231 research outputs found
Existence and uniqueness of solutions to the Bellman equation in the unbounded case
We study the problem of the existence and uniqueness of solutions to the Bellman equation in the presence of unbounded returns. We introduce a new approach based both on consideration of a metric on the space of all continuous functions over the state space, and on the application of some metric fixed point theorems. With appropriate conditions we prove uniqueness of solutions with respect to the whole space of continuous functions. Furthermore, the paper provides new sufficient conditions for the existence of solutions that can be applied to fairly general models. It is also proven that the fixed point coincides with the value function and that it can be approached by successive iterations of the Bellman operator.The research of J. P. Rincón-Zapatero was supported by Project VA108/01 of Junta de Castilla
y León and Project BFM2002–00425 (FEDER) of Ministerio de Ciencia y Tecnología, Spain. C. Rodríguez-Palmero gratefully acknowledges financial support from Junta de Castilla y León,
Project VA31/01.Publicad
Prevalencia de algunas enfermedades infecciosas en bovinos de resguardos indígenas del Cauca, Colombia, 2017
La zona del Cauca posee resguardos indígenas que han presentado diferentes problemáticas asociadas a la lucha armada en Colombia, lo que ha limitado que las entidades puedan realizar programas de control de enfermedades bovinas. Por lo anterior, el objetivo de este trabajo fue determinar la prevalencia de algunas enfermedades infecciosas de carácter reproductivo en el ganado bovino de tres resguardos indígenas del Cauca, 2017. Se recolectaron muestras sanguíneas de 30 vacas para determinar la prevalencia de Neospora caninum, Brucella abortus, diarrea viral bovina (DVB), rinotraqueitis infecciosa bovina (IBR) y Leptospira sp. serovares Hardjo prajitno, bovis y Pomona. Las pruebas se realizaron por ELISA, rosa de bengala y microaglutinación. Mediante el software R se realizó un análisis descriptivo y se determinaron las prevalencias para cada enfermedad, se estimaron las co-infecciones y se realizó un modelo de regresión logística para determinar el efecto del hato, resguardo, componente racial, grupo etario, número de animales y tamaño del hato sobre la positividad a las enfermedades. Se encontró una prevalencia del 36% para N. caninum, 60% DVB, 30% IBR, 0% B. abortus, Leptospira spp. serovares Harjo prajitno 26%, Hardjo bovis 12% y Pomona 10%. De acuerdo al análisis de riesgo, la seropositividad para DVB e IBR estuvo asociada con el resguardo donde habitaban los animales, en este caso Tacueyó tuvo más riesgo y estuvo directamente relacionado con el área de los hatos, entre mayor área más animales fueron positivos. En general se encontró que la situación de la zona es similar a la de otros sitios de Colombia
VariaMos: an extensible tool for engineering (dynamic) product lines
International audienceThis paper presents the new release of VariaMos, a Java-based tool for defining variability modeling languages, modeling (dynamic) product lines and cyber-physical self-adaptive systems, and supporting automated verification, analysis, configuration and simulation of these models. In particular, we describe the characteristics of this new version regarding its first release: (1) the capability to create languages for modeling systems with variability, even with different views; (2) the capability to use the created language to model (dynamic) product lines; (3) the capability to analyze and configure these models according to the changing context and requirements; and (4) the capability to execute them over several simulation scenarios. Finally, we show how to use VariaMos with an example, and we compare it with other tools found in the literature
Numerical simulation and experiments of the multiphase flow in a liquid-liquid cylindrical cyclone separator
A Liquid-Liquid Cylindrical Cyclone separator (LLCC) is a device used in the petroleum industry to separate the oil-water mixture obtained from the well. The use of this device has not been widespread due to the lack of tools for predicting its separation capability. This paper presents a numerical and experimental study of the fluid dynamic performance of this type of cylindrical cyclone separators. The use of numerical simulations would reduce the time and cost necessary to obtain information for predicting the behavior of the equipment. The objective of this study is to determine if CFD (Computational Fluid Dynamics) techniques are able to reproduce the behavior of a LLCC separator. The CFD software examined was ANSYS-CFX 5.6TM and numerical simulations were carried out using the dispersed model with oil as the dispersed phase. The oil and water mixture entering the separator is divided due to centrifugal and buoyancy forces in an upper (oil rich) exit and a bottom (water rich) exit. The separation capability is determined as the maximum amount of water removed from the mixture with the minimum amount of oil content in the water rich exit. The experiments were conducted in a transparent LLCC separator that allows the visualization of the mixture and the measurement of the oil content. Experiments were conducted for three variables: mixture velocity and water content at the entrance, and the split ratio. The split ratio is defined as the bottom exit flow rate divided by the water flow rate at the entrance. The results showed that CFD tools are able to reproduce the oil content obtained from the experiments for all analyzed conditions. Additionally, the mixture distribution images from numerical and experimental data showed good agreement. This study confirms the capacity of CFD tools for the multiphase flow analysis of LLCC separators
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Comparison of five different RNA sources to examine the lactating bovine mammary gland transcriptome using RNA-Sequencing.
