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Research on the “∞”-shaped laser scanning welding process for aluminum alloy
摘要： To solve the problems of poor quality and insu?cient joint strength of aluminum alloy weld, a laser scanning welding test platform for aluminum alloy was built. Taking the butt welding of 5052 aluminum alloy with 5 mm and 3 mm thick specimens as the research objects, the study of a “∞”-shaped laser scanning welding process was conducted, and the similarities and di?erences between the welding process and that of single pass laser welding were compared. The in?uence of “∞”-shaped laser scanning welding parameters on the weld formation was investigated by the factor variable method. The change of the surface morphology and dynamic evolution of the molten pool was observed by a high-speed camera system. The optimal combination of the welding parameters was obtained by an orthogonal test. The research showed that the “∞”-shaped laser scanning welding pool had good stability and a good weld quality. Under suitable welding parameters, the length and width of the molten pool could be increased signi?cantly compared with those of the single pass laser welding. The growth rate of the length and width could reach 110.19% and 57.69%, respectively. The surface of the weld was evenly distributed with dense ?sh scales, and the porosity was less than 1%. The tensile strength of the specimen could reach 205.242 MPa, which was 93% that of the base metal; the topography of fracture was full of dimples, and the metallographic structure of the weld was ?ne and distributed with equiaxed dendrites.
关键词： Weld appearance,Weld performance,Laser technique,“∞”-shaped laser scanning welding,Molten pool characteristics
更新于2025-11-28 14:24:20
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A comparison between induction pre-heating and induction post-heating of laser-induction hybrid welding on S690QL steel
摘要： In this paper, the di?erences of microstructure and performance of S690QL steel between induction pre-heating laser-induction hybrid welding (LIHW) and post-heating LIHW were compared via scanning electron microscope (SEM), energy-dispersive spectroscopy (EDS), electrical back-scattered di?raction (EBSD), and mechanical machines. The t8/5 values of both pre-heating and post-heating LIHW joints were shown to increase with inductor output power increasing from 60% to 80% and 100%, and each temperature curve of the post-heating LIHW weld center (WC) and heat-a?ected zone (HAZ) has two peak values. Through experimental and theoretical analyses, pre-heating LIHW joints were determined to mainly contain ferrite, bainite and little martensite, while the post-heating LIHW joints have more bainite. Except for the 80% inductor output power post-heating sample, the microstructures demonstrate dispersing phenomena, as well as weld defects. With increasing pre-heating LIHW inductor output powers, the proportion of ferrite rises, martensite and bainite contents decrease, and dislocation pileup occurs; these will lead to the decrease of microhardness and an increase in plasticity. However, in post-heating LIHW joints, the amounts of ferrite and martensite show a decreasing tendency, and the proportion of bainite tends to increase. The fracture pattern of pre-heating LIHW joints and post-heating LIHW joints is shown to be a dimple fracture, and the pre-heating LIHW joints have a better tensile strength and toughness. Thus, compared with post-heating LIHW, pre-heating LIHW is shown to be superior.
关键词： Performance,Microstructure,Laser-induction hybrid welding
更新于2025-11-28 14:24:20
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Tuning Bandgap of Mixed-Halide Perovskite for Improved Photovoltaic Performance Under Monochromatic-Light Illumination
摘要： Organic–inorganic halide perovskites have emerged as promising materials for optoelectronic devices. This paper focuses on a new application field for perovskite materials as monochromatic-light conversion devices. First the optical properties of organic–inorganic perovskite semiconductors with bandgaps varying from near-infrared to visible at room temperature are presented. Two types of hybrid organic–inorganic mixed-halide perovskites, (FAPbI3)x(MAPbBr3)1-x and FA0.85MA0.15Pb(IxBr1-x)3, are adopted for bandgap tuning, an approximate linear variation of bandgaps with the x value is obtained. The relationship between thin film composition and device performance are investigated. Based on the results of the above bandgap tuning, two kinds of devices with bandgap near the wavelength of 683 nm are characterized under monochromatic-light illumination. A conversion efficiency of up to 40% under 60 mW cm?2 monochromatic-light illumination is achieved. The results confirm that the perovskite films exhibit sharp optical absorption edge, enabling highly efficient monochromatic-light conversion device.
