326 research outputs found
Testing the performance of rival warehousing policies through discrete event simulation
This research tested the performance of alternative warehouse designs concerning the picking process. The chosen performance measures were Travel Distance and Total Fulfilment Time. An explanatory case study was built up around a model implemented with SIMUL8. Hypotheses were set by selecting outcomes from the literature survey matching popular empirical findings. 17.4% reductions were found for Total Fulfilment Time and Resource Utilisation. The latter was then used as a proxy for operational efficiency. Literal replication of theoretical data-patterns was considered as an internal validity sign. Assessing the estimated changes benefits ahead of implementation was found to be a contribution to practice.info:eu-repo/semantics/publishedVersio
Avaliação de genótipos de mamoeiro (Carica papaya L.) para resistência à Phytophthora palmivora Butler.
A fruticultura é um dos segmentos de maior crescimento na agricultura e o mamoeiro (Carica papaya L.) aparece como um dos destaques, principalmente após a recente abertura do mercado norte- americano para a exportação de mamão produzido no país. O mamoeiro pode ser considerado originário do noroeste da América do Sul e América Central, com as principais áreas comerciais localizadas entre as latitudes 23oN e S, apesar de serem encontrados plantios em latitudes de até 32oN e S
The Stellar Content of Obscured Galactic Giant HII Regions V: G333.1--0.4
We present high angular resolution near--infrared images of the obscured
Galactic Giant HII (GHII) region G333.1--0.4 in which we detect an OB star
cluster. For G333.1--0.4, we find OB stars and other massive objects in very
early evolutionary stages, possibly still accreting. We obtained --band
spectra of three stars; two show O type photospheric features, while the third
has no photospheric features but does show CO 2.3 m band--head emission.
This object is at least as hot as an early B type star based on its intrinsic
luminosity and is surrounded by a circumstellar disc/envelope which produces
near infrared excess emission. A number of other relatively bright cluster
members also display excess emission in the --band, indicative of
disks/envelopes around young massive stars. Based upon the O star photometry
and spectroscopy, the distance to the cluster is 2.6 0.4 kpc, similar to
a recently derived kinematic (near side) value. The slope of the --band
luminosity function is similar to those found in other young clusters. The mass
function slope is more uncertain, and we find - for stars with M M where the upper an lower limits are
calculated independently for different assumptions regarding the excess
emission of the individual massive stars. The number of Lyman continuum photons
derived from the contribution of all massive stars in the cluster is 0.2
. The
integrated cluster mass is 1.0
.Comment: 31 pages, including 12 figures and 3 tables. Accepted for publication
in the A
Three-dimensional CFD analysis of the hand and forearm in swimming
The purpose of this study was to analyze the hydrodynamic characteristics of a realistic model of an elite
swimmer hand/forearm using three-dimensional computational fluid dynamics techniques. A three-dimensional
domain was designed to simulate the fluid flow around a swimmer hand and forearm model in different orientations
(0°, 45°, and 90° for the three axes Ox, Oy and Oz). The hand/forearm model was obtained through
computerized tomography scans. Steady-state analyses were performed using the commercial code Fluent.
The drag coefficient presented higher values than the lift coefficient for all model orientations. The drag coefficient
of the hand/forearm model increased with the angle of attack, with the maximum value of the force
coefficient corresponding to an angle of attack of 90°. The drag coefficient obtained the highest value at an
orientation of the hand plane in which the model was directly perpendicular to the direction of the flow. An
important contribution of the lift coefficient was observed at an angle of attack of 45°, which could have an
important role in the overall propulsive force production of the hand and forearm in swimming phases, when
the angle of attack is near 45°.Lif
Computational fluid dynamics applied to competitive swimming: the role of finger position
The best fingers’ relative position during the underwater
path of the stroke cycle in swimming seems to be an unclear
issue. Even in elite level swimmers, different relative positions of thumb
and finger spreading can be observed. The aim of the current abstract
was to present the hydrodynamic characteristics of a true model of a
swimmer’s hand with different fingers’ positions using computational
CFD
Avaliação da deficiência hídrica em genótipos de mamoeiro.
O crescimento e a produtividade do mamoeiro são afetados por inúmeros fatores, com destaque para o estresse hídrico, que pode reduzir a produtividade do mamoeiro em até 22%. Os estudos de caracterização genotípica associados a componentes fisiológicos ainda são restritos, em decorrência da complexidade das respostas das plantas frequentemente submetidas a estresses ambientais
Computational fluid dynamics vs. inverse dynamics methods to determine passive drag in two breaststroke glide positions
Computational fluid dynamics (CFD) plays an important role to quantify, understand and "observe" the water movements around the human body and its effects on drag (D). We aimed to investigate the flow effects around the swimmer and to compare the drag and drag coefficient (CD) values obtained from experiments (using cable velocimetry in a swimming pool) with those of CFD simulations for the two ventral gliding positions assumed during the breaststroke underwater cycle (with shoulders flexed and upper limbs extended above the head-GP1; with shoulders in neutral position and upper limbs extended along the trunk-GP2). Six well-trained breaststroke male swimmers (with reasonable homogeneity of body characteristics) participated in the experimental tests; afterwards a 3D swimmer model was created to fit within the limits of the sample body size profile. The standard k-ε turbulent model was used to simulate the fluid flow around the swimmer model. Velocity ranged from 1.30 to 1.70 m/s for GP1 and 1.10 to 1.50 m/s for GP2. Values found for GP1 and GP2 were lower for CFD than experimental ones. Nevertheless, both CFD and experimental drag/drag coefficient values displayed a tendency to jointly increase/decrease with velocity, except for GP2 CD where CFD and experimental values display opposite tendencies. Results suggest that CFD values obtained by single model approaches should be considered with caution due to small body shape and dimension differences to real swimmers. For better accuracy of CFD studies, realistic individual 3D models of swimmers are required, and specific kinematics respected.info:eu-repo/semantics/publishedVersio
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