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  • Journal article
    Hills TP, Gordon F, Florin NH, Fennell PSet al., 2015,

    Statistical analysis of the carbonation rate of concrete

    , CEMENT AND CONCRETE RESEARCH, Vol: 72, Pages: 98-107, ISSN: 0008-8846
  • Journal article
    Staffell I, 2015,

    Zero carbon infinite COP heat from fuel cell CHP

    , Applied Energy, Vol: 147, Pages: 373-385, ISSN: 0306-2619
  • Journal article
    Leguy AMA, Frost JM, McMahon AP, Sakai VG, Kochelmann W, Law C, Li X, Foglia F, Walsh A, O'Regan BC, Nelson J, Cabral JT, Barnes PRFet al., 2015,

    The dynamics of methylammonium ions in hybrid organic-inorganic perovskite solar cells

    , Nature Communications, Vol: 6, ISSN: 2041-1723

    Methylammonium lead iodide perovskite can make high-efficiency solar cells, which also show an unexplained photocurrent hysteresis dependent on the device-poling history. Here we report quasielastic neutron scattering measurements showing that dipolar CH3NH3+ ions reorientate between the faces, corners or edges of the pseudo-cubic lattice cages in CH3NH3PbI3 crystals with a room temperature residence time of ~14 ps. Free rotation, π-flips and ionic diffusion are ruled out within a 1–200-ps time window. Monte Carlo simulations of interacting CH3NH3+ dipoles realigning within a 3D lattice suggest that the scattering measurements may be explained by the stabilization of CH3NH3+ in either antiferroelectric or ferroelectric domains. Collective realignment of CH3NH3+ to screen a device’s built-in potential could reduce photovoltaic performance. However, we estimate the timescale for a domain wall to traverse a typical device to be ~0.1–1 ms, faster than most observed hysteresis.
  • Journal article
    Calvo MM, Prentice IC, 2015,

    Effects of fire and CO2 on biogeography and primary production in glacial and modern climates

    , New Phytologist, Vol: 208, Pages: 987-994, ISSN: 0028-646X

    Dynamic global vegetation models (DGVMs) can disentangle causes and effects in the control of vegetation and fire. We used a DGVM to analyse climate, CO2 and fire influences on biome distribution and net primary production (NPP) in last glacial maximum (LGM) and pre-industrial (PI) times.The Land surface Processes and eXchanges (LPX) DGVM was run in a factorial design with fire ‘off’ or ‘on’, CO2 at LGM (185 ppm) or PI (280 ppm) concentrations, and LGM (modelled) or recent climates. Results were analysed by Stein–Alpert decomposition to separate primary effects from synergies.Fire removal causes forests to expand and global NPP to increase slightly. Low CO2 greatly reduces forest area (dramatically in a PI climate; realistically under an LGM climate) and global NPP. NPP under an LGM climate was reduced by a quarter as a result of low CO2. The reduction in global NPP was smaller at low temperatures, but greater in the presence of fire.Global NPP is controlled by climate and CO2 directly through photosynthesis, but also through biome distribution, which is strongly influenced by fire. Future vegetation simulations will need to consider the coupled responses of vegetation and fire to CO2 and climate.
  • Journal article
    Parkes MA, Refson K, d'Avezac M, Offer GJ, Brandon NP, Harrison NMet al., 2015,

    Chemical descriptors of yttria-stabilized zirconia at low defect concentration: an ab initio study.

