A discrete MMAP for analysing the behaviour of a multi-state complex dynamic system subject to multiple events.

A complex multi-state system subject to different types of failures, repairable and/or nonrepairable, external shocks and preventive maintenance is modelled by considering a discrete Markovian arrival process with marked arrivals (D-MMAP). The internal performance of the system is composed of several degradation states partitioned into minor and major damage states according to the risk of failure. Random external events can produce failures throughout the system. If an external shock occurs, there may be an aggravation of the internal degradation, cumulative external damage or extreme external failure. The internal performance and the cumulative external damage are observed by random inspection. If major degradation is observed, the unit goes to the repair facility for preventive maintenance. If a repairable failure occurs then the system goes to corrective repair with different time distributions depending on the failure state. Time distributions for corrective repair and preventive maintenance depend on the failure state. Rewards and costs depending on the state at which the device failed or was inspected are introduced. The system is modelled and several measures of interest are built into transient and stationary regimes. A preventive maintenance policy is shown to determine the effectiveness of preventive maintenance and the optimum state of internal and cumulative external damage at which preventive maintenance should be taken into account. A numerical example is presented, revealing the efficacy of the model. Correlations between the numbers of different events over time and in non-overlapping intervals are calculated. The results are expressed in algorithmic-matrix form and are implemented computationally with Matlab.Junta de Andalucía, Spain, under the grant FQM307Ministerio de Economía y Competitividad, España, MTM2017-88708-PEuropean Regional Development Fund (ERDF

Universal prototype for adapting from conventional centrifugal fertilizer to variable-rate spreader

Congreso Agroingeniería 2015. Orihuela (Alicante). 1 a 3 de junio de 2015La Agricultura de Precisión constituye un nuevo paradigma en la agricultura de hoy. A objetivos como el aumento de la productividad o de la eficiencia económica, se les unen otros en auge como el respeto medioambiental y un riguroso control en la seguridad alimentaria. En general las técnicas de agricultura de precisión requieren de un mejor conocimiento de las necesidades del cultivo y del suelo, y también del empleo de la maquinaria más adecuada que tenga en cuenta la variabilidad espacial y temporal en las necesidades de los cultivos. En este contexto, este estudio tiene como objetivo principal, el diseño, desarrollo y evaluación de una plataforma universal para controlar una abonadora centrífuga convencional mediante un monitor comercial inicialmente diseñado para el control de barras de pulverización de productos líquidos, lo que permite la adaptación dinámica de la cantidad de fertilizante sólido según las necesidades reales del cultivo. Para el desarrollo del sistema de control fue necesario realizar una caracterización de la abonadora mediante pruebas de calibración del sistema dosificador. También se han desarrollado los distintos módulos de hardware (módulo para el control de los discos, interacción con el sistema de control de líquidos comercial, etc.) necesarios para automatizar las acciones que se realizan durante el funcionamiento de la máquina. Para la gestión del sistema se utiliza la plataforma de hardware libre de bajo coste Arduino que resulta fácilmente adaptable para otras abonadoras, desarrollando un software capaz de gestionar el resto de componentes. Finalmente se monta todo el conjunto a bordo del tractor y se realizan las pruebas de funcionamiento. Se comprobó que el sistema trabaja correctamente, con una respuesta adecuada, consiguiendo automatizar el proceso de variar la dosis durante la marcha de forma eficaz.Como se observa en estos primeros resultados, la utilización de este equipo como elemento importante en una aplicación variable de insumos, puede suponer una reducción económica y del impacto medioambiental de la operación, además de permitir una distribución mas racional del nitrógeno u otros fertilizantes en campo, algo sin duda de especial relevancia en sistemas modernos de producción.Precision Agriculture represents a new paradigm in modern agriculture. To objective such as increasing productivity and economic efficiency, are joined other arising objective as the environmental concern. Precision agriculture techniques require a better understanding of crop and soil needs, and the use of precise machinery that take into account the spatial-temporal variability across fields. In these terms, the goal of this study was the design, development and evaluation of a universal platform to control a conventional disc fertilizer spreader, and thus able to manage the amount of fertilizer on the go. A specific on-field calibration was necessary to determine the spreader settings for a given type of fertilizer. The components of the hardware modules (control system of disks, interaction with sections control system, etc.) capable of automating actions performed in operation of the spreader were developed. The control system was developed based on an open-source and low-cost microcontroller-board (Arduino), which could be adapted easily to other spreader model, and a firmware capable to control the hardware components. Once installed on-board, field tests were provided to investigate the proper functioning and response time (approx. 1 sec) of the control system and achieve automate the process of varying the fertilizer dose on the go. As noted these preliminary results, the utilization of this prototype as an essential part of a variable input application may found an economic reduction in fertilizer operation and environmental impact, and allows the control of nitrogen or other fertilizer in fields, techniques that definitely significant in modern agriculture production systems

