Failure analysis of a plastic modular belt in-service

[EN] In this study, an analysis of the possible causes of the failure in-service of a section of a plastic modular belt was conducted. The study begins with a reproduction of the service conditions in a traction gear. An analysis of the fracture surfaces revealed the existence of defects in the interior of the parts. With the aim of determining the origin of the imperfections and their influence on the failure, an exhaustive mechanical and rheological characterization of the material was carried out. The development of an FE Analysis established that the reduction of the tensile strength of the part due to internal defects was around 70%. Tests also showed that the most stressed area was the area where the most defects appeared. A simulation of the injection process showed that the defects are caused by the geometry of the part, leading to the conclusion that its failure was caused by bad dimensioning of thicknesses.Sanchez-Caballero, S.; Sellés Cantó, MÁ.; Ferrándiz Bou, S.; Peydro, MA.; Oliver, B. (2018). Failure analysis of a plastic modular belt in-service. Engineering Failure Analysis. 93:13-25. https://doi.org/10.1016/j.engfailanal.2018.06.019S13259

Different abundance and correlational patterns exist between total and presumed pathogenic Vibrio vulnificus and V. parahaemolyticus in shellfish and waters along the North Carolina coast

Monitoring of Vibrio vulnificus and V. parahaemolyticus abundance is pertinent due to the ability of these species to cause disease in humans through aquatic vectors. Previously, we performed a multiyear investigation tracking Vibrio spp. levels in five sites along the southeastern North Carolina coast. From February 2013 to October 2015, total V. vulnificus and V. parahaemolyticus abundance was measured in water, oysters and clams. In the current study, pathogenic subpopulations were identified in these isolates using molecular markers, revealing that 5.3% of V. vulnificus isolates possessed the virulence-correlated gene (vcgC), and 1.9% of V. parahaemolyticus isolates harbored one or both of the virulence-associated hemolysin genes (tdh and trh). Total V. parahaemolyticus abundance was not sufficient to predict the abundance of pathogenic subpopulations. Specifically, pathogenic V. parahaemolyticus isolates were more often isolated in cooler waters and were sometimes isolated when no other V. parahaemolyticus strains were detectable. Vibrio vulnificus clinical (C-) genotypes correlated with total V. vulnificus; however, salinity, water depth and total suspended solids influenced C- and E-genotypes differently. Lastly, we documented individual oysters harboring significantly higher V. vulnificus levels for which there was no ecological explanation, a phenomenon that deserves closer attention due to the potentially elevated health hazard associated with these 'hot' shellfish. We tested environmentally isolated Vibrio vulnificus and V. parahaemolyticus isolates for the presence of virulence markers and found that pathogenic subpopulations do not necessarily reflect total species abundance and correlation patterns

Palaeoenvironmental analysis of the Aragonian (middle Miocene) mammalian faunas from the Madrid Basin based on body-size structure

As a consequence of the growth of the Antarctic ice-sheet during the middle Miocene, a global decrease of temperatures and an associated increase in aridity provoked several environmental changes all around the world. Such environmental variations can be detected in the continental record of the mammalian prey community structure using a synecological approach. Because of the good quality of its faunas, the rich Aragonian vertebrate fossil record from the Madrid Basin (Spain) appears as a good candidate to explore these environmental changes. In order to analyse the climatic evolution of the Iberian Peninsula associated to the Global Cooling Event, two classic palaeosynecological methodologies (cenograms and body size diversity), based on body-size community structure, were applied to 6 fossil sites from the Madrid Basin, ranging over 2 million years (15.5 – 13.5 Ma). To establish a comparative framework, we used the ecological faunal data from 100 modern localities uniformly distributed all around the world. Our palaeoenvironmental inference is based on multivariate discriminant analysis of the dataset containing both modern and fossil mammals. Finally, we can conclude that the Aragonian mammalian assemblage from the Madrid Basin showed a predominance of semiarid environments with pulses of higher aridity in biozones Dc, E and F associated with the Global Cooling Event of the middle Miocene.Como consecuencia del crecimiento del casquete polar Antártico, durante el Mioceno medio, se produjo un descenso global de la tem­peratura asociado a un aumento de la aridez. Este tipo de cambios ambientales pueden ser detectados en el registro continental, siguiendo un modelo sinecológico para analizar la estructura de las comunidades de las faunas de mamíferos herbívoros. Debido a la calidad de sus faunas, el registro fósil de las faunas de vertebrados del Aragoniense de la Cuenca de Madrid se antoja como un buen candidato para explorar estos patrones de cambio ambiental. Con el objetivo de analizar la evolución climática de la Península Ibérica asociada al evento de enfriamiento global durante este lapso temporal, dos metodologías paleosinecológicas clásicas (cenogramas y espectros de diversidad de tamaño corporal), basadas en la estructura de tamaños corporales de las comunidades de mamíferos, han sido aplicadas a la fauna de herbívoros fósiles presente en seis yacimientos de la Cuenca de Madrid, abarcando aproximadamente 2 millones de años (15.5 – 13.5 Ma). Se ha establecido un marco comparativo usando los datos ecológicos de la fauna de mamíferos presente en 100 localidades uniformemente distribuidas por todo el planeta. Esta inferencia paleoambiental está basada en la aplicación de análisis discriminante multivariante sobre el conjunto de datos de las faunas actuales y fósiles. Finalmente, las faunas de mamíferos del Aragoniense de la Comunidad de Madrid mostraron una predominancia de ambientes semiáridos con varios pulsos de mayor aridez en las biozonas Dc, E y F asociados al evento de enfriamiento global del Mioceno medio

