Formal series and numerical integrators: some history and some new techniques

This paper provides a brief history of B-series and the associated Butcher group and presents the new theory of word series and extended word series. B-series (Hairer and Wanner 1976) are formal series of functions parameterized by rooted trees. They greatly simplify the study of Runge-Kutta schemes and other numerical integrators. We examine the problems that led to the introduction of B-series and survey a number of more recent developments, including applications outside numerical mathematics. Word series (series of functions parameterized by words from an alphabet) provide in some cases a very convenient alternative to B-series. Associated with word series is a group G of coefficients with a composition rule simpler than the corresponding rule in the Butcher group. From a more mathematical point of view, integrators, like Runge-Kutta schemes, that are affine equivariant are represented by elements of the Butcher group, integrators that are equivariant with respect to arbitrary changes of variables are represented by elements of the word group G.Comment: arXiv admin note: text overlap with arXiv:1502.0552

Stream Learning in Energy IoT Systems: A Case Study in Combined Cycle Power Plants

The prediction of electrical power produced in combined cycle power plants is a key challenge in the electrical power and energy systems field. This power production can vary depending on environmental variables, such as temperature, pressure, and humidity. Thus, the business problem is how to predict the power production as a function of these environmental conditions, in order to maximize the profit. The research community has solved this problem by applying Machine Learning techniques, and has managed to reduce the computational and time costs in comparison with the traditional thermodynamical analysis. Until now, this challenge has been tackled from a batch learning perspective, in which data is assumed to be at rest, and where models do not continuously integrate new information into already constructed models. We present an approach closer to the Big Data and Internet of Things paradigms, in which data are continuously arriving and where models learn incrementally, achieving significant enhancements in terms of data processing (time, memory and computational costs), and obtaining competitive performances. This work compares and examines the hourly electrical power prediction of several streaming regressors, and discusses about the best technique in terms of time processing and predictive performance to be applied on this streaming scenario.This work has been partially supported by the EU project iDev40. This project has received funding from the ECSEL Joint Undertaking (JU) under grant agreement No 783163. The JU receives support from the European Union’s Horizon 2020 research and innovation programme and Austria, Germany, Belgium, Italy, Spain, Romania. It has also been supported by the Basque Government (Spain) through the project VIRTUAL (KK-2018/00096), and by Ministerio de Economía y Competitividad of Spain (Grant Ref. TIN2017-85887-C2-2-P)

Relevance theory and polítical advertising. A case study.

This paper aims to apply Sperber & Wilson?s Relevance Theory (1986; 1995; 1987) and the two stage incongruity-resolution theory of humour (Attardo 1994) to explain how humorous interpretations are produced in a corpus of political billboards published by the Labour Party in the 1997, 2001 and 2005 British election campaigns. The intersemiosis (O?Halloran 2008) between the verbal and the visual will be taken into account in order to decode the meanings transmitted. It will be suggested that the viewers? access to background beliefs and assumptions in order to form a context against which new incoming information can be processed is also essential in order to decode meaning. The extraction of strongly or weakly implicated information is a good source of humorous effects. It will also be suggested that the interpretation depends on the viewer?s ideology, as ?relevance is always relevance to an individual? (Sperber & Wilson 1986: 142)

Nuevas evidencias de Onuba

Las evidencias romanas halladas en Huelva, la vieja Onuba, se reducían a excavaciones realizadas en los años setenta en necrópolis y factorías de salazón. El presente articulo ofrece nuevos datos sobre el hasta hoy desconocido poblado y nos permiten establecer tres etapas: la importante segunda mitad del siglo i, el vacío existente por el momento durante el siglo II y la decadencia de los siglos III y IV

A Stroboscopic Numerical Method for Highly Oscillatory Problems

International audienceWe suggest a method for the integration of highly oscillatory systems with a single high frequency. The new method may be seen as a purely numerical way of implementing the analytical technique of stroboscopic averaging. The technique may be easily implemented in combination with standard software and may be applied with variable step sizes. Numerical experiments show that the suggested algorithms may be substantially more efficient than standard numerical integrators

Multidisciplinary Approach of Malignant Tumors of the Biliary Tree

Biliary tract carcinomas are aggressive tumors that arise from epithelial cells of bile ducts. They present several difficulties in their clinical management. A late initial diagnosis (frequently in the form of locally advanced disease), jaundice, cholangitis, or poor performance status of patients are some of the medical issues that arise in this setting. Another clinical limitation is the lack of robust evidence for many of the standard procedures in this particular scenario. Biliary tumors are lethal tumors, and most of them present in the form of advanced disease or during late evolution. However, we are witnessing some exciting changes in clinical management of tumors of the biliary tract, such as the development of new radiological techniques and novel interventional radiology procedures, the emergence of new radiotherapy modalities, the establishment of standardized chemotherapy regimens, the advance in molecular knowledge, and the development of new treatments directed against therapeutic targets. On the other hand, the most important step for advancing the treatment of these complex diseases is the appearance of multidisciplinary management teams integrating qualified specialists to resolve appropriate treatment challenges. In this chapter, we summarize the most relevant advances in clinical management and new oncologic treatment in biliary tract carcinomas

Activity of (2060) Chiron possibly caused by impacts?

The centaur 95P/(2060) Chiron is showing comet-like activity since its discovery, but the mass-loss mechanisms triggering its activity remained unexplained. Although the collision rates in the centaur region are expected to be very low, and impacts are thought not to be responsible for the mass-loss, since the recent indications that Chiron might possess a ring similar to Chariklo's, and assuming that there is debris orbiting around, the impact triggered mass-loss mechanism should not be excluded as a possible cause of its activity. From time series observations collected on Calar Alto Observatory in Spain between 2014 and 2016, we found that the photometric scatter in Chiron's data is larger than a control star's scatter, indicating a possible microactivity, possibly caused by debris falling back to Chiron's surface and lifting small clouds of material. We also present rotational light curves, and measurements of Chiron's absolute magnitudes, that are consistent with the models supporting the presumption that Chiron possesses rings. By co-adding the images acquired in 2015, we have detected a $\sim$5 arcsec long tail, showing a surface brightness of 25.3 mag(V)/arcsec$^{2}$.Comment: Accepted for publication in Monthly Notices of the Royal Astronomical Society (MNRAS) on 2017 December 2