Distribuição de macroalgas nativas e exóticas no substrato duro subtidal do porto de Sines

Dissertação para obtenção do Grau de Mestre em Ecologia, gestão e modelação de recursos marinhosTendo em conta o potencial impacte de espécies introduzidas em ambientes marinhos, observações de algas exóticas realizadas em estudos anteriores sobre o substrato duro subtidal do Porto de Sines e o facto de este porto ter um intenso tráfego marítimo que inclui navios e outras embarcações provenientes de diversas regiões longínquas, foi estudada a abundância e distribuição de macroalgas exóticas em substratos duros subtidais do porto de Sines, dando especial atenção à macroalga exótica Asparagopsis taxiformis e incluindo o estudo da distribuição de macroalgas nativas. A amostragem deste estudo foi realizada em mergulho com escafandro autónomo e decorreu no Verão de 2004. Com o objectivo de estudar a abundância e a distribuição espacial de A. taxiformis, foi feita uma procura exaustiva desta espécie a uma profundidade de 3 a 10 m em 9 áreas dentro do porto de Sines. Esta espécie foi encontrada com maior abundância no porto de recreio, onde foi estimada quantitativamente a sua percentagem de cobertura, sem recurso a amostragem destrutiva. Com vista ao estudo da distribuição espacial de algas exóticas e nativas no porto de Sines, foram amostradas 6 áreas a uma profundidade de 3 a 6 m. Em cada área, foi amostrada destrutivamente a cobertura de macroepibentos. A alga exótica Asparagopsis taxiformis apenas foi encontrada em duas das nove áreas amostradas. Foi no porto de Recreio que a sua abundância foi mais elevada atingindo, no máximo, 24% de cobertura. No estudo da distribuição espacial de macroalgas exóticas e nativas, foram encontradas três espécies exóticas: Antithamnionella ternifolia, Colpomenia peregrina e Falkenbergia rufolanosa. Neste estudo, as análises multivariadas da estrutura de comunidades de macroalgas revelaram diferenças significativas entre as áreas. Excepto no caso da alga C. peregrina, em que atividades de aquacultura terão sido as principais responsáveis pela sua introdução na costa portuguesa, os vectores de introdução de A. ternifolia, A. taxiformis e F. rufolanosa nesta costa deverão estar relacionados com a utilização de navios e outras embarcações

Durability of Mortar Incorporating Ferronickel Slag Aggregate and Supplementary Cementitious Materials Subjected to Wet–Dry Cycles

This paper presents the strength and durability of cement mortars using 0–100% ferronickel slag (FNS) as replacement of natural sand and 30% fly ash or ground granulated blast furnace slag (GGBFS) as cement replacement. The maximum mortar compressive strength was achieved with 50% sand replacement by FNS. Durability was evaluated by the changes in compressive strength and mass of mortar specimens after 28 cycles of alternate wetting at 23 °C and drying at 110 °C. Strength loss increased by the increase of FNS content with marginal increases in the mass loss. Though a maximum strength loss of up to 26% was observed, the values were only 3–9% for 25–100% FNS contents in the mixtures containing 30% fly ash. The XRD data showed that the pozzolanic reaction of fly ash helped to reduce the strength loss caused by wet–dry cycles. Overall, the volume of permeable voids (VPV) and performance in wet–dry cycles for 50% FNS and 30% fly ash were better than those for 100% OPC and natural sand

Channel forms recovery in an ephemeral river after gravel mining (Palancia River, Eastern Spain)

During the 1970s, the Palancia River was intensively affected by gravel mining instream. This activity completely destroyed the fluvial forms, devastating the original wandering pattern. At the end of the 1980s, gravel mining ceased and the river started a process of recovery, only altered by several clearing operations. The aim of this work is to describe these processes of change, analyzing the river's morphosedimentary conditions through a GIS analysis of aerial photographs previous to, simultaneous with, and subsequent to the intense gravel mining activity. Results explain the current difficulties of some ephemeral rivers to recover their original forms, because of the sediment and water deficit conditions, the critical role of channel incision and inappropriate actions of river clearing and channelization for flood prevention

Value added utilization of by-product electric furnace ferronickel slag as construction materials: A review