The objective of this study was to examine five different sources of RNA, namely mammary gland tissue (MGT), milk somatic cells (SC), laser microdissected mammary epithelial cells (LCMEC), milk fat globules (MFG) and antibody-captured milk mammary epithelial cells (mMEC) to analyze the bovine mammary gland transcriptome using RNA-Sequencing. Our results provide a comparison between different sampling methods (invasive and non-invasive) to define the transcriptome of mammary gland tissue and milk cells. This information will be of value to investigators in choosing the most appropriate sampling method for different research applications to study specific physiological states during lactation. One of the simplest procedures to study the transcriptome associated with milk appears to be the isolation of total RNA directly from SC or MFG released into milk during lactation. Our results indicate that the SC and MFG transcriptome are representative of MGT and LCMEC and can be used as effective and alternative samples to study mammary gland expression without the need to perform a tissue biopsy
Numerical simulation and experiments of the multiphase flow in a liquid-liquid cylindrical cyclone separator
A Liquid-Liquid Cylindrical Cyclone separator (LLCC) is a device used in the petroleum industry to separate the oil-water mixture obtained from the well. The use of this device has not been widespread due to the lack of tools for predicting its separation capability. This paper presents a numerical and experimental study of the fluid dynamic performance of this type of cylindrical cyclone separators. The use of numerical simulations would reduce the time and cost necessary to obtain information for predicting the behavior of the equipment. The objective of this study is to determine if CFD (Computational Fluid Dynamics) techniques are able to reproduce the behavior of a LLCC separator. The CFD software examined was ANSYS-CFX 5.6TM and numerical simulations were carried out using the dispersed model with oil as the dispersed phase. The oil and water mixture entering the separator is divided due to centrifugal and buoyancy forces in an upper (oil rich) exit and a bottom (water rich) exit. The separation capability is determined as the maximum amount of water removed from the mixture with the minimum amount of oil content in the water rich exit. The experiments were conducted in a transparent LLCC separator that allows the visualization of the mixture and the measurement of the oil content. Experiments were conducted for three variables: mixture velocity and water content at the entrance, and the split ratio. The split ratio is defined as the bottom exit flow rate divided by the water flow rate at the entrance. The results showed that CFD tools are able to reproduce the oil content obtained from the experiments for all analyzed conditions. Additionally, the mixture distribution images from numerical and experimental data showed good agreement. This study confirms the capacity of CFD tools for the multiphase flow analysis of LLCC separators
Evaluación agronómica de nueve variedades arbustivas de habichuela, phaseolus vulgaris, en el municipio de arbeláez, cundinamarca
Nueve variedades arbustivas de habichuela (Phaseolus vulgaris) se compararon contra una variedad testigo voluble (Blue Lake) por variables fisiológicas, fenológicas y de rendimiento en el municipio de Arbeláez (Cundinamarca) a una altura de 1500 m.s.n.m. Las variedades arbustivas no presentaron diferencias estadísticas en altura de planta y fueron coincidentes en el número de días hasta la floración, fructificación e iniciaciónde la cosecha. Todas las variedades evaluadas fueron estadísticamente iguales para el rendimiento de vaina comercial, lo cual resalta el buen comportamiento de los materiales arbustivos en las condiciones de estudio.Nine bush bean varieties (Phaseolus vulgaris) were tested against a regional bean variety (Blue Lake), for some physiological, phenological and yield variables in Arbeláez (Cundinamarca) at an altitude of 1500 m. Bush bean varieties did not show differences in plant height and phenological variables. Al! bush bean varieties had comparable commercial pod yields, which emphasizes the good performance of these materials under the conditions of this study