Determination of Arsenic, Mercury and Barium in herbarium mount paper using dynamic ultrasound-assisted extraction prior to atomic fluorescence and absorption spectrometry

A dynamic ultrasound-assisted extraction method using Atomic Absorption and Atomic Flourescence spectrometers as detectors was developed to analyse mercury, arsenic and barium from herbarium mount paper originating from the herbarium collection of the National Museum of Wales. The variables influencing extraction were optimised by a multivariate approach. The optimal conditions were found to be 1% HNO3 extractant solution used at a flow rate of 1 mL min-1. The duty cycle and amplitude of the ultrasonic probe was found to be 50% in both cases with an ultrasound power of 400 W. The optimal distance between the probe and the top face of the extraction chamber was found to be 0 cm. Under these conditions the time required for complete extraction of the three analytes was 25 min. Cold vapour and hydride generation coupled to atomic fluorescence spectrometry was utilized to determine mercury and arsenic, respectively. The chemical and instrumental conditions were optimized to provide detection limits of 0.01ng g-1 and 1.25 ng g-1 for mercury and arsenic, respectively. Barium was determined by graphite-furnace atomic absorption spectrometry, with a detection limit of 25 ng g-1. By using 0.5 g of sample, the concentrations of the target analytes varied for the different types of paper and ranged between 0.4–2.55 µg g-1 for Ba, 0.035–10.47 µg g-1 for As and 0.0046–2.37 µg g-1 for Hg

A Bayesian state-space size-structured population dynamics model for northern hake.

In Fisheries research bayesian state-space models have been proved to be very useful because of their capacity to include new data while measuring the uncertainty associated to biological and physical processes. The ECOKNOWS (Effective use of ecosystem and biological knowledge in Fisheries) project proposes to use bayesian analysis in a general population dynamics model GPDM as a powerful tool to include biological and physical information in management strategies. Results of a preliminary Bayesian model adapting this model to northern hake population dynamics are presented here. The model intends to reproduce as far as possible the structure and main assumptions of the current ICES model. Actually there are some parameters with convergence problems but we are developing a new version considering informative priors for the biological processes which are supposed to ameliorate the estimations.Versión de auto

A bayesian model for European hake with priors based on life history invariants.

European hake is a main target fish for the fleet operating in Atlantic waters, although there are many biological unknowns that compromise the quality of the current assessment and scientific advice. Growth, natural mortality and reproduction are main biological processes required to develop population dynamic models for assessment purposes. Currently, the parameters defining these processes such Von Bertalanffy asymptotic length, M, L 50% of maturity or Beverton-Holt steepness are estimated outside the model and set as constants. Population dynamic bayesian models provide a suitable platform to develop solutions to this kind of problems since Bayesian models allow using additional knowledge from similar species in the form of the priors. Informative priors for biological key parameters have been developed based on available data for Northern hake combined with information from other hake species all over the world. This information is analyzed on the light of ecological theory for life history invariants (LHI) to produce the required priors. LHI figures are relatively constant among similar species. Information from other hakes may help to fill the gap in assessment and management of European hake. The pros and cons of using these informative priors to improve hake assessment are finally discussed

Efecto de la densidad de ungulados silvestres sobre los invertebrados en un ecosistema Mediterráneo