    , Journal of Physical Chemistry A, Vol: 119, Pages: 6412-6420, ISSN: 1520-5215

    Yttria-stabilized zirconia (YSZ) is an important oxide ion conductor with applications in solid oxide fuel cells (SOFCs) and oxygen sensing devices. Doping the cubic phase of zirconia (c-ZrO2) with yttria (Y2O3) is isoelectronic, as two Zr(4+) ions are replaced by two Y(3+) ions, plus a charge compensating oxygen vacancy (Ovac). Typical doping concentrations include 3, 8, 10, and 12 mol %. For these concentrations, and all below 40 mol %, no phase with long-range order has been observed in either X-ray or neutron diffraction experiments. The prediction of local defect structure and the interaction between defects is therefore of great interest. This has not been possible to date as the number of possible defect topologies is very large and to perform reliable total energy calculations for all of them would be prohibitively expensive. Previous theoretical studies have only considered a selection of representative structures. In this study, a comprehensive search for low-energy defect structures using a combined classical modeling and density functional theory approach is used to identify the low-energy isolated defect structures at the dilute limit, 3.2 mol %. Through analysis of energetics computed using the best available Born-Mayer-Huggins empirical potential model, a point charge model, DFT, and a local strain energy estimated in the harmonic approximation, the main chemical and physical descriptors that correlate to the low-energy DFT structures are discussed. It is found that the empirical potential model reproduces a general trend of increasing DFT energetics across a series of locally strain relaxed structures but is unreliable both in predicting some incorrect low-energy structures and in finding some metastable structures to be unstable. A better predictor of low-energy defect structures is found to be the total electrostatic energy of a simple point charge model calculated at the unrelaxed geometries of the defects. In addition, the strain relaxation energ
  • Journal article
    Xu LJ, Chu W, Graham N, 2015,

    Sonophotolytic degradation of phthalate acid esters in water and wastewater: Influence of compound properties and degradation mechanisms

    , JOURNAL OF HAZARDOUS MATERIALS, Vol: 288, Pages: 43-50, ISSN: 0304-3894
  • Journal article
    Leguy AMA, Hu Y, Campoy-Quiles M, Isabel Alonso M, Weber OJ, Azarhoosh P, van Schilfgaarde M, Weller MT, Bein T, Nelson J, Docampo P, Barnes PRFet al., 2015,

    Reversible hydration of CH(3)NH(3)Pbl(3) in films, single crystals, and solar cells

    , Chemistry of Materials, Vol: 27, Pages: 3397-3407, ISSN: 0897-4756

    Solar cells composed of methylammonium lead iodide perovskite (MAPI) are notorious for their sensitivity to moisture. We show that (i) hydrated crystal phases are formed when MAPI is exposed to water vapor at room temperature and (ii) these phase changes are fully reversed when the material is subsequently dried. The reversible formation of CH3NH3PbI3·H2O followed by (CH3NH3)4PbI6·2H2O (upon long exposure times) was observed using time-resolved XRD and ellipsometry of thin films prepared using “solvent engineering”, single crystals, and state-of-the-art solar cells. In contrast to water vapor, the presence of liquid water results in the irreversible decomposition of MAPI to form PbI2. MAPI changes from dark brown to transparent on hydration; the precise optical constants of CH3NH3PbI3·H2O formed on single crystals were determined, with a bandgap at 3.1 eV. Using the single-crystal optical constants and thin-film ellipsometry measurements, the time-dependent changes to MAPI films exposed to moisture were modeled. The results suggest that the monohydrate phase forms independent of the depth in the film, suggesting rapid transport of water molecules along grain boundaries. Vapor-phase hydration of an unencapsulated solar cell (initially Jsc ≈ 19 mA cm–2 and Voc ≈ 1.05 V at 1 sun) resulted in more than a 90% drop in short-circuit photocurrent and ∼200 mV loss in open-circuit potential; however, these losses were fully reversed after the device was exposed to dry nitrogen for 6 h. Hysteresis in the current–voltage characteristics was significantly increased after this dehydration, which may be related to changes in the defect density and morphology of MAPI following recrystallization from the hydrate. Based on our observations, we suggest that irreversible decomposition of MAPI in the presence of water vapor only occurs significantly once a grain has been fully converted to the monohydrate phase.
  • Conference paper
    Mechleri E, rivotti P, mac Dowell N, thornhill Net al., 2015,

    Flexibility issues and controllability analysis of a post-combustion CO2 capture plant integrated with a natural gas power plant

    , 8th Trondheim Conference on CO2 Capture, Transport and Storage (TCCS-8)
  • Journal article
    Zhao R, Zhuge W, Zhang Y, Yang M, Martinez-Botas R, Yin Yet al., 2015,

    Study of two-stage turbine characteristic and its influence on turbo-compound engine performance

    , ENERGY CONVERSION AND MANAGEMENT, Vol: 95, Pages: 414-423, ISSN: 0196-8904
  • Conference paper
    Ritson JP, Graham NJD, Templeton MR, Clark JM, Freeman Cet al., 2015,

    From peat bog to drinking water: ecosystem services under a changing climate

    , British Society of Soil Science Early Careers Research Conference, York, UK
  • Journal article
    Czaja A, Marshall J, 2015,

    Why is there net surface heating over the Antarctic Circumpolar Current?

