Browsing by Issue Date, starting with "2011-06"
Now showing 1 - 10 of 19
Results Per Page
Sort Options
- Effect of relative sediment size on clear-water equilibrium scour depth at single cylindrical piersPublication . Lança, Rui; Fael, Cristina; Cardoso, AntónioExperiments on local scouring around cylindrical piers were performed in steady clear-water conditions to investigate the effect of sediment size, D50, on equilibrium scour depth, dse. Thirteen experiments, run for 7 to 13 days, were carried out. The dependence of the normalized equilibrium scour depth, dse/Dp, on the relative sediment size, Dp/D50, was identified, corroborating the findings of Sheppard et al. (1995; 1999; 2004). Contrarily to consecrated literature and associated practice, it was observed that the normalized equilibrium scour depth decreases with the relative sediment size, for Dp/D50 > ~100. This effect is possibly one of the causes of frequently reported over prediction of scour by formulas established on the basis of laboratory studies, where frequently Dp/D50 < 100.
- Genealogia dos conceitos em educação de adultos: da educação permanente à aprendizagem ao longo da vida - um estudo sobre os fundamentos politico-pedagógicos da prática educacionalPublication . Barros, RosannaEste livro, intitulado Genealogia dos Conceitos em Educação de Adultos: da Educação de Permanente à Aprendizagem ao Longo de uma Vida. Um Estudo sobre os Fundamentos Político-Pedagógicos da Prática Educacional, da autoria de Rosanna Barros, consiste numa publicação que procura responder a dois grandes propósitos. Um primeiro liga-se ao estabelecimento de um "mapa", como refere a autora, de alguns conceitos essenciais para compreender a educação de adultos. Numa abordagem analítica, são apresentados e discutidos instrumentos teóricos que facilitam a interpretação de diversos domínio da educação de adultos, como a educação, a formação, a aprendizagem e o desenvolvimento, bem como a reflexão sobre as relações que se estabelecem entre educação e aprendizagem, sendo neste caso central o debate sobre conceitos de adulto e de experiência.
- Towards integrating rural vernacular settlements in urban regions: a study of Algarve, PortugalPublication . Costa, Miguel Reimão; Batista, DesidérioThis paper deals with the vernacular settlements that often exist in the fringes of urban centres and their adaptations and absorptions within the expansions of the urban regions. In many parts of the world, the processes of urban expansions that began with the industrial revolution often led to the integration of rural settlements previously located in the outer rings of cities through adaptations that naturally took place at that time. In the recent decades however, this has become more arbitrary and in many cases have led to the loss of value of agricultural land, vernacular settlements and buildings of significant heritage values. Antagonisms have developed between the urban and rural areas and the value of vernacular settings have played little role in urban metropolitan planning. Studies of such situations can reveal how vernacular buildings and hamlets could be integrated to urban areas with appropriate development techniques. In such situations, the rural vernacular buildings and settings need to be protected; enabling them to acquire in the diffuse cities the significance that the historic centers achieved in the traditional compact cities, especially in the second half of the twentieth century. In fact, if the conventional antagonism between city and country had become less significant, the vernacular patrimony – as the ecological systems or the old rural paths and property structure – has to be considered as core considerations in urban planning. This paper argues, in this context, that one should make a distinction between the dispersion patterns and the agglomeration patterns in that they raise different questions in the land use transformations. In order to facilitate the integration of peri-urban vernacular values in metropolitan contexts, it proposes an urban development model based on heritage and landscape which assumes the relevance of appropriating the ecological and cultural structure of landscape as a basic concept of urbanization. To understand some of the issues inherent in this process, the paper looks at the lower Algarve in southern Portugal. The vernacular settlements in this area becomes important due to the fact that the present regional and municipal plans constrain the building process outside the compact urban areas to those existing rural settlements in its fringe areas.
- A importância da coopetição no sector turísticoPublication . Almeida, ClaudiaO actual ambiente empresarial apresenta novos desafios diários aos gestores. A concorrência aguerrida na procura da melhor posição no mercado foi durante muitos anos a principal estratégia das organizações. No entanto, as novas regras do mercado aliadas às inovações tecnológicas e novas formas de comunicação tornaram-se rapidamente em factores chave a ter em consideração na delineação de estratégias, pelo que actuar de forma isolada deixou de ser uma vantagem para passar a ser uma estratégia de menor impacte no sector onde a organização opera. Cada vez mais se assiste a fusões, alianças e acima de tudo a trabalho conjunto entre concorrentes que ao cooperarem entre si conseguem atingir novos mercados, criando sinergias competitivas entre si. Esta estratégia denominada de coopetição tem sido amplamente estudada por vários autores, que avaliaram diferentes sectores de actividade. O presente artigo visa focar esta estratégia e a sua importância no sector da imobiliária residencial-turística, que se apresenta como um sector complexo e que integra uma cadeia de valor com diversos actores de distintas áreas de negócio. Os dados apresentados resultam de uma tese de doutoramento que analisou com mais detalhe este sector de actividade no Algarve.
