Evaluation and suggestions for improvement of seismic design procedures for R/C walls in dual systems

This paper aims to shed some further light on the seismic behaviour and design of reinforced concrete (R/C) walls which form part of dual (frame + wall) structures. The significance of post‐elastic dynamic effects is recognized by most seismic codes in the definition of the design action effects on walls, i.e. bending moments and shear forces. However, the resulting envelopes are not always fully satisfactory, particularly in the case of medium‐to‐high‐rise buildings. The relevant provisions of modern seismic codes are first summarized and their limitations discussed. Then an extensive parametric study is presented which involves typical multi‐storey dual systems that include walls with unequal lengths, designed according to the provisions of Eurocode 8 for two different ductility classes (M and H) and two effective peak ground acceleration levels (0.16 and 0.24g). The walls of these structures are also designed according to other methods, such as those used in New Zealand and Greece. The resulting different designs are then assessed by subjecting the structures to a suite of records from strong ground motions, carrying out inelastic time history analysis, and comparing the results with the design action effects. It is found that for (at least) the design earthquake intensity, the first two modes of vibration suffice for describing the seismic response of the walls. The bending moment envelope, as well as the base shear of each wall, is found to be strongly dependent on the second mode effect. As far as the code‐prescribed design action effects are concerned, only the NZ Code was found to be consistently conservative, whereas this was not always the case with EC8. A new method is then proposed which focuses on quantifying in a simple way the second mode effects in the inelastic response of the walls. This procedure seems to work better than the others evaluated herein. Copyright © 2010 John Wiley & Sons, Ltd.     

Understanding and Modelling Rapid Dynamic Changes of Tidewater Outlet Glaciers: Issues and Implications

Recent dramatic acceleration, thinning and retreat of tidewater outlet glaciers in Greenland raises concern regarding their contribution to future sea-level rise. These dynamic changes seem to be parallel to oceanic and climatic warming but the linking mechanisms and forcings are poorly understood and, furthermore, large-scale ice sheet models are currently unable to realistically simulate such changes which provides a major limitation in our ability to predict dynamic mass losses. In this paper we apply a specifically designed numerical flowband model to Jakobshavn Isbrae (JIB), a major marine outlet glacier of the Greenland ice sheet, and we explore and discuss the basic concepts and emerging issues in our understanding and modelling ability of the dynamics of tidewater outlet glaciers. The modelling demonstrates that enhanced ocean melt is able to trigger the observed dynamic changes of JIB but it heavily relies on the feedback between calving and terminus retreat and therefore the loss of buttressing. Through the same feedback, other forcings such as reduced winter sea-ice duration can produce similar rapid retreat. This highlights the need for a robust representation of the calving process and for improvements in the understanding and implementation of forcings at the marine boundary in predictive ice sheet models. Furthermore, the modelling uncovers high sensitivity and rapid adjustment of marine outlet glaciers to perturbations at their marine boundary implying that care should be taken in interpreting or extrapolating such rapid dynamic changes as recently observed in Greenland.     

Distribution and speciation of gold in biogenic and abiogenic calcium carbonates - Implications for the formation of gold anomalous calcrete

Calcrete (pedogenic Ca carbonate) is an important sampling medium for geochemical gold (Au) exploration in semi-arid and arid regions of Australia, because it is widespread, easy to sample and calcium (Ca) shows a strong positive correlation with Au, but not with base metals, in calcrete overlying buried Au mineralization. In this study we show that the formation of Au-anomalous calcrete can be biomediated through the activity of resident microorganisms, and may not simply be the result of passive nucleation on inactive cells or evapotransporative processes. Calcified microfossils are highly abundant in calcrete from the Barns Au-prospect in South Australia. These microfossils are morphological analogues of calcified cells and biofilms formed in laboratory experiments conducted with active bacterial cultures enriched from Au-anomalous calcareous sand from the Barns prospect. Calcium carbonates precipitated by these cultures consisted mostly of calcite, which is the main carbonate mineral in calcrete. Synchrotron micro-X-ray fluorescence (S-μXRF) mapping was used to assess the distribution of Au, Zn, Ca and other metals in Ca carbonates precipitated by active bacterial cultures. On a μm-scale the distribution of Au was heterogeneous in these Ca carbonates and differed from base metal distribution, thus mimicking the spatial separation of these metals observed in calcrete. The speciation of Au in Ca carbonates precipitated by active bacteria was measured using micro-X-ray absorption near edge structure spectroscopy (μ-XANES) and resembled that observed in Au-anomalous calcrete closely. While metallic Au was observed in Au ‘hotpots’, ionic Au was detected in the halo surrounding the ‘hotspot’. In contrast, the precipitates produced in the presence of dead bacterial cells or by raising solution pH or pCO₂, i.e., hydroxylapatite, portlandite and vaterite, respectively, did not reflect the mineralogy of calcrete. Gold distribution and speciation in vaterite, formed by raising pCO₂, were homogenous and did not reproduce the variation observed in calcrete and Ca carbonates precipitated by active cells. Increasing the supersaturation with respect to Ca in solution by incremental drying of the medium produced only X-ray amorphous precipitates, or hydroxylapatite in the presence heat-killed cells. In conclusion, this study shows that active microbial processes that combine biogenic Ca carbonatogenesis with Au precipitation are likely to drive the formation of Au-anomalous calcrete.     

