1,619 research outputs found

    Spacelab mission dependent training parametric resource requirements study

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    Training flows were developed for typical missions, resource relationships analyzed, and scheduling optimization algorithms defined. Parametric analyses were performed to study the effect of potential changes in mission model, mission complexity and training time required on the resource quantities required to support training of payload or mission specialists. Typical results of these analyses are presented both in graphic and tabular form

    A comparative study of benchmarking approaches for non-domestic buildings: Part 1 ā€“ Top-down approach

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    Benchmarking plays an important role in improving energy efficiency of non-domestic buildings. A review of energy benchmarks that underpin the UKā€™s Display Energy Certificate (DEC) scheme have prompted necessities to explore the benefits and limitations of using various methods to derive energy benchmarks. The existing methods were reviewed and grouped into top-down and bottom-up approaches based on the granularity of the data used. In the study, two top-down methods, descriptive statistics and artificial neural networks (ANN), were explored for the purpose of benchmarking energy performances of schools. The results were used to understand the benefits of using these benchmarks for assessing energy efficiency of buildings and the limitations that affect the robustness of the derived benchmarks. Compared to the bottom-up approach, top-down approaches were found to be beneficial in gaining insight into how peers perform. The relative rather than absolute feedback on energy efficiency meant that peer pressure was a motivator for improvement. On the other hand, there were limitations with regard to the extent to which the energy efficiency of a building could be accurately assessed using the top-down benchmarks. Moreover, difficulties in acquiring adequate data were identified as a key limitation to using the top-down approach for benchmarking non-domestic buildings. The study suggested that there are benefits in rolling out of DECs to private sector buildings and that there is a need to explore more complex methods to provide more accurate indication of energy efficiency in non-domestic buildings

    Density and morphology: from the building scale to the city scale

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    The density of the domestic building stock of London is explored, moving from the scale of individual house and blocks of flats, through larger geographical units, to complete boroughs. The description of the stock is highly detailed and is made using the 3DStock method, which derives building geometry from digital maps and LiDAR (laser measurements from overflying aircraft). This means that accurate estimates of floor areas can be made and used to measure densities as Floor Space Index (FSI) values. Ground coverage or Ground Space Index (GSI) values are calculated from building footprints and land boundaries. The Spacemate tool, devised by Berghauser Pont and Haupt, is used to plot the types and ages of dwellings in terms of FSI, GSI and numbers of storeys. Figures for actual annual gas and electricity consumption are attached to each dwelling. Analysis shows that, in general, energy-use intensitiesā€”and especially the intensity of gas use for heatingā€”decrease with increasing density, and with the transition between house types, from detached, to semi-detached, to terraces, to (low-rise) flats

    Magnetoelectric domains and their switching mechanism in a Y-type hexaferrite

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    By employing resonant X-ray microdiffraction, we image the magnetisation and magnetic polarity domains of the Y-type hexaferrite Ba0.5_{0.5}Sr1.5_{1.5}Mg2_2Fe12_{12}O22_{22}. We show that the magnetic polarity domain structure can be controlled by both magnetic and electric fields, and that full inversion of these domains can be achieved simply by reversal of an applied magnetic field in the absence of an electric field bias. Furthermore, we demonstrate that the diffraction intensity measured in different X-ray polarisation channels cannot be reproduced by the accepted model for the polar magnetic structure, known as the 2-fan transverse conical (TC) model. We propose a modification to this model, which achieves good quantitative agreement with all of our data. We show that the deviations from the TC model are large, and may be the result of an internal magnetic chirality, most likely inherited from the parent helical (non-polar) phase.Comment: 9 figure

    Novel routes towards antibiotics using organocatalytic and biocatalytic approaches

