1,953 research outputs found

    Control in the technical societies: a brief history

    Get PDF
    By the time control engineering emerged as a coherent body of knowledge and practice (during and just after WW2) professional engineering societies had existed for many decades. Since control engineering is an interdisciplinary branch of the profession, new sections devoted to control were quickly established within the various existing technical societies. In addition, some new bodies devoted specifically or primarily to control were established. This article, a revised version of a paper presented at the IEEE 2009 Conference on the History of Technical Societies, describes how control engineering as a distinct branch of engineering became represented in technical societies in a number of countries

    Constraining a Historical Black Carbon Emission Inventory of the United States for 1960–2000

    Full text link
    We present an observationally constrained United States black carbon emission inventory with explicit representation of activity and technology between 1960 and 2000. We compare measured coefficient of haze data in California and New Jersey between 1965 and 2000 with predicted concentration trends and attribute discrepancies between observations and predicted concentrations among several sources based on seasonal and weekly patterns in observations. Emission factors for sources with distinct fuel trends are then estimated by comparing fuel and concentration trends and further substantiated by in‐depth examination of emission measurements. We recommend (1) increasing emission factors for preregulation vehicles by 80–250%; (2) increasing emission factors for residential heating stoves and boilers by 70% to 200% for 1980s and before; (3) explicitly representing naturally aspired off‐road engines for 1980s and before; and (4) explicitly representing certified wood stoves after 1985. We also evaluate other possible sources for discrepancy between model and measurement, including bias in modeled meteorology, subgrid spatial heterogeneity of concentrations, and inconsistencies in reported fuel consumption. The updated U.S. emissions are higher than the a priori estimate by 80% between 1960 and 1980, totaling 690 Gg/year in 1960 and 620 Gg/year in 1970 (excluding open burning). The revised inventory shows a strongly decreasing trend that was present in the observations but missing in the a priori inventory.Key PointsSystematic evaluation of long‐term U.S. black carbon observations identifies a small number of poorly estimated emission sourcesUpdated black carbon emission is higher than the previous estimate by 80% for 1960–1980, showing a decreasing trend as found in observationEmission factors for preregulation vehicles, off‐road engines, and residential heating stoves in 1980 and before should be increasedPeer Reviewedhttps://deepblue.lib.umich.edu/bitstream/2027.42/149266/1/jgrd55339_am.pdfhttps://deepblue.lib.umich.edu/bitstream/2027.42/149266/2/jgrd55339.pd

    Can Europe recover without credit?

    Get PDF
    Data from 135 countries covering five decades suggests that creditless recoveries, in which the stock of real credit does not return to the pre-crisis level for three years after the GDP trough, are not rare and are characterised by remarkable real GDP growth rates: 4.7 percent per year in middle-income countries and 3.2 percent per year in high-income countries. However, the implications of these historical episodes for the current European situation are limited, for two main reasons. First, creditless recoveries are much less common in highincome countries, than in low-income countries which are financially undeveloped. European economies heavily depend on bank loans and research suggests that loan supply played a major role in the recent weak credit performance of Europe. There are reasons to believe that, despite various efforts, normal lending has not yet been restored. Limited loan supply could be disruptive for the European economic recovery and there has been only a minor substitution of bank loans with debt securities. Second, creditless recoveries were associated with significant real exchange rate depreciation, which has hardly occurred so far in most of Europe. This stylised fact suggests that it might be difficult to re-establish economic growth in the absence of sizeable real exchange rate depreciation, if credit growth does not return

    Calculation of the positron bound state with the copper atom

    Get PDF
    A new relativistic method for calculation of positron binding to atoms is presented. The method combines a configuration interaction treatment of the valence electron and the positron with a many-body perturbation theory description of their interaction with the atomic core. We apply this method to positron binding by the copper atom and obtain the binding energy of 170 meV (+ - 10%). To check the accuracy of the method we use a similar approach to calculate the negative copper ion. The calculated electron affinity is 1.218 eV, in good agreement with the experimental value of 1.236 eV. The problem of convergence of positron-atom bound state calculations is investigated, and means to improve it are discussed. The relativistic character of the method and its satisfactory convergence make it a suitable tool for heavier atoms.Comment: 15 pages, 5 figures, RevTe

    The economic and innovation contribution of universities: a regional perspective

    Get PDF
    Universities and other higher education institutions (HEIs) have come to be regarded as key sources of knowledge utilisable in the pursuit of economic growth. Although there have been numerous studies assessing the economic and innovation impact of HEIs, there has been little systematic analysis of differences in the relative contribution of HEIs across regions. This paper provides an exploration of some of these differences in the context of the UK’s regions. Significant differences are found in the wealth generated by universities according to regional location and type of institution. Universities in more competitive regions are generally more productive than those located in less competitive regions. Also, traditional universities are generally more productive than their newer counterparts, with university productivity positively related to knowledge commercialisation capabilities. Weaker regions tend to be more dependent on their universities for income and innovation, but often these universities under-perform in comparison to counterpart institutions in more competitive regions. It is argued that uncompetitive regions lack the additional knowledge infrastructure, besides universities, that are more commonly a feature of more competitive regions

    Positron and positronium affinities in the work-formalism Hartree-Fock approximation

    Full text link
    Positron binding to anions is investigated within the work formalism proposed by Harbola and Sahni for the halide anions and the systems Li^- through O^- excluding Be^- and N^-. The toal ground-state energies of the anion-positron bound systems are empirically found to be an upper bound to the Hartree-Fock energies. The computed expectation values as well as positron and positronium affinities are in good agreement with their restricted Hartree-Fock counterparts. Binding of a positron to neutral species is also investigated using an iterative method.Comment: 12 pages, to appear in Physical Review
    • 

    corecore