460 research outputs found
Heat fluxes between the Guadalquivir river and the Gulf of Cádiz Continental Shelf
An 18-year time series of daily sea surface temperature of Gulf of Cadiz and an 18-month time series of temperature collected in the vicinity of the Guadalquivir estuary mouth have been analyzed to investigate the heat exchange between the estuary and the adjacent continental shelf. The first time identifies a continental shelf area where seasonal thermal oscillation signal (amplitudes and phase) changes abruptly.
In order to explain this anomaly, the second data set allows a description of thermal fluctuations in a wide range of frequencies and an estimation of the upstream heat budget of the Guadalquivir estuary. Results show that high frequency thermal signal, diurnal and semidiurnal, and water flux signal through Guadalquivir mouth, mainly semidiurnal, apparently interact randomly to give a small exchange of thermal energy at high frequency. There is no trace, at the estuary's mouth, of daily heat exchanges with intertidal mudflats probably because it tends to cancel on daily time scales. Results also show that fluctuations of estimated air-sea fluxes force fluctuations of temperature in a quite homogeneous estuarine, with a delay of 20 days. The along-channel thermal energy gradient reaches magnitudes of 300-400 J m-4 near the mouth during the summer and winter and drives the estuary-shelf exchange of thermal energy at seasonal scale. Particularly, the thermal heat imported by the estuary from the shelf area during late fall-winter-early spring of 2008/2009 is balanced by the thermal heat that the estuary exports to the shelf area during late spring-summer of 2008. In summary, Guadalquivir river removes/imports excess of thermal energy towards/from the continental shelf seasonally, as a mechanism to accommodate excess of heat from one side respect to the other side.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech. Autoridad Portuaria de Sevilla (APS
Bi-objective optimization of a multihead weighing process
[EN] A multihead weighing process is a packaging technology that can be of strategic importance to a company, as it can be a key to competitive advantage in the modern food industry. The improvement in the process quality and sensory quality of food packaged in a multihead weighing process investigated in this paper is relevant to industrial engineering. A bi-objective ad hoc algorithm based on explicit enumeration for the packaging processes in multihead weighers with an unequal supply of the product to the weighing hoppers is developed. The algorithm uses an a priori strategy to generate Pareto-optimal solutions and select a subset of hoppers from the set of available ones in each packing operation. The relative importance of both aforementioned objectives is dynamically managed and adjusted. The numerical experiments are provided to illustrate the performance of the proposed algorithm and find the optimum operational conditions for the process.García-Díaz, JC.; Pulido-Rojano, A.; Giner-Bosch, V. (2017). Bi-objective optimization of a multihead weighing process. European J of Industrial Engineering. 11(3):403-423. doi:10.1504/EJIE.2017.084882S40342311
Bicriteria food packaging process optimization in double-layered upright and diagonal multihead weighers
[EN] Double-layered multihead weighing machines contain twice the number of hoppers as present in a simple machine with the same number of heads, which enables additional objective optimization possibilities considering the increased number of combinations among hoppers. This research study deals with bicriteria optimization for double-layered upright and diagonal machines using brute force as the optimization criteria. One of the optimization objectives is related to the target weight; the target weight must be at least and as close as possible to the weight to pack. Furthermore, this study also aims to minimize the time for which a certain portion of a product remains in the hopper while waiting to be selected for package formation. This time is known as priority and is measured based on the number of iterations or the number of packages produced by the machine while the hopper waits to be discharged. For these purposes, Different strategies were tested for both machines, which simultaneously optimize the target weight and the priority of the hoppers, showing the reduction of the extraction of the process in addition to reducing the costs of excess product and its reprocessing.We express our gratitude for the support from Universidad Simon Bolivar, Colombia, and Universitat Politecnica de Valencia.Garcia-Jimenez, R.; García-Díaz, JC.; Pulido-Rojano, AD. (2023). Bicriteria food packaging process optimization in double-layered upright and diagonal multihead weighers. Journal of Computational and Applied Mathematics. 428:1-10. https://doi.org/10.1016/j.cam.2023.11516811042
Demographic limitation processes
