5,201 research outputs found

    The Role of Futureproofing in the Management of Infrastructural Assets

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    Ensuring long-term value from infrastructure is essential for a sustainable economy. In this context, futureproofing involves addressing two broad issues: i. Ensuring the ability of infrastructure to be resilient to unexpected or uncontrollable events e.g. extreme weather events; and ii. Ensuring the ability to adapt to required changes in structure and / or operations of the infrastructure in the future e.g. expansion of capacity, change in usage mode or volumes. Increasingly, in their respective roles, infrastructure designers/builders and owners/operators are being required to develop strategies for futureproofing as part of the life cycle planning for key assets and systems that make up infrastructure. In this paper, we report on a preliminary set of studies aimed at exploring the following issues related to infrastructure / infrastructure systems: • What is intended by the futureproofing of infrastructural assets? • Why and when to futureproof critical infrastructure? • How can infrastructure assets and systems be prepared for uncertain futures? • How can futureproofing be incorporated into asset management practice? In order to seek answers to the above questions, the Cambridge Centre for Smart Infrastructure and Construction (CSIC) has conducted two industrial workshops bringing together leading practitioners in the UK infrastructure and construction sectors, along with government policy makers. This paper provides an initial summary of the findings from the workshops (part presentation, part working sessions), and proposes a simple framework for linking futureproofing into broader asset management considerations. To begin, an overview of futureproofing and motivate the need for futureproofing infrastructure assets is provided. Following this, an approach to futureproofing infrastructure portfolios is presented that organisations in the infrastructure sector can use. Key barriers to futureproofing are also presented before examining the ISO 55001 asset management standard to highlight the interplay between futureproofing and infrastructural asset management. Finally, different ways by which an effective futureproofing strategy can enhance the value of infrastructure are examined

    Coulomb interactions in single, charged self-assembled quantum dots: radiative lifetime and recombination energy

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    We present results on the charge dependence of the radiative recombination lifetime, Tau, and the emission energy of excitons confined to single self-assembled InGaAs quantum dots. There are significant dot-to-dot fluctuations in the lifetimes for a particular emission energy. To reach general conclusions, we present the statistical behavior by analyzing data recorded on a large number of individual quantum dots. Exciton charge is controlled with extremely high fidelity through an n-type field effect structure, providing access to the neutral exciton (X0), the biexciton (2X0) and the positively (X1+) and negatively (X1-) charged excitons. We find significant differences in the recombination lifetime of each exciton such that, on average, Tau(X1-) / Tau(X0) = 1.25, Tau(X1+) / Tau(X0) = 1.58 and Tau(2X0) / Tau(X0) = 0.65. We attribute the change in lifetime to significant changes in the single particle hole wave function on charging the dot, an effect more pronounced on charging X0 with a single hole than with a single electron. We verify this interpretation by recasting the experimental data on exciton energies in terms of Coulomb energies. We show directly that the electron-hole Coulomb energy is charge dependent, reducing in value by 5-10% in the presence of an additional electron, and that the electron-electron and hole-hole Coulomb energies are almost equal.Comment: 8 pages, 7 figures, submitted to Phys. Rev.

    Salinity and waterlogging on the Esperance Downs Research Station

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    Details the situation on the station so that the demonstration and research programs can be designed and the effect of the treatments assessed. Past work on the station has been briefly summarised and the results of geophysical surveys and additional drilling are given. Surveys of electromagnetic terrain conductivities have shown where salinity is most serious at present. The most deeply penetrating method may have identified areas likely to developing salinity in future

    Long-term carbon and nitrogen dynamics at SPRUCE revealed through stable isotopes in peat profiles

