O Neolítico Médio Em Portugal: Percurso De Investigação

Neves, César

doi:10.51679/ophiussa.2019.46

Cited by 5 publications

(12 citation statements)

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“…Two possibilities exist for boundary conditions: (a) external electric potential (EEP) boundary condition (constant potential in the bulk surfaces); or (b) average current density (ACD) boundary condition (constant current density in the bulk surfaces). Previous work performed by Neves 35 enabled calibration of the model in accordance with the experimental data for pure iron degradation obtained by Salama et al 20 The ACD boundary conditions were the ones that provide the best fitting between numerical and experimental results.…”

Section: Methodsmentioning

confidence: 82%

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Finite element simulations of mechanical behaviour and degradation of iron lattices

Salama

Alves

Reis

et al. 2022

Proceedings of the Institution of Mechanical Engineers, Part L:

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Biodegradable metals such as iron have become appealing for usage in temporary bone implants. Although iron possesses excellent properties of biocompatibility, it shows a very slow degradation rate and presents a higher stiffness and strength when compared to human bone. Several strategies can be applied to decrease the strength of the iron, one of them being the use of porous/cellular structures. The present work aims to study the mechanical properties and the degradation behaviour of porous iron with cellular structures composed of lattice struts. Six lattice geometries, which were previously studied, and inspired by crystalline structures, were designed. The mechanical behaviour of the lattice arrangements was studied numerically using the finite element software NX Nastran. The corrosion module of the finite element software COMSOL was used to simulate the degradation behaviour of the cellular structure immersed in simulated body fluid. After the degradation process, the compressive properties of the porous cellular structures were also assessed. Under compression, the iron lattice structures showed an elastic limit stress close to the values determined for the trabecular bone yield stress. Geometries selected to simulate degradation have shown mass loss percentage and corrosion rates close to the degradation rate established for an ideal bone substitute. The present study confirms that the structural arrangement has a strong influence on the mechanical properties of iron cellular structures. The degradation behaviour of iron lattices also appears to be affected by the unit cell topology.

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Section: Methodsmentioning

confidence: 82%

“…Table 2 gathers all the parameters obtained by Neves, 35 which were further used in the current work.…”

Section: Methodsmentioning

confidence: 99%

Finite element simulations of mechanical behaviour and degradation of iron lattices

Salama

Alves

Reis

et al. 2022

Proceedings of the Institution of Mechanical Engineers, Part L:

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“…Its cultivation is often controversial. On the one hand, it brings substantial economic benefits to land owners and industry [54,55]. On the other, it often has negative environmental impacts, namely decrease in biodiversity, invasion to contiguous ecosystems (rare and limited), decrease of water and nutrient availability in soil, and increase of fire hazard [54][55][56].…”

Section: Introductionmentioning

confidence: 99%

“…On the one hand, it brings substantial economic benefits to land owners and industry [54,55]. On the other, it often has negative environmental impacts, namely decrease in biodiversity, invasion to contiguous ecosystems (rare and limited), decrease of water and nutrient availability in soil, and increase of fire hazard [54][55][56]. Nevertheless, most of these impacts may be prevented or substantially minimized by proper forest management [54][55][56][57][58].…”

Section: Introductionmentioning

confidence: 99%

“…On the other, it often has negative environmental impacts, namely decrease in biodiversity, invasion to contiguous ecosystems (rare and limited), decrease of water and nutrient availability in soil, and increase of fire hazard [54][55][56]. Nevertheless, most of these impacts may be prevented or substantially minimized by proper forest management [54][55][56][57][58]. Meanwhile, from the perspective of the exotic species, cultivation protects juvenile individuals against environmental stochasticity and preserves founder populations; thus, it may facilitate their naturalization and invasion in the arrival territories [59][60][61].…”

Section: Introductionmentioning

confidence: 99%

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Microsite Drivers of Natural Seed Regeneration of Eucalyptus globulus Labill. in Burnt Plantations

Águas

Matías

Rodrigues

et al. 2022

Forests

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Fire regimes are changing in several regions of the world. In those regions, some exotic species may be better adapted to new regimes than the native species. This study focused on identifying the microsite characteristics associated with the occurrence of post-fire Eucalyptus globulus regeneration from seeds, outside the species native-range. This information is important in helping to assess the naturalization status of the species, to understand its invasion risk, and to manage wildlings in plantations. To characterize the establishment niche, pairs of microsites (sapling presence/absence) were sampled in four salvage-logged plantations of E. globulus two years after fire (20 pairs/plantation). Microsites of wildlings from three size classes and control microsites were established in one of these plantations (20 quartets) in order to characterize the recruitment niche and to assess ontogenic niche shifts. Two post-fire wildling cohorts were identified. The first emerged just after fire and was abundant. The second emerged after logging and was scarce, probably due to seed limitation. First-cohort wildlings were observed in microsites characterized by a high incidence of fire-related variables (charcoal, ash, increased soil pH and K). The aggregated distribution of these wildlings and their association with other species may indicate the existence of facilitative relationships and/or the exploitation of resource-rich patches. All these factors were relevant for first-cohort persistence and likely also for its establishment and recruitment. Second-cohort wildlings occurred in microsites where salvage-logging disturbance was evident, showing the importance of this disturbance for its emergence. Wildling size diversity was explained by the two recruitment events and by the asymmetrical competition between wildlings and adults. No niche shifts were detected. The high densities of E. globulus wildlings found established in burnt plantations indicated naturalization was in progress. The timing of major recruitment events and the phenology of the species should be considered for monitoring this regeneration and scheduling control interventions, if required.

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Exploring the Spatial Relationship between Street Crime Events and the Distribution of Urban Greenspace: The Case of Porto, Portugal

Saraiva,

Teixeira

2023

IJGI

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In post-pandemic, climate-changing societies, the presence of urban greenspace assumes paramount functions, at the same time that socio-economic crises and shocks augment vulnerabilities and insecurities. The recent literature on environmental criminology argues that the geography of crime is not random, and that the presence of greenery, due to its impact on well-being and the environment, can have positive associations with feeling safe; although the opposite effect can occur if spaces are not properly designed or maintained. In this paper, the case study of Porto, Portugal, is presented; one of the municipalities with higher crime rates, that also pledged to double the available greenspace in the near future. As a way to support decision-making, the aim of this study was to present an overall exploratory diagnosis of how street crime patterns, of different typologies, spatially co-exist with greenspaces. Using a 10-year street crime dataset at the segment level, descriptive quantitative methods with the support of GIS have been applied to plot crime’s spatial distribution over time, as well as the walking accessibility to greenspaces. The results confirm crime’s geographical non-randomness, with distinct categories occupying specific locations, even though there was a consistently proportional distribution in the different distance bands. On the contrary, the cumulative effect of the proximity to greenspaces was variable. Almost half of the city’s street crimes (46%) were within a 5 min walking distance of greenspaces, but they were much closer to smaller inner-city urban gardens, with higher densities of street crimes (hot spots), than to larger municipal parks, where lower densities (cold spots) were seen.

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O Neolítico Médio Em Portugal: Percurso De Investigação

Cited by 5 publications

References 0 publications

Finite element simulations of mechanical behaviour and degradation of iron lattices

Finite element simulations of mechanical behaviour and degradation of iron lattices

Microsite Drivers of Natural Seed Regeneration of Eucalyptus globulus Labill. in Burnt Plantations

Exploring the Spatial Relationship between Street Crime Events and the Distribution of Urban Greenspace: The Case of Porto, Portugal

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