1,241 research outputs found
Flume tests on fine soil reinforced with geosynthetics – walls of the salt pans (Aveiro lagoon, Portugal)
This paper presents exploratory work on the use of geosynthetics for reinforcing fine soils, particularly for applications in the Aveiro lagoon, Portugal. The behaviour of local fine soil reinforced with geosynthetics under hydraulic actions was studied using flume tests. The case study was a typical cross section of the walls of the salt pans of the Aveiro lagoon. A preliminary design of a structure was done, for different reinforcements (geogrid, geocomposite, association of geogrid and geotextile). Local soil was collected and characterised using laboratory tests. The flume tests included performing permeability, erosion and overtopping tests, for actions typical of the lagoon environment. The models reinforced with geogrid GGR exhibited the highest global permeability, due to the difficulty of soil lumps to penetrate the geogrid openings. Although this type of reinforcement provides low resistance to erosion, promoting vegetation growth or including other elements can reduce surface erosion. The other reinforcements (sheets) enabled containing the soil. Non-uniformity of the soil compaction caused local differences of permeability. Thus, ensuring uniform compaction on site is necessary; however it can be challenging, particularly for fine soils. The results indicate that seepage is likely to induce some clogging of the reinforcements. The reinforced soil models tested exhibited higher permeability and lower resistance to erosion and overtopping than the traditional solution (soil matrix with vegetation). The results indicate that a possible alternative solution for the walls could use fibre reinforcement. Further work is necessary to ensure adequate (low) permeability of new solutions for these wall
Reinforcement with geosynthetics of walls of the saltpans of the Aveiro lagoon
The aim of this article is to investigate the solution for the reinforcement of the walls of the saltpans of the Aveiro lagoon by using geosynthetics. For that purpose literature research has been done to collect both the properties and the geometry of the walls and of the soils. Simultaneously, methods for the design of reinforced soils using geosynthetics were collected, particularly to allow the consideration of two types of backfill soil: granular and fine. So, two solutions for such walls were studied using granular and fine soils, respectively. The design methods used were the ones proposed by: Jewell (1996) and Rogbeck et al. (2002) for granular soils and Naughton et al. (2001) for fine soils. Finally, the verification of the external stability of the profiles of a selected wall has been made using the methodology described in Eurocode 7: EN1997-1: 2004
Effect of geosynthetic reinforcement inclusion on the strength parameters and bearing ratio of a fine soil
This paper reports an investigation on the beneficial effects of reinforcing a fine soil with a geosynthetic (reinforcement geocomposite) and their behaviour under loading. The effectiveness of the reinforcement was investigated through triaxial and California Bearing Ratio, CBR, tests. The triaxial tests showed that including the reinforcement provided additional confinement to the reinforced soil samples, causing an increase in the corresponding strength parameters. However, the reinforcement decreased the secant stiffness modulus of the composite material, particularly for low strains. The CBR tests were performed on soaked samples, compacted for different initial water content values. The influence of increasing the number of reinforcement layers was also analysed. The results showed that the reinforced samples had a maximum bearing capacity larger than the unreinforced material. The reinforcing mechanisms observed in the CBR tests were membrane tension support and bearing capacity increase. Increasing the number of reinforcement layers induced an improved response of the soil-geosynthetic composite material, particularly for a water content lower than the optimum. An increase in the initial water content induced reductions of the bearing capacity of the soil, with different values, depending on position of the initial value relative to the optimum water content
Multidimensional continued fractions, dynamical renormalization and KAM theory
The disadvantage of `traditional' multidimensional continued fraction
algorithms is that it is not known whether they provide simultaneous rational
approximations for generic vectors. Following ideas of Dani, Lagarias and
Kleinbock-Margulis we describe a simple algorithm based on the dynamics of
flows on the homogeneous space SL(2,Z)\SL(2,R) (the space of lattices of
covolume one) that indeed yields best possible approximations to any irrational
vector. The algorithm is ideally suited for a number of dynamical applications
that involve small divisor problems. We explicitely construct renormalization
schemes for (a) the linearization of vector fields on tori of arbitrary
dimension and (b) the construction of invariant tori for Hamiltonian systems.Comment: 51 page
Regularisation Techniques for the Radiative Corrections of Wilson lines and Kaluza-Klein states
Within an effective field theory framework we compute the most general
structure of the one-loop corrections to the 4D gauge couplings in one- and
two-dimensional orbifold compactifications with non-vanishing constant gauge
background (Wilson lines). Although such models are non-renormalisable, we keep
the analysis general by considering the one-loop corrections in three
regularisation schemes: dimensional regularisation (DR), Zeta-function
regularisation (ZR) and proper-time cut-off regularisation (PT). The relations
among the results obtained in these schemes are carefully addressed. With
minimal re-definitions of the parameters involved, the results obtained for the
radiative corrections can be applied to most orbifold compactifications with
one or two compact dimensions. The link with string theory is discussed. We
mention a possible implication for the gauge couplings unification in such
models.Comment: 37 pages, 1 Figure, LaTeX; minor correction
Wilson lines corrections to gauge couplings from a field theory approach
Using an effective field theory approach, we address the effects on the gauge
couplings of one and two additional compact dimensions in the presence of a
constant background (gauge) field. Such background fields are a generic
presence in models with extra dimensions and can be employed for gauge symmetry
breaking mechanisms in the context of 4D N=1 supersymmetric models. The
structure of the ultraviolet (UV) and infrared (IR) divergences that the gauge
couplings develop in the presence of Wilson line vev's is investigated.
