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  • Report
    Few SPM, Schmidt O, Gambhir A, 2016,

    Electrical energy storage for mitigating climate change

    , Publisher: Grantham Institute, Imperial College London, 20
  • Journal article
    Kossieris P, Makropoulos C, Onof C, Koutsoyiannis Det al., 2016,

    A rainfall disaggregation scheme for sub-hourly time scales: coupling a Bartlett-Lewis based model with adjusting procedures

    , Journal of Hydrology, Vol: 556, Pages: 980-992, ISSN: 0022-1694

    Many hydrological applications, such as flood studies, require the use of long rainfall data at fine time scales varying from daily down to 1 min time step. However, in the real world there is limited availability of data at sub-hourly scales. To cope with this issue, stochastic disaggregation techniques are typically employed to produce possible, statistically consistent, rainfall events that aggregate up to the field data collected at coarser scales. A methodology for the stochastic disaggregation of rainfall at fine time scales was recently introduced, combining the Bartlett-Lewis process to generate rainfall events along with adjusting procedures to modify the lower-level variables (i.e., hourly) so as to be consistent with the higher-level one (i.e., daily). In the present paper, we extend the aforementioned scheme, initially designed and tested for the disaggregation of daily rainfall into hourly depths, for any sub-hourly time scale. In addition, we take advantage of the recent developments in Poisson-cluster processes incorporating in the methodology a Bartlett-Lewis model variant that introduces dependence between cell intensity and duration in order to capture the variability of rainfall at sub-hourly time scales. The disaggregation scheme is implemented in an R package, named HyetosMinute, to support disaggregation from daily down to 1-min time scale. The applicability of the methodology was assessed on a 5-min rainfall records collected in Bochum, Germany, comparing the performance of the above mentioned model variant against the original Bartlett-Lewis process (non-random with 5 parameters). The analysis shows that the disaggregation process reproduces adequately the most important statistical characteristics of rainfall at wide range of time scales, while the introduction of the model with dependent intensity-duration results in a better performance in terms of skewness, rainfall extremes and dry proportions.

  • Journal article
    Wearn OR, Carbone C, Rowcliffe JM, Bernard H, Ewers RMet al., 2016,

    Grain-dependent responses of mammalian diversity to land use and the implications for conservation set-aside

    , Ecological Applications, Vol: 26, Pages: 1409-1420, ISSN: 1939-5582

    Diversity responses to land-use change are poorly understood at local scales, hindering our ability to make forecasts and management recommendations at scales which are of practical relevance. A key barrier in this has been the underappreciation of grain-dependent diversity responses and the role that β-diversity (variation in community composition across space) plays in this. Decisions about the most effective spatial arrangement of conservation set-aside, for example high conservation value areas, have also neglected β-diversity, despite its role in determining the complementarity of sites. We examined local-scale mammalian species richness and β-diversity across old-growth forest, logged forest, and oil palm plantations in Borneo, using intensive camera- and live-trapping. For the first time, we were able to investigate diversity responses, as well as β-diversity, at multiple spatial grains, and across the whole terrestrial mammal community (large and small mammals); β-diversity was quantified by comparing observed β-diversity with that obtained under a null model, in order to control for sampling effects, and we refer to this as the β-diversity signal. Community responses to land use were grain dependent, with large mammals showing reduced richness in logged forest compared to old-growth forest at the grain of individual sampling points, but no change at the overall land-use level. Responses varied with species group, however, with small mammals increasing in richness at all grains in logged forest compared to old-growth forest. Both species groups were significantly depauperate in oil palm. Large mammal communities in old-growth forest became more heterogeneous at coarser spatial grains and small mammal communities became more homogeneous, while this pattern was reversed in logged forest. Both groups, however, showed a significant β-diversity signal at the finest grain in logged forest, likely due to logging-induced envir

  • Report
    van Sebille E, Spathi C, Gilbert A, 2016,

    The ocean plastic pollution challenge: towards solutions in the UK

    , Publisher: Grantham Institute, Imperial College London, 19
  • Journal article
    Kramer SC, Piggott MD, 2016,

    A correction to the enhanced bottom drag parameterisation of tidal turbines

    , Renewable Energy, Vol: 92, Pages: 385-396, ISSN: 0960-1481

    Hydrodynamic modelling is an important tool for the development of tidal stream energy projects. Many hydrodynamic models incorporate the effect of tidal turbines through an enhanced bottom drag. In this paper we show that although for coarse grid resolutions (kilometre scale) the resulting force exerted on the flow agrees well with the theoretical value, the force starts decreasing with decreasing grid sizes when these become smaller than the length scale of the wake recovery. This is because the assumption that the upstream velocity can be approximated by the local model velocity, is no longer valid. Using linear momentum actuator disc theory however, we derive a relationship between these two velocities and formulate a correction to the enhanced bottom drag formulation that consistently applies a force that remains close to the theoretical value, for all grid sizes down to the turbine scale. In addition, a better understanding of the relation between the model, upstream, and actual turbine velocity, as predicted by actuator disc theory, leads to an improved estimate of the usefully extractable energy. We show how the corrections can be applied (demonstrated here for the models MIKE 21 and Fluidity) by a simple modification of the drag coefficient.

