225 research outputs found

    ILS-ESP: An efficient, simple, and parameter-free algorithm for solving the permutation flow-shop problem

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    From a managerial point of view, the more e cient, simple, and parameter-free (ESP) an algorithm is, the more likely it will be used in practice for solving real-life problems. Following this principle, an ESP algorithm for solving the Permutation Flowshop Sequencing Problem (PFSP) is proposed in this article. Using an Iterated Local Search (ILS) framework, the so-called ILS-ESP algorithm is able to compete in performance with other well-known ILS-based approaches, which are considered among the most e cient algorithms for the PFSP. However, while other similar approaches still employ several parameters that can a ect their performance if not properly chosen, our algorithm does not require any particular fine-tuning process since it uses basic ‘common sense’ rules for the local search, perturbation, and acceptance criterion stages of the ILS metaheuristic. Our approach defines a new operator for the ILS perturbation process, a new acceptance criterion based on extremely simple and transparent rules, and a biased randomization process of the initial solution to randomly generate di erent alternative initial solutions of similar quality -which is attained by applying a biased randomization to a classical PFSP heuristic. This diversification of the initial solution aims at avoiding poorly designed starting points and, thus, allows the methodology to take advantage of current trends in parallel and distributed computing. A set of extensive tests, based on literature benchmarks, has been carried out in order to validate our algorithm and compare it against other approaches. These tests show that our parameter-free algorithm is able to compete with state-of-the-art metaheuristics for the PFSP. Also, the experiments show that, when using parallel computing, it is possible to improve the top ILS-based metaheuristic by just incorporating to it our biased randomization process with a high-quality pseudo-random number generator.Preprin

    Drugs and Biodiversity Loss: Narcotraffic-Linked Landscape Change in Guatemala

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    Characteristic of the Anthropocene, human impacts have resulted in worldwide losses in forested land cover, which can directly and indirectly drive biodiversity loss. The global illicit drug trade is one source of deforestation directly implicated with habitat loss in Central America, typically for drug trafficking and livestock production for money laundering. Given reports of deforestation in Central America linked to narcotraffic, we explored vegetation changes within Guatemala’s highly biodiverse Maya Biosphere Reserve by examining trends suggestive of deforestation in a protected area. As such, we collected satellite-derived data in the form of enhanced vegetation index (EVI), as well as history of burned areas, published human-“footprint” data, official population density, and artificial light activity in Laguna del Tigre National Park from 2002 to 2020 for descriptive analysis. We found consistent reductions in EVI and trends of anomalous losses of vegetation despite a baseline accounting for variation within the park. Analyses revealed weak correlations (R2 ≤ 0.26) between EVI losses and official sources of anthropogenic data, which may be attributable to the data’s limited spatial and temporal resolution. Alarmingly, simple analyses identified vegetation losses within a protected area, thus emphasizing the need for additional monitoring and science-based, but interdisciplinary policies to protect this biodiversity hotspot