关键词： monochromatic-light,hybrid mixed-halide perovskites,bandgap tuning,photovoltaic performance
更新于2025-11-25 10:30:42
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Accelerating single molecule localization microscopy through parallel processing on a high-performance computing cluster
摘要： Super-resolved microscopy techniques have revolutionized the ability to study biological structures below the diffraction limit. Single molecule localization microscopy (SMLM) techniques are widely used because they are relatively straightforward to implement and can be realized at relatively low cost, e.g. compared to laser scanning microscopy techniques. However, while the data analysis can be readily undertaken using open source or other software tools, large SMLM data volumes and the complexity of the algorithms used often lead to long image data processing times that can hinder the iterative optimization of experiments. There is increasing interest in high throughput SMLM, but its further development and application is inhibited by the data processing challenges. We present here a widely applicable approach to accelerating SMLM data processing via a parallelized implementation of ThunderSTORM on a high-performance computing (HPC) cluster and quantify the speed advantage for a four-node cluster (with 24 cores and 128 GB RAM per node) compared to a high specification (28 cores, 128 GB RAM, SSD-enabled) desktop workstation. This data processing speed can be readily scaled by accessing more HPC resources. Our approach is not specific to ThunderSTORM and can be adapted for a wide range of SMLM software.
关键词： super-resolved microscopy,high-performance computing,Automated image analysis
更新于2025-11-21 11:24:58
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Luminescence and anion recognition performance of mononuclear Eu(III) complexes with N- and O- donor pyridine derivatives
摘要： A series of Eu(III) complexes with pyridine-2-carboxamide (PCA), pyridine-2-carboxaldoxime (PCAO), pyridine-2,3-dicarboxylic anhydride (PDCA) or pyridine-2-methanol (PM) as primary ligands and 4,4′-dimethoxy-2,2′-bipyridine (DMBP) as ancillary ligand were synthesized. The interaction between the ligands and complexes were confirmed by FT-IR study. The complexes were abbreviated as [Eu(PCA)3DMBP].Cl3 (C1), [Eu(PCAO)3DMBP].Cl3 (C2), [Eu(PDCA)3DMBP].Cl3 (C3) and [Eu(PM)3DMBP].Cl3 (C4). Optical studies were done by UV–vis spectroscopy and PL spectroscopy. The highest intrinsic luminescent quantum yield (53.42%) and lifetime value (1456 μs) were found for C3. Lowest quantum yield was exhibited by C2. Anion sensing studies of all the complexes were done by UV–vis and PL spectroscopy and it was observed that complex C1 showed remarkable change in optical properties upon addition of F? and HSO4? ions. Thus C1 can be used as optical sensor for F? and HSO4? ions. The FQD for F? and HSO4? ions were found to be 6.55 and 3.58 respectively for C1.
关键词： Sensing performance,Antenna effect,Hydrogen bonding,Optical sensor,Lifetime decay
更新于2025-11-21 11:18:25
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Enhanced photocatalytic performance of TiO2 NTs decorated with chrysanthemum-like BiOI nanoflowers
摘要： The BiOI nanosheets/chrysanthemum-like nanoflowers were successfully deposited on the surface of TiO2 nanotube arrays (TiO2 NTs) by the successive ionic layer adsorption and reaction (SILAR) method, and the morphology and visible light response of samples with different SILAR deposition cycles were investigated in detail. The as-prepared BiOI/TiO2 NTs significantly enhanced photoelectrocatalytic (PEC) activity for the removal of Methyl orange (MO), Rhodamine B (RhB), Methylene blue (MB) and Cr(VI). The as-prepared Sample-7 with chrysanthemum-like nanostructures showed the high visible light photocurrent density of 120.06 μA/cm2, photovoltage of ?203.61 mV/cm2, PEC efficiencies of 45%, 62%, 79% and 77% for the removal of MO, RhB, MB and Cr(VI), respectively. The high PEC performances could be ascribed to the excellent visible light response and charge carrier transportation in chrysanthemum-like BiOI nanoflowers. By further probing the charge separation and transportation behaviors, the experiments of the energy band structure and active species trapping were carried out. A possible p-n heterojunction photocatalytic mechanism was proposed, which not only benefited the efficient separation of photogenerated electrons but also demonstrated the advanced capacity for the PEC removal of organic dyes and heavy metal ions.
关键词： BiOI,Photoelectrochemical performance,TiO2 nanotube arrays,Nanoflowers
更新于2025-11-19 16:56:35
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Enhanced piezoelectricity of a PVDF-based nanocomposite utilizing high-yield dispersions of exfoliated few-layer MoS2
摘要： Piezoelectric polymer composite ?lms have attracted extensive attention due to their comprehensive characteristics such as low cost, good ?exibility, mechanical property and excellent processability. Among the known polymers, poly (vinylidene ?uoride) (PVDF) is an ideal piezoelectric polymer because the β-crystalline form