Measurement of air distribution and void fraction of an upwards air-water flow using electrical resistance tomography and a wire-mesh sensor

Measurements on an upwards air-water flow are reported that were obtained simultaneously with a dual-plane electrical resistance tomograph (ERT) and a wire-mesh sensor (WMS). The ultimate measurement target of both ERT and WMS is the same, the electrical conductivity of the medium. The ERT is a non-intrusive device whereas the WMS requires a net of wires that physically crosses the flow. This paper presents comparisons between the results obtained simultaneously from the ERT and the WMS for evaluation and calibration of the ERT. The length of the vertical testing pipeline section is 3 m with an internal diameter of 50 mm. Two distinct sets of air-water flow rate scenarios, bubble and slug regimes, were produced in the experiments. The fast impedance camera ERT recorded the data at an approximate time resolution of 896 frames per second (fps) per plane in contrast with the 1024 fps of the wire-mesh sensor WMS200. The set-up of the experiment was based on well established knowledge of air-water upwards flow, particularly the specific flow regimes and wall peak effects. The local air void fraction profiles and the overall air void fraction were produced from two systems to establish consistency for comparison of the data accuracy. Conventional bulk flow measurements in air mass and electromagnetic flow metering, as well as pressure and temperature, were employed, which brought the necessary calibration to the flow measurements. The results show that the profiles generated from the two systems have a certain level of inconsistency, particularly in a wall peak and a core peak from the ERT and WMS respectively, whereas the two tomography instruments achieve good agreement on the overall air void fraction for bubble flow. For slug flow, when the void fraction is over 30%, the ERT underestimates the void fraction, but a linear relation between ERT and WMS is still observed

Political Entrepreneurship in the Field of Māori Sovereignty in Aotearoa New Zealand

Individual actors have the potential to shape political outcomes through creative use of opportunities. Political entrepreneurship identifies how such actors recognise and exploit opportunities, for personal or collective gain. The existing literature focuses on individuals operating within institutional settings, with less attention paid to other types of actors. In this article, I argue for an expansion of the political entrepreneurship framework, by considering individuals in the electoral and protest arenas. An examination of the field of Māori sovereignty, or tino rangatiratanga, in Aotearoa New Zealand allows exploration of prominent actors’ innovative strategies and practices. The findings highlight the actors’ reliance on identity in mobilising support within the community, to press claims. Broadening the application of political entrepreneurship demonstrates the roles of social, cultural and political capital in influencing outcomes, by identifying opportunities available to individuals embedded in the community and according to the context of the arena

Working across boundaries: Science-policy interfaces and international forest politics

If scientific knowledge is to influence international environmental policy it needs to be recognised as authoritative and impartial by key politicians and policy makers. In the case of climate change this is achieved by a boundary organisation, the Intergovernmental Panel on Climate Change (IPCC), which enables climate scientists to demonstrate the veracity of their research to climate policy makers while, for the most part, maintaining scientific integrity and resisting political interference in scientific conclusions. However, in the absence of such an organisation for forest science the international forest science community has come forward and created its own mechanism - the Global Forest Expert Panels - which responds to demands from the forest policy community for knowledge in particular areas and which in some respects is based on the IPCC model. However, even if a more effective forest-science policy boundary organisation were to exist, progress in international forest policy would be constrained by some long standing political divisions, in particular on the financing of sustainable forest management

User requirements for the snow and land ice services - CryoLand

CryoLand (2011-2015) is a project carried out within the 7th Framework of the European Commission aimed at developing downstream services for monitoring seasonal snow, glaciers and lake/river ice primarily based on satellite remote sensing. The services target private and public users from a wide variety of application areas, and aim to develop sustainable services after the project is completed. The project has performed a thorough user requirement survey in order to derive targeted requirements for the service and provide recommendations for the design and priorities of the service. In this paper we describe the methods used, the major findings in this user survey, and how we used the results to design and specify the CryoLand snow and land ice service. The user requirement analysis shows that a European operational snow and land ice service is required and that there exists developed cryosphere products that can meet the specific needs. The majority of the users were mainly interested not only in the snow services, but also the lake/river ice products and the glacier products were desired