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A geometric method for analysis of elastic and elastic-plastic solids is proposed. It involves operators on naturally discrete domains representing a material’s microstructure, rather than the classical discretisation of domains for solving continuum boundary value problems. Discrete microstructures are considered as general cell complexes, which are circumcentre-dual to simplicial cell complexes. The proposed method uses the separation of the total deformation energy into volumetric and distortional parts as a base for introducing elastoplastic material behaviour. Volumetric parts are obtained directly from volume changes of dual cells, and the distortional parts are calculated from the distance changes between primal and dual nodes. First, it is demonstrated that the method can accurately reproduce the elastic behaviour of solids with Poisson’s ratios in the thermodynamically admissible range from -0.99 to 0.49. Further verification of the method is demonstrated by excellent agreement between analytical results and simulations of the elastic deformation of a beam subjected to a vertical displacement. Second, the Prandtl operator approach is used to simulate the behaviour of the solid during cyclic loading, considering its elastoplastic material properties. Results from simulations of cyclic behaviour during alternating and variable load histories are compared to expected macroscopic behaviour as further support to the applicability of the method to elastic-plastic problems.

Purpose of Review This paper assesses social science research relating to BECCS and considers the applicability of research on CCS to BECCS. Recent Findings In recent years, social science research on CCS and BECCS has gone beyond an evaluation of public acceptance to provide a more nuanced analysis of the wider social political, ethical, and governance contexts in which large-scale deployment might be achieved. This raises issues at global, local, and regional scales, requiring a wide array of methods and approaches. Summary Awareness of the scale and urgency needed to act on climate change is growing and the role of BECCS in delivering carbon dioxide removal forms a central argument for the use of this family of technologies. Here, framing becomes a critical factor in how society responds to BECCS technologies and we argue that making the case for BECCS as a means of extending mitigation to make a ‘net zero’ goal achievable could be the key to its acceptable and sustainable deployment.

A semi-submersible wind platform with four floats of equal diameter, damping plates and relatively small drafts has been designed to support a 5 MW wind turbine at full scale. Motion and mooring forces from wave basin measurements have been compared with time domain linear diffraction modelling accounting for drag forces, mooring forces and mean forces due to zero-difference frequency components, as is standard, and due to damping associated with radiation and drag forces, not previously considered. The platform response in the form of rms acceleration is quite well predicted although peak values can be underestimated. The mean mooring forces are underestimated and peak values are considerably underestimated. In large waves moorings experience high snatch loads. The measured mean forces were applied in the model for further comparison. The mooring was primarily designed to prevent drift of the floater and improved designs could eliminate or reduce snatch loads. However, it is shown that hub acceleration is quite moderate, with peak values less than 4 m/s2 in even the largest waves. The rms platform acceleration is largely decoupled from the mooring forces, as shown by corresponding spectra. In extreme conditions hydrodynamic mooring forces require nonlinear effects due to steep, sometimes breaking, waves to be accounted for. The wind thrust is included in the model using a coefficient from blade element momentum theory based on relative wind velocity. The peak hydrodynamic force would be significantly larger than the maximum wind thrust although the mean hydrodynamic force is significantly smaller. A practical conclusion is that a semi-sub floater with damping plates giving sufficiently low accelerations for operation in large waves may be of relatively shallow draft, less than the depths of many ports which is convenient for deployment.

This work describes a local approach to cleavage fracture (LAF) incorporating the statistics of microcracks to characterize the cleavage fracture toughness distribution in structural steels. Fracture toughness testing conducted on standard compact tension C(T) specimens for a 22NiMoCr37 pressure vessel steel provides the cleavage fracture resistance data needed to determine the measured toughness distribution. Metallographic examination of etched surfaces for the tested steel also provides the distribution of carbides, which are assumed as the Griffith fracture-initiating particles, dispersed in the material from which the cleavage fracture toughness distribution is predicted. Overall, the analyses conducted in the present work show that LAFs incorporating the statistics of microcracks are a viable engineering procedure to describe the dependence of fracture toughness on temperature in the DBT region for ferritic steels.

