Evaluation of Deformable Boundary Condition Using Finite Element Method and Impact Test for Steel Tubes

Stainless steel pipelines are crucial components to transportation and storage in the oil and gas industry. However, the rise of random attacks and vandalism on these pipes for their valuable transport has led to more security and protection for incoming surface impacts. These surface impacts can lead to large global deformations of the pipe and place the pipe under strain, causing the eventual failure of the pipeline. Therefore, understanding how these surface impact loads affect the pipes is vital to improving the pipes’ security and protection. In this study, experimental test and finite element analysis (FEA) have been carried out on EN3B stainless steel specimens to study the impact behaviour. Low velocity impact tests at 9 m/s with 16 kg dome impactor was used to simulate for high momentum impact for localised failure. FEA models of clamped and deformable boundaries were modelled to study the effect of the boundaries on the pipes impact behaviour on its impact resistance, using experimental and FEA approach. Comparison of experimental and FE simulation shows good correlation to the deformable boundaries in order to validate the robustness of the FE model to be implemented in pipe models with complex anisotropic structure

Impacts of climate change on national biodiversity population trends

Climate change has had well-documented impacts on the distribution and phenology of species across many taxa, but impacts on species’ abundance, which relates closely to extinction risk and ecosystem function, have not been assessed across taxa. In the most comprehensive multi-taxa comparison to date, we modelled variation in national population indices of 501 mammal, bird, aphid, butterfly and moth species as a function of annual variation in weather variables, which through time allowed us to identify a component of species’ population growth that can be associated with post-1970s climate trends. We found evidence that these climate trends have significantly affected population trends of 15.8% of species, including eight with extreme (> 30% decline per decade) negative trends consistent with detrimental impacts of climate change. The modelled effect of climate change could explain 48% of the significant across-species population decline in moths and 63% of the population increase in winged aphids. The other taxa did not have significant across-species population trends or consistent climate change responses. Population declines in species of conservation concern were linked to both climatic and non-climatic factors respectively accounting for 42 and 58% of the decline. Evident differential impacts of climate change between trophic levels may signal the potential for future ecosystem disruption. Climate change has therefore already driven large-scale population changes of some species, had significant impacts on the overall abundance of some key invertebrate groups and may already have altered biological communities and ecosystems in Great Britain

Impacts of climate change on national biodiversity population trends

Lepidoptera are sensitive to climate change, with documented impacts on their phenology, distribution and communities. However, there remains considerable uncertainty over which species are most vulnerable, and which have been most affected so far. To address this, we analyse 35-year UK or English population trends of 55 butterfly and 265 moth species to model the impacts of variation in temperature and precipitation upon population growth rates. We identify the weather variables and periods that species are most sensitive to, the long-term impacts of climate change, and the characteristics of species which show the greatest responses. Positive impacts of summer temperature on both butterflies and moths were partly offset by negative impacts of temperature in other seasons, particularly winter. Precipitation tended to have negative impacts on population growth rates, particularly for moths. Annual population fluctuations were strongly driven by inter-annual variation in weather conditions. Over 40% of a significant decline in mean moth abundance from the 1990s to 2000s was consistent with a weather-driven decline predicted by our models, which also explained up to 19% of the decadal variation in abundance between species. Species overwintering as larvae and multivoltine species were most sensitive to the effects of weather, whilst southerly-distributed species, species associated with woodland and unimproved grassland habitats, and pest species, showed the most positive long-term responses to climate change. Combined, these results show how climate change is already having significant impacts on the abundance of particular butterfly and moth species, with likely future consequences for ecosystem function and services

Anthropogenic climate and land-use change drive short- and long-term biodiversity shifts across taxa

Climate change and habitat loss present serious threats to nature. Yet, due to a lack of historical land-use data, the potential for land-use change and baseline land-use conditions to interact with a changing climate to affect biodiversity remains largely unknown. Here, we use historical land use, climate data and species observation data to investigate the patterns and causes of biodiversity change in Great Britain. We show that anthropogenic climate change and land conversion have broadly led to increased richness, biotic homogenization and warmer-adapted communities of British birds, butterflies and plants over the long term (50+ years) and short term (20 years). Biodiversity change was found to be largely determined by baseline environmental conditions of land use and climate, especially over shorter timescales, suggesting that biodiversity change in recent periods could reflect an inertia derived from past environmental changes. Climate–land-use interactions were mostly related to long-term change in species richness and beta diversity across taxa. Semi-natural grasslands (in a broad sense, including meadows, pastures, lowland and upland heathlands and open wetlands) were associated with lower rates of biodiversity change, while their contribution to national-level biodiversity doubled over the long term. Our findings highlight the need to protect and restore natural and semi-natural habitats, alongside a fuller consideration of individual species’ requirements beyond simple measures of species richness in biodiversity management and policy

