1,021 research outputs found

    The Geoscience of Climate and Energy 1. Understanding the Climate System, and the Consequences of Climate Change for the Exploitation and Management of Natural Resources: The View from Banff

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    A commonly expressed opinion within the earth-science community is that the work of the Intergovernmental Panel on Climate Change (IPCC) has largely ignored paleoclimate data and the methods of research utilized by earth scientists. It can be demonstrated that this is not the case, and one of the objectives of the Gussow–Nuna conference was to present current research in this area. Whereas earth scientists might seem ideally placed to address issues of climate change and energy, many of the beliefs that inform public opinion about global warming and climate change are based on misrepresentations or over-simplifications. Six examples are discussed here, including mis-perceptions about the melting and retreat of glaciers, the true causes of concern about the future fate of polar bears, and myths about petroleum pricing and availability. There is ample space for the earth-science community to add its informed voice to debates about energy and climate change, but, to date, this voice appears to be have been largely ineffective. RÉSUMÉ Dans le milieu des sciences de la Terre on a souvent l’opinion que les travaux du Groupe d'experts intergouverne-mental sur l'Ă©volution du climat (GIEC) ont largement ignorĂ© les donnĂ©es et les mĂ©thodes de recherche palĂ©oclimatiques employĂ©es par les gĂ©oscientiques. On peut prouver que ce n’est pas le cas, et que c’était un des objectifs de la ConfĂ©rence Gussow− Nuna que de prĂ©senter les recherches actuelles en la matiĂšre. Bien qu’il semble que les gĂ©oscientifiques soient les mieux placĂ©s pour traiter de questions de changement climatique et d’énergie, de nombreuses croyances qui modĂšlent l’opinion publique sur le rĂ©chauffement global et le changement climatique reposent sur des informations trompeuses ou des simplifications excessives. Six exemples seront discutĂ©es ci-dessous, dont les perceptions erronĂ©es sur la fonte et le retrait des glaciers, les vĂ©ritables motifs d’inquiĂ©tude sur le sort des ours blancs, et la saga des prix et de la disponibilitĂ© du pĂ©trole. Nombreux sont les forums oĂč les gĂ©oscientifiques peuvent faire entendre leur voix compĂ©tentes dans les dĂ©bats sur l’énergie et le changement climatique, mais il semble que cela ait Ă©tĂ© sans grand effet jusqu’à maintenant

    A Phanerozoic Time Chart for Canada

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    Geoscience of Climate and Energy 10. The Alberta Oil Sands: Developing a New Regime of Environmental Management, 2010–2013

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        DOI: http://dx.doi.org/10.12789/geocanj.2013.40.01

    The Geoscience of Climate and Energy: An Introduction

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    Environmental Management of the Alberta Oil Sands: Introduction to the Special Set of Articles

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         DOI: http://dx.doi.org/10.12789/geocanj.2013.40.01

    Geoscience of Climate and Energy 13. The Environmental Hydrogeology of the Oil Sands, Lower Athabasca Area, Alberta

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    Shallow fresh groundwater and deep saline groundwater are used together with surface water in the extraction of bitumen from the Athabasca Oil Sands both in the surface mining and in situ operations. However, increasing efficiencies in processing technologies have reduced water use substantially and currently at least 75% of the water used in most operations is recycled water. Much concern has been expressed regarding contamination of surface waters by seepage from tailings ponds, but hydrogeological studies indicate that this is not happening; that seepage capture design is effective. Oil sands mining and in situ project licensing and operation regulations include Environmental Impact Assessments that mandate considerable hydrogeological measurement and monitoring work. However, little of this is independently evaluated for accuracy or synthesized and interpreted for the public. Recent changes in Alberta environmental regulation, including the establishment of the Alberta Environmental Monitoring Management Board (in October 2012) are expected to bring new transparency to environmental management of Oil Sands operations.SOMMAIREOn utilise conjointement des eaux douce de faibles profondeur, des eaux souterraines salines profondes avec des eaux de surface dans l'extraction du bitume des sables bitumineux de l'Athabasca, tant dans le procĂ©dĂ© d’extraction in situ qu’en surface.  Par ailleurs, l’accroissement de l'efficacitĂ© des technologies de traitement a considĂ©rablement rĂ©duit la consommation d'eau et, Ă  l’heure actuelle, au moins 75% de l'eau utilisĂ©e dans la majoritĂ© des opĂ©rations est de l'eau recyclĂ©e.  Beaucoup d’inquiĂ©tude a Ă©tĂ© exprimĂ©e concernant la contamination des eaux de surface par la percolation des eaux des bassins de dĂ©cantation des rĂ©sidus, mais des Ă©tudes hydrogĂ©ologiques indiquent que ce n'est pas le cas, et que le concept de capture des infiltrations est efficace.  L’octroi de permis d’exploitation ainsi que les procĂ©dĂ©s d’exploitation des sables bitumineux, par extraction en surface ou in situ, comportent des Ă©valuations d’impact sur les milieux de vie, est assorti de mandats Ă©laborĂ©s de mesures hydrologiques et de suivi.  Cela dit, peu de ces mesures sont Ă©valuĂ©es de maniĂšre indĂ©pendante quant Ă  leur exactitude, leur mise en forme et leur interprĂ©tation pour le grand public.  Les changements rĂ©cents dans la rĂ©glementation environnementale en Alberta, y compris la mise en place du Alberta Environmental Monitoring Management Board (en Octobre 2012) devraient aboutir Ă  une nouvelle transparence de la gestion environnementale de l'exploitation des sables bitumineux.DOI: http://dx.doi.org/10.12789/geocanj.2013.40.01

