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Filament seals, such as brush seals and leaf seals, are investigated as a potential improved seal for gas turbine applications. As these seals operate in contact with the rotor, a good understanding of their stiffness is required in order to minimize seal wear and degradation. This paper demonstrates that the filament and complete seal stiffness is affected in comparable magnitudes by mechanical and aerodynamic forces. In certain cases, the aerodynamic forces can also lead to an overall negative seal stiffness which may affect stable seal operation. In negative stiffness, the displacement of the seal or rotor into an eccentric position causes a resultant force, which, rather than restoring the rotor to a central position, acts to amplify its displacement. Insight into the forces acting on the seal filaments is gained by investigating a leaf seal, which consists of a pack of thin planar leaves arranged around the rotor, with coverplates on either side of the leaf pack, offset from the pack surfaces. The leaf seal is chosen due to its geometry being more suitable for analysis compared to alternative filament seals such as the brush seal. Data from two experimental campaigns are presented which show a seal exhibiting negative stiffness and a seal exhibiting a stiffness reduction due to aerodynamic effects. An empirical model for the forces acting on leaf filaments is developed based on the experimental data, which allows separation of mechanical and aerodynamic forces. In addition a numerical model is developed to analyze the flow approaching the leaf pack and the interleaf flow, which gives an insight into the causes of the aerodynamic forces. Using the empirical and numerical models together, a full picture of the forces affecting leaf stiffness is created. Validation of the models is achieved by successfully predicting seal stiffness for a further data set across the full range of operating conditions. The understanding of aerodynamic forces and their impact on filament and seal stiffness allows for their consideration in leaf seal design. A qualitative assessment of how they may be used to improve seal operation in filament seals is given.

A large electrode geometric area-based pyrenyl carbon nanostructure modification for scale-up of electrocatalytic currents and power using hydrogenase anode and bilirubin oxidase cathode is demonstrated.

Abstract Coal-fired gasifiers are the key technology for clean power generation and coal chemical process. This paper presents a 2-stage entrained flow dry powder gasifier in which coal is entrained into the lower chamber burner with oxygen and steam to raise the temperature of the crude gas up to 1700 °C. The lower chamber is linked to the upper gasification chamber through a middle throat, where additional coal and steam is fed to cool down the slag to less than 900 °C for deslagging from the lower chamber bottom. Various coals have been characterized and gasified with this 2-stage entrained flow dry powder gasifier and comparisons made with single stage gasifiers. The results show that the 2-stage gasifier is suitable for a broad range of coal varieties and gives carbon conversion up to 98.9% with cold syngas efficiency of 83.2% at a pressure of 3.0 MPa, while the oxygen and coal consumption are lower than with the single stage gasifier.

Combined complete active space perturbation theory (CASPT2) and multireference configuration interaction calculations with single and double excitations (MR-CISD) were performed in order to explore possible deactivation pathways of thymine after photoexcitation. Equilibrium geometries are reported together with a total of eight extremes (minima or maxima) on the crossing seam (MXS), through which such radiationless transitions may occur. Furthermore, conformational analysis allows grouping these conical intersections in five distinct types. Reaction paths were calculated connecting the S1 (1)n pi* minimum with the lowest-energy MXS of each group. Two distinct types of paths were observed, both with features that should delay the internal conversion to the ground state. This is shown to provide a possible explanation for the relatively long excited-state lifetime of thymine.

Abstract Biofuels have been promoted as a renewable energy option in many countries, but have also faced extensive scrutiny over their sustainability. Food security is perhaps the most debated sustainability impact of biofuels, especially in regions such as Sub-Saharan Africa that experience high rates of malnutrition and have been a major destination for biofuel-related investments. This study assesses the local food security impacts of engagement in biofuel crop production using a consistent protocol between multiple crops and sites. We use standardized metrics of food security related to dietary diversity and perceptions of hunger, and focus on feedstock smallholders and plantation workers in four operational projects: a large-scale jatropha plantation (Mozambique), a smallholder-based jatropha project (Malawi) and two hybrid sugarcane projects (Malawi, Eswatini). Collectively these reflect the main feedstocks, modes of production and land use transitions related to biofuel projects in Sub-Sahara Africa. Inverse Probability Weighting analysis indicates that involvement in sugarcane production improved household food security for plantation workers and feedstock smallholders. Conversely, involvement in jatropha production does not have a statistically significant positive effect on household food security for both workers and smallholders. Regression models indicate that the factors driving food security indicator levels vary between study sites. Wealth indicators influence food security indicators in several sites, but the absolute level of income plays a smaller role, while income stability/regularity, access to credit and stable markets for selling sugarcane be important drivers as indicated by the strong effect of proxy variables on indicators.

