A Multi-Level Representation of f0 using the Continuous Wavelet Transform and the Discrete Cosine Transform

We propose a representation of f0 using the Continuous Wavelet Transform (CWT) and the Discrete Cosine Trans-form (DCT). The CWT decomposes the signal into various scales of selected frequencies, while the DCT compactly represents complex contours as a weighted sum of cosine functions. The proposed approach has the advantage of combining signal decomposition and higher-level represen-tations, thus modeling low-frequencies at higher levels and high-frequencies at lower-levels. Objective results indicate that this representation improves f0 prediction over tradi-tional short-term approaches. Subjective results show that improvements are seen over the typical MSD-HMM and are comparable to the recently proposed CWT-HMM, while us-ing less parameters. These results are discussed and future lines of research are proposed. Index Terms — prosody, HMM-based synthesis, f0 mod-eling, continuous wavelet transform, discrete cosine trans-form 1

The LSTS open-source communication and autonomy software: enabling networked vehicle systems to find track, and sample dynamic features of the ocean

Peer Reviewe

As assimetrias regionais em Portugal : análise da convergência versus divergência ao nível dos municípios

Há muito que a literatura empírica sublinha a realidade socioeconómica assimétrica que Portugal apresenta, contrastando sobretudo litoral e interior, mas também “Norte” e “Sul”. A presente comunicação analisa a evolução das assimetrias ao nível dos municípios do país. Na análise da convergência a que se procedeu usou-se como proxy do nível de bem-estar ou de desenvolvimento dos municípios o Indicador per capita de Poder de Compra (IpcPC) no período 1995-2009. A técnica de análise utilizada foi do tipo seccional, recorrendo ao método de estimação dos mínimos quadrados ordinários. Testa-se quer a convergência sigma (σ), que se manifesta através na diminuição da dispersão do rendimento entre as diferentes regiões ao longo do tempo, quer a convergência beta (β), em que se avalia a existência de uma correlação negativa entre o ritmo de crescimento de uma região e o seu estado de desenvolvimento inicial. Os resultados alcançados sugerem que: i) persistem divergências de desenvolvimento acentuadas entre os vários municípios portugueses; ii) no período em análise, se verificou convergência, quer absoluta, quer condicionada, entre os municípios; iii) é na convergência condicionada que se obtêm os resultados mais robustos.COMPETE; QREN; FEDER; Fundação para a Ciência e a Tecnologia (FCT

Evaluation of functionally graded ceramic crucible for induction melting of TiAl based alloys

During the last years a very significant effort to develop a melting crucible for induction melting of Ti based alloys at competitive cost has been carried out by many researchers, where the authors are included. Results obtained so far have shown that no material accomplishes the melting crucibles two main demands: inertness facing titanium alloys and suitable/enough thermal-shock resistance. Until now, yttrium and calcium oxides were those materials that performed best on what concerns to thermodynamic stability. However, in both cases, crucibles thermal-shock resistance was very poor, and there are references to crucibles that cracked during melting. Besides, calcium oxide reveals manipulation problems, due to its high higroscopicity. This paper concerns to the evaluation of zircon based crucibles with Y2O3 inner layer for induction melting of TiAl based alloys. A novel multi layered crucible production technique based in a centrifugally assisted slip casting process followed by a sintering operation is described, and results concerning to crucibles porosity and wall composition and morphology are presented. Crucibles obtained in different processing conditions were used to melt a Ti48Al alloy which was poured in graphite moulds. Experimental results include alloy chemical contamination with residual elements, mainly yttrium and oxygen, microhardness measurement and the presence of yttrium oxide and zircon inclusions in the cast samples. Results concerning to the crucibles behaviour are also presented with particular attention to cracks development. The Y2O3 crucible layer was found to suffer some erosion and be slightly dissolved by the molten alloy and the extent of those phenomena depends on the porosity of the layer surface, for fixed experimental melting conditionsFCT - Fundação para a Ciência e Tecnologi

Aluminium evaporation during ceramic crucible induction melting of titanium aluminides