Graphite is a candidate material for Generation IV concepts and is used as a moderator in Advanced Gas-cooled Reactors (AGR) in the UK. Spatial material variability is present within billets causing different material property values between different components. Variations in material properties and irradiation effects can produce stress concentrations and diverse mechanical responses in a nuclear reactor graphite core. In order to characterise the material variability, geostatistical techniques called variography and random field theory were adapted for studying the density and Young's modulus of a billet of Gilsocarbon and NBG-18 graphite grades. Variography is a technique for estimating the distance over which material property values have significant spatial correlation, known as the scale of fluctuation or spatial correlation length. The paper uses random field theory to create models that mimic the original spatial and statistical distributions of the original data set. This study found different values of correlation length for density and Young's modulus around the edges of a Gilsocarbon billet, while in the case of NBG-18, similar correlation lengths where found across the billet. Examples of several random fields are given to reproduce the spatial patterns and values found in the original data.

© 2019 The Royal Society of Chemistry. High electrostrain and breakdown strength (1 - x)BiFeO3-0.3BaTiO3-xNd(Li0.5Nb0.5)O3 (BF-BT-xNLN) ceramics were studied by in situ synchrotron X-ray diffraction (XRD) in combination with Rietveld refinement and conventional transmission electron microscopy. At zero field, compositions transformed from majority ferroelectric rhombohedral to pseudocubic as the NLN concentration increased, with 0.27% strain achieved at 60 kV cm-1 for x = 0.01. The large measured macroscopic strain was commensurate with peak shifting in XRD peak profiles, yielding 0.6% total strain at 150 kV cm-1. Strain anisotropy of ϵ200 > ϵ220 > ϵ111 was observed but despite the large applied field, no peak splitting was detected. We therefore concluded that the large electrostrain is not achieved through a conventional relaxor to field induced long-range ferroelectric transition. Instead, the data supports a model where local polar regions distort in the direction of the applied field within multiple local symmetries (pseudosymmetry) without long range correlation. We proposed that pseudosymmetry is maintained in BF-BT-xNLN even at high field (150 kV cm-1) due to the large ion radii mismatch and competing ionic/covalent bonding between Ba2+ and Bi3+ ions.

Distinctive structure-property relationships are revealed in the relaxor ferroelectric ceramic solid solution, (1-x)K0.5Bi0.5TiO3 - xBiMg0.5Ti0.5O3: 0.02 < x < 0.08. The constructed phase diagram and results of in-situ synchrotron X-ray diffraction provide explanations for temperature and electric field dependent anomalies in dielectric, ferroelectric and electromechanical properties. At room temperature a mixed phase tetragonal and pseudocubic phase field occurs for compositions 0 > x ≤ 0.07. As temperature rises to ≥ 150 °C, the ferroelectric tetragonal relaxor phase changes to a pseudocubic ergodic relaxor phase; this change in length scale of polar order is responsible for an inflection in relative permittivity - temperature plots. The transition is reversed by a sufficient electric field, thereby explaining the constricted form of polarisation-electric field loops measured at >150°C. It is also responsible for a change in slope of the strain-electric field (S-E) plots which are relatively linear in the ferroelectric regime i.e. at temperatures up to 150 °C, giving unipolar strains of 0.11 % at 20 °C and 0.14% at 150 °C (50 kV cm-1 field). The additional contribution from the effect of the field-induced pseudocubic to tetragonal transition, generates strains of ∼ 0.2 % at 185 °C. Unusual for a piezoelectric solid solution, the maximum strains and charge coefficients (d33 =150 pC N-1, 20 °C) do not coincide with a morphotropic or polymorphic phase boundary.

