Browsing by Issue Date, starting with "2003"
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- Chlormequat selective electrodes: construction, evaluation and application at FIA systemsPublication . Ferreira Sales, Maria Goreti; Lino, Nuno F. M. C.; Paíga, PaulaA flow injection analysis (FIA) system having a chlormequat selective electrode is proposed. Several electrodes with poly(vinyl chloride) based membranes were constructed for this purpose. Comparative characterization suggestedthe use of membrane with chlormequat tetraphenylborate and dibutylphthalate. On a single-line FIA set-up, operating with 1x10-2 mol L-1 ionic strength and 6.3 pH, calibration curves presented slopes of 53.6±0.4mV decade-1 within 5.0x10-6 and1.0x10-3 mol L-1, andsquaredcorrelation coefficients >0.9953. The detection limit was 2.2x10-6 mol L-1 and the repeatability equal to ±0.68mV (0.7%). A dual-channel FIA manifold was therefore constructed, enabling automatic attainment of previous ionic strength andpH conditions and thus eliminating sample preparation steps. Slopes of 45.5±0.2mV decade -1 along a concentration range of 8.0x10-6 to 1.0x10-3 mol L-1 with a repeatability ±0.4mV (0.69%) were obtained. Analyses of real samples were performed, and recovery gave results ranging from 96.6 to 101.1%.
- A Distributed System for the Dissemination of DGPS Data through the InternetPublication . Soares, Manuel Gonçalves; Malheiro, BeneditaIn this paper we describe a low cost distributed system intended to increase the positioning accuracy of outdoor navigation systems based on the Global Positioning System (GPS). Since the accuracy of absolute GPS positioning is insufficient for many outdoor navigation tasks, another GPS based methodology – the Differential GPS (DGPS) – was developed in the nineties. The differential or relative positioning approach is based on the calculation and dissemination of the range errors of the received GPS satellites. GPS/DGPS receivers correlate the broadcasted GPS data with the DGPS corrections, granting users increased accuracy. DGPS data can be disseminated using terrestrial radio beacons, satellites and, more recently, the Internet. Our goal is to provide mobile platforms within our campus with DGPS data for precise outdoor navigation. To achieve this objective, we designed and implemented a three-tier client/server distributed system that, first, establishes Internet links with remote DGPS sources and, then, performs campus-wide dissemination of the obtained data. The Internet links are established between data servers connected to remote DGPS sources and the client, which is the data input module of the campus-wide DGPS data provider. The campus DGPS data provider allows the establishment of both Intranet and wireless links within the campus. This distributed system is expected to provide adequate support for accurate outdoor navigation tasks.
- Gestão do conhecimento: competências para a inovação e competividadePublication . Correia, Ana Maria Ramalho; Mesquita, Anabela
- Explosion of smoothness from a point to everywhere for conjugacies between diffeomorphisms on surfacesPublication . Ferreira, Flávio; Pinto, Alberto A.For diffeomorphisms on surfaces with basic sets, we show the following type of rigidity result: if a topological conjugacy between them is differentiable at a point in the basic set then the conjugacy has a smooth extension to the surface. These results generalize the similar ones of D. Sullivan, E. de Faria and ours for one-dimensional expanding dynamics.
- The home screening questionnaire: A validation studyPublication . Pessanha, Manuela; Bairrão, J.The study analysed the usefulness of the Home Screening Questionnaire (HSQ) as an alternative to the Home Observation and Mesurement of the Environment inventory (HOME). Both are measures of the home enviroment quality. Both measures significantly intercorrelated. It was conclued that the HSQ is an easy to administrate alternative to the HOME inventory
- Improving the learning experience and learning environment of adults in Higher Education – Project LIHE: the Portuguese casePublication . Correia, Ana Maria Ramalho; Mesquita, AnabelaThe promotion of a knowledge-based society needs, on one hand, technological infrastructure and, on the other hand, a workforce with the necessary skills, knowledge and competences, supported by a well-structured initial education and by a continuous learning program. In the last years, Universities have opened their doors to all citizens, regardless of their status or origin, if they have the capacity to benefit from the educational services on offer. This strategy has allowed mature students to enter (or re-enter) the formal higher education system. Although these students may possess a richness of experience, they can also have difficulty in adapting to the pedagogical approaches of learning and teaching and their attitudes and problems are not necessarily the same as those of traditional students. It is in this context that the project LIHE – Learning in Higher Education emerges. In this paper, the background of the project and the most relevant literature for the subject are briefly described. It is followed by a presentation of the project aims, objectives and methodological approaches. The Portuguese case is introduced, together with the results of questionnaires and interviews. Some preliminary conclusions are outlined. Finally, avenues of future research are discussed
- Position/Force control of a walking robotPublication . Silva, Manuel; Tenreiro Machado, J. A.; Lopes, António M.This paper analyzes the performance of a classical position PD algorithm and a new cascade controller, involving position and force feedback loops, for multi-legged locomotion systems. For that objective the robot prescribed motion is characterized in terms of several locomotion variables. A group os indices measures the walking performance based on the robot and terrein dynamical properties and on the robot hit trajactories. A set of experiments reveals the performance of the control architectures in the viewpoint of the proposed indices.
- Estruturação e representação gráfica de sistemas conceptuais. Uma abordagem no subdomínio da mortalidadePublication . Silva, ManuelEstruturação e representação gráfica de sistemas conceptuais. Uma abordagem no subdomínio da mortalidade
- Le développement des compétences (méta) linguistiques dans le curriculum du préscolairePublication . Ribeiro, Deolinda; Pinto, F.
- Knowledge magement: a rewarding challenge for SME's?Publication . Mesquita, Anabela; Correia, Ana Maria Ramalho