Export 174 results:
Sort by: Author Title Type [ Year  (Desc)]
2011
Valtchev, {Stanimir Stoyanov}, and DEE Group Author. "An UHF Wireless Power Harvesting System - Analysis and Design." PES 2011: Proceedings of extended abstracts. 2011. 141-142. Abstract

This paper presents a system to harvest electromagnetic energy from the environment. The proposed solution differs from others already existent in the literature because it makes possible to harvest energy from a large frequency spectrum. Typically the existing energy harvesting systems only gather energy from one specific source, thus not taking advantage of the several RF sources existing in one place. The full system and its componentsare simulated and implemented, and the results obtained are shown. The system harvest energy from UHF sources, and converts the harvested energy to a DC voltage, in order to feed electronic devices. This conversion is made through the utilization of a voltage multiplier, followed by a voltage regulator.

Lourenço, João M. "Understanding Transactional Memory (Extended Abstract)." Hardware and Software: Verification and Testing. Eds. Sharon Barner, Ian Harris, Daniel Kroening, and Orna Raz. Vol. 6504. Lecture Notes in Computer Science, 6504. Springer Berlin / Heidelberg, 2011. 1-2. Abstracthvc2010-understanding_transactional_memory.pdf

Transactional Memory [3] (TM) is a new paradigm for concurrency control that brings the concept of transactions, widely known from the Databases community, into the management of data located in main memory. TM delivers a powerful semantics for constraining concurrency and provides the means for the extensive use of the available parallel hardware. TM uses abstractions that promise to ease the development of scalable parallel applications by achieving performances close to fine-grained locking while maintaining the simplicity of coarse-grained locking.

Amado, M. P., and M. R. Ribeiro Urban Sprawl promoted through Master Planning. World Congress of Sustainable Building. Helsinki, Finland: SB11, 2011.
R. Ramos, J. Castro, J. Araújo, and F. Alencar. "A Use Case Package Refactoring: Dealing with the Large, Scattering or Tangling Use Case Model Problems." VIII Latin American Conference on Pattern Languages of Programming - SugarLoafPlop. Springer-Verlag, 2011. Abstract

n/a

Valtchev, Stanimir. "An UHF Wireless Power Harvesting System – Analysis and Design." International Journal of Emerging Sciences (IJES) (2011). Abstract
n/a
Valtchev, Stanimir. "An UHF Wireless Power Harvesting System – Analysis and Design." 10th International Conference on Applied Electromagnetics (\cyrchar\CYRP\cyrchar\CYRE\cyrchar\CYRS Conference). 2011. Abstract
n/a
"An UHF Wireless Power Harvesting System – Analysis and Design." International Journal of Emerging Sciences (IJES) (2011). Abstract
n/a
Guimarães, D., J. P. Santos, M. L. Carvalho, G. Vale, H. M. Santos, V. Geraldes, I. Rocha, and J. L. Capelo. "Ultrasonic energy as a tool to overcome some drawbacks in the determination of lead in brain tissue and urine of rats." Talanta. 86 (2011): 442-446 . AbstractWebsite

An ultrasonic assisted solid‚Äìliquid extraction method was developed to determine the level of lead in the brain and urine of rats. Lead was determined by electrothermal atomic absorption spectrometry with longitudinal-Zeeman background correction. Several analytical drawbacks were addressed and overcome, namely small brain sample mass and the formation of precipitate in the urine samples. Utrasonication provided by an ultrasonic probe succeeded in extracting lead from brain samples. Furthermore, it was demonstrated that the formation of a precipitate lowered the lead content in the liquid phase of the urine. Lead was back extracted from the precipitate to the liquid phase with the aid of ultrasonic energy and acidifying the urine with 10% v/v nitric acid. A microwave-assisted acid digestion protocol was used to check the completeness of the lead extraction. The within bath and between bath precision was 5% (n = 9) and 7% (n = 3) respectively. The limit of quantification was 1.05 Œºg g‚àí1 for brain samples and 2.1 Œºg L‚àí1 for urine samples. A total of 6 samples of urine and 12 samples of brain from control rats and another 6 samples of urine and 12 samples of brain from rats fed with tap water rich in lead acetate were used in this research. Lead levels in brain and urine from exposed rats ranged from1.9 ¬± 0.2 Œºg g‚àí1 to 3.5 ¬± 0.2 Œºg g‚àí1 and from 752 ¬± 56 Œºg L‚àí1 to 60.9 ¬± 1.2 mg L‚àí1 respectively. Statistically significant differences of levels of lead in brain and urine were found between exposed and non exposed rats.

