Abstract:WO3/Ag composite film photoanodes were synthesized by hydrothermal combined electrodeposition method. Characterization of samples was conducted by scanning electron microscope (SEM) and X-ray diffraction (XRD), which showed that WO3/Ag composite films had been synthesized. Diffuse reflectance spectra show WO3/Ag composite film has more strong absorption than WO3 film under simulated visible light irradiation. Electrochemical impedance spectroscopy shows WO3/Ag composite film photoanode enhances charge transfer efficiency compared with WO3 film. WO3/Ag composite film photoanodes show higher photocurrent and photoelectric catalytic activity than WO3 film, and the WO3/Ag composite film obtained by depositing Ag nanoparticles at 50 s (WO3/Ag-50) shows the highest photocurrent and photoelectric photoelectric catalytic activity. Meanwhile, the photoelectric catalytic activity of the composite film is higher than their direct photocatalytic and electric catalytic activity. The higher photocurrent and photoelectric catalytic activity of the WO3/Ag composite film photoanodes are attributed to the surface plasmon resonance effect of Ag nanoparticles and Schottky junction effect at the WO3/Ag interface.

Abstract:In this paper, the influence of laser wavelength instability, polarization fading and phase fluctuation on local heterodyne detection wavelength scanning Brillouin optical time domain reflectometer (WS-BOTDR) is theoretically analyzed, and a local heterodyne detection WS-BOTDR system is built for experimental verification. The experimental results show that with the increase of sensing distance, the adverse effect of laser wavelength instability, polarization fading and phase fluctuation on local heterodyne detection WS-BOTDR is gradually aggravated, which will lead to the broadening and distortion of the wavelength power spectrum (WPS), resulting in large errors in demodulated Brillouin central wavelength (BCW) and temperature. The average temperature measurement errors at the positions of 1 km, 5 km, 9 km non-heating section and 9.45 km heating section are 1.76 °C, 3.42 °C, 3.89° C and 4.3 °C, respectively.

Abstract:A high-sensitivity low-temperature sensor based on Fabry-Pérot interferometer (FPI) is fabricated and experimentally demonstrated in this letter. The FPI air cavity is fabricated by splicing a single-mode optical fiber (SMF) with a glass capillary tube partially filled with ultraviolet (UV) glue. Due to the high coefficient of thermal expansion of UV-glue, the sensor can obtain high sensitivity. Experimental results show that the sensor has a temperature sensitivity of −3.753 4 nm/℃ in the temperature range of −4—4 ℃, and the linearity is 0.999. The engineering performance of the sensor is tested by simulating the frozen soil environment. The proposed sensor has high sensitivity and good temperature response. The sensor structure is compact and simple, low cost and has potential application in the cryogenic detection environment.

Abstract:A biological solution concentration sensor based on a side-polished fiber (SPF) assisted fluid system is presented. The birefringence properties of the asymmetrically filled fluid in this structure and the relationship between the concentration of the biological solution and the refractive index are theoretically analyzed. It was found that the interference peaks had red-shifted with increasing concentration. A sensing sensitivity of 1.387 1×104 nm·mL/mol at 14.68×10-4 mol/mL was achieved within the experimental range after different concentrations of arginine solutions were injected into the sensing system. This sensing system can also be applied to measure the concentration of other biological solutions, providing the feasibility of real-time detection of biological solutions.

Abstract:Nowadays, tandem structures have become a valuable competitor to conventional silicon solar cells, especially for perovskite over silicon, as metal halides surpassed Si with tunable bandgaps, high absorption coefficient, low deposition, and preparation costs. This led to a remarkable enhancement in the overall efficiency of the whole cell and its characteristics. Consequently, this expands the usage of photovoltaic technology in various fields of applications not only under conventional light source spectrum in outdoor areas, i.e., AM1.5G, but also under artificial light sources found indoors with broadband intensity values, such as Internet of things (IoTs) applications to name a few. We introduce a numerical model to analyze perovskite/Si tandem cells (PSSTCs) using both crystalline silicon (c-Si) and hydrogenated amorphous silicon (a-Si:H) experimentally validated as base cells. All proposed layers have been studied with J-V characteristics and energy band diagrams under AM1.5G by using SCAPS-1D software version 3.7.7. Thereupon, the proposed architectures were tested under various artificial lighting spectra. The proposed structures of Li4Ti5O12/CsPbCl3/MAPbBr3/CH3NH3PbI3/Si recorded a maximum power conversion efficiency (PCE) of 25.25% for c-Si and 17.02% for a-Si:H, with nearly 7% enhancement concerning the Si bare cell in both cases.

