254,566 research outputs found

    Rapid growth and concerted sexual transitions by a bloom of the harmful dinoflagellate Alexandrium fundyense (Dinophyceae)

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    © The Author(s), 2015. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Limnology and Oceanography 60 (2015): 2059–2078, doi:10.1002/lno.10155.Transitions between life cycle stages by the harmful dinoflagellate Alexandrium fundyense are critical for the initiation and termination of its blooms. To quantify these transitions in a single population, an Imaging FlowCytobot (IFCB), was deployed in Salt Pond (Eastham, Massachusetts), a small, tidally flushed kettle pond that hosts near annual, localized A. fundyense blooms. Machine-based image classifiers differentiating A. fundyense life cycle stages were developed and results were compared to manually corrected IFCB samples, manual microscopy-based estimates of A. fundyense abundance, previously published data describing prevalence of the parasite Amoebophrya, and a continuous culture of A. fundyense infected with Amoebophrya. In Salt Pond, a development phase of sustained vegetative division lasted approximately 3 weeks and was followed by a rapid and near complete conversion to small, gamete cells. The gametic period (∼3 d) coincided with a spike in the frequency of fusing gametes (up to 5% of A. fundyense images) and was followed by a zygotic phase (∼4 d) during which cell sizes returned to their normal range but cell division and diel vertical migration ceased. Cell division during bloom development was strongly phased, enabling estimation of daily rates of division, which were more than twice those predicted from batch cultures grown at similar temperatures in replete medium. Data from the Salt Pond deployment provide the first continuous record of an A. fundyense population through its complete bloom cycle and demonstrate growth and sexual induction rates much higher than are typically observed in culture.National Science Foundation Grant Number: OCE-0430724, OCE-0911031, and OCE-1314642; National Institutes of Health Grant Number: NIEHS-1P50-ES021923-01; National Park Service (NPS) Cooperative Agreement Grant Number: H238015504; Gordon and Betty Moore Foundation Grant Number: #2649 to HMS; IOF Grant Number: MOHAB PIOF-GA-25226

    Development of a whole life cycle cost model for electrification options on the UK rail system

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    Projects to deliver Overhead Line Equipment (OLE) electrification on the UK rail infrastructure system presents technical challenges which the rail industry in Britain have not traditionally had to consider. Whole Life Cycle assessment provides decision makers with cost estimates for the installation phase and over the entire service life of the system, including disposal. The OLE projects face a particular problem when analysing the best option for overbridges. Much of the rail infrastructure has not traditionally had to consider overhead clearances and therefore many of the bridges are only a little taller than the rolling stock. In addition to the difficulties in assessing the Life-Cycle costs of assets that have historically been used in very limited scales, the Whole Life Cycle assessment must consider the various engineering options that are available for projects. The three competing options (bridge rebuild, track lowering, reduced clearance) are all going to have very different capital expenditure (CAPEX) and operating expenditure (OPEX) costs. This work presents a model created to predict these costs over the anticipated assessment period. The developed model predicts capital expenditures, maintenance and service disruption costs and links them to the three major assets options involved in OLE underbridges

    Enhancing service requirements of technical product-service systems

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    Due to the integration of product and services as a new business model, product reliability and strategies for cost reduction at the early design stage have become important factors for many manufacturing firms. It is, therefore, critical at this phase to analyse the risk involved with Service Requirements noncompliance in order to help designers make informed decisions; as these decisions have a large impact on the Product Life Cycle (PLC). An investigation has been performed into how Service Requirements are analysed in a service orientated business to achieve reduced Life Cycle Cost (LCC) and improvements of existing Service Requirements. Weibull distribution and Monte Carlo principle have been proposed to do so; as they are considered as the most widely used in product reliability studies in the industry sector. A generic methodology for risk evaluation of failure to deliver a new product against Service Requirements is presented in this paper. This is part of the ongoing research project which aims to, apart from comparing current and targeted Service Requirements, it also facilitates an optimisation of them at the minimum risk of nonconformity

