Classification of lactose and mandelic acid THz spectra using subspace and wavelet-packet algorithms

This work compares classification results of lactose, mandelic acid and dl-mandelic acid, obtained on the basis of their respective THz transients. The performance of three different pre-processing algorithms applied to the time-domain signatures obtained using a THz-transient spectrometer are contrasted by evaluating the classifier performance. A range of amplitudes of zero-mean white Gaussian noise are used to artificially degrade the signal-to-noise ratio of the time-domain signatures to generate the data sets that are presented to the classifier for both learning and validation purposes. This gradual degradation of interferograms by increasing the noise level is equivalent to performing measurements assuming a reduced integration time. Three signal processing algorithms were adopted for the evaluation of the complex insertion loss function of the samples under study; a) standard evaluation by ratioing the sample with the background spectra, b) a subspace identification algorithm and c) a novel wavelet-packet identification procedure. Within class and between class dispersion metrics are adopted for the three data sets. A discrimination metric evaluates how well the three classes can be distinguished within the frequency range 0. 1 - 1.0 THz using the above algorithms.

Structural and optical properties on thulium-doped LHPG-grown Ta(2)O(5) fibres

Structural, spectroscopic and dielectric properties of thulium-doped laser-heated pedestal Ta(2)O(5) as-grown fibres were studied. Undoped samples grow preferentially with a single crystalline monoclinic structure. The fibre with the lowest thulium content (0.1 at%) also shows predominantly a monoclinic phase and no intra-4f(12) Tm(3+) recombination was observed. For sample with the highest thulium amount (1.0 at%), the appearance of a dominant triclinic phase as well as intraionic optical activation was observed. The dependence of photoluminescence on excitation energy allows identification of different site locations of Tm(3+) ions in the lattice. The absence of recombination between the first and the ground-state multiplets as well as the temperature dependence of the observed transitions was justified by an efficient energy transfer between the Tm(3+) ions. Microwave dielectric properties were investigated using the small perturbation theory. At a frequency of 5 GHz, the undoped material exhibits a dielectric permittivity of 21 and for thulium-doped Ta(2)O(5) samples it decreases to 18 for the highest doping concentration. Nevertheless, the dielectric losses maintain a very low value. (C) 2008 Elsevier Ltd. All rights reserved.

governo eletrônico como propiciador da reforma do estado: o caso do leilão reverso na web para licitação pública

A presente dissertação versa sobre o uso da Tecnologia da Informação e Comunicação aplicada aos processos de gestão pública à luz dos conceitos de eficácia, eficiência e accountabítlity. Para tanto, este estudo se funda sobre dois marcos teóricos. O primeiro trata do desenvolvimento científico-tecnológico e suas implicações na construção de uma sociedade resultante da interação da microeletrônica, da informatização e da telecomunicação. O segundo diz respeito à reforma do Estado Brasileiro, num contexto em que se discute a necessidade de torná-lo mais ágil, flexível e mais responsável perante a sociedade. Metodologicamente, valemo-nos do estudo de caso múltiplo, no qual analisamos o Pregão Eletrônico utilizado pelo Governo Federal para aquisição de bens e serviços nos moldes do leilão reverso do mercado de flores de Amsterdã. Especificamente, trata-se do Pregão 21/2001, realizado pelo Ministério da Previdência e Assistência Social, para compra de medicamentos. Este estudo contempla não só os diferentes aspectos do comércio eletrônico, como o procurement, mas também descreve o processo tradicional de licitações públicas. Ao final, concluímos que a adoção da tecnologia da informação aplicada à gestão pública, em especial como ferramenta para aquisição de bens e serviços, mostrouse eficiente ao promover uma redução de custos, tanto dos processos governamentais, quanto dos produtos adquiridos, fato extremamente relevante se considerarmos a realidade orçamentária brasileira. Ficou também comprovada a sua eficácia, evidenciada pela redução do tempo necessário à realização do procedimento, uma vez comparado ao processo tradicional de licitações pública. Por outro lado, podemos afirmar que a iniciativa amplia o grau de transparência das informações do setor público brasileiro, reconfigurando as relações EstadoSociedade.

