32,879 research outputs found

    Environmental assessment overview

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    The assessment program has as its objectives: to identify the environmental issues associated with the SPS Reference System; to prepare a preliminary assessment based on existing data; to suggest mitigating strategies and provide environmental data and guidance to other components of the program as required; and to plan long-range research to reduce the uncertainty in the preliminary assessment. The key environmental issues associated with the satellite power system are discussed and include human health and safety, ecosystems, climate, and interaction with electromagnetic systems

    Study on needs for a magnetic suspension system operating with a transonic wind tunnel

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    The U.S. aeronautical industry was surveyed to determine if current and future transonic testing requirements are sufficient to justify continued development work on magnetic suspension and balance systems (MSBS) by NASA. The effort involved preparation of a brief technical description of magnetic suspension and balance systems, design of a survey form asking specific questions about the role of the MSBS in satisfying future testing requirements, selecting nine major aeronautics companies to which the description and survey forms were sent, and visiting the companies and discussing the survey to obtain greater insight to their response to the survey. Evaluation and documentation of the survey responses and recommendations which evolved from the study are presented

    EUROPE’S LONG TERM CLIMATE TARGET: A CRITICAL EVALUATION

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    The European Commission and a number of its Member States have adopted a stringent long-term target for climate policy, namely that the global mean temperature should not rise more than 2°C above pre-industrial times. This target is supported by rather thin arguments, based on inadequate methods, sloppy reasoning, and selective citation. In the scientific literature on “dangerous interference with the climate system”, most studies discuss either methodological issues, or carefully lay out the arguments for or against a particular target. These studies do not make specific recommendations, with the exception of cost-benefit analyses which argue for less stringent policy targets. However, there are also a few studies that recommend a target without the supporting argumentation. Overall, the 2°C target of the EU seems unfounded.Climate policy, Article 2, dangerous interference, European Union

    A contribution to supply chain design under uncertainty

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    Dans le contexte actuel des chaînes logistiques, des processus d'affaires complexes et des partenaires étendus, plusieurs facteurs peuvent augmenter les chances de perturbations dans les chaînes logistiques, telles que les pertes de clients en raison de l'intensification de la concurrence, la pénurie de l'offre en raison de l'incertitude des approvisionnements, la gestion d'un grand nombre de partenaires, les défaillances et les pannes imprévisibles, etc. Prévoir et répondre aux changements qui touchent les chaînes logistiques exigent parfois de composer avec des incertitudes et des informations incomplètes. Chaque entité de la chaîne doit être choisie de façon efficace afin de réduire autant que possible les facteurs de perturbations. Configurer des chaînes logistiques efficientes peut garantir la continuité des activités de la chaîne en dépit de la présence d'événements perturbateurs. L'objectif principal de cette thèse est la conception de chaînes logistiques qui résistent aux perturbations par le biais de modèles de sélection d'acteurs fiables. Les modèles proposés permettent de réduire la vulnérabilité aux perturbations qui peuvent aV, oir un impact sur la continuité des opérations des entités de la chaîne, soient les fournisseurs, les sites de production et les sites de distribution. Le manuscrit de cette thèse s'articule autour de trois principaux chapitres: 1 - Construction d'un modèle multi-objectifs de sélection d'acteurs fiables pour la conception de chaînes logistiques en mesure de résister aux perturbations. 2 - Examen des différents concepts et des types de risques liés aux chaînes logistiques ainsi qu'une présentation d'une approche pour quantifier le risque. 3 - Développement d'un modèle d'optimisation de la fiabilité afin de réduire la vulnérabilité aux perturbations des chaînes logistiques sous l'incertitude de la sollicitation et de l'offre

    Social science perspectives on natural hazards risk and uncertainty

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    Design and initial validation of the Raster method for telecom service availability risk assessment

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    Crisis organisations depend on telecommunication services; unavailability of these services reduces the effectiveness of crisis response. Crisis organisations should therefore be aware of availability risks, and need a suitable risk assessment method. Such a method needs to be aware of the exceptional circumstances in which crisis organisations operate, and of the commercial structure of modern telecom services. We found that existing risk assessment methods are unsuitable for this problem domain. Hence, crisis organisations do not perform any risk assessment, trust their supplier, or rely on service level agreements, which are not meaningful during crisis situations. We have therefore developed a new risk assessment method, which we call RASTER. We have tested RASTER using a case study at the crisis organisation of a government agency, and improved the method based on the analysis of case results. Our initial validation suggests that the method can yield practical results

