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Abstract

We built a logistic regression Early Warning Models (EWM) for banking crises in a panel of 47 countries based on data from 1970-2014 using candidate variables that cover macro and financial market indicators. We find that VIX, a proxy of global risk-premium, has a strong signalling properties and that low VIX (low price of risk) increases likelihood of crisis. It does not only mean that stability leads to instability, but that this tends to be a global rather than a domestic phenomenon. We also find that particularly high contribution of financial sector to GDP growth often precedes crises, suggesting that such instances are primarily driven by excessive risk taking by financial sector and may not necessarily be sustainable. Other variables that feature prominently include credit and residential prices. Models using multiple variable clearly outperform single variable models, with probability of correct signal extraction exceeding 0.9. Our setting includes country-specific information without using country-specific effects in a regression, which allows for direct application of EWM we obtain to any country, including these that have not experienced a banking crisis.
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Authors and Affiliations

Piotr Bańbuła
1
Marcin Pietrzak
2

  1. Narodowy Bank Polski and Warsaw School of Economics
  2. Brown University and Institute of Economics, Polish Academy of Sciences
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Abstract

The paper presents the problem of coupling the gas flow dynamics in pipelines with the thermodynamics of hydrogen solubility in steel for the estimation of the fracture toughness. In particular, the influence of hydrogen blended natural gas transmission on hydrogen solubility and, consequently, on fracture toughness is investigated with a focus on the L485ME low-alloy steel grade. Hydraulic simulations are conducted to obtain the pressure and temperature conditions in the pipeline. The hydrogen content is calculated from Sievert’s law and, as a consequence, the fracture toughness of the base metal and heat-affected zone is estimated. Experimental data is used to define hydrogen-assisted crack size propagation in steel as well as to a plane strain fracture toughness. The simulations are conducted for a real natural gas transmission system and compared against the threshold stress intensity factor. The results showed that the computed fracture toughness for the heat-affected zone significantly decreases for all natural gas and hydrogen blends. The applied methodology allows for identification of the hydrogen-induced embrittlement susceptibility of pipelines constructed from thermomechanically rolled tubes worldwide most commonly used for gas transmission networks in the last few decades.
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Authors and Affiliations

Maciej Witek
1
Ferdinand Uilhoorn
1

  1. Warsaw University of Technology, Department of Heating and Gas Systems, Nowowiejska 20, 00-653 Warsaw, Poland

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