24 research outputs found

    Detector Description and Performance for the First Coincidence Observations between LIGO and GEO

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    For 17 days in August and September 2002, the LIGO and GEO interferometer gravitational wave detectors were operated in coincidence to produce their first data for scientific analysis. Although the detectors were still far from their design sensitivity levels, the data can be used to place better upper limits on the flux of gravitational waves incident on the earth than previous direct measurements. This paper describes the instruments and the data in some detail, as a companion to analysis papers based on the first data.Comment: 41 pages, 9 figures 17 Sept 03: author list amended, minor editorial change

    Three-dimensional direct numerical simulation of surface-tension-gradient effects on the leveling of an evaporating multicomponent fluid

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    Mathematical and numerical modeling of drying coating layers is of interest to both industrial and academic communities. Compositional changes that occur during the drying process make the implementation of practical and efficient numerical models rather difficult. In this paper we present a three-dimensional mathematical and numerical model based on the lubrication approximation for the flow of drying paint films on horizontal substrates. The paint is modeled as a multicomponent liquid with one nonvolatile and one volatile component, termed the "resin" and the "solvent" respectively. Our model includes the effects of surface tension and gravitational forces as well as surface tension gradient effects which arise due to solvent evaporation. The dependence of viscosity, diffusivity, and evaporation rate on resin concentration is also incorporated in the model. A closed-form Linearized solution has been found for coating layers that are of almost uniform thickness. The numerical solution agrees closely with the linear solution in the appropriate Limit. A model simulation demonstrates the effect of surface tension gradients due to compositional changes in a three-dimensional flow field, and we suggest methods by which these gradients may be used to obtain a more uniform final coating layer

    Substituição do feno de coastcross por casca de soja na alimentação de cabras em lactação Replacement of coastcross hay by soybean hulls in diets for lactating goats

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    Objetivou-se com este trabalho verificar a resposta de cabras em lactação alimentadas com dietas contendo casca de soja em substituição ao feno de coastcross. Trinta e seis cabras (38±5 dias em lactação; 2,1±0,4 kg/dia) foram distribuídas em delineamento experimental de blocos completos casualizados e confinadas por oito semanas. As dietas foram compostas de 50% de volumoso e 50% de concentrado e com o mesmo teor de fibra em detergente neutro. A casca de soja substituiu o feno de coastcross em 0, 33, 67 ou 100% da matéria seca (MS). O consumo de matéria seca e a eficiência alimentar apresentaram resposta quadrática aos teores de casca de soja na dieta. A produção de leite e a variação do peso corporal não foram alteradas, porém a concentração de gordura e lactose do leite aumentou e os tempos gastos com ruminação e mastigação decresceram com a inclusão da casca de soja na dieta. A casca de soja pode substituir totalmente o feno de coastcross em dietas para cabras em lactação, pois essa substituição não prejudica a produção de leite e aumenta o teor de gordura e lactose do leite. Em comparação ao feno picado de coastcross, a casca de soja apresenta menor efetividade em estimular a ruminação e a mastigação.<br>The objective of this experiment was to verify the response of lactating goats fed diets with different levels (content) of soybean hulls replacing coastcross hay (Cynodon sp.) on performance. Thirty-six lactating Saanen goats (38±5 days of lactation; 2.1±0.4 kg/day) were assigned to a randomized complete blocks design and housed for 8 weeks. Goats were fed diets of 50% roughage and 50% concentrate, but with the same amount of neutral detergent fiber. Soybean hulls replaced hay by 0, 33, 67 or 100% of the dry matter (DM). Dry matter and NDF intake and feed efficiency showed a quadratic response to the levels of soybean hulls in the diet. Milk yield and body weight variations did not change; however, milk fat, lactose and total solids concentration increased while time spent with rumination and chewing decreased, when soybean hulls were added to the diet. Soybean hulls can replace entirely coastcross hay in diets for lactating goats, with no detrimental effect on milk yield or with an increase on milk fat and lactose concentration. Compared with chopped coastcross hay, soybean hulls show less effectiveness to stimulate rumination and chewing

    Sliding droplets of Xanthan solutions: A joint experimental and numerical study

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    We have investigated the sliding of droplets made of solutions of Xanthan, a stiff rodlike polysaccharide exhibiting a non-Newtonian behavior, notably characterized by a shear thinning viscosity accompanied by the emergence of normal stress difference as the polymer concentration is increased. These experimental results are quantitatively compared with those of Newtonian fluids (water). The impact of the non-Newtonian behavior on the sliding process was shown through the relation between the average dimensionless velocity (i.e. the capillary number) and the dimensionless volume forces (i.e. the Bond number). To this aim, it is needed to define operative strategies to compute the capillary number for the shear thinning fluids and compare with the corresponding Newtonian case. The resulting capillary number for the Xanthan solutions scales linearly with the Bond number at small inclinations, as well known for Newtonian fluids, while it shows a plateau as the Bond number is increased. Experimental data were complemented with lattice Boltzmann numerical simulations of sliding droplets, aimed to disentangle the specific contribution of shear thinning and elastic effects on the sliding behavior. In particular the deviation from the linear (Newtonian) trend is more likely attributed to the emergence of normal stresses inside the non-Newtonian droplet
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