  • Journal article
    Hunt I, Zhao Y, Patel Y, Offer GJet al., 2016,

    Surface cooling causes accelerated degradation compared to tab cooling for lithium-Ion pouch cells

    , Journal of the Electrochemical Society, Vol: 163, Pages: A1846-A1852, ISSN: 0013-4651

    One of the biggest causes of degradation in lithium-ion batteries is elevated temperature. In this study we explored the effects ofcell surface cooling and cell tab cooling, reproducing two typical cooling systems that are used in real-world battery packs. For newcells using slow-rate standardized testing, very little difference in capacity was seen. However, at higher rates, discharging the cellin just 10 minutes, surface cooling led to a loss of useable capacity of 9.2% compared to 1.2% for cell tab cooling. After cyclingthe cells for 1,000 times, surface cooling resulted in a rate of loss of useable capacity under load three times higher than cell tabcooling. We show that this is due to thermal gradients being perpendicular to the layers for surface cooling leading to higher localcurrents and faster degradation, but in-plane with the layers for tab cooling leading to more homogenous behavior. Understandinghow thermal management systems interact with the operation of batteries is therefore critical in extending their performance. Forautomotive applications where 80% capacity is considered end-of-life, using tab cooling rather than surface cooling would thereforebe equivalent to extending the lifetime of a pack by 3 times, or reducing the lifetime cost by 66%.

  • Journal article
    Brindley HE, Bantges RJ, 2016,

    The spectral signature of recent climate change

    , Current Climate Change Reports, Vol: 2, Pages: 112-126, ISSN: 2198-6061

    Spectrally resolved measurements of the Earth’s reflected shortwave (RSW) and outgoing longwave radiation (OLR) at the top of the atmosphere intrinsically contain the imprints of a multitude of climate relevant parameters. Here, we review the progress made in directly using such observations to diagnose and attribute change within the Earth system over the past four decades. We show how changes associated with perturbations such as increasing greenhouse gases are expected to be manifested across the spectrum and illustrate the enhanced discriminatory power that spectral resolution provides over broadband radiation measurements. Advances in formal detection and attribution techniques and in the design of climate model evaluation exercises employing spectrally resolved data are highlighted. We illustrate how spectral observations have been used to provide insight into key climate feedback processes and quantify multi-year variability but also indicate potential barriers to further progress. Suggestions for future research priorities in this area are provided.

  • Journal article
    Terrer C, Vicca S, Hungate BA, Phillips RP, Prentice ICet al., 2016,

    Mycorrhizal association as a primary control of the CO2 fertilization effect

    , Science, Vol: 353, Pages: 72-74, ISSN: 1095-9203

    Plants buffer increasing atmospheric CO2 concentrations through enhanced growth, but the question whether nitrogen availability constrains the magnitude of this ecosystem service remains unresolved. Synthesizing experiments from around the world, we show that CO2 fertilization is best explained by a simple interaction between nitrogen availability and mycorrhizal association. Plant species that associate with ectomycorrhizal fungi show a strong biomass increase (30 ± 3%, P<0.001) in response to elevated CO2 regardless of nitrogen availability, whereas low nitrogen availability limits CO2 fertilization (0 ± 5%, P=0.946) in plants that associate with arbuscular mycorrhizal fungi. The incorporation of mycorrhizae in global carbon cycle models is feasible, and crucial if we are to accurately project ecosystem responses and feedbacks to climate change.

  • Journal article
    Adams T, Mac Dowell N, 2016,

    Off-design point modelling of a 420 MW CCGT power plant integrated with an amine-based post-combustion CO2 capture and compression process

    , Applied Energy, Vol: 178, Pages: 681-702, ISSN: 1872-9118

    The use of natural gas for power generation is becoming increasingly important in many regions in the world. Given that the combined cycle gas turbine (CCGT) power stations are lower in capital cost and carbon intensity than their coal-fired counterparts, natural gas fired power stations are considered a vital part of the transition to a low carbon economy. However, CCGTs are not themselves “low carbon” and in order to reach a carbon intensity of less than 50 kgCO2/MWh, it will be necessary to decarbonise them via CCS, with post-combustion CCS currently regarded as being a promising technology for this application. In this study, we present a detailed model of a 420 MW triple-pressure reheat CCGT and evaluate its technical and economic performance under full and part load conditions. We evaluate the technical performance of our CCGT model by comparison to an equivalent model implemented in Thermoflow THERMOFLEX and observe agreement of power output and efficiency to within 4.1% and the temperature profile within the HRSG within 2.9%. We further integrate the CCGT with a dynamic model of an amine based CCS process, and observe a reduction in the base plant efficiency from 51.84% at full-load and 50.23% at 60% load by 8.64% points at full-load and 7.93% points at 60% load. A core conclusion of this paper is that CCGT power plants equipped with post-combustion CCS technologies are well suited to dynamic operation, as might be required in an energy system characterised by high penetrations of intermittent renewable power generation.

