New Perspectives on Water Chemistry and Compositional Data Analysis

Water chemistry is commonly investigated to determine the suitability of water for various uses. With increased knowledge of aqueous chemistry, it has become possible to interpret the evolutionary processes that determine water composition and quality. This paper presents procedures for exploring and modeling the environment using compositional data from water analysis, utilizing statistical tools in an appropriate sample space. Our procedures build on a methodology based on log-ratios initiated by John Aitchison in the early 1980's. They are not only useful for interpreting the structure of the data, but also for characterizing and modeling the influence of geochemical processes acting on the environment. The geochemistry of water samples collected from wells on Vulcano Island (one of the Aeolian Islands of the Italian province of Sicily) will be used to illustrate the techniques, although an exhaustive overview would require many different examples. Vulcano island is a quiescent volcanic area where mobilization of chemical species by weathering of volcanic rocks and input of gaseous components from fumarolic activity has produced environmental changes expressed in the composition of phreatic waters at the surface and in the shallow subsurface. Changes in the chemical composition of waters in unconfined aquifers of the northwestern part of the island around the active crater appear to be useful in understanding the natural processes at work.     

Effect of Initial Principal Stress Direction on the Dynamic Characteristics of Carbonate Sand

INTRODUCTION Theexploitationofoffshorenaturalresourcesin thetropichaspresentedgeotechnicalengineerswith theproblemofdealingwithinsitucarbonatesedi mentsinharshconditionsforwhichfewengineering dataareavailable.Thecarbonatesedimentsaresub jectedtolargestaticstressesduetotheweightof foundationstructuresaswellascyclicstressesdueto waveaction,andinsomecases,earthquakeloading.Ithasbeenprovedthatthenatureofcyclicstresschangesoccurringintheseabeddepositduetowave loadinginvolvesacontinuousrotationo…     

Methods for Setting up a Three-Dimensional Industrial Surveying System of ＂Building Blocks Type＂

This paper is to advance some relevant techniques to set up a three-dimensional industrial surveying system of “building blocks type“, making use of the electronic theodolite, standard ruler and portable computer.     

Using parallel projection mathematics to orient an object relative to a single image

The paper presents a straightforward method of calculating approximate orientation parameters (six degrees of freedom) of a known targeted object relative to a single calibrated camera. These can then initialise an optimised non-linear calculation of the same parameter values. The method uses the mathematics of a scaled parallel projection and is particularly suited to narrow angle images obtained using a telescope, telephoto or zoom lens. However, the method can also be used with cameras having wider fields of view provided the target group occupies a moderately small part of the image.     

Tomographic study of the deep tectonics in the Yecheng-Shiquanhe area of the Tibetan Plateau

The profile crossing the west Kunlun region cov-ers the area between the Tarim Basin and the Kara-korum Fault, which is the highest (~5000 m a.s.l.) andthe most narrow part (400—500 km from north tosouth) of the Tibetan Plateau, thus attracting great at-tention of the geological community because of itsunique tectonic features. The Geological Bureau of Xinjiang Uygur Auton-omous Region and Chinese Academy of Sciences(CAS) carried out mineral exploration and geologicalmapping in th…     

Blending and internal boundary-layer heights, and shear stress

Previous studies of blending heightsfor scalars, using periodic solutions of atmosphericconvection-diffusion equations, raise two questions. 1. What is the relation between growth of the internalboundary-layer height downwind of a step in surfaceconditions, and the increase of blending height withdownwind pattern wavelength? 2. Can the approach beextended to shear stress? The answers are: 1. Thedependence of boundary-layer height on fetch has thesame functional form as that of blending height onwavelength; but it is greater by a factor of about1.9. 2. Representing eddy diffusivity as the productof mean windspeed and a power of height gives a linearhorizontal momentum equation. A further approximationgives a convection-diffusion equation for shearstress, analogous to those used previously forscalars.     

Sensitivities of seismic traveltimes and amplitudes in reflection tomography

Seismic traveltimes and amplitudes in reflection-seismic data show different dependences on the geometry of reflection interfaces, and on the variation of interval velocities. These dependences are revealed by eigenanalysis of the Hessian matrix, defined in terms of the Fréchet matrix and its adjoint associated with different norms chosen in the model space. The eigenvectors and eigenvalues of the Hessian clearly show that for reflection tomographic inversion, traveltime and amplitude data contain complementary information. Both for reflector-geometry and for interval-velocity variations, the traveltimes are sensitive to the model components with small wavenumbers, whereas the amplitudes are more sensitive to the components with high wavenumbers. The model resolution matrices, after the rejection of eigenvectors corresponding to small eigenvalues, give us some insight into how the addition of amplitude information could potentially contribute to the recovery of physical parameters.
In order to cooperatively invert seismic traveltimes and amplitudes simultaneously, we propose an empirical definition of the data covariance matrix which balances the relative sensitivities of different types of data. We investigate the cooperative use of both data types for, separately, interface-geometry and 2-D interval-velocity variations. In both cases we find that cooperative inversions can provide better solutions than those using traveltimes alone. The potential benefit of including amplitude-data constraints in seismic-reflection traveltime tomography is therefore that it may be possible to resolve the known ambiguity between the reflector-depth uncertainty and the interval-velocity uncertainty better.     

岩体强度的各向异性研究

本文运用断裂力学理论推导了含节理岩体的初裂强度公式,定量地讨论了节理方向、长度对岩石强度的影响,阐明了节理岩体强度各向异性的实质。通过证实,本文所建立的公式具有很强的适用性和较高的可靠性,可用于实际的工程岩体稳定性评价。     

中国花岗岩锶同位素组成的基本特点及研究意义

统计表明,我国花岗岩呈锶同位素组成,以秦岭—大别山造山带为界,南北呈现明显的差别。北方地区的花岗岩初始锶同位素比值90％的数据小于0.710,伴生的主要成矿元素为上地幔中富含亲铁性和亲硫性较强的元素,花岗岩的物质来源较深。南方花岗岩初始锶同位素比值80％的数据大于0.710,伴生的主要成矿元素为在地壳硅铝质岩石中富集的亲石性元素,花岗岩的物质来源较浅。