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Vila Real de Santo António, Portugal

Filipe V.,CIDESD | Fernandes F.,UTAD | Fernandes H.,UTAD | Sousa A.,CITAB | And 2 more authors.
Procedia Computer Science | Year: 2012

This paper presents a system which extends the use of the traditional white cane by the blind for navigation purposes in indoor environments. Depth data of the scene in front of the user is acquired using the Microsoft Kinect sensor which is then mapped into a pattern representation. Using neural networks, the proposed system uses this information to extract relevant features from the scene, enabling the detection of possible obstacles along the way. The results show that the neural network is able to correctly classify the type of pattern presented as input.

Fangueiro D.,University of Lisbon | Ribeiro H.,University of Lisbon | Coutinho J.,Dep Biology and Environment | Cardenas L.,North Wyke Research | And 4 more authors.
Biology and Fertility of Soils | Year: 2010

The following six pig slurries obtained after acidification and/or solid/liquid separation were used in the research: original (S) and acidified (AS) pig slurry, nonacidified (LF) and acidified (ALF) pig slurry liquid fraction, and nonacidified (SF) and acidified (ASF) pig slurry solid fraction. Laboratory incubations were performed to assess the effect of the application of these slurries on N mineralization and CO2 and N2O emissions from a sandy soil. Acidification maintained higher NH4 +-N contents in soil particularly in the ALF-treated soil where NH4 +-N contents were two times higher than in LF-treated soil during the 55-171-day interval. At the end of the incubation (171 days), 32.9 and 24.2 mg N kg-1 dry soil were mineralized in the ASF- and SF-treated soils, respectively, but no mineralization occurred in LF- and S-treated soils, although acidification decreased N immobilization in ALF- (-25.3 mg N kg-1 soil) and AS- (-12.7 mg N kg-1 soil) compared to LF- (-34.4 mg N kg-1 soil) and S-treated (-18.6 mg N kg-1 soil) soils, respectively. Most of the dissolved CO2 was lost during the acidification process. More than 90% of the applied C in the LF-treated soil was lost during the incubation, indicating a high availability of the added organic compounds. Nitrous oxide emissions occurred only after day 12 and at a lower rate in soils treated with acidified than nonacidified slurries. However, during the first 61 days of incubation, 1,157 μg N kg-1 soil was lost as N2O in the AS-treated soil and only 937 in the S-treated soil. © 2010 Springer-Verlag.

Fangueiro D.,University of Lisbon | Surgy S.,University of Lisbon | Fraga I.,CITAB | Cabral F.,University of Lisbon | Coutinho J.,C. Quimica
Agriculture, Ecosystems and Environment | Year: 2015

Animal slurry injection is considered the most effective solution to minimize ammonia (NH3) emissions at the field scale, but band application of slurry treated by acidification and/or solid-liquid separation may be a good alternative. The main objective of our study was to compare the overall efficiency of band application of acidified cattle slurry (Band-ARS), the liquid fraction (Band-LF), or acidified LF (Band-ALF) relative to raw cattle slurry injection (RSI). Two control treatments were also considered: the traditional broadcast application of raw slurry, immediately followed by soil incorporation (Broad-RS), and an unfertilized plot (CTR). A field experiment was performed to follow NH3, nitrous oxide (N2O), and methane (CH4) emissions, quantify plant yields and slurry nutrients use efficiency, and assess the impact on soil quality with special emphasis on enzymatic activity. Our results show that Band-ARS led to NH3, N2O and CH4 emissions similar to RSI while higher NH3 emissions were observed in the Band-LF treatment relative to RSI. A decrease in crop yields was detected for the Band-ALF treatment, relative to RSI, but no significant (P>0.05) differences were found between the other treatments considered. Application to soil of acidified materials had no negative impact on enzymatic activity or soil characteristics, when compared to CTR. Overall, band application of acidified slurry appears as a good alternative to slurry injection. © 2015.

Morel S.,University of Bordeaux 1 | Lespine C.,University of Bordeaux 1 | Coureau J.-L.,University of Bordeaux 1 | Planas J.,Technical University of Madrid | Dourado N.,CITAB
International Journal of Solids and Structures | Year: 2010

For composites and adhesive joints, the determination of the cohesive zone parameters from Double Cantilever Beam specimens loaded with pure moments is now well established and documented. However, for quasibrittle materials used in Civil Engineering such as concrete or wood, the difficulty to apply a pure bending moment lies inappropriated the method used for composites. Nevertheless, the one-to-one correspondence which exists between the R-curve and the softening curve is here revisited and adapted for any kind of specimen geometry and for the bilinear approximation of the softening function, well-known to successfully describe the failure of a wide group of quasibrittle materials. It is shown that even though the connections between the cohesive parameters and the 'equivalent LEFM' R-curve are geometry and material dependent, their trends are preserved whatever the specimen geometry and the material are. The outline of a general estimation procedure of the cohesive zone parameters funded on the equivalent LEFM R-curve is proposed. © 2009 Elsevier Ltd. All rights reserved.

Campilho R.D.S.G.,University of Porto | de Moura M.F.S.F.,University of Porto | Ramantani D.A.,University of Porto | Morais J.J.L.,CITAB | Domingues J.J.M.S.,Polytechnic Institute of Porto
Composites Science and Technology | Year: 2010

This work reports on an experimental and finite element method (FEM) parametric study of adhesively-bonded single and double-strap repairs on carbon-epoxy structures under buckling unrestrained compression. The influence of the overlap length and patch thickness was evaluated. This loading gains a particular significance from the additional characteristic mechanisms of structures under compression, such as fibres microbuckling, for buckling restrained structures, or global buckling of the assembly, if no transverse restriction exists. The FEM analysis is based on the use of cohesive elements including mixed-mode criteria to simulate a cohesive fracture of the adhesive layer. Trapezoidal laws in pure modes I and II were used to account for the ductility of most structural adhesives. These laws were estimated for the adhesive used from double cantilever beam (DCB) and end-notched flexure (ENF) tests, respectively, using an inverse technique. The pure mode III cohesive law was equalled to the pure mode II one. Compression failure in the laminates was predicted using a stress-based criterion. The accurate FEM predictions open a good prospect for the reduction of the extensive experimentation in the design of carbon-epoxy repairs. Design principles were also established for these repairs under buckling. © 2009 Elsevier Ltd. All rights reserved.

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