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Evaluation of ballistic performance of STF impregnated fabrics under high velocity impact
No full textShear thickening fluid (STF) impregnated fabrics offer improved ballistic performance against impacts, but the effect becomes not obvious at high impact velocity (e.g. 300m/s) as reported by some. This paper presents findings from an investigation of STF-impregnated fabric panels against ballistic impact, and attempts to identify the failure mechanisms of such panels under high velocity impact, which will shed light on effects of STF-impregnated fabrics for low and high velocity impacts. Single-ply and 10-ply neat and STF-impregnated aramid fabric panels were experimented on at impact velocities around 500m/s. The results indicated that the specific energy absorption of the single-ply and 10-ply STF impregnated fabric panels was 44.8% and 64.1% lower than that of their neat counterparts respectively. The mechanisms were studied theoretically and morphologically. It was found that the projectile velocities perforating the fabrics were decreased by STF impregnation due to the total movement constraint of the primary yarns. This changes the failure mode from tensile dominant to shear dominant, increases the possibility of earlier damage and failure of the primary yarns, and reduces the pull out distance, causing decrease in the energy absorption. The findings are significant for guiding further design of STF impregnated fabric panels for ballistic protection
Ecologies of educational reflexivity and agency – a different way of thinking about equitable educational policies and practices for England and beyond?
No full textThe current UK education policy for Englandemphasis on equity and social mobility focuses on narrowing the educational attainment gap between more and less advantaged groups of young people – an approach that has strong parallels in many Anglophone countries around the world. We argue that these policy and associated practice proscriptions tend to privilege an individualised narrative of agency for young people, teachers and schools more generally. Our paper argues that this individualised approach is highly problematic in that it decontextualizes the complex and real agentic work of young people in schooling, making it difficult to empirically and theoretically account for differences in educational outcome between and within groups of young people. Informed by a social realist perspective, and in particular the work of Margaret Archer, we propose a theoretical model that we suggest provides greater explanatory and predictive power. The model focuses on the way ecologies of development emerge for young people. We suggest that such ecologies reflect different structural and cultural factors and processes, combining in ways that enable and/or constrain young people’s educational reflexivity and agency and their ensuing educational engagement and attainments. We believe that building a typology of such ecologies of educational reflexivity and agency provides improved ways of developing equitable educational policies and practice - ones that relate clearly to the compositional mix of young people in schools and enable the development of interventions that better relate to such ecologies
A novel technique to incorporate structural prior information into multi-modal tomographic reconstruction
No full textStoring renewables in the gas network: modelling of power-to-gas (P2G) seasonal storage flexibility in low carbon power systems
No full textThe power-to-gas (P2G) process, whereby excess renewable electrical energy is used to form hydrogen and/or synthetic natural gas that are injected, transported and stored in the gas network, has the prospect to become an important flexibility option for the seasonal storage of low-carbon electricity. This paper is the first to model and assess the potential of P2G when combined with gas seasonal storage operation accounting for the two networks’ characteristics and constraints (including the amount of hydrogen that can be blended with natural gas under different gas network conditions). Power system operation with P2G is analysed via a two-stage optimisation based on DC power flow in order to assess the gas production from otherwise curtailed renewables, also considering impact of P2G on short-term and long-term gas prices. Additionally, impact of P2G on gas network operation and its potentially required re-dispatch are evaluated with a steady-state gas flow model. Case studies conducted on the Great Britain gas and electrical transmission networks quantify benefits and limitations of the integrated usage of P2G with seasonal gas storage under different scenarios. The proposed model thus sets the fundamentals for further development of this emerging technology as a seasonal storage option in low-carbon power systems
Modelling, assessment and Sankey diagrams of integrated electricity-heat-gas networks in multi-vector district energy systems
No full textThe widespread use of decentralised multi-energy supply solutions such as gas-fired Combined Heat and Power (CHP), heat pumps, gas boilers, and so forth is more and more increasing the linkages between electricity, heat and gas distribution networks. However, there is currently no model able to model the three networks in an integrated manner and with a suitable level of detail for operational purposes. A multi-temporal simulation model, which has been implemented in a relevant MATLAB-Excel VBA tool, is presented in this paper to carry out integrated analysis of electricity, heat and gas distribution networks, with specific applications to multi-vector district energy systems. The network linkages have been modelled through a multi-vector efficiency matrix specifically developed to map the transformation of final demands into network energy flows while taking into account the inter-network locations of the individual supply technologies. The relevant coupled electrical, heat and gas flow equations have been solved simultaneously using a Newton-Raphson approach. A real case study of a district multi-energy system in the Campus of the University of Manchester illustrates the quantitative use of the model in different scenarios for technical, economic and environmental studies. Sankey diagrams of the energy flows across the networks are also presented to give a visual picture of the multi-energy interactions and losses in the district in different scenarios. The model can be flexibly adapted to generic network topologies and multi-energy supply technologies, and can thus be used for practical operational implementations as well as to inform planning of low carbon multi-vector energy systems
Reduction of elementary flux mode complexity enables rational metabolic engineering for biotechnological products
No full textOn the use of Dynamic Thermal Line Ratings for Improving Operational Tripping Schemes
No full textThe increasing volume of renewable and intermittent generation that is being connected to power systems means that system operators need more advanced dynamic control tools to manage the increase in congestion and the resulting pressure on system constraints. Dynamic thermal line rating (DTLR) is the thermal rating of a transmission line that is calculated in real-time based on online measurements of the loading of the asset and local weather conditions. This dynamic rating will usually be greater than the static rating that is currently used, as the static rating is defined for the worst case scenario. Therefore, using the dynamic rating allows the thermal constraint on a line to be relaxed and the maximum loading increased. An Operational Tripping Scheme (OTS) is a type of System Integrity Protection Scheme (SIPS) that is used to relieve overloads on transmission lines during stressed system conditions by tripping pre-selected generation assets that are connected to the protected lines. . An OTS is used to increase power flow on overhead lines, without building new assets or compromising security, but doing so results in potential generation constraints and higher system risk. This paper presents the novel integration of DTLRs into an existing OTS in order to improve its performance by reducing the likelihood of unnecessary generation tripping due to overly conservative line ratings. This novel OTS affords the system economic benefits, by avoiding unnecessary tripping, and improves system security, by limiting the propagation of disturbed conditions and avoiding unnecessary tripping actions that could initiate dangerous cascading events that might lead to system blackouts. The new scheme is an example of a Wide Area Monitoring, Protection and Control (WAMPAC) application
