ABSTRACT
Phase imaging is an important measurement method in optical metrology, and phase extraction is one of its essential components. A method using one-frame dual-wavelength interferometry (DWI) for fast phase extraction is proposed. Using this method, the Hilbert transform (HT) is applied twice to a wavelength-multiplexed interferogram to obtain two images. The HT is then applied twice to the sum of the squares of these two images. The synthetic wavelength phase can then be obtained. Compared with other common multiple-frame DWI methods, the proposed approach requires only one multiplexed interferogram and does not have to consider parameter changes in interferograms of different frames. Furthermore, the proposed method was determined to require the least calculation time, and the simulation and experimental results confirmed its high accuracy and efficiency. It suggests that the proposed method is suitable for real-time measurements.
ABSTRACT
Protonic ceramic fuel cells (PCFCs) have been proved as an efficient energy converter at intermediate temperatures. To accelerate the kinetics of the proton-involved oxygen reduction reaction (p-ORR), developing efficient and durable cathodes is of great importance for improving PCFCs. In this work, a new triple-layered Ruddlesden-Popper (R-P) structure oxide, Sr3 EuFe2.5 Co0.5 O10-δ (3-SEFC0.5 ), was developed as a potential single-phase cathode for PCFCs, showing high oxygen non-stoichiometry and desirable structural thermal stability. By employing this highly active and stable single-phase cathode, the PCFC demonstrated unprecedented low polarization resistances and exceptionally great peak power densities, which were approximately 0.030â Ω cm2 and 900â mW cm-2 measured at 700 °C, respectively. These findings not only manifest the effectiveness of optimal doping in improving the structural stability and electrocatalytic activity in the multi-layered perovskite family, but also highlight the great potential of using multi-layered R-P series oxides as highly active and durable catalysts for PCFCs.
ABSTRACT
In this study, a simultaneous dual-wavelength phase-shifting interferometry system using two reference arms was built, and a simple phase retrieval method for the system with blind phase shifts was proposed using five phase-shifted interferograms. First, the unknown phase shifts were controlled independently to separate the information of single wavelength, which can be calculated directly by using the Euclidean matrix norm algorithm. Second, a wrapped phase of a single wavelength was obtained using a three-step phase-shifting algorithm. Finally, a continuous phase of a synthetic wavelength was obtained. The simulation and experimental results indicated the feasibility and greater accuracy of the proposed method. Moreover, the strict requirement of the phase shifter was eliminated because of the use of arbitrary and unknown phase shifts, thereby making experimental operation easier.
ABSTRACT
A series of La/Ce-codoped Bi2O3 composite photocatalysts were fabricated via hydrothermal-calcination process. The as-prepared products were intensively characterized by some physicochemical characterizations like N2 physical adsorption, X-ray powder diffraction (XRD), scanning electron microscope (SEM), transmission electron microscope (TEM), UV-Vis diffuse reflectance (UV-Vis DRS), Fourier transform infrared spectroscopy (FT-IR), photoelectrochemical measurements, and photoluminescence (PL) spectroscopy. The characterization results indicated that La and Ce doping induced obvious crystal phase transformation in Bi2O3, from monoclinic to tetragonal phase. La and Ce codoping also gave rise to the obvious synergetic effects, e.g., the lattice contraction of Bi2O3, the decrease of crystal size and the increase of surface area. The photocatalytic performance of the prepared catalysts was evaluated by removal of dye acid orange II with high concentration under visible light irradiation. Results showed that La/Ce-codoped Bi2O3 displayed much higher photocatalytic performance than that of bare Bi2O3, single La or Ce doped Bi2O3 samples. The superior photocatalytic activity was mainly attributed to the improved texture and surface properties and the synergistic effects of La and Ce codoping on suppressing the recombination of photo-generated electrons (e-) and holes (h+).
