Modelling of Dynamic Crack Propagation in 3D Elastic Continuum Using Configurational Mechanics

This paper presents the theoretical basis and numerical implementation for simulating dynamic crack propagation in 3D hyperelastic contina within the context of configurational mechanics. The approach taken is based on the principle of global maximum energy dissipation for elastic solids, with configurational forces determining the direction of crack propagation. The work builds on the developments made by the authors for static analysis [1], incorporating the influence of the kinetic energy. The nonlinear system of equations are solved in a monolithic manner using Newton-Raphson scheme. Initial numerical results are presented

The Accuracy of Subhalo Detection

With the ever increasing resolution of N-body simulations, accurate subhalo detection is becoming essential in the study of the formation of structure, the production of merger trees and the seeding of semi-analytic models. To investigate the state of halo finders, we compare two different approaches to detecting subhaloes; the first based on overdensities in a halo and the second being adaptive mesh refinement. A set of stable mock NFW dark matter haloes were produced and a subhalo was placed at different radii within a larger halo. SUBFIND (a Friends-of-Friends based finder) and AHF (an adaptive mesh based finder) were employed to recover the subhalo. As expected, we found that the mass of the subhalo recovered by SUBFIND has a strong dependence on the radial position and that neither halo finder can accurately recover the subhalo when it is very near the centre of the halo. This radial dependence is shown to be related to the subhalo being truncated by the background density of the halo and originates due to the subhalo being defined as an overdensity. If the subhalo size is instead determined using the peak of the circular velocity profile, a much more stable value is recovered. The downside to this is that the maximum circular velocity is a poor measure of stripping and is affected by resolution. For future halo finders to recover all the particles in a subhalo, a search of phase space will need to be introduced.Comment: 9 pages, 7 figures, accepted for publication in MNRA

Archaeological trench evaluation and resistivity survey at Membury Court, Membury, East Devon

This report has been prepared for Devon County Council and presents the results of an archaeological trench evaluation and targeted electrical resistance survey (resistivity) of land at Membury Court, Membury, East Devon (Figure 1; ST 26364 03803). The investigation was commissioned by Devon County Council and was carried out in accordance with a Brief issued by Cressida Whitton, Archaeologist, Devon County Council Historic Environment Service (DCCHES Ref. Arch/AE/ED/17777). The purpose of the trench evaluation and resistivity survey was to further characterise the form, nature and depth of any sub-surface archaeological remains indicated by a previous magnetometer survey (Smart 2010), in order to inform appropriate decision and management in response to proposed harrowing and re-seeding of the land

Perceived environmental factors associated with obesity in Libyan men and women

Background: There is a lack of research pertaining to the links between built environment attributes and obesity in adults in the Eastern Mediterranean Region. In the Libyan context, no previous studies have been conducted to investigate this relationship. Therefore, the aim of this study was to examine associations between perceived neighbourhood built environmental attributes and obesity among Libyan men and women. The prevalence of overweight and obesity was also assessed. Methods: A cross-sectional study design was used for the population-based survey in Benghazi, Libya. A multi-stage cluster sampling technique was used to select Libyan adults from the Benghazi electoral register. The Physical Activity Neighbourhood Environment Scale (PANES) was used to measure participants’ perception of neighbourhood environmental factors. Using the Tanita BC-601 Segmental Body Composition Monitor and a portable stadiometer, anthropometric measurements were taken at a mutually agreeable place by qualified nurses. Results: Four hundred and one Libyan adults were recruited (78% response rate). Participants were aged 20–65 years, 63% were female, and all had lived in Benghazi for over 10 years. The prevalence of obesity and overweight was 42.4% and 32.9% respectively. A significant association was found between BMI and 6 neighbourhood environment attributes, specifically: street connectivity, unsafe environment and committing crimes at night, and neighbourhood aesthetics. For men only, these were: access to public transport, access to recreational facilities, and unsafe environment and committing crimes during the day. The attribute ‘residential density zones’ was only significant for women. Conclusions: The study suggests that Libyan people are at risk of living in neighbourhoods with unsupportive environmental features of physical activity, which are likely to promote obesity of both genders. The findings of this study could inform Libyan health policies about interventions in the obesogenic environments that might slow the obesity epidemic and contain the public health crisis. This study suggests that further research is needed, within the Libyan context, to explore the impact of the neighbourhood environment attributes on contributing to increased obesity

Commercial development of bio-combustible fuels from hydrothermal liquefaction of waste using solar collectors

Current methods to improve the viability of microalgae based biofuel production depend on improved microalgae strains, biorefinery concepts and identification of higher value applications such as cosmetics and nutraceuticals. Despite such efforts, the energy inputs into the microalgae conversion process remain high. The technical approach presented is to design, deploy and field test an integrated set-up of Concentrated Solar Power and Hydrothermal Liquefaction systems to produce bio-oil and evaluate the production and conversion processes. Phycofeeds’ approach is to integrate CSP and HTL technologies into the conversion process to improve the energy efficiency and the economic case for scaling microalgae based biofuel production. Further sustainability enhancements are achieved by integrating wastewater feedstock and market integration of output by-products for the aquaculture feed industry. This paper presents the microalgae harvesting and HTL bio-oil formation analysis procedures on a pre-pilot field scale. Solar concentrating captors are described and theoretical values obtained prior to experimental work that will be carried out in India

A disruptive alternative to semi-continuous multi-column chromatography processes

Protein purification to date is still dominated by expensive chromatography operations. Within the bioprocessing segment of the biopharmaceutical industry, enormous advances in upstream processing performance have moved the cost-reduction bottleneck to downstream processing (DSP). In an effort to reduce DSP costs, the industry is progressively turning to multi-column semi-continuous manufacturing techniques, adapted from neighbouring chemical processing industries. In the case of Affinity Chromatography, the primary theoretical advantage lies in alleviating particularly expensive bind/elute capture steps by allowing saturation of any given unit of resin with product feed while routing the partially depleted effluent flow-through material to follow-on unsaturated resin through the use of multiple columns in a sequence. The saturation better utilises the resin in each of its cycles allowing a reduction in per gram cost and improved time usage, and since saturation can achieve the full static binding capacity without being limited by a dynamic flow, this allows the system to flow faster, saving even more time. However, industrial adoption of these new techniques has been slow, owing to their significant increase in developmental and operational complexity and the capital expense of additional hardware requirements. In this presentation we will reveal and discuss processing factors that may significantly impact the true benefits in speed for multi-column processes, particularly relating to the necessary scheduling effects of aligning multiple synchronous columns, and to back pressure and column height effects that both slow the achievable productivity and mask true comparisons with traditional batch chromatography. We have found scenarios where these factors can combine to make semi-continuous multi-column processes significantly slower than equivalent batch processes, and the loss in productivity can, in some circumstances, cancel much of the cost savings on resin consumption. In an effort to understand, improve and simplify these semi-continuous processes, we internally developed a novel and potentially disruptive operational method that matches or exceeds the benefits of a semi-continuous process, without the complexity. Data from a prototype un-optimised version tested at pilot scale will show that significant performance gains can be achieved on standard chromatography equipment with minimal modification