5,165 research outputs found

    The Supply Shock Explanation of the Great Stagflation Revisited

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    U.S. inflation data exhibit two notable spikes into the double-digit range in 1973-1974 and again in 1978-1980. The well-known “supply-shock” explanation attributes both spikes to large food and energy shocks plus, in the case of 1973-1974, the removal of price controls. Yet critics of this explanation have (a) attributed the surges in inflation to monetary policy and (b) pointed to the far smaller impacts of more recent oil shocks as evidence against the supply-shock explanation. This paper reexamines the impacts of the supply shocks of the 1970s in the light of the new data, new events, new theories, and new econometric studies that have accumulated over the past quarter century. We find that the classic supply-shock explanation holds up very well; in particular, neither data revisions nor updated econometric estimates substantially change the evaluations of the 1972-1983 period that were made 25 years (or more) ago. We also rebut several variants of the claim that monetary policy, rather than supply shocks, was really to blame for the inflation spikes. Finally, we examine several changes in the economy that may explain why the impacts of oil shocks are so much smaller now than they were in the 1970s.

    Identifying harmonic attributes from online partial discharge data

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    Partial discharge (PD) monitoring is a key method of tracking fault progression and degradation of insulation systems. Recent research discovered that the harmonic regime experienced by the plant also affects the PD pattern, questioning the conclusions about equipment health drawn from PD data. This paper presents the design and creation of an online system for harmonic circumstance monitoring of distribution cables, using only PD data. Based on machine learning techniques, the system can assess the prevalence of the 5th and 7th harmonic orders over the monitoring period. This information is key for asset managers to draw correct conclusions about the remaining life of polymeric cable insulation, and prevent overestimation of the degradation trend

    Interpretation of partial discharge activity in the presence of harmonics

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    Recent work has identified that circumstances of equipment operation can radically change condition monitoring data. This contribution investigates the significance of considering circumstance monitoring on the diagnostic interpretation of such condition monitoring data. Electrical treeing partial discharge data have been subjected to a data mining investigation, providing a platform for classification of harmonic influenced partial discharge patterns. The Total Harmonic Distortion (THD) index was varied to a maximum of 40%. The results show progressive development for interpretation of condition monitoring data, improving the asset manager's holistic view of an asset's health

    The role of circumstance monitoring on the diagnostic interpretation of condition monitoring data

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    Circumstance monitoring, a recently coined termed defines the collection of data reflecting the real network working environment of in-service equipment. This ideally complete data set should reflect the elements of the electrical, mechanical, thermal, chemical and environmental stress factors present on the network. This must be distinguished from condition monitoring, which is the collection of data reflecting the status of in-service equipment. This contribution investigates the significance of considering circumstance monitoring on diagnostic interpretation of condition monitoring data. Electrical treeing partial discharge activity from various harmonic polluted waveforms have been recorded and subjected to a series of machine learning techniques. The outcome provides a platform for improved interpretation of the harmonic influenced partial discharge patterns. The main conclusion of this exercise suggests that any diagnostic interpretation is dependent on the immunity of condition monitoring measurements to the stress factors influencing the operational conditions. This enables the asset manager to have an improved holistic view of an asset's health

    Assessing the effects of power quality on partial discharge behaviour through machine learning

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    Partial discharge (PD) is commonly used as an indicator of insulation health in high voltage equipment, but research has indicated that power quality, particularly harmonics, can strongly influence the discharge behaviour and the corresponding pattern observed. Unacknowledged variation in harmonics of the excitation voltage waveform can influence the insulation's degradation, leading to possible misinterpretation of diagnostic data and erroneous estimates of the insulation's ageing state, thus resulting in inappropriate asset management decisions. This paper reports on a suite of classifiers for identifying pertinent harmonic attributes from PD data, and presents results of techniques for improving their accuracy. Aspects of PD field monitoring are used to design a practical system for on-line monitoring of voltage harmonics. This system yields a report on the harmonics experienced during the monitoring period

    Civil and Criminal Enforcement of the Clean Air Act After the 1990 Amendments

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    The Clean Air Act Amendments of 1990 formed one of the most sweeping revisions of any federal environmental statute in recent history. A wide array of technical improvements to existing provisions were joined with entirely new substantive programs aimed at controlling such diverse concerns as the development of new fuels, reduction of acid rain, ozone depletion, and even global warming. Aside from its ambitious substantive programs, however, the 1990 Amendments were driven by a recognition that the existing Clean Air Act had become largely unenforceable. Thus, the Amendments greatly expand the government\u27s enforcement authority, and provide a host of new enforcement options. In this article, the authors discuss these changes to the civil and criminal enforcement provisions of the Act, and examine how these revisions seem to contain a mixture of strengths and weaknesses that raise as many concerns as they do hopes that the new Act will better achieve the goal of protecting and enhancing the quality of the Nation\u27s air

    NASA micromin computer Monthly progress letter, Jan. 1967

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    Microminiature circuit development for flight control computer

    Drag Reduction by Polymers in Wall Bounded Turbulence

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    We address the mechanism of drag reduction by polymers in turbulent wall bounded flows. On the basis of the equations of fluid mechanics we present a quantitative derivation of the "maximum drag reduction (MDR) asymptote" which is the maximum drag reduction attained by polymers. Based on Newtonian information only we prove the existence of drag reduction, and with one experimental parameter we reach a quantitative agreement with the experimental measurements.Comment: 4 pages, 1 fig., included, PRL, submitte

    Comparison of quantum mechanical and classical trajectory calculations of cross sections for ion-atom impact ionization of negative - and positive -ions for heavy ion fusion applications

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    Stripping cross sections in nitrogen have been calculated using the classical trajectory approximation and the Born approximation of quantum mechanics for the outer shell electrons of 3.2GeV I^{-} and Cs+^{+} ions. A large difference in cross section, up to a factor of six, calculated in quantum mechanics and classical mechanics, has been obtained. Because at such high velocities the Born approximation is well validated, the classical trajectory approach fails to correctly predict the stripping cross sections at high energies for electron orbitals with low ionization potential.Comment: submitted to Phys. Rev.
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