  • Journal article
    Carter E, Archer-Nicholls S, Ni K, Lai AM, Niu H, Secrest MH, Sauer SM, Schauer JJ, Ezzati M, Wiedinmyer C, Yang X, Baumgartner Jet al., 2016,

    Seasonal and Diurnal Air Pollution from Residential Cooking and Space Heating in the Eastern Tibetan Plateau.

    , Environmental Science & Technology, Vol: 50, Pages: 8353-8361, ISSN: 1520-5851

    Residential combustion of solid fuel is a major source of air pollution. In regions where space heating and cooking occur at the same time and using the same stoves and fuels, evaluating air-pollution patterns for household-energy-use scenarios with and without heating is essential to energy intervention design and estimation of its population health impacts as well as the development of residential emission inventories and air-quality models. We measured continuous and 48 h integrated indoor PM2.5 concentrations over 221 and 203 household-days and outdoor PM2.5 concentrations on a subset of those days (in summer and winter, respectively) in 204 households in the eastern Tibetan Plateau that burned biomass in traditional stoves and open fires. Using continuous indoor PM2.5 concentrations, we estimated mean daily hours of combustion activity, which increased from 5.4 h per day (95% CI: 5.0, 5.8) in summer to 8.9 h per day (95% CI: 8.1, 9.7) in winter, and effective air-exchange rates, which decreased from 18 ± 9 h(-1) in summer to 15 ± 7 h(-1) in winter. Indoor geometric-mean 48 h PM2.5 concentrations were over two times higher in winter (252 μg/m(3); 95% CI: 215, 295) than in summer (101 μg/m(3); 95%: 91, 112), whereas outdoor PM2.5 levels had little seasonal variability.

  • Journal article
    Zhao L, Moore J, O'Gorman EJ, Borett S, Tian W, Ma A, Zhang Het al., 2016,

    Weighting and indirect effects identify keystone species in food webs

    , Ecology Letters, Vol: 19, Pages: 1032-1040, ISSN: 1461-0248

    Species extinctions are accelerating globally, yet the mechanisms that maintain local biodiversity remain poorly understood. The extinction of species that feed on or are fed on by many others (i.e. ‘hubs’) has traditionally been thought to cause the greatest threat of further biodiversity loss. Very little attention has been paid to the strength of those feeding links (i.e. link weight) and the prevalence of indirect interactions. Here, we used a dynamical model based on empirical energy budget data to assess changes in ecosystem stability after simulating the loss of species according to various extinction scenarios. Link weight and/or indirect effects had stronger effects on food-web stability than the simple removal of ‘hubs’, demonstrating that both quantitative fluxes and species dissipating their effects across many links should be of great concern in biodiversity conservation, and the potential for ‘hubs’ to act as keystone species may have been exaggerated to date.

  • Journal article
    Costa DD, da Silva Pereira TA, Fragoso CR, Madani K, Uvo CBet al., 2016,

    Understanding drought dynamics during dry season in Eastern Northeast Brazil

    , Frontiers in Earth Science, Vol: 4, ISSN: 2296-6463

    Eastern Northeast Brazil (ENEB) generally experiences a high variability in precipitation in the dry season, with amplitudes that can overcome 500mm. The understanding of this variability can help in mitigating the socio-economic issues related to the planning and management of water resources this region, which is highly vulnerable to drought. This work aims to assess spatio-temporal variability of precipitation during the dry season and investigate the relationships between climate phenomena and drought events in the ENEB, using univariate (Spearman correlation) and multivariate statistical techniques, such as Principal Component Analysis, Cluster Analysis, and Maximum Covariance Analysis. The results indicate that the variability of precipitation in the dry season can be explained mainly (62%) by local physical conditions and climate conditions have a secondary contribution. Further analysis of the larger anomalous events suggests that the state of Atlantic and Pacific oceans can govern the occurrence of those events, and the conditions of Atlantic Ocean can be considered a potential modulator of anomalous phenomena of precipitation in ENEB.

