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2013
b b b b b Figueiredo, V.a b, Pinto Deuermeier Barros Alves Martins Fortunato J. V. a J. "P-Type CuxO thin-film transistors produced by thermal oxidation." IEEE/OSA Journal of Display Technology. 9 (2013): 735-740. AbstractWebsite

Thin-films of copper oxide Cu O were produced by thermal oxidation of metallic copper (Cu) at different temperatures (150-450 C). The films produced at temperatures of 200, 250 and 300 C showed high Hall motilities of 2.2, 1.9 and 1.6 cm V s , respectively. Single Cu O phases were obtained at 200 C and its conversion to CuO starts at 250 C. For lower thicknesses 40 nm, the films oxidized at 250 C showed a complete conversion to CuO phase. Successful thin-film transistors (TFTs) were produce by thermal oxidation of a 20 nm Cu film, obtaining p-type Cu O (at 200 C) and CuO (at 250 C) with On/Off ratios of 6 10 and 1 10 , respectively. © 2005-2012 IEEE.

Martins, R.a, Pereira Fortunato L. b E. c. "Paper electronics: A challenge for the future." Digest of Technical Papers - SID International Symposium. Vol. 44. 2013. 365-367. Abstract

In this paper we report results concerning the use of paper as substrate and as an electronic component for the next generation of sustainable low cost electronic systems, where different examples of applications are given. © 2013 Society for Information Display.

Parthiban, S., Elangovan Nayak Gonçalves Nunes Pereira Barquinha Busani Fortunato Martins E. P. K. "Performances of microcrystalline zinc tin oxide thin-film transistors processed by spray pyrolysis." IEEE/OSA Journal of Display Technology. 9 (2013): 825-831. AbstractWebsite

In this work, we report results concerning the performances of thin-film transistors (TFTs) where the channel layer is based on microcrystalline zinc tin oxide (ZTO) processed by spray pyrolysis technique. TFTs made with 30 nm thick ZTO channel layer deposited at a substrate temperature of 400 C and 300 Cexhibited, respectively, a saturation mobility of 2.9 cm V s and 1.45 cm V s ; voltage of 0.15 V, and 0.2 V; a sub-threshold swing of 400 mV/dec and 500 mV/dec; ON/OFF ratio at the onset of hard saturation current of 3.5 10 and 6 10 , for a drain to source voltage of 10 V (close to or below the gate to source voltage). This indicates that the substrate temperature is relevant in determining the devices' electronic performances. © 2013 IEEE.

Valtchev, Stanimir. "Perspectives of Tunnel FET (TFET) in the Ultra-Low-Power Analog-Circuit design." Proceedings 28th Conference DCIS. 2013. Abstract
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Branquinho, R., Pinto Busani Barquinha Pereira Baptista Martins Fortunato J. V. T. "Plastic compatible sputtered ta-inf o sensitive layer for oxide semiconductor tft sensors." IEEE/OSA Journal of Display Technology. 9 (2013): 723-728. AbstractWebsite

The effect of post-deposition annealing temperature on the pH sensitivity of room temperature RF sputtered +{\hbox{Ta}}-{2}{\hbox{O}}5 was investigated. Structural and morphological features of these films were analyzed before and after annealing at various temperatures. The deposited films are amorphous up to 600 +^{\circ}{\hbox{C}}+ and crystallize at 700 +^{\circ}{\hbox{C}}+ in an orthorhombic phase. Electrolyte-insulator- semiconductor (EIS) field effect based sensors with an amorphous +{\hbox{Ta}}-{2}{\hbox{O}}5 sensing layer showed pH sensitivity above 50 mV/pH. For sensors annealed above 200 +^{\circ}{\hbox{C}}+ pH sensitivity decreased with increasing temperature. Stabilized sensor response and maximum pH sensitivity was achieved after low temperature annealing at 200 +^{\circ}{\hbox{C}}+ , which is compatible with the use of polymeric substrates and application as sensitive layer in oxides TFT-based sensors. © 2005-2012 IEEE.