[EN]: Effect of wild ungulate density on invertebrates in a Mediterranean ecosystem.— In recent decades, the abundance and distribution of certain big game species, particularly red deer (Cervus elaphus) and wild boar (Sus scrofa), have increased in south central Spain as a result of hunting management strategies. The high density of these ungulate species may affect the abundance of epigeous invertebrates. We tested the relationships between big game abundance and biodiversity, taxon richness, the biomass of invertebrates and their frequency on nine hunting estates and in comparison to ungulate exclusion areas. Ungulate exclusion itself affected invertebrate richness, since lower values were found in the open plots, whereas the highest differences in invertebrate diversity between fenced and open plots was found in areas with high wild boar density. Where wild boar densities were high, the number of invertebrates decreased, while where they were low, red deer had a positive effect on invertebrate abundance. Fenced plots thus seemed to provide refuge for invertebrates, particularly where wild boar were abundant. This study supports the idea that the structure of fauna communities is damaged by high density populations of ungulates, probably due to decreased food availability owing to overgrazing, modified conditions of ecological microniches and direct predation. However, the effects depended on the group of invertebrates, since saprophytic species could benefit from high ungulate abundance. Our findings reflect the need to control ungulate population density under Mediterranean conditions in south-western Europe and to implement ungulate exclusion plots.[ES]: En las últimas décadas, la abundancia y distribución de determinadas especies de caza mayor, especialmente el ciervo rojo (Cervus elaphus) y el jabalí (Sus scrofa), han aumentado en la zona centromeridional de España como resultado de las estrategias de gestión cinegética. La alta densidad de estas especies de ungulados puede afectar a la abundancia de los invertebrados epigeos. Estudiamos la relación entre la abundancia de las especies de caza mayor y la biodiversidad, la riqueza de taxones, la biomasa de invertebrados y su frecuencia en nueve fincas de caza, y se comparó con las zonas de exclusión de ungulados. De por sí, la exclusión de ungulados afectó a la riqueza de invertebrados, ya que se encontraron valores más bajos en las parcelas abiertas, mientras que las mayores diferencias en la diversidad de invertebrados entre parcelas abiertas y cercadas se encontraron en zonas con una alta densidad de jabalíes. Donde la densidad de jabalíes era alta, el número de invertebrados disminuyó, mientras que donde era baja, el ciervo rojo tuvo un efecto positivo en la abundancia de invertebrados. Así, las parcelas cercadas parecían ofrecer refugio a los invertebrados, sobre todo donde los jabalíes eran abundantes. Este estudio apoya la idea de que las poblaciones con una alta densidad de ungulados perjudican a la estructura de las comunidades faunísticas, probablemente debido a la disminución de la disponibilidad de alimentos como consecuencia del sobrepastoreo, la modificación de las condiciones de los micronichos ecológicos y la depredación directa. Sin embargo, los efectos dependieron del grupo de invertebrados, ya que las especies saprofitas podrían beneficiarse de la alta abundancia de ungulados. Nuestros resultados reflejan la necesidad de controlar la densidad de las poblaciones de ungulados en condiciones mediterráneas en el suroeste de Europa y de establecer parcelas de exclusión de ungulados.We are grateful to the estate keepers for their hospitality and assistance in the field work, and to the Andalucía Autonomous Government’s Environmental Council for financing this work via a project to improve the habitat of the black vulture in Córdoba province, thanks to which we have been able to carry out this work.Peer Reviewe

Determination of field capacity and yield mapping in olive harvesting using remote data acquisition

Sensors, communication systems and geo-reference units are required to achieve an optimized management of agricultural inputs with respect to the economic and environmental aspects of olive groves. In this study, three commercial olive harvesters were tracked in Spain and Chile using remote and autonomous equipment to determine their time efficiency and field capacity. An experimental methodology for analyzing the data to determine the field capacity and efficiency is proposed, which, along with a conventional methodology, was used to analyze the data to determine field capacity and efficiency. The results of both methodologies are compared to validate the suitability of the experimental methodology. Furthermore, a yield monitor was developed and evaluate using one of the tested olive harvesters. The results show that yield monitoring of olives is possible, but further research is needed to archieve a more reliable methodology

On the probable composition of ‘Jamaican stone’ aphrodisiac

A dangerous aphrodisiac, commonly known as ‘Jamaican stone’, banned by the U.S. Food and Drug Administration, has been studied by vibrational spectroscopy in order to solve the controversy on its composition. The results of the ATR-FTIR analysis revealed the presence of the a-pyrone ring, which is characteristic of bufadienolides from toad venom and bulbs of squill (Drimia maritima (L.) Stearn). This conclusion was reached after a comparative study with the spectra for phytochemicals derived from gambir and cat''s claw, two Uncaria species also preconized as aphrodisiacs and deemed as possible constituents of the ‘stone’. Owing to their physiologic similarities to digoxin, bufadienolides have been shown to produce a toxic profile similar to that of digoxin, although the lack one of the side chains found on digoxin should allow the use of hemodialysis to treat ‘Jamaican stone’ overdose

