The economics of debt clearing mechanisms

We examine the evolution of decentralized clearinghouse mechanisms from the 13th to the 18th century; in particular, we explore the clearing of non- or limitedtradable debts like bills of exchange. We construct a theoretical model of these clearinghouse mechanisms, similar to the models in the theoretical matching literature, and show that specific decentralized multilateral clearing algorithms known as rescontre, skontrieren or virement des parties used by merchants were efficient in specific historical contexts. We can explain both the evolutionary self-organizing emergence of late medieval and early modern fairs, and its robustness during the 17th and 18th century

Simulation of the High Cycle Fatigue Life Reduction due to Internal Hydrogen Embrittlement Using a Commercial Finite Element Program

The effect of internal hydrogen on the high cycle fatigue (HCF) life duration of Inconel X-750® in the hydrogen concentration range between 5 and 39 wppm at ambient temperature was investigated using an ultrasonic HCF test bench. For an alternating stress equal to 0.6 times the yield stress of the hydrogen-free material, a drop of two orders of magnitude in the high-cycle fatigue durability of the material has been measured over the investigated hydrogen concentration range. New tools have been developed to predict with little efforts the drop in life duration due to internal hydrogen embrittlement and the localization of the fracture area by Finite Element simulations. A simple approach has been considered to rapidly get a first assessment of the drop magnitude in HCF life duration of a structure due to internal hydrogen embrittlement at steady state hydrogen concentration conditions. The core of this proposed Finite Element calculation-based method is the “double Wöhler curve”, i.e. a three-dimensional Wöhler curve with the hydrogen concentration as the third dimension