    Medida de autocontrol motor en tiradores de esgrima mediante el Tapping Test

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    El Tapping Test es una prueba neurológica habitual en las evaluaciones de los equipos nacionales de Cuba. Nuestro objetivo fue medir el autocontrol motor con esta prueba y su respuesta psicofisiológica en deportistas de la selección nacional de esgrima de Cuba. Comparando dos versiones del Tapping Test: modo 1 (habitual de lápiz-papel) y modo 2 (versión propuesta ejecutando acción técnica con el arma). Fueron 12 participantes (Medad = 22.19 años, DE = 3.50 años). Se utilizó un equipo de registro psicofisiológico inalámbrico (Biofeedback 2000). Los resultados, indican un autocontrol motor, siendo el modo 1 significativo F(1,10) = 44.29, p < .001; ya que la cantidad de toques o golpes fueron coherentes de acuerdo al ritmo de ejecución. El modo 2 tuvo una motilidad o aceleración significativa en las diferentes fases de la prueba F(1.58,15.8) = 8.14, p = .006, además mostró un mayor nivel de activación psicofisiológica. Este grupo de esgrimistas de alto nivel a pesar del incremento en la activación mostraron un autocontrol motor, ya que controlaron su movimiento de acuerdo al ritmo que se pedía (modo 1).The Tapping Test is a common neurological means of evaluating Cuba's national teams. Our objective was to assess self-control of motor abilities and the athletes' psychophysiological response by comparing two versions of the tapping test: mode 1 (normal pencil and paper) and mode 2 (technical action with the épée). The participants were made up of 12 athletes from the Cuban National Fencing Team (Mage = 22.19 years, SD = 3.50 years). We used wireless psychophysiological recording equipment (Biofeedback 2000). The results show self-control of motor abilities, mode 1 being significant F(1,10) = 44.29, p < .001 as the number of touches or hits was consistent with the execution rate. Mode 2 showed a motility or significant acceleration in the different phases of the test F(1.586, 15.85) = 8146, p = .006, plus a higher level of psychophysiological activation. This high-ranking group of fencers demonstrated self-control of their motor abilities despite increased activation, controlling their movements to match the requested pace (mode 1)

    Modeling and simulation of chloride diffusion in concrete with recycled aggregates

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    The concrete along with steel, are the responsibility structural material required to respond to mechanical stresses; specifically, the tensile stresses are borne by the steel, and it is this material that involvement of durability can lose their resilience. Corrosion of steel is one of the main causes of this affectation in the steel, and this is caused by the entry of chloride ions in the called phenomenon diffusion. This phenomenon is governed by the diffusion equations of the Fick's first and second law [1]; for these, there are several models that describe the behavior of chloride diffusion in conventional concrete, but nevertheless, not in the recycled concrete. In this paper, are used as basis, the models of Janzhuang Xiao et al. [2] and Long-Yuang Li et al. [3] to model and simulate the phenomenon of chloride diffusion in concrete with recycled aggregates; for which it has been used a five-phase model for the aggregate: old and new Interfacial Transition Zones (ITZ), new and old mortar, and original aggregate. Furthermore, in this model were considered as variables the Thickness of the Interfacial Transition Zone (TITZ), the rate of old mortar adhered, the volume fraction of the aggregates and the continuity of the ITZ. The model considered, was composed by aPeer ReviewedPostprint (published version

    Influencia de la fertilización nitrogenada sobre las concentraciones de K+, Mg2+ y Ca2+ y sus bioindicadores en raíces y hojas de plantas de judía