  • Journal article
    Garcia Trenco A, White E, Shaffer M, Williams CKet al., 2016,

    A one-step Cu/ZnO Quasi-Homogeneous Catalyst for DME Production from Syn-gas

    , Catalysis Science & Technology, Vol: 6, Pages: 4389-4397, ISSN: 2044-4753

    A simple one-pot synthetic method allows the preparation of hybrid catalysts, based on colloidal Cu/ZnO nanoparticles(NPs), used for the liquid phase synthesis of DME from syngas. The method obviates the high temperature calcinations andpre-reduction treatments typically associated with such catalysts. The hybrid catalysts are applied under typicalindustrially relevant conditions. The nature of the hybrid catalysts, the influence of the acid component, mass ratiobetween components, and Cu/Zn composition are assessed. The best catalysts comprise a colloidal mixture of Cu/ZnONPs, as the methanol synthesis component, and -Al2O3, as the methanol dehydration component. These catalysts showhigh DME selectivity (65-70 %C). Interestingly, the activity (relative to Cu content) is up to three times higher than that forthe reference hybrid catalyst based on the commercial Cu/ZnO/Al2O3 methanol synthesis catalyst. The hybrid catalysts arestable for at least 20 h time-on-stream, not showing any significant sintering of the Cu0phase. Post-catalysis,TEM/EDXshows that the hybrid catalysts consist of Cu0and ZnO NPs with an average size of 5-7 nm with -Al2O3 particles in closeproximity.

  • Journal article
    Bantges RJ, Brindley HE, Chen XH, Huang XL, Harries JE, Murray JEet al., 2016,

    On the detection of robust multi-decadal changes in the Earth’s Outgoing Longwave Radiation spectrum

    , Journal of Climate, Vol: 29, Pages: 4939-4947, ISSN: 1520-0442

    Differences between Earth’s global mean all-sky outgoing longwave radiation spectrum as observed in 1970 [Interferometric Infrared Spectrometer (IRIS)], 1997 [Interferometric Monitor for Greenhouse Gases (IMG)], and 2012 [Infrared Atmospheric Sounding Instrument (IASI)] are presented. These differences are evaluated to determine whether these are robust signals of multidecadal radiative forcing and hence whether there is the potential for evaluating feedback-type responses. IASI–IRIS differences range from +2 K in the atmospheric window (800–1000 cm−1) to −5.5 K in the 1304 cm−1 CH4 band center. Corresponding IASI–IMG differences are much smaller, at 0.2 and −0.8 K, respectively. More noticeably, IASI–IRIS differences show a distinct step change across the 1042 cm−1 O3 band that is not seen in IASI–IMG comparisons. This step change is a consequence of a difference in behavior when moving from colder to warmer scenes in the IRIS data compared to IASI and IMG. Matched simulations for the relevant periods using ERA reanalyses mimic the spectral behavior shown by IASI and IMG rather than by IRIS. These findings suggest that uncertainties in the spectral response of IRIS preclude the use of these data for quantitative assessments of forcing and feedback processes.

  • Journal article
    Cooper MA, Michaelides K, Siegert MJ, Bamber JLet al., 2016,

    Paleofluvial landscape inheritance for Jakobshavn Isbræ catchment, Greenland

    , Geophysical Research Letters, Vol: 43, Pages: 6350-6357, ISSN: 1944-8007

    Subglacial topography exerts strong controls on glacier dynamics, influencing the orientation and velocity of ice flow, as well as modulating the distribution of basal waters and sediment. Bed geometry can also provide a long-term record of geomorphic processes, allowing insight into landscape evolution, the origin of which may predate ice sheet inception. Here we present evidence from ice-penetrating radar data for a large dendritic drainage network, radiating inland from Jakobshavn Isbræ, Greenland's largest outlet glacier. The size of the drainage basin is ∼450,000 km2 and accounts for about 20% of the total land area of Greenland. Topographic and basin morphometric analyses of an isostatically uplifted (ice-free) bedrock topography suggests that this catchment predates ice sheet initiation and has likely been instrumental in controlling the location and form of the Jakobshavn ice stream, and ice flow from the deep interior to the margin, now and over several glacial cycles.

  • Journal article
    Kirkman R, Voulvoulis N, 2016,

    The role of public communication in decision making for waste management infrastructure

    , Environmental Management, Vol: 203, Pages: 640-647, ISSN: 1432-1009

    Modern waste management provision seeks to meet challenging objectives and strategies while reflecting community aspirations and ensuring cost-effective compliance with statutory obligations. Its social acceptability, which affects both what systems (infrastructure) can be put in place and to what extent their implementation will be successful, is a multi-dimensional phenomenon, often not well understood. In light of the growing evidence that decisions to build new infrastructure are often contested by the public, there is a clear need to understand the role of scientific evidence in public perception, particularly as environmental infrastructure delivery is often objected to by the public on environmental grounds. In this paper the need for waste management infrastructure is reviewed, and the way its delivery in the UK has evolved is used as an example of the role of public perception in the planning and delivery of waste facilities. Findings demonstrate the vital role of public communication in waste management infrastructure delivery. Public perception must be taken into account early in the decision making process, with the public informed and engaged from the start. There is a pressing need for people not simply to accept but to understand and appreciate the need for infrastructure, the nature of infrastructure investments and development, the costs and the benefits involved, and the technological aspects. Scientific evidence and literacy have a critical role to play, facilitating public engagement in a process that empowers people, allowing them to define and handle challenges and influence decisions that will impact their lives. Problem ownership, and an increased probability of any solutions proposed being selected and implemented successfully are potential benefits of such approach.

