2,153 research outputs found
Simulation study for investment decisions on the EcoBoost camshaft machining line
Design/redesign of manufacturing systems is a complex, risky, and expensive task. Ford Motor Company’s Valencia Engine Plant faces this challenge as it plans to upgrade its machining and assembly lines to introduce the new EcoBoost engines. The research project described in this paper aimed to support the transition process particularly at the camshaft machining line by using simulation modelling techniques. A series of experiments was carried out using the simulation model developed, and recommendations were proposed based on the results of these experiments to support the decision as to where to invest on the line. The outcomes from the research project indicated that investment is required in terms of increasing the capacity of two bottleneck operations through retooling and improving the conveyor routing logic in one key area.
Keywords: simulation modelling, closed-loop network, automotive production system
On the nature of some SGRs and AXPs as rotation-powered neutron stars
We investigate the possibility that some SGRs/AXPs could be canonical
rotation-powered pulsars using realistic NS structure parameters instead of
fiducial values. We show that realistic NS parameters lowers the estimated
value of the magnetic field and radiation efficiency, ,
with respect to estimates based on fiducial NS parameters. We show that nine
SGRs/AXPs can be described as canonical pulsars driven by the NS rotational
energy, for computed in the soft (2--10~keV) X-ray band. We compute the
range of NS masses for which . We discuss the observed
hard X-ray emission in three sources of the group of nine potentially
rotation-powered NSs. This additional hard X-ray component dominates over the
soft one leading to in two of them. We show that 9
SGRs/AXPs can be rotation-powered NSs if we analyze their X-ray luminosity in
the soft 2--10~keV band. Interestingly, four of them show radio emission and
six have been associated with supernova remnants (including Swift J1834.9-0846
the first SGR observed with a surrounding wind nebula). These observations give
additional support to our results of a natural explanation of these sources in
terms of ordinary pulsars. Including the hard X-ray emission observed in three
sources of the group of potential rotation-powered NSs, this number of sources
with becomes seven. It remains open to verification
1) the accuracy of the estimated distances and 2) the possible contribution of
the associated supernova remnants to the hard X-ray emission.Comment: 11 pages, 14 figures, to appear in A&
JPCam: A 1.2Gpixel camera for the J-PAS survey
JPCam is a 14-CCD mosaic camera, using the new e2v 9k-by-9k 10microm-pixel
16-channel detectors, to be deployed on a dedicated 2.55m wide-field telescope
at the OAJ (Observatorio Astrofisico de Javalambre) in Aragon, Spain. The
camera is designed to perform a Baryon Acoustic Oscillations (BAO) survey of
the northern sky. The J-PAS survey strategy will use 54 relatively narrow-band
(~13.8nm) filters equi-spaced between 370 and 920nm plus 3 broad-band filters
to achieve unprecedented photometric red-shift accuracies for faint galaxies
over ~8000 square degrees of sky. The cryostat, detector mosaic and read
electronics is being supplied by e2v under contract to J-PAS while the
mechanical structure, housing the shutter and filter assembly, is being
designed and constructed by a Brazilian consortium led by INPE (Instituto
Nacional de Pesquisas Espaciais). Four sets of 14 filters are placed in the
ambient environment, just above the dewar window but directly in line with the
detectors, leading to a mosaic having ~10mm gaps between each CCD. The massive
500mm aperture shutter is expected to be supplied by the Argelander-Institut
fur Astronomie, Bonn. We will present an overview of JPCam, from the filter
configuration through to the CCD mosaic camera. A brief outline of the main
J-PAS science projects will be included.Comment: 11 pages and 9 figure
Early feeding to modify digestive enzyme activity in broiler chickens
Objective. To evaluate the effect on digestive enzyme activity in broiler chickens by providing food in the first 48 hrs. after birth. Materials and methods. After incubating 300 fertile eggs from Hubbard breeding and immediately after hatching, the chicks were randomly assigned to treatments: fasting (from hatching to 48 hrs.); Hydrated Balanced Food (HBF) from birth to 48 hrs.; commercial hydrating supplement (CHS) from birth to 48 hrs. The diets were provided ad libitum. After 48 hrs. a commercial diet was fed. At birth and at 48 and 72 hrs. of age 30 chicks/treatment were sacrificed to determine the enzyme activity of maltase, sucrase, alkaline phosphatase, phytase, a-amylase, trypsin and lipase in samples of duodenal or pancreatic homogenate. Results. The supply of HBF or CHS during the first 48 hrs. of life increased the activity of maltase, sucrase and phytase in the first 3 days of life, with values between 1.2 and up to 4-fold compared to the control (p<0.05). Chickens that fasted for the first 48 hrs. had higher activity of the pancreatic enzymes a-amylase, trypsin, and lipase at 72 hrs. of life (p<0.05). Conclusions. The food supply in the first 48 hrs. after hatching increases the duodenal enzyme activity in the intestinal brush border during the first 3 days of age in broiler chickens
