Análisis estructural de la cubierta principal de un buque de apoyo a plataformas con una grúa sobre orugas

Support vessels for platforms in the oil industry have operation versatility and capacity for structural modification. This article presents a proposal for the installation of a crawler crane on the main deck of a platform support vessel, which will carry out offshore maintenance operations. This proposal includes the results of the structural analysis of the main deck, considering its reinforcement with two NVA36 beams. This structural analysis incorporates the integrity of the main deck, taking into account the crane and loads through finite element method (FEM) models. The obtained results show that the main deck requires the proposed reinforcement to decrease the maximum stresses of von Mises up to 218.71 MPa for the structure of the main deck and 201.67 MPa for the reinforcement beams. These maximum stresses do not exceed the allowable and yield stresses of the main deck material. The reinforcement of the main deck that supports crawler crane allows safe operation of the offshore support vessel.Los buques de apoyo para plataformas de la industria petrolera tienen versatilidad de operación y capacidad de modificación estructural. Este artículo presenta una propuesta de instalación de una grúa sobre orugas sobre la cubierta principal de un buque de apoyo a plataformas petroleras, el cual realizará operaciones de mantenimiento en mar adentro. Esta propuesta incluye los resultados del análisis estructural de la cubierta principal, donde se considera el refuerzo con dos vigas NVA36. Este análisis estructural incorpora la integridad de la cubierta principal considerando la grúa y las cargas mediante modelos del método de elementos finitos (MEF). Los resultados obtenidos muestran que la cubierta principal requiere el refuerzo propuesto para disminuir las tensiones máximas de Von Mises hasta 218,71 MPa para la estructura de la cubierta principal y 201,67 MPa en las vigas de refuerzo. Estas tensiones máximas no superan las tensiones admisibles y de fluencia del material de la cubierta principal. El refuerzo de la cubierta principal que soporta la grúa sobre orugas permite la operación segura del buque de apoyo mar adentro.

Exploration of operating conditions in the direct aqueous-phase reforming of plastics

Plastic materials are employed in countless applications, resulting in a high amount of waste and the need for alternatives to landfill. In the current work, an alternative to reduce and revalorize waste plastic using direct aqueous-phase reforming (APR), a catalytic process to produce hydrogen and/or alkanes from organic molecules, is proposed with a focus on polyethylene terephthalate. The effect of operating conditions including temperature (190–235 °C), pH (3–12), and the type of metal catalyst and support, was studied. Pt catalysts yielded at 220 °C 5 mmol of H2/g of plastic in 4-hour reaction tests, which increased up to 10 mmol of H2/g of plastic for an 8-hour reaction time. Additionally, low amounts of short-chain alkanes were detected (<1.4 mmol of alkanes/g of plastic). The production of H2 was also improved by increasing reaction temperature up to 235 °C, and by using Pt-based bimetallic catalysts and supports with well-developed mesopore area. The results obtained confirm the potential of this strategy as a useful and simple way to transform plastic waste, especially PET, into H2S2018/EMT-4344, European Union’s Horizon 2020 10106435

Effect of Grazing Management on Herbage Accumulation of Lucerne-Orchard Grass Sward

Throughout most of México, lucerne (Medicago sativa) is the primary forage legume used in the dairy industry. Unfortunately, lucerne does not grow in late autumn and winter due to adverse weather. Recent studies with lucerne have suggested that the inclusion of a companion grass will invariably increase the seasonal distribution and total annual yield of swards (Laidlaw & Teuber, 2001). However the management of mixed swards containing lucerne is difficult as a grazing frequency or intensity which suits one species may be detrimental to the other. Changes in balance between grass and legume, especially in grazed swards, have been observed. In México mixtures of lucerne-orchard grass have a good persistence and productivity. However the explanation for this is unclear. This study examined the effects of different grazing management practices on lucerne-orchard grass production and seasonal distribution