  • Journal article
    Harrison SP, Bartlein PJ, Prentice IC, 2016,

    What have we learnt from palaeoclimate simulations?

    , Journal of Quaternary Science, Vol: 31, Pages: 363-385, ISSN: 1099-1417

    There has been a gradual evolution in the way that palaeoclimate modelling and palaeoenvironmental data are used together to understand how the Earth System works, from an initial and largely descriptive phase through explicit hypothesis testing to diagnosis of underlying mechanisms. Analyses of past climate states are now regarded as integral to the evaluation of climate models, and have become part of the toolkit used to assess the likely realism of future projections. Palaeoclimate assessment has demonstrated that changes in large-scale features of climate that are governed by the energy and water balance show consistent responses to changes in forcing in different climate states, and these consistent responses are reproduced by climate models. However, state-of-the-art models are still largely unable to reproduce observed changes in climate at a regional scale reliably. While palaeoclimate analyses of state-of-the-art climate models suggest an urgent need for model improvement, much work is also needed on extending and improving palaeoclimate reconstructions and quantifying and reducing both numerical and interpretative uncertainties.

  • Journal article
    Derin Y, Anagnostou E, Berne A, Borga M, Boudevillain B, Buytaert W, Chang CH, Delrieu G, Hong Y, Hsu YC, Lavado-Casimiro W, Manz B, Moges S, Nikolopoulos EI, Sahlu D, Salerno F, Rodríguez-Sánchez JP, Vergara HJ, Yilmaz KKet al., 2016,

    Multiregional Satellite Precipitation Products Evaluation over Complex Terrain

    , Journal of Hydrometeorology, Vol: 17, Pages: 1817-1836, ISSN: 1525-755X

    An extensive evaluation of nine global-scale high-resolution satellite-based rainfall (SBR) products is performed using a minimum of 6 years (within the period of 2000-13) of reference rainfall data derived from rain gauge networks in nine mountainous regions across the globe. The SBR products are compared to a recently released global reanalysis dataset from the European Centre for Medium-Range Weather Forecasts (ECMWF). The study areas include the eastern Italian Alps, the Swiss Alps, the western Black Sea of Turkey, the French Cévennes, the Peruvian Andes, the Colombian Andes, the Himalayas over Nepal, the Blue Nile in East Africa, Taiwan, and the U.S. Rocky Mountains. Evaluation is performed at annual, monthly, and daily time scales and 0.25° spatial resolution. The SBR datasets are based on the following retrieval algorithms: Tropical Rainfall Measuring Mission Multisatellite Precipitation Analysis (TMPA), the NOAA/Climate Prediction Center morphing technique (CMORPH), Precipitation Estimation from Remotely Sensed Information Using Artificial Neural Networks (PERSIANN), and Global Satellite Mapping of Precipitation (GSMaP). SBR products are categorized into those that include gauge adjustment versus unadjusted. Results show that performance of SBR is highly dependent on the rainfall variability. Many SBR products usually underestimate wet season and overestimate dry season precipitation. The performance of gauge adjustment to the SBR products varies by region and depends greatly on the representativeness of the rain gauge network.

  • Journal article
    Parpas P, Rustem, Duy VN Luong, Rueckert, Parpas P, Luong, Rustem, Rueckertet al., 2016,

    A weighted Mirror Descent algorithm for nonsmooth convex optimization problem

    , Journal of Optimization Theory and Applications, Vol: 170, Pages: 900-915, ISSN: 1573-2878

    Large scale nonsmooth convex optimization is a common problemfor a range of computational areas including machine learning and computer vision. Problems in these areas contain special domain structures and characteristics. Special treatment of such problem domains, exploiting their structures, can significantly reduce the computational burden. In this paper, we consider a Mirror Descent method with a special choice of distance function for solving nonsmooth optimization problems over a Cartesian product of convex sets. We propose to use a nonlinear weighted distance in the projectionstep. The convergence analysis identifies optimal weighting parameters that, eventually, lead to the optimally weighted step-size strategy for every projection on a corresponding convex set. We show that the optimality bound of the Mirror Descent algorithm using the weighted distance is either an improvement to, or in the worst-case as good as, the optimality bound of the Mirror Descent using unweighted distances. We demonstrate the efficiency of the algorithm by solving the Markov Random Fields (MRF) optimization problem. In order to exploit the domain of the MRF problem, we use a weighted logentropy distance and a weighted Euclidean distance. Promising experimentalresults demonstrate the effectiveness of the proposed method.

