Global maps of soil temperature

Research in global change ecology relies heavily on global climatic grids derived from estimates of air temperature in open areas at around 2 m above the ground. These climatic grids do not reflect conditions below vegetation canopies and near the ground surface, where critical ecosystem functions occur and most terrestrial species reside. Here, we provide global maps of soil temperature and bioclimatic variables at a 1-km2 resolution for 0–5 and 5–15 cm soil depth. These maps were created by calculating the difference (i.e. offset) between in situ soil temperature measurements, based on time series from over 1200 1-km2 pixels (summarized from 8519 unique temperature sensors) across all the world\u27s major terrestrial biomes, and coarse-grained air temperature estimates from ERA5-Land (an atmospheric reanalysis by the European Centre for Medium-Range Weather Forecasts). We show that mean annual soil temperature differs markedly from the corresponding gridded air temperature, by up to 10°C (mean = 3.0 ± 2.1°C), with substantial variation across biomes and seasons. Over the year, soils in cold and/or dry biomes are substantially warmer (+3.6 ± 2.3°C) than gridded air temperature, whereas soils in warm and humid environments are on average slightly cooler (−0.7 ± 2.3°C). The observed substantial and biome-specific offsets emphasize that the projected impacts of climate and climate change on near-surface biodiversity and ecosystem functioning are inaccurately assessed when air rather than soil temperature is used, especially in cold environments. The global soil-related bioclimatic variables provided here are an important step forward for any application in ecology and related disciplines. Nevertheless, we highlight the need to fill remaining geographic gaps by collecting more in situ measurements of microclimate conditions to further enhance the spatiotemporal resolution of global soil temperature products for ecological applications

Informační podpora pro velitele zásahu HZS

Import 20/04/2006Prezenční výpůjčkaVŠB - Technická univerzita Ostrava. Fakulta hornicko-geologická. Institut bezpečnostního inženýrství (547

LCF behaviour of 301LN steel: coarse-grained vs. UFG-bimodal structure

Low-cycle fatigue (LCF) behaviour of metastable austenitic 301LN steel with different grain sizes – coarse-grained (14 µm) and UFG (1.4 µm) with a grain bimodality – produced by reversion annealing (RA) was investigated. Symmetrical push-pull LCF tests were conducted on flat sheet specimens at room temperature with constant strain rate of 2×10–3 s–1 and constant total strain amplitude ranging from 0.4% to 0.8%. After completion of fatigue tests a ferritescope was adopted for quantitative assessment of volume fraction of deformation induced martensite (DIM). Microstructural changes, distribution and morphology of DIM in the volume of material were characterized at different scales by colour etching, TEM and EBSD techniques. Experimental data on microstructural changes are confronted with the stress-strain response and with the chemical heterogeneity present in the material

Initial stages of fatigue failure of polycrystalline materials

Geometry of persistent slip markings (PSMs) formed during cyclic loading of polycrystalline stainless steels and superalloy was studied using atomic force microscopy (AFM) and high-resolution scanning electron microscopy (SEM-FEG). Internal dislocation structure was investigated using transmission electron microscopy (TEM). Persistent slip bands with dislocation structure corresponding to the cyclic strain localization were identified and correlated with PSMs observed on the specimen surface

Quantitative assessment of the surface relief in fatigue using AFM

Atomic force microscopy (AFM) was applied to study the early stages of fatigue damage in polycrystalline copper and stainless 316L steel. The analysis of the image formation using an AFM tip reveals the lateral distortion of the extrusions and intrusions in case of high extrusions and deep intrusions. The true extrusion height can be obtained in direct observation and the depth of intrusions using replica technique. The evolution of the shape and the height of extrusions allowed to judge the activity of the persistent slip bands (PSBs) during fatigue life

Influence of mesh density on calculated extreme stresses in aortic aneurysms

The paper deals with evaluation of the influence of finite element mesh density on the resulting extreme stresses in models of abdominal aortic aneurysms. In most patient-specific computationalmodels published recently, a free mesh of tetrahedrons is used and any information on density of the applied mesh is often missing. In this study a comparison of differentmesh densities has been realized with four patient-specificmodel geometries, all based on a numerical reconstruction of the unloaded geometry of the aneurysm, and with two different Yeoh-type constitutive models. It has been shown that resulting maximumstresses are not mesh independent; due to a better description of the stress gradient in the critical location, the maximum wall stress increases with increasing number of elements throughout the wall thickness, especially in models without residual stresses. This effect is more pronouncedwhen using Vande Geest constitutive model with higher strain stiffening than for Raghavan-Vorp material parameters. Although the mesh density requirements were not so high when the stress gradient was reduced by taking residual stresses into consideration, even in this case low numbers of elements throughout the wall thickness may givemesh dependent results. Although for a rigorous recommendation of the mesh density more analyses are needed, it was shown that the time consuming procedure of taking residual stresses into consideration cannot be replaced by a simpler model with rough mesh