Ruivo, C.R.a b, Ferreira Vaz P. M. c D. "Prediction of thermal load temperature difference values for the external envelope of rooms with setback and setup thermostats." Applied Thermal Engineering. 51 (2013): 980-987. AbstractWebsite

The Cooling Load Temperature Difference (CLTD) values available in the literature for using the simplified CLTD method only apply to rooms under constant indoor air temperature. Due to this limitation, the present paper extends the application of this simplified approach to cooling and heating loads estimation of rooms with daily and weekend setback and setup thermostats, and introduces the term thermal load temperature difference (TLTD). To generate the values of TLTD, a transient heat transfer model, and the corresponding numerical tool, has been developed to predict the thermal behaviour of multilayered walls and flat roofs. The sol-air temperature concept is used. The internal thermal capacity of the room is assumed negligible. The TLTD evolutions have been generated for a wall and a roof, of high mass construction, with setback and setup thermostats in winter and summer scenarios. The periods in which the room is unoccupied have been taken in due account. The TLTD evolutions allowed the estimation of: the energy transferred at the inner surface and the maximum thermal load. Among the cases studied, the relative difference found in the energy transferred through the sunlit envelope, roof or wall under summer conditions, is about 20% when the temperature control strategy is changed from A to B. © 2012 Elsevier Ltd. All rights reserved.

b b b b Ramos, A.M.a b, Pereira Cidade Pereira Branquinho Pereira Martins Fortunato S. a M. T. "Preparation and characterization of cellulose nanocomposite hydrogels as functional electrolytes." Solid State Ionics. 242 (2013): 26-32. AbstractWebsite

In this work Laponite was combined with a modified abundant natural polymer, (caboxymethyl cellulose), acrylic sodium salt polymer and lithium perchlorate aiming to produce inexpensive and sustainable nanocomposite electrolytes for functional electrochemical devices. Optical, electrochemical, structural, morphological and rheological characterization was performed in order to evaluate their properties and potential advantages as electrolyte. It was verified that the addition of Laponite led to an ionic conductivity at room temperature (25 C) in the range of 6 to 9 × 10- 5 Scm - 1 this value being then determined by the composition of the nanocomposite. These electrolytes were applied to electrochromic devices using evaporated nickel oxide thin film as the electrochromic layer. The devices exhibited a significant transmittance modulation that exceeds 45 % at 600 nm. © 2013 Elsevier B.V.

Sava, B. A. a, M. a Elisa, L. b Boroica, and R. C. C. c Monteiro. "Preparation method and thermal properties of samarium and europium-doped alumino-phosphate glasses." Materials Science and Engineering B: Solid-State Materials for Advanced Technology. 178 (2013): 1429-1435. AbstractWebsite

The present work investigates alumino-phosphate glasses from Li 2O-BaO-Al2O3-La2O3-P 2O5 system containing Sm3+ and Eu3+ ions, prepared by two different ways: a wet raw materials mixing route followed by evaporation and melt-quenching, and by remelting of shards. The linear thermal expansion coefficient measured by dilatometry is identical for both rare-earth-doped phosphate glasses. Comparatively to undoped phosphate glass the linear thermal expansion coefficient increases with 2 × 10-7 K-1 when dopants are added. The characteristic temperatures very slowly decrease but can be considered constant with atomic weight, atomic number and f electrons number of the doping ions in the case of Tg (vitreous transition temperature) and Tsr (high annealing temperature) but slowly increase in the case of Tir (low annealing temperature-strain point) and very slowly increase, being practically constant in the case of TD (dilatometric softening temperature). Comparatively to undoped phosphate glass the characteristic temperatures of Sm and Eu-doped glasses present lower values. The higher values of electrical conductance for both doped glasses, comparatively to usual soda-lime-silicate glass, indicate a slightly reduced stability against water. The viscosity measurements, showed a quasi-linear variation with temperature the mean square deviation (R 2) being ranged between 0.872% and 0.996%. The viscosity of doped glasses comparatively to the undoped one is lower at the same temperature. Thermogravimetric analysis did not show notable mass change for any of doped samples. DSC curves for both rare-earth-doped phosphate glasses, as bulk and powdered samples, showed Tg values in the range 435-450 C. Bulk samples exhibited a very weak exothermic peak at about 685 C, while powdered samples showed two weak exothermic peaks at about 555 C and 685 C due to devitrification of the glasses. Using designed melting and annealing programs, the doped glasses were improved regarding bubbles and cords content and strain elimination. © 2013 Elsevier B.V. All rights reserved.

