Electromagnetic and mechanical characterisation of ITER CS-MC conductors affected by transverse cyclic loading, part 1: coupling current loss

The magnetic field generated by a coil acts on the cable which results in a transverse force on the strands. This affects the interstrand contact resistances (Rc), the coupling current loss and current redistribution during field changes. A special cryogenic press has been built to study the mechanical and electrical properties of full-size ITER conductor samples under transverse, mechanical loading. The cryogenic press can transmit a variable (cyclic) force up to 650 kN/m to a conductor section of 400 mm length at 4.2 K. The jacket is partly opened in order to transmit the force directly onto the cable. In addition a superconducting dipole coil provides the magnetic field required to perform magnetisation measurements using pick-up coils. The various Rc's between strands selected from different positions inside the cable have been studied. The coupling loss time constants (nτ) during and after loading are verified for the Nb3Sn, 45 kA, 10 and 13 T, ITER Model Coil conductors. A summary of the results obtained with up to several tens of full loading cycles is presented. A significant decrease of the cable nτ after several cycles is observed. The values of the nτ's are discussed with respect to the Rc measurements and a multiple time constant model (MTC)

Electromagnetic and mechanical characteristaion of ITER CS-MC conductors affected by transverse cyclic loading, part 3: mechanical properties

The magnetic field and current of a coil wound with a cable-in-conduit conductor causes a transverse force pushing the cable to one side of the conduit. This load causes elastic and plastic deformation with friction as well as heating due to friction. A special cryogenic press has been built to study the mechanical and electrical properties of full-size ITER conductors under transverse mechanical loading. The cryogenic press can transmit at 4.2 K cyclic forces of 650 kN/m to conductor sections of 400 mm length representative of the peak load on a 50 kA conductor at 13 T. In order to transmit the force directly onto the cable, the conduit is opened partly to allow the cable deformation. The force acting on the cable as well as the displacement are monitored simultaneously in order to determine the mechanical heat generation due to friction. The mechanical loss under load is investigated for the Nb3Sn, 45 kA, 10 and 13 T, central solenoid model cell conductors (CSMC). The mechanical heat generation is determined from the hysteresis in the measured curves of displacement versus applied force. The first results of the effect of some 40 loading cycles are presented and the two conductors are compared. A significant decrease of the cable mechanical heat generation after loading cycles is observed

Evolution of Tidal Marsh Distribution under Accelerating Sea Level Rise

Tidal marshes are important ecological systems that are responding to sea level rise-driven changes in tidal regimes. Human development along the coastline creates barriers to marsh migration, moderating tidal marsh distributions. This study shows that in the Chesapeake Bay, USA an estuarine system with geographic and development variability, overall estuarine tidal marshes are projected to decline by approximately half over the next century. Tidal freshwater and oligohaline habitats, which are found in the upper reaches of the estuary and are typically backed by high elevation shorelines are particularly vulnerable. Due to their geological setting, losses of large extents of tidal freshwater habitat seem inevitable under sea level rise. However, in the meso/poly/euhaline zones that (in passive margin estuaries) are typically low relief areas, tidal marshes are capable of undergoing expansion. These areas should be prime management targets to maximize future tidal marsh extent. Redirecting new development to areas above 3 m in elevation and actively removing impervious surfaces as they become tidally inundated results in the maximum sustainability of natural coastal habitats. Under increasing sea levels and flooding, the future of tidal marshes will rely heavily on the policy decisions made, and the balance of human and natural landscapes in the consideration of future development

Impact Assessment and Management Challenges of Key Rural Human Health Infrastructure Under Sea Level Rise

Accelerating sea level rise in Virginia, United States, will significantly increase the flooding threat to low-lying roads, residences, and critical infrastructure as well as raise the water table, allowing saltwater intrusion into well water and threatening the function of septic fields. Although most of the adaptation work in Virginia has focused on urban economic centers, the majority of the coastline is rural and faces different threats and opportunities to address them compared to urban areas due to their reduced economic assets and their reliance on private infrastructure. In this case study, we assess the potential for geospatially quantifying impact to septic systems and adjacent water ways due to sea level rise. The case study found that the data necessary to reliably quantify these impacts on a state-wide scale are lacking and collection of that information needs to be prioritized given the potential for extensive sea level impacts

Synthesis of Shoreline, Sea Level Rise, and Marsh Migration Data for Wetland Restoration Targeting Final Report

Coastal marsh loss is a significant issue globally, due in part to rising sea levels and high levels of coastal human activity. Marshes have natural mechanisms to allow them to adapt to rising sea levels, however, migration across the landscape is one of those mechanisms and is frequently in conflict with human use of the shoreline. Ensuring the persistence of marshes into the future requires an understanding of where marshes are likely to migrate under sea level rise and targeting those areas for conservation and preservation activities. The goal of this project was to 1) compile existing datasets and information related to marsh migration under sea level rise-driven inundation due to forecasted climate change, topography of bay shorelines, shoreline condition (e.g., erosion rates, hardening, existing natural resources), existing wetland area and potential migration corridors, and other relevant data from around the Chesapeake Bay and 2) develop a methodology that synthesizes the information in a format that can be used to assist with marsh conservation and restoration decisions under multiple sea level rise scenarios (see associated report). This dataset is the resulting data from the methodology development

Early vocabulary development in deaf native signers: a British Sign Language adaptation of the communicative development inventories

Background: There is a dearth of assessments of sign language development in young deaf children. This study gathered age-related scores from a sample of deaf native signing children using an adapted version of the MacArthur-Bates CDI (Fenson et al., 1994). Method: Parental reports on children’s receptive and expressive signing were collected longitudinally on 29 deaf native British Sign Language (BSL) users, aged 8–36 months, yielding 146 datasets. Results: A smooth upward growth curve was obtained for early vocabulary development and percentile scores were derived. In the main, receptive scores were in advance of expressive scores. No gender bias was observed. Correlational analysis identified factors associated with vocabulary development, including parental education and mothers’ training in BSL. Individual children’s profiles showed a range of development and some evidence of a growth spurt. Clinical and research issues relating to the measure are discussed. Conclusions: The study has developed a valid, reliable measure of vocabulary development in BSL. Further research is needed to investigate the relationship between vocabulary acquisition in native and non-native signers