3,448 research outputs found
Effects of long-term farmyard manure applications on soil organic matter, nitrogen mineralization and crop yield – a modeling study –
To develop sustainable cropping systems we need to predict both short-term and long-term effects of management practices on soil fertility. For this purpose agro-ecosystem simulation models are valuable tools. We used the Daisy model to simulate a three-year crop rotation (beetroot, onion, white clover, potato) over a period of 40 years. With this rotation, three rates of farmyard manure were tested (0, 15, 28 t ha-1 year-1). After 40 years without manure soil organic matter carbon (SOM-C) decreased by approximately 40%, and increased by 27% with the highest application rate. SOM turnover did not reach equilibrium at the end of the experiment. Nitrogen mineralization from SOM followed in the long-term (40 years) the slowly changing time courses of SOM. However, manure applications affected mineralization and hence crop yield and nitrogen losses much more in the short-term (1 to 2 years) than in the long-term
A new beam emission polarimetry diagnostic for measuring the magnetic field line angle at the plasma edge of ASDEX Upgrade
A new edge beam emission polarimetry diagnostic dedicated to the measurement of the magnetic
field line angle has been installed on the ASDEX Upgrade tokamak. The new diagnostic relies on the
motional Stark e
ff
ect and is based on the simultaneous measurement of the polarization direction of
the linearly polarized
π
(parallel to the electric field) and
σ
(perpendicular to the electric field) lines of
the Balmer line D
α
. The technical properties of the system are described. The calibration procedures
are discussed and first measurements are presentedEuropean Union (EUROfusion 633053)European Union (EUROfusion Grant WP14-FRF-IPP)Ministerio de Economía y Competitividad (Grant No. FJCI-201422139
Morphology of the canine omentum, part 2: the omental bursa and its compartments materialized and explored by a novel technique
The canine omental bursa is a virtual cavity enclosed by the greater and lesser omentum. While previous representations of this bursa were always purely schematic, a novel casting technique was developed to depict the three-dimensional organization of the omental bursa more consistently. A self-expanding polyurethane-based foam was injected into the omental bursa through the omental foramen in six dogs. After curing and the subsequent maceration of the surrounded tissues, the obtained three-dimensional casts could clearly and in a reproducible way reveal the omental vestibule, its caudal recess and the three compartments of the splenic recess. The cast proved to be an invaluable study tool to identify the landmarks that define the enveloping omentum. In addition, the polyurethane material can easily be discerned on computed tomographic images. When the casting technique is preceded by vascular injections, the blood vessels that supply the omentum can be outlined as well
Impurity and Trace Tritium Transport in Tokamak Edge Turbulence
The turbulent transport of impurity or minority species, as for example
Tritium, is investigated in drift-Alfv\'en edge turbulence. The full effects of
perpendicular and parallel convection are kept for the impurity species. The
impurity density develops a granular structure with steep gradients and locally
exceeds its initial values due to the compressibility of the flow. An
approximate decomposition of the impurity flux into a diffusive part and an
effective convective part (characterized by a pinch velocity) is performed and
a net inward pinch effect is recovered. The pinch velocity is explained in
terms of Turbulent Equipartition and is found to vary poloidally. The results
show that impurity transport modeling needs to be two-dimensional, considering
besides the radial direction also the strong poloidal variation in the
transport coefficients.Comment: 12 Pages, 5 Figure
Puente grúa birraíl de 2x1000 kg y 24 m de luz, dotado de carro giratorio con un polipasto central de doble salida
El presente proyecto responde a una petición de oferta solicitada por un taller de decoletaje,
para la instalación de un puente grúa que mejore el suministro del material, del almacén de
materia prima a los tornos de decoletaje. El material consiste en paquetes de barras de
longitud máxima 4 m y un peso máximo de 1000 kg por paquete. Con el actual puente grúa,
de un gancho de elevación y 1000 kg de carga nominal, el material es transportado por dos
operarios, entre los dos manejan la botonera y dirigen los paquetes manualmente hacia los
cargadores de las máquinas. Se pretende que todo el transporte de material sea realizado
por un solo operario y que además sea capaz de llevar dos paquetes cada vez, en vez de
uno solo como actualmente.
Como se trata de una máquina hecha a medida, de la que solamente se fabricará una
unidad, el objetivo del proyecto será satisfacer las especificaciones concretas del cliente,
cumpliendo todos los requisitos mecánicos y en cuanto a seguridad, sin olvidar la sencillez y
funcionalidad de manera que no se encarezca el proyecto inútilmente.
La mejor solución encontrada consiste en que los movimientos de giro de los paquetes los
realice el puente grúa, y el operario solamente maneje la botonera. Para conseguir el
movimiento de giro de los paquetes, es necesario que estos estén sujetos por dos puntos
separados, y para ello se ha diseñado un polipasto de doble salida con dos ganchos de
sujeción separados dos metros. El movimiento de giro es proporcionado por un carro
giratorio sobre el que está sujeto el polipasto de doble salida. Este carro gira por medio de
cuatro ruedas sobre un camino de rodadura circular soldado sobre otro carro de movimiento
transversal. Las dos salidas de cable del polipasto son reenviadas, mediante dos poleas
fijadas también al carro giratorio, hacia los dos ganchos de elevación, por tanto cuando el
carro giratorio gira, también giran el polipasto y los dos ganchos, haciendo girar la carga. El
movimiento de traslación de la carga a través del puente birraíl es proporcionado por un
carro de movimiento transversal. Sobre dicho carro se apoya y gira el carro giratorio con el
polipasto de doble salida, por lo tanto cuando se desplaza dicho carro también se desplaza
la carga. Dicho carro transversal se desplaza sobre un puente birraíl, el cual proporciona el
movimiento transversal a través de la nave, a todo el puente grúa.
Esta solución cumple todos los requisitos del cliente de la manera más sencilla y económica
posible, cumpliendo todos los requisitos mecánicos y en cuanto a seguridad
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