The unusual 2006 dwarf nova outburst of GK Perseii
The 2006 outburst of GK Perseii differed significantly at optical and
ultraviolet wavelengths from typical outbursts of this object. We present
multi-wavelength (X-ray, UV and optical) Swift and AAVSO data, giving
unprecedented broad-band coverage of the outburst, allowing us to follow the
evolution of the longer-than-normal 2006 outburst across these wavelengths. In
the optical and UV we see a triple-peaked morphology with maximum brightness
~1.5 magnitudes lower than in previous years. In contrast, the peak hard X-ray
flux is the same as in previous outbursts. We resolve this dichotomy by
demonstrating that the hard X-ray flux only accounts for a small fraction of
the total energy liberated during accretion, and interpret the optical/UV
outburst profile as arising from a series of heating and cooling waves
traversing the disc, caused by its variable density profile.Comment: 9 pages, 7 figures, accepted for publication in MNRA
On the Optical Transients from Double White-dwarf Mergers
Double white dwarf (DWD) mergers are relevant astrophysical sources expected to produce massive, highly magnetized white dwarfs (WDs), supernovae (SNe) Ia, and neutron stars (NSs). Although they are expected to be numerous sources in the sky, their detection has evaded the most advanced transient surveys. This article characterizes the optical transient expected from DWD mergers in which the central remnant is a stable (sub-Chandrasekhar) WD. We show that the expansion and cooling of the merger's dynamical ejecta lead to an optical emission peaking at 1–10 days postmerger, with luminosities of 1040–1041 erg s−1. We present simulations of the light curves, spectra, and the color evolution of the transient. We show that these properties, together with the estimated rate of mergers, are consistent with the absence of detection, e.g., by the Zwicky Transient Facility. More importantly, we show that the Legacy Survey of Space and Time of the Vera C. Rubin Observatory will likely detect a few/several hundred per year, opening a new window to the physics of WDs, NSs, and SNe Ia
Correlações genéticas entre diferentes metodologias de temperamento na raça Nelore.
Objetivou-se com este trabalho verificar as correlações genéticas entre metodologias de temperamento. Foram utilizados dados de 800 novilhos da raça Nelore, de três safras, oriundos de cinco fazendas, confinados aproximadamente aos 18 meses de idade, em dois locais. Pelo menos duas medidas de reatividade foram obtidas em cada animal utilizando o escore composto (EC) na balança de pesagem e a velocidade de saÃda (VS). Para estimação dos componentes de variância e covariância foi utilizado o método da máxima verossimilhança restrita. O modelo utilizado incluiu os efeitos fixos de grupo de contemporâneos (ano de nascimento-origem-local de confinamento-data da medida) e os efeitos aleatórios aditivo direto e de ambiente permanente do animal, além do resÃduo. As correlações genéticas entre deslocamento (DESL), tensão (TENS) e EC e entre DESL e VS foram altas (0,93 a 1,00), enquanto as correlações genéticas de TENS (0,49) e EC (0,29) com VS foram mediana e baixa, respectivamente
Estimativas de parâmetros genéticos para reatividade na raça Nelore.
Objetivou-se com este trabalho verificar a possibilidade de usar a reatividade como critério de seleção, por meio da avaliação de parâmetros genéticos. Foram utilizados dados de 800 novilhos da raça Nelore, oriundos de cinco fazendas, de três safras, confinados aproximadamente aos 18 meses de idade, em dois locais. Pelo menos duas medidas de reatividade foram obtidas em cada animal. As análises visaram estimar, pelo método de máxima verossimilhança restrita, parâmetros genéticos para escores de deslocamento (DESL), tensão (TENS), escore composto (EC) e velocidade de saÃda (VsaÃda). O modelo animal utilizado incluiu os efeitos fixos de grupo de contemporâneos (ano de nascimento-origem-local de confinamento-data da medida) e os efeitos aleatórios aditivo direto e de ambiente permanente do animal, além do resÃduo. As estimativas de herdabilidade obtidas foram iguais a 0,05 ± 0,03 (DESL), 0,08 ± 0,04 (TENS), 0,05 ± 0,03 (EC) e 0,00 ± 0,02 (VSaÃda), sugerindo pouco campo para seleção para essas caracterÃsticas. Os valores de repetibilidade obtidos para essas caracterÃsticas foram, na mesma ordem, iguais a 0,34; 0,32; 0,35 e 0,20, respectivamente, indicando que mais de uma medida deve ser tomada em cada animal para avaliar sua reatividade
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