Unified Dark Matter models with fast transition

We investigate the general properties of Unified Dark Matter (UDM) fluid models where the pressure and the energy density are linked by a barotropic equation of state (EoS) $p = p(\rho)$ and the perturbations are adiabatic. The EoS is assumed to admit a future attractor that acts as an effective cosmological constant, while asymptotically in the past the pressure is negligible. UDM models of the dark sector are appealing because they evade the so-called "coincidence problem" and "predict" what can be interpreted as $w_{\rm DE} \approx -1$, but in general suffer the effects of a non-negligible Jeans scale that wreak havoc in the evolution of perturbations, causing a large Integrated Sachs-Wolfe effect and/or changing structure formation at small scales. Typically, observational constraints are violated, unless the parameters of the UDM model are tuned to make it indistinguishable from $\Lambda$CDM. Here we show how this problem can be avoided, studying in detail the functional form of the Jeans scale in adiabatic UDM perturbations and introducing a class of models with a fast transition between an early Einstein-de Sitter CDM-like era and a later $\Lambda$CDM-like phase. If the transition is fast enough, these models may exhibit satisfactory structure formation and CMB fluctuations. To consider a concrete case, we introduce a toy UDM model and show that it can predict CMB and matter power spectra that are in agreement with observations for a wide range of parameter values.Comment: 30 pages, 15 figures, JHEP3 style, typos corrected; it matches the published versio

The Intentional Use of Service Recovery Strategies to Influence Consumer Emotion, Cognition and Behaviour

Service recovery strategies have been identified as a critical factor in the success of. service organizations. This study develops a conceptual frame work to investigate how specific service recovery strategies influence the emotional, cognitive and negative behavioural responses of . consumers., as well as how emotion and cognition influence negative behavior. Understanding the impact of specific service recovery strategies will allow service providers' to more deliberately and intentionally engage in strategies that result in positive organizational outcomes. This study was conducted using a 2 x 2 between-subjects quasi-experimental design. The results suggest that service recovery has a significant impact on emotion, cognition and negative behavior. Similarly, satisfaction, negative emotion and positive emotion all influence negative behavior but distributive justice has no effect

Temporal, Situational and Interactional Features of Women’s Violent Conflicts

This article examines contextual and situational influences on the processural development of women\u27s violent conflicts. Through close analysis of 3 women\u27s accounts of their disputes and associated violent behaviours, we provide a rich description of how such events evolved over time and how the interviewees managed this process. Drawing upon both criminological and feminist theories, our analysis highlights existing gaps in the literature, providing an exploratory discussion of the interaction of gender with situational elements and the production of assaultive events

FCNC Top Quark Decays in Extra Dimensions

The flavor changing neutral top quark decay t -> c X is computed, where X is a neutral standard model particle, in a extended model with a single extra dimension. The cases for the photon, X= \gamma$, and a Standard Model Higgs boson, X = H, are analyzed in detail in a non-linear$R_\xi gauge. We find that the branching ratios can be enhanced by the dynamics originated in the extra dimension. In the limit where 1/R >> ->, we have found Br(t -> c \gamma) \simeq 10^{-10} for 1/R = 0.5 TeV. For the decay t -> c H, we have found Br(t -> cH) \simeq 10^{-10} for a low Higgs mass value. The branching ratios go to zero when 1/R -> \infty.Comment: Accepted to be published in the Europ. Phys. Jour. C; 16 pages, 2 figure

Reliability of the tuck jump injury risk screening assessment in elite male youth soccer players

Altered neuromuscular control has been suggested as a mechanism for injury in soccer players. Ligamentous injuries most often occur during dynamic movements, such as decelerations from jump-landing maneuvers where high risk movement patterns are present. The assessment of kinematic variables during jump-landing tasks as part of a pre-participation screen is useful in the identification of injury risk. An example of a field-based screening tool is the repeated tuck jump assessment. The purpose of this study was to analyze the within-subject variation of the tuck jump screening assessment in elite male youth soccer players. 25 pre and 25 post-peak height velocity (PHV) elite male youth soccer players from the academy of a professional English soccer club completed the assessment. A test, re-test design was used to explore the within-subject inter-session reliability. Technique was graded retrospectively against the 10-point criteria set out in the screening protocol using two-dimensional video cameras. The typical error range reported for tuck jump total score (0.90 – 1.01 in pre and post-PHV players respectively) was considered acceptable. When each criteria was analyzed individually, Kappa coefficient determined that knee valgus was the only criterion to reach substantial agreement across the two test sessions for both groups. The results of this study suggest that although tuck jump total score may be reliably assessed in elite male youth soccer players, caution should be applied in solely interpreting the composite score due to the high within-subject variation in a number of the individual criteria. Knee valgus may be reliably used to screen elite youth male soccer players for this plyometric technique error and for test, re-test comparison

E-retailing ethics in Egypt and its effect on customer repurchase intention

The theoretical understanding of online shopping behaviour has received much attention. Less focus has been given to the formation of the ethical issues that result from online shopper interactions with e-retailers. The vast majority of earlier research on this area is conceptual in nature and limited in scope by focusing on consumers’ privacy issues. Therefore, the purpose of this paper is to propose a theoretical model explaining what factors contribute to online retailing ethics and its effect on customer repurchase intention. The data were analysed using variance-based structural equation modelling, employing partial least squares regression. Findings indicate that the five factors of the online retailing ethics (security, privacy, non- deception, fulfilment/reliability, and corporate social responsibility) are strongly predictive of online consumers’ repurchase intention. The results offer important implications for e-retailers and are likely to stimulate further research in the area of e-ethics from the consumers’ perspective