A consistent interface element formulation for geometrical and material nonlinearities

Decohesion undergoing large displacements takes place in a wide range of applications. In these problems, interface element formulations for large displacements should be used to accurately deal with coupled material and geometrical nonlinearities. The present work proposes a consistent derivation of a new interface element for large deformation analyses. The resulting compact derivation leads to a operational formulation that enables the accommodation of any order of kinematic interpolation and constitutive behavior of the interface. The derived interface element has been implemented into the finite element codes FEAP and ABAQUS by means of user-defined routines. The interplay between geometrical and material nonlinearities is investigated by considering two different constitutive models for the interface (tension cut-off and polynomial cohesive zone models) and small or finite deformation for the continuum. Numerical examples are proposed to assess the mesh independency of the new interface element and to demonstrate the robustness of the formulation. A comparison with experimental results for peeling confirms the predictive capabilities of the formulation.Comment: 14 pages, 11 figure

What You Don\u27t Know About Motivational Laptop Stickers

Mental health problems are on the rise among young adults in the U.S. (Kingkade, 2016). At the same time, today’s U.S. young adults are significantly more invested than their older counterparts in portraying themselves as “positive” (self-confident, easy-going, and happy; Berenson et al., 2018). Although many have begun to speculate that these two trends may be linked (e.g., Fagan, 2017), little empirical research on this issue exists

Temporal characterization of the requests to Wikipedia

This paper presents an empirical study about the temporal patterns characterizing the requests submitted by users to Wikipedia. The study is based on the analysis of the log lines registered by the Wikimedia Foundation Squid servers after having sent the appropriate content in response to users' requests. The analysis has been conducted regarding the ten most visited editions of Wikipedia and has involved more than 14,000 million log lines corresponding to the traffic of the entire year 2009. The conducted methodology has mainly consisted in the parsing and filtering of users' requests according to the study directives. As a result, relevant information fields have been finally stored in a database for persistence and further characterization. In this way, we, first, assessed, whether the traffic to Wikipedia could serve as a reliable estimator of the overall traffic to all the Wikimedia Foundation projects. Our subsequent analysis of the temporal evolutions corresponding to the different types of requests to Wikipedia revealed interesting differences and similarities among them that can be related to the users' attention to the Encyclopedia. In addition, we have performed separated characterizations of each Wikipedia edition to compare their respective evolutions over time

A quantitative examination of the impact of featured articles in Wikipedia

This paper presents a quantitative examination of the impact of the presentation of featured articles as quality content in the main page of several Wikipedia editions. Moreover, the paper also presents the analysis performed to determine the number of visits received by the articles promoted to the featured status. We have analyzed the visits not only in the month when articles awarded the promotion or were included in the main page, but also in the previous and following ones. The main aim for this is to assess the attention attracted by the featured content and the different dynamics exhibited by each community of users in respect to the promotion process. The main results of this paper are twofold: it shows how to extract relevant information related to the use of Wikipedia, which is an emerging research topic, and it analyzes whether the featured articles mechanism achieve to attract more attention

Análisis de controladores por realimentación de estados, control óptimo y lógica difusa, para un péndulo de Furuta

Este trabajo presenta el desarrollo y control de un péndulo invertido rotacional (péndulo de Furuta) mediante controladores en el espacio de estados, control óptimo y lógica difusa. Este tipo de sistemas son las aeronaves, vehículos espaciales, vehículos submarinos, barcos, satélites y robots, construidos por barras y uniones articuladas, pasivas y activas. Estos sistemas generalmente están desafiando a la gravedad y deben mantenerse en equilibrio, por lo tanto, las plantas de estos sistemas son no lineales y se hace necesario controlarlo mediante leyes de control no lineales; sin embargo, debido al aparecimiento de la lógica difusa, este tipo de control tiene una gran ventaja que radica en que no es necesario saber con exactitud las características de la planta; el control puede ser adaptado para sistemas SISO y MIMO; la clave del control difuso radica especialmente en el conocimiento que debe tener el experto para plantear los rangos de las funciones de inferencia y su tipo de funciones, además, plantear el método de inferencia de la máquina de inferencia; por lo tanto, para este tipo de control se debe hacer varias pruebas hasta conseguir los objetivos planteados en el sistema de control.This paper presents the development and control of a rotational inverted pendulum (Furuta pendulum) by controllers in the state space, optimal control and fuzzy logic. Such systems are aircraft, spacecraft, underwater vehicles, ships, satellites and robots, built by rods and articulated joints, passive and active. These systems generally are defying gravity to stay in balance so plants such systems are nonlinear and will need to be monitored by nonlinear control laws however due to the appearance of fuzzy logic, this control has great advantage is that it is not necessary to know exactly the characteristics of the plant and control systems can be adapted to Simple Simple Input Output (SISO) or Multiple Input Multiple Output (MIMO), the key lies especially fuzzy control in the knowledge that you need to ask the expert ranges inference functions and features such well raise the inference method of inference engine, so for this type of control should be done several tests to get the goals set in the control system

Preliminary check-list of the bryophytes of Extremadura (Spain)

A list of all bryophytes recorded for Extremadura in the literature from 1802 to 2010 is provided. It includes 390 taxa (4 hornworts, 87 liverworts and 299 mosses). Information on the presence of these taxa in each of the Extremaduran provinces (Cáceres and Badajoz) is included. In addition, the conservation status of these species is added

Fracture of solar-grade anisotropic polycrystalline Silicon: A combined phase field–cohesive zone model approach

Artículo Open Access en el sitio web del editor. Pago por publicar en abierto. This work presents a novel computational framework to simulate fracture events in brittle anisotropic polycrystalline materials at the microscopical level, with application to solar-grade polycrystalline Silicon. Quasi-static failure is modeled by combining the phase field approach of brittle fracture (for transgranular fracture) with the cohesive zone model for the grain boundaries (for intergranular fracture) through the generalization of the recent FE-based technique published in [M. Paggi, J. Reinoso, Comput. Methods Appl. Mech. Engrg., 31 (2017) 145–172] to deal with anisotropic polycrystalline microstructures. The proposed model, which accounts for any anisotropic constitutive tensor for the grains depending on their preferential orientation, as well as an orientation-dependent fracture toughness, allows to simulate intergranular and transgranular crack growths in an efficient manner, with or without initial defects. One of the advantages of the current variational method is the fact that complex crack patterns in such materials are triggered without any user-intervention, being possible to account for the competition between both dissipative phenomena. In addition, further aspects with regard to the model parameters identification are discussed in reference to solar cells images obtained from transmitted light source. A series of representative numerical simulations is carried out to highlight the interplay between the different types of fracture occurring in solar-grade polycrystalline Silicon, and to assess the role of anisotropy on the crack path and on the apparent tensile strength of the material. Unión Europea FP/2007–2013/ERC 306622 Ministerio de Economía y Competitividad MAT2015–71036-P y MAT2015–71309-P Junta de Andalucía P11-TEP-7093 y P12-TEP- 105