Guimarães, D., J. P. Santos, M. L. Carvalho, G. Vale, H. M. Santos, V. Geraldes, I. Rocha, and J. L. Capelo. "Ultrasonic energy as a tool to overcome some drawbacks in the determination of lead in brain tissue and urine of rats." Talanta. 86 (2011): 442-446. AbstractWebsite

An ultrasonic assisted solid‚Äìliquid extraction method was developed to determine the level of lead in the brain and urine of rats. Lead was determined by electrothermal atomic absorption spectrometry with longitudinal-Zeeman background correction. Several analytical drawbacks were addressed and overcome, namely small brain sample mass and the formation of precipitate in the urine samples. Utrasonication provided by an ultrasonic probe succeeded in extracting lead from brain samples. Furthermore, it was demonstrated that the formation of a precipitate lowered the lead content in the liquid phase of the urine. Lead was back extracted from the precipitate to the liquid phase with the aid of ultrasonic energy and acidifying the urine with 10% v/v nitric acid. A microwave-assisted acid digestion protocol was used to check the completeness of the lead extraction. The within bath and between bath precision was 5% (n = 9) and 7% (n = 3) respectively. The limit of quantification was 1.05 Œºg g‚àí1 for brain samples and 2.1 Œºg L‚àí1 for urine samples. A total of 6 samples of urine and 12 samples of brain from control rats and another 6 samples of urine and 12 samples of brain from rats fed with tap water rich in lead acetate were used in this research. Lead levels in brain and urine from exposed rats ranged from1.9 ¬± 0.2 Œºg g‚àí1 to 3.5 ¬± 0.2 Œºg g‚àí1 and from 752 ¬± 56 Œºg L‚àí1 to 60.9 ¬± 1.2 mg L‚àí1 respectively. Statistically significant differences of levels of lead in brain and urine were found between exposed and non exposed rats.

Carreira, R. J., M. S. Diniz, and J. L. Capelo. "Ultrasonic-based protein quantitation by18O-labeling: Optimization and comparison between different procedures." Rapid Communications in Mass Spectrometry. 25 (2011): 75-87. AbstractWebsite
n/a
Louren{\c c}o, João. "Understanding Transactional Memory (Extended Abstract)." Hardware and Software: Verification and Testing. Eds. Sharon Barner, Ian Harris, Daniel Kroening, and Orna Raz. Vol. 6504. Lecture Notes in Computer Science, 6504. Springer Berlin / Heidelberg, 2011. 1-2. Abstract
Transactional Memory [3] (TM) is a new paradigm for concurrency control that brings the concept of transactions, widely known from the Databases community, into the management of data located in main memory. TM delivers a powerful semantics for constraining concurrency and provides the means for the extensive use of the available parallel hardware. TM uses abstractions that promise to ease the development of scalable parallel applications by achieving performances close to fine-grained locking while maintaining the simplicity of coarse-grained locking.
Coito, F., and L. B. Palma. "Unfalsification based Fault Tolerant Controller." Emerging Technologies & Factory Automation (ETFA), 2011 IEEE 16th Conference on. IEEE, 2011. 1-4. Abstract
n/a
Neagu, E. R., C. J. Dias, M. C. Lanca, R. Igreja, P. Inacio, and J. N. Marat-Mendes. "The use of the final thermally stimulated discharge current technique to study the molecular movements around glass transition." Journal of Non-Crystalline Solids. 357 (2011): 385-390. Abstract
n/a
ER, Neagu, Dias CJ, Lança MC, Igreja R, Inacio P, and Marat-Mendes J. N. "The use of the final thermally stimulated discharge current technique to study the molecular movements around glass transition." 354.2 (2011). Abstract

During electric polarization charge is injected into the material. The structure is decorated with space charge and during the subsequent heating an apparent peak and the genuine peaks that are related to dipole randomization and charge detrapping are observed. The method is used here to analyze the molecular movements in polyimide in the temperature range from 293 to 623K. Two weak relaxations have been observed around 337K and around 402K. The electrical conductivity changes with temperature in agreement with the Arrhenius law only below (W=(0.84±0.03) eV ) and above ( W=(0.82±0.03) eV) the temperature range where the β relaxation is observed. The variation of the electrical conductivity with temperature, in the range of the β relaxation, is controlled by the variation of the charge currier mobility with temperature and it shows a non-Arrhenius behavior. We suggest that the β1 sub-glass relaxation is related to the rotation or oscillation of phenyl groups and the β2 sub-glass relaxation is related to the rotation or oscillation of the imidic ring. At higher temperatures an apparent peak was observed. The relaxation time of the trapped charge, at 573K, is high than 8895s.