Abstract:In this paper, the effects of different concentrations of complexing agent (ammonia) on the surface morphology, composition, structure and photoelectric properties of CdZnS films were studied. The results of X-ray diffraction (XRD), scanning electron microscopy (SEM) and UV-visible spectrum showed that the surface morphology of the films became worse and the content of zinc decreased significantly with the increase of ammonia concentration. The crystalline phase of CdZnS films was not influenced by the ammonia concentration. Because the film has good absorbance, transmittance greater than 70% and band gap width between 3.5 eV and 3.07 eV, it is suitable to be used as a buffer layer for solar cells. CdS, ZnO and Zn(OH)2 were found in the precipitates at the bottom of the solution, and the formation of these precipitates affected the properties of the CdZnS films.

Abstract:In this paper, the effects of different laser powers, repetition rates, and spot overlaps on the surface roughness, micromorphology, and Vickers hardness of rusted AH36 steel were researched in the rust removal experiment of fiber pulse laser on the marine steel surface. Then, the mechanical properties, corrosion resistance, and metallographic microstructure of the surface of samples after laser cleaning were analyzed. The experimental results show that when the processing parameters were the laser power of 40 W, the repetition rate of 110 kHz, and the spot overlap of 50%, the rust removal effect on AH36 steel was the best, and it met the cleanliness standard of marine steel coating. Moreover, its Vickers hardness, mechanical properties, corrosion resistance, and repainting properties were superior to those of the original substrate.

Abstract:Due to the applications in the fields of optical communication, neuronal imaging, and medical endoscopic imaging, the study of multimode fiber (MMF) wavefront transmission is crucial for image reconstruction and wavefront generation in user terminals. State of art studies in this area focus on high-quality image reconstruction and wavefront shaping. Besides the way of imaging reconstruction, the performances of image reconstruction and wavefront shaping are also dependent on system and environment parameters. This paper numerically analyzes the influence of key factors, such as the numerical aperture (NA) of the near-end objective lens of the MMF imaging system, the charge coupled device (CCD) noise of the acquired image, and the ambient temperature at close distances. This work would help to the optimization of the MMF-based imaging system and provide a theoretical basis for potential applications in optical communication systems, neuron imaging and endoscopic diagnosis.

Abstract:Aero-optical imaging deviation is a kind of optical effect, aiming at a conical aircraft. This paper analyzes the influence of the aircraft on the imaging deviation with the change of altitude and line-of-sight angle. In this paper, the relationships between imaging deviation and altitude as well as line-of-sight angle are analyzed, and the coupling relationship between altitude and line-of-sight angle is studied. We give the imaging deviation results of 5°—75° line-of-sight angle. The analysis shows that when the line-of-sight angle is in the range of 5°—35°, the imaging deviation is more sensitive, while the line-of-sight angle is in the range of 35°—75°, the imaging deviation is relatively flat, and the imaging deviation does not gradually decrease with the increase of line-of-sight angle, but there is a turning point in the middle of 5°—75°. The imaging deviation decreases first and then increases, and the turning point of line-of-sight angle is closely related to height.

Abstract:With the expansion of smart grid and Internet of things (IoT) technology, edge computing has a wide variety of applications in these domains. The criteria for real-time monitoring and accuracy are particularly high in the field of online real-time monitoring of electricity lines. Based on edge technology, high-quality real-time monitoring can be performed for transmission lines using image processing techniques. Therefore, we propose an image denoising method, which can learn clean images using a stream-based generative model. The stream model uses a two-stage approach in the network to handle the different training periods of denoising separately. Experimental results show that the proposed method has good denoising performance.

Abstract:Implicit polynomial (IP) fitting is an effective method to quickly represent two-dimensional (2D) image boundary contour in the form of mathematical function. Under the same maximum degree, the fractional implicit polynomial (FIP) can express more curve details than IP and has obvious advantages for the representation of complex boundary contours. In existing studies, algebraic distance is mainly used as the fitting objective of the polynomial. Although the time cost is reduced, there are problems of low fitting accuracy and spurious zero set. In this paper, we propose a two-stage neural network with differentiable geometric distance, which uses FIP to achieve mathematical representation, called TSEncoder. In the first stage, the continuity constraint is used to obtain a rough outline of the fitting target. In the second stage, differentiable geometric distance is gradually added to fine-tune the polynomial coefficients to obtain a contour representation with higher accuracy. Experimental results show that TSEncoder can achieve mathematical representation of 2D image boundary contour with high accuracy.