COUPLED SIMULATION FOR FIRE-EXPOSED STRUCTURES USING CFD AND THERMO-MECHANICAL MODELS

Fire resistance of buildings is based on fire tests in furnaces with gas burners. However, the tests are very expensive and time consuming. This article presents a coupled simulation of an element loaded by a force and a fire loading. The simulation solves a weakly-coupled problem, consisting of fluid dynamics, heat transfer and mechanical model. The temperature field from the computational fluid dynamics simulation (CFD) creates Cauchy and radiative boundary conditions for the thermal model. Then, the temperature field from element is passed to the mechanical model, which induces thermal strain and modifies material parameters. The fluid dynamics is computed with Fire Dynamics Simulator and the thermo-mechanical task is solved in OOFEM. Both softwares are interconnected with MuPIF python library, which allows smooth data transfer across the different meshes, orchestrating simulations in particular codes, exporting results to the VTK formats and distributed computing

Steel elements with timber fire protection - experiment and numerical analysis

Steel structural elements are sensitive to elevated temperatures, while timber elements have good thermal insulation properties. Timber material can fulfill the role of fire protection of steel members. The effect of the protection is demonstrated on an experiment with three beams with different levels of the protection, placed into a horizontal furnace. The experimental task was also numerically analysed with standard computational approach given by the Eurocode [1, 2], which leads to an interesting comparison, as the calculation is supposed to provide higher temperatures and larger deformations compared to the experimental data

FIRE PROTECTION OF STEEL ELEMENTS USING LIGHTWEIGHT HYBRID CEMENT MORTAR

Material properties of steel structures are significantly reduced at high temperatures, so a fire protection has strong positive impact on the fire resistance of the structure. Fire resistance of steel elements can be increased using a layer of cement-based materials as a fire protection. Most of commonly used cement-based materials do not withstand high temperatures without noticeable reduction of mechanical properties. Hybrid cement showed some interesting properties in the way of resistance to high temperatures and adhesion to steel surfaces, thus its behavior during fire exposure should be investigated. One experimental analysis with numerical simulation is presented in this article. It examines thermal material properties of lightweight hybrid cement mortar with expanded perlite from a simple experiment with a lab gas burner

A WEAK ALKALI BOND IN (N, K)–A–S–H GELS: EVIDENCE FROM LEACHING AND MODELING

The alkali bond in (N, K)–A–S–H gels presents an up-to-date insufficiently resolved issue with significant consequences for efflorescence in alkali-activated materials. A series of experiments shows nearly all alkalis are leachable from alkaliactivated fly-ash and metakaolin in excessive amounts of deionized water. A diffusion-based model describes well the alkali leaching process. Negligible changes of the (N, K)–A–S–H gel nanostructure indicate that Na,K do not form the gel backbone and H3O+ is probably the easiest substitution for the leached alkalies. Small changes in the long-term compressive strength of leached specimens support this hypothesis

The effects of pre- and post-partum depression on child behavior and psychological development from birth to pre-school age : a protocol for a systematic review and meta-analysis

Background: Pre- and post-partum depression is a common mood disorder with detrimental effects on both mother and child. The aim of the proposed review is to summarize evidence related to the effects of both pre- and post-partum depression on child behavior and development from birth to preschool age. In particular, our review will address mutual relations between pre- and post-partum depression in order to determine whether pre- and post-partum depression predict child psychological outcomes independently, whether there is an effect of timing of depression on child outcomes, whether pre- and post-partum depression interact to affect child outcomes, and whether the effect of pre-partum depression is mediated by depression after child's birth. Methods: We will include prospective longitudinal studies that report data about the effects of both pre- and post-partum depression on child psychological outcomes as published in peer-reviewed academic journals since January 1998. We will search EMBASE, MEDLINE, PsycARTICLES, PsycINFO, ISI Web of Science, Scopus, and Wiley Online databases to identify original research articles written in English. Two independent reviewers will screen search results in two stages: (i) titles and abstracts and (ii) full text. The first one will extract data into tables, while the latter will verify whether the data extracted are correct. We will assess the risk of bias in the selected studies using the Critical Appraisal Skills Programme (CASP), Cohort Study Checklist. The results of the review will be reported in a narrative form. If there are sufficient data available, a meta-analysis will be conducted using metaSEM package in R. Discussion: The proposed review will be the first systematic review summarizing the effects of both pre- and post-partum depression on child psychological development and behavior from birth to preschool age. The results of such a review may contribute to a better understanding of mutual relations between pre- and post-partum depression in their effects on child outcomes. They may also shed light on what periods in early human development are most vulnerable to the effects of maternal depression