AbstractThe signal for climate change effects can be abstruse; consequently, interpretations of evidence must avoid verisimilitude, or else misattribution of causality could compromise policy decisions. Examining climatic effects on wild animal population dynamics requires ability to trap, observe or photograph and to recapture study individuals consistently. In this regard, we use 19 years of data (1994–2012), detailing the life histories on 1179 individual European badgers over 3288 (re‐) trapping events, to test whether trapping efficiency was associated with season, weather variables (both contemporaneous and time lagged), body‐condition index (BCI) and trapping efficiency (TE).PCAfactor loadings demonstrated thatTEwas affected significantly by temperature and precipitation, as well as time lags in these variables. From multi‐model inference,BCIwas the principal driver ofTE, where badgers in good condition were less likely to be trapped. Our analyses exposed that this was enacted mechanistically via weather variables drivingBCI, affectingTE. Notably, the very conditions that militated for poor trapping success have been associated with actual survival and population abundance benefits in badgers. Using these findings to parameterize simulations, projecting best‐/worst‐case scenario weather conditions andBCIresulted in 8.6% ± 4.9SDdifference in seasonalTE, leading to a potential 55.0% population abundance under‐estimation under the worst‐case scenario; 38.6% over‐estimation under the best case. Interestingly, simulations revealed that while any single trapping session might prove misrepresentative of the true population abundance, due to weather effects, prolonging capture–mark–recapture studies under sub‐optimal conditions decreased the accuracy of population estimates significantly. We also use these projection scenarios to explore how weather could impact government‐led trapping of badgers in theUK, in relation toTBmanagement. We conclude that population monitoring must be calibrated against the likelihood that weather conditions could be altering trap success directly, and therefore biasing model design.

In order to mitigate energy crisis and to meet carbon-emission reduction targets, the use of electrical energy produced by solar photovoltaic (PV) is inevitable. To meet the global increasing energy demand, PV power capacity will be expanded ranging from large-scale (from ten to several hundred MWs) PV farms at high and medium voltage level to kilowatt residential PV systems at low voltage level. It is expected that the PV penetration will increase in power systems with the retirement of traditional carbon-emission emitting power plants. Solar energy is diurnal in nature and in practice, it is highly uncertain due to various perturbation effects. With the recent technological advancements and rapid cost reductions in electrical energy storage (EES), EES could be deployed to enhance the system's performance and stability. This paper presents a comprehensive review on the emerging high penetration of PV with an overview of EES for PV systems. The crucial element, the building block of solar panel and the solar cell are reviewed. The emerging cell technologies are presented. A study of solar power forecasting techniques, an important tool for the successful operation and planning of PV and EES is included. A selection of EES is presented and studied for PV system purposes. Future research and areas for improvements in recent works and related areas are identified.

The effect of ethanol on the release and/or intracellular accumulation of lysozyme (LZM) by human monocytes and monocyte-derived macrophages (mø) was investigated in vitro. A reverse haemolytic plaque assay, to detect and quantify LZM release by individual cells was combined with quantitative immunocytochemistry using LZM and the pan-macrophage monoclonal EBM/11 as markers. Ethanol had no effect on monocytes; however it reduced secretion of LZM by a mø subpopulation. Ethanol also reduced both the total number of mø immunoreactive for LZM, (but not EBM/11), and the proportion of LZM-secreting mø containing detectable LZM. The latter was correlated with an increase in the proportion of LZM-secreting mø that were not immunoreactive for this enzyme. These data suggest functional heterogeneity amongst human macrophages with a mø subpopulation which responds to ethanol exposure with a drop in both content and release of LZM. This might have implications for macrophage function in alcoholic liver disease.