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    Aromatic ketodiols and 2-amino-1,3-diols are present in many interesting biologically-active molecules. The aminodiol motif itself is present in the broad-spectrum antibiotics chloramphenicol and thiamphenicol. This thesis describes organocatalytic and biocatalytic approaches to this family of compounds, using organocatalysts and transketolase and transaminase enzymes. Transketolase (TK) is a ThDP-dependent enzyme which has been used to prepare aliphatic ketodiols with good yields and high degrees of stereoselectivity. A biomimetic approach to racemic ketodiols has also been reported. Transaminases (TAms) are a broad family of enzymes which stereoselectively form amines from ketone or aldehyde functionalities. A two-step TK/TAm pathway has already been reported which gives access to aliphatic aminodiols, but the preparation of aromatic aminodiols using this combined TK/TAm strategy has yet to be investigated. A literature review of transketolase, transaminase and biocatalysis in general is presented in chapter 1. The substrate scope of the biomimetic TK reaction to prepare racemic aromatic ketodiols has been investigated, and an asymmetric variant developed which was used to transform aromatic aldehydes in water in up to 50% ee (chapter 2). A range of single TK mutants have been used to transform a small range of basic aromatic aldehydes (chapter 3) with low yields but good stereoselectivities (up to 80% ee). In order to create more active combination mutant TKs, a range of mutants were made and tested with aliphatic aldehdyes (chapter 4) to determine what combinations of single mutants could be created without sacrificing enzyme structure and function. With knowledge gained from this and by further study of the TK active-site, a range of combination mutants were then created which accepted a range of functionalised benzaldehydes with excellent yields and stereoselectivities (95% ee). Possible future work is outlined in chapter 7

    Improved benchmarking comparability for energy consumption in schools

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    The method behind the UK Display Energy Certificate (DEC) improves the comparability of benchmarking by accounting for variations in weather and occupancy. To improve the comparability further, the incorporation of other features that are intrinsic to buildings (e.g. built form and building services) deserve exploration. This study investigates the impact of these features and explores ways to improve further comparability in benchmarking the energy performance of schools. Statistical analyses of approximately 7700 schools were performed, followed by analyses of causal factors in 465 schools in greater detail using artificial neural networks (ANNs), each designed to understand and identify the factors that have significant impact on the pattern of energy use of schools. Changes in the pattern of energy use of schools have occurred over the past four years. This fact highlights issues associated with static benchmarks. A significant difference in energy performance between primary and secondary schools meant that it was necessary to re-examine the way non-domestic buildings are classified. Factors were identified as having significant impact on the pattern of energy use. The characteristics raise new possibilities for developing sector-specific methods and improving comparability

    CO2 storage risk minimization through systematic identification and assessment of faults: a Williston Basin case study

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    AbstractThe Williston Basin is considered a tectonically stable area with only a few major inactive faults. Over the last 50 years, extensive hydrocarbon exploration in the basin has demonstrated that smaller faults do exist and closer evaluation is necessary to determine the nature of this faulting. An area near the town of Dickinson, North Dakota, has been identified as a potential location for CO2 storage/enhanced oil recovery. A thorough geologic assessment of the area has identified structural anomalies that may indicate the presence of faulting, which, in turn, may affect precise CO2 storage site selection

    Scaling and allometry in the building geometries of Greater London

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    Many aggregate distributions of urban activities such as city sizes reveal scaling but hardly any work exists on the properties of spatial distributions within individual cities, notwithstanding considerable knowledge about their fractal structure. We redress this here by examining scaling relationships in a world city using data on the geometric properties of individual buildings. We first summarise how power laws can be used to approximate the size distributions of buildings, in analogy to city-size distributions which have been widely studied as rank-size and lognormal distributions following Zipf and Gibrat. We then extend this analysis to allometric relationships between buildings in terms of their different geometric size properties. We present some preliminary analysis of building heights from the Emporis database which suggests very strong scaling in world cities. The data base for Greater London is then introduced from which we extract 3.6 million buildings whose scaling properties we explore. We examine key allometric relationships between these different properties illustrating how building shape changes according to size, and we extend this analysis to the classification of buildings according to land use types. We conclude with an analysis of two-point correlation functions of building geometries which supports our non-spatial analysis of scaling.Comment: 28 pages, 8 figure
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