This paper reviews the potential use of electric furnace ferronickel slag (FNS) as a fine aggregate and binder in Portland cement and geopolymer concretes. It has been reported that the use of FNS as a fine aggregate can improve the strength and durability properties of concrete. Use of some FNS aggregates containing reactive silica may potentially cause alkali-silica reaction (ASR) in Portland cement concrete. However, the inclusion of supplementary cementitious materials (SCM) such as fly ash and blast furnace slag as partial cement replacement can effectively mitigate the ASR expansion. When finely ground FNS is used with cement, it shows pozzolanic reaction, which is similar to that of other common SCMs such as fly ash. Furthermore, 20% FNS powder blended geopolymer showed greater strength and durability properties as compared to 100% fly ash based geopolymers. The utilization of raw FNS in pavement construction is reported as a useful alternative to natural aggregate. Therefore, the use of by-product FNS in the construction industry will be a valuable step to help conservation of natural resources and add sustainability to infrastructures development. This paper presents a comprehensive review of the available results on the effects of FNS in concrete as aggregate and binder, and provides some recommendations for future research in this field

Perturbation Analysis of the Conformal Sewing Problem and Related Problems

In this dissertation, we develop two related problems in the nonlinear functional analysis. The first is the analyticity of the Cauchy singular integral in Schauder spaces which is motivated by the second problem, namely the perturbation analysis of the conformal sewing problem in Schauder and Roumieu spaces. In Chapter II, we consider the Cauchy singular integral f (t)φ0 (t) f ◦ φ(−1) (ξ) 1 1 C[φ, f ]( · ) ≡ p. v. dt = p. v. dξ 2πi ∂D φ(t) − φ(·) 2πi φ ξ − φ(·) where the oriented simple closed curve φ and the density function f are both defined on the counterclockwise oriented boundary ∂D of the plane unit disk D. Although the linear operator C[φ, ·], for a fixed φ, and the numerical computation of C[φ, f ] have been extensively studied for the last century, in view to several applications to integral equations and boundary value problems (cf. e.g. Muskhelishvili (1953) and Gakhov (1966)), the analysis of the nonlinear functional dependence of C[φ, f ] upon both its arguments seems to be a subject analyzed only more recently (see Introduction Ch. II). This new subject of research finds application in the nonlinear problems of perturbation nature which involve the Cauchy singular integral. In Chapter II we extend the analyticity result for the operator C[·, ·] of Coifman & Meyer (1983b) to a Schauder spaces setting. We assume that both φ and f belong to a Schauder space, say C∗m,α (∂D, C), of complex-valued function of class C m,α on ∂D, with m a positive natural number and α ∈ ]0, 1[. As it is well-known, under such conditions on φ and f , the function C[φ, f ](·) is also of class C m,α . By proving the unique solvability of a boundary value problem of elliptic nature in D and by applying Implicit Function Theorem to a suitable functional equation, we show the real analyticity of C[·, ·]. Then we show the complex analyticity of C[·, ·] and we compute all its differentials. This result of Lanza & Preciso (1998) will be applied in the second part of this dissertation and in another perturbation problem associated to a nonlinear integral equation (cf. Lanza & Rogosin (1997)). In Chapter III, we introduce the conformal sewing problem associated to a shift φ of ∂D, i.e. a homeomorphism of ∂D to itself. It consists in finding a pair of conformal functions (F, G) defined in D and C \ cl D, respectively, such that their continuous extensions to cl D e C \ D, Fe and G e respectively, satisfy Fe(φ(t)) = G(t) for all t ∈ ∂D. A simple normalization condition and well-known results ensure that the sewing problem associated to φ has a unique solution (F, G) and we denote by (F [·], G[·]) the pair of operators which maps φ to the trace on ∂D of such solution. The regularity properties of the operators F [φ] and G[φ] in spaces of regular functions can be used in the study of Teichmüller spaces, which constitute an important subject in geometric function theory (see Nag (1996)). Our aim is to find natural Banach spaces of regular functions where to obtain the analyticity of F [·] and G[·]. First we study the regularity of such operators in Schauder spaces C∗m,α (∂D, C), with m ≥ 1, α ∈ ]0, 1[. By using the classical integral equation approach to the sewing problem, we show that G[φ] and F [φ] = G[φ] ◦ φ(−1) belong to C∗m,α (∂D, C) when φ belongs to C∗m,α (∂D, C). In this setting, by using the analyticity of the Cauchy singular integral (cf. Ch. II) and by applying Implicit Function Theorem to a suitable integral equation, we show that G[·] extends to a complex analytic operator. Then we prove that this Schauder spaces setting is not sufficient in order to obtain an analytic extension of the operator F [·]. Indeed a natural assumption in order to have F [·] analytic, is that φ belongs to a space of real analytic functions of ∂D to C. In Chapter IV we introduce Banach spaces of real analytic functions, namely the Roumieu spaces associated to the differentiation operator. In this setting we show that G[·] and F [·] can be extended to complex analytic operators by employing the regularity results on the composition and on the inversion operator of Lanza (1994 and 1996b)