Effect of wild ungulate density on invertebrates in a Mediterranean ecosystem

Efecto de la densidad de ungulados silvestres sobre los invertebrados en un ecosistema Mediterráneo En las últimas décadas, la abundancia y distribución de determinadas especies de caza mayor, especialmente el ciervo rojo (Cervus elaphus) y el jabalí (Sus scrofa), han aumentado en la zona centromeridional de España como resultado de las estrategias de gestión cinegética. La alta densidad de estas especies de ungulados puede afectar a la abundancia de los invertebrados epigeos. Estudiamos la relación entre la abundancia de las especies de caza mayor y la biodiversidad, la riqueza de taxones, la biomasa de invertebrados y su frecuencia en nueve fincas de caza, y se comparó con las zonas de exclusión de ungulados. De por sí, la exclusión de ungulados afectó a la riqueza de invertebrados, ya que se encontraron valores más bajos en las parcelas abiertas, mientras que las mayores diferencias en la diversidad de invertebrados entre parcelas abiertas y cercadas se encontraron en zonas con una alta densidad de jabalíes. Donde la densidad de jabalíes era alta, el número de invertebrados disminuyó, mientras que donde era baja, el ciervo rojo tuvo un efecto positivo en la abundancia de invertebrados. Así, las parcelas cercadas parecían ofrecer refugio a los invertebrados, sobre todo donde los jabalíes eran abundantes. Este estudio apoya la idea de que las poblaciones con una alta densidad de ungulados perjudican a la estructura de las comunidades faunísticas, probablemente debido a la disminución de la disponibilidad de alimentos como consecuencia del sobrepastoreo, la modificación de las condiciones de los micronichos ecológicos y la depredación directa. Sin embargo, los efectos dependieron del grupo de invertebrados, ya que las especies saprofitas podrían beneficiarse de la alta abundancia de ungulados. Nuestros resultados reflejan la necesidad de controlar la densidad de las poblaciones de ungulados en condiciones mediterráneas en el suroeste de Europa y de establecer parcelas de exclusión de ungulados.In recent decades, the abundance and distribution of certain big game species, particularly red deer (Cervus elaphus) and wild boar (Sus scrofa), have increased in south central Spain as a result of hunting management strategies. The high density of these ungulate species may affect the abundance of epigeous invertebrates. We tested the relationships between big game abundance and biodiversity, taxon richness, the biomass of invertebrates and their frequency on nine hunting estates and in comparison to ungulate exclusion areas. Ungulate exclusion itself affected invertebrate richness, since lower values were found in the open plots, whereas the highest differences in invertebrate diversity between fenced and open plots was found in areas with high wild boar density. Where wild boar densities were high, the number of invertebrates decreased, while where they were low, red deer had a positive effect on invertebrate abundance. Fenced plots thus seemed to provide refuge for invertebrates, particularly where wild boar were abundant. This study supports the idea that the structure of fauna communities is damaged by high density populations of ungulates, probably due to decreased food availability owing to overgrazing, modified conditions of ecological microniches and direct predation. However, the effects depended on the group of invertebrates, since saprophytic species could benefit from high ungulate abundance. Our findings reflect the need to control ungulate population density under Mediterranean conditions in south–western Europe and to implement ungulate exclusion plots.Efecto de la densidad de ungulados silvestres sobre los invertebrados en un ecosistema Mediterráneo En las últimas décadas, la abundancia y distribución de determinadas especies de caza mayor, especialmente el ciervo rojo (Cervus elaphus) y el jabalí (Sus scrofa), han aumentado en la zona centromeridional de España como resultado de las estrategias de gestión cinegética. La alta densidad de estas especies de ungulados puede afectar a la abundancia de los invertebrados epigeos. Estudiamos la relación entre la abundancia de las especies de caza mayor y la biodiversidad, la riqueza de taxones, la biomasa de invertebrados y su frecuencia en nueve fincas de caza, y se comparó con las zonas de exclusión de ungulados. De por sí, la exclusión de ungulados afectó a la riqueza de invertebrados, ya que se encontraron valores más bajos en las parcelas abiertas, mientras que las mayores diferencias en la diversidad de invertebrados entre parcelas abiertas y cercadas se encontraron en zonas con una alta densidad de jabalíes. Donde la densidad de jabalíes era alta, el número de invertebrados disminuyó, mientras que donde era baja, el ciervo rojo tuvo un efecto positivo en la abundancia de invertebrados. Así, las parcelas cercadas parecían ofrecer refugio a los invertebrados, sobre todo donde los jabalíes eran abundantes. Este estudio apoya la idea de que las poblaciones con una alta densidad de ungulados perjudican a la estructura de las comunidades faunísticas, probablemente debido a la disminución de la disponibilidad de alimentos como consecuencia del sobrepastoreo, la modificación de las condiciones de los micronichos ecológicos y la depredación directa. Sin embargo, los efectos dependieron del grupo de invertebrados, ya que las especies saprofitas podrían beneficiarse de la alta abundancia de ungulados. Nuestros resultados reflejan la necesidad de controlar la densidad de las poblaciones de ungulados en condiciones mediterráneas en el suroeste de Europa y de establecer parcelas de exclusión de ungulados