Human biometeorological evaluation of heat-related mortality in Vienna

The relationship between heat stress and mortality in the federal state of Vienna (Austria) was analyzed from 1970 to 2007. Long-term trends of mortality data and short-term adaptation to heat stress were considered by two complex approaches. The evaluation is based on the human biometeorological parameter, physiologically equivalent temperature. The results revealed a significant impact of heat stress on the human health, with a significantly higher sensitivity on women compared to men. Additionally, higher risks of deaths due to cardiovascular and respiratory diseases were found. During the long period of 38?years, some significant decreases of the sensitivity were found, especially in the medium heat stress levels. This could indicate active processes of long-term adaptation to the increasing heat stress.     

Analysis of high-resolution simulations for the Black Forest region from a point of view of tourism climatology �C a comparison between two regional climate models (REMO and CLM)

An analysis of climate simulations from a point of view of tourism climatology based on two regional climate models, namely REMO and CLM, was performed for a regional domain in the southwest of Germany, the Black Forest region, for two time frames, 1971?C2000 that represents the twentieth century climate and 2021?C2050 that represents the future climate. In that context, the Intergovernmental Panel on Climate Change (IPCC) scenarios A1B and B1 are used. The analysis focuses on human-biometeorological and applied climatologic issues, especially for tourism purposes ?C that means parameters belonging to thermal (physiologically equivalent temperature, PET), physical (precipitation, snow, wind), and aesthetic (fog, cloud cover) facets of climate in tourism. In general, both models reveal similar trends, but differ in their extent. The trend of thermal comfort is contradicting: it tends to decrease in REMO, while it shows a slight increase in CLM. Moreover, REMO reveals a wider range of future climate trends than CLM, especially for sunshine, dry days, and heat stress. Both models are driven by the same global coupled atmosphere?Cocean model ECHAM5/MPI-OM. Because both models are not able to resolve meso- and micro-scale processes such as cloud microphysics, differences between model results and discrepancies in the development of even those parameters (e.g., cloud formation and cover) are due to different model parameterization and formulation. Climatic changes expected by 2050 are small compared to 2100, but may have major impacts on tourism as for example, snow cover and its duration are highly vulnerable to a warmer climate directly affecting tourism in winter. Beyond indirect impacts are of high relevance as they influence tourism as well. Thus, changes in climate, natural environment, demography, tourists?? demands, among other things affect economy in general. The analysis of the CLM results and its comparison with the REMO results complete the analysis performed within the project Climate Trends and Sustainable Development of Tourism in Coastal and Low Mountain Range Regions (CAST) funded by the German Federal Ministry of Education and Research (BMBF).     

The opposing effects of climate change and socio-economic development on the global distribution of malaria

The current global geographic distribution of malaria results from a complex interaction between climatic and non-climatic factors. Over the past century, socio-economic development and public health measures have contributed to a marked contraction in the distribution of malaria. Previous assessments of the potential impact of global changes on malaria have not quantified the effects of non-climate factors. In this paper, we describe an empirical model of the past, present and future-potential geographic distribution of malaria which incorporates both the effects of climate change and of socio-economic development. A logistic regression model using temperature, precipitation and gross domestic product per capita (GDPpc) identifies the recent global geographic distribution of malaria with high accuracy (sensitivity 85% and specificity 95%). Empirically, climate factors have a substantial effect on malaria transmission in countries where GDPpc is currently less than US$20,000. Using projections of future climate, GDPpc and population consistent with the IPCC A1B scenario, we estimate the potential future population living in areas where malaria can be transmitted in 2030 and 2050. In 2050, the projected population at risk is approximately 5.2 billion when considering climatic effects only, 1.95 billion when considering the combined effects of GDP and climate, and 1.74 billion when considering GDP effects only. Under the A1B scenario, we project that climate change has much weaker effects on malaria than GDPpc increase. This outcome is, however, dependent on optimistic estimates of continued socioeconomic development. Even then, climate change has important effects on the projected distribution of malaria, leading to an increase of over 200 million in the projected population at risk.     