Implementação de classificador de tarefas mentais baseado em EEG

BARBOSA, André F. ; SOUZA, Bryan C. ; PEREIRA JUNIOR, Antônio ; MEDEIROS, Adelardo A. D.de, . Implementação de Classificador de Tarefas Mentais Baseado em EEG. In: CONGRESSO BRASILEIRO DE REDES NEURAIS, 9., 2009, Ouro Preto, MG. Anais... Ouro Preto, MG, 2009

Estudo dos óxidos A2B2O7 e ABO3 a base de terras raras, para aplicações térmicas e catalíticas a altas temperaturas

Rare earth elements have recently been involved in a range of advanced technologies like microelectronics, membranes for catalytic conversion and applications in gas sensors. In the family of rare earth elements like cerium can play a key role in such industrial applications. However, the high cost of these materials and the control and efficiencies associated processes required for its use in advanced technologies, are a permanent obstacle to its industrial development. In present study was proposed the creation of phases based on rare earth elements that can be used because of its thermal behavior, ionic conduction and catalytic properties. This way were studied two types of structure (ABO3 and A2B2O7), the basis of rare earths, observing their transport properties of ionic and electronic, as well as their catalytic applications in the treatment of methane. For the process of obtaining the first structure, a new synthesis method based on the use of EDTA citrate mixture was used to develop a precursor, which undergone heat treatment at 950 ° C resulted in the development of submicron phase BaCeO3 powders. The catalytic activity of perovskite begins at 450 ° C to achieve complete conversion at 675 ° C, where at this temperature, the catalytic efficiency of the phase is maximum. The evolution of conductivity with temperature for the perovskite phase revealed a series of electrical changes strongly correlated with structural transitions known in the literature. Finally, we can establish a real correlation between the high catalytic activity observed around the temperature of 650 ° C and increasing the oxygen ionic conductivity. For the second structure, showed clearly that it is possible, through chemical processes optimized to separate the rare earth elements and synthesize a pyrochlore phase TR2Ce2O7 particular formula. This "extracted phase" can be obtained directly at low cost, based on complex systems made of natural minerals and tailings, such as monazite. Moreover, this method is applied to matters of "no cost", which is the case of waste, making a preparation method of phases useful for high technology applications

Wannier-function approach to electron states in superlattices under an electric field

Electron quasi-stationary states in a periodic semiconductor superlattice are calculated, as linear combinations of Wannier-Kohn functions, for different values of an electric field applied along the heterostructure. A comparison with an alternative approach, which is based on the localization of quasi-stationary states, is performed. (C) 2004 Elsevier Ltd. All rights reserved.

Nanohardness and contact angle of Si wafers implanted with N and C and Al alloy with N by plasma ion implantation

Surfaces of silicon wafers implanted with N and C, respectively, and aluminum 5052 implanted with N alone by plasma immersion ion implantation WHO were probed by a nanoindentor and analyzed by the contact-angle method to provide information on surface nanohardness and wettability. Silicon nitride and silicon carbide are important ceramic materials for microelectronics, especially for high-temperature applications. These compounds can be synthesized by high-dose ion implantation. The nanohardness of a silicon sample implanted with 12-keV nitrogen PIII (with 3 X 10(17) cm(-2) dose) increased by 10% compared to the unimplanted sample, in layers deeper than the regions where the formation of the Si,N, compound occurred. A factor of 2.5 increase in hardness was obtained for C-implanted Si wafer at 35 keV (with 6 X 10(17) cm(-2) dose), again deeper than the SiC-rich layer, Both compounds are in the amorphous state and their hardness is much lower than that of the crystalline compounds, which require an annealing process after ion implantation. In the same targets, the contact angle increased by 65% and 35% for N- and C-implanted samples, respectively. Compared to the Si target, the nitrogen PIII-irradiated Al 5052 (wish 15 keV) showed negligible change in its hydrophobic character after ion implantation. Its near-surface nanohardness measurement showed a slight increase for doses of 1 X 10(17) cm(-2). We have been searching for an AlN layer of the order of 1000 A thick, using such a low-energy PIII process, but oxide formation during processing has precluded its synthesis. (C) 2002 Elsevier B.V. B.V. All rights reserved.

Inovação tecnológica na indústria automobilística: características e evolução recente

O objetivo principal deste artigo é analisar as características básicas da evolução recente do processo de inovação tecnológica na indústria automobilística. A hipótese de trabalho é que estariam ocorrendo mudanças na intensidade do processo de inovação técnica nessa indústria. O ponto de partida é a observação de que, nos últimos anos, tem havido na indústria automotiva - provavelmente em decorrência da intensificação da concorrência setorial e de uma maior oportunidade tecnológica - tanto uma ampliação dos gastos em P&D quanto uma crescente incorporação da microeletrônica (nos produtos e nos processos produtivos). Finalmente, são feitas também algumas considerações procurando relacionar os resultados obtidos neste artigo com a discussão do processo de de-maturity (rejuvenescimento) industrial, proposto por Abernathy e outros autores.