The emergence of untreatable drug-resistant strains of Mycobacterium tuberculosis is a major public health problem worldwide, and the identification of new efficient treatments is urgently needed. Mycobacterium tuberculosis cytochrome P450 CYP121A1 is a promising drug target for the treatment of tuberculosis owing to its essential role in mycobacterial growth. Using a rational approach, which includes molecular modelling studies, three series of azole pyrazole derivatives were designed through two synthetic pathways. The synthesized compounds were biologically evaluated for their inhibitory activity towards M. tuberculosis and their protein binding affinity (KD). Series 3 biarylpyrazole imidazole derivatives were the most effective with the isobutyl (10 f) and tert-butyl (10 g) compounds displaying optimal activity (MIC 1.562 μg/mL, KD 0.22 μM (10 f) and 4.81 μM (10 g)). The spectroscopic data showed that all the synthesised compounds produced a type II red shift of the heme Soret band indicating either direct binding to heme iron or (where less extensive Soret shifts are observed) putative indirect binding via an interstitial water molecule. Evaluation of biological and physicochemical properties identified the following as requirements for activity: LogP >4, H-bond acceptors/H-bond donors 4/0, number of rotatable bonds 5-6, molecular volume >340 Å3, topological polar surface area 2.

The response and power capture of the multi-float wave energy converter M4 has been shown to be approximately predicted by linear diffraction-radiation modelling, giving relatively high capture widths. In this study we model a 6-float configuration which has been investigated experimentally in irregular waves and take account of the mooring system. Second-order mean forces are included due to excitation forces as is standard, but also due to the rate of energy extraction from mechanical damping and radiation damping resulting from body motion. There are also second order effects due to coupling between heave and surge. Operational conditions with mechanical damping and extreme conditions without mechanical damping (giving worst case response) are investigated. The motion is almost independent of mooring forces from a single point mooring, known as slack-moored. In operational conditions mean mooring forces are in approximate agreement with experiment except for larger periods and peak forces are similar. For extreme waves large rotational response is predicted reasonably by linear diffraction-radiation modelling with a small representative drag coefficient, as is horizontal acceleration, although peak values may be underestimated for the largest wave heights. However mean mooring forces are markedly underestimated and peak values generally overestimated. The overall conclusion is that linear modelling gives reasonable prediction of response in all wave conditions, and power capture when operational, but resulting second order mean forces only give approximate predictions for smaller wave heights.

Functional materials’ properties are influenced by microstructures which can be changed during manufacturing. A technique is presented which digitises graphite foam via X-ray tomography and converts it into image-based models to determine properties in silico. By simulating a laser flash analysis its effective thermal conductivity is predicted. Results show ~1 % error in the direction the foam was ‘grown’ during manufacturing but is significantly less accurate in plane due to effective thermal conductivity resulting from both the foam’s microstructure and graphite’s crystalline structure. An empirical relationship is found linking these by using a law of mixtures. A case study is presented demonstrating the technique’s use to simulate a heat exchanger component containing graphite foam with micro-scale accuracy using literature material properties for solid graphite. Compared against conventional finite element modelling there is no requirement to firstly experimentally measure the foam’s effective bulk properties. Additionally, improved local accuracy is achieved due to exact location of contact between the foam and other parts of the component. This capability will be of interest in design and manufacture of components using graphite materials. The software used was developed by the authors and is open source for others to undertake similar studies.

Forced heave and surge motion of axisymmetric vertical cylindrical bodies with flat and rounded bases are simulated using the advanced CFD software STAR-CCM+ where the overset method is used so that the mesh local to the body moves within a stationary outer mesh. Viscous effects generating drag, and also influencing added mass and radiation damping, are determined. The Reynolds-Averaged Navier–Stokes (RANS) equations are adopted with different turbulence closure models and the water surface is captured by the volume of fluid (VOF) method. These results are of basic interest but the main motive is to assess appropriate drag coefficients for use with linear diffraction models of waveenergy converters (WEC) and we have particular interest in the multi-body WEC M4. A basic dynamical model is set up so that drag, added mass and radiation damping coefficients may be obtained from the CFD results. Added mass and radiation damping coefficients were also obtained from the potential flow solver WAMITfor comparison. Mesh convergence studies were undertaken and while mesh independence was achieved for total force it was not possible for the very small shear force. In the laboratory a free heave decay test was undertaken without mechanical contact for bodies with rounded bases and the inferred drag and added mass coefficients were very close to those from CFD. Some general observations are possible for motion in heave. For the hemispherical base the drag coefficient Cd is very low for small amplitudes but this increases as amplitude is increased. For the rounded base with a flat central area the Cd is larger and for the wholly flat base it is larger again but with values less than 0.35. For a larger geometric scale (times 32) for the hemisphere and round base cases the Cd are generally somewhat reduced. For surge motion the Cd show less variation and are always greater than heave values by at least a factor of 2 which is indicative of effects due to separation and wake generation.