Atmospheric circulation variability in Europe and northern Asia (1901 to 2010)

Climate variability in Europe and northern Asia is markedly affected by changes in atmospheric circulation. Two manual catalogues of large-scale circulation patterns, the ‘Grosswetterlagen’ (GWLc) and ‘Vangengeim-Girs’ classifications (VGc), were analysed and compared to detect frequency changes of circulation forms. Results were compared with variations of ‘objective’ references: variations of the North Atlantic Oscillation (NAO) and a hybrid version of the GWLc (SynopVis Grosswetterlagen catalogue, SVGc). Changes were investigated for 1901–2010, focussing on the most recent climate normal (1981–2010). Trends are moderate in the winter half year (WHY), but rather consistent between the approaches. Circulation variability within VGc/NAO and GWLc/SVGc largely agrees. In the summer half year, large trends are visible in VGc and GWLc, but their objective support by the SVGc, showing comparably small changes, is low. Changes in the distribution of circulation patterns likely fostered a larger temperature increase in the investigated regions compared to global average temperatures during the past 30 years in the WHY. The results of this study help further in investigating temperature and precipitation changes in both Europe and northern Asia.     

Assessment of thermal bioclimate and tourism climate potential for central Europe—the example of Luxembourg

Tourism destinations often require information about climate to assess their climate potential. This can be performed in terms of mean conditions of relevant climatological parameters. For a user-friendly analysis and visualization of climate data relevant for tourism application in Luxembourg, information is prepared based on the facets of climate in tourism. Information on thermal comfort/stress conditions as well as aesthetical and physical parameters is considered. In the present study, relevant and sensible factors were identified and presented. Therefore, physiologically equivalent temperature, precipitation patterns and the Climate-Tourism/Transfer-Information-Scheme are applied. In addition, extreme events relevant for heat stress are analysed based on existing data sets (i.e. heat waves of 2010). Expected climatic conditions for the future are investigated using the projections of two different regional climate models. The results concerning climate change conditions reveal increasing heat stress and sultriness but decreasing cold stress. This information is the basis for an adequate assessment to provide relevant information for different environmental planning issues as well as for the growing tourism sector of Luxembourg.     

Characterization of regional hydrological drought using improved precipitation records under multi-auxiliary information

Theoretical and Applied Climatology - Drought is a complex natural hazard that has been recurrently occurred in many regions across the globe. Therefore, precise drought characterization and its...     

Planetary scientific target detection via deep learning: A case study for finding shatter cones in Mars rover images

Past, present, and forthcoming planetary rover missions to Mars and other planetary bodies are equipped with a large number of scientific cameras. The very large number of images resulting from this, combined with tight time constraints for navigation, measurements, and analyses, pose a major challenge for the mission teams in terms of scientific target evaluation. Shatter cones are the only macroscopic evidence for impact-induced shock metamorphism and therefore impact craters on Earth. The typical features of shatter cones, such as striations and horsetail structures, are particularly suitable for machine learning methods. The necessary training images do not exist for such a case; therefore, we pursued the approach of producing them artificially. Using PRo3D, a viewer developed for the interactive exploration and geologic analysis of high-resolution planetary surface reconstructions, we virtually placed shatter cones in 3-D background scenes processed from true Mars rover imagery. We use PRo3D-rendered images of such scenes as training data for machine learning architectures. Terrestrial analog studies in Ethiopia supported our lab work and were used to test the resulting neural network of this feasibility study. The result showed that our approach with shatter cones in artificial Mars rover scenes is suitable to train neural networks for automatic detection of shatter cones. In addition, we have identified several aspects that can be used to improve the training of the neural network and increase the recognition rate. For example, using background data with a higher resolution in order to have equal resolution of object (shatter cone) and Martian background and increase the number of objects that can be placed in the training data set. Also using better lighting reconstructions and a better radiometric adaption between object and Martian background would further improve the results.