Doping of polyaniline and derivatives induced by X-ray radiation

Thin films of chemically synthesized polyaniline and poly(o-methoxyaniline) were exposed to ionizing X-ray radiation and characterized by radiation induced conductivity measurements, ultraviolet-visible spectroscopy, electron paramagnetic resonance, electrical conductivity and solubility measurements. Samples irradiated in vacuum or dry Oxygen atmosphere did not have their electronic spectra changed. However, under humid atmosphere the energy of the excitonic transition was decreased and accompanied by a great conductivity increase. The results indicate that doping of polyaniline can be induced by X-ray radiation which might be of great interest for applications on lithography and microelectronics.

Influence of oxygen atmosphere on LiNbO3 thin films prepared by Pechini process

Thin films of lithium niobate were deposited on the Pt/Ti/SiO2 (111) substrates by the polymeric precursor method (Pechini process). Annealing in static air and oxygen atmosphere was performed at 500°C for 3 hours. The films obtained were characterized by X-ray diffraction, scanning electron microscopy and transmission electron microscopy. The dielectric constant, dissipation factor and resistance were measured in frequency region from 10 Hz to 10 MHz. Electrical characterizations of the films pointed to ferroelectricity via hysteresis loop. The influence of oxygen atmosphere on crystallization and properties of LiNbO3 thin films is discussed.

Anelastic spectroscopy in Al2O3

Engineering ceramics have found use in many applications, such as engine parts, ball bearings, artificial bone and hip replacements and gyroscopes, because of their good chemical inertness, hardness, high temperature stability and excellent wear resistance. Oxide ceramic may meet these demands. Alumina (Al2O3) ceramics offer a high potential for many engineering applications, such as wear- and/or corrosion-resistant components, and as material for substrates or housings in microelectronic devices. Alumina is used among other things for seal ring, draw-cones, guides, water mixing tapes, bearing parts, medical prostheses and cutting tools. Measurements of the elastic energy loss and modulus (anelastic spectroscopy) as a function of temperature can distinguish among the different atomic jumps, which occurs in the various phases or at different local ordering. In this paper, it is reported anelastic relaxation measurements in Al2O3 samples using commercial starch. These measurements were carried out in a torsion pendulum operating in frequencies around 40 Hz. The results shown strongly influence of the type of forming in the elastic modulus obtained by anelastic relaxation measurements.

Generating VHDL-AMS models of digital-to-analogue converters from MATLAB®/SIMULINK®

Today, the trend within the electronics industry is for the use of rapid and advanced simulation methodologies in association with synthesis toolsets. This paper presents an approach developed to support mixed-signal circuit design and analysis. The methodology proposed shows a novel approach to the problem of developing behvioural model descriptions of mixed-signal circuit topologies, by construction of a set of subsystems, that supports the automated mapping of MATLAB®/SIMULINK® models to structural VHDL-AMS descriptions. The tool developed, named MS 2SV, reads a SIMULINK® model file and translates it to a structural VHDL-AMS code. It also creates the file structure required to simulate the translated model in the System Vision™. To validate the methodology and the developed program, the DAC08, AD7524 and AD5450 data converters were studied and initially modelled in MATLAB®/ SIMULINK®. The VHDL-AMS code generated automatically by MS 2SV, (MATLAB®/SIMULINK® to System Vision™), was then simulated in the System Vision™. The simulation results show that the proposed approach, which is based on VHDL-AMS descriptions of the original model library elements, allows for the behavioural level simulation of complex mixed-signal circuits.

Critical parameter determination of sonic flow controller diamond microtubes and micronozzles

In this article, the authors measure throughput of sonic diamond microtubes and micronozzles that can work as passive gas flow controllers and flow meters under choking conditions. The behavior of the outlet pressure through the microdevices using an experimental setup with constant volume and constant temperature was determined in order to obtain the critical throughput, the critical mass flow rate, and the discharge coefficients of the diamond sonic microdevices. © 2007 American Vacuum Society.