    , OCEAN DYNAMICS, Vol: 65, Pages: 751-760, ISSN: 1616-7341
  • Journal article
    Hadian S, Madani K, 2015,

    A system of systems approach to energy sustainability assessment: Are all renewables really green?

    , ECOLOGICAL INDICATORS, Vol: 52, Pages: 194-206, ISSN: 1470-160X
  • Journal article
    Hu F, Sun J, Brindley HE, Liang X, Lucyszyn Set al., 2015,

    Systems Analysis for Thermal Infrared '<i>THz Torch</i>' Applications

    , JOURNAL OF INFRARED MILLIMETER AND TERAHERTZ WAVES, Vol: 36, Pages: 474-495, ISSN: 1866-6892
  • Journal article
    Moulds SC, Buytaert W, Mijic A, 2015,

    An open and extensible framework for spatially explicit land use change modelling in R: the lulccR package (0.1.0)

    , Geoscientific Model Development, Vol: 8, Pages: 3359-3402, ISSN: 1991-9603
  • Journal article
    Finegan DP, Scheel M, Robinson JB, Tjaden B, Hunt I, Mason TJ, Millichamp J, Di Michiel M, Offer GJ, Hinds G, Brett DJL, Shearing PRet al., 2015,

    In-operando high-speed tomography of lithium-ion batteries during thermal runaway

    , Nature Communications, Vol: 6, ISSN: 2041-1723
  • Journal article
    Krevor SC, Blunt MJ, Benson SM, Pentland CH, Reynolds CA, Al-Menhali A, Niu Bet al., 2015,

    Capillary trapping for geologic carbon dioxide storage - From pore scale physics to field scale implications

    , International Journal of Greenhouse Gas Control, Vol: 40, Pages: 221-237, ISSN: 1750-5836

    A significant amount of theoretical, numerical and observational work has been published focused on various aspects of capillary trapping in CO2 storage since the IPCC Special Report on Carbon Dioxide Capture and Storage (2005). This research has placed capillary trapping in a central role in nearly every aspect of the geologic storage of CO2. Capillary, or residual, trapping – where CO2 is rendered immobile in the pore space as disconnected ganglia, surrounded by brine in a storage aquifer – is controlled by fluid and interfacial physics at the size scale of rock pores. These processes have been observed at the pore scale in situ using X-ray microtomography at reservoir conditions. A large database of conventional centimetre core scale observations for flow modelling are now available for a range of rock types and reservoir conditions. These along with the pore scale observations confirm that trapped saturations will be at least 10% and more typically 30% of the pore volume of the rock, stable against subsequent displacement by brine and characteristic of water-wet systems. Capillary trapping is pervasive over the extent of a migrating CO2 plume and both theoretical and numerical investigations have demonstrated the first order impacts of capillary trapping on plume migration, immobilisation and CO2 storage security. Engineering strategies to maximise capillary trapping have been proposed that make use of injection schemes that maximise sweep or enhance imbibition. National assessments of CO2 storage capacity now incorporate modelling of residual trapping where it can account for up to 95% of the storage resource. Field scale observations of capillary trapping have confirmed the formation and stability of residually trapped CO2 at masses up to 10,000 tons and over time scales of years. Significant outstanding uncertainties include the impact of heterogeneity on capillary immobilisation and capillary trapping in mixed-wet systems. Overall capillary trapp
  • Journal article
    Parpas P, Ustun B, Webster MD, Tran QKet al., 2015,

    Importance sampling in stochastic programming: A Markov chain Monte Carlo approach