Efectos del genotipo, tamaño de la camada y el sexo sobre las características de la canal y el perfil de ácidos grasos en corderos de pelo

The effect of the genotype (Pelibuey vs Katahdin), type of lambing (single vs. double) and sex (males vs. females) on the characteristics of the carcass and its cuts, in addition to the fatty acid profile of the loin were evaluated in 66 lambs slaughtered at weaning. The yield of the carcass and ribs were higher (P<0.05) in the Pelibuey breed. Slaughter weight, carcass weight and rib yield were higher (P<0.01) in single-born lambs, while the yield of shoulder and leg were lower (P<0.01) than in double-born lambs. The proportion of soft tissue of the different cuts was higher (P<0.05), but that of bone was lower (P< 0.05) in single-born lambs than in double-born lambs. Females had a higher (P<0.05) proportion of soft tissue and a lower proportion of bone (P<0.01) than males. The concentrations of C18:1n7 and C20:4n-6 were higher (P<0.05) in the Pelibuey breed than in the Katahdin breed, while the C22:5n-3 and C22:6n-3 were lower. The percentage of monounsaturated fatty acids was higher (P<0.05) in the meat of single-born lambs, while that of total polyunsaturated fatty acids and n-3 was higher (P<0.05) in double-born lambs. The characteristics of the carcass, the tissue composition of the commercial cuts and the fatty acid profile in hair sheep slaughtered at weaning varied more due to the type of lambing than due to the genotype or sex.El efecto del genotipo (Pelibuey vs Katahdin), tipo de parto (simple vs dobles) y sexo (machos vs. hembras) sobre las características de la canal y de sus cortes, además del perfil de ácidos grasos del lomo fueron evaluados en 66 corderos sacrificados al destete. El rendimiento de la canal y del costillar fue mayor (P<0.05) en la raza Pelibuey. El peso al sacrificio, peso de canal y rendimiento del costillar fue mayor (P<0.01) en crías de parto simple, mientras que el rendimiento de paleta y pierna fue menor (P< 0.01) que en crías de parto doble. La proporción del tejido blando de los diferentes cortes fue mayor (P<0.05), pero el de hueso fue menor (P< 0.05) en crías de parto simple que las de parto doble. Las hembras tuvieron mayor (P<0.05) proporción de tejido blando y menor proporción de hueso (P<0.01) que los machos. Las concentraciones de C18:1n7 y C20:4n-6 fueron mayores (P< 0.05) en la raza Pelibuey que, en la Katahdin, mientras que los C22:5n-3 y C22:6n-3 fueron menores. El porcentaje de ácidos grasos monoinsaturados fue mayor (P<0.05) en la carne de crías de partos simples, en tanto que el de los ácidos grasos poliinsaturados totales y n-3 fue mayor (P<0.05) en crías de partos dobles. Las características de la canal, la composición tisular de los cortes comerciales y el perfil de ácidos grasos en ovinos de pelo sacrificados al destete mostraron más cambios por el tipo de parto que por el genotipo o el sexo

CONTROL DE TORQUE PARA SERVOMOTORES SIN ESCOBILLAS (TORQUE CONTROL FOR BRUSHLESS SERVOMOTOR)

