Adjustment of model parameters to estimate distribution transformers remaining lifespan

Currently, the electrical system in Argentina is working at its maximum capacity, decreasing the margin between the installed power and demanded consumption, and drastically reducing the service life of transformer substations due to overload (since the margin for summer peaks is small). The advent of the Smart Grids allows electricity distribution companies to apply data analysis techniques to manage resources more efficiently at different levels (avoiding damages, better contingency management, maintenance planning, etc.). The Smart Grids in Argentina progresses slowly due to the high costs involved. In this context, the estimation of the lifespan reduction of distribution transformers is a key tool to efficiently manage human and material resources, maximizing the lifetime of this equipment. Despite the current state of the smart grids, the electricity distribution companies can implement it using the available data. Thermal models provide guidelines for lifespan estimation, but the adjustment to particular conditions, brands, or material quality is done by adjusting parameters. In this work we propose a method to adjust the parameters of a thermal model using Genetic Algorithms, comparing the estimation values of top-oil temperature with measurements from 315 kVA distribution transformers, located in the province of Tucumán, Argentina. The results show that, despite limited data availability, the adjusted model is suitable to implement a transformer monitoring system.Fil: Jimenez, Victor Adrian. Universidad Tecnológica Nacional. Facultad Regional Tucumán. Centro de Investigación en Tecnologías Avanzadas de Tucumán; ArgentinaFil: Will, Adrian L. E.. Universidad Tecnológica Nacional. Facultad Regional Tucumán. Centro de Investigación en Tecnologías Avanzadas de Tucumán; ArgentinaFil: Gotay Sardiñas, Jorge. Universidad Tecnológica Nacional. Facultad Regional Tucumán. Centro de Investigación en Tecnologías Avanzadas de Tucumán; ArgentinaFil: Rodriguez, Sebastian Alberto. Universidad Tecnológica Nacional. Facultad Regional Tucumán. Centro de Investigación en Tecnologías Avanzadas de Tucumán; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Tucumán; Argentin

Understanding pit sites: storage, surplus and social complexity in Prehistoric Western Europe.

This is a pre-print of an article published in Journal of Archaeological Method and Theory. The final authenticated, peer-reviewed version is available online at: https://doi.org/10.1007/s10816-019-09429-7The importance of pits for archaeological inference can hardly be overstated, given their virtual omnipresence in the archaeological record. In Prehistoric Europe pits occasionally form large concentrations known as ‘pit sites’, where they are the most visible, sometimes the sole, remnants of past human activity. If we follow the generally accepted view of pits as grain storage containers, how can we interpret the social role played by places comprising hundreds or even thousands of pits? This paper is an attempt to shed light on this topic by summarising and critically analysing much of the current knowledge on storage of grain in non-industrial societies. We will start by gathering relevant and up-to-date experimental, ethnographic and historical data about the challenges that the storage of grain poses and how pits may have helped Prehistoric communities to overcome them. This will be followed by a discussion of their advantages and disadvantages relative to other methods: why would anybody use airtight pits instead of, for instance, weather-proofed raised granaries? Next, we will undertake an examination of the social and economic contexts in which storage pits are an effective solution as opposed to those in which their performance is far from optimal. The conclusions drawn will serve as a background against which to evaluate current interpretations concerning three selected case studies in Prehistoric Western Europe.The research leading to these results has received funding from the PEOPLE Programme (Marie Curie Actions) of the European Union's Seventh Framework Programme (FP7/2007-2013) under REA grant agreement nº 2012-326129

The Dark Side of Monetary Bonuses:Theory and Experimental Evidence

To incentivize workers and boost performance, firms often offer monetary bonuses for the achievement of production goals. Such bonuses appeal to two types of motivations of the worker. On the one hand, the existence of a goal, on its own, triggers an intrinsic motivation associated with the desire to not fall short of the goal. On the other hand, the money paid to achieve the goal constitutes an extrinsic motivation. This paper studies the possibility that these two effects are substitutes when workers set their own goals. We develop a theoretical model that predicts that if the worker is sufficiently loss averse and faces uncertainty about reaching a production goal, offering a monetary payment contingent on reaching such a goal is counterproductive. This is because under the presence of monetary bonuses, the loss averse worker prefers setting lower goals, which yield lower but more likely bonus payments. Lower goals, in turn, negatively affect subsequent performance. Results from a laboratory experiment corroborate this prediction. This paper highlights the limits of monetary bonuses as an effective incentive when workers are loss averse