We propose a combined pump-probe optical method to investigate heat diffusion properties of solids. We demonstrate single-shot simultaneous laser-induced thermoelastic surface displacement of metals ...detected by concurrent measurements using photothermal mirror and interferometry. Both methods probe the surface displacement by analyzing the wavefront distortions of the probe beams reflected from the surface of the sample. Thermoelastic properties are retrieved by transient analysis in combination with numerical description of the thermoelastic displacement and temperature rise in the sample and in the surrounding air. This technique presents a capability for material characterization that can be extended to experiments for quantitative surface mapping.
In this work we present our findings performing low frequency Raman measurements over temperature in a tellurite-tungstate glass sample. The spectra could be fitted by using only two log-Gaussians, ...which suggests that quasi-elastic light scattering is negligible. The positions of the peaks have the same temperature behavior, being the higher frequency one refereed as Boson Peak in literature. The similar temperature behavior and depolarization ratio indicates that the peaks may have the same origin, being linked to the transversal and longitudinal vibrations of some unit.
One of the most significant materials in a solar panel is the glass, which provides transparency, UV protection as well as mechanical and chemical resistance. In this work, we describe the production ...of prototypes of four solar modules made using borosilicate, zinc-tellurite, Pr3+ doped zinc-tellurite, and float glass as cover materials. The performance of these prototypes was evaluated under a solar simulator, and a device was developed to monitor all prototypes under real conditions. A comparison between indoor and outdoor measurements shows that outdoor results are fundamental to evaluate the performance of modified solar modules as the ones considered in this study. In addition, we demonstrate the fundamental role played by the refractive index of cover glasses in the performance of the prototypes, and discuss how this feature could be explored to achieve enhanced devices, as well as other benefits that may arise from this field of research.
•Four glasses were used to build prototypes of solar photovoltaic panels.•An affordable tool to monitor the power output of the prototypes is demonstrated.•The performance of these devices during an entire day was measured.•Reflection losses due to the high refractive index of tellurites were quantified.•The development of practical spectral converters is discussed.
This work aimed to investigate and compare the composition and the physicochemical properties of 18 different sources of edible vegetable oils. A systematic study on the correlation between ...composition and physical properties was performed using Fourier Transform Infrared (FTIR) Spectroscopy and fatty acid chromatographic analysis. Principal component analysis of FTIR spectra is performed to classify edible oils concerning their physical properties. The results demonstrate the potentiality of the method associated with multivariate statistics analysis as powerful, fast, and non-destructive tools for characterization and quality control of edible vegetable oils.
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•The correlation of composition and physicochemical properties of edible vegetable oils•Chromatographic and spectroscopic techniques associated with multivariate statistics analysis•Unsaturated fatty acids are related to mass density, dynamic viscosity, oxidative stability index and refractive index.•These techniques allow predicting oil properties, helping in the characterization and quality control of vegetable oils.•Direct correlation of the PCA components with the set of information about composition and physical properties of the oils
Ce:Y3Al5O12 and Eu:Y3Al5O12 ceramics were obtained by combining high-energy ball milling and inert-gas flow sintering. The photoluminescence properties of Ce:Y3Al5O12 ceramics were identical to those ...reported for Ce:Y3Al5O12 single crystals, while the Eu:Y3Al5O12 luminescence spectra were attributed to a larger concentration of Eu2+ in relation to Eu3+ ions as a direct consequence of the synthesis protocol. The Eu:Y3Al5O12 photoluminescence emission and excitation spectra are very similar to those of Ce:Y3Al5O12, attesting the feasibility for applying Eu2+:Y3Al5O12 ceramics as white-light phosphors.
► Eu:YAG and Ce:YAG ceramics for white-light applications. ► Eu:YAG and Ce:YAG ceramics processed by combining high-energy ball milling and reactive sintering under inert gas flow. ► Coexistence of Eu2+ and Eu3+ as luminescent ions and broad band white-light emission in YAG ceramics. ► Broad band white-light emission in ceramic materials.