Maneira, António, and João Correia de Freitas. "Projetos de v{\'ıdeos interativos no ensino superior: multimédia semântico e a aprendizagem." III Colóquio Luso-Brasileiro de Educação a Distância e Elearning. http://lead.uab.pt/OCS/index.php/CLB/club/paper/view/173, 2013. Abstract
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2012
Amaro, P., F. Fratini, S. Fritzsche, P. Indelicato, J. P. Santos, and A. Surzhykov. "Parametrization of the angular correlation and degree of linear polarization in two-photon decays of hydrogenlike ions." Phys. Rev. A. 86 (2012): 042509. AbstractWebsite

The spontaneous two-photon emission in hydrogenlike ions is investigated within the framework of second- order perturbation theory and Dirac’s equation. Special attention is paid to the angular correlation of the emitted photons as well as to the degree of linear polarization of one of the two photons, if the second is just observed under arbitrary angles. Expressions for the angular correlation and the degree of linear polarization are expanded in powers of cosine functions of the two-photon opening angle, whose coefficients depend on the atomic number and the energy sharing of the emitted photons. The effects of including higher (electric and magnetic) multipoles upon the emitted photon pairs beyond the electric-dipole approximation are also discussed. Calculations of the coefficients are performed for the transitions 2s1/2 → 1s1/2, 3d3/2 → 1s1/2, and 3d5/2 → 1s1/2, along the entire hydrogen isoelectronic sequence (1

Amaro, P., F. Fratini, S. Fritzsche, P. Indelicato, J. P. Santos, and A. Surzhykov. "Parametrization of the angular correlation and degree of linear polarization in two-photon decays of hydrogenlike ions." Physical Review A. 86 (2012): 042509. AbstractWebsite

The spontaneous two-photon emission in hydrogenlike ions is investigated within the framework of second- order perturbation theory and Dirac’s equation. Special attention is paid to the angular correlation of the emitted photons as well as to the degree of linear polarization of one of the two photons, if the second is just observed under arbitrary angles. Expressions for the angular correlation and the degree of linear polarization are expanded in powers of cosine functions of the two-photon opening angle, whose coefficients depend on the atomic number and the energy sharing of the emitted photons. The effects of including higher (electric and magnetic) multipoles upon the emitted photon pairs beyond the electric-dipole approximation are also discussed. Calculations of the coefficients are performed for the transitions 2s1/2 → 1s1/2, 3d3/2 → 1s1/2, and 3d5/2 → 1s1/2, along the entire hydrogen isoelectronic sequence (1 Z 100).

Dias, Ricardo J., Vasco Pessanha, and João M. Lourenço. "Precise Detection of Atomicity Violations." Haifa Verification Conference. Lecture Notes in Computer Science. Haifa, Israel: Springer Berlin / Heidelberg, 2012. Abstracthvc2012.pdf

Concurrent programs that are free of unsynchronized ac- cesses to shared data may still exhibit unpredictable concurrency errors called atomicity violations, which include both high-level dataraces and stale-value errors. Atomicity violations occur when programmers make wrong assumptions about the atomicity scope of a code block, incorrectly splitting it in two or more atomic blocks and allow them to be interleaved with other atomic blocks. In this paper we propose a novel static analysis algorithm that works on a dependency graph of program variables and detects both high-level dataraces and stale-value errors. The algorithm was implemented for a Java Bytecode analyzer and its effectiveness was evaluated with some well known faulty programs. The results obtained show that our algorithm performs better than previous approaches, achieving higher precision for small and medium sized programs, making it a good basis for a practical tool.

