Mott MacDonald

About: Mott MacDonald is a company organization based out in London, United Kingdom. It is known for research contribution in the topics: Electric power system & Wind power. The organization has 586 authors who have published 529 publications receiving 9801 citations. The organization is also known as: Mott MacDonald Group & MMD.

Start, development and status of the regulator-led national groundwater resources modelling programme in England and Wales

Abstract: Abstract Over the last 10 years there has been a unique regulator-led programme involving extensive development of regional groundwater models across England and Wales for water resources purposes by the Environment Agency for England and Wales. Eight regionally managed programmes are underpinned by a framework, which has allowed a coordinated national approach. The main uses of the models are for catchment abstraction management and licensing. Models have also assisted in monitoring network design, investigating groundwater quality and implementing groundwater source protection zones. A five-yearly review of the programmes recognized the importance of benefit realization and stakeholder involvement as well as technical good practice. The programme already delivered provides a solid foundation for supporting the management decisions required in areas such as climate change mitigation and integrated catchment management using appropriate tools at a time of rapid organization change and financial uncertainty.

Why Use One Model? An Approach for Encompassing Model Uncertainty and Improving Best Practice

Abstract: There has been some discussion within the UK modelling community regarding the preferred choice of dispersion model for assessing the air quality impact of elevated point sources, each of which is reported to perform better than the other in certain circumstances. Coupled to this is the growing acceptance within the modelling community to include some recognition of model uncertainty in its reporting. As computer processing speeds increase further, this paper considers the possibility of using more than one model and highlights some of the advantages in doing so.

Inter-segment complementarity in orbiviruses: a driver for co-ordinated genome packaging in the Reoviridae?

Abstract: The process by which eukaryotic viruses with segmented genomes select a complete set of genome segments for packaging into progeny virus particles is not understood. In this study a model based on the association of genome segments through specific RNA–RNA interactions driven by base pairing was formalized and tested in the Orbivirus genus of the Reoviridae family. A strategy combining screening of the genomic sequences for inter-segment complementarity with direct functional testing of inter-segment RNA–RNA interactions using reverse genetics is described in the type species of the Orbivirus genus, Bluetongue virus (BTV). Two examples, involving four of the ten BTV genomic segments, of specific inter-segment interaction motifs whose maintenance is essential for the generation of infectious virus, were identified. Equivalent inter-segment complementarities were found between the identified regions of the orthologous genome segments of all orbiviruses, including phylogenetically distant species. Specific interaction of the participating RNA segments was confirmed in vitro using electrophoretic mobility shift assays, with the interactions inhibited using oligonucleotides complementary to the interaction motif of one of the interacting partners, and also through mutagenesis of the motifs. In each example, the base pairing rather than the absolute sequence was critical to the formation of a functional inter-segment interaction, with mutations only being tolerated in rescued virus if compensating changes were made in the interacting partner to restore uninterrupted base pairing. The absolute sequence of the complementarity motifs varied between species, indicating that this newly identified phenomenon may contribute to the observed lack of reassortment between Orbivirus species.

Axial compression tests on elliptical high strength steel tubes filled with self-compacting concrete of different mix proportions

Abstract: The compaction state and the paste volume of concrete may significantly influence the compressive behaviour of concrete-filled steel tube (CFST) columns, while limited studies have been conducted to understand the compressive behaviour of CFST columns with different mix proportions. This study presents an experimental investigation to the axial compressive behaviour of elliptical CFST (ECFST) column consisting of a high-strength steel (HSS) tube and a self-compacting concrete (SCC) core with different mix proportions. Eighteen ECFST column specimens, fabricated with high-strength elliptical steel tubes in three different cross-sections and three batches of concrete with different mix proportions, were tested under axial compression . The parameters under investigation are the concrete paste volumes (41%, 37% and 32.5%), the cross-sectional aspect ratios (1, 1.5 and 2) and the compaction conditions (with and without mechanical compaction). The standard cylinder tests reveal that SCC without mechanical compaction has a better filling ability and thus a better self-compaction capability when the paste volume is larger than 37%, while SCC with mechanical compaction has the highest strength when the paste volume is the lowest. The axial compression tests show that the peak axial load capacities of ECFST columns are dependent on the paste and aggregate contents in concrete. The compaction state also affects the performance ECFST columns because compaction usually increases concrete strength especially when the aggregate content is high. In addition, it is found that key performance parameters (e.g., strain enhancement ratio, ductility and strength index) all decrease with the increase of cross-sectional aspect ratio due to the non-uniform confinement provided by elliptical steel tubes.