VALIDATION OF LINKED SIMULATION FOR FIRE-EXPOSED CONCRETE STRUCTURES

This article presents linked computational approach for fire simulation and its effects on structure using adiabatic surface temperature. The simulation solves a weakly-linked problem, consisting of computational fluid dynamics (CFD), heat transport and mechanical model. The temperature field from the CFD creates Cauchy and radiative boundary conditions for the thermal model. The temperature field from an element is passed further to the mechanical model, which induces thermal strain and modifies material parameters. This article also brings a validation of the linked simulation, based on experiment with a concrete block exposed to fire in a furnace. The material model uses standard material properties given in Eurocode 2 - EN 1992-1-2

Spared cognitive processing of visual oddballs despite delayed visual evoked potentials in patient with partial recovery of vision after 53years of blindness

AbstractWe examined the visual and cognitive functions of a 72-year-old subject, KP, who recovered his sight after 53years of visual deprivation. We used visual evoked potentials (VEPs) to pattern-reversal and motion-onset stimuli and cognitive responses (ERPs) during the oddball paradigm to assess the effect of long-term deprivation on a mature visual system. KP lost his sight at the age of 17years, and light projection onto his right retina was restored at 71years by a corneal implant. Nine months after sight recovery we recorded reproducible responses to all examined stimuli. The response to pattern reversal contained two P100-like peaks with the later peak being dominant and significantly delayed (260ms) when compared to the P100s of two control subjects, to whom the stimuli were adjusted in size and contrast to mimic KP’s vision. KP’s motion-onset VEPs to full-field and peripheral stimuli had a characteristic shape with a well-defined N2 peak; however, both peaks were significantly delayed (262 and 272ms) compared to control responses. Unlike the P100 and N2 peaks, which represent sensory detection, the P3b/P300 component of the ERP to a target event in the oddball paradigm was not further delayed. In spite of degraded vision and sensory deprivation lasting 53years, KP displayed reproducible responses to all reported stimuli. Long-term visual deprivation and retinal detachment degraded KP’s visual sensory processing, assessed by pattern-reversal and motion-onset VEPs, whereas the cognitive processing of appropriate visual stimuli was not compromised

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

Rozkład zawartości antymonu i złota w starych osadnikach i hałdach w miejscowości Milešov (powiat Příbram)

DOI nefunkční (17.10.2019)Antimony ores were extracted and processed near the village of Milesov (Pribram district) for about twenty years in the second half of the 19th century. Large heaps and a small sludge pond were left behind after this period. In 1988, this locality was inspected and sampled in order to gather information about residual resources of gold and antimony. The original archive data from this survey were now studied again and interpreted using modern statistical and geostatistical methods. The interpolations methods chosen for this purpose were inverse distance weighting (IDW), simple kriging and geostatistical sequential Gaussian simulation (SGS). These procedures allowed for a much more accurate determination of the spatial distribution of the elements or substances studied. The results showed significantly higher volumes and a more accurate localization of the studied elements in both bodies (heap and tailings). This procedure can be considered as the basis of a new methodology for the assessment of similar objects.Rudy antymonu były wydobywane i przetwarzane w pobliżu wioski Milešov (powiat Příbram) przez około dwadzieścia lat w drugiej połowie XIX wieku. Po tym okresie pozostały duże hałdy i mały staw osadowy. W 1988 r. miejscowość została poddana inspekcji i próbkowaniu w celu zebrania informacji o pozostałościach złota i antymonu. Oryginalne dane archiwalne z tego badania zostały teraz ponownie przeanalizowane i zinterpretowane przy użyciu nowoczesnych metod statystycznych i geostatystycznych. Metody interpolacji wybrane do tego celu to odwrotne ważenie odległości (IDW), prosty kriging i sekwencyjna geostatystyczna symulacja Gaussa (SGS). Procedury te pozwoliły na znacznie dokładniejsze określenie rozkładu przestrzennego badanych pierwiastków lub substancji. Wyniki pokazały znacznie wyższe objętości i dokładniejszą lokalizację badanych pierwiastkach w obu lokalizacjach (hałda i składowisko odpadów). Procedurę tę można uznać za podstawę nowej metodologii oceny podobnych obiektów.Web of Science113413

COUPLED SIMULATION FOR FIRE-EXPOSED STRUCTURES USING CFD AND THERMO-MECHANICAL MODELS

Fire resistance of buildings is based on fire tests in furnaces with gas burners. However, the tests are very expensive and time consuming. This article presents a coupled simulation of an element loaded by a force and a fire loading. The simulation solves a weakly-coupled problem, consisting of fluid dynamics, heat transfer and mechanical model. The temperature field from the computational fluid dynamics simulation (CFD) creates Cauchy and radiative boundary conditions for the thermal model. Then, the temperature field from element is passed to the mechanical model, which induces thermal strain and modifies material parameters. The fluid dynamics is computed with Fire Dynamics Simulator and the thermo-mechanical task is solved in OOFEM. Both softwares are interconnected with MuPIF python library, which allows smooth data transfer across the different meshes, orchestrating simulations in particular codes, exporting results to the VTK formats and distributed computing