Duarte, Faria, Inácio Micael, Lúcio Válter, and Ramos António. "Punching of Strengthened Concrete Flat Slabs—Experimental Analysis and Comparison with Codes." Structural Engineering International. 22 (2012): 202-214. AbstractWebsite

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Faria, Duarte M. V., Válter J. G. Lúcio, and A. Pinho Ramos. "Post-punching behaviour of flat slabs strengthened with a new technique using post-tensioning." Engineering Structures. 40 (2012): 383-397. AbstractWebsite

This work presents an experimental study concerning the post-punching behaviour of flat slabs strengthened with a new technique based on post-tensioning with anchorages by bonding using an epoxy adhesive. This strengthening technique proved efficient with respect to ultimate and serviceability states. Five slab specimens were tested in the post-punching range and it was found that the post-punching resistance was on average 78{%} of the punching resistance. This paper reports the development of strand forces and slab displacements from the beginning of the tests, including the bond stresses developed at several stages of the loading process. It was observed that top reinforcement bars were capable of transmitting post-punching loads to the prestressing strands. Taking this into account and based on the load bath envisaged from the column to the slab, expressions for the vertical load capacities corresponding to the parts of the load path are presented and compared with the experimental results, showing their ability to predict both ultimate loads and modes of failure. Compared with other strengthening techniques, the one proposed here not only upgrades ultimate and serviceability behaviour but also adds post-punching resistance, which is a great advantage in the event of progressive collapse, since it may avoid the collapse of an entire structure, thus reducing the risk of material and human losses.

M.I., Gomes, Caeiro F., and Henriques-Rodrigues L. PORT-PPWM extreme value index estimation. Proceedings of COMPSTAT 2012., 2012. Abstract2012_compstat2012.pdf

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GSL, Gaspar, Silva SJC, and Borges BJP Production and characterization of chitosan/calcium phosphate composite microspheres for bone tissue engineering therapeutics. Vol. 6. JOURNAL OF TISSUE ENGINEERING AND REGENERATIVE MEDICINE, 6., 2012. Abstract
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João, Gandra, Miranda Rosa M., Vilaça Pedro, and Velhinho Alexandre. "Production of functionally graded surface composites by friction surfacing." Mechanics of Nano, Micro and Macro Composite Structures. 2012. 1-2. Abstract
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Lavareda, G., C. Nunes de Carvalho, A. M. Ferraria, A. M. Botelho Do Rego, and A. Amaral. "p-Type Cuo(X) Thin Films by rf-Plasma Enhanced Reactive Thermal Evaporation: Influence of rf-Power Density." JOURNAL OF NANOSCIENCE AND NANOTECHNOLOGY. 12 (2012): 6754-6757. Abstract

Copper oxide is a well known p-type semiconductor material, usually obtained by thermal oxidation of copper thin-films within few minutes, at atmospheric pressure. In this paper, thin films of copper oxide that were deposited by radio-frequency plasma enhanced reactive thermal evaporation of copper at room temperature, without any post-deposition annealing treatment, are studied. The deposition of good quality p-type semiconductor oxide to be used in the fabrication of p-TFTs is the purpose of this work. The thickness of the films varies from 97 up to 160 nm. The influence of rf power density on chemical, electrical and optical properties of the films was studied. Samples present conductivity within the range of 6 x 10(-5) to 4 x 10(2) Omega(-1) cm(-1) (thermal activation energy in the interval 0.46 to 0.01 eV). The p-type conductivity of the films was confirmed by Seebeck effect in the more conductive samples. Surface composition obtained by XPS analysis was correlated with optical and electrical properties, showing that rf-power plays a main role in changes of material characteristics.

Lavareda, G., C. Nunes de Carvalho, A. M. Ferraria, A. M. Botelho Do Rego, and A. Amaral. "p-Type Cuo(X) Thin Films by rf-Plasma Enhanced Reactive Thermal Evaporation: Influence of rf-Power Density." JOURNAL OF NANOSCIENCE AND NANOTECHNOLOGY. 12 (2012): 6754-6757. Abstract