Neagu, E. R., C. J. Dias, M. C. Lanca, R. Igreja, P. Inacio, and J. N. Marat-Mendes. "The use of the final thermally stimulated discharge current technique to study the molecular movements around glass transition." Journal of Non-Crystalline Solids. 357 (2011): 385-390. AbstractWebsite

During electric polarization charge is injected into the material. The structure is decorated with space charge and during the subsequent heating an apparent peak and the genuine peaks that are related to dipole randomization and charge detrapping are observed. The method is used here to analyze the molecular movements in polyimide in the temperature range from 293 to 623 K. Two weak relaxations have been observed around 337 K and around 402 K. The electrical conductivity changes with temperature in agreement with the Arrhenius law only below (W= (0.84 +/- 0.03) eV) and above ( W (0.82 +/- 0.03) eV) the temperature range where the beta relaxation is observed. The variation of the electrical conductivity with temperature, in the range of the beta relaxation, is controlled by the variation of the charge currier mobility with temperature and it shows a non-Arrhenius behavior. We suggest that the beta(1) sub-glass relaxation is related to the rotation or oscillation of phenyl groups and the beta(2) sub-glass relaxation is related to the rotation or oscillation of the imidic ring. At higher temperatures an apparent peak was observed. The relaxation time of the trapped charge, at 573 K, is high than 8895 s. (C) 2010 Elsevier B.V. All rights reserved.

Neagu, E. R., C. J. Dias, M. C. Lanca, R. Igreja, P. Inacio, and J. N. Marat-Mendes. "The use of the final thermally stimulated discharge current technique to study the molecular movements around glass transition." Journal of Non-Crystalline Solids. 357 (2011): 385-390. Abstract
n/a
2010
Ribeiro, Celso, Pedro Brogueira, Guilherme Lavareda, Carlos N. Carvalho, Ana Amaral, Luis Santos, Jorge Morgado, Ulrich Scherf, and Vasco D. B. Bonifacio. "Ultrasensitive microchip sensor based on boron-containing polyfluorene nanofilms." BIOSENSORS & BIOELECTRONICS. 26 (2010): 1662-1665. Abstract

A fluorene-based pi-conjugated copolymer with on-chain dibenzoborole units was used in the development of a nanocoated gold interdigitated microelectrode array device which successfully detects fluoride in a broad range of concentrations (10(-11)-10(-4) M) in aqueous solution, upon impedance spectroscopy measurements. A calibration curve obtained over this range of concentrations and a new analytical method based on impedance spectroscopy measurements in aqueous solution is proposed. The sensor nanofilm was produced by spin-coating and diagnosed via spectroscopic ellipsometry, AFM, and electrically conductivity techniques. Changes in the conductivity due to the boron-fluoride complex formation seem to be the major mechanism behind the dependence of impedimetric results on the fluoride concentration. (C) 2010 Elsevier B.V. All rights reserved.

Ribeiro, Celso, Pedro Brogueira, Guilherme Lavareda, Carlos Nunes de Carvalho, Ana Amaral, Luis Santos, Jorge Morgado, Ulrich Scherf, and Vasco D. B. Bonifacio. "Ultrasensitive microchip sensor based on boron-containing polyfluorene nanofilms." BIOSENSORS & BIOELECTRONICS. 26 (2010): 1662-1665. Abstract

A fluorene-based pi-conjugated copolymer with on-chain dibenzoborole units was used in the development of a nanocoated gold interdigitated microelectrode array device which successfully detects fluoride in a broad range of concentrations (10(-11)-10(-4) M) in aqueous solution, upon impedance spectroscopy measurements. A calibration curve obtained over this range of concentrations and a new analytical method based on impedance spectroscopy measurements in aqueous solution is proposed. The sensor nanofilm was produced by spin-coating and diagnosed via spectroscopic ellipsometry, AFM, and electrically conductivity techniques. Changes in the conductivity due to the boron-fluoride complex formation seem to be the major mechanism behind the dependence of impedimetric results on the fluoride concentration. (C) 2010 Elsevier B.V. All rights reserved.