- Knowledge management in tourism organisations: proposal for an analytical modelPublication . Sequeira, Bernardete; Marques, João FilipeTourism is an activity-based service sector in which information and knowledge are fundamental to developing realistic strategies and business plans. This article presents a model that was developed in an investigation called “Organisational Knowledge Management in Tourism Organisations,” which was part of a doctoral degree in Sociology, Faculty of Economics, University of Algarve. This study investigated how Algarve tourist organisations manage knowledge by observing how they create, retain, share and use it. This empirical research is based on a study of three cases that used documental investigation, interviews and questionnaires and the analytic model that is introduced here. We present an analytic model that identifies the different stages of knowledge management (acquisition / knowledge creation, retention / storage, transfer / sharing and use) and the management practices that facilitate it (strategic management, organisational culture, structure and work processes, human resource policies, information systems and communications, evaluation of results and relationship with the environment outside the organisation) based on learning promotion.
- Expression and trans-specific polymorphism of self-incompatibility RNases in Coffea (Rubiaceae)Publication . Nowak, Michael D.; Davis, Aaron P.; Anthony, Francois; Yoder, Anne D.Self-incompatibility (SI) is widespread in the angiosperms, but identifying the biochemical components of SI mechanisms has proven to be difficult in most lineages. Coffea (coffee; Rubiaceae) is a genus of old-world tropical understory trees in which the vast majority of diploid species utilize a mechanism of gametophytic self-incompatibility (GSI). The S-RNase GSI system was one of the first SI mechanisms to be biochemically characterized, and likely represents the ancestral Eudicot condition as evidenced by its functional characterization in both asterid (Solanaceae, Plantaginaceae) and rosid (Rosaceae) lineages. The S-RNase GSI mechanism employs the activity of class III RNase T2 proteins to terminate the growth of "self" pollen tubes. Here, we investigate the mechanism of Coffea GSI and specifically examine the potential for homology to S-RNase GSI by sequencing class III RNase T2 genes in populations of 14 African and Madagascan Coffea species and the closely related self-compatible species Psilanthus ebracteolatus. Phylogenetic analyses of these sequences aligned to a diverse sample of plant RNase T2 genes show that the Coffea genome contains at least three class III RNase T2 genes. Patterns of tissue-specific gene expression identify one of these RNase T2 genes as the putative Coffea S-RNase gene. We show that populations of SI Coffea are remarkably polymorphic for putative S-RNase alleles, and exhibit a persistent pattern of trans-specific polymorphism characteristic of all S-RNase genes previously isolated from GSI Eudicot lineages. We thus conclude that Coffea GSI is most likely homologous to the classic Eudicot S-RNase system, which was retained since the divergence of the Rubiaceae lineage from an ancient SI Eudicot ancestor, nearly 90 million years ago.
- Alternative codends to reduce bycatch in Chilean crustacean trawl fisheriesPublication . Queirolo, Dante; Erzini, Karim; Hurtado, Carlos F.; Ahumada, Mauricio; Soriguer, M. C.This study was conducted to determine the reduction in bycatch and the loss of target catch in trawl hauls for three commercial crustacean species (yellow squat lobster, Cervimunida johni, nylon shrimp, Heterocarpus reedi, and red squat lobster, Pleuroncodes monodon) in central Chile. Two experiments were carried out using the covered codend method; the first used different mesh sizes (56 and 70 mm, knot-centre to knot-centre) and shapes (diamond and square), and the second tested different reduction devices (escape panel and sorting grid). We analysed the escape proportions of the species caught and the size frequency distributions of the target species and Chilean hake (Merluccius gayi), the main commercial bycatch species. The results demonstrate that it is feasible to significantly reduce bycatch while keeping losses within acceptable ranges. In particular, the best option for yellow squat lobster was the combination of a 70-mm diamond mesh with an escape panel that reduced non-target and target catches by 48% and 7%, respectively. For nylon shrimp, the best option was the use of a 56-mm diamond mesh with a sorting grid that reduced non-target and target catches by 41% and 11%, respectively. Although the results for red squat lobster were not as promising, they will help to guide future research.
