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Nomenclatura Unesco > (33) Ciencias Tecnológicas

Mostrando recursos 341 - 360 de 2,145

341. Classical and Optimal Active Vibration Control of Smart Piezoelectric Beams - C.M.A. Vasques; J.D. Rodrigues

342. A Layerwise Model for Soft Core Sandwich Panels - R. Moreira; J.D. Rodrigues

343. Finite Element Modelling of Beams with Arbitrary Active Constrained Layer Damping Treatments - C.M.A. Vasques; B. Mace; P. Gardonio; J.D. Rodrigues

344. Educação em ciências: preparando cidadãos para a realidade científica e tecnológica do novo milênio - Rosito, João B A

345. Educação em ciências: preparando cidadãos para a realidade científica e tecnológica do novo milênio - Miwa, Clívia Pazin

346. Successive loadings of reactant in the hydrogen generation by hydrolysis of sodium borohydride in batch reactors - M. J. F. Ferreira; V. R. Fernandes; C. M. Rangel; L. Gales; A. M. F. R. Pinto
In this paper, for the first time, an experimental investigation is presented of five successive loadings of reactant alkaline solution of sodium borohydride (NaBH4) for hydrogen generation, using an improved nickel-based powder catalyst, under uncontrolled ambient conditions. The experiments were performed in two batch reactors with internal volumes of 0.646 l and of 0.369 l. The compressed hydrogen generated, at pressures below hydrogen critical pressure, gives emphasis on the importance of considering solubility effects during reaction, leading to storage of hydrogen in the liquid phase inside the reactor. The present work suggests that the sodium metaborate by-product formed by the...

347. Durability and reutilization capabilities of a Ni-Ru catalyst for the hydrolysis of sodium borohydride in batch reactors - A.M.F.R.Pinto; M.J.F. Ferreira; V.R. Fernandes; C. M. Rangel
The study of catalyst durability and reutilization on catalyzed hydrolysis of sodium borohydride is essential from an application point of view. Few works on this topic are available in the literature. In the present work, a powder nickel-ruthenium based catalyst, unsupported, used in two different schemes of NaBH 4 hydrolysis (alkaline and alkali free hydrolysis), performed in batch reactors with different volumes and bottom geometries (flat and conical), was investigated in terms of durability and reutilization capabilities, throughout 300 cycles. For the alkaline NaBH 4 hydrolysis, the H 2 generation rate progressively decreases with catalyst reused and only ∼25% of...

348. Influence of wearing an unstable shoe construction on compensatory control of posture - Andreia S.P. Sousa; Rui Macedo; Rubim Santos; João Manuel R. S. Tavares
This study investigated the influence of wearing unstable shoe construction (WUS) on compensatory postural adjustments (CPA) associated with external perturbations. Thirty two subjects stood on a force platform resisting an anterior-posterior horizontal force applied to a pelvic belt via a cable, which was suddenly released, under two conditions: barefoot and WUS. The electromyographic (EMG) activity of gastrocnemius medialis, tibialis anterior, rectus femoris, biceps femoris, rectus abdominis, and erector spinae muscles and the centre of pressure (CoP) displacement were acquired to study CPA. The EMG signal was used to assess individual muscle activity and latency, antagonist co-activation and reciprocal activation at...

349. Development of a Cost-Effective End-Use Application for Thermoset Composite Wastes as Reinforcement for Polymer Concrete Materials - Maria Cristina Ribeiro; Ana Castro; Meixedo JPM; António Fiúza

350. Sustainable waste recycling solution for the glass fibre reinforced polymer composite materials industry - Ana Castro; Maria Cristina Ribeiro; João Silva; António Fiúza; Maria De Lurdes Dinis

351. Development of a Cost-Effective End-Use Application for Thermoset Composite Wastes as Reinforcement for Polymer Concrete Materials’ - Maria Cristina Ribeiro; Ana Castro

352. Integrated recycling approach for GFRP pultrusion wastes: Recycling and Reuse Assessment into New Composite Materials using Fuzzy Boolean Nets - Ana Castro; Maria Cristina Ribeiro; João Silva; António Fiúza; Maria De Lurdes Dinis

