No abstract

Glass fibres slowly degrade due to dissolution when exposed to water. Such environmental aging results in the deterioration of the mechanical properties. In structural offshore and marine applications, as well as in the wind energy sector, R-glass fibre composites are continuously exposed to water and humid environments for decades, with a typical design lifetime being around 25 years or more. During this lifetime, these materials are affected by various temperatures, acidity levels, and mechanical loads. A Dissolving Cylinder Zero-Order Kinetic (DCZOK) model was able to explain the long-term dissolution of R-glass fibres, considering the influence of the pH, temperature, and stress corrosion. The effects of these environmental conditions on the dissolution rate constants and activation energies of dissolution were obtained. Experimentally, dissolution was measured using High Resolution Inductively Coupled Plasma Mass Spectrometry (HR-ICP-MS). For stress corrosion, a custom rig was designed and used. The temperature showed an Arrhenius-type influence on the kinetics, increasing the rate of dissolution exponentially with increasing temperature. In comparison with neutral conditions, basic and acidic aqueous environments showed an increase in the dissolution rates, affecting the lifetime of glass fibres negatively. External loads also increased glass dissolution rates due to stress corrosion. The model was able to capture all of these effects.

No abstract

Extreme climate events are increasingly recognized as a threat to human health, agriculture, forestry and other sectors. To assess the occurrence and impacts of extreme climate events, we have investigated the changes of indexes characterizing positive and negative temperature extremes and extreme precipitation as well as the spatial heterogeneity of extreme climate events in Latvia. Trend analysis of long-term changes in the frequency of extreme climate events demonstrated a significant increase in the number of days with extremely high air temperatures and extreme precipitation, and a decrease in the number extremely cold days.

The urban heat island (UHI) is a phenomenon whereby temperature levels in urban areas are higher than in surrounding rural settings. Urban heat islands are a matter of increasing concern, since they can affect communities by exacerbating air pollution and greenhouse gas emissions (due to the greater use of air conditioning) and the occurrence of heat-related illness, and may lead to higher levels of mortality. This paper provides a description of the phenomena of (UHI) and an analysis of how cities are vulnerable to it. It highlights the need for resilience and the variety of means by which the UHI can be tackled. It describes a set of trends in two regions in Germany and Australia, which illustrate the scope of the problem in the northern and southern hemispheres, and the scale of vulnerability. Then, existing UHI vulnerability assessments are analysed to highlight common features and differences. Based on this, we propose a classification of adaptability parameters to support vulnerability assessments. The paper also discusses current mitigation approaches mentioned in the literature, and how these address some vulnerabilities. It concludes that both a better understanding of the UHI phenomena and consideration of the particular context of each city is needed to make urban areas more resilient to UHI.