    Analysis of the Copenhagen Accord pledges and its global climatic impacts‚ a snapshot of dissonant ambitions

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    This analysis of the Copenhagen Accord evaluates emission reduction pledges by individual countries against the Accord's climate-related objectives. Probabilistic estimates of the climatic consequences for a set of resulting multi-gas scenarios over the 21st century are calculated with a reduced complexity climate model, yielding global temperature increase and atmospheric CO2 and CO2-equivalent concentrations. Provisions for banked surplus emission allowances and credits from land use, land-use change and forestry are assessed and are shown to have the potential to lead to significant deterioration of the ambition levels implied by the pledges in 2020. This analysis demonstrates that the Copenhagen Accord and the pledges made under it represent a set of dissonant ambitions. The ambition level of the current pledges for 2020 and the lack of commonly agreed goals for 2050 place in peril the Accord's own ambition: to limit global warming to below 2 °C, and even more so for 1.5 °C, which is referenced in the Accord in association with potentially strengthening the long-term temperature goal in 2015. Due to the limited level of ambition by 2020, the ability to limit emissions afterwards to pathways consistent with either the 2 or 1.5 °C goal is likely to become less feasibl

    Geoengineering the climate: science, governance and uncertainty

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    Geoengineering, or the deliberate large-scale manipulation of the planetary environment to counteract anthropogenic climate change, has been suggested as a new potential tool for addressing climate change. Efforts to address climate change have primarily focused on mitigation, the reduction of greenhouse gas emissions, and more recently on addressing the impacts of climate change—adaptation. However, international political consensus on the need to reduce emissions has been very slow in coming, and there is as yet no agreement on the emissions reductions needed beyond 2012. As a result global emissions have continued to increase by about 3% per year (Raupach et al. 2007), a faster rate than that projected by the Intergovernmental Panel on Climate Change (IPCC) (IPCC 2001)7 even under its most fossil fuel intensive scenario (A1FI8) in which an increase in global mean temperature of about 4°C (2.4 to 6.4°C) by 2100 is projected (Rahmstorf et al. 2007). The scientifi c community is now becoming increasingly concerned that emissions will not be reduced at the rate and magnitude required to keep the increase in global average temperature below 2°C (above pre-industrial levels) by 2100. Concerns with the lack of progress of the political processes have led to increasing interest in geoengineering approaches. This Royal Society report presents an independent scientifi c review of the range of methods proposed with the aim of providing an objective view on whether geoengineering could, and should, play a role in addressing climate change, and under what conditions

    Trust and Risk Relationship Analysis on a Workflow Basis: A Use Case

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    Trust and risk are often seen in proportion to each other; as such, high trust may induce low risk and vice versa. However, recent research argues that trust and risk relationship is implicit rather than proportional. Considering that trust and risk are implicit, this paper proposes for the first time a novel approach to view trust and risk on a basis of a W3C PROV provenance data model applied in a healthcare domain. We argue that high trust in healthcare domain can be placed in data despite of its high risk, and low trust data can have low risk depending on data quality attributes and its provenance. This is demonstrated by our trust and risk models applied to the BII case study data. The proposed theoretical approach first calculates risk values at each workflow step considering PROV concepts and second, aggregates the final risk score for the whole provenance chain. Different from risk model, trust of a workflow is derived by applying DS/AHP method. The results prove our assumption that trust and risk relationship is implicit

    An experimental approach to project risk identification and prioritization

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    One of the aims of a broad ethnographic study into how the apportionment of risk influences pricing levels of contactors was to ascertain the significant risks affecting contractors in Ghana, and their impact on prices. To do this, in the context of contractors, the difference between expected and realized return on a project is the key dependent variable examined using documentary analyses and semi-structured interviews. Most work in this has focused on identifying and prioritising risks using relative importance indices generated from the analysis of questionnaire survey responses. However, this approach may be argued to constitute perceptions rather than direct measures of the project risk. Here, instead, project risk is investigated by examining two measures of the same quantity; one ‘before’ and one ‘after’ construction of a project has taken place. Risks events are identified by ascertaining the independent variables causing deviations between expected and actual rates of return. Risk impact is then measured by ascertaining additions or reductions to expected costs due to the occurrence of risk events. So far, data from eight substantially complete building projects indicates that consultants’ inefficiency, payment delays, subcontractor-related problems and changes in macroeconomic factors are significant risks affecting contractors in Ghana
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