Modelling of redox flow battery electrode processes at a range of length scales : a review

In this article, the different approaches reported in the literature for modelling electrode processes in redox flow batteries (RFBs) are reviewed. RFB models vary widely in terms of computational complexity, research scalability and accuracy of predictions. Development of RFB models have been quite slow in the past, but in recent years researchers have reported on a range of modelling approaches for RFB system optimisation. Flow and transport processes, and their influence on electron transfer kinetics, play an important role in the performance of RFBs. Macro-scale modelling, typically based on a continuum approach for porous electrode modelling, have been used to investigate current distribution, to optimise cell design and to support techno-economic analyses. Microscale models have also been developed to investigate the transport properties within porous electrode materials. These microscale models exploit experimental tomographic techniques to characterise three-dimensional structures of different electrode materials. New insights into the effect of the electrode structure on transport processes are being provided from these new approaches. Modelling flow, transport, electrical and electrochemical processes within the electrode structure is a developing area of research, and there are significant variations in the model requirements for different redox systems, in particular for multiphase chemistries (gas–liquid, solid–liquid, etc.) and for aqueous and non-aqueous solvents. Further development is essential to better understand the kinetic and mass transport phenomena in the porous electrodes, and multiscale approaches are also needed to enable optimisation across the relevent length scales

Velocity-space sensitivity of the time-of-flight neutron spectrometer at JET

The velocity-space sensitivities of fast-ion diagnostics are often described by so-called weight functions. Recently, we formulated weight functions showing the velocity-space sensitivity of the often dominant beam-target part of neutron energy spectra. These weight functions for neutron emission spectrometry (NES) are independent of the particular NES diagnostic. Here we apply these NES weight functions to the time-of-flight spectrometer TOFOR at JET. By taking the instrumental response function of TOFOR into account, we calculate time-of-flight NES weight functions that enable us to directly determine the velocity-space sensitivity of a given part of a measured time-of-flight spectrum from TOFOR

Taxonomic and Geographic Bias in Conservation Biology Research: A Systematic Review of Wildfowl Demography Studies.

Demographic data are important to wildlife managers to gauge population health, to allow populations to be utilised sustainably, and to inform conservation efforts. We analysed published demographic data on the world's wildfowl to examine taxonomic and geographic biases in study, and to identify gaps in knowledge. Wildfowl (order: Anseriformes) are a comparatively well studied bird group which includes 169 species of duck, goose and swan. In all, 1,586 wildfowl research papers published between 1911 and 2010 were found using Web of Knowledge (WoK) and Google Scholar. Over half of the research output involved just 15 species from seven genera. Research output was strongly biased towards 'high income' countries, common wildfowl species, and measures of productivity, rather than survival and movement patterns. There were significantly fewer demographic data for the world's 31 threatened wildfowl species than for non-threatened species. Since 1994, the volume of demographic work on threatened species has increased more than for non-threatened species, but still makes up only 2.7% of total research output. As an aid to research prioritisation, a metric was created to reflect demographic knowledge gaps for each species related to research output for the species, its threat status, and availability of potentially useful surrogate data from congeneric species. According to the metric, the 25 highest priority species include thirteen threatened taxa and nine species each from Asia and South America, and six from Africa

Relationship of edge localized mode burst times with divertor flux loop signal phase in JET

A phase relationship is identified between sequential edge localized modes (ELMs) occurrence times in a set of H-mode tokamak plasmas to the voltage measured in full flux azimuthal loops in the divertor region. We focus on plasmas in the Joint European Torus where a steady H-mode is sustained over several seconds, during which ELMs are observed in the Be II emission at the divertor. The ELMs analysed arise from intrinsic ELMing, in that there is no deliberate intent to control the ELMing process by external means. We use ELM timings derived from the Be II signal to perform direct time domain analysis of the full flux loop VLD2 and VLD3 signals, which provide a high cadence global measurement proportional to the voltage induced by changes in poloidal magnetic flux. Specifically, we examine how the time interval between pairs of successive ELMs is linked to the time-evolving phase of the full flux loop signals. Each ELM produces a clear early pulse in the full flux loop signals, whose peak time is used to condition our analysis. The arrival time of the following ELM, relative to this pulse, is found to fall into one of two categories: (i) prompt ELMs, which are directly paced by the initial response seen in the flux loop signals; and (ii) all other ELMs, which occur after the initial response of the full flux loop signals has decayed in amplitude. The times at which ELMs in category (ii) occur, relative to the first ELM of the pair, are clustered at times when the instantaneous phase of the full flux loop signal is close to its value at the time of the first ELM

