Public Debt Frontiers: The Greek Case

This paper attempts to quantify the maximum amount of debt that a government can sustain by itself, i.e., the limits to public indebtedness. Using a Dynamic General Equilibrium model where the government is fully characterized, we compute the steady state inverse relationship between the public debt to output ratio and the size of the government, measured as the total public expenditures to output ratio. This line is the budget constraint of a government in steady state. Calibration of the model for the Greek economy to fiscal targets reveals that, for the period just before the current recession, i.e. 2002-2006, the debt to GDP ratio was very close to the calculate limits wich depends dramatically on the interest rates. However, short after de financial crisis of 2008, sustained deficits drove the Greek economy to a point where the Greek Government crossed the debt limit where the country could only meet its debt obligations only if international investors where willing to lend. We conclude that the hight initial level of debts previous the crisis together with the rise in interest rates were the causes of the posterior debt crisis.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tec

Public debt frontiers: The greek case

Las causas de la crisis de deuda Griega son otras distintas de la indisciplina fiscal. Los indicadores macroeconómicos desde el año 200 a 2006 no indicaban nada que pudiera presagiar el desastre. Causas de tipo estratégico en el manejo de la deuda parecen más razonables a la hora de explicar el fenómenoUniversidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

Economía sostenible : ¿mito o realidad?

El impacto económico sobre el entorno es clave a la hora de valorar los precios de un determinado bien, ya que su cantidad disminuirá y será sustituido por otro bien de menor coste. A esto se une una sostenibilidad amenazada por el aumento de la población y del uso abusivo de los recursos naturales

Fault detection in rotating machinery using acoustic emission

This thesis was submitted for the award of Doctor of Philosophy and was awarded by Brunel University LondonRotating machinery is a critical asset of industrial plants worldwide. Bearings and gearboxes are two of the most common components found in rotating machinery of industrial plants. The malfunction of bearings and gearboxes lead the machine to fail and often these failures occur catastrophically leading to personnel injuries. Therefore it is of high importance to identify the deterioration at an early stage. Among the techniques applied to detect damage in rotating machinery, acoustic emission has been a prevalent field of research for its potential to detect defects at an earlier stage than other more established techniques such as vibration analysis and oil analysis. However, to reliably detect the fault at an early stage de-noising techniques often must be applied to reduce the AE noise generated by neighbouring components and normal component operation. For this purpose a novel signal processing algorithm has been developed combining Wavelet Packets as a pre-processor, Hilbert Transform, Autocorrelation function and Fast Fourier transform. The combination of these techniques allows identification of g repetitive patterns in the AE signal that are attributable to bearing and gear damage. The enhancement for early stage defect detection in bearings and gears provided by this method is beneficial in planning maintenance in advance, reducing machinery down-time and consequently reducing the costs associated with bearing breakdown. The effectiveness of the proposed method has been investigated experimentally using seeded and naturally developed defects in gears and bearings. In addition, research into the optimal Wavelet Packet node that offers the best de-noising results has been performed showing that the 250-750 kHz band gives the best SNR results. The detection of shaft angular misalignment using Acoustic Emission has been investigated and compared with acceleration spectra. The results obtained show enhancements of AE in detection shaft angular misalignment over vibration analysis in SNR and stability with varying operational conditions

Language, exogamy and ethnicity in the Upper Rio Negro region

In this article we explore how languages interact with exogamous social units (e.g., clans and phratries) and descent ideologies (such as having a common mythical ancestor and emergence from the same mythical place) to help organize the multilingual and interethnic societies from the Upper Rio Negro region (URN) in the Amazon. We show that the expected alignment of language boundary, exogamous group and descent group is actually quite unusual. Complex social structures involving the aggregation of clans into larger ethnic groups or marriage alliances with other clans have important variations in the alignment of language, exogamy, and descent ideology. Existing alignments follow, in fact, a parametric variation that shed light on different contexts of multilingualism and interethnic relations. Given that language is one among many possible ethnic markers, and that no single ethnic marker is either necessary or sufficient to demarcate exogamous groups at any level of the system, we uncover the function of languages in URN societies in ambivalent processes that creating sameness and otherness within and across social units defined by affinity or common descent. This fluid and dynamic use of languages is grounded in social structure and interethnic relations, while simultaneously serving as a means to reinforce and change social and cultural relations