A conceptual framework for transportation research at Mississippi Test Facility of NASA

Constructing models of transportation system in U

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Siglo XIX. Cart

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Siglo XIX. Cart

Assessing fish–fishery dynamics from a spatially explicit metapopulation perspective reveals winners and losers in fisheries management

Sustainable management of living resources must reconcile biodiversity conservation and socioeconomic viability of human activities. In the case of fisheries, sustainable management design is made challenging by the complex spatiotemporal interactions between fish and fisheries. We develop a comprehensive metapopulation framework integrating data on species life-history traits, connectivity and habitat distribution to identify priority areas for fishing regulation and assess how management impacts are spatially distributed. We trial this approach on European hake fisheries in the north-western Mediterranean, where we assess area-based management scenarios in terms of stock status and fishery productivity to prioritize areas for protection. Model simulations show that local fishery closures have the potential to enhance both spawning stock biomass and landings on a regional scale compared to a status quo scenario, but that improving protection is easier than increasing productivity. Moreover, the interaction between metapopulation dynamics and the redistribution of fishing effort following local closures implies that benefits and drawbacks are heterogeneously distributed in space, the former being concentrated in the proximity of the protected site. A network analysis shows that priority areas for protection are those with the highest connectivity (as expressed by network metrics) if the objective is to improve the spawning stock, while no significant relationship emerges between connectivity and potential for increased landings. Synthesis and applications. Our framework provides a tool for (1) assessing area-based management measures aimed at improving fisheries outcomes in terms of both conservation and socioeconomic viability and (2) describing the spatial distribution of costs and benefits, which can help guide effective management and gain stakeholder support. Adult dispersal remains the main source of uncertainty that needs to be investigated to effectively apply our model to fisheries regulation

Making protected areas effective for biodiversity, climate and food

The spatial extent of marine and terrestrial protected areas (PAs) was among the most intensely debated issues prior to the decision about the post-2020 Global Biodiversity Framework (GBF) of the Convention on Biological Diversity. Positive impacts of PAs on habitats, species diversity and abundance are well documented. Yet, biodiversity loss continues unabated despite efforts to protect 17% of land and 10% of the oceans by 2020. This casts doubt on whether extending PAs to 30%, the agreed target in the Kunming-Montreal GBF, will indeed achieve meaningful biodiversity benefits. Critically, the focus on area coverage obscures the importance of PA effectiveness and overlooks concerns about the impact of PAs on other sustainability objectives. We propose a simple means of assessing and visualising the complex relationships between PA area coverage and effectiveness and their effects on biodiversity conservation, nature-based climate mitigation and food production. Our analysis illustrates how achieving a 30% PA global target could be beneficial for biodiversity and climate. It also highlights important caveats: (i) achieving lofty area coverage objectives alone will be of little benefit without concomitant improvements in effectiveness, (ii) trade-offs with food production particularly for high levels of coverage and effectiveness are likely and (iii) important differences in terrestrial and marine systems need to be recognized when setting and implementing PA targets. The CBD's call for a significant increase in PA will need to be accompanied by clear PA effectiveness goals to reduce and revert dangerous anthropogenic impacts on socio-ecological systems and biodiversity

Quantification of uncertainty in machining operations for on-machine acceptance.

Manufactured parts are designed with acceptance tolerances, i.e. deviations from ideal design conditions, due to unavoidable errors in the manufacturing process. It is necessary to measure and evaluate the manufactured part, compared to the nominal design, to determine whether the part meets design specifications. The scope of this research project is dimensional acceptance of machined parts; specifically, parts machined using numerically controlled (NC, or also CNC for Computer Numerically Controlled) machines. In the design/build/accept cycle, the designer will specify both a nominal value, and an acceptable tolerance. As part of the typical design/build/accept business practice, it is required to verify that the part did meet acceptable values prior to acceptance. Manufacturing cost must include not only raw materials and added labor, but also the cost of ensuring conformance to specifications. Ensuring conformance is a substantial portion of the cost of manufacturing. In this project, the costs of measurements were approximately 50% of the cost of the machined part. In production, cost of measurement would be smaller, but still a substantial proportion of manufacturing cost. The results of this research project will point to a science-based approach to reducing the cost of ensuring conformance to specifications. The approach that we take is to determine, a priori, how well a CNC machine can manufacture a particular geometry from stock. Based on the knowledge of the manufacturing process, we are then able to decide features which need further measurements from features which can be accepted 'as is' from the CNC. By calibration of the machine tool, and establishing a machining accuracy ratio, we can validate the ability of CNC to fabricate to a particular level of tolerance. This will eliminate the costs of checking for conformance for relatively large tolerances

