Modelling the impact of trapped lee waves on offshore wind farm power output

Mesoscale meteorological phenomena, including Atmospheric Gravity Waves, or Trapped Lee Waves (TLWs) can result from flow over topography or coastal transition in the presence of stable atmospheric stratification, particularly with strong capping inversions. Satellite images show that topographically forced TLWs frequently occur around near-coastal offshore wind farms. Yet current understanding of how they interact with individual turbines and whole farm energy output is limited. This parametric study investigates the potential impact of TLWs on a UK near-coastal offshore wind farm, Westermost Rough (WMR) resulting from westerly &ndash; south-westerly flow over topography in the Southeast of England. Computational fluid dynamics (CFD) modelling (using ANSYS-CFX) of TLW situations based on real atmospheric conditions at WMR was used to better understand turbine level and whole wind farm performance in this parametric study based on real inflow conditions. These simulations indicated that TLWs have the potential to significantly alter the windspeeds experienced by and the resultant power output of individual turbines and the whole wind farm. The location of the wind farm in the TLW wave cycle was an important factor in determining the magnitude of TLW impacts, given the expected wavelength of the TLW. Where the TLW trough was coincident with the wind farm, the turbine windspeeds and power outputs were more substantially reduced compared with when the TLW peak was coincident with the location of the wind farm. These reductions were mediated by turbine windspeeds and wake losses being superimposed on the TLW. However, the same initial flow conditions interacting with topography under different atmospheric stability settings produce differing near wind farm flow. Factors influencing the flow within the wind farm under the different stability conditions include differing: hill and coastal transition recovery, windfarm blockage effects and wake recovery. Determining how much of the differences in windspeed and power output in the wind farm resulted from the TLW is an area for future development.</p

Standardless, automated determination of Chlorine-35 by 35Cl nuclear magnetic resonance

A robust, fully automated, walk-up method is reported to quantify chloride in samples using 35Cl nuclear magnetic resonance. Minimal user input is required, no standards are acquired at the time of analysis; and the submission, acquisition, processing, and production of results are seamlessly integrated within existing software. The method demonstrated good linearity with R2 = 0.999 over three orders of magnitude of analyte concentration. The results were highly independent of analyte functionality, and the stability of instrument response was sufficient that analyses of additional standards were not required for a period of several months. At a nominal sample concentration of 10 mg/ml in D2O at 400 MHz, detection and quantitation limits of 0.1 and 0.5% (w/w) were achieved in a 1-h analysis time. Robust methodology was achieved by applying a rigorous approach to method development and validation to determine and evaluate fully the time- and sample-dependent factors that affect quantitation in these measurements

Evaluation of the wind shear at a site in the North-West of the Yucatan Peninsula, Mexico

Extrapolations from 10m above the ground up to the wind turbine hub height are frequently made to the data available for wind power assessments. Because of its simplicity, the power law profile has been one of the most popular mathematical formulations to predict the vertical wind shear. This paper presents an analysis of wind speed and wind shear in terms of the directional, diurnal and seasonal patterns for a site at the Autonomous University of Yucatan which experiences the tropical conditions of the Yucatan Peninsula in Mexico. This analysis takes a detailed look at frequency distributions to facilitate a comprehensive understanding of the local climatic conditions. Diurnal wind speed variations are shown to be affected in particular by the differing wind conditions associated with fetches over two distinct offshore regions. Seasonal behaviour suggests some departure from the oscillations expected from temperature variation. In addition, the use of rate of change of temperature at one height is proposed as an alternative to vertical temperature gradient inferred from two heights as an indicator of atmospheric stability which will affect the wind shear. The work presented is part of a regionally funded research program to evaluate the onshore and offshore wind potential in the north of the Yucatan Peninsula

Study of the offshore wind and its propagation inland of the northern zone of the Yucatan Peninsula, Eastern Mexico

A preliminary study of the wind characteristics of the northern zone of the Yucatan Peninsula, Eastern Mexico was undertaken for offshore and coastal sites using data measured from three measurement sites. Ten minutes averages of wind speeds, wind directions and ambient temperatures at two different heights were recorded from data measured over a year. The usual wind statistics analysis was undertaken to evaluate the atmospheric stability and the relation between the offshore and onshore winds. The results were compared with the models previously proposed by Monin-Obukhov and by Hsu

Initiating e-learning by stealth, participation and consultation in a late majority institution

The extent to which opportunities afforded by e-learning are embraced by an institution can depend in large measure on whether it is perceived as enabling and transformative or as a major and disruptive distraction. Most case studies focus on the former. This paper describes how e-learning was introduced into the latter environment. The sensitivity of competing pressures in a research intensive university substantially influenced the manner in which e-learning was promoted. This paper tells that story, from initial stealth to eventual university acknowledgement of the relevance of e-learning specifically to its own context

Statistical evaluation of SCADA data for wind turbine condition monitoring and farm assessment

Operational data from wind farms is crucial for wind turbine condition monitoring and performance assessment. In this paper, we analyse three wind farms with the aim to monitor environmental and operational conditions that might result in underperformance or failures. The assessment includes a simple wind speed characterisation and wake analysis. The evolution of statistical parameters is used to identify anomalous turbine behaviour. In total, 88 turbines and 12 failures are analysed, covering different component failures. Notwithstanding the short period of data available, several operational parameters are found to deviate from the farm trend in some turbines affected by failures. As a result, some parameters show better monitoring capabilities than others, for the detection of certain failures. However, the limitations of SCADA statistics are also shown as not all failures showed anomalies in the observed parameters

Optimised clinical study recruitment in palliative care: success strategies and lessons learned

© Author(s) (or their employer(s)) 2020. Recruitment challenges to clinical research studies in palliative care settings, particularly in hospices, are well documented. However, a recent study (Hospice Inpatient Deep vein thrombosis Detection (HIDDen) study) performed across five hospices in the UK recruited above target and on time. We describe strategies that aided successful recruitment in this study, and the lessons learnt for improving future studies. A recent review suggested that the ' Social Marketing Mix Framework' (SMMF) could help researchers with recruitment strategies in palliative care. We describe the recruiting strategies employed through the Social Marketing Mix lens and consider if it would be a useful framework for future researchers to use at the planning stage. Successful recruitment strategies employed in HIDDen study included: (i) addressing particular study-related factors, (ii) ensuring all patients were screened and offered participation if eligible, (iii) reducing impact on the clinical team through dedicated research nurses at sites, (iv) addressing research team issues with cross-cover between sites, where geographically possible, and (v) regular video conferencing meetings for support and collaborative solving of challenges. Limited pre-existing research infrastructure at most of the recruiting hospices created particular challenges. The SMMF provides a potential structure to help researchers to plan recruitment. However, to fully streamline trial set up and in order for hospice involvement in research to be realised systematically, a centralised approach to governance, organisational culture change whereby hospices embrace research as a legitimate purpose and consistent access to research staff are identified as key strategic elements promoting recruitment to studies in hospices

Direct procurement of donor heart with normothermic regional perfusion of abdominal organs.

PURPOSE: To evaluate if direct procurement of heart is possible in combination with normothermic regional perfusion of abdominal organs in donors after circulatory death. DESCRIPTION: A donation after circulatory death pathway was utilized for a 41-year-old female following an irreversible brain injury. After meeting criteria for the organ donation, heart was retrieved and re-animated on ex-situ perfusion system while abdominal organs were perfused using normothermic regional perfusion. EVALUATION: All the donated organs and their recipients had excellent short-term outcome. CONCLUSIONS: We demonstrated a successful combination of direct procurement of the heart and normothermic regional perfusion of the abdominal organs