20 páginas, 2 figuras, 1 tabla, 3 cuadros.-- Editor: Valladares, F.[ES]: Procesos de limitación demográfica. Este capítulo ofrece una revisión de los factores que afectan a la regeneración natural de la vegetación, considerando la serie de etapas demográficas que determinan la dinámica demográfica de una pobla- ción. Son muy escasos los estudios disponibles que analizan toda la serie de eventos concatenados entre la producción de flores y frutos y el establecimiento exitoso de una planta adulta reproductiva. También son escasos los trabajos que permiten establecer los efectos aplazados que tienen las interacciones con animales a lo largo del ciclo de regeneración. La aproximación que proponemos cuantifica las pérdidas de propágulos en cada etapa demográfica e identifica “cuellos de botella” del reclutamiento que pue- den colapsar la regeneración natural de una especie. Revisamos una serie de casos de estudio que ilustran diversos procesos de limitación demográfica. El uso de técnicas explícitamente demográficas es fundamental para comprender la evolución de las especies forestales Mediterráneas y para diseñar actuaciones de preservación de sus poblaciones y de su extraordinaria diversidad.[EN]: We review the main factors
influencing recruitment limitation in Mediterranean woody species by considering the
sequential stages that determine the demographic cycle. Very few studies examine the
whole set of demographic stages, from flower production to the successful establishment
of adult reproductive plants, and their influence on recruitment. There are also few studies
exploring the delayed effects of animal interactions throughout the regeneration
cycle, but the information on stage-specific effects is more detailed. We propose an
approach that quantifies the propagule losses at each sequential demographic stage and
identifies demographic bottlenecks that might collapse population growth. We review a
series of case studies illustrating different limitation processes. The use of explicit demographic
techniques is central to understand the evolution of Mediterranean woody species
and to design sound, ecologically-based, conservation plans to preserve their extraordinary
diversity.Juan Arroyo agradece la financiación otorgada a los proyectos 4474-91
(National Geographic Society), PB 91-0894, PB95-0551, 1FD97-0743-CO3-03, PB98-1144,
BOS200307924-CO2-01 (MECD, MCyT). Los trabajos de Pedro Jordano han sido financiados con proyectos MECD y MCyT (1FD97-0743-CO3-01, PB
96-0857, BOS2000-1366-C02-01 y REN2003-00273), así como la Junta de Andalucía (PAI).
Juan Luis García-Castaño estuvo financiado durante su período pre-doctoral con una beca
FPU, AP96-27318040. El trabajo de Fernando Pulido ha sido parcialmente financiado por una
beca FPI de la Junta de Extremadura y los proyectos regional IPR-0A050 y estatal BOS2002-
12222-E del Ministerio de Ciencia y Tecnología. Los trabajos de Patricio García-Fayos han
sido financiados con proyectos MCyT (1FD97-0551), de la Generalitat Valenciana (02-046)
y de la Institució Alfons el Magnánim (02-046)Peer reviewe
Packaging Process Optimization in MultiheadWeighers with Double-Layered Upright and Diagonal Systems
[EN] In multihead weighers, packaging processes seek to find the best combination of passage hoppers whose product content provides a total package weight as close as possible to its (nominal) label weight. The weighing hoppers arranged in these machines dispense the product quantity that each package contains through computer algorithms designed and executed for this purpose. For its part, in the packaging process for double-layered multihead weighers, all hoppers are arranged in two levels. The first layer comprises a group of weighing hoppers, and the second comprises a set of booster hoppers placed uprightly or diagonally to each weighing hopper based on design of the machine. In both processes, the initial machine configuration is the same; however, the hopper selection algorithm works differently. This paper proposes a new packaging process optimization algorithm for double-layer upright and diagonal machines, wherein the hopper subset combined has previously been defined, and the packaging weight is expressed as actual values. As part of its validation, product filling strategies were implemented for weighing hoppers to assess the algorithm in different scenarios. Results from the process performance metrics prove that the new algorithm improves processes by reducing variability. In addition, results reveal that some machine configurations were also able to improve their operation.We express our gratitude for the support from Universidad Simon Bolivar, and Universitat Politecnica de Valencia.Garcia-Jimenez, R.; García-Díaz, JC.; Pulido-Rojano, ADJ. (2021). Packaging Process Optimization in MultiheadWeighers with
Double-Layered Upright and Diagonal Systems. Mathematics. 9(9):1-20. https://doi.org/10.3390/math9091039S1209
Métodos quimiométricos para el cálculo de triglicéridos mediante ácidos grasos en aceites de oliva vírgenes españoles
The level of acceptation of "1, 3-random 2-random" pattern of acyl groups distribution in virgin olive oil glycerides has been analysed in 36 samples, by comparing the values of triacylglycerols obtained by HPLC with those reported by the cited theory. Hotelling's T2, Principal Components and Canonical Correlation Analysis have been used to study both data sets. The normality of the data distributions, the intra-and intergroup correlations of the triacylglycerols were studied before these multivariate statistical algorithms were applied.