Defining Genetic and environmental determinants of elemental homeostasis in maize (Zea mays L.): A genome-wide association study of elemental composition of maize grain

Dissolved minerals are absorbed by plants from the soil or other sources, incorporated into seeds, leaves and other tissues that are then consumed by animals and humans, which carry those nutrients up the food chain. Plant-absorbed minerals form the source of 22 elements required by the human body for proper functionality, whether eaten directly or through meat consumption. The proportion of a plant or other organism that forms the inorganic mineral and trace elements is defined as the ionome. Study of the ionome has the potential to affect a wide range of agronomically pertinent areas affecting agriculture and society, including nutrient-use efficiency, toxicology, bio-fortification, bio-availability, bio-remediation and mitigation of toxic metals in the crops we consume. Maize is a model species, well suited to ionomic studies because of the high diversity in genic regions, but is also the most widely grown staple food crop on the planet with significant cultivation on every continent except Antarctica. Maize also provides a diverse collection of germplasm with the feasibility of creating segregating progenies and immortal genotypes through self-fertilization. This dissertation investigates the dynamic nature of field-based maize kernel concentrations of 20 elements in order to simulate ‘real-world’ situations experienced by plants grown as food, but also to reflect a plant’s necessarily complex genetic adaptation to environments. This study utilized both linkage and association mapping on multiple populations, benefiting from advantageous population design and genetic architecture. Analysis across different populations discovered significant genomic regions that co-localized with known and novel candidate genes. For all 20 elements, significant regions were most frequently found in single field locations, ranging between 219 and 7240 regions per element across locations collectively. Nevertheless, some of these regions were discovered in two or more field environments. The occurrence of significant regions found in two or more locations ranged between 19 and 25. Two additional populations provided nearly isogenic backgrounds to investigate regions found to be significant in previous studies. Specifically, these populations provide evidence for the discovery of a cadmium regulator explaining about 23mg/kg difference between haplotypes, localized to a region of chromosome 2. The results from these studies are anticipated to contribute to the understanding of gene action across environments and provide a rich resource for the identification of genes driving elemental accumulation in maize grain, which can be used to create new varieties better suited to feed our changing world

Surface warfare attrition: does ship type make a difference?

This thesis seeks to determine if there is a relationship between ship type and first-term enlisted attrition in the Surface Warfare Navy. The data used in this thesis were taken from the Department of Defense (DOD) Enlisted Master Record (EMR) . Information on male sailors aboard ships with 33 months or less of completed service was extracted from the EMR. Three cohorts were examined—those who joined their first ship in fiscal 1977, 1981, and 1985, respectively. A total of 77,502 personnel serving in 300 ships were analyzed in three data formats: individual ship, ship class, and ship mission category. The results revealed wide variation in attrition rates between individual ships and respective ship classes across different cohorts. In addition, a distinct trend in attrition was observed between ships in different mission categories. For example, oilers generally had the highest rate of attrition across all three cohorts--followed (in order) by amphibious ships, minesweepers, and repair ships with cruisers, destroyers, and frigates having the lowest rate. Further research is recommended to determine the causes for differences in attrition between ship types. Understanding this aspect of enlisted attrition may further aid Navy manpower planners and leaders in reducing personnel attrition and its consequences for the Surface Warfare Navy.http://archive.org/details/surfacewarfareat00kearLieutenant Commander, United States NavyApproved for public release; distribution is unlimited

Interface debonding driven by fluid injection in a cased and cemented wellbore: Modeling and experiments

The integrity of the wellbore completion under injection conditions is vital for the effective, long term storage of carbon dioxide. Here we experimentally demonstrate and mathematically model fluid-driven debonding of the wellbore annulus in order to provide a fundamental basis for well design. We show that self-limiting versus self-sustaining propagation of the annular debonding are distinguished by the sign of a fluid buoyancy parameter that involves a non-trivial relationship between the hydrostatic pressure variation of the fluid with depth and the clamping stress provided by the internally-pressurized casing/cement system. The theory also gives a series of scaling relationships that can be used to predict the rate of growth of the debonding and the fluid flux through the annulus for various growth regimes. The experiments confirm the theoretical predictions of debonding growth rate for the limiting case of zero-buoyancy. We also observe azimuthal debonding extending around 1/2 to 3/4 of the well annulus in the experiments, which is shown to be consistent with physical insights that can be derived from the theoretical model. We conclude that the clamping stress on the well annulus is a critical quantity for hydraulic isolation of the well, and therefore appropriate design of the casing/cement system relative to the intended injection conditions is necessary for the integrity of CO2 injection wells. © 2013 Elsevier Ltd