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1.
Emelie Axelsson Jonas Pape Jasper Berndt Fernando Corfu Klaus Mezger Michael M. Raith 《Geostandards and Geoanalytical Research》2018,42(3):319-338
A new natural rutile reference material is presented, suitable for U‐Pb dating and Zr‐in‐rutile thermometry by microbeam methods. U‐Pb dating of rutile R632 using laser ablation ICP‐MS with both magnetic sector field and quadrupole instruments as well as isotope dilution‐thermal ionisation mass spectrometry yielded a concordia age of 496 ± 2 Ma. The high U content (> 300 μg g?1) enabled measurement of high‐precision U‐Pb ages despite its young age. The sample was found to have a Zr content of 4294 ± 196 μg g?1, which makes it an excellent complementary reference material for Zr‐in‐rutile thermometry. Individual rutile grains have homogeneous compositions of a number of other trace elements including V, Cr, Fe, Nb, Mo, Sn, Sb, Hf, Ta and W. This newly characterised material significantly expands the range of available rutile reference materials relevant for age and temperature determinations. 相似文献
2.
The capital city of Honduras, Tegucigalpa, suffers from the occurrence of destructive landslides on a yearly basis. During the rainy season, damages to infrastructure as well as injuries, casualties and homeless individuals resulting from landslides are reported in the press. This paper presents the development of a database for rainfall-induced landslides for the period 1980–2005, based on the news reported by two local newspapers. The editions comprehended during the study period have been scrutinized, and articles focusing on landslides, tropical storms, hurricanes, floods and vulnerability of the city have been collected. The interpretation of these archives has allowed the compilation of valuable data of approximately 400 landslides. The analyses of monthly and annual precipitation during the study period show how extreme rainfall events like Hurricane Mitch in October of 1998 have significantly contributed to the initiation of landslides. In addition, the assessment of the slums and neighborhoods affected by landslides during the study period reveals an evident link between the social and physical vulnerability of Tegucigalpa. In order to estimate the reliability of this press-based database, the set of landslides that have been reported as a result of Hurricane Mitch in the press archives has been compared with two inventories based on the interpretation of aerial photographs taken in 1999 and 2001. It is shown that the analysis of the landslide damage left after the hurricane can be enriched with the detailed temporal data provided in the archives and the precise location of these events determined by the aerial photographs. Despite the difficulties faced in the compilation of this database, a good comprehension of the temporal and spatial distribution of landslides in Tegucigalpa has been achieved. 相似文献
3.
The paper presents an optimization routine especially developed for the identification of model parameters in soil plasticity on the basis of different soil tests. Main focus is put on the mathematical aspects and the experience from application of this optimization routine. Mathematically, for the optimization, an objective function and a search strategy are needed. Some alternative expressions for the objective function are formulated. They capture the overall soil behaviour and can be used in a simultaneous optimization against several laboratory tests. Two different search strategies, Rosenbrock's method and the Simplex method, both belonging to the category of direct search methods, are utilized in the routine. Direct search methods have generally proved to be reliable and their relative simplicity make them quite easy to program into workable codes. The Rosenbrock and simplex methods are modified to make the search strategies as efficient and user‐friendly as possible for the type of optimization problem addressed here. Since these search strategies are of a heuristic nature, which makes it difficult (or even impossible) to analyse their performance in a theoretical way, representative optimization examples against both simulated experimental results as well as performed triaxial tests are presented to show the efficiency of the optimization routine. From these examples, it has been concluded that the optimization routine is able to locate a minimum with a good accuracy, fast enough to be a very useful tool for identification of model parameters in soil plasticity. Copyright © 2001 John Wiley & Sons, Ltd. 相似文献
4.