Mass transport in compacted clays is predominantly by diffusion, making them preferred candidates for barriers to radionuclide transport in future repositories for nuclear waste. Diffusivity of species depends on a number of factors: (1) the physical and chemical properties of the clay, such as the geometry and topology of the pore space and the functional groups on the surface; (2) the environmental system, e.g. pH, ionic strength, temperature and organic matter; (3) the nature of species, e.g. charges, sizes and their interactions. Existing models do not consider these characteristics integrally in diffusion simulations and analysis. In this work, a developed pore network model is used to study the diffusion behaviour of Cl- with different ionic strengths. The network is constructed based on experimental pore space information and mineral compositions, and captures the anisotropy and heterogeneity of clays. Opalinus clay is selected for testing the model. The effects of pore size distribution, porosity, cation exchange capacity and surface area on the transport behaviour of anions with different ionic strength are analysed. This improves the understanding of the effects of different factors on the species transport in Opalinus clay. The ionic strength of the pore water is varied between 0.01 and 5 M to evaluate its effect on the diffusion of Cl- in clays. It is shown that the model predictions are in good agreement with measured experimental data of Opalinus clay. The agreement demonstrated, both qualitatively and quantitatively, suggests that the proposed approach for integrating known effects on diffusivity is reliable and efficient.

We propose a mathematical model to represent solid materials with discrete lattices and to analyse their behaviour by calculus on discrete manifolds. Focus is given on the mathematical derivation of the lattice elements by taking into account the stored energy associated with them. We provide a matrix formulation of the nonlinear system describing elasticity with exact kinematics, known as finite strain elasticity in continuum mechanics. This formulation is ready for software implementation and may also be used in atomic scale models as an alternative to existing empirical approach with pair and cohesive potentials. An illustrative example, analysing a local region of a node, is given to demonstrate the model performance. Irish Research Council Science Foundation Ireland Engineering and Physical Sciences Research Council (EPSRC)

Studies of infrastructure have demonstrated broad differences between Northern and Southern cities, and deconstructed urban theory derived from experiences of the networked urban regions of the global North. This includes critiques of the universalization of the historically-culturally produced normative ideal of universal, uniform infrastructure. We introduce the notion of “heterogeneous infrastructure configurations” (HICs) as a way to analyze urban infrastructure that builds on postcolonial critiques of knowledge, as well as ethnographies of everyday Southern urbanisms. We argue that the notion of HIC helps us to move beyond technological and performative accounts of actually existing infrastructures to provide an analytical lens through which to compare different configurations. Our approach enables a clearer analysis of infrastructural artifacts not as individual objects but as parts of geographically spread socio-technological configurations: configurations which might involve many different kinds technologies, relations, capacities and operations, entailing different risks and power relationships. We use examples from ongoing research on sanitation and waste in Kampala, Uganda- a city in which service delivery is characterized by multiplicity, overlap, disruption and inequality- to demonstrate the kinds of research questions that emerge when thinking through the notion of HICs. QC 20171102 Heterogenous Infrastructure Configurations in Uganda Project HICCUP

Jeotgalicoccus sp. 8456 OleTJE (CYP152L1) is a fatty acid decarboxylase cytochrome P450 that uses hydrogen peroxide (H2O2 ) to catalyse production of terminal alkenes, which are industrially important chemicals with biofuel applications. We report enzyme fusion systems in which Streptomyces coelicolor alditol oxidase (AldO) is linked to OleTJE . AldO oxidizes polyols (including glycerol), generating H2O2 as a coproduct and facilitating its use for efficient OleTJE -dependent fatty acid decarboxylation. AldO activity is regulatable by polyol substrate titration, enabling control over H2O2 supply to minimize oxidative inactivation of OleTJE and prolong activity for increased alkene production. We also use these fusion systems to generate novel products from secondary turnover of 2-OH and 3-OH myristic acid primary products, expanding the catalytic repertoire of OleTJE .