Perturbation Analysis of the Conformal Sewing Problem and Related Problems

In this dissertation, we develop two related problems in the nonlinear functional analysis. The first is the analyticity of the Cauchy singular integral in Schauder spaces which is motivated by the second problem, namely the perturbation analysis of the conformal sewing problem in Schauder and Roumieu spaces. In Chapter II, we consider the Cauchy singular integral f (t)φ0 (t) f ◦ φ(−1) (ξ) 1 1 C[φ, f ]( · ) ≡ p. v. dt = p. v. dξ 2πi ∂D φ(t) − φ(·) 2πi φ ξ − φ(·) where the oriented simple closed curve φ and the density function f are both defined on the counterclockwise oriented boundary ∂D of the plane unit disk D. Although the linear operator C[φ, ·], for a fixed φ, and the numerical computation of C[φ, f ] have been extensively studied for the last century, in view to several applications to integral equations and boundary value problems (cf. e.g. Muskhelishvili (1953) and Gakhov (1966)), the analysis of the nonlinear functional dependence of C[φ, f ] upon both its arguments seems to be a subject analyzed only more recently (see Introduction Ch. II). This new subject of research finds application in the nonlinear problems of perturbation nature which involve the Cauchy singular integral. In Chapter II we extend the analyticity result for the operator C[·, ·] of Coifman & Meyer (1983b) to a Schauder spaces setting. We assume that both φ and f belong to a Schauder space, say C∗m,α (∂D, C), of complex-valued function of class C m,α on ∂D, with m a positive natural number and α ∈ ]0, 1[. As it is well-known, under such conditions on φ and f , the function C[φ, f ](·) is also of class C m,α . By proving the unique solvability of a boundary value problem of elliptic nature in D and by applying Implicit Function Theorem to a suitable functional equation, we show the real analyticity of C[·, ·]. Then we show the complex analyticity of C[·, ·] and we compute all its differentials. This result of Lanza & Preciso (1998) will be applied in the second part of this dissertation and in another perturbation problem associated to a nonlinear integral equation (cf. Lanza & Rogosin (1997)). In Chapter III, we introduce the conformal sewing problem associated to a shift φ of ∂D, i.e. a homeomorphism of ∂D to itself. It consists in finding a pair of conformal functions (F, G) defined in D and C \ cl D, respectively, such that their continuous extensions to cl D e C \ D, Fe and G e respectively, satisfy Fe(φ(t)) = G(t) for all t ∈ ∂D. A simple normalization condition and well-known results ensure that the sewing problem associated to φ has a unique solution (F, G) and we denote by (F [·], G[·]) the pair of operators which maps φ to the trace on ∂D of such solution. The regularity properties of the operators F [φ] and G[φ] in spaces of regular functions can be used in the study of Teichmüller spaces, which constitute an important subject in geometric function theory (see Nag (1996)). Our aim is to find natural Banach spaces of regular functions where to obtain the analyticity of F [·] and G[·]. First we study the regularity of such operators in Schauder spaces C∗m,α (∂D, C), with m ≥ 1, α ∈ ]0, 1[. By using the classical integral equation approach to the sewing problem, we show that G[φ] and F [φ] = G[φ] ◦ φ(−1) belong to C∗m,α (∂D, C) when φ belongs to C∗m,α (∂D, C). In this setting, by using the analyticity of the Cauchy singular integral (cf. Ch. II) and by applying Implicit Function Theorem to a suitable integral equation, we show that G[·] extends to a complex analytic operator. Then we prove that this Schauder spaces setting is not sufficient in order to obtain an analytic extension of the operator F [·]. Indeed a natural assumption in order to have F [·] analytic, is that φ belongs to a space of real analytic functions of ∂D to C. In Chapter IV we introduce Banach spaces of real analytic functions, namely the Roumieu spaces associated to the differentiation operator. In this setting we show that G[·] and F [·] can be extended to complex analytic operators by employing the regularity results on the composition and on the inversion operator of Lanza (1994 and 1996b)