    , Informs Journal on Computing, Vol: 27, Pages: 358-377, ISSN: 1526-5528

    Stochastic programming models are large-scale optimization problems that are used to facilitate decision making under uncertainty. Optimization algorithms for such problems need to evaluate the expected future costs of current decisions, often referred to as the recourse function. In practice, this calculation is computationally difficult as it requires the evaluation of a multidimensional integral whose integrand is an optimization problem. In turn, the recourse function has to be estimated using techniques such as scenario trees or Monte Carlo methods, both of which require numerous functional evaluations to produce accurate results for large-scale problems with multiple periods and high-dimensional uncertainty. In this work, we introduce an importance sampling framework for stochastic programming that can produce accurate estimates of the recourse function using a small number of samples. Our framework combines Markov chain Monte Carlo methods with kernel density estimation algorithms to build a nonparametric importance sampling distribution, which can then be used to produce a lower-variance estimate of the recourse function. We demonstrate the increased accuracy and efficiency of our approach using variants of well-known multistage stochastic programming problems. Our numerical results show that our framework produces more accurate estimates of the optimal value of stochastic programming models, especially for problems with moderate variance, multimodal, or rare-event distributions.
  • Journal article
    Pawar S, 2015,

    The Role of Body Size Variation in Community Assembly

    , Advances in Ecological Research, Vol: 52, Pages: 201-248

    Body size determines key behavioral and life history traits across species, as well as interactions between individuals within and between species. Therefore, variation in sizes of immigrants, by exerting variation in trophic interaction strengths, may drive the trajectory and outcomes of community assembly. Here, I study the effects of size variation in the immigration pool on assembly dynamics and equilibrium distributions of sizes and consumer–resource size-ratios using a general mathematical model. I find that because small sizes both, improve the ability to invade and destabilize the community, invasibility and stability pull body size distributions in opposite directions, favoring an increase in both size and size-ratios during assembly, and ultimately yielding a right-skewed size and a symmetric size-ratio distribution. In many scenarios, the result at equilibrium is a systematic increase in body sizes and size-ratios with trophic level. Thus these patterns in size structure are ‘signatures’ of dynamically constrained, non-neutral community assembly. I also show that for empirically feasible distributions of body sizes in the immigration pool, immigration bias in body sizes cannot counteract dynamical constraints during assembly and thus signatures emerge consistently. I test the theoretical predictions using data from nine terrestrial and aquatic communities and find strong evidence that natural communities do indeed exhibit such signatures of dynamically constrained assembly. Overall, the results provide new measures to detect general, non-neutral patterns in community assembly dynamics, and show that in general, body size is dominant trait that strongly influences assembly and recovery of natural communities and ecosystems.
  • Conference paper
    Ritson JP, Graham NJD, Templeton MR, Freeman C, Clark JMet al., 2015,

    The sensitivity of peat soil and peatland vegetation to drought: release of dissolved organic carbon (DOC) on rewetting

    , European Geosciences Union (EGU) General Assembly, Vienna, Austria
  • Journal article
    Mostafavi N, Vlaanderen J, Chadeau-Hyam M, Beelen R, Modig L, Palli D, Bergdahl IA, Vineis P, Hoek G, Kyrtopoulos SA, Vermeulen Ret al., 2015,

