Eduardo Ono

Real-time optical fibre sensor for hydro-alcoholic solutions

The fast determination of ethanol–water concentration in alcohol distillation plants is a primordial requirement to preserve the quality and reduce production losses. The present research proposes an optical fibre sensor for the measurement of hydro-alcoholic concentration in liquids based on the Fresnel reflection principle. The reflection intensities of ethanol samples with 0–100% of water content were measured at different temperatures for 1310 nm and 1550 nm wavelengths. Calibration curves were prepared by fitting the experimental data and implemented in a computer algorithm. According to the functional tests, the sensor is capable of identifying samples with less than 1% error on concentration and providing practically real-time analysis.

Application of an Optical Fiber Sensor on the Determination of Sucrose and Ethanol Concentrations in Process Streams and Effluents of Sugarcane Bioethanol Industry

In this paper, the measurement of process streams and effluents from the sugar-ethanol industry using an optical fiber sensor based on the Fresnel reflection principle is reported. Firstly, binary sucrose-water and ethanol-water solutions with predetermined concentrations were measured for calibration purposes. Secondly, the coproducts from various processing stages were analyzed in order to identify the sucrose or ethanol content. The measured data were processed by an artificial neural network model, which correlated the reflected intensity values to the sample concentration. The absolute error was calculated by a comparison between the nominal concentration values obtained by the plant laboratory analysis and the sensor response, yielding errors ≤ 3& wt% and ≤ 5.1 vol% for the sucrose and ethanol contents, respectively. The fiber sensor has the potential to provide reliable results even for samples with more complex compositions than pure sucrose or ethanol solutions, with perspectives of application on the several stages of the plant facility.

Measurement of sucrose and ethanol concentrations in process streams and effluents of sugarcane bioethanol industry by optical fiber sensor

The measurement of process streams and effluents from sugar-ethanol industry by using optical fiber sensor based on Fresnel reflection principle is reported. Firstly, binary sucrose-water and ethanol-water solutions were measured in order to determine the calibration curves. Secondly, the co-products from various processing stages were analyzed in order to identify the sucrose or ethanol concentration. The absolute error was calculated by comparison between the nominal concentration values obtained by plant laboratory analysis and the sensor response, yielding errors ≤ 5 wt% and ≤ 5 vol% for sucrose and ethanol content, respectively. The fiber sensor provided reliable results even for samples with more complex compositions than pure sucrose or ethanol solutions, with perspectives of application on the several stages of the plant facility.

Automation for monitoring of the refractive index profile of vapor-phase-deposited soot preforms for optical fiber

The vapor-phase axial deposition process is currently one of the most advantageous methods to produce preforms for optical fibers, due to its high efficiency and reduced production cost. However, this method has great difficulty in determining the refractive index profile, since it is influenced by too many process parameters. In this work, an automation system to determine the refractive index profile by monitoring the preform deposition surface profile during the soot preform deposition stage is presented. Based on a previous study that showed a strong correlation between these two profiles, an automation system was developed in LABVIEW to monitor the deposition surface profile during the preform deposition stage in order to estimate the preform germanium doping profile and refractive index profile, as well as a theoretical study to develop this system in order to minimize the performance impairment. As a result, not only preforms with a predetermined index profile were produced but also a reduction in production cost was obtained by decreasing the number of preform rejects.

Real-time monitoring of fermentation process applied to sugarcane bioethanol production

The application of a Fresnel-based fiber sensor on real-time monitoring of the fermentation process in bioethanol production is reported. The fiber was placed inside the bioreactor, and experiments were conducted by using glucose solution and sugarcane syrup as substrates for fermentation. When the sugar is completely consumed, there is no production of ethanol, causing the sample concentration to become constant, as well as the reflected light intensity. Therefore, the sensor can be used to predict the ideal moment to terminate the process. The results were confirmed by additional laboratory analysis, making this an alternative technology for optimization of bioethanol production.