Middle Eocene Rhodoliths from Tropical and Mid-Latitude Regions
During the greenhouse conditions prevailing in the early–middle Eocene, larger benthic
foraminifers (LBF) spread out on carbonate platforms worldwide while rhodolith beds were scarcely
represented. This reduction in rhodolith beds coincided with a relative decrease in coralline algal
diversity and with a drastic decline of coral reef abundance. Middle Eocene rhodoliths from two
tropical (San Jacinto Fold Belt in northern Colombia and Bahoruco Peninsula in the Dominican
Republic) and two mid-latitude (Salinas Menores Ravine and Sierra del Zacatín in Southern Spain)
localities were studied. Rhodolith rudstones in the tropical areas accumulated on relatively deep
(several tens of meters) platform environments and were also redeposited in deeper settings downslope.
In Salinas Menores, rhodoliths are dispersed in planktic foraminifer-rich marls. Miliolids are common
in the infilling of constructional voids in these rhodoliths, indicating that they originally grew in
shallow-water inner-shelf settings and afterwards they were transported to deeper environments.
In Sierra del Zacatín, rhodoliths are scarce and coralline algae mainly occur as crusts attached to
and intergrowing with corals. Here, LBF dominated shallow-water carbonate platforms. In terms
of taxonomic composition, coralline algae of the order Hapalidiales are the most abundant in the
study areas, followed by Sporolithales. The order Corallinales is poorly represented except in Salinas
Menores, where it is relatively abundant and diverse. The impact of high temperatures due to high
levels of atmospheric CO2 during the Eocene and widespread oligotrophic conditions, which favored
formation of LBF-rich lithofacies, might account for the low abundance of rhodolith beds at mid and
high latitudes. In contrast, the more productive equatorial regions would have favored the formation
of rhodolith beds.This research was funded by Research Group RNM-190 of the Junta de Andalucía (JA and JCB),
MINECO/FEDER-UE project CGL2015-65404-R and by the Consolidated Research Group IT930-16 of the Basque
Government (VP and XOE)
Nuevos datos cronoestratigráficos de la Fm. Marismas (Bajo Guadalquivir)
La Formación Marismas forma la parte superior del relleno sedimentario del sector SW de la cuenca del Guadalquivir. Los datos previos sobre el sondeo Lebrija, indicaban que la parte más alta de esta formación tenía edades de hasta 9.6 kyr BP y en la parte inferior eran cercanas o fuera del rango del radiocarbono, pero posterior a la reversión
Brunhes-Matuyama. En este trabajo se aportan 17 nuevas dataciones realizadas mediante racemización de aminoácidos en valvas de ostrácodos en este mismo sondeo, con el fin de
completar la cronología y el modelo de edad de la parte superior e inferior de la Fm Marismas. El resultado indica que el tramo situado por debajo del metro 56, arroja edades
que oscilan entre 164685±14110 y 202830±30255, que se correlacionan con los estadios isotópicos marinos MIS 6-7 del Pleistoceno medio, edad sensiblemente más baja a las inferidas para esta formación en otros puntos de la Cuenca del bajo GuadalquivirEste trabajo se ha realizado dentro del proyecto Guadaltyc (Impacto del clima y la tectónica en el registro sedimentario de la Cuenca del Guadalquivir, (CGL2012-30875).Peer Reviewe
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