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    The pyruvate kinase (PK) and ATPase activities taking part in nitrogen (N) assimilation is essential for the growth and development of plants. Studies on the kinetics of these enzymes reveal that its activities are dependent of the cofactors K+, Ca2+, and Mg2+. Therefore, the objective of the present work was to determine the effect of different doses of N on enzymatic activities of ATPase and PK as potentials biochemical indicators of the levels of K+, Mg2+, and Ca2+ in the roots and leaves of green bean plants. The N was applied to the nutrient solution as NH4NO3 at the following rates: 1.5, 3.0, 6.0, 12.0, 18.0, and 24.0 mM of N. These results indicate that deficient conditions of N (N1 and N2) were characterized by the lowest accumulation of K+, Mg2+ and Ca2+ in both total and soluble forms, and also minimum activities of PK and ATPase induced by K+, Mg2+ and Ca2+, with respect to the activity of basal PK and ATPase; this could mean near optimum conditions for these cations. On the contrary, high-N treatments (N4, N5 and N6) were characterized by presenting decreasing concentrations of total and soluble K+, Mg2+ and Ca2+ in roots and leaves of green bean plants; however, the activities of PK and ATPase induced with K+, Mg2+ and Ca2+ were increased reaching their maximum activity with respect to basal PK and ATPase, both enzymes reflecting the level of cations in roots and leaves, hence being considered as good physiological bioindicators of these cations.Las actividades piruvato kinasa (PK) y ATPasa participan en la asimilación de nitrógeno (N), la cual es esencial para el crecimiento y desarrollo de las plantas. Estudios sobre cinéticas de estas enzimas revelan que sus actividades son dependientes de los cofactores K+, Ca2+ y Mg2+. Por lo tanto, el objetivo del presente trabajo fue determinar el efecto de diferentes dosis de N sobre las actividades de la ATPasa y PK como posibles bioindicadores de los niveles de K+, Mg2+ y Ca2+ en raíces y hojas de plantas de judía (Phaseolus vulgaris L. cv. Strike). Se aplicó N a la solución nutritiva como NH4NO3 en las siguientes dosis: N1=1,5 mM, N2=3,0 mM, N3=6,0 mM, N4=12,0 mM, N5=18,0 mM y N6=24,0 mM. Los resultados indican que bajo condiciones deficientes de N (N1 y N2), las plantas presentaron menor acumulación de K+, Mg2+ y Ca2+ en su forma total y soluble, así como mínimas actividades PK y ATPasa inducidas por K+, Mg2+ y Ca2+ respecto a la actividad PK y ATPasa basal; lo cual indica condiciones cercanas a las óptimas de estos cationes. Por el contrario, en los tratamientos elevados de N (N4, N5 y N6) las plantas presentaron concentraciones decrecientes de K+, Mg2+ y Ca2+ total y soluble tanto en raíces como en hojas; sin embargo, las actividades PK y ATPasa inducidas con K+, Mg2+ y Ca2+ se incrementaron alcanzando sus máximas actividades con respecto a la PK y ATPasa basal, lo que indica una mayor necesidad fisiológica de estos cationes en los tratamientos elevados de N. Finalmente, la actividad ATPasa basal y la inducida con K+, Mg2+ y Ca2+ se comportaron de forma similar a la actividad PK, lo que refleja el nivel de cationes en raíces y en hojas, por lo que se consideran buenos bioindicadores fisiológicos de estos cationes

    Cambios en el perfil bioquímico hepático de alpacas positivas a huevos de Fasciola hepática

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    The aim of this study was to determine changes in the liver biochemical profile in alpacas with presence of F. hepatica eggs. We used serum and feces samples of 35 male alpaca between 2-5 years old, 18 were positives and 17 were negatives in coproparasitologic analysis for F. hepatica eggs. Differences are showed (p&lt;0.05) in the values of ALT, GGT and direct bilirubin between positives y negatives animals. We concluded that there is relationship between presence of F. hepatica eggs and high levels in the liver biochemical profile, maybe due to alterations in the hepatic parenchyma by chronic infection in alpacas.El objetivo del presente estudio fue determinar cambios en el perfil bioquímico hepático en alpacas con presencia de huevos de F. hepatica en heces. Se utilizaron muestras de suero y heces de 35 alpacas machos de entre 2 y 5 años de edad, de los cuales 18 fueron positivos y 17 negativos al examen coproparasitológico (sedimentación) para identificación de huevos de F. hepática. Se observó diferencia significativa (p&lt;0.05) entre los valores de ALT, GGT y bilirrubina directa entre los animales positivos y negativos. Concluimos que la presencia de huevos de Fasciola hepatica guarda relación con la elevación de algunos parámetros del perfil hepática posiblemente por alguna alteración en el parénquima producto de una infección crónica en alpacas

    Understanding ozone generation in electrochemical cells at mild pHs

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    In this work, the production of ozone at mild pH conditions using a commercial electrochemical PEM cell CONDIAPURE Ⓡ is evaluated, at once a phenomenological model is proposed to understand the basis of the processes that occur inside the cell. At these pH conditions, the production of ozone can be explained from the oxidation of water, while the decomposition of ozone is found to be extremely important to explain the global experimental behavior observed. Not only is this decomposition a chemical but also an electrochemically assisted process which, in turn, can be related to the production of other oxidants in the cell which interact with ozone behaving as predators. The model formulated explains and satisfactorily reproduces the influence of the operation mode, the current intensity applied and presence and destruction of organics, with regression coefficients (r2) ranging from 0.88 to 0.99, helping to understand how the production of ozone should be promoted during electrochemical processes

    Is ozone production able to explain the good performance of CabECO® technology in wastewater treatment?

