5,012 research outputs found

    Techniques for obtaining regional radiation budgets from satellite radiometer observations, phase 4 and phase 5

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    A scheme was developed which divides the earth-atmosphere system into 2060 elemental areas. The regions previously described are defined in terms of these elemental areas which are fixed in size and position as the satellite moves. One method, termed the instantaneous technique, yields values of the radiant emittance (We) and the radiant reflectance (Wr) which the regions have during the time interval of a single satellite pass. The number of observations matches the number of regions under study and a unique solution is obtained using matrix inversion. The other method (termed the best fit technique), yields time averages of We and Wr for large time intervals (e.g., months, seasons). The number of observations in this technique is much greater than the number of regions considered, and an approximate solution is obtained by the method of least squares

    Techniques for computing regional radiant emittances of the earth-atmosphere system from observations by wide-angle satellite radiometers, phase 3

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    Radiometers on earth orbiting satellites measure the exchange of radiant energy between the earth-atmosphere (E-A) system and space at observation points in space external to the E-A system. Observations by wideangle, spherical and flat radiometers are analyzed and interpreted with regard to the general problem of the earth energy budget (EEB) and to the problem of determining the energy budget of regions smaller than the field of view (FOV) of these radiometers

    Photoemission Spectra from Reduced Density Matrices: the Band Gap in Strongly Correlated Systems

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    We present a method for the calculation of photoemission spectra in terms of reduced density matrices. We start from the spectral representation of the one-body Green's function G, whose imaginary part is related to photoemission spectra, and we introduce a frequency-dependent effective energy that accounts for all the poles of G. Simple approximations to this effective energy give accurate spectra in model systems in the weak as well as strong correlation regime. In real systems reduced density matrices can be obtained from reduced density-matrix functional theory. Here we use this approach to calculate the photoemission spectrum of bulk NiO: our method yields a qualitatively correct picture both in the antiferromagnetic and paramagnetic phases, contrary to mean-field methods, in which the paramagnet is a metal

    Adjustment of Recall Errors in Duration Data Using SIMEX

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    It is widely accepted that due to memory failures retrospective survey questions tend to be prone to measurement error. However, the proportion of studies using such data that attempt to adjust for the measurement problem is shockingly low. Arguably, to a great extent this is due to both the complexity of the methods available and the need to access a subsample containing either a gold standard or replicated values. Here I suggest the implementation of a version of SIMEX capable of adjusting for the types of multiplicative measurement errors associated with memory failures in the retrospective report of durations of life-course events. SIMEX is a method relatively simple to implement and it does not require the use of replicated or validation data so long as the error process can be adequately specified. To assess the effectiveness of the method I use simulated data. I create twelve scenarios based on the combinations of three outcome models (linear, logit and Poisson) and four types of multiplicative errors (non-systematic, systematic negative, systematic positive and heteroscedastic) affecting one of the explanatory variables. I show that SIMEX can be satisfactorily implemented in each of these scenarios. Furthermore, the method can also achieve partial adjustments even in scenarios where the actual distribution and prevalence of the measurement error differs substantially from what is assumed in the adjustment, which makes it an interesting sensitivity tool in those cases where all that is known about the error process is reduced to an educated guess

    Revival and relevance: The walled kitchen garden in 21st century public history

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    Trelissick walled kitchen garden currently lies dormant at the heart of a thriving National Trust property on the outskirts of Truro in Cornwall. Created in the 18th century, this highly productive space fed and adorned the estate throughout its ever-evolving lifespan and numerous proprietors. The mid-20th century saw its decline and enforced state of redundancy, mirroring the fate met by many similar sites across the nation. The site now stands on the brink of regeneration. This thesis locates the public historic walled garden within the wider historiography and seeks to present a framework in which the National Trust can present the walled kitchen garden to a 21st century audience, one that respects its historic origins yet responds to the needs and wants of its visitors, all the while retaining relevance. Despite the development of wider historical discourse surrounding concepts of public history, history from below and new museology, the discipline of garden history has mostly fixated its gaze upon conventional elitist narratives which gravitate towards the 18th century British landscape movement. This thesis explores the limitations of such an approach, as well as the means by which garden history can reassess its dependence upon hegemonic discourse, thereby becoming more responsive and future oriented, embracing notions of co-curatorship and dialogue that are at the heart of alternative methodological perspectives such as new museology, public history and history from below. Thus, Trelissick’s walled garden has the potential to embody the manifestation of garden history – often regarded as a purely scholarly discipline – in historic gardens themselves

    Classe de Ciências

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    info:eu-repo/semantics/publishedVersio

    Stochastic evaluation of sewer inlet capacity on urban pluvial flooding

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    In this paper we present an innovative methodology to stochastically assess the impact of sewer inlet conditions on urban pluvial flooding. The results showed that sewer inlet capacity can have a large impact on the occurrence of urban pluvial flooding. The methodology is a useful tool for dealing with uncertainties in sewer inlet operational conditions and contribute to comprehensive assessment of urban pluvial risk assessment
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