Melting TiAl based alloys in ceramic crucibles often leads to chemical contamination, alloy heterogeneity and non-metallic inclusions. The severity of such phenomena usually depends on the nature of crucible materials, the melting stock composition and the melting parameters, namely superheating time and temperature and melting pressure. Among the referred drawbacks, Al loss during melting is a critical aspect, as its concentration in TiAl based alloys has a very strong effect in their mechanical properties. Although a few studies of critical factors affecting the evaporation behaviour of Al during electron beam and induction skull melting of Ti-Al alloys had been carried out, until now no information was released on this subject for the ceramic crucible induction melting process. In this work a Ti-48Al alloy was induction melted in a zircon crucible with Y2O3 inner layer, using 50 and 100 ºC superheating temperatures and 0, 60 and 90 second holding times, and poured into a graphite mould. The effect of different temperature/time combinations in the alloy composition, Al loss by evaporation and extent of the metal/crucible interaction was studied for different melting pressures. Al loss was found to increase significantly for melting pressures below around 10-1 mbar, at a rate that increases as melting pressure decreases, until a maximum rate is reached, remaining constant for lower pressure levels. Metal/crucible interaction increased directly with the melting pressure and superheating time, leading to alloy contamination with yttrium and oxygen. For the experimental set-up and conditions used on this work, optimal superheating time/pressure combinations that lead to acceptable alloy composition and sanity have been identified.FCT - Fundação para a Ciência e Tecnologi

Glasses and glass-ceramics of the system CaO-MgO-Al2O3-SiO2 obtained from natural sedimentary raw materials

Common and low-cost natural sedimentary raw materials such as ball clay, dolomite, quartz sand and diatomite were used as the main constituents for the production of glasses and glass-ceramics of the system CaO-MgO-Al2O3-SiO2. The crystallization of the glassy batch was promoted by the addition of a nucleation agent (TiO2). The crystallization sequence was examined by DTA, XRD, SEM, and thermal expansion analyses. Wollastonite and diopside are the main phases detected and the amount and grain size/shape of crystals were found to be strongly dependent on titania additions and on the annealing conditions. The characterization of relevant functional parameters of glass and glass-ceramic samples revealed interesting results

Characterization of Al2O3 and SiO2 ultra thin-films deposited by ALD for microfabricated rubidium vapor cells

The Atomic Layer Deposition (ALD) technique can be used to increase the lifetime of microfabricated rubidium vapor cells (magnetic sensors for magnetoencephalography) by an ultra-thin coating layer deposited on the internal cell walls (Figure 1). The ALD presents excellent control over the ultra thin films thickness (< 20 nm) and allows complex 3D structures to be covered with a high-aspect-ratio coating. This work shows the characterization of alumina (Al2O3) and silicon dioxide (SiO2) ultra-thin films deposited by Thermal ALD (ThALD) and Plasma-Enhanced ALD (PEALD).This work was supported by: project MME and FCT with the project MPhotonBiopsy, PTDC/FIS-OTI/1259/2020, Infrastructures Micro&NanoFabs@PT, reference NORTE-01-0145-FEDER-022090, POR Norte, Portugal 2020

Fish assemblages of shallow intertidal habitats of the Ria Formosa lagoon (South Portugal): influence of habitat and season

Fish assemblages in seagrass and unvegetated habitats located in shallow intertidal creeks within the saltmarsh area of the Ria Formosa coastal lagoon were sampled with a Riley push net at 3 sites on a monthly basis over a 1 yr period. The objective was to test if both habitats support similar fish assemblages in terms of abundance, diversity, assemblage structure, and size distribution, and to investigate how site and season affect the assemblages. Fish assemblages associated with these habitats were significantly different in terms of diversity, abundance, and assemblage structure. Seagrass supported a larger number of species and greater diversity, while unvegetated habitat supported greater fish numbers but only of a few species. The habitats were dominated by different groups of resident species that were responsible for major differences in fish assemblage structure between habitats. Pomatoschistus microps and young-of-the-year (YOY) Atherina presbyter dominated the unvegetated habitat, while seagrass was dominated by a diverse group of species, in particular syngnathids and small labrids, revealing different habitat preferences. Site and season were determinant factors conditioning the role of habitat in structuring fish assemblages. Distance between habitats, site elevation, and the amount of marsh drained affected fish assemblages in both habitats. Seasonal fluctuations in the presence and abundance of YOY from marine migrant and resident species were responsible for comparable changes in fish assemblage structure in both habitats. Both habitats provide a distinctive nursery area for different species, while common species reveal ontogenic distributional changes between habitats, where smaller fish appear first in unvegetated creeks