  • Journal article
    Kwan GF, Mayosi BM, Mocumbi AO, Miranda JJ, Ezzati M, Jain Y, Robles G, Benjamin EJ, Subramanian SV, Bukhman Get al., 2016,

    Endemic Cardiovascular Diseases of the Poorest Billion

    , Circulation, Vol: 133, Pages: 2561-2575, ISSN: 0009-7322
  • Journal article
    Scheelbeek PF, Khan AE, Mojumder S, Elliott P, Vineis Pet al., 2016,

    Drinking Water Sodium and Elevated Blood Pressure of Healthy Pregnant Women in Salinity-Affected Coastal Areas

    , Hypertension, Vol: 68, Pages: 464-470, ISSN: 1524-4563

    Coastal areas in Southeast Asia are experiencing high sodium concentrations in drinking water sources that are commonly consumed by local populations. Salinity problems caused by episodic cyclones and subsequent seawater inundations are likely (partly) related to climate change and further exacerbated by changes in upstream river flow and local land-use activities. Dietary (food) sodium plays an important role in the global burden of hypertensive disease. It remains unknown, however, if sodium in drinking water-rather than food-has similar effects on blood pressure and disease risk. In this study, we examined the effect of drinking water sodium on blood pressure of pregnant women: increases in blood pressure in this group could severely affect maternal and fetal health. Data on blood pressure, drinking water source, and personal, lifestyle, and environmental confounders was obtained from 701 normotensive pregnant women residing in coastal Bangladesh. Generalized linear mixed regression models were used to investigate association of systolic and diastolic blood pressure of these-otherwise healthy-women with their water source. After adjustment for confounders, drinkers of tube well and pond water (high saline sources) were found to have significantly higher average systolic (+4.85 and +3.62 mm Hg) and diastolic (+2.30 and +1.72 mm Hg) blood pressures than rainwater drinkers. Drinking water salinity problems are expected to exacerbate in the future, putting millions of coastal people-including pregnant women-at increased risk of hypertension and associated diseases. There is an urgent need to further explore the health risks associated to this understudied environmental health problem and feasibility of possible adaptation strategies.

  • Conference paper
    Heuberger CF, Staffell I, Shah N, Mac Dowell Net al., 2016,

    Levelised Value of Electricity - A Systemic Approach to Technology Valuation

    , 26th European Symposium on Computer Aided Process Engineering - ESCAPE 26
  • Conference paper
    Jacobs CT, Piggott MD, Kramer SC, Funke SWet al., 2016,

    On the validity of tidal turbine array configurations obtained from steady-state adjoint optimisation

    , VII European Congress on Computational Methods in Applied Sciences and Engineering, Publisher: ECCOMAS Proceedia, Pages: 8247-8261

    Extracting the optimal amount of power from an array of tidal turbines requires an intricate understanding of tidal dynamics and the effects of turbine placement on the local and regional scale flow. Numerical models have contributed significantly towards this understanding, and more recently, adjoint-based modelling has been employed to optimise the positioning of the turbines in an array in an automated way and improve on simple man-made configurations (e.g. structured grids of turbines) [1]. Adjoint-based optimisation of high-resolution and ideally 3D transient models is generally a very computationally expensive problem. Multiple approaches are therefore used in practice to obtain feasible runtimes: using high viscosity values to obtain a steady-state solution, or a sequence of steady-state solutions for "time-varying" setups; limiting the number of adjoint computations; or reformulating the problem to allow for coarser mesh resolution to make it feasible for resources assessment (e.g. [2] , [3]). However, such compromises may affect the reliability of the modelled turbines, their wakes and interactions, and thus bring into question the validity of the computed optimal turbine positions. This work considers a suite of idealised simulations of flow past tidal turbine arrays in a two-dimensional channel. It compares four regular array configurations, detailed by Divett et al. [4] , with the configuration found through adjoint optimisation in a steady-state, high-viscosity setup. The optimised configuration produces considerably more power than the other configurations (approximately 40% more than the best man-made configuration). The same configurations are then used to produce a suite of transient simulations that do not use constant high-viscosity, and instead use large eddy simulation (LES) to parameterise the resulting turbulent structures. All simulations are performed using OpenTidalFarm [1]. It is shown that the 'low background viscosity'/LES simu

  • Journal article
    Hylton N, Hinrichsen TF, Vaquero-Stainer AR, Yoshida M, Pusch A, Hopkinson M, Hess O, Phillips CC, Ekins-Daukes NJet al., 2016,

    Photoluminescence upconversion at GaAs/InGaP2 interfaces driven by a sequential two-photon absorption mechanism

    , Physical Review B, Vol: 93, ISSN: 2469-9950

    This paper reports on the results of an investigation into the nature of photoluminescence upconversion at GaAs/InGaP2 interfaces. Using a dual-beam excitation experiment, we demonstrate that the upconversion in our sample proceeds via a sequential two-photon optical absorption mechanism. Measurements of photoluminescence and upconversion photoluminescence revealed evidence of the spatial localization of carriers in the InGaP2 material, arising from partial ordering of the InGaP2. We also observed the excitation of a two-dimensional electron gas at the GaAs/InGaP2 heterojunction that manifests as a high-energy shoulder in the GaAs photoluminescence spectrum. Furthermore, the results of upconversion photoluminescence excitation spectroscopy demonstrate that the photon energy onset of upconversion luminescence coincides with the energy of the two-dimensional electron gas at the GaAs/InGaP2 interface, suggesting that charge accumulation at the interface can play a crucial role in the upconversion process.