    Inflammatory markers in relation to long-term air pollution

    , Environment International, Vol: 81, Pages: 1-7, ISSN: 0160-4120

    Long-term exposure to ambient air pollution can lead to chronic health effects such as cancer, cardiovascular and respiratory disease. Systemic inflammation has been hypothesized as a putative biological mechanism contributing to these adverse health effects. We evaluated the effect of long-term exposure to air pollution on blood markers of systemic inflammation.We measured a panel of 28 inflammatory markers in peripheral blood samples from 587 individuals that were biobanked as part of a prospective study. Participants were from Varese and Turin (Italy) and Umea (Sweden). Long-term air pollution estimates of nitrogen oxides (NOx) were available from the European Study of Cohorts for Air Pollution Effects (ESCAPE). Linear mixed models adjusted for potential confounders were applied to assess the association between NOx and the markers of inflammation.Long-term exposure to NOx was associated with decreased levels of interleukin (IL)-2, IL-8, IL-10 and tumor necrosis factor-α in Italy, but not in Sweden. NOx exposure levels were considerably lower in Sweden than in Italy (Sweden: median (5th, 95th percentiles) 6.65 μg/m3 (4.8, 19.7); Italy: median (5th, 95th percentiles) 94.2 μg/m3 (7.8, 124.5)). Combining data from Italy and Sweden we only observed a significant association between long-term exposure to NOx and decreased levels of circulating IL-8.We observed some indication for perturbations in the inflammatory markers due to long-term exposure to NOx. Effects were stronger in Italy than in Sweden, potentially reflecting the difference in air pollution levels between the two cohorts.
  • Journal article
    Fayle TM, Turner EC, Basset Y, Ewers RM, Reynolds G, Novotny Vet al., 2015,

    Whole-ecosystem experimental manipulations of tropical forests

    , Trends in Ecology and Evolution, Vol: 30, Pages: 334-346, ISSN: 1872-8383

    Tropical forests are highly diverse systems involving extraordinary numbers of interactions between species, with each species responding in a different way to the abiotic environment. Understanding how these systems function and predicting how they respond to anthropogenic global change is extremely challenging. We argue for the necessity of ‘whole-ecosystem’ experimental manipulations, in which the entire ecosystem is targeted, either to reveal the functioning of the system in its natural state or to understand responses to anthropogenic impacts. We survey the current range of whole-ecosystem manipulations, which include those targeting weather and climate, nutrients, biotic interactions, human impacts, and habitat restoration. Finally we describe the unique challenges and opportunities presented by such projects and suggest directions for future experiments.
  • Journal article
    Xenos DP, Cicciotti M, Kopanos GM, Bouaswaig AEF, Kahrs O, Martinez-Botas R, Thornhill NFet al., 2015,

    Optimization of a network of compressors in parallel: Real Time Optimization (RTO) of compressors in chemical plants - An industrial case study

    , Applied Energy, Vol: 144, Pages: 51-63, ISSN: 0306-2619

    The aim of this paper is to present a methodology for optimizing the operation of compressors in parallel in process industries. Compressors in parallel can be found in many applications for example in compressor stations conveying gas through long pipelines and in chemical plants in which compressors supply raw or processed materials to downstream processes. The current work presents an optimization framework for compressor stations which describe integration of a short term and a long term optimization approach. The short-term part of the framework suggests the best distribution of the load of the compressors (where the time scale is minutes) and the long-term optimization provides the scheduling of the compressors for large time periods (where the time scale is days). The paper focuses on the short-term optimization and presents a Real Time Optimization (RTO) framework which exploits process data in steady-state operation to develop regression models of compressors. An optimization model employs the updated steady-state models to estimate the best distribution of the load of the compressors to reduce power consumption and therefore operational costs. The paper demonstrates the application of the RTO to a network of parallel industrial multi-stage centrifugal compressors, part of a chemical process in BASF SE, Germany. The results from the RTO application showed a reduction in power consumption compared to operation with equal load split strategy.
  • Journal article
    Ewers RM, Boyle MJW, Gleave RA, Plowman NS, Benedick S, Bernard H, Bishop TR, Bakhtiar EY, Vun KC, Chung AYC, Davies RG, Edwards DP, Eggleton P, Fayle TM, Hardwick SR, Homathevi R, Kitching RL, Khoo MS, Luke SH, March JJ, Nilus R, Pfeifer M, Rao SV, Sharp AC, Snaddon JL, Stork NE, Struebig MJ, Wearn OR, Yusah KM, Turner ECet al., 2015,