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    This work intends to go a step further in the application of electrochemical technology to produce ozone, by evaluating the production of ozone with a commercial cell registered as CabECO®, which has been previously used to disinfect heavily polluted water in a successful manner, with a view to ascertaining whether this success may be related to the production of ozone. The CabECO® cell is a PEM electrolyzer; that is to say, one in which anode and cathode are connected through a PEM membrane. Since ozone production on the electrolyte is important and depends on the composition of the liquid, attention must be paid to the electrochemical production of scavengers. Dosing of oxygen as microbubbles has a very positive effect on the production of ozone, while temperature regulation is as well considerably important, as the increase in temperature generated by ohmic losses can lead to important decreases in the efficiency of ozone electrogeneration. Rates within the range 0.06–0.60 mg O3 min−1 are observed; this means that the maximum current efficiency reached is as high as 6.11% (considering oxygen as raw matter). These results are extremely promising as compared with other references in the literature, at once they also indicate there is room for further improvements and a long way to prevent the effect of scavengers and increase the efficiency of the process

    Perfil Bioquímico Sanguíneo Hepático del Cocodrilo de Tumbes (Crocodylus acutus) Criado en Cautiverio

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    The liver blood chemical profile of the American crocodile (Crocodylus acutus) raised in captivity in the northern region of Peru was determined. Sixty crocodiles were sampled from a population of 255 animals belonging to the Zoocriadero del Centro de Acuicultura La Tuna Carranza, part of the National Fisheries Development Fund (FONDEPES) located in the region of Tumbes, Peru. The animals were classified as young (n=24), subadults (n=27) and adults (n=9). A blood sample (6 ml) was taken from each animal by puncturing the post-occipital venous sinus while animals were under physical restraint. Serum was separated by centrifugation and concentration of each enzyme was measured by spectrophotometry. Variables studied were alanine aminotransferase (ALT), aspartate amino transferase (AST), alkaline phosphatase (ALP), total bilirubin, direct bilirubin, indirect bilirubin, total protein and albumin. Statistical difference (p&lt;0.05) was found between age groups in ALT, FA, direct bilirubin, and total protein. All values with the exception of albumin showed high biological differences with those reported by the International Species Information System.Se determinó el perfil bioquímico hepático del cocodrilo de Tumbes (Crocodylus acutus) criado en cautiverio en el norte del Perú. Se trabajó con 60 cocodrilos de una población de 255 animales del Zoocriadero del Centro de Acuicultura La Tuna Carranza, del Fondo Nacional de Desarrollo Pesquero (FONDEPES), ubicado en la región de Tumbes, Perú. De estos, 24 eran juveniles, 27 subadultos y 9 adultos. Se extrajo 6 ml de sangre entera sin anticoagulante por punción del seno venoso post-occipital manipulando al animal mediante contención física. Se separó el suero mediante centrifugación y las enzimas se analizaron mediante espectrofotometría. Las variables en estudio fueron alanina aminotransferasa (ALT), aspartato amino transferasa (AST), fosfatasa alcalina (FA), bilirrubina total, bilirrubina directa, bilirrubina indirecta, proteínas totales y albúmina. Se encontró diferencia estadística (p&lt;0.05) en relación a los grupos etarios con respecto a la ALT, FA, bilirrubina directa y proteínas totales. Todos los valores con excepción de la albúmina tuvieron marcadas diferencias biológicas con respecto a valores publicados por el International Species Information System

