337 research outputs found

    The Joint Archives Quarterly, Volume 06.02: Summer 1995

    Get PDF

    Final results from the EU project AVATAR: aerodynamic modelling of 10 MW wind turbines

    Get PDF
    This paper presents final results from the EU project AVATAR in which aerodynamic models are improved and validated for wind turbines on a scale of 10 MW and more. Special attention is paid to the improvement of low fidelity engineering (BEM based) models with higher fidelity (CFD) models but also with intermediate fidelity free vortex wake (FVW) models. The latter methods were found to be a good basis for improvement of induction modelling in engineering methods amongst others for the prediction of yawed cases, which in AVATAR was found to be one of the most challenging subjects to model. FVW methods also helped to improve the prediction of tip losses. Aero-elastic calculations with BEM based and FVW based models showed that fatigue loads for normal production cases were over predicted with approximately 15% or even more. It should then be realised that the outcome of BEM based models does not only depend on the choice of engineering add-ons (as is often assumed) but it is also heavily dependent on the way the induced velocities are solved. To this end an annulus and element approach are discussed which are assessed with the aid of FVW methods. For the prediction of fatigue loads the so-called element approach is recommended but the derived yaw models rely on an annulus approach which pleads for a generalised solution method for the induced velocities

    Latest results from the EU project AVATAR: aerodynamic modelling of 10 MW wind turbines

    Get PDF
    This paper presents the most recent results from the EU project AVATAR in which aerodynamic models are improved and validated for wind turbines on a scale of 10 MW and more. Measurements on a DU 00-W-212 airfoil are presented which have been taken in the pressurized DNW-HDG wind tunnel up to a Reynolds number of 15 Million. These measurements are compared with measurements in the LM wind tunnel for Reynolds numbers of 3 and 6 Million and with calculational results. In the analysis of results special attention is paid to high Reynolds numbers effects. CFD calculations on airfoil performance showed an unexpected large scatter which eventually was reduced by paying even more attention to grid independency and domain size in relation to grid topology. Moreover calculations are presented on flow devices (leading and trailing edge flaps and vortex generators). Finally results are shown between results from 3D rotor models where a comparison is made between results from vortex wake methods and BEM methods at yawed conditions

    Renal Compression in Heart Failure The Renal Tamponade Hypothesis

    Get PDF
    Renal dysfunction is one of the strongest predictors of outcome in heart failure. Several studies have revealed that both reduced perfusion and increased congestion (and central venous pressure) contribute to worsening renal function in heart failure. This paper proposes a novel factor in the link between cardiac and renal dysfunction: "renal tamponade" or compression of renal structures caused by the limited space for expansion. This space can be limited either by the rigid renal capsule that encloses the renal interstitial tissue or by the layer of fat around the kidneys or by the peritoneal space exerting pressure on the retroperitoneal kidneys. Renal decapsulation in animal models of heart failure and acute renal ischemia has been shown effective in alleviating pressure-related injury within the kidney itself, thus supporting this concept and making it a potentially interesting novel treatment in heart failure. (J Am Coll Cardiol HF 2022;10:175-183) (c) 2022 The Authors. Published by Elsevier on behalf of the American College of Cardiology Foundation. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/)

    De financiële verhouding onder de loep

    Get PDF

    Unknown makes unloved:A case study on improving integrated health and social care in the Netherlands using a participatory approach

    Get PDF
    Many initiatives integrating health and social care have been implemented in order to provide adequate care and support to older people living at home. Further development of existing initiatives requires iterative processes of developing, implementing and evaluating improvements to current practice. This case study provides insight into the process of improving an existing integrated care initiative in the Netherlands. Using a participatory approach, researchers and local stakeholders collaborated to develop and implement activities to further improve collaboration between health and social care professionals. Improvement activities included interprofessional meetings focussing on reflection and mutual learning and workplace visits. Researchers evaluated the improvement process, using data triangulation of multiple qualitative and quantitative data sources. According to participating professionals, the improvement activities improved their communication and collaboration by establishing mutual understanding and trust. Enabling factors included the safe and informal setting in which the meetings took place and the personal relationships they developed during the project. Different organisational cultures and interests and a lack of ownership and accountability among managers hindered the improvement process, whereas issues such as staff shortages, time constraints and privacy regulations made it difficult to implement improvements on a larger scale. Still, the participatory approach encouraged the development of partnerships and shared goals on the level of both managers and professionals. This case study highlights that improving communication between professionals is an important first step in improving integrated care. In addition, it shows that a participatory approach, in which improvements are co-created and tailored to local priorities and needs, can help in the development of shared goals and trust between stakeholders with different perspectives. However, stakeholders' willingness and ability to participate in such an improvement process is challenged by many factors
    • …
    corecore