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    Peatlands encode information about past vegetation dynamics, climate, and microbial processes. Here, we used δ15N and δ13C patterns from 16 peat profiles to deduce how the biogeochemistry of the Marcell S1 forested bog in northern Minnesota responded to environmental and vegetation change over the past  ∼ 10000 years. In multiple regression analyses, δ15N and δ13C correlated strongly with depth, plot location, C∕N, %N, and each other. Correlations with %N, %C, C∕N, and the other isotope accounted for 80% of variance for δ15N and 38% of variance for δ13C, reflecting N and C losses. In contrast, correlations with depth and topography (hummock or hollow) reflected peatland successional history and climate. Higher δ15N in plots closer to uplands may reflect upland-derived DON inputs and accompanying shifts in N dynamics in the lagg drainage area surrounding the bog. The Suess effect (declining δ13CO2 since the Industrial Revolution) lowered δ13C in recent surficial samples. High δ15N from −35 to −55cm probably indicated the depth of ectomycorrhizal activity after tree colonization of the peatland over the last 400 years, as confirmed by the occasional presence of wood down to −35cm depth. High δ13C at  ∼ 4000 years BP (−65 to −105cm) could reflect a transition at that time to slower rates of peat accumulation, when 13C discrimination during peat decomposition may increase in importance. Low δ13C and high δ15N at −213 and −225cm ( ∼ 8500 years BP) corresponded to a warm period during a sedge-dominated rich fen stage. The above processes appear to be the primary drivers of the observed isotopic patterns, whereas there was no clear evidence for methane dynamics influencing δ13C patterns

    Effects of waterlogging on crop and pasture production in the Upper Great Southern, Western Australia

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    Separate estimates of the effect of waterlogging on cereal yields were made using rainfall and crop yield statistics, and remote sensing. Both methods showed that waterlogging costs tens of millions of dollars each year in lost crop production in the Upper Great Southern Statistical Division. The costs will be over $100 m in wet years. Losses in pasture production are likely to be of a similar magnitude, but are harder to quantify

    Ready configuration of machines into an existing manufacturing system

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    This paper focuses on simplifying and easing the integration of a new machine into an existing conventional hierarchical manufacturing system. Based on a distributed manufacturing paradigm, it proposes the functions and interfaces that a new machine and an existing manufacturing system should possess so that ready and simple configuration of additional machines can be achieved. The configuration process is intended to include, not only mechanical and electrical interfaces, but also decision system interfaces (such as planning, scheduling, and shop-floor control). Preliminary laboratory experiments to compare the reconfigurability resulting from a conventional integration method and the proposed distributed method are presented and discussed. © 2007 ISAM

    The divergence of theoretical and actual designs in a holonic packing cell

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    The aim of this paper is to take the reader through the decisions made in designing a holonic system architecture to support customised packing of gift boxes with personal grooming (Gillette) products. The paper highlights issues that cause a divergence between a theoretical model of a holonic system and the approach that was actually encoded

    Investigation of a saline valley on Allandale Research Farm

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    Geophysical surveys and drilling were used to investigate a saline valley on Allandale Research Farm. These techniques showed that the geology is controlling the location of two main areas of saline seeps and they identified another area at risk of increased salinity. They were also used to obtain information on the groundwater system and to assist in making management recommendations. Electromagnetic terrain conductivity surveys showed that the most saline soils occurred upstream of a cross-cutting magnetic anomaly caused by a dolerite dyke. A seismic survey showed that the anomaly coincided with a bedrock rise. This bedrock rise restricts groundwater flow through the catchment and forces saline groundwater to the surface where it evaporates causing salts to build up in the soil profile. A second area of saline surface soils occurs further downstream. Outcrops of granite in the creek indicate that another bedrock rise is the cause for the location of this seep. A third area in the valley upslope from the main saline area has a high subsoil conductivity and is immediately upslope of a second magnetic anomaly. This area may become more saline in the future. Drilling confirmed the seismic profile near the dolerite dyke in the main saline area. It also indicated that deep groundwater pressures are above ground level along the whole of the valley/ becoming higher with increased distance downstream. The quality of the groundwater ranged from 3,500 to 6,500 mg.Cl-1/L. Three recommendations are made for the area: (i) the construction of an interceptor drain/ upslope of each saline area, to reduce waterlogging; (ii) fencing the saline areas, and revegetating to salt tolerant grasses, bushes and trees; (iii) limiting recharge on coarse textured soils in the catchment above the valley by growing crops and/or trees with high evapotranspiration potentials
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