    Logan Medallist 3. Making Stratigraphy Respectable: From Stamp Collecting to Astronomical Calibration

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    The modern science of stratigraphy is founded on a nineteenth-century empirical base – the lithostratigraphy and biostratigraphy of basin-fill successions. This stratigraphic record comprises the most complete data set available for reconstructing the tectonic and climatic history of Earth. However, it has taken two hundred years of evolution of concepts and methods for the science to evolve from what Ernest Rutherford scornfully termed “stamp collecting” to a modern dynamic science characterized by an array of refined methods for documenting geological rates and processes.    Major developments in the evolution of the science of stratigraphy include the growth of an ever-more precise geological time scale, the birth of sedimentology and basin-analysis methods, the influence of plate tectonics and, most importantly, the development, since the late 1970s, of the concepts of sequence stratigraphy. Refinements in these concepts have required the integration of all pre-existing data and methods into a modern, multidisciplinary approach, as exemplified by the current drive to apply the retrodicted history of Earth’s orbital behaviour to the construction of a high-precision ‘astrochronological’ time scale back to at least the Mesozoic record.    At its core, stratigraphy, like much of geology, is a field-based science. The field context of a stratigraphic sample or succession remains the most important starting point for any advanced mapping, analytical or modeling work.RÉSUMÉLa science moderne de la stratigraphie repose sur une base empirique du XIXe siĂšcle, soit la lithostratigraphie et la biostratigraphie de successions de remplissage de bassins sĂ©dimentaires.  Cette archive stratigraphique est constituĂ©e de la base de donnĂ©es la plus complĂšte permettant de reconstituer l’histoire tectonique et climatique de la Terre.  Cela dit, il aura fallu deux cents ans d’évolution des concepts et des mĂ©thodes pour que cette activitĂ© passe de l’état de « timbromanie », comme disait dĂ©daigneusement Ernest Rutherford, Ă  l’état de science moderne dynamique caractĂ©risĂ©e par sa panoplie de mĂ©thodes permettant de documenter les rythmes et processus gĂ©ologiques.   Les principaux dĂ©veloppements de l’évolution de la science de la stratigraphie proviennent de l’élaboration d’une Ă©chelle gĂ©ologique toujours plus prĂ©cise, l’avĂšnement de la sĂ©dimentologie et des mĂ©thodes d’analyse des bassins, de l’influence de la tectonique des plaques et, surtout du dĂ©veloppement depuis la fin des annĂ©es 1970, des concepts de stratigraphie sĂ©quentielle.  Des raffinements dans ces concepts ont nĂ©cessitĂ© l'intĂ©gration de toutes les donnĂ©es et mĂ©thodes existantes dans une approche moderne, multidisciplinaire, comme le montre ce mouvement actuel qui entend utiliser la reconstitution de l’histoire du comportement orbital de la Terre pour l’élaboration d’une Ă©chelle temporelle « astrochronologique » de haute prĂ©cision, remontant jusqu’au MĂ©sozoĂŻque au moins.     Comme pour la gĂ©ologie, la stratigraphie est une science de terrain.  Le contexte de terrain d’un Ă©chantillon stratigraphique ou d’une succession demeure le point de dĂ©part le plus important, pour tout travail sĂ©rieux de cartographie, d’analyse ou de modĂ©lisation

    Predictive feedback control and Fitts' law

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    Fitts’ law is a well established empirical formula, known for encapsulating the “speed-accuracy trade-off”. For discrete, manual movements from a starting location to a target, Fitts’ law relates movement duration to the distance moved and target size. The widespread empirical success of the formula is suggestive of underlying principles of human movement control. There have been previous attempts to relate Fitts’ law to engineering-type control hypotheses and it has been shown that the law is exactly consistent with the closed-loop step-response of a time-delayed, first-order system. Assuming only the operation of closed-loop feedback, either continuous or intermittent, this paper asks whether such feedback should be predictive or not predictive to be consistent with Fitts law. Since Fitts’ law is equivalent to a time delay separated from a first-order system, known control theory implies that the controller must be predictive. A predictive controller moves the time-delay outside the feedback loop such that the closed-loop response can be separated into a time delay and rational function whereas a non- predictive controller retains a state delay within feedback loop which is not consistent with Fitts’ law. Using sufficient parameters, a high-order non-predictive controller could approximately reproduce Fitts’ law. However, such high-order, “non-parametric” controllers are essentially empirical in nature, without physical meaning, and therefore are conceptually inferior to the predictive controller. It is a new insight that using closed-loop feedback, prediction is required to physically explain Fitts’ law. The implication is that prediction is an inherent part of the “speed-accuracy trade-off”
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