Pore network models have been applied widely for simulating a variety of different physical and chemical processes, including phase exchange, non-Newtonian displacement, non-Darcy flow, reactive transport and thermodynamically consistent oil layers. The realism of such modelling, i.e. the credibility of their predictions, depends to a large extent on the quality of the correspondence between the pore space of a given medium and the pore network constructed as its representation. The main experimental techniques for pore space characterisation, including direct imaging, mercury intrusion porosimetry and gas adsorption, are firstly summarised. A review of the main pore network construction techniques is then presented. Particular focus is given on how such constructions are adapted to the data from experimentally characterised pore systems. Current applications of pore network models are considered, with special emphasis on the effects of adsorption, dissolution and precipitation, as well as biomass growth, on transport coefficients. Pore network models are found to be a valuable tool for understanding and predicting meso-scale phenomena, linking single pore processes, where other techniques are more accurate, and the homogenised continuum porous media, used by engineering community.

Bioenergy is given an important role in reaching national and international climate change targets. However, uncertainties relating to emission reductions and the timeframe for these reductions are increasingly recognised as challenges whether bioenergy can deliver the required reductions. This paper discusses and highlights the challenges and the importance of the real greenhouse gas (GHG) reduction potential of bioenergy systems and its relevance for a global 450 ppm CO2e stabilisation target in terms of uncertainties and temporal aspects. The authors aim to raise awareness and emphasise the need for dynamic and consequential approaches for the evaluation of climate change impacts of bioenergy systems to capture the complexity and challenges of their real emission reduction potential within a 2 °C target. This review does not present new research results. This paper shows the variety of challenges and complexity of the problem of achieving real GHG emission reductions from bioenergy systems. By reflecting on current evaluation methods of emissions and impacts from bioenergy systems, this review points out that a rethinking and going beyond static approaches is required, considering each bioenergy systems according to its own characteristics, context and feedbacks. With the development of knowledge and continuously changing systems, policies should be designed in a way that they provide a balance between flexibility to adapt to new information and planning security for investors. These will then allow considering if a bioenergy system will deliver the required emission saving in the appropriate timeframe or not.

Two surface analysis techniques, dual polarization interferometry (DPI) and analysis by an electrochemical quartz crystal microbalance with dissipation capability (E-QCM-D), were paired to find the deposition conditions that give the highest and most stable electrocatalytic activity per adsorbed mass of enzyme. Layers were formed by adsorption from buffered solutions of bilirubin oxidase from Myrothecium verrucaria at pH 6.0 to planar surfaces, under high enzyme loading (≥1 mg mL(-1)) for contact periods of up to 2 min. Both unmodified and carboxylate-functionalized gold-coated sensors showed that a deposition solution concentration of 10-25 mg mL(-1) gave the highest activity per mass of adsorbed enzyme with an effective catalytic rate constant (k(cat)) of about 60 s(-1). The densification of adsorbed layers observed by DPI correlated with reduced bioactivity observed by parallel E-QCM-D measurements. Postadsorption changes in thickness and density observed by DPI were incorporated into Kelvin-Voigt models of the QCM-D response. The modeled response matched experimental observations when the adlayer viscosity tripled after adsorption.

Automatic sentiment analysis provides an effective way to gauge public opinion on any topic of interest. However, most sentiment analysis tools require a general sentiment lexicon to automatically classify sentiments or opinion in a text. One of the challenges presented by using a general sentiment lexicon is that it is insensitive to the domain since the scores assigned to the words are fixed. As a result, while one general sentiment lexicon might perform well in one domain, the same lexicon might perform poorly in another domain. Most sentiment lexica will need to be adjusted to suit the specific domain to which it is applied. In this paper, we present results of sentiment analysis expressed on Twitter by UK energy consumers. We optimised the accuracy of the sentiment analysis results by combining functions from two sentiment lexica. We used the first lexicon to extract the sentiment-bearing terms and negative sentiments since it performed well in detecting these. We then used a second lexicon to classify the rest of the data. Experimental results show that this method improved the accuracy of the results compared to the common practice of using only one lexicon.