Coupled flow of water, chemicals, heat and electrical potential in soil are of significance in a variety of circumstances. The problem is characterized by the coupling between different flows, i.e. a flow of one type driven by gradients of other types, and by the dual nature of certain flows, i.e. combined convection and conduction. Effective numerical solutions to the problem are challenged due to the coupling and the dual nature. In this paper, we first present a general expression that can be used to represent various types of coupled flows in soil. A finite element method is then proposed to solve the generalized coupled flows of convection-conduction pattern. The unknown vector is first decomposed into two parts, a convective part forming a hyperbolic system and a conductive part forming a parabolic system. At each time step, the hyperbolic system is solved analytically to give an initial solution. To solve the multi-dimensional hyperbolic system, we assume that a common eigenspace exists for the coefficient matrices, so that the system can be uncoupled by transforming the unknown vector to the common eigenspace. The uncoupled system is solved by the method of characteristics. Using the solution of the hyperbolic system as the initial condition, we then solve the parabolic system by a Galerkin finite element method for space discretization and a finite difference scheme for time stepping. The proposed technique can be used for solving multi-dimensional, transient, coupled or simultaneous flows of convection-conduction type. Application to a flow example shows that the technique indeed exhibits optimality in convergence and in stability. 相似文献
5.
Laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) has been applied to determine the elemental composition of the surface layer, as well as of the first interior layer, of quartz grains from the mine tailings from Kristineberg (northern Sweden) in order to determine concentration gradients between these two layers. The quartz grains were collected from the oxidized and unoxidized zones within the tailings. The aim of this study is to assess the role of quartz surfaces as sites for the attenuation of solutes from the mine-tailings porewater. Concentrations of Cu, Ag, Sb, Pb and Bi are highest near the surface of each grain and decrease towards the interior. The surface concentration of Cu, Zn and Pb is more pronounced within the unoxidized than within the oxidized zone of the tailings. Cu exhibits a distinct concentration peak at the surface of the quartz grains below the pre-remediation oxidation front. For Zn and Ce the trend of high surface concentration is less pronounced than for Cu or Pb. Silver, Bi and As are preferably adsorbed within the uppermost layers of the oxidized zone where the pH is as high as 6.2. The conversion of intensity signals of the elements to concentration values in ppm was done by using external standards (NIST silicate glass). 相似文献
6.
The resonant interaction between three acoustic gravity waves is considered. We improve on the results of previous authors and write the new coupling coefficients in a symmetric form. Particular attention is paid to the low-frequency limit. 相似文献
7.
Magnus Axelsson Stefan Larsson Linnea Hjalmarsdotter 《Monthly notices of the Royal Astronomical Society》2009,394(3):1544-1550
We study the soft X-ray variability of Cygnus X-3. By combining data from the All-Sky Monitor and Proportional Counter Array instruments on the RXTE satellite with EXOSAT /Medium Energy (ME) detector observations, we are able to analyse the power density spectrum (PDS) of the source from 10−9 to 0.1 Hz, thus covering time-scales from seconds to years. As the data on the longer time-scales are unevenly sampled, we combine traditional power spectral techniques with simulations to analyse the variability in this range. The PDS at higher frequencies (≳10−3 Hz) are for the first time compared for all states of this source. We find that it is for all states well described by a power law, with index ∼−2 in the soft states and a tendency for a less steep power law in the hard state. At longer time-scales, we study the effect of the state transitions on the PDS, and find that the variability below ∼10−7 Hz is dominated by the transitions. Furthermore, we find no correlation between the length of a high/soft-state episode and the time since the previous high/soft state. On intermediate time-scales, we find evidence for a break in the PDS at time-scales of the order of the orbital period. This may be interpreted as evidence for the existence of a tidal resonance in the accretion disc around the compact object, and constraining the mass ratio to M 2 / M 1 ≲ 0.3 . 相似文献
8.