Parreira, P., G. Lavareda, J. Valente, F. T. Nunes, A. Amaral, and Nunes C. de Carvalho. "Undoped InOx Films Deposited by Radio Frequency Plasma Enhanced Reactive Thermal Evaporation at Room Temperature: Importance of Substrate." JOURNAL OF NANOSCIENCE AND NANOTECHNOLOGY. 10 (2010): 2701-2704. Abstract

Conductive and transparent undoped thin films of indium oxide (InOx), 120 nm average thick, were deposited by radio frequency plasma enhanced reactive thermal evaporation (rf-PERTE) of indium in the presence of oxygen at room temperature. Several substrates were used in order to study their influence on the main properties of these films: alkali free (AF) glass, fused silica, crystalline silicon and polyethylene terephthalate (PET). Surface morphology of the InOx films as a function of the substrates was observed by SEM and showed that the undoped InOx films obtained are nano-structured. For the c-Si substrate, InOx films with increased grain size are obtained, induced by the crystalline substrate. Films deposited on fused silica and AF glass substrates show a nano-grainy surface with similar surface morphologies. The InOx films deposited on AF glass show the highest values of both: electrical conductivity of about 1100 (Omega cm)(-1) and visible transmittance of 85%. The substrate has a greater influence on the surface morphology of the films when a polymer (PET) is used. InOx films deposited on PET show a decrease in the electrical conductivity (90 (Omega cm)(-1)) and a slight decrease in the average visible transmittance (78%).

Parreira, P., G. Lavareda, J. Valente, F. T. Nunes, A. Amaral, and C. Nunes de Carvalho. "Undoped InOx Films Deposited by Radio Frequency Plasma Enhanced Reactive Thermal Evaporation at Room Temperature: Importance of Substrate." JOURNAL OF NANOSCIENCE AND NANOTECHNOLOGY. 10 (2010): 2701-2704. Abstract

Conductive and transparent undoped thin films of indium oxide (InOx), 120 nm average thick, were deposited by radio frequency plasma enhanced reactive thermal evaporation (rf-PERTE) of indium in the presence of oxygen at room temperature. Several substrates were used in order to study their influence on the main properties of these films: alkali free (AF) glass, fused silica, crystalline silicon and polyethylene terephthalate (PET). Surface morphology of the InOx films as a function of the substrates was observed by SEM and showed that the undoped InOx films obtained are nano-structured. For the c-Si substrate, InOx films with increased grain size are obtained, induced by the crystalline substrate. Films deposited on fused silica and AF glass substrates show a nano-grainy surface with similar surface morphologies. The InOx films deposited on AF glass show the highest values of both: electrical conductivity of about 1100 (Omega cm)(-1) and visible transmittance of 85%. The substrate has a greater influence on the surface morphology of the films when a polymer (PET) is used. InOx films deposited on PET show a decrease in the electrical conductivity (90 (Omega cm)(-1)) and a slight decrease in the average visible transmittance (78%).

Santos, H. M., R. Carreira, M. S. Diniz, M. G. Rivas, C. Lodeiro, JJG Moura, and J. L. Capelo. "Ultrasonic multiprobe as a new tool to overcome the bottleneck of throughput in workflows for protein identification relaying on ultrasonic energy." Talanta. 81 (2010): 55-62. AbstractWebsite
n/a
Nunes, Isabel L., and Jurek Kirakowski Usabilidade de interfaces – versão Portuguesa do Software Usability Measurement Inventory (SUMI) [Interfaces Usability – Portuguese version of the Software Usability Measurement Inventory (SUMI)]. Eds. P. Arezes, J. S. Baptista, M. P. Barroso, P. Carneiro, P. Cordeiro, N. Costa, R. Melo, A. S. Miguel, and G. P. Perestrelo. Occupational Safety and Hygiene (SHO10). Guimarães - Portugal: SPOSHO, 2010. Abstract
n/a
Antunes, R., F. Coito, and H. Duarte-Ramos. "Using Human Dynamics to Improve Operator Performance." Emerging Trends in Technological Innovation (2010): 393-400. Abstract
n/a
2009
Lourenço, João M., Ricardo J. Dias, João Luís, Miguel Rebelo, and Vasco Pessanha. "Understanding the Behavior of Transactional Memory Applications." Proceedings of the 7th Workshop on Parallel and Distributed Systems: Testing, Analysis, and Debugging (PADTAD'09). {PADTAD}'09. New York, NY, USA: ACM, 2009. 31-39. Abstractpadtad2009.pdf

Transactional memory is a new trend in concurrency control that was boosted by the advent of multi-core processors and the near to come many-core processors. It promises the performance of finer grain with the simplicity of coarse grain threading. However, there is a clear absence of software development tools oriented to the transactional memory programming model, which is confirmed by the very small number of related scientific works published until now. This paper describes ongoing work. We propose a very low overhead monitoring framework, developed specifically for monitoring TM computations, that collects the transactional events into a single log file, sorted in a global order. This framework is then used by a visualization tool to display different types of charts from two categories: statistical charts and thread-time space diagrams. These last diagrams are interactive, allowing to identify conflicting transactions. We use the visualization tool to analyse the behavior of two different, but similar, testing applications, illustrating how it can be used to better understand the behavior of these transactional memory applications.