BICCO-Net II. Final report to the Biological Impacts of Climate Change Observation Network (BICCO-Net) Steering Group

• BICCO-Net Phase II presents the most comprehensive single assessment of climate change impacts on UK biodiversity to date. • The results provide a valuable resource for the CCRA 2018, future LWEC report cards, the National Adaptation Programme and other policy-relevant initiatives linked to climate change impacts on biodiversity

A preliminary modelling investigation into the safe correction zone for high tibial osteotomy

Purpose: High tibial osteotomy (HTO) re-aligns the weight-bearing axis (WBA) of the lower limb. The surgery reduces medial load (reducing pain and slowing progression of cartilage damage) while avoiding overloading the lateral compartment. The optimal correction has not been established. This study investigated how different WBA re-alignments affected load distribu- tion in the knee, to consider the optimal post-surgery re-alignment. Methods: We collected motion analysis and 7T MRI data from 3 healthy sub- jects, and combined this data to create sets of subject-specific finite element models (total=45 models). Each set of models simulated a range of potential post-HTO knee re-alignments. We shifted the WBA from its native align- ment to between 40% and 80% medial-lateral tibial width (corresponding to 2.8◦-3.1◦ varus and 8.5◦-9.3◦ valgus), in 3% increments. We then compared stress/pressure distributions in the models. Results/Discussion: Correcting the WBA to 50% tibial width (0◦ varus- valgus) approximately halved medial compartment stresses, with minimal changes to lateral stress levels, but provided little margin for error in under- correction. Correcting the WBA to a more commonly-used 62%-65% tibial width (3.4◦-4.6◦ valgus) further reduced medial stresses but introduced the danger of damaging lateral compartment tissues. To balance optimal loading environment with that of the historical risk of under-correction, we propose a new target: WBA correction to 55% tibial width (1.7◦-1.9◦ valgus), which anatomically represented the apex of the lateral tibial spine. Conclusions: Finite element models can successfully simulate a variety of HTO re-alignments. Correcting the WBA to 55% tibial width (1.7◦-1.9◦ valgus) optimally distributes medial and lateral stresses/pressures

A new approach to modelling the relationship between annual population abundance indices and weather data

Weather has often been associated with fluctuations in population sizes of species; however, it can be difficult to estimate the effects satisfactorily because population size is naturally measured by annual abundance indices whilst weather varies on much shorter timescales. We describe a novel method for estimating the effects of a temporal sequence of a weather variable (such as mean temperatures from successive months) on annual species abundance indices. The model we use has a separate regression coefficient for each covariate in the temporal sequence, and over-fitting is avoided by constraining the regression coefficients to lie on a curve defined by a small number of parameters. The constrained curve is the product of a periodic function, reflecting assumptions that associations with weather will vary smoothly throughout the year and tend to be repetitive across years, and an exponentially decaying term, reflecting an assumption that the weather from the most recent year will tend to have the greatest effect on the current population and that the effect of weather in previous years tends to diminish as the time lag increases. We have used this approach to model 501 species abundance indices from Great Britain and present detailed results for two contrasting species alongside an overall impression of the results across all species. We believe this approach provides an important advance to the challenge of robustly modelling relationships between weather and species population size

Pheromones and Other Semiochemicals for Monitoring Rare and Endangered Species

As global biodiversity declines, biodiversity and conservation have become ever more important research topics. Research in chemical ecology for conservation purposes has not adapted to address this need. During the last 10-15 years, only a few insect pheromones have been developed for biodiversity and conservation studies, including the identification and application of pheromones specifically for population monitoring. These investigations, supplemented with our knowledge from decades of studying pest insects, demonstrate that monitoring with pheromones and other semiochemicals can be applied widely for conservation of rare and threatened insects. Here, I summarize ongoing conservation research, and outline potential applications of chemical ecology and pheromone-based monitoring to studies of insect biodiversity and conservation research. Such applications include monitoring of insect population dynamics and distribution changes, including delineation of current ranges, the tracking of range expansions and contractions, and determination of their underlying causes. Sensitive and selective monitoring systems can further elucidate the importance of insect dispersal and landscape movements for conservation. Pheromone-based monitoring of indicator species will also be useful in identifying biodiversity hotspots, and in characterizing general changes in biodiversity in response to landscape, climatic, or other environmental changes