Browsing by Issue Date, starting with "2008-01"
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- Que publicidade contra a crise?Publication . Verissimo, JorgeEstamos oficialmente em crise. Oficialmente, porque antes deste solene anúncio já estávamos. Basta prestar um pouco de atenção ao “sobe e desce” constante do valor das acções nas bolsas e à redução do investimento publicitário, para constarmos este estado da economia. Perante esta situação de crise qual o papel das empresas? Desinvestir em comunicação? Despedir pessoal? Reduzir as remunerações? Incrementar as promoções? Ser mais agressivo? Fechar a porta? Ou encontrar alternativas?
- Studies towards the living polymerisation of phenylethynyl-calix[4]arene compounds with rhbased ternary catalytic systemsPublication . Costa, Alexandra I.; Prata, José V.The living polymerisation of mono and difunctional phenylethynylcalix[4]arene compounds 1 and 2 by Rh(I) ternary catalytic systems (TCS) was examined. Two TCS were tentatively prepared in situ, adapting known methodologies: (1) Rh(CuCPh)(norbornadiene)(PPh3) and (2) Rh(C(Ph)CvCPh2)(norbornadiene)(PPh3). Using the first TCS, the conjugated polymers poly 1 and poly 2 could be obtained in very good yields (77–86%), in short reaction times and freed from low-molecular-weight products, only when NEt3 was used as a co-catalyst. With the second TCS, excellent results were obtained. Indeed,thiscatalyticsystemprovedtobequiteefficientin thepolymerisation ofcalix[4]arenes 1and 2, affording the correspondent poly 1 and poly 2 essentially in almost quantitative yields (by GPC analysis), under appropriate conditions. The living nature of the polymerisation has been proved. For instance, in the case of calix[4]arene 1, the Mn of the polymer obtained at high monomer conversion increased proportionally with the [1]:[Rh] molar ratio in the feed, keeping [1]o constant, thus showing that irreversible chain transfer or termination reactions did not occur to a major extent. Under the most favourable conditions {[1]:[Rh] 5 50 and [2]:[Rh] 5 50}, the polydispersities of poly 1 and poly 2 were kept in a narrow range (1.16–1.30).
- Mechanical performance of lap joints of flat roof waterproofing membranesPublication . Gonçalves, M.; Lopes, Jorge; Brito, J. de; Lopes, G. A.The roof is the building’s outer envelope element responsible for guaranteeing the upper tightness of the living space. Its function is complex and important since environmental agents act more directly and intensely in it than in any other envelope element. Rain, for example, has a direct impact on roofs and is capable, especially in flat roofs, of leading to dampness manifestations in buildings. Consequently, it can lead to anomalies capable of putting at risk total fulfillment of the most basic dwelling demands. Nevertheless, because flat roofs have functional and formal characteristics that in many cases recommend or even impose their choice, there is a recognizable need for discussing, clarifying, and disseminating design solutions, compositions, and construction detailing of waterproofing systems that, by using new materials and execution techniques, may lead to a good functional performance. Roofs waterproofing materials and the systems they constitute are diverse, and their classification can be established according to different criteria: functionality, raw materials nature, traditional or nontraditional character of the solution, execution technique, and bonding system to the substrate and composition.
- Multi-agent platform for Fault Tolerant Control SystemsPublication . Mendes, Mário J. G. C.; Santos, Bruno M. S.; Costa, José Sá daThis paper proposes a new multi-agent platform for Fault Tolerant Control (FTC) Systems. Several multi-agent platforms exist to deal with different problems but none of them to deal with control systems tolerant to faults using the Matlab/Simulink environment, which is in our days the scientific bench to this kind of research. When dealing with large-scale complex networked control systems (NCS),designing FTC systems is a very difficult task due to the large number of sensors and actuators spatially distributed and network connected. To solve this issue, the FTC platform presented in this paper uses simple and verifiable principles coming mainly from a decentralized design based on causal modelling partitioning of the NCS and distributed computing using multiagent systems paradigm, allowing the use of agents with well established FTC methodologies or new ones developed taking into account the NCS specificities.
- Experimental Results for the Rheological and Rheo-Optical Behavior of Poly(ethylene terephthalate)/ Liquid-Crystalline Polymer BlendsPublication . Cidade, M. T.; Menon, A. R.; Leal, Catarina R.; Pillai, C. K. S.The use of thermoplastic/liquid-crystalline polymer (LCP) blends is recognized as a good strategy for reducing viscosity and improving mechanical properties relative to pure thermoplastics. This improvement, how ever, is only noticeable if the LCP fibrillates, in situ, during processing and the fibrils are kept in the solid state. In this article, we report a morphological, rheological, and rheo optics study performed with two blends of poly(ethylene terephthalate) with a LCP, Rodrun LC3000 (10 and 25 wt % LCP content), and we show that the obtained droplet shape relaxation time (the time the deformed droplet took to regain its spherical form after the cessation of flow) allowed for the explanation of the morphological observa tions. In fact, the droplet-shape relaxation time was higher for the blend with higher LCP content, for the higher experimentally accessible shear rates, and still increased at the highest shear rate, which explained the fibrils of the LCP dispersed phase observed in this blend, whereas for the lower LCP content blend, the droplet-shape relaxation time reached a low-value plateau for higher shear rates, which explained the absence of fibrillation in this blend.
- A importância do conceito de comunicação da escola sociológica de Chicago para os estudos de comunicação e mediaPublication . Subtil, Filipa Mónica de Brito GonçalvesApesar do tópico da comunicação ter ganho estatuto intelectual no pensamento moderno e na pesquisa social através da escola sociológica de Chicago, os estudos da comunicação e dos media tendem a negligenciar, salvo raras excepções, esse valioso contributo. Esta comunicação apresenta o modo como James Carey, um dos mais influentes pensadores americanos dos media e do jornalismo da segunda metade do século XX, considerou, discutiu e incorporou criticamente a reflexão sobre comunicação da escola de Chicago. Carey questiona a história “standard” da investigação em comunicação de massas, confinada ao paradigma funcionalista e empirista da communication research, defendendo a importância de reconsiderar a concepção argumentativa, cívica e universalista da comunicação que foi legada por teóricos como Dewey, Cooley, Mead e Park. Na primeira parte da apresentação mostra-se como Carey recupera e reelabora esta noção para argumentar que a comunicação é algo mais do que transmissão de sinais e signos. Apoiando-se na tradição de Chicago, define a comunicação como uma experiência de vida baseada nas qualidades humanas da intimidade, da conversação e do entendimento que irrompe da experiência partilhada. Em segundo lugar, apresenta-se a crítica de Carey às características utópicas desta tradição, em particular a excessiva expectativa nas tecnologias da comunicação para melhorar a qualidade da cultura e da vida cívica. Por último, aborda-se a forma como Carey recupera o conceito sociológico de comunicação de Chicago para o confrontar com a concepção técnica de comunicação que marca a actual indústria dos media, mostrando como a comunicação perdeu a sua dimensão de comunhão e partilha e se enredou definitivamente num universo de estratégias económicas e políticas sofisticadas.