Development and validation of Fluid Structure Interaction Methods for an Oscillating Wave Surge Converter

The term fatigue loads on the Oyster Oscillating Wave Surge Converter (OWSC) is used to describe hydrostatic loads due to water surface elevation with quasi-static changes of state. Therefore a procedure to implement hydrostatic pressure distributions into finite element analysis of the structure is desired. Currently available experimental methods enable one to measure time variant water surface elevation at discrete locations either on or around the body of the scale model during tank tests. This paper discusses the development of a finite element analysis procedure to implement time variant, spatially distributed hydrostatic pressure derived from discretely measured water surface elevation. The developed method can process differently resolved (temporal and spatial) input data and approximate the elevation over the flap faces with user defined properties. The structural loads, namely the forces and moments on the body can then be investigated by post processing the numerical results. This method offers the possibility to process surface elevation or hydrostatic pressure data from computational fluid dynamics simulations and can thus be seen as a first step to a fluid-structure interaction model.

Determination of Non-linear Damping Coefficients of bottom-hinged Oscillating Wave Surge Converters Using Numerical Free Decay Tests

Linear wave theory models are commonly applied to predict the performance of bottom-hinged oscillating wave surge converters (OWSC) in operational sea states. To account for non-linear effects, the additional input of coefficients not included in the model itself becomes necessary. In ocean engineering it is
common practice to obtain damping coefficients of floating structures from free decay tests. This paper presents results obtained from experimental tank tests and numerical computational fluid dynamics simulations of OWSC’s. Agreement between numerical and experimental methods is found to be very good, with CFD providing more data points at small amplitude rotations.
Analysis of the obtained data reveals that linear quadratic-damping, as commonly used in time domain models, is not able to accurately model the occurring damping over the whole regime of rotation amplitudes. The authors
conclude that a hyperbolic function is most suitable to express the instantaneous damping ratio over the rotation amplitude and would be the best choice to be used in coefficient based time domain models.

Sovereignty, Article 4(2) TEU and the Respect of National Identities: Swinging the Balance of Power in Favour of the Member States?

The question of whether and to what extent sovereignty has been transferred to the European Union (EU) from its Member States remains a central debate within the EU and is interlinked with issues such as Kompetenz-Kompetenz, direct effect and primacy. Central to any claim to sovereignty is the principle of primacy, which requires that Member States uphold EU law over national law where there is a conflict. However, limitations to primacy can traditionally be found in national jurisprudence and the Maastricht Treaty introduced a possible EU limitation with the requirement that the EU respect national identities of Member States. The Lisbon Treaty provided only minimal further support to the principle of primacy whilst simultaneously developing the provision on national identities, now found within Article 4(2) TEU. There are indications from the literature, national constitutional courts and the Court of Justice of the EU that the provision is gathering strength as a legal tool and is likely to have a wider scope than the text might indicate. In its new role, Article 4(2) TEU bolsters the Member States’ claim to sovereignty and the possibility to uphold aspects crucial to them in conflict with EU law and the principle of primacy. Consequently, it is central to the relationship between the constitutional courts of the Member States and the CJEU, and where the final elements of control remain in ‘hard cases’. However, it does so as part of EU law, thereby facilitating the evasion of direct fundamental conflicts and reflecting the concept of constitutional pluralism.

Re-embedding economic and social constitutionalism: Normative Perspectives for the E

This chapter proposes a social re-embedding of European constitutionalism by offering a coherent interpretation of EU constitutional principles as contained in the initial articles of the Treaties and the EU’s economic and social constitution as developed by the Court of Justice. It starts from the assumption that European integration is not merely an inter-state endeavour, but also a process that affects social and economic actors, in other words societies all over Europe. It may well ultimately engender a European society – if we are prepared to conceive of a poly-centric society, consisting of diverse components from a wide range of regions, social actors and cultures. Proceeding from the assumption that constitutionalism can be a relevant notion for such a holistic approach to European integration, the chapter develops elements of European constitutionalism relating to socio-economic reality. As national constitutional law, European constitutional law is presented as necessarily incomplete. European constitutionalism will thus have to offer modes of adapting open norms to an ever changing and developing societal reality. The chapter outlines a framework for such constitutionalism which, at the same time, offers opportunities for reconciling the social and economic dimensions in the European integration project through a re-configured notion of constitutionalism.

Middleware mechanisms for agent mobility in wireless sensor and actuator networks

This paper describes middleware-level support for agent mobility, targeted at hierarchically structured wireless sensor and actuator network applications. Agent mobility enables a dynamic deployment and adaptation of the application on top of the wireless network at runtime, while allowing the middleware to optimize the placement of agents, e.g., to reduce wireless network traffic, transparently to the application programmer. The paper presents the design of the mechanisms and protocols employed to instantiate agents on nodes and to move agents between nodes. It also gives an evaluation of a middleware prototype running on Imote2 nodes that communicate over ZigBee. The results show that our implementation is reasonably efficient and fast enough to support the envisioned functionality on top of a commodity multi-hop wireless technology. Our work is to a large extent platform-neutral, thus it can inform the design of other systems that adopt a hierarchical structuring of mobile components. © 2012 ICST Institute for Computer Science, Social Informatics and Telecommunications Engineering.

Millimeter-wave Beam Scanning Antennas using Liquid Crystals

Two Liquid crystal-based reflectarrays that operate at 100 GHz and 125 GHz are presented. The first prototype (100 GHz) is used to validate the modeling and the design procedure proposed for this class of antenna. Experimental validation of the beam scanning is carried out by measuring the received power in a quasi-optical test bench, which is able to rotate the receiver in the horizontal plane. These results are used to design a second prototype antenna (125 GHz) which exhibits 2D beam scanning capabilities with a large bandwidth and scanning range that is sufficient for radar and communications applications.

165/183 GHz FSS for the MetOp Second Generation Microwave Sounder Instrument

This paper reports the design of a Frequency Selective Surface (FSS) which simultaneously allows transmission of 175.3 – 191.3 GHz radiation and rejection from 164 - 167 GHz with a loss <0.5 dB for TE wave polarization at 45° incidence. The state-of-the art filter consists of three air spaced perforated screens with unit cells that are composed of nested resonant slots. The FSS satisfies the stringent electromagnetic performance requirements for signal demultiplexing in the quasi-optical feed train of the Microwave Sounder (MWS) instrument which is under development for the MetOp-SG mission.

Gas generation in interconnected power systems with high wind power penetration

Increasing installed capacities of wind power in an effort to achieve sustainable power systems for future generations pose problems for system operators. Volatility in generation volumes due to the adoption of stochastic wind power is increasing. Storage has been shown to act as a buffer for these stochastic energy sources, facilitating the integration of renewable energy into a historically inflexible power system. This paper examines peak and off peak benefits realised by installing a short term discharge storage unit in a system with a high penetration of wind power in 2020. A fully representative unit commitment and economic dispatch model is used to analyse two scenarios, one ‘with storage’ and one ‘without storage’. Key findings of this preliminary study show that wind curtailment can be reduced in the storage scenario, with a larger reduction in peak time ramping of gas generators is realised.