682 research outputs found

    Simulación de procesos con controladores lógico-programables (PLC’s)

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    La realización de prácticas en el laboratorio de control de procesos presenta como mayor dificultad el coste asociado al funcionamiento del proceso, debido al consumo de reactivos, de energía o a la generación de residuos. Por tanto se propone trabajar con un proceso simulado en un controlador lógico- programable o PLC, con lo que se realiza una práctica de bajo coste y más cercana a la realidad que la pura simulación numérica

    Asymmetric 1,3-dipolar cycloaddition reactions between enals and nitrones catalysed by half-sandwich rhodium or iridium diphosphane complexes

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    The aqua complexes ¿(¿5-C5Me5)M¿PP*)¿H2O)]¿SbF6]2 (M = Rh, Ir; PP* = chiral diphosphane) have been tested as catalysts for the asymmetric 1,3-dipolar cycloaddition of nitrones to a,ß-unsaturated aldehydes. Quantitative conversions with very high regioselectivity, perfect endo selectivity and excellent enantioselectivity (up to 99% ee) were achieved. The stereochemical outcome was analyzed on the basis of the stereoelectronic properties of the intermediate enal complexes of the formula ¿(¿5-C5Me5)M¿PP*)¿enal)]¿SbF6]2

    A framework for financial botnet analysis

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    Financial botnets, those specifically aimed at carrying out financial fraud, represent a well-known threat for banking institutions all around the globe. Unfortunately, these malicious networks are responsible for huge economic losses or for conducting money laundering operations. Contrary to DDoS and spam malware, the stealthy nature of financial botnets requires new techniques and novel research in order to detect, analyze and even to take them down. This paper presents a work-in-progress research aimed at creating a system able to mitigate the financial botnet problem. The proposed system is based on a novel architecture that has been validated by one of the biggest savings banks in Spain. Based on previous experiences with two of the proposed architecture building blocks -the Dorothy framework and a blacklist-based IP reputation system-, we show that it is feasible to map financial botnet networks and to provide a non-deterministic score to its associated zombies. The proposed architecture also promotes intelligence information sharing with involved parties such as law enforcement authorities, ISPs and financial institutions. Our belief is that these functionalities will prove very useful to fight financial cybercrime

    Predator arrival elicits differential dispersal, change in age structure and reproductive performance in a prey population

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    Acknowledgements We thank everyone monitoring colonies over the years, in particular Carles Domingo from the Ebro Delta NP Staff, Ràpita, Castelló and the Tarragona Port Authorities and José Manuel Igual from the Group of Ecology and Animal Demography. We also thank the editorial board and the reviewers for their constructive comments. RESET (ref.CGL2017-85210-P), FPU (ref. FPU2012-000869), IBISES (ref. CGL2013-42203-R) and MINOW (ref. H2020- 634495). ASA and MG are supported by a postdoctoral contract co-funded by the Regional Government of the Balearic Islands and the European Social Fund (ref. PD/003/2016 and PD/023/2015).Peer reviewedPublisher PD

    Aproximacions demogràfiques per avaluar l’estat de conservació de la baldriga cendrosa Calonectris diomedea i la baldriga balear Puffinus mauretanicus: Demographic approaches for assessing the conservation status of Scopoli’s Shearwater Calonectris diomedea and the Balearic Shearwater Puffinus mauretanicus