En años recientes, el área de la robótica ha sido el centro de atención de diversas investigaciones, debido a los beneficios prácticos que esta línea de investigación brinda a la vida cotidiana de los seres humanos. Nuevos algoritmos, sistemas, postulados y axiomas surgen todos los días para emular las capacidades que cuenta el ser humano para poder interactuar con su entorno. Una de las problemáticas que encuentran los investigadores y tecnólogos a nivel mundial referentes a línea de investigación de robótica, es la imitación de los movimientos humanos. Diversas soluciones se han propuesto desde las máquinas simples al inicio de la historia humana hasta los robots humanoides actuales. Atacando la problemática de forma abstracta es necesario contar con un dispositivo que genere un movimiento mecánico con control de posición, velocidad, aceleración y torque, similar a la función de los músculos y tendones que realiza nuestro cuerpo. Dentro de las máquinas generadoras de movimiento con que se cuenta actualmente es el motor eléctrico, entre todas sus variantes podemos encontrar a los motores especiales para posicionamiento los cuales reciben el nombre de servomotores. En general los motores eléctricos generan un movimiento rotacional por medio de la interacción de campos magnéticos, sin embargo, por sí mismo no es suficiente para cubrir los requerimientos de movimientos precisos, controlados y con fuerza constante, para lo cual es necesario adicionar a los motores eléctricos sistemas que puedan generar un control de estas variables en el comportamiento de los motores.En el presente trabajo se describe la implementación de un control digital de torque para servomotor de corriente directa sin escobillas (BLDC, por sus siglas en inglés) desde el bloque de accionamiento, la regulación de velocidad y finalmente el control de torque El control propuesto realiza una regulación del torque a través de la comparación de una señal de referencia y una medición de corriente por el sensor LTS15-NP. Para la realización de este sistema se utilizo un dispositivo FPGA Spartan 3A de la compañía Digilent para embeber la lógica de acción. En los resultados obtenidos se presentan gráficas de relación corriente eléctrica máxima y tensión suministrada, fuerza generada en la flecha del servomotor y corriente eléctrica máxima; finalmente se muestra la gráfica torque comparado con la energía circulante en los embobinados del servomotor. Con esto se comprueba de manera experimental que el comportamiento del torque es una relación proporcional de parámetros del motor y la corriente eléctrica que circula sobre las bobinas del circuito.Palabra(s) Clave: BLDC, Control Automático, Control Torque, Robótica, SoC. AbstractIn recent years, the area of robotics has been the focus of several investigations, due to the practical benefits that this line of research provides to the daily lives of human beings. New algorithms, systems, postulates and axioms emerge every day to emulate the capabilities that human beings have to interact with their environment.One of the problems encountered by researchers and technologists worldwide concerning the line of research in robotics, is the imitation of human movements. Various solutions have been proposed from simple machines at the beginning of human history to the current humanoid robots. Attacking the problem in an abstract way is necessary to have a device that generates a mechanical movement with control of position, speed, acceleration and torque, like the function of the muscles and tendons that our body performs. Among the machines that generate movement is currently the electric motor, among all its variants we can find special motors for positioning which are called servomotors. In general, electric motors generate a rotational movement by means of the interaction of magnetic fields, however, by itself it is not enough to cover the requirements of precise movements, controlled and with constant force, for which it is necessary to add to the motors electrical systems that can generate a control of these variables in the behavior of the engines.In the present work describes the implementation of a digital torque control for brushless direct current servomotor (BLDC) from the drive block, speed regulation and finally torque control a torque regulation through the comparison of a reference signal and a current measurement by the LTS15-NP sensor. For the realization of this system a Spartan 3A FPGA device from the Digilent company is used to embed the action logic. In the results obtained, the graphs of maximum electric current and voltage supply, force generated in the servomotor shaft and maximum electric current are presented; Finally, the graph of the compacted torque with the circulating energy in the servomotor windings is shown. With this, it is verified experimentally that the behavior of the torque is a proportional relation of parameters of the motor and the electric current that circulates on the coils of the circuit.Keywords: BLDC, Automatic Control, Torque Control, Robotics, SoC

Raman spectroscopy of few-layers TaS2 and Mo-DopedTaS 2 with enhanced superconductivity