- On the usage of the particle velocity field for bottom characterizationPublication . Felisberto, P.; Rodríguez, O. C.; Santos, P.; Jesus, S. M.Vector sensors (VS) are devices that measure the vectorial particle velocity field. Compared with traditional hydrophone arrays that measure the acoustic pressure, systems based on VS present enhanced spatial filtering capabilities. The feasibility of bottom characterization with a 4-element 40cm length vector sensor array (VSA) in a frequency band of 8-14 kHz was recently demonstrated by Santos et al. The study suggests that systems based on VS outperform traditional hydrophone arrays, when considered in geoacoustic parameter estimation. Vector sensor data can improve the resolution of the estimators, moreover the highest resolution of the estimates were achieved with the vertical particle velocity measurements alone. Bearing in mind that actually VS are not widely available, the present work shows through simulations that using a narrow band signal and a vertical array which elements are pairs of hydrophones one can estimate the vertical particle field and attain a resolution for the bottom parameters similar to that obtained by a VSA. Based on a normal mode description of the pressure and particle velocity field, the resolution gain achieved by a linear estimator based on the vertical component only, is compared with similar estimators based on the pressure or on the horizontal component. Using simulations for different shallow water typical scenarios, we point out sensible values for the number of sensors, inter sensor spacing for system design as well as preferred equipment location for best results. This work is a contribution to the design of a compact array of hydrophones that takes advantage of the higher sensitivity of the vertical particle velocity field for geoacoustic parameter estimation.
- How economic crisis is affecting firms? Building resilience capacity through innovationPublication . Fernandes, Silvia Brito; Liebenstein, AntonMore than ever firms will be required to develop strategies for coping with future shocks and stresses to our economic and social infrastructures. They will need to build the so called resilience capacity, which is an umbrella term for the planning and design strategies that help firms to develop the necessary capacity to meet challenges. The present paper, based on an assessment of works that explore recent European reports on innovation performance, discusses some underling effects of the economic crisis. This discussion reveals the main differentiating impacts of a major downturn on innovation behavior. Some of the conclusions acknowledge that firms will have to find new ways to reduce their risk-averse dependency and become more flexible. To become more resilient, firms will need to adopt planning and design strategies that allow them to develop the capacities to better respond and adapt to the emerging economic and social stresses. Developing these capacities will involve firms in a complex web of planning and development decisions that, in combination, must be designed to transform our current economic systems into much more flexible and dynamic ones. Small and medium enterprises are more exposed to high competitive pressures. Thus, they have to search for new business opportunities. The choice of sectors and the design of public procurement policies can provide new opportunities and it is very likely that those that manage to capture them will be the winners. With the polarization of innovation and knowledge creation across Europe, a few countries are responsible for the bulk of innovation and knowledge production. The technology gap provides a fundamental potentiality for lagging behind countries to catch-up. However, there is a general fragility as major effects of the crisis have shown. Therefore, a more articulated policy needs to be put in practice as suggested and more attention should be given to investment in knowledge diffusion and absorption depending on the specific national context. The fact that some structural characteristics of the national innovation system explain persistency of innovation in response to major exogenous shocks sheds some light on the behavior of firms during crisis. This represents a step forward in terms of understanding the mechanisms underlying the relationship between macro and micro-determinants of innovation.
- Probe timing optimization for time-reversal underwater communicationsPublication . Silva, A.; Jesus, S. M.; Gomes, J. P.Passive Time Reversal (pTR) is one of the variants of time reversal applicable to digital underwater communications. In passive time reversal a probe-signal is transmitted ahead of the data-signal in order to estimate the channel impulse response for later use as a replica signal in a time reversal mirror fashion. In practice the received probe-signal must be captured in a time-window and, after correlation with the transmitted probesignal, give a noisy estimation of the channel impulse response. Therefore, the output Signal to Noise Ratio (SNR), the Inter- Symbolic Interference (ISI) and the detection rate of passive time reversal will strongly depend on the starting time and duration of such time-window. Typically the beginning and the duration of that time-window should depend on the travel time and the dispersion of the acoustic channel. In this paper, the maximization of the pTR output SNR relative to the probe time-window is derived in closed form. It will be shown that the probe timing that gives the lower detection error rate can be predicted using closed form metrics for the pTR output SNR and ISI. Theoretical results are found to be in full agreement with simulations and with results obtained on experimental data taken during the INTIFANTE’00 sea trial.