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1

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Seed-layer effect on the microstructure and magnetic properties of Co/Pd multilayers (2001)

Roy, A. G. ; Laughlin, D. E.

[S.l.] : American Institute of Physics (AIP)

Journal of Applied Physics 89 (2001), S. 7531-7533

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ISSN: 1089-7550

Source: AIP Digital Archive

Topics: Physics

Notes: We have investigated Co/Pd multilayers deposited on either Ta or indium tin oxide (ITO) seed layers as a potential perpendicular recording media. We have examined the microstructural evolution of the films deposited on the two different types of seed layers and related it to the magnetic properties of the films. Ta underlayer produces a strong 〈111〉 fiber texture in the multilayer while ITO produces randomly oriented grains. Transmission electron microscopy reveals a microstructure of columnar grains separated by less dense material at the boundaries for the multilayers with an ITO underlayer. However, the less dense material is absent when using a Ta underlayer. The films exhibited strong perpendicular anisotropy and a higher coercivity of ∼6800 Oe and squareness of ∼0.99 are obtained for the films deposited on an ITO seed layer. The differences in the value of coercivity and squareness in the films can be correlated with the differences in the evolution of microstructures for different seed layers. © 2001 American Institute of Physics.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1063/1.1360685

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The feeding behaviour of juvenile Atlantic salmon in relation to turbulent flow (2005)

Enders, E. C. ; Buffin-Bélanger, T. ; Boisclair, D. ; [et al.]

Oxford, UK; Malden, USA : Blackwell Publishing Ltd/Inc.

Journal of fish biology 66 (2005), S. 0

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ISSN: 1095-8649

Source: Blackwell Publishing Journal Backfiles 1879-2005

Topics: Biology

Notes: The feeding behaviour of juvenile Atlantic salmon Salmo salar in the Sainte-Marguerite River, Quebec, Canada, varied with the characteristics of turbulent flow. Simulations indicated that juveniles would decrease their swimming costs during attacks by 19·8% in low and by 31·1% in high turbulent conditions by initiating movements in low-speed flow events. The real swimming costs did not differ from the swimming costs estimated for a situation where fish initiate their movements at randomly selected flow velocities. The juvenile Atlantic salmon did not seem to prefer low-speed flow events when initiating their movements. The proportion of time used for movements by fish decreased with an increase in the mean and the s.d. of the flow velocity.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1111/j.0022-1112.2005.00599.x

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On the interaction of turbulent flow and feeding behaviour of juvenile Atlantic Salmon (Salmo salar) (2003)

Enders, E. C. ; Buffin-Bélanger, T. ; Boisclair, D. ; [et al.]

Oxford, UK; Malden, USA : Blackwell Science Ltd/Inc

Journal of fish biology 63 (2003), S. 0

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ISSN: 1095-8649

Source: Blackwell Publishing Journal Backfiles 1879-2005

Topics: Biology

Notes: Anthropogenic activities can dramatically modify the riverine habitat of juvenile Atlantic salmon (Salmo salar). In the perspective of protecting and restoring the fluvial habitat, bioenergetic models are often used to estimate fish habitat quality. These models determine the habitat quality as the ratio between the energetic gains (food) and costs (growth, metabolism) of a fish. The energetic costs of swimming in a river are generally estimated using the average flow velocity without consideration of the effect of turbulence. Juvenile Atlantic salmon (JAS) live in rivers characterized by intense velocity fluctuations, which are often described as a succession of high- and low-speed flow regions. These flow structures are likely to affect the JAS activity that consists of long periods of sit-and-wait at the top of a protuberant rock interrupted by short bursting motions to capture drifting food particles. To minimize the energetic costs, it is hypothesized that JAS use low-speed flow regions to initiate and undertake their feeding motions. To improve bioenergetic modelling, this study aimed at analyzing the relation between turbulent flow structures and the feeding behaviour of JAS in a natural gravel-bed river. We filmed eight JAS during 30 min with a submersible video camera while simultaneously measuring velocity fluctuations close to the fish in the St. Marguerite River, Quebec, Canada. Our results show that the proportion of time used for feeding motions decreases with increasing turbulent intensity and mean flow velocity; and that JAS do not seem to prefer low-speed flow regions to initiate their feeding motions.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1111/j.1095-8649.2003.0216l.x

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Differences in the energetic cost of swimming in turbulent flow between wild, farmed and domesticated juvenile Atlantic salmon Salmo salar (2004)

Enders, E. C. ; Boisclair, D. ; Roy, A. G.

Oxford, UK; Malden, USA : Blackwell Science Ltd

Journal of fish biology 65 (2004), S. 0

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ISSN: 1095-8649

Source: Blackwell Publishing Journal Backfiles 1879-2005

Topics: Biology

Notes: Domestication has been shown to have an effect on morphology and behaviour of Atlantic salmon (Salmo salar). We compared swimming costs of three groups of juvenile Atlantic salmon subject to different levels of domestication: (1) wild fish; (2) first generation farmed fish origination from wild genitors; and (2) seventh generation farmed fish originating from Norwegian aquaculture stocks. We assessed swimming costs under two types of turbulent flow (one mean flow velocity of 23 cm s−1 and two standard deviations of flow velocity of 5 and 8 cm s−1). Respirometry experiments were conducted with fish in a mass range of 5–15 g wet at a water temperature of 15° C. Our results confirm (1) that net swimming costs are affected by different levels of turbulence such that, for a given mean flow velocity, fish spent 1·5-times more energy as turbulence increased, (2) that domesticated fish differed in their morphology (having deeper bodies and smaller fins) and in their net swimming costs (being up to 30·3% higher than for wild fish) and (3) that swimming cost models developed for farmed fish may be also be applied to wild fish in turbulent environments.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1111/j.0022-1112.2004.0559h.x

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Turbulent flow structure at concordant and discordant open-channel confluences (1996)

Biron, P. ; Roy, A. G. ; Best, J. L.

Springer

Experiments in fluids 21 (1996), S. 437-446

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ISSN: 1432-1114

Source: Springer Online Journal Archives 1860-2000

Topics: Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics

Notes: Abstract Models of flow at river-channel confluences that consist of two concordant confluent channels with avalanche faces dipping into a scour zone are limited because this morphology may be the exception rather than the rule in nature. In this paper the mean and turbulent flow structure in the streamwise and vertical directions at both concordant and discordant laboratory confluences were examined in order to determine the effect of bed discordance on the flow field, and to assess its influence on sediment transport. Instantaneous velocities were measured with a laser Doppler anemometer using a dense spatial sampling grid. The spatial distribution of normal stress varies with bed geometry as bed discordance generates a distortion of the mixing layer between the confluent streams. Turbulent shear stress is larger in the discordant bed case and its peak is associated with the position of the mixing layer whereas for concordant beds the zone of mixing is characterised by a decrease in the Reynolds shear stress. Quadrant analysis also revealed differential dominating quadrants between the two bed geometries which will influence sediment transport routing and, consequently, the resulting bed morphology. These results highlight the need for significant modifications to current models of confluence flow dynamics in order to account for the bed configuration.

Type of Medium: Electronic Resource

URL: http://dx.doi.org/10.1007/BF00189046

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