One-loop radiative corrections to the gauge couplings due to overlapping
effects of the compact dimensions and Wilson line vev's are computed for
generic 4D N=1 models. Values of Wilson lines vev's corresponding to points (in
the ``moduli'' space) of enhanced gauge symmetry cannot be smoothly reached
{\it perturbatively} from those corresponding to the broken phase. The one-loop
corrections are compared to their (heterotic) string counterpart in the ``field
theory'' limit alpha'->0 to show remarkably similar results when no massless
states are present in a Kaluza-Klein tower. An additional correction to the
gauge coupling exists in the effective field theory approach when for specific
Wilson lines vev's massless Kaluza-Klein states are present. This correction is
not recoverable by the limit alpha'->0 of the (infrared regularised) string
because the infrared regularisation limit and the limit alpha'->0 of the string
result do not commute.Comment: 38 pages, Latex, reference adde
A proposed methodology for the correction of the Leaf Area Index measured with a ceptometer for pinus and eucalyptus forests = Proposta de uma methodologia para a correcao do indice de area foliar medido pelo ceptometro em provoamentos de pinus e eucalyptus
Leaf area index (LAI) is an important parameter controlling many biological and physiological processes associated with vegetation on the Earth's surface, such as photosynthesis, respiration, transpiration,
carbon and nutrient cycle and rainfall interception. LAI can be measured indirectly by sunfleck ceptometers in an easy and non-destructive way but this practical methodology tends to underestimated when measured
by these instruments. Trying to correct this underestimation, some previous studies heave proposed the multiplication of the observed LAI value by a constant correction factor. The assumption of this work is LAI obtained from the allometric equations are not so problematic and can be used as a reference LAI to develop a new methodology to correct the ceptometer one. This new methodology indicates that the bias (the difference between the ceptometer and the reference LAI) is estimated as a function of the basal area per unit ground area and that bias is summed to the measured value. This study has proved that while the measured Pinus LAI needs a correction, there is no need for that correction for the Eucalyptus LAI. However, even for this last specie the proposed methodology gives closer estimations to the real LAI values
Influence of dietary Chlorella vulgaris and carbohydrate-active enzymes on growth performance, meat quality and lipid composition of broiler chickens
Article in pressHerein, we investigated the effect of
Chlorella vulgaris as ingredient (10% of incorporation) in
broiler diets, supplemented or not with 2 formulations of
Carbohydrate-Active enZymes (CAZymes; Rovabio
Excel AP and a mixture of recombinant CAZymes,
composed by an exo-b-glucosaminidase, an alginate
lyase, a peptidoglycan N-acetylmuramic acid deacetylase
and a lysozyme), on growth performance, meat quality,
fatty acid composition, oxidative stability, and sensory
traits. One hundred twenty 1-day-old Ross 308 male birds
were randomly assigned to one of the 4 experimental diets
(n 5 30): corn-soybean meal–basal diet (control), basal
diet with 10% C. vulgaris (CV), CV supplemented with
0.005% of a commercialCAZymecocktail (Rovabio Excel
AP), (CV1R), and CV supplemented with 0.01% of a 4-
CAZyme mixture previously selected (CV 1 M) during
the experimental period lasted from day 21 to day 35.
Body weight gain and feed conversion rate of broilers were
not affected by C. vulgaris but digesta viscosity increased more than 2-fold (P , 0.001) relative to the control. In
addition, neither cooking loss, shear force, juiciness, flavor
nor off-flavor was impaired by dietary treatments
(P.0.05). By contrast, the dietary C. vulgaris increased
tenderness, yellowness (b*) and total carotenoids in
breast and thigh meats. However, no additional protective
effect against lipid oxidation was observed in meat
with the inclusion of microalga. Chlorella vulgaris, independently
of CAZymes, had a minor impact on meat fatty
acid composition but improved the proportion of some
beneficial fatty acids. In summary, our data indicate a
slight improvement of broiler meat quality and lipid
nutritional value, without impairment of broilers’ growth
performance, thus supporting the usefulness of this
microalga in poultry diets, up to this high level of incorporation.
By contrast, the selected CAZyme mixtures
used do not significantly improve the release of microalga
nutrients in poultry diets, through the disruption of
microalga cell wall, which warrants further researchinfo:eu-repo/semantics/acceptedVersio
Apoio Em Rede: A Rede Humaniza Sus Conectando Possibilidades No Ciberespaço
This paper presents the HUmanizaSUS Network (Rede HumanizaSUS) as a virtual environment connecting practices and knowledge about SUS (Brazilian National Health System), conveying the support function in a network. Based on the theoretical framework of Collective Intelligence, we present some dimensions of support experienced on Rede HumanizaSUS as a network intervention technology for strengthening the virtual environment of SUS or CiberespaSUS. © 2016, Fundacao UNI Botucatu/UNESP. All rights reserved.205733734
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