Scour around marine foundations in layered sediments: a mathematical modelling approach

In order to improve the understanding of scour processes in layered conditions for offshore foundations, a laboratory study was conducted regarding equilibrium scour depth vs. time curve and its adjustment to hyperbolic and exponential/linear combined functions. The present paper provides a mathematical study describing a set of scour tests in order to clarify the scour depth evolution for complex, non-cohesive soil configurations

Brief review on the limit state function of dynamic scour protections

Offshore foundations, namely for offshore wind, wave and tidal applications, often require the use of scour protections. Rip-rap scour protections are an important element of the foundation to ensure that the natural frequency stays within the design limits. Scour protection design still presents a remarkable empirical nature, which typically leads to uncertainty on their behaviour under extreme met-ocean conditions. Therefore, reliability assessment of scour protections has been seen as a possibility to account for design uncertainty and to optimise the scour protections. However, the definition of a suitable limit state function is still a matter of research focus, namely, regarding the proper definition of the acceptable damage level for dynamic scour protections. This research provides a brief review on the recent studies related to both the limit state function and the calculation of damage numbers through bathymetric data. A discussion is raised on how the methodologies for calculating the damage number may influence the limit state function and a theoretical example is given to assess the effects on the probability of failure. Results have shown that the acceptable damage number requires a clearer definition, which should be based on the number of layers of rock material and the area of filter exposure. In addition, this research highlights the need for alternative ways to assess damage

Influência do atrito das defensas no comportamento de um navio amarrado para diferentes níveis de pré-tensão nos traveses

Nesta comunicação analisa-se a influência do coeficiente de atrito na interface do casco do navio com as defensas, no comportamento de um navio petroleiro amarrado, para duas condições de pré-tensão nos cabos de amarração. A análise é efectuada com base nos resultados de testes em modelo físico do comportamento de um navio amarrado no Posto "A" do Terminal de Petroleiros do Porto de Leixões. Esses testes foram realizados com dois modelos físicos construídos à escala geométrica 1/100. O primeiro corresponde a uma reprodução simplificada do Posto "A" e área envolvente, com o modelo do navio a ser ensaiado, exclusivamente, para ondas de vante. O segundo procura reproduzir as características do protótipo com maior rigor, e inclui o quebramar Norte (ou exterior), o molhe Sul, o antigo quebramar Norte (estrutura centenária), e uma extensão significativa da praia de Matosinhos

Physical modeling of sand-filled geosystems for coastal protection

Unidirectional irregular waves of varying significant wave-height and peak period but with aconstant spectral shape (JONSWAP spectrum, =3.3) were generated over a sandy 3:20 sloped planebeach to investigate scour fronting a dune erosion control system constructed from geotextiles, slopeinclined at 45º. Both passive (i.e., three dune erosion control systems with two configurations) and active(i.e., one nearshore submerged structure with four configurations) structures are investigated. A twodimensionalphysical movable-bed model simulating the prototype dune-beach systems of Estela, locatedalong the NW Portuguese coast, is employed in this study. The paper presents a brief characterization ofthe prototype conditions and discusses requirements and limitations on the choice of model scale for thewaves, the sediments, and the geotextile materials

Critérios de selecção de brocas de osteotomia em cirurgia oral

info:eu-repo/semantics/publishedVersio

A high resolution geospatial database for wave energy exploitation

The estimation of energy production of a given WEC (wave energy converter) at a given coastal site is thebasis for correct decision-making regarding wave energy exploitation in a coastal region. Nevertheless,the procedure followed by the conventional approach to characterize the wave energy resource does notprovide the required information to obtain an accurate estimate. In this work, this information is providedfor the region with the greatest resource in the Iberian Peninsula, the Death Coast (NW Spain). Forthis purpose, a geospatial database is produced by using a methodology which involves the considerationof virtually the totality of the resource together with the implementation of a high resolution spectralnumerical model. In addition, a Matlab-based toolbox called WEDGE (Wave Energy Diagram GEnerator)is implemented to access the database and automatically generate high resolution energy diagrams (orcharacterization matrices) of the wave energy resource at any coastal location within this region. In thisway, a precise computation of energy production of any WEC at any site of interest can now be performed.Finally, the functionality of the database is shown through a case study of a recently proposedwave farm

Exploración vocacional en adolescentes: evaluación de una intervención en clase

Analisa-se o impacto de uma intervenção psicológica na exploração e tomada de decisão vocacional em adolescentes portugueses. Em contexto curricular e de classe, desenvolveram-se actividades de exploração do meio e do Eu com 39 alunos e 43 alunas do 9o ano, entre 13 e 17 anos (M=14,4, DP=0,95). Em um design pré/pós-teste, aplicaram-se o Career Exploration Survey (CES) e o Career Decision Difficulties Questionnaire (CDDQ). Os resultados do teste do sinal evidenciaram ganhos significativos (p<0,01) nas dimensões de exploração e diminuição significativa da falta de informação profissional (p<0,01) e do total das dificuldades de decisão (p<0,05). Observou-se um padrão de correlações negativas (ró de Spearman) entre as duas medidas vocacionais, evidenciando uma relação entre a informação explorada na intervenção e a diminuição das dificuldades de decisão por falta de motivação. Em geral, os resultados suportam a importância do papel da exploração da carreira na diminuição das dificuldades de tomada de decisão.This study analyses the impact of a psychological intervention to promote vocational exploration and decisionmaking in Portuguese adolescents. Activities to foster exploration of self and environment were developed in a classroom program with 39 boys and 43 girls, all 9th grade students, between 13 and 17 years of age (M=14,4, SD=0.95). Following a pre/post-test design, the Career Exploration Survey (CES), and the Career Decision Difficulties Questionnaire (CDDQ) were administered. Results of sign-test showed significant increments (p<0.01) in all of the exploration dimensions, significant reduction of lack of occupational information (p<0.01) and of the total of career decision-making difficulties (p<0.05). Negative correlations (Spearman’s rho) between the two career measures was observed, evidencing a relationship between information explored during intervention and decreased difficulty with decision-making due to lack of motivation. In general, results support the importance of career exploration on diminishing decision-making difficulties.Evalúa-se el impacto de una intervención psicológica que fomenta la exploración y la decisión vocacional en adolescentes portugueses. Fueran efectuadas actividades de exploración del medio ambiente y del yo en contexto curricular de clase con 39 alumnos y 43 alumnas del curso 3º ESO, 13 hasta 17 años (M=14,4, DP=0,95). Utilizó-se un diseño pre/posteste, con aplicación del Career Exploration Survey (CES) y Career Decision Difficulties Questionnaire (CDDQ). Resultados del test del señal evidencian beneficios significativos (p<0,01) en las dimensiones de la exploración, reducción significativa de ausencia de información ocupacional (p<0,01) y total de dificultades de decisión (p<0,05). Ha sido observado un patrón de correlaciones negativas (ró de Spearman) entre las dos medidas vocacionales, mostrando relación entre la información explorada e la disminución de las dificultades de decisión por falta de motivación. En general, resultados sostienen la importancia de la exploración de carrera en la disminución de las dificultades de decisió