  • Journal article
    Dong J, Wu X, Chen Y, Brandon N, Li X, Yang J, Yu J, Zhang W, Hu Y, Yu W, Wang J, Liang S, Hu J, Hou H, Liu B, Yang Cet al., 2016,

    A study on Pb2+/Pb electrodes for soluble lead redox flow cells prepared with methanesulfonic acid and recycled lead

    , Journal of Applied Electrochemistry, Vol: 46, Pages: 861-868, ISSN: 1572-8838

    Electrodeposition and electrodissolution reactionsof the Pb2?/Pb electrode were studied on a glassy carbonrotating disk electrode in aqueous solutions of CH3SO3H andPb(CH3SO3)2. The electrolytic parameters, kinematic viscosityand ionic conductivity, were determined with variousconcentrations of CH3SO3H and Pb(CH3SO3)2. The diffusioncoefficient of Pb2? in this electrolyte prepared with CH3SO3Hwas determined by the Levich Equation. Both the concentrationsof CH3SO3H and Pb(CH3SO3)2 were found responsiblefor the equilibrium potential shifts and exchange currentdensity variations. The electrochemical processes at the Pb2?/Pb electrode were identified as being under mixed ohmicdiffusioncontrol. The electrolyte conductivity and the ionicactivity of Pb2? were recognized as important parameters fordesigning the soluble lead redox flow cells. During constantcurrent charge–discharge measurement, the specific capacityof the Pb2?/Pb electrode was about 253 mAh g-1Pb, about98 % of the theoretical value. The impurity elements Fe, Ba,Al, and Zn in the Pb2? electrolytes prepared with recycledlead exhibited insignificant influences on the Pb2?/Pb reactions.It is reasonable to believe that the recycled lead can beapplied in soluble lead redox flow batteries, and the cost maybe further reduced with recycled lead because expensiveimpurity-control processes seemed to be avoidable.

  • Journal article
    Gambhir A, Sandwell P, Nelson J, 2016,

    The future costs of OPV - A bottom-up model of material and manufacturing costs with uncertainty analysis

    , Solar Energy Materials and Solar Cells, Vol: 156, Pages: 49-58, ISSN: 0927-0248

    Organic photovoltaic (OPV) technology has the potential to provide cheap solar electricity, given advances in low-cost production and module efficiency and lifetime. However, several uncertainties remain in terms of the future costs of OPV modules, which depend on future material and manufacturing costs, as well as key performance characteristics. This assessment takes an engineering-based approach to assessing the potential future cost of each component of OPV modules, as well as the future scale of OPV production plants and associated scale economies, using stochastic analysis to account for uncertainty. The analysis suggests that OPV module costs could fall within a (interquartile) range of US$0.23–0.34/Wp, with a median cost estimate of US$0.28/Wp in the near-term, with future costs most sensitive to manufacturing scale, cell efficiency and module fill factor. This compares to a projected range of module costs for more established PV technologies (crystalline silicon, cadmium telluride and copper indium gallium selenide) of US$0.35–0.6/Wp by 2020. In levelised cost of electricity terms, OPV could compete with the established technologies in both roof- and ground-mounted systems if it can achieve a 10-year lifetime.

  • Journal article
    Sikarwar VS, Zhao M, Clough P, Yao J, Zhong X, Memon MZ, Shah N, Anthony EJ, Fennell PSet al., 2016,

    An overview of advances in biomass gasification

    , Energy and Environmental Science, Vol: 9, Pages: 2939-2977, ISSN: 1754-5692

    Biomass gasification is a widely used thermochemical process for obtaining products with more value and potential applications than the raw material itself. Cutting-edge, innovative and economical gasification techniques with high efficiencies are a prerequisite for the development of this technology. This paper delivers an assessment on the fundamentals such as feedstock types, the impact of different operating parameters, tar formation and cracking, and modelling approaches for biomass gasification. Furthermore, the authors comparatively discuss various conventional mechanisms for gasification as well as recent advances in biomass gasification. Unique gasifiers along with multi-generation strategies are discussed as a means to promote this technology into alternative applications, which require higher flexibility and greater efficiency. A strategy to improve the feasibility and sustainability of biomass gasification is via technological advancement and the minimization of socio-environmental effects. This paper sheds light on diverse areas of biomass gasification as a potentially sustainable and environmentally friendly technology.