    Logging cuts the functional importance of invertebrates in tropical rainforest

    , Nature Communications, Vol: 6, Pages: 1-7, ISSN: 2041-1723

    Invertebrates are dominant species in primary tropical rainforests, where their abundance and diversity contributes to the functioning and resilience of these globally important ecosystems. However, more than one-third of tropical forests have been logged, with dramatic impacts on rainforest biodiversity that may disrupt key ecosystem processes. We find that the contribution of invertebrates to three ecosystem processes operating at three trophic levels (litter decomposition, seed predation and removal, and invertebrate predation) is reduced by up to one-half following logging. These changes are associated with decreased abundance of key functional groups of termites, ants, beetles and earthworms, and an increase in the abundance of small mammals, amphibians and insectivorous birds in logged relative to primary forest. Our results suggest that ecosystem processes themselves have considerable resilience to logging, but the consistent decline of invertebrate functional importance is indicative of a human-induced shift in how these ecological processes operate in tropical rainforests.
  • Journal article
    Melbourne J, Clancy A, Seiffert J, Skepper J, Tetley TD, Shaffer MS, Porter Aet al., 2015,

    An investigation of the carbon nanotube - Lipid interface and its impact upon pulmonary surfactant lipid function.

    , Biomaterials, Vol: 55, Pages: 24-32, ISSN: 1878-5905

    Multiwalled carbon nanotubes (MWCNTs) are now synthesized on a large scale, increasing the risk of occupational inhalation. However, little is known of the MWCNT-pulmonary surfactant (PS) interface and its effect on PS functionality. The Langmuir-Blodgett trough was used to evaluate the impact of MWCNTs on fundamental properties of PS lipids which influence PS function, i.e. compression resistance and maximum obtainable pressure. Changes were found to be MWCNT length-dependent. 'Short' MWCNTs (1.1 μm, SD = 0.61) penetrated the lipid film, reducing the maximum interfacial film pressure by 10 mN/m (14%) in dipalmitoylphosphatidylcholine (DPPC) and PS, at an interfacial MWCNT-PS lipid mass ratio range of 50:1 to 1:1. 'Long' commercial MWCNTs (2.1 μm, SD = 1.2) caused compression resistance at the same mass loadings. 'Very long' MWCNTs (35 μm, SD = 19) sequestered DPPC and were squeezed out of the DPPC film. High resolution transmission electron microscopy revealed that all MWCNT morphologies formed DPPC coronas with ordered arrangements. These results provide insight into how nanoparticle aspect ratio affects the interaction mechanisms with PS, in its near-native state at the air-water interface.
  • Journal article
    Parham PE, Waldock J, Christophides GK, Hemming D, Agusto F, Evans KJ, Fefferman N, Gaff H, Gumel A, LaDeau S, Lenhart S, Mickens RE, Naumova EN, Ostfeld RS, Ready PD, Thomas MB, Velasco-Hernandez J, Michael Eet al., 2015,

    Climate, environmental and socio-economic change: weighing up the balance in vector-borne disease transmission

    , PHILOSOPHICAL TRANSACTIONS OF THE ROYAL SOCIETY B-BIOLOGICAL SCIENCES, Vol: 370, ISSN: 0962-8436
  • Journal article
    Parham PE, Waldock J, Christophides GK, Michael Eet al., 2015,

    Climate change and vector-borne diseases of humans Preface

    , PHILOSOPHICAL TRANSACTIONS OF THE ROYAL SOCIETY B-BIOLOGICAL SCIENCES, Vol: 370, ISSN: 0962-8436
  • Journal article
    Spathi C, Vandeperre LJ, Cheeseman CR, 2015,

    Production of lightweight fillers from waste glass and paper sludge ash

    , Waste and Biomass Valorization, Vol: 6, Pages: 875-881, ISSN: 1877-265X
  • Journal article
    Newbold T, Hudson LN, Hill SLL, Contu S, Lysenko I, Senior RA, Boerger L, Bennett DJ, Choimes A, Collen B, Day J, De Palma A, Diaz S, Echeverria-Londono S, Edgar MJ, Feldman A, Garon M, Harrison MLK, Alhusseini T, Ingram DJ, Itescu Y, Kattge J, Kemp V, Kirkpatrick L, Kleyer M, Correia DLP, Martin CD, Meiri S, Novosolov M, Pan Y, Phillips HRP, Purves DW, Robinson A, Simpson J, Tuck SL, Weiher E, White HJ, Ewers RM, Mace GM, Scharlemann JPW, Purvis Aet al., 2015,