Copper oxide is a well known p-type semiconductor material, usually obtained by thermal oxidation of copper thin-films within few minutes, at atmospheric pressure. In this paper, thin films of copper oxide that were deposited by radio-frequency plasma enhanced reactive thermal evaporation of copper at room temperature, without any post-deposition annealing treatment, are studied. The deposition of good quality p-type semiconductor oxide to be used in the fabrication of p-TFTs is the purpose of this work. The thickness of the films varies from 97 up to 160 nm. The influence of rf power density on chemical, electrical and optical properties of the films was studied. Samples present conductivity within the range of 6 x 10(-5) to 4 x 10(2) Omega(-1) cm(-1) (thermal activation energy in the interval 0.46 to 0.01 eV). The p-type conductivity of the films was confirmed by Seebeck effect in the more conductive samples. Surface composition obtained by XPS analysis was correlated with optical and electrical properties, showing that rf-power plays a main role in changes of material characteristics.

Lopes, T. C., and M. P. Amado. "Prefabricação Aplicada ao Contexto da Reabilitação de Edifícios." 2ª Conferência de Reabilitação Sustentável de Edifícios no Espaço Lusófono. Caparica: FCT UNL - MAMAOT CV, 2012.
Myers, Timothy S., Neil J. Tabor, Louis L. Jacobs, and Octávio Mateus. "Palaeoclimate of the Late Jurassic of Portugal: Comparison with the Western United States." Sedimentology. 59.6 (2012): 1695-1717. Abstractmyers_et_al_2012_palaeoclimate_of_the_late_jurassic_of_portugal_comparison_with_the_western.pdfWebsite

Investigation of the palaeoclimatic conditions associated with Upper Jurassic strata in Portugal and comparison with published palaeoclimate reconstructions of the Upper Jurassic Morrison Formation in western North America provide important insights into the conditions that allowed two of the richest terrestrial faunas of this period to flourish. Geochemical analyses and observations of palaeosol morphology in the informally named Upper Jurassic Lourinhã formation of western Portugal indicate warm and wet palaeoclimatic conditions with strongly seasonal precipitation patterns. Palaeosol profiles are dominated by carbonate accumulations and abundant shrink-swell (vertic) features that are both indicative of seasonal variation in moisture availability. The δ18OSMOW and δDSMOW values of phyllosilicates sampled from palaeosol profiles range from +22·4‰ to +22·7‰ and −53·0‰ to −37·3‰, respectively. These isotope values correspond to temperatures of formation between 32°C and 39°C ± 3°, with an average of 36°C, which suggest surface temperatures between 27°C and 34°C (average 31°C). On average, these surface temperature estimates are 1°C higher than the highest summer temperatures modelled for Late Jurassic Iberia using general circulation models. Elemental analysis of matrix material from palaeosol B-horizons provides proxy (chemical index of alteration minus potassium) estimates of mean annual precipitation ranging from 766 to 1394 mm/year, with an average of approximately 1100 mm/year. Palaeoclimatic conditions during deposition of the Lourinhã formation are broadly similar to those inferred for the Morrison Formation, except somewhat wetter. Seasonal variation in moisture availability does not seem to have negatively impacted the ability of these environments to support rich and relatively abundant faunas. The similar climate between these two Late Jurassic terrestrial ecosystems is probably one of the factors which explains the similarity of their vertebrate faunas.

Barišić, Ankica, Pedro Monteiro, Vasco Amaral, Miguel Goulão, and Miguel Pessoa Monteiro. "Patterns for Evaluating Usability of Domain-Specific Languages." Proceedings of the Pattern Languages of Programs Conference, PLoP 2012. ACM, 2012. Abstract

For years the development of software artifacts was the sole domain of developers and project
managers. However, experience has taught us that the Users play a very important role in
software development and construction. On Domain Specific Languages the inclusion of the
domain experts directly in the development cycle is a very important characteristic, as they have
often an important role in making and constraining the domain of the language.
DSLs are credited with increased productivity and ease of use, but this fact is hardly ever proven.
Moreover, usability tests are frequently only performed at the final stages of the project when
changes have a significant impact on the budget. To help prevent this, in this paper we present a
pattern language for evaluating the usability of DSLs. Our patterns can help show how to use an
iterative usability validation development strategy to produce DSLs that can achieve a high
degree of usability.