Commissioning the Cryogenic System of the First LHC Sector

The LHC machine, composed of eight sectors with superconducting magnets and accelerating cavities requires a complex cryogenic system providing high cooling capacities (18 kW equivalent at 4.5 K and 2.4  W at 1.8 K per sector produced in large cold boxes and distributed via 3.3-km cryogenic transfer lines). After individual reception tests of the cryogenic subsystems (cryogen storages, refrigerators, cryogenic transfer lines and distribution boxes) performed since 2000, the commissioning of the cryogenic system of the first LHC sector has been under way since November 2006. After a brief introduction to the LHC cryogenic system and its specificities, the commissioning is reported detailing the preparation phase (pressure and leak tests, circuit conditioning and flushing), the cool-down sequences including the handling of cryogenic fluids, the magnet powering phase and finally the warm-up. Preliminary conclusions on the commissioning of the first LHC sector will be drawn with the review of the critical points already solved or still pending. The last part of the paper reports on the first operational experience of the LHC cryogenic system in the perspective of the commissioning of the remaining LHC sectors and the beam injection test

Optimized fishing through periodically harvested closures

1. Periodically harvested closures (PHCs) are a traditional form of fisheries management that improve fishing efficiency during harvests, partly by reducing fish wariness to fishers during closed periods. However, whether PHCs also result in high yields and healthy marine ecosystems is unknown, even as PHCs are being promoted as a culturally appropriate management tool in the Indo-Pacific.2. We integrated field-derived estimates of change in fish wariness into a bioeconomic fisheries model to quantify to what degree PHCs can maximize harvest efficiency, fisheries yield and fish stock biomass.3. Our model indicated that PHCs that had a closure period of one to a few years between a single pulse harvest were able to generate equivalent fisheries yield and stock biomass levels, with greater harvest efficiency than was able to be achieved using permanent closures and other fisheries management tools.4. Fish life-history traits had little impact on the optimality of PHCs in maximizing the triple objective of harvest efficiency, fisheries yield and stock abundance, with overfishing similarly having little effect at anything under extreme levels. Under moderate overfishing, there was a trade-off between PHCs, which maximised harvest efficiency, and no-take permanent closures that maximised yield. However, the former outweighed the latter, and only at extreme levels of overfishing, where stock was reduced to < 18 % of unfished biomass, were permanent closures favoured over PHCs

Making protected areas effective for biodiversity, climate and food

The spatial extent of marine and terrestrial protected areas (PAs) was amongst the most intensely debated issues prior to the decision about the post-2020 Global Biodiversity Framework (GBF) of the Convention on Biological Diversity. Positive impacts of PAs on habitats, species diversity and abundance are well documented. Yet, biodiversity loss continues unabated despite efforts to protect 17% of land and 10% of the oceans by 2020. This casts doubt on whether extending PAs to 30%, the agreed target in the Kunming-Montreal GBF, will indeed achieve meaningful biodiversity benefits. Critically, the focus on area coverage obscures the importance of PA effectiveness and overlooks concerns about the impact of PAs on other sustainability objectives. We propose a simple means of assessing and visualising the complex relationships between PA area coverage and effectiveness and their effects on biodiversity conservation, nature-based climate mitigation and food production. Our analysis illustrates how achieving a 30% PA global target could be beneficial for biodiversity and climate. It also highlights important caveats: i) achieving lofty area coverage objectives alone will be of little benefit without concomitant improvements in effectiveness, ii) trade-offs with food production particularly for high levels of coverage and effectiveness are likely and iii) important differences in terrestrial and marine systems need to be recognized when setting and implementing PA targets. The CBD's call for a significant increase in protected area will need to be accompanied by clear PA effectiveness goals to reduce and revert dangerous anthropogenic impacts on socio-ecological systems and biodiversity

Escaping the perfect storm of simultaneous climate change impacts on agriculture and marine fisheries

The availability and production of food is threatened by climate change, with subsequent implications for food security and the global economy. In this study we assessed how the impacts of climate change on agriculture and marine fisheries interact under a range of scenarios. The 'business-as-usual' scenario would lead to ~90% of the global population, particularly in least developed countries, being exposed to declines in the productivity of both sectors, and < 3% of the world would experience productivity gains in both sectors. With strong mitigation equivalent to meeting Paris Agreement commitments, most countries including both the most vulnerable and the largest carbon emitters would show net gains in both agricultural and fisheries sectors