Generic approach for deriving reliability and maintenance requirements through consideration of in-context customer objectives

Not all implementations of reliability are equally effective at providing customer and user benefit. Random system failure with no prior warning or failure accommodation will have an immediate, usually adverse impact on operation. Nevertheless, this approach to reliability, implicit in measurements such as ‘failure rate’ and ‘MTBF’, is widely assumed without consideration of potential benefits of pro-active maintenance. Similarly, it is easy to assume that improved maintainability is always a good thing. However, maintainability is only one option available to reduce cost of ownership and reduce the impact of failure. This paper discusses a process for deriving optimised reliability and maintenance requirements through consideration of in-context customer objectives rather than a product in isolation

A set-based approach for coordination of multi-level collaborative design studies

Presented in this paper is a framework for design coordination of hierarchical (multi-level) design studies. The proposed framework utilizes margin management and set-based design principles for handling the challenges associated with vertical and horizontal design coordination. The former is based on flexible constraints/margins, while the latter is handled by intersecting feasible design spaces across different teams. The framework is demonstrated with an industrial test-case from the UK ATI APPROCONE (Advanced PROduct CONcept analysis Environment) project

Stronger diversity effects with increased environmental stress : a study of multitrophic interactions between oak, powdery mildew and ladybirds

Recent research has suggested that increasing neighbourhood tree species diversity may mitigate the impact of pests or pathogens by supporting the activities of their natural enemies and/or reducing the density of available hosts. In this study, we attempted to assess these mechanisms in a multitrophic study system of young oak (Quercus), oak powdery mildew (PM, caused by Erysiphe spp.) and a mycophagous ladybird (Psyllobora vigintiduo-punctata). We assessed ladybird mycophagy on oak PM in function of different neighbourhood tree species compositions. We also evaluated whether these species interactions were modulated by environmental conditions as suggested by the Stress Gradient Hypothesis. We adopted a complementary approach of a field experiment where we monitored oak saplings subjected to a reduced rainfall gradient in a young planted forest consisting of different tree species mixtures, as well as a lab experiment where we independently evaluated the effect of different watering treatments on PM infections and ladybird mycophagy. In the field experiment, we found effects of neighbourhood tree species richness on ladybird mycophagy becoming more positive as the target trees received less water. This effect was only found as weather conditions grew drier. In the lab experiment, we found a preference of ladybirds to graze on infected leaves from trees that received less water. We discuss potential mechanisms that might explain this preference, such as emissions of volatile leaf chemicals. Our results are in line with the expectations of the Natural Enemies Hypothesis and support the hypothesis that biodiversity effects become stronger with increased environmental stress

A method for 3D printing bio-cemented spatial structures using sand and urease active calcium carbonate powder

The substitution of Portland cement with microbially based bio-cement for the production of construction materials is an emerging sustainable technology. Bio-cemented building components such as bricks have been fabricated in molds, where bacteria-containing aggregates solidify when treated with a cementation solution. Thisrestricts component size due to the limitedfluid penetration depth and narrows options for component customization. The use of additive manufacturing technologies has the potential to overcome those limitations and toexpand the range of bio-cement applications. In the present work an automated process for the production ofspatial structures has been developed, in which sand and urease active calcium carbonate powder were selectively deposited within a print volumeand treatedwith a cementation solution.This method provided conditionsfor calcite precipitation in the powder-containing areas, whereas areas of pure sand served as removable supportstructure allowing improvedfluid exchange. The 3D printed structure was geometrically stable and had sharplydefined boundaries. Compressive strength tests on cylindricalspecimens showed thatthe used powder-sandmixwas suitable for the production of high-strength bio-cemented material. The present work demonstrates an application of bio-cement in an additive manufacturing process, that can potentially be used to produce resourceefficient sustainable building components

Efficient use of water for irrigation in the upper midwest

The objectives of this multidisciplinary interinstitutional regional study on the efficient use of water for irrigation in the upper Midwest were: (1) to determine parameters needed for existing or improved models of crop response; (2) to relate yield response to costs and revenues by assessing the water demand for irrigation; and (3) to study the demand for irrigation, present and projected, and its availability as related to public allocation decisions. From this series of studies it was concluded that: (1) There are many areas of the Midwest with sufficient groundwater and surface water resources to support the development of irrigation. (2) Soil moisture models indicate that only moderate yield response to irrigation can be expected on high moisture soils; on lighter soils and claypan soils, yield response is significant, even in regions with relatively high precipitation. (3) Irrigation and drainage on claypan soils can dramatically increase corn yields. (4) It appears economically worthwhile for the individual farmer operating on moderate soils or on claypan soils to evaluate capital investments in irrigation along with other capital investments. (5) Increases in yields and persistence of alfalfa due to irrigation appear to be insignificant when compared to conventional management practices; further research is needed. A potential, however, appears to exist for improving adaptation of a1 fa1 fa varieties to soil water deficits.U.S. Geological SurveyU.S. Department of the InteriorOpe

The performance of FLake in the Met Office Unified Model

We present results from the coupling of FLake to the Met Office Unified Model (MetUM). The coupling and initialisation are first described, and the results of testing the coupled model in local and global model configurations are presented. These show that FLake has a small statistical impact on screen temperature, but has the potential to modify the weather in the vicinity of areas of significant inland water. Examination of FLake lake ice has revealed that the behaviour of lakes in the coupled model is unrealistic in some areas of significant sub-grid orography. Tests of various modifications to ameliorate this behaviour are presented. The results indicate which of the possible model changes best improve the annual cycle of lake ice. As FLake has been developed and tuned entirely outside the Unified Model system, these results can be interpreted as a useful objective measure of the performance of the Unified Model in terms of its near-surface characteristics

International Delegations and the Values of Federalism

Inland water sediments receive large quantities of terrestrial organic matter(1-5) and are globally important sites for organic carbon preservation(5,6). Sediment organic matter mineralization is positively related to temperature across a wide range of high-latitude ecosystems(6-10), but the situation in the tropics remains unclear. Here we assessed temperature effects on the biological production of CO2 and CH4 in anaerobic sediments of tropical lakes in the Amazon and boreal lakes in Sweden. On the basis of conservative regional warming projections until 2100 (ref. 11), we estimate that sediment CO2 and CH4 production will increase 9-61% above present rates. Combining the CO2 and CH4 as CO2 equivalents (CO(2)eq; ref. 11), the predicted increase is 2.4-4.5 times higher in tropical than boreal sediments. Although the estimated lake area in low latitudes is 3.2 times smaller than that of the boreal zone, we estimate that the increase in gas production from tropical lake sediments would be on average 2.4 times higher for CO2 and 2.8 times higher for CH4. The exponential temperature response of organic matter mineralization, coupled with higher increases in the proportion of CH4 relative to CO2 on warming, suggests that the production of greenhouse gases in tropical sediments will increase substantially. This represents a potential large-scale positive feedback to climate change

Primary Pneumocystis Infection in Infants Hospitalized with Acute Respiratory Tract Infection

Primary P. jirovecii infection may appear as a self-limiting upper respiratory tract infection in infants