XFEL resonant photo-pumping of dense plasmas and dynamic evolution of autoionizing core hole states

Similarly to the case of LIF (Laser-Induced Fluorescence), an equally revolutionary impact to science is expected from resonant X-ray photo-pumping. It will particularly contribute to a progress in high energy density science: pumped core hole states create X-ray transitions that can escape dense matter on a 10 fs-time scale without essential photoabsorption, thus providing a unique possibility to study matter under extreme conditions. In the first proof of principle experiment at the X-ray Free Electron Laser LCLS at SCLAC [Seely, J., Rosmej, F.B., Shepherd, R., Riley, D., Lee, R.W. Proposal to Perform the 1^st High Energy Density Plasma Spectroscopic Pump/Probe Experiment", approved LCLS proposal L332 (2010)] we have successfully pumped inner-shell X-ray transitions in dense plasmas. The plasma was generated with a YAG laser irradiating solid Al and Mg targets attached to a rotating cylinder. In parallel to the optical laser beam, the XFEL was focused into the plasma plume at different delay times and pump energies. Pumped X-ray transitions have been observed with a spherically bent crystal spectrometer coupled to a Princeton CCD. By using this experimental configuration, we have simultaneously achieved extremely high spectral (λ/δλ ≈ 5000) and spatial resolution (δx≈70 μm) while maintaining high luminosity and a large spectral range covered (6.90 - 8.35 Å). By precisely measuring the variations in spectra emitted from plasma under action of XFEL radiation, we have successfully demonstrated transient X- ray pumping in a dense plasma.

Optimal day-ahead scheduling of integrated urban energy systems

An optimal day-ahead scheduling method (ODSM) for the integrated urban energy system (IUES) is introduced, which considers the reconfigurable capability of an electric distribution network. The hourly topology of a distribution network, a natural gas network, the energy centers including the combined heat and power (CHP) units, different energy conversion devices and demand responsive loads (DRLs), are optimized to minimize the day-ahead operation cost of the IUES. The hourly reconfigurable capability of the electric distribution network utilizing remotely controlled switches (RCSs) is explored and discussed. The operational constraints from the unbalanced three-phase electric distribution network, the natural gas network, and the energy centers are considered. The interactions between the electric distribution network and the natural gas network take place through conversion of energy among different energy vectors in the energy centers. An energy conversion analysis model for the energy center was developed based on the energy hub model. A hybrid optimization method based on genetic algorithm (GA) and a nonlinear interior point method (IPM) is utilized to solve the ODSM model. Numerical studies demonstrate that the proposed ODSM is able to provide the IUES with an effective and economical day-ahead scheduling scheme and reduce the operational cost of the IUES.

Catalysing the Irish Energy Transition: Capacities and Challenges

The transition to a “low carbon, climate resilient and environmentally sustainable economy by the end of the 
year 2050” has been conceptualised as the “national transition objective” in the Irish Climate Action and Low Carbon Development Bill, passed in late 2015. This has raised a myriad of questions over how this can be operationalised and resourced and whether it can maintain political momentum. This paper assesses the utility of framings informed by the transitions (MLP) and technological innovation systems perspectives in contributing to transformative societal processes, by examining their application in an Irish case study on policy and technology. Through a qualitative exploration of the broader societal and policy context of the energy sector and a more detailed examination of the innovation systems of selected niche technologies (bioenergy and electric vehicles), the Irish case study sought to identify potential catalysts for a sustainability transition in the energy sector in Ireland: where these exist, how these are being built or enabled, and barriers to change. Following a discussion on the theoretical approaches used, a description will be given of how these were applied in the conducting of the research on transition in Ireland case study and the key findings which emerged. A critical reflection will then be made on the utility of these perspectives (as applied) to contribute to broader processes of societal transformation in Ireland.

Benchmarking Energy Transitions: An Irish Case Study

The challenges of a low carbon energy transition have now been recognized by most nation states, each of whom have responded with differing visions, strategies and programmes, with variable veracity and effectiveness. Given the complexity of each country’s energy system (and sub-systems such as mobility, food etc), the differing sources and wealth of indigenous energy resources, the variable legacy of the fossil fuel regime and differing capacity to respond to global shifts in energy markets, it is clear that each country will respond to this challenge in very different ways.
This poses difficulties for understanding the extent to which a transition may be taking hold in any territory as simple indicators such as GHG emission data or increases in renewable energy ignore the complex contexts in which transitions take place. Drawing on the results of a study, funded by the Irish Environmental Protection Agency (Characterizing and Catalyzing Transitions) and using the wider theoretical framework of socio-technological transitions, this paper will explore the challenges, virtues and constraints of attempting to ‘benchmark’ the Republic of Ireland’s transition. This will lead to wider observations on the normative nature of benchmarking and a critical review of how we conceptualize the very idea of transition.

Do Changes in Current Flow as a Result of Arrays of Tidal Turbines Have an Effect on Benthic Communities?

Arrays of tidal energy converters have the potential to provide clean renewable energy for future generations. Benthic communities may, however, be affected by changes in current speeds resulting from arrays of tidal converters located in areas characterised by strong currents. Current speed, together with bottom type and depth, strongly influence benthic community distributions; however the interaction of these factors in controlling benthic dynamics in high energy environments is poorly understood. The Strangford Lough Narrows, the location of SeaGen, the world’s first single full-scale, grid-compliant tidal energy extractor, is characterised by spatially heterogenous high current flows. A hydrodynamic model was used to select a range of benthic community study sites that had median flow velocities between 1.5–2.4 m/s in a depth range of 25–30 m. 25 sites were sampled for macrobenthic community structure using drop down video survey to test the sensitivity of the distribution of benthic communities to changes in the flow field. A diverse range of species were recorded which were consistent with those for high current flow environments and corresponding to very tide-swept faunal communities in the EUNIS classification. However, over the velocity range investigated, no changes in benthic communities were observed. This suggested that the high physical disturbance associated with the high current flows in the Strangford Narrows reflected the opportunistic nature of the benthic species present with individuals being continuously and randomly affected by turbulent forces and physical damage. It is concluded that during operation, the removal of energy by marine tidal energy arrays in the far-field is unlikely to have a significant effect on benthic communities in high flow environments. The results are of major significance to developers and regulators in the tidal energy industry when considering the environmental impacts for site licences.

Resolving conflict in bipolar societies: The fate of political settlements in Fiji and Northern Ireland

Ethnically divided societies that might be described as ‘balanced bicommunal’ (where there are two communities, each of which comes close to representing half of the population) pose a particular challenge to conventional principles of collective decision-making, and commonly threaten political stability. This article analyses the experience of two such societies – Northern Ireland and Fiji – with a view to exploring whether there are common processes in the route by which political stability has been pursued. We assess the manner in which a distinctive relationship with Great Britain and its political culture has interacted with local conditions to produce a highly competitive, bipolar party system. This leads to consideration of the devices that have been adopted in an effort to bridge the gap between the communities: the Fiji constitution as amended in 1997, and Northern Ireland’s Good Friday Agreement of 1998. We focus, in particular, on the use of unusual (preferential voting) formulas for the election of parliamentarians and of an inclusive principle in the selection of ministers, and consider the contribution of these institutional devices to the attainment of political stability. We find that, in both cases, the intervention of forces from outside the political system had a decisive impact, though in very different ways. In addition to being underpinned by solid institutional design, for political settlements to work effectively, some minimal level of trust between rival elites is required.