary phenomenon in rock mass failure, it is convenient to use limit equilibrium approaches for stability analysis. In spite of their wide use, limit equilibrium analysis is often restricted due to: 1) the usual procedural simplifications (regarding geometry, force application, failure modes), and 2) basic deficiencies of the limit equilibrium approach (the fundamentally indeterminate rigid body problem requires assumptions regarding the force reactions). The method of artificial supports intends to circumvent or reduce many of these restrictions. In particular, the problem of unknown force distribution on the supporting plane is reduced by specifically considering and optimizing a variety of reactions on these planes. All sliding modes of failure — i. e., translational, free and restrained rotational sliding — can be correctly modelled. Particularly significant is the result that the usual assumption oftranslational sliding can be incorrect andunsafe, if forces other than the weight are significant. The methodologies employed in the artificial support model can be extended to all modes of failure, i. e., lifting off and toppling in addition to the previously mentioned sliding modes; this is demonstrated with a procedure for a complete stability analysis for a 2-joint wedge.

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ZusammenfassungEin Weg zur vollständigen Gleichgewichtsberechnung für Felskörper — Die Methode der Künstlichen Auflager Da die Bewegung von Einzelblöcken das primäre Phänomen bei Felsstürzen ist, eignen sich Grenzgleichgewichtsbetrachtungen besonders gut für Stabilitätsuntersuchungen. Vor allem wegen der üblichen Vereinfachungen (Geometrie, Kräfteansätze, Versagensmechanismen) und grundlegender Unzulänglichkeiten (das grundsätzlich statisch unbestimmte Starrkörperproblem erfordert Annahmen bezüglich der Auflagerkräfte) sind solche Grenzgleichgewichtsbetrachtungen oft nur beschränkt anwendbar, obwohl sie häufig angewendet werden. Es wird versucht, mit der Methode der künstlichen Auflager viele dieser Einschränkungen zu umgehen. Vor allem wird das Problem der unbekannten Spannungsverteilung in den Auflageflächen dadurch reduziert, daß mögliche Kombinationen solcher Reaktionen in die Rechnung einbezogen und optimiert werden. Alle Gleitbewegungen, seien es Translationen oder freie bzw. beschränkte Rotationen auf den Auflageflächen, können korrekt behandelt werden. Besondere Bedeutung kommt aber der Tatsache zu, daß die übliche Annahme einer translatorischen Gleitung falsch ist bzw. daß man damit auf der unsicheren Seite liegt, wenn außer dem Eigengewicht noch andere Kräfte einwirken.Die Überlegungen, die der Modellvorstellung der künstlichen Auflager zugrunde gelegt wurden, können auf alle Instabilitätsfälle ausgedehnt werden, also auch auf Abheben und Kippen zusätzlich zu den vorhin genannten Gleitbewegungen; dies wird am Beispiel einer Rechenprozedur für eine vollständige Stabilitätsuntersuchung eines Gleitkeils gezeigt.

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RésuméTentative visant à compléter l'analyse par équilibre limite — la méthode des supports artificiels Le fait que le déplacement de blocs est le principal phénomène d'instabilité en massif rocheux suggère l'utilisation de méthodes d'équilibre limite à l'étude de sa stabilité. Bien qu'elles soient fréquemment utilisées, les analyses par équilibre limite sont souvent restreintes par suite 1) de simplifications opérationnelles (concernant la géométrie, les forces et les modes d'instabilité), et 2) des insuffisances fondamentales de cette approche (le problème des corps indéformables est en essence statiquement indéterminé et réclame en conséquence l'adoption d'hypothèses sur la teneur des réactions).L'intention de la méthode des supports artificiels est de réduire ou éviter plusieures de ces restrictions. En particulier le problème de la distribution inconnue des forces sur le plan d'assise est résolu en considérant et optimisant un certain nombre de réactions entre corps rigide et le plan de base. Tous les modes d'instabilité au glissement — à savoir translation, rotation restreinte et rotation libre — peuvent être correctement représentés. Spécialement digne d'intérêt est à cet égard le résultat concernant l'habituelle hypothèse de glissement en translation, puisque celui-ci peut s'avérer incorrect et exhiber des facteurs de sécurité supérieurs, par rapport à un glissement en rotation, lorsque des forces autres que le poids sont à considérer.La méthodologie servant de base à la méthode des supports artificiels peut être étendue à tous modes d'instabilité, à savoir: le soulèvement et le renversement venant compléter ceux précités; ceci est illustré par le développement d'une procédure d'analyse complète d'un bloc monolithique découpé par deux fissures.

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With 13 Figures     

Radium and barium at GEOSECS stations in the Atlantic and Pacific

²²⁶Ra and Ba show a general linear correlation in the oceanic water column within the uncertainties of the data: the slope of the line is about 4.6 nanomoles (nmoles) Ra/mole Ba, the intercept being at about 4 nmoles Ba/kg. This demonstrates the usefulness of Ba as a “chemical analogue” of Ra. Box-model calculations indicate that the average deep-water excess of Ra over Ba should be about 10% relative to the surface. This is consistent with the observations outside the deep northeast Pacific. However, the uncertainties in the data are such that the regional variation in the primary input cannot be resolved. In the deep waters of the North Pacific there is in fact a large excess of Ra relative to Ba. The one detailed profile presently available (204) can be explained consistently by a simple vertical advection-diffusion model.