We propose improvements to a time-resolved gas volume meter based on bubble count. This type of sensor is dedicated to small-scale laboratory applications, usually related to gas production in ...biological processes. We highlight the cost reduction and simplification in the manufacturing method of this type of sensor, when compared to the manufacturing method. To achieve this purpose, the sensor’s glass body was replaced by plastic material, a detection system based on the detection of capacitance variation was introduced and without contact with the measuring fluid, the data acquisition system was built based on small single-board computer and a graphical user interface were developed in an open source programming language. Theses innovations are significant for scientific research institutions, with limited financial resources, to uses gas volume sensors that can be applied in the investigation of biological processes such as alcoholic fermentation, biogas and biohydrogen generation.
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•Improvements in the gas volume measurement based on bubble counting.•Simplification of the sensor construction method by replacing glass with plastic material.•Detection system without contact with the gas and free from the action of oxidation and external interference.•Time-resolved determination of gas volume in anaerobic biological processes.
In this paper, it is proposed and numerically tested a 4 −THz guard-band-less integrated all-optical wavelength converter (iAOWC) with two four-wave mixing (FWM) stages. The nonlinear media used in ...each stage is a waveguide with a tellurite core that is buried into a SiO2 substrate. The core is shaped as two interleaved spirals connected in their centers by two arcs of a circle to minimize bend loss. The iAOWC can continuously shift a 4 −THz WDM bandwidth from the C- to the L-band and vice versa. In the physical layer simulations, 80×28−GBaud, as DP-QPSK and DP-16QAM, 50-GHz-WDM signals were propagated, respectively, through typical distances found in ultra-long-haul and long-haul transmission systems. For up to four wavelength conversions, the penalties imposed on the signals bit-error-ratios by the iAOWCs were negligible. In the network layer simulations, blocking probabilities were estimated in the CORONET and PANEUR topologies supposing an incremental traffic scenario. Physical layer results were fundamental for the parameters (route lengths, wideband conversion, and spectral shift) considered in the network layer analysis. All network links could carry up to 160 wavelengths that extended from C- to L-band. It is shown that by using an iAOWC with bandwidth of 4-THz instead of 1-THz, both with the same spectral shift capability, to match the blocking probabilities achieved with OEOWCs, this would lead to a reduction of 50% and 40% in the number of required devices for the CORONET and PANEUR topologies, respectively. Finally, this is the first time that it is reported a joint analysis of the physical and network layers regarding the impact of wideband wavelength conversion on the performance of optical networks, specially using an integrated all-optical device and under real-world traffic scenarios.
•A wideband integrated all-optical wavelength converter was numerically tested.•Wavelength converter can operate with dual-polarization WDM signals.•Wavelength converter imposes negligible penalty on the WDM signals BER.•Physical and network layers analysis on the impact of wavelength conversion.•The wider the wavelength converter band, the fewer the required devices.
On the dynamics of bubbles in boiling water Ribeiro, H.V.; Mendes, R.S.; Lenzi, E.K. ...
Chaos, solitons and fractals,
2011, 2011-01-00, Letnik:
44, Številka:
1
Journal Article
Recenzirano
Odprti dostop
► We devote this work to investigate the bubbles dynamics in boiling water. ► A simple experiment of laser scattering was designed to obtain dynamical features. ► Correlations and non-exponential ...distributions were found. ► A simple model was able to describe several aspects of the system.
We investigate the dynamics of many interacting bubbles in boiling water by using a laser scattering experiment. Specifically, we analyze the temporal variations of a laser intensity signal which passed through a sample of boiling water. Our empirical results indicate that the return interval distribution of the laser signal does not follow an exponential distribution; contrariwise, a heavy-tailed distribution has been found. Additionally, we compare the experimental results with those obtained from a minimalist phenomenological model, finding a good agreement.
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