    Scale-up in PEM electro-ozonizers for the degradation of organics

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    This work focuses on the scale-up of electro-ozonizers by evaluating the production of ozone and the degradation of clopyralid synthetic wastes using three commercial PEM electrolyzers. The mechanical concept of the three cells is similar: a single compartment cell equipped with a MEA (consisting of a polymer exchange membrane and two pressed diamond coatings electrodes), powered with monopolar electric connection and where water flows on the surface of the electrodes, although the main electrolyte is the Nafion proton exchange membrane. However, their size and recommended operating conditions are not as similar, and their comparison becomes a good scaleup case study. The CabECO® cell consists of 2 MEAs with a total surface area of 24 cm2, a maximum operating current density of 2. 0A. The Mikrozom® cell consists of only one MEA with a net surface electrodic area of 112 mm2 and a maximum operation current density of 1.0 A. Finally, the CONDIAPURE® cell consists of a single MEA with a total surface area of 146 cm2 and a maximum operation current density of 10.0 A. The performance under mild and extreme operating conditions was compared and the results show that, although the cell concept is similar, the results obtained differ very significantly. The three PEM electrolyzers tested can produce ozone efficiently and mineralize completely clopyralid. The only intermediates measured come from the cathodic hydrodechlorination of clopyralid and oxidative intermediates were only detected at trace concentrations. CabECO® cell demonstrates an outstanding performance with very high current efficiencies in the production of ozone. However, the highest mineralization efficiencies are obtained with the Microzon®, which, although it is the PEM electrolyzer with the smallest active area, is the most efficient because can reach high ozone concentrations and achieve the best clopyralid mineralization. Efficiencies as high as 0.47 mg O3 Wh−1 can be obtained with this cell. Slightly lower values are reached by the CabECO® cell (0.38 mg O3 Wh−1). Enlarging electrode surface area does not seem to be a good strategy from the viewpoint of efficiency and it seems to promote side reactions that compete with ozone production and with the degradation of organics. This means that stacking rather than electrode enlarging should be the strategy more advisable for scaling up the electro-ozonation technology.Este trabajo se centra en la ampliación de los electro-ozonizadores mediante la evaluación de la producción de ozono y la degradación de los desechos sintéticos de clopiralida utilizando tres electrolizadores PEM comerciales. El concepto mecánico de las tres celdas es similar: una celda de un solo compartimiento equipada con un MEA (compuesto por una membrana de intercambio de polímero y dos electrodos de revestimiento de diamante prensado), alimentada con conexión eléctrica monopolar y donde el agua fluye en la superficie de los electrodos, aunque el electrolito principal es la membrana de intercambio de protones Nafion. Sin embargo, su tamaño y las condiciones operativas recomendadas no son tan similares, y su comparación se convierte en un buen caso de estudio de ampliación. La celda CabECO® consta de 2 MEA con una superficie total de 24 cm 2, una densidad de corriente operativa máxima de 2. 0A. La celda Mikrozom® consta de un solo MEA con un área superficial neta de electrodos de 112 mm 2 y una densidad de corriente máxima de operación de 1,0 A. Finalmente, la celda CONDIAPURE® consta de un solo MEA con un área superficial total de 146 cm 2y una densidad de corriente máxima de operación de 10.0 A. Se comparó el desempeño en condiciones de operación suaves y extremas y los resultados muestran que, aunque el concepto de celda es similar, los resultados obtenidos difieren muy significativamente. Los tres electrolizadores PEM probados pueden producir ozono de manera eficiente y mineralizar completamente la clopiralida. Los únicos intermedios medidos provienen de la hidrodecloración catódica de clopiralida y los intermedios oxidativos solo se detectaron en concentraciones mínimas. La celda CabECO® demuestra un desempeño sobresaliente con eficiencias de corriente muy altas en la producción de ozono. Sin embargo, las mayores eficiencias de mineralización se obtienen con el Microzon® que, si bien es el electrolizador PEM con menor área activa, es el más eficiente porque puede alcanzar altas concentraciones de ozono y lograr la mejor mineralización de clopiralida. Eficiencias de hasta 0,47 mg OCon esta celda se pueden obtener 3 Wh −1 . La celda CabECO® alcanza valores ligeramente inferiores (0,38 mg O 3 Wh −1 ). Ampliar el área de la superficie del electrodo no parece ser una buena estrategia desde el punto de vista de la eficiencia y parece promover reacciones secundarias que compiten con la producción de ozono y con la degradación de compuestos orgánicos. Esto significa que el apilamiento en lugar de la ampliación de electrodos debería ser la estrategia más recomendable para escalar la tecnología de electro-ozonización
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