High sensitivity fiber optic angular displacement sensor and its application for detection of ultrasound

Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)

Optimal placement of piezoelectric sensor/actuators for smart structures vibration control

Smart material technology has become an area of increasing interest for the development of lighter and stronger structures that are able to incorporate actuator and sensor capabilities for collocated control. In the design of actively controlled structures, the determination of the actuator locations and the controller gains is a very important issue. For that purpose, smart material modeling, modal analysis methods, and control and optimization techniques are the most important ingredients to be taken into account. The optimization problem to be solved in this context presents two interdependent aspects. The first is related to the discrete optimal actuator location selection problem, which is solved in this paper using genetic algorithms. The second is represented by a continuous variable optimization problem, through which the control gains are determined using classical techniques. A cantilever Euler-Bernoulli beam is used to illustrate the presented methodology.

Bond strength durability of a resin composite on a reinforced ceramic using various repair systems

Objectives. This study compared the durability of repair bond strength of a resin composite to a reinforced ceramic after three repair systems.Methods. Alumina-reinforced feldspathic ceramic blocks (Vitadur-alpha(R)) (N=30) were randomly divided into three groups according to the repair method: PR-Porcelain Repair Kit (Bisco) [etching with 9.5% hydrofluoric acid + silanization + adhesive]; CJ-CoJet Repair Kit (3M ESPE) [(chairside silica coating with 30 mu m SiO2 + silanization (ESPE(R)-Sil) + adhesive (Visio(TM)-Bond)]; CL-Clearfil Repair Kit [diamond surface roughening, etching with 40% H3PO4 + Clearfil Porcelain Bond Activator + Clearfil SE Bond)]. Resin composite was photo-polymerized on each conditioned ceramic block. Non-trimmed beam specimens were produced for the microtensile bond strength (mu TBS) tests. In order to study the hydrolytic durability of the repair methods, the beam specimens obtained from each block were randomly assigned to two conditions. Half of the specimens were tested either immediately after beam production (Dry) or after long-term water storage (37 degrees C, 150 days) followed by thermocyling (12,000 cycles, 5-55 degrees C) in a universal testing machine (1 mm/min). Failure types were analyzed under an optical microscope and SEM.Results. mu TBS results were significantly affected by the repair method (p=0.0001) and the aging conditions (p=0.0001) (two-way ANOVA, Tukey's test). In dry testing conditions, PR method showed significantly higher (p < 0.001) repair bond strength (19.8 +/- 3.8 MPa) than those of CJ and CL (12.4 +/- 4.7 and 9.9 +/- 2.9, respectively). After long-term water storage and thermocycling, CJ revealed significantly higher results (14.5 +/- 3.1 MPa) than those of PR (12.1 +/- 2.6 MPa) (p < 0.01) and CL (4.2 +/- 2.1 MPa) (p < 0.001). In all groups when tested in dry conditions, cohesive failure in the composite accompanied with adhesive failure at the interface (mixed failures), was frequently observed (76%, 80%, 65% for PR, CJ and CL, respectively). After aging conditions, while the specimens treated with PR and CJ presented primarily mixed failure types (52% and 87%, respectively), CL group presented mainly complete adhesive failures at the interface (70%).Significance. Hydrolytic stability of the repair method based on silica coating and silanization was superior to the other repair strategies for the ceramic tested. (C) 2009 Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.

Dissipative dynamics of matter-wave solitons in a nonlinear optical lattice

Dynamics and stability of solitons in two-dimensional (2D) Bose-Einstein condensates (BEC), with one-dimensional (1D) conservative plus dissipative nonlinear optical lattices, are investigated. In the case of focusing media (with attractive atomic systems), the collapse of the wave packet is arrested by the dissipative periodic nonlinearity. The adiabatic variation of the background scattering length leads to metastable matter-wave solitons. When the atom feeding mechanism is used, a dissipative soliton can exist in focusing 2D media with 1D periodic nonlinearity. In the defocusing media (repulsive BEC case) with harmonic trap in one direction and nonlinear optical lattice in the other direction, the stable soliton can exist. Variational approach simulations are confirmed by full numerical results for the 2D Gross-Pitaevskii equation.

Cold-atom systems and the scaling limit

With perspective to applications of cold-atom systems, some aspects of few-body physics at very low energies will be reviewed. By exploring the possibilities of varying the two-body interaction via the Feshbach resonance mechanism, some recent results are reported for condensed systems in optical lattices.

Determinação de parâmetros físico-químicos com um sensor potenciométrico sensível ao íon p-aminobenzoato

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Carbon dioxide efflux in a rhodic hapludox as affected by tillage systems in southern Brazil

Os solos agrícolas podem atuar como dreno ou fonte de C atmosférico, dependendo do sistema de manejo adotado. Este estudo foi desenvolvido em experimento de longa duração (22 anos), durante o período de 30 dias do outono, com o objetivo de avaliar o impacto de sistemas de preparo de solo (preparo convencional-PC e plantio direto-PD) nas emissões de C-CO2 de um Latossolo Vermelho distrófico, em Cruz Alta, RS. As emissões de C-CO2 do solo foram avaliadas com câmaras dinâmica (Flux Chamber 6400-09, Licor) e estática (com captação em solução alcalina), imediatamente após a colheita da soja. A temperatura e a umidade do solo foram registradas, concomitantemente com as emissões de C-CO2, por meio de sensor de temperatura e TDR manual, respectivamente, integrantes do Licor-6400. Estimou-se que, em 30 dias, uma quantidade equivalente a menos de 30 % do C aportado pelos resíduos de soja foi emitida na forma de C-CO2. As emissões de C-CO2 no solo em PD foram similares às emissões do solo em PC, independentemente do tipo de câmara utilizada. Diferenças entre sistemas de preparo quanto à emissão de C-CO2, avaliadas com a câmara dinâmica, foram verificadas somente a curto prazo (leituras diárias), com o PD apresentando maiores emissões do que o PC no início do período experimental e menores no final. A câmara dinâmica foi mais eficiente do que a estática em captar as alterações das emissões de C-CO2 em função da variação da temperatura e a porosidade preenchida por água (PPA) no solo em PD, as quais explicaram 83 e 62 % das emissões de C-CO2, respectivamente. O fator Q10, que avalia a sensibilidade da emissão de C-CO2 à temperatura do solo, foi estimado em 3,93, indicando alta sensibilidade da atividade microbiana à temperatura do solo durante o outono. As emissões de C-CO2 registradas no solo em PD com a câmara estática foram correlacionadas às da câmara dinâmica, porém com valores subestimados em relação àquela notadamente nos maiores valores de fluxo. em condições de baixa temperatura e PPA, o preparo de solo induziu limitado incremento de emissão de C-CO2.

Evaluation of digital optical density of bone repair in rats medicated with ketoprofen

O objetivo deste estudo foi avaliar a influência do cetoprofeno sobre o processo de reparação óssea em tíbias de ratos, por meio da análise da densidade óptica digital. Vinte ratos da linhagem Wistar foram divididos em 2 grupos: um grupo controle (sem tratamento) e um grupo tratado com cetoprofeno. Os procedimentos experimentais consistiram de: anestesia, cirurgia, administração do cetoprofeno e exame radiográfico. As imagens radiográficas foram adquiridas empregando-se o sensor digital Visualix GX-S-HDI™ e um aparelho de raios X. As radiografias foram realizadas nos períodos baseline (inicial), 7, 14, 21 e 30 dias pós-operatório, sendo a densidade óptica (DO) avaliada por meio do sistema Vix winTM 1.4. Os valores médios da leitura da do obtidos foram analisados estatisticamente por meio de ANOVA e teste de Tukey com nível de significância de 5%. No grupo controle, houve diferença estatisticamente significante (p=0,001) entre o tempo e a DO, enquanto no grupo tratado com cetoprofeno a diferença não foi estatisticamente significante (p=0,100). O grupo controle apresentou as menores proporções de do (%) no 1º e 7º dias e as maiores proporções de do (%) no 14º, 21º e 30º dias, com diferença estatisticamente significante (p=0,001). Não houve diferença estatisticamente significante (p=0,100) entre as proporções médias de do (%) no grupo tratado, independentemente do período de avaliação. Os achados deste trabalho sugerem que houve influência do cetoprofeno sobre o processo de reparo ósseo, uma vez que na primeira semana o medicamento proporcionou aumento na densidade óptica e provocou atraso na neoformação óssea após o 21º dia.

Fluorometric fiber optic drop sensor for atmospheric hydrogen sulfide

A fluorometric technique based on a liquid drop excited from its interior by an optical fiber is described for the measurement of low concentrations of atmospheric hydrogen sulfide (H2S). A drop of alkaline fluorescein mercuric acetate (FMA) solution is suspended in a flowing air sample stream and serves as a renewable sensor. An optical fiber contained within the conduit that forms the drop, brings in the excitation beam; the fluorescence emission is measured by an inexpensive photodiode positioned close to the drop. As H2S in the sample is collected by the alkaline drop, it reacts rapidly with FMA resulting in a significant decrease in fluorescence intensity, proportional to the concentration of H2S sampled. The chemistry of this uniquely selective reaction has been well established for many years, the present technique permits a simple fast inexpensive near real-time measurement with very little reagent consumption. Even without prolonged sampling/preconcentration steps, limits of detection (LODs) in the double digit ppbv range is readily attainable. (C) 1997 Elsevier B.V. B.V.

Well-conditioned robust observer for detection of family systems components

A new concept of fault detection and isolation using robust observation for systems with random noises is presented. The method selects the parameters from components that may fault during the process and constructs well conditioned robust observers, considering sensors faults. To isolate component failures via robust observation, a bank of detection observers is constructed, where each observer is only sensitive to one specified component failure while robust to all other component failures.

Comparison of simulated periodontal bone defect depth measured in digital radiographs in dedicated and non-dedicated software systems

Objectives: To compare simulated periodontal bone defect depth measured in digital radiographs with dedicated and non-dedicated software systems and to compare the depth measurements from each program with the measurements in dry mandibles.Methods: Forty periodontal bone defects were created at the proximal area of the first premolar in dry pig mandibles. Measurements of the defects were performed with a periodontal probe in the dry mandible. Periapical digital radiographs of the defects were recorded using the Schick sensor in a standardized exposure setting. All images were read using a Schick dedicated software system (CDR DICOM for Windows v.3.5), and three commonly available non-dedicated software systems (Vix Win 2000 v.1.2; Adobe Photoshop 7.0 and Image Tool 3.0). The defects were measured three times in each image and a consensus was reached among three examiners using the four software systems. The difference between the radiographic measurements was analysed using analysis of variance (ANOVA) and by comparing the measurements from each software system with the dry mandibles measurements using Student's t-test.Results: the mean values of the bone defects measured in the radiographs were 5.07 rum, 5.06 rum, 5.01 mm and 5.11 mm for CDR Digital Image and Communication in Medicine (DICOM) for Windows, Vix Win, Adobe Photoshop, and Image Tool, respectively, and 6.67 mm for the dry mandible. The means of the measurements performed in the four software systems were not significantly different, ANOVA (P = 0.958). A significant underestimation of defect depth was obtained when we compared the mean depths from each software system with the dry mandible measurements (t-test; P congruent to 0.000).Conclusions: the periodontal bone defect measurements in dedicated and in three non-dedicated software systems were not significantly different, but they all underestimated the measurements when compared with the measurements obtained in the dry mandibles.

Optical properties of remotely doped parabolic quantum wells

This work is intended to report on optical measurements in a parabolic quantum well with a two dimensional-three dimensional electron gas. Photoluminescence results show broad spectra which are related to emission involving several subbands on conduction band with the fundamental level of the valence band. This assumption is based on the behavior of the PL peak position and the full width at half maximum in the function of the incident power intensity. (C) 2002 Elsevier B.V. B.V. All rights reserved.

Small-angle X-ray scattering study of the smart thermo-optical behavior of zirconyl aqueous colloids

The smart thermo-optical systems studied here are based on the unusual thermoreversible sol-gel transition of zirconyl chloride aqueous solution modified by sulfuric acid in the molar ratio Zr/SO4:3/1. The transparency to the visible light changes during heating due to light scattering. This feature is related to the aggregates growth that occurs during gelation. These reversible changes can be controlled by the amount of chloride ions in solution. The thermoreversible sol-gel transition temperature increases from 323 to 343 K by decreasing the molar ratio Cl/Zr from 7.0 to 1.3. In this work the effect of the concentration of chloride ions on the structural characteristics of the system has been analyzed by in situ SAXS measurements during the sol-gel transition carried out at 323 and 333 K. The experimental SAXS curves of sols exhibit three regions at small, medium and high scattering vectors characteristics of Guinier, fractal and Porod regimes, respectively. The radius of primary particles, obtained from the crossover between the fractal and Porod regimes, remains almost invariable with the chloride concentration, and the value (4 Angstrom) is consistent with the size of the molecular precursor. During the sol-gel transition the aggregates grow with a fractal structure and the fractal dimensionality decreases from 2.4 to 1.8. This last value is characteristic of a cluster-cluster aggregation controlled by a diffusion process. Furthermore, the time exponent of aggregate growth presents values of 0.33 and 1, typical of diffusional and hydrodynamic motions. A crossover between these two regimes is observed.

Effect of Different Solvent Ratios (Water/Ethylene Glycol) on the Growth Process of CaMoO4 Crystals and Their Optical Properties

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)