An alternative way of estimating triacylglycerols from only total fatty acids has also been studied. A Stepwise Multiple Regression procedure has been employed, and Multiple R coefficients fluctuate between 0,75 and 0,94 except for the variable SOS.Se ha analizado el nivel de aceptación del patrón "1, 3-al azar 2-al azar" de la distribución de los grupos acil dentro de los glicéridos del aceite de oliva. Para ello se han comparado los valores de los triglicéridos obtenidos por HPLC con los deducidos mediante esa teoría con 36 muestras de aceites de oliva españoles. Hotelling's T2, Componentes Principales y Correlación Canónica han sido los procedimientos estadísticos usados para estudiar ambos grupos de datos. Previamente se habían analizado la normalidad de la distribución de los datos y las correlaciones intra-intergrupo de triglicéridos.
Se propone un camino alternativo para estimar algunos triglicéridos mediante los valores de los ácidos grasos. Se ha empleado un procedimiento de regresión múltiple por pasos, obteniéndose valores de R que fluctúan entre 0,75 y 0,94 excepto para el triglicérido SOS
Monitoring and control of the multihead weighing process through a modified control chart
Modified control charts are used to monitor and control manufacturing processes which are considered to be six-sigma processes. The use of these charts is based on the idea that the cost of identifying and correcting special causes is much higher than the cost of off-target products. Therefore, the process mean is essentially acceptable as long as it is anywhere within the specification limits. These concepts are applied to the packaging process in multihead weighers. The weight of the packed product, seen as the quality characteristic to be monitored, must be as close to a specified target weight as possible and comply with applicable regulations. The packaging process was previously optimized and improved using a packaging strategy, which was evaluated through a proposed packing algorithm. In this way, a set of numerical experiments were conducted to examine the solutions generated, which were subsequently monitored.Los gráficos de control modificados se utilizan para el seguimiento y control de procesos de fabricación que son considerados como procesos seis-sigma. El uso de estos gráficos se basa en la idea de que el costo de identificar y corregir causas especiales de variación es mucho más alto que el costo de productos alejados de su valor nominal. Por lo tanto, la media del proceso es esencialmente aceptable siempre que esté dentro de los límites de especificación. Estos conceptos han sido aplicados al proceso de envasado en pesadoras multicabezal. El peso del producto envasado, visto como la característica de calidad a ser monitoreada, debe ser lo más cercano posible a un peso objetivo y cumplir con la normativa. El proceso ha sido previamente optimizado y mejorado mediante una estrategia de envasado, la cual es evaluada a través de un algoritmo de envasado. De esta manera, un conjunto de experimentos numéricos fueron realizados para examinar las soluciones generadas, las cuales son posteriormente monitoreadas
Parameterization, Analysis, and Risk Management in a Comprehensive Management System with Emphasis on Energy and Performance (ISO 50001: 2018)
[EN] The future of business development relies on the effective management of risks, opportunities, and energy and water resources. Here, we evaluate the application of best practices to identify, analyze, address, monitor, and control risks and opportunities (R/O) according to ISO 31000 and 50000. Furthermore, we shed light on tools, templates, ISO guides, and international documents that contribute to classifying, identifying, formulating control, and managing R/O parameterization in a comprehensive management system model, namely CMS QHSE3+, which consists of quality (Q), health and safety (HS), environmental management (E), energy efficiency (E2), and