  • Journal article
    Hallett TB, Anderson S-J, Asante CA, Bartlett N, Bendaud V, Bhatt S, Burgert CR, Cuadros DF, Dzangare J, Fecht D, Gething PW, Ghys PD, Guwani JM, Heard NJ, Kalipeni E, Kandala N-B, Kim AA, Kwao ID, Larmarange J, Manda SOM, Moise IK, Montana LS, Mwai DN, Mwalili S, Shortridge A, Tanser F, Wanyeki I, Zulu Let al., 2016,

    Evaluation of geospatial methods to generate subnational HIV prevalence estimates for local level planning

    , AIDS, Vol: 30, Pages: 1467-1474, ISSN: 0269-9370

    Objective: There is evidence of substantial subnational variation in the HIV epidemic. However, robust spatial HIV data are often only available at high levels of geographic aggregation and not at the finer resolution needed for decision making. Therefore, spatial analysis methods that leverage available data to provide local estimates of HIV prevalence may be useful. Such methods exist but have not been formally compared when applied to HIV.Design/methods: Six candidate methods – including those used by the Joint United Nations Programme on HIV/AIDS to generate maps and a Bayesian geostatistical approach applied to other diseases – were used to generate maps and subnational estimates of HIV prevalence across three countries using cluster level data from household surveys. Two approaches were used to assess the accuracy of predictions: internal validation, whereby a proportion of input data is held back (test dataset) to challenge predictions; and comparison with location-specific data from household surveys in earlier years.Results: Each of the methods can generate usefully accurate predictions of prevalence at unsampled locations, with the magnitude of the error in predictions similar across approaches. However, the Bayesian geostatistical approach consistently gave marginally the strongest statistical performance across countries and validation procedures.Conclusions: Available methods may be able to furnish estimates of HIV prevalence at finer spatial scales than the data currently allow. The subnational variation revealed can be integrated into planning to ensure responsiveness to the spatial features of the epidemic. The Bayesian geostatistical approach is a promising strategy for integrating HIV data to generate robust local estimates.

  • Journal article
    Huang X, Restuccia F, Gramola M, Rein Get al., 2016,

    Experimental study of the formation and collapse of an overhang in the lateral spread of smouldering peat fires

    , Combustion and Flame, Vol: 168, Pages: 393-402, ISSN: 0010-2180

    Smouldering combustion is the driving phenomenon of wildfires in peatlands, and is responsible for large amounts of carbon emissions and haze episodes world wide. Compared to flaming fires, smouldering is slow, low-temperature, flameless, and most persistent, yet it is poorly understood. Peat, as a typical organic soil, is a porous and charring natural fuel, thus prone to smouldering. The spread of smouldering peat fire is a multidimensional phenomenon, including two main components: in-depth vertical and surface lateral spread. In this study, we investigate the lateral spread of peat fire under various moisture and wind conditions. Visual and infrared cameras as well as a thermocouple array are used to measure the temperature profile and the spread rate. For the first time the overhang, where smouldering spreads fastest beneath the free surface, is observed in the laboratory, which helps understand the interaction between oxygen supply and heat losses. The periodic formation and collapse of overhangs is observed. The overhang thickness is found to increase with moisture and wind speed, while the spread rate decreases with moisture and increases with wind speed. A simple theoretical analysis is proposed and shows that the formation of overhang is caused by the spread rate difference between the top and lower peat layers as well as the competition between oxygen supply and heat losses.

  • Conference paper
    Mumford J, DeVos Y, Liu Y, Mestagh S, Waigmann Eet al., 2016,

    EFSA guidelines on environmental risk assessment of GM animals, including insects

    , GMOs in Integrated Plant Production, Publisher: IOBC, Pages: 39-46, ISSN: 0253-1100

    Future applications for the marketing of genetically modified organisms (GMOs) in the EU may include food/feed products derived from genetically modified (GM) animals, and the release of GM animals, including insects, into the environment. Efforts towards the development of GM insects to control insect vectors of human diseases and manage agricultural pests have progressed substantially with various GM insect × trait combinations in the development pipeline. As a proactive measure, the scientific GMO Panel of the European Food Safety Authority (EFSA) has developed guidelines on: (1) the risk assessment of food/feed derived from GM animals including animal health and welfare aspects; and (2) the environmental risk assessment (ERA) of living GM animals, including insects, released into the environment for commercial purposes. The latter assists applicants in the preparation and presentation of their applications by describing the elements and data requirements for a structured ERA of GM insects consistent with the current Directive 2001/18/EC. A dedicated Working Group (WG) was involved in the elaboration of the ERA guidelines on GM insects, which underwent a public consultation before their finalisation. Relevant comments received were considered by the WG. The WG also took into account the external scientific report on GM insects commissioned by EFSA (Benedict et al., 2010). This report provided background information by mapping relevant fields of expertise and identified essential elements to be considered when performing an ERA of GM insects. Content and stakeholder involvement for the EFSA guidelines are presented.

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