Real-Gas Effects and Phase Separation in Underexpanded Jets at Engine-Relevant Conditions

A numerical framework implemented in the open-source tool OpenFOAM is presented in this work combining a hybrid, pressure-based solver with a vapor-liquid equilibrium model based on the cubic equation of state. This framework is used in the present work to investigate underexpanded jets at engine-relevant conditions where real-gas effects and mixture induced phase separation are probable to occur. A thorough validation and discussion of the applied vapor-liquid equilibrium model is conducted by means of general thermodynamic relations and measurement data available in the literature. Engine-relevant simulation cases for two different fuels were defined. Analyses of the flow field show that the used fuel has a first order effect on the occurrence of phase separation. In the case of phase separation two different effects could be revealed causing the single-phase instability, namely the strong expansion and the mixing of the fuel with the chamber gas. A comparison of single-phase and two-phase jets disclosed that the phase separation leads to a completely different penetration depth in contrast to single-phase injection and therefore commonly used analytical approaches fail to predict the penetration depth.Comment: Preprint submitted to AIAA Scitech 2018, Kissimmee, Florid

Development of criteria und procedures for the evaluation of the European Action Plan of Organic Food and Farming

Within the EU funded project ORGAP a toolbox for the evaluation of the European as well as national action plans for organic food and farming has been developed (www.orgap.org). This toolbox was based on a comparative analysis of national action plans in eight countries (CH, UK, DE, IT, DK, SI, CZ, NL, ES), a meta-evaluation of existing evaluations of national action plans, workshops with national stakeholders and a European Advisory Committee, interviews with experts. Furthermore synergies and conflicts between national and the European Action Plan were identified

Non-adiabatic Josephson Dynamics in Junctions with in-Gap Quasiparticles

Conventional models of Josephson junction dynamics rely on the absence of low energy quasiparticle states due to a large superconducting gap. With this assumption the quasiparticle degrees of freedom become "frozen out" and the phase difference becomes the only free variable, acting as a fictitious particle in a local in time Josephson potential related to the adiabatic and non-dissipative supercurrent across the junction. In this article we develop a general framework to incorporate the effects of low energy quasiparticles interacting non-adiabatically with the phase degree of freedom. Such quasiparticle states exist generically in constriction type junctions with high transparency channels or resonant states, as well as in junctions of unconventional superconductors. Furthermore, recent experiments have revealed the existence of spurious low energy in-gap states in tunnel junctions of conventional superconductors - a system for which the adiabatic assumption typically is assumed to hold. We show that the resonant interaction with such low energy states rather than the Josephson potential defines nonlinear Josephson dynamics at small amplitudes.Comment: 9 pages, 1 figur

Lessons learnt from ORGAP Project – planning, implementation and evaluation of Action Plans for Organic Food and Farming

Within the EU funded project ORGAP, a toolbox was developed for the evaluation of the European as well as national action plans for organic food and farming. Also recommendations and a resource manual for policy makers and stakeholders were developed. These were based on the analysis of national Organic Action Plans as well as stakeholder and expert consultation. The analysis showed that several EU member states have emphasised the need to balance supply-push policies with more market-focused demand-pull policies. An integrated approach is required and this has been to differing degrees through the formulation of multi-functional Organic Action Plans (OAPs), which also adress the dual roles of organic farming (from a policy perspective) to provide public goods and satisfy consumer demand. Eight Organic Action Plans, reviewed in the ORGAP project, vary with regard to the elaboration process, targets, objectives and the emphasis of measures on certain areas (e.g. market versus environment orientation). This variation is due to quite different political and socio-economic framework conditions for organic farming in these countries. It revealed that the weaknesses identified in the status quo analysis of the organic sector have only partly been translated to the targets and measures included in the action plan documents. Definition of the priorities for development of organic agriculture must be agreed by all relevant stakeholders. The priorities, and hence the programmes, will depend on correct analysis of the issues (and conflicts) that need to be addressed and clear objectives with measurable outcomes (for effective evaluation). For more information on the project, on the practical project manual and the evaluation toolbox for Organic Action Plans see project website www.orgap.or

The organic seed regulations framework in Europe – current status and recommendations for future development

Organic agriculture regulations, in particular European regulation EC 889/2008, prescribe the use of organically produced seed. For many cultivated plants, however, organic seed is often not available. This is mainly because investment in organic plant breeding and seed production has been low in the past. To bridge the gap between organic seed supply and demand, national and European regulations define certain circumstances under which organic producers are permitted to use non-organically produced seed. While the organic sector currently depends on these concessions, they also threaten to impede a further increase in the demand for organic seed, thereby potentially restraining present and future investment in organic seed production and plant breeding. We review the current status of the organic seed regulations framework by analysing key issues such as the role of the national derogation regimes, the role of expert groups, databases and seed prices. Key points are that (a) the situation of the organic seed sector has improved over the last few years; however, (b) reporting on organic seed to the EU by different countries needs to be harmonised; (c) the success of the organic seed sector depends critically on the implementation and improvement of national expert groups; and (d) to protect genetic diversity, the use of local varieties and landraces should not be impeded by organic seed regulations