    Uncertainty of net present value calculations and the impact on applying integrated maintenance approaches to the UK rail industry

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    The Public performance indicator (PPI) is an important Key Performance Indicator for Network Rail and monitored carefully by the organisation and their external stakeholders. Condition monitoring is of increasing interest within network rail as a suitable method for increasing asset reliability and improving the PPI metric. As condition monitoring methods are identified each will need assessment to establish the cost and benefit. Benefit can be measured in cost savings as poor PPI performance results in fines. Within many industries Net Present Value (NPV) calculations are used to determine how quickly investments will break-even. Cost-risk is a term that is used to describe the financial impact of an unexpected event (a risk). This paper outlines a more detailed approach to calculating NPV which considers the cost-risk effect of changes of the denial of service charging rate. NPV prediction is of importance when assessing when to deploy different fault detection strategies to maintenance issues, and therefore the cost-risk of the NPV calculation should be used to support asset management decisions

    An integrated aerospace requirement setting and risk analysis tool for life cycle cost reduction and system design improvement

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    In the early conceptual stage of the service orientated model, decisions regarding the design of a new technical product are largely influenced by Service Requirements. Those decisions, therefore, have to merge both technical and business aspects to obtain desired product reliability and reduced Whole Life Cost (WLC). It is, therefore, critical at that phase to define the risk of potential noncompliance of Service Requirements in order to ensure the right design choices; as these decisions have a large impact on the overall product and service development. This paper presents outcome of research project to investigate different approaches used by companies to analyse Service Requirements to achieve reduced Life Cycle Cost (LCC). Analysis using Weibull distribution and Monte Carlo principle have been proposed here; based on the conducted literature review these are considered as the most widely used techniques in product reliability studies. Based on those techniques, a methodology and its software tool for risk evaluation of failure to deliver a new product against Service Requirements are presented in this paper. This is part of the on-going research project which, apart from analysing the gap between the current Service Requirements achievements and the design targets for a new aircraft engine, it also facilitates an optimisation of those requirements at the minimum risk of nonconformity

    The Future of Nuclear Power in the United States: Economic and Regulatory Challenges

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    This paper examines the economic and regulatory challenges that must be faced by potential investors in new nuclear power plants in the United States. The historical development of the existing fleet of over 100 nuclear plants and their recent performance history are discussed. The pattern of re-licensing of existing plants and the implications for the role of the extended operation of the existing fleet in the overall electricity supply portfolio over the next 50 years is examined. The economic competitiveness of investments in new nuclear power plants compared to investments in alternative base load technologies is discussed under a variety of assumptions about construction costs, fuel costs, competitive and economic regulatory environments and various levels of carbon emissions prices affected competing fossil-fueled technologies. The paper then turns to a discussion of federal government efforts to facilitate investment in new nuclear power plants. These include streamlined licensing procedures and financial incentive provided by the Energy Policy Act of 2005. The regulatory and financial changes make investment in new nuclear power plants significantly more attractive to investors. However, in the longer run a combination of lower and more stable construction costs combined with carbon emissions charges are likely to be necessary to make investments in new nuclear plants significantly more attractive than investments in pulverized coal plants. Unresolved waste disposal policies and local opposition to new nuclear plants are likely to represent barriers to investment in new nuclear power plants in some areas of the country. First mover plants that can benefit from federal financial incentives are most likely to be built in states that continue to regulate generating plants based on cost-of-service principles, transferring construction cost and operating performance risks to consumers, and where there is room on existing sites to build additional nuclear capacity.

    TERMS: Techniques for electronic resources management

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    Librarians and information specialists have been finding ways to manage electronic resources for over a decade now. However, much of this work has been an ad hoc and learn-as-you-go process. The literature on electronic resource management shows this work as being segmented into many different areas of traditional librarian roles within the library. In addition, the literature show how management of these resources has driven the development of various management tools in the market as well as serve as the greatest need in the development of next generation library systems. TERMS is an attempt to create a series of on-going and continually developing set of management best practices for electronic resource management in libraries
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