    Global effects of land use on local terrestrial biodiversity

    , Nature, Vol: 520, Pages: 45-50, ISSN: 0028-0836

    Human activities, especially conversion and degradation of habitats, are causing global biodiversity declines. How local ecological assemblages are responding is less clear—a concern given their importance for many ecosystem functions and services. We analysed a terrestrial assemblage database of unprecedented geographic and taxonomic coverage to quantify local biodiversity responses to land use and related changes. Here we show that in the worst-affected habitats, these pressures reduce within-sample species richness by an average of 76.5%, total abundance by 39.5% and rarefaction-based richness by 40.3%. We estimate that, globally, these pressures have already slightly reduced average within-sample richness (by 13.6%), total abundance (10.7%) and rarefaction-based richness (8.1%), with changes showing marked spatial variation. Rapid further losses are predicted under a business-as-usual land-use scenario; within-sample richness is projected to fall by a further 3.4% globally by 2100, with losses concentrated in biodiverse but economically poor countries. Strong mitigation can deliver much more positive biodiversity changes (up to a 1.9% average increase) that are less strongly related to countries' socioeconomic status.
  • Journal article
    Rhazaoui K, Cai Q, Kishimoto M, Tariq F, Somalu MR, Adjiman CS, Brandon NPet al., 2015,

    Towards the 3D Modelling of the Effective Conductivity of Solid Oxide Fuel Cell Electrodes - Validation against experimental measurements and prediction of electrochemical performance

    , Electrochimica Acta, Vol: 168, Pages: 139-147, ISSN: 1873-3859

    The effective conductivity of thick-film solid oxide fuel cell (SOFC) electrodes plays a key role in their performance. It determines the ability of the electrode to transport charge to/from reaction sites to the current collector and electrolyte. In this paper, the validity of the recently proposed 3D resistor network model for the prediction of effective conductivity, the ResNet model, is investigated by comparison to experimental data. The 3D microstructures of Ni/10ScSZ anodes are reconstructed using tomography through the focused ion beam and scanning electron microscopy (FIB-SEM) technique. This is used as geometric input to the ResNet model to predict the effective conductivities, which are then compared against the experimentally measured values on the same electrodes. Good agreement is observed, supporting the validity of the ResNet model for predicting the effective conductivity of SOFC electrodes. The ResNet model is then combined with the volume-of-fluid (VOF) method to integrate the description of the local conductivity (electronic and ionic) in the prediction of electrochemical performance. The results show that the electrochemical performance is in particular sensitive to the ionic conductivity of the electrode microstructure, highlighting the importance of an accurate description of the local ionic conductivity.
  • Journal article
    Greenbaum JS, Blankenship DD, Young DA, Richter TG, Roberts JL, Aitken ARA, Legresy B, Schroeder DM, Warner RC, van Ommen TD, Siegert MJet al., 2015,

    Ocean access to a cavity beneath Totten Glacier in East Antarctica

    , Nature Geoscience, Vol: 8, Pages: 294-298, ISSN: 1752-0894

    Totten Glacier, the primary outlet of the Aurora Subglacial Basin, has the largest thinning rate in East Antarctica1,2. Thinning may be driven by enhanced basal melting due to ocean processes3, modulated by polynya activity4,5. Warm modified Circumpolar Deep Water, which has been linked to glacier retreat in West Antarctica6, has been observed in summer and winter on the nearby continental shelf beneath 400 to 500 m of cool Antarctic Surface Water7,8. Here we derive the bathymetry of the sea floor in the region from gravity9 and magnetics10 data as well as ice-thickness measurements11. We identify entrances to the ice-shelf cavity below depths of 400 to 500 m that could allow intrusions of warm water if the vertical structure of inflow is similar to nearby observations. Radar sounding reveals a previously unknown inland trough that connects the main ice-shelf cavity to the ocean. If thinning trends continue, a larger water body over the trough could potentially allow more warm water into the cavity, which may, eventually, lead to destabilization of the low-lying region between Totten Glacier and the similarly deep glacier flowing into the Reynolds Trough. We estimate that at least 3.5 m of eustatic sea level potential drains through Totten Glacier, so coastal processes in this area could have global consequences.

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