Paul R. J. Saey Clemens Schlosser Pascal Achim Matthias Auer Anders Axelsson Andreas Becker Xavier Blanchard Guy Brachet Luis Cella Lars-Erik De Geer Martin B. Kalinowski Gilbert Le Petit Jenny Peterson Vladimir Popov Yury Popov Anders Ringbom Hartmut Sartorius Thomas Taffary Matthias Zähringer 《Pure and Applied Geophysics》2010,167(4-5):499-515
Activity concentration data from ambient radioxenon measurements in ground level air, which were carried out in Europe in the framework of the International Noble Gas Experiment (INGE) in support of the development and build-up of a radioxenon monitoring network for the Comprehensive Nuclear-Test-Ban Treaty verification regime are presented and discussed. Six measurement stations provided data from 5 years of measurements performed between 2003 and 2008: Longyearbyen (Spitsbergen, Norway), Stockholm (Sweden), Dubna (Russian Federation), Schauinsland Mountain (Germany), Bruyères-le-Châtel and Marseille (both France). The noble gas systems used within the INGE are designed to continuously measure low concentrations of the four radioxenon isotopes which are most relevant for detection of nuclear explosions: 131mXe, 133mXe, 133Xe and 135Xe with a time resolution less than or equal to 24 h and a minimum detectable concentration of 133Xe less than 1 mBq/m3. This European cluster of six stations is particularly interesting because it is highly influenced by a high density of nuclear power reactors and some radiopharmaceutical production facilities. The activity concentrations at the European INGE stations are studied to characterise the influence of civilian releases, to be able to distinguish them from possible nuclear explosions. It was found that the mean activity concentration of the most frequently detected isotope, 133Xe, was 5–20 mBq/m3 within Central Europe where most nuclear installations are situated (Bruyères-le-Châtel and Schauinsland), 1.4–2.4 mBq/m3 just outside that region (Stockholm, Dubna and Marseille) and 0.2 mBq/m3 in the remote polar station of Spitsbergen. No seasonal trends could be observed from the data. Two interesting events have been examined and their source regions have been identified using atmospheric backtracking methods that deploy Lagrangian particle dispersion modelling and inversion techniques. The results are consistent with known releases of a radiopharmaceutical facility. 相似文献
9.
Reindeer husbandry's strong connection to the land, together with the ongoing climate-change debate, has generated growing interest in its socio-ecological resilience and vulnerability. The ability of indigenous societies and their activities to respond to change is widely recognized to be dependent on several factors, such as socioeconomic forces and aspects of governance, all of which have long historical backgrounds. However, although historians constantly address questions about human societies, there have been very few historical studies on their resilience, vulnerability and adaptation strategies. Here, using historical sources, we analyze the vulnerability of reindeer husbandry (and the Sami societies that depended on it) in Sweden during the 19th century. We demonstrate that although reindeer management was a much more diverse enterprise at that time than it is now, the major adaptation strategy and constraining forces were similar to those of today. The foremost adaptation strategy was, and still is, the flexible use of pasture area, and the clearest constraints during the 19th century were the loss of authority over the land and the imposed regulation of reindeer management-both of which were strongly connected to the process of colonization.
Terminology
Throughout this paper we use the terms reindeer management and reindeer pastoralism interchangeably. Sami reindeer pastoralism has been described as a complex system with two different aspects of management: herding and husbandry. Husbandry has been defined as the accumulations of profit whereas herding has been defined as the control of the animals in the terrain (Paine, 1970, p. 53). In a Swedish context husbandry questions concerning slaughter and castration of reindeer were discussed within the household and herding matters were resolved jointly within the traditional working community Siida. The Siida consisted of households working together on traditional pasturelands and these constellations were grouped together into administrative reindeer pasture districts (Sami villages) ( [Ingold, 1978], [Fellman, 1910] and [Beach, 1981]). 相似文献10.
V. Axelsson 《Geo-Marine Letters》2002,21(4):236-244
Spatial and temporal variations in sedimentation rate and the formation of cyclic and event types of stratification have been identified by the correlation of sedimentation units between sediment cores, which were sampled on the same day during different seasons and years, as well as before and after specific events. Some results are presented from a number of selected areas along the coast of Sweden. The cores were collected in rectangular, transparent coring tubes which were subsequently X-rayed (the uppermost part in stereo) before the cores were extruded from the tubes. The optical data obtained from the radiographic images were then quantified by the use of X-ray densitometric methods. The use of X-ray radiographic techniques, especially stereo-radiography and X-ray densitometry, simplifies the core-to-core correlation as well as the determination of sedimentary properties and the quantification of sedimentation rates. 相似文献