The use of simple, fast, and economic experimental tools to charac-terize low-dimensional materials is an important step in the process ofdemocratizing their use. Raman spectroscopy has arisen as a way ofindirectly determining the thickness of nanolayers of transition metaldichalcogenides (TMDs), avoiding the use of more expensive tools suchas atomic force microscopy, and it is therefore a widely used techniquein the study of semiconducting TMDs. However, the study of manymetallic TMDs in the limit of few atomic layers is still behind whencompared to their semiconducting counterparts, partly due to the lack ofsimilar alternative characterization studies. In this work the characteri-zation of the Raman spectrum, specifically of the E 22gg11 - and A1g -modes,of mechanically exfoliated Ta 1−xMoxS 2 , a metallic TMD which exhibitscharge density wave (CDW) formation and superconductivity, is pre-sented. The clear identification of contributions coming from the SiO 2 /Si substrate allowed the isolation of the individual E 22gg11 - and A1g -modes ofthe samples and, for the first time, the observation of a clear evolutionof their Raman shifts as a function of sample thickness. This provides away of indirectly determining sample thickness in the limit of few atomiclayers in Ta 1−xMox

Rendimiento y dinámica de crecimiento estacional de ballico perenne, pastoreado con ovinos a diferentes frecuencias e intensidades

The objective of the present study was to assess perennial ryegrass seasonal herbage accumulation, growth rate (GR), tiller population density (TPD) and weight (TW) at different grazing frequencies and intensities. Treatments consisted of two grazing frequencies (14 and 21 d in the rainy season and 35 and 42 d in the dry and cold seasons) and three grazing intensities: (hard 4-6 cm), medium (6-8 cm) and lax (8-10 cm) in a completely randomized block design with a factorial 2x3 arrangement and three replicates. In the rainy season herbage accumulation was 28 % greater (Pballico perenne a diferentes frecuencias e intensidades de pastoreo. Los tratamientos consistieron en dos frecuencias 14 ó 21 días (época de lluvias) y 35 ó 42 días (épocas fría y seca) y tres intensidades de pastoreo: alta (IA: 4 - 6 cm), media (IM: 6 - 8 cm) y ligera (IL: 8 - 10 cm), se utilizó un diseño de bloques completos al azar con arreglo factorial 2 x 3 y tres repeticiones. En lluvias el pastorear cada 21 dás superó en 28 % al de 14 días (4,437 vs 3,457 kg MS ha-1) y durante las épocas fría y seca se produjo 27 % más forraje al pastorear cada 35 que a 42 días (2,270 vs 1,787 kg MS ha-1). La IM produjo mayor acumulación de forraje que la IA e IL, durante las tres épocas del año. La TC fue mayor en la época de lluvias, especialmente en agosto, cuando se pastoreó a IM cada 21 días. En las épocas fría y seca la mayor TC se registró con pastoreos cada 35 días a IM. En agosto se observó la mayor DT promedio (8,042 m-2) y disminuyó a partir de septiembre. El PT determinó la mayor acumulación de forraje a los 21 días en la época de lluvias, en tanto que la DT incrementó el rendimiento de forraje al inicio del siguiente periodo de lluvias

Compositional mapping by Z-contrast imaging

This research was sponsored by the Office of Basic Energy Sciences, Materials Sciences and Engineering Division, U.S. Department of Energy (SJP, MV), by the Spanish MCI (projects CONSOLIDER INGENIO 2010 CSD2009-00013 andTEC2008-06756-C03-02/TEC,) and the Junta de Andalucía (PAI research’s groups TEP-120 and TIC-145; project P08-TEP-03516).Peer Reviewe

Synchronization of Discrete-Time Chaotic Fuzzy Systems by means of Fuzzy Output Regulation Using Genetic Algorithm

The synchronization of chaotic systems, described by discrete-time T-S fuzzy models, is treated by means of fuzzy output regulation theory. The conditions for designing a discrete-time output regulator are given in this paper. Besides, when the system does not fulfill the conditions for exact tracking, a new regulator based on genetic algorithms is considered. The genetic algorithms are used to approximate the adequate membership functions, which allow the adequate combination of local regulators. As a result, the tracking error is significantly reduced. Both the Complete Synchronization and the Generalized Synchronization problem are studied. Some numerical examples are used to illustrate the effectiveness of the proposed approach