other risk components (+) that include comprehensive biosecurity and biosafety. By focusing on the deployment of R/O-based thinking (ROBT) at strategic and operational levels, we show vulnerability reduction in CMS QHSE3+ by managing energy, efficiency, and sustainability.We express our gratitude for the support from Cajacopi Atlantico, QUARA Technology, ASTEQ Technology, Universidad Simon Bolivar, Universitat Politecnica de Valencia and to all the personnel and companies who offered us their contributions and their valuable points of view.Poveda-Orjuela, PP.; García-Díaz, JC.; Pulido-Rojano, A.; Cañón-Zabala, G. (2020). Parameterization, Analysis, and Risk Management in a Comprehensive Management System with Emphasis on Energy and Performance (ISO 50001: 2018). Energies. 13(21):1-44. https://doi.org/10.3390/en13215579S1441321SDBS Business Demography Indicatorshttps://stats.oecd.org/index.aspx?queryid=70734The World Economy on a Tightrope. 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Estrategias de optimización Bi-Objetivo para el proceso de pesaje multicabezal
[EN] Multihead weighing processes are considered an important strategy in packaging companies. Multihead weighers are used for
dosing a wide range of products, from granules to large products. The packaging process consists of choosing a subset of
hoppers in the multihead weigher to form a product package. This paper proposes a set of filling strategies of hoppers to
reduce the variability in the weight of the produced packages. The strategies are evaluated through a bi-objective optimization
approach which aims to minimize the absolute difference between the target weight and the actual weight of the packages,
while trying to maximize the selection of those hoppers with more time in the packaging system. In the bi-objective approach,
the considered objectives are dynamically adjusted and managed in each packaging operation. In addition, the mathematical
model and the packing algorithm are developed and presented. The results of the process performance parameters are
obtained and analyzed to show the effectiveness of the proposed strategies. Also, conditions of minimum variability are
identified and those can be used by the packaging industry where multihead weighers are used.[ES] Los procesos de pesaje multicabezal son actualmente considerados una estrategia importante en empresas de envasado.
Maquinas pesadoras multicabezal son utilizadas para la dosificación de amplia gama de productos, desde granulados a
productos de gran tamaño. El proceso de envasado consiste en la selección de un subconjunto de tolvas en la pesadora
multicabezal para formar un paquete de producto. La presente investigación propone un conjunto de estrategias de llenado de
tolvas para reducir la variabilidad en el peso de los paquetes producidos. Las estrategias son evaluadas mediante un enfoque
de optimización bi-objeivo que busca minimizar la diferencia absoluta entre el peso objetivo y el peso real de los paquetes, al
tiempo que intenta maximizar la selección de aquellas tolvas con mayor tiempo en el sistema de envasado. En el enfoque biobjetivo, los objetivos considerados son dinámicamente ajustados y gestionados en cada operación de envasado. Además, el
modelo matemático que representa nuestro problema y el algoritmo de envasado son desarrollados y presentados. Los
resultados de los parámetros de rendimiento del proceso son obtenidos y analizados como una medida de la efectividad de las
estrategias propuestas. Asimismo, las condiciones de mínima variabilidad son identificadas para motivar su uso en la
industria de envasado de producto en donde se utilicen máquinas de pesaje multicabezal.Pulido-Rojano, AD.; García-Díaz, JC. (2019). Estrategias de optimización Bi-Objetivo para el proceso de pesaje multicabezal. Investigación Operacional. 40(3):362-373. http://hdl.handle.net/10251/157765S36237340
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