353. Case Study on the Eco-Efficiency Performance of a Composite Processing Industry: Evaluation and Quantification of Potential Improvements - Maria Cristina Ribeiro; Ana Castro; João Silva; António Fiúza; Maria De Lurdes Dinis

354. Optimizing the energy consumption on pultrusion process - Maria Cristina Ribeiro; Ana Castro; Maria De Lurdes Dinis; António Fiúza

355. Development of a Cost-Effective End-Use Application for Thermoset Composite Wastes as Reinforcement for Polymer Concrete Materials’ - Maria Cristina Ribeiro; Ana Castro

356. Objects Matching using Optimization Techniques - Luísa F. Bastos; João Manuel R. S. Tavares
Neste trabalho, o problema do emparelhamento de objectos (compostos por dados pontuais) é tratado como um problema de optimização global. Esta nova técnica é comparada com uma de índole local, previamente existente, o que permite verificar que os resultados melhoram significativamente. São também apresentadas duas metodologias, previamente desenvolvidas, que permitem a quantificação das afinidades entre os dados pontuais dos objectos. Uma dessas metodologias é baseada na análise modal da forma, enquanto a segunda utiliza o método dos elementos finitos e a análise modal. Habitualmente, as soluções de emparelhamento utilizadas permitem apenas correspondências do tipo "um com um". No entanto, existem...

357. A Prototype for the Acquisition and Analysis of the 3D Mandibular Movement - Isa C. T. Santos; João Manuel R. S. Tavares; Joaquim Mendes; Manuel P. F. Paulo
In Dental Medicine is essential to know the mandibular cinematic to simulate the temporomandibular joints, to position teeth moulds in articulators, and to reproduce the mandibular movements in order to insure a satisfactory occlusion. Currently, both commercial and custom made devices are considered expensive and difficult to use in common clinical situations. Considering these disadvantages, it was developed a new system for the acquisition, visualization and analysis of the 3D mandibular movement that is economical, easy to use and sufficiently precise, [1, 2].

358. External Anatomical Shapes Reconstruction from Turntable Image Sequences using a Single off-the-shelf Camera - Teresa C. S. Azevedo; João Manuel R. S. Tavares; Mário A. P. Vaz
Three-dimensional (3D) human body reconstruction and modeling from two-dimensional (2D) images is a topic of great interest and research but still remains a difficult problem to solve. Volumetric based methods are commonly used to solve this type of problem. With those methods, from a turntable image sequence of an object, a 3D model can be built. The final goal of the work presented in this paper is to reconstruct all-round 3D models of external anatomical shapes with good accuracy and photorealistic appearance, using a single off-the-shelf camera and a volumetric method.

359. Acquisition and Analysis of the 3D Mandibular Movement using a Device based on Electromagnetic Sensors and a Neural Network - Isa C. T. Santos; João Manuel R. S. Tavares; Joaquim Gabriel Mendes; Manuel P. F. Paulo
In Dental Medicine, the study of the mandibular movement has an important role in oral rehabilitation as it allows the diagnosis of pathologies in the temporomandibular joint and the definition of adequate treatment plans. In this paper, a new device specially developed for the acquisition and analysis of the 3D mandibular movement is presented. As its main support structure is adopted a facial arc and electromagnetic sensors are employed to acquire the mandibular movement. To transform into 3D cartesian coordinates the electrical signals outputted by the sensors used a neural network is employed. A custom made computational application was developed...

360. Control a 2-Axis Servomechanism by Gesture Recognition using a Generic WebCam - João Manuel R. S. Tavares; Ricardo Ferreira; Francisco Freitas
This paper presents two approaches used to control a 2-axis servomechanism by gesture recognition. For both approaches, the adopted control philosophy was: In the system’s learning phase, the control images are acquired by a generic webcam and associated to the desired orders. On the other hand, in the working phase, each control image is acquired, by the same webcam and, by comparison with the stored orders images, the desired order is recognized and processed by the servomechanism in quasi real time. In this paper, the used servomechanism and both implemented approaches are described, and are indicated some advantages and weakness...

 

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