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    In the north-western Mediterranean there are two breeding species of procellariforms from the Procellariidae family: Scopoli’s shearwater Calonectris diomedea and the Balearic shearwater Puffinus mauretanicus. Long-term monitoring carried out in a number of breeding colonies provides enough data to be able to assess the conservation status of both species using demographic approaches that estimate parameters such as survival, recruitment and fertility. This type of approach is recommended because it provides a reliable conservation diagnosis and knowledge of the processes that determine variations in population dynamics. Both species were found to have critically low adult survival rates, unexpected in such long-lived species, which makes these populations unviable under current conditions. This agrees with previous available information on incidental bycatch on fishing gears, and confirms that this threat, together with predation by terrestrial carnivores are of critical concern for the conservation of the populations. The fact that some of the breeding colonies did not show a declining trend indicates that several compensatory mechanisms, such as an immigration rescue effect, may be acting at local level. Nevertheless, all the evidence gathered to date suggests that these compensatory mechanisms are not permanent and that if no action is taken these populations could become extinct. In the case of Scopolis’ shearwater, the global population is much more abundant, so there may be time for mitigation actions to be undertaken. Given the size of the breeding population of Balearic shearwaters, we recommend urgent measures be carried out to reduce adult mortality in this endemic species to prevent its extinction

    Estimating the cumulative effects of the nature-based tourism in a coastal dolphin population from southern Kenya

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    Due to the growth of nature-based tourism worldwide, behavioural studies are needed to assess the impact of this industry on wildlife populations and understand their short-term effect. Tourism impact on dolphin populations remain poorly documented in developing countries. This study investigates the effects of nature-based tourism on the behaviour of the Indo-Pacific bottlenose dolphins (Tursiops aduncus) in southern Kenya. We used Markov chain models to estimate transition probabilities between behavioural states in the presence and absence of tourist boats, and assess the overall behavioural budgets. Based on these data and the tourism intensity in the area, we quantified the potential tourist boat disturbance over the period 2006-2013. Our results demonstrated that tourist boat interactions affected dolphins' behavioural budgets, with a significant decrease in the overall amount of time travelling and an increase in diving. The average duration of travelling and resting decreased significantly in the presence of boats. Although the cumulative tourism exposure was not significant for the dolphin population at their current levels, these impacts should be taken into consideration with the potential tourism growth in the area. This is particularly important if tourism reaches periods of high intensity, as we have shown that these periods could have a significant impact for the species, particularly where home-range and core areas are highly overlap by this activity. Understanding the effect of human disturbance variations from previous years may help to predict the consequences on dolphin populations, towards achieving a more ecological and economic sustainability of the activity

    Use of the Richtmyer-Meshkov Instability to Infer Yield Stress at High-Energy Densities

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    We use the Richtmyer-Meshkov instability (RMI) at a metal-gas interface to infer the metal’s yield stress (Y) under shock loading and release. We first model how Y stabilizes the RMI using hydrodynamics simulations with a perfectly plastic constitutive relation for copper (Cu). The model is then tested with molecular dynamics (MD) of crystalline Cu by comparing the inferred Y from RMI simulations with direct stress-strain calculations, both with MD at the same conditions. Finally, new RMI experiments with solid Cu validate our simulation-based model and infer Y~0.47 GPa for a 36 GPa shock

    New Alloying Systems for Sintered Steels: Critical Aspects of Sintering Behavior

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    Oxygen-sensitive alloying elements such as Mn, Si, and Cr have a high potential for improving the properties of low alloyed sintered steels while reducing the alloying cost. However, it is necessary to find a way for avoiding, or at least minimizing, the oxidation of these elements especially during the early stages of the sintering cycle. In this study Mn, Si, and Cr were introduced in the form of a master alloy powder designed to be mixed with the iron base powder and provide the final composition of the steel during the sintering process. The reduction/oxidation phenomena taking place during the heating stage were studied by thermogravimetry, dilatometry, and mass spectroscopy, using either reducing (H2) or inert (Ar) atmospheres. The results show how the difference in chemical activity between base iron powder and master alloy causes the so called "internal-getter" effect, by which the reduction of less stable iron oxides leads to oxidation of the elements with higher affinity for oxygen. This effect can be somehow minimized when sintering in H2, since the iron oxides are reduced at lower temperatures at which the reactivity of the elements in the master alloy is lower. However, H2 concentration in the processing atmosphere needs to be carefully adapted to the specific composition of the materials being processed in order to minimize decarburization by methane formation during sintering.Höganäs AB Sweden, financial support provided through the Höganäs Chair IVPublicad
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