Correlation study between VAD preform deposition surface and Germanium doping profiles

The refractive index profile of germanium doped preforms for optical fibers is determined by the radial distribution of germanium concentration. Knowing that there is a correlation between the germanium doping profile and the deposition surface profile of vapor-phase axial deposition (VAD) preforms, the study of this correlation has been carried out in order to estimate, indirectly, the refractive index profile of VAD preforms for optical fibers during the deposition stage. This correlation was studied through the parameterization of the preform deposition surface using two parameters: the power law index profile that best fits the preform bottom profile (/spl alpha/) and the axial distance from the bottom tip to a reference height (h). A range of values of these parameters to produce VAD preforms with standard and special doping profiles has been presented. Preforms with triangular index profile can be fabricated with /spl alpha/ and h values of about 2.0 and 5.0 mm, respectively, and preforms with parabolic index profiles can be produced with /spl alpha/ and h values of about 2.0 and 4.0 mm, respectively.

Optical Classification of Quartz Lascas by Artificial Neural Networks

A gradation method based on quartz lascas (lumps) transparency level is proposed. The samples were irradiated by transmitting light, and the images histograms were processed by artificial neural networks. Additionally, the results were compared to conventional classification methods, including density and visual analysis. The network designed with backpropagation architecture using 4 hidden layers of 10 neurons yielded to a relative error <24% in relation to manual classification, indicating a good agreement to the miners criteria. Furthermore, the implementation of competitive learning with 5 neurons resulted in correct discrimination of samples regarding their optical characteristics with a completely non-subjective approach.

Effect of the Nanostructure Control on the Novel Optical Properties of Silica Photonic Glass Synthesized by VAD Method

This research reports the development of high homogeneity silica glass for photonic components synthesized by the VAD (Vapor-phase Axial Deposition) method. Structural radial homogeneity of silica soot were characterized by scanning electron microscopy (SEM) and small angle X-ray scattering (SAXS). It was established a relationship with the refractive index homogeneity, n, and the birefringence of consolidated boules characterized through interferometry, optical spectrometry, and polarization spectrophotometry. By controlling the silica soot nanostructure during the deposition stage, a material with high radial homogeneity of refractive index of 1 ppm and birefringence of 2 nm/cm can be synthesized.

Simulation Study of Deposition Parameters for Elliptical- Shaped Preforms by VAD for Polarization-Maintaining Fibers

A novel fabrication method of elliptical‐shaped preforms for polarization‐maintaining fibers, developed using the VAD technology and based on the variation of the perform rotation velocity from zero to a maximum velocity in repeated cycles of 180°, allows modifying and controlling the preform geometry by choosing the process parameters, such as the maximum rotation velocity and the delay time on zero velocity positions. The effect of each process variable was studied through a mathematical modeling and simulation of the methodology, comprising a simplified model of the soot deposition process. Results demonstrated that preforms with high elllipticity can be obtained by increasing the delay time or decreasing the maximum rotation velocity. It was also observed that the effect of the delay time is more noticeable on the preform geometry than the contribution of maximum velocity. These facts were confirmed when compared to real deposition results, using a VAD chamber with gases fluxes set to 2.33×10−6 m3/s (...

Study of Bubbles Elimination in Silica Glass Produced by Flame Fusion from Brazilian Natural Quartz Powder

Silica glass is a fundamental material for the high technology industry due to its physical properties. This material is widely used in the semiconductor, chemical and optical industry. For applications in the optical industry and special lamps, it is necessary that the silica has a reduced content of bubbles and high optical transmittance in the wavelength regions of visible and medium ultraviolet (200 nm – 300 nm). Silica glass samples were produced by the flame fusion Verneuil Method of Brazilian commercial natural quartz powder and imported high purity commercial powder. An acid leaching procedure of the national quartz powder was introduced before the fusion in order to decrease bubbles concentration. The results were compared with the silica glass produced with imported quartz powder and a commercial silica glass used for the fabrication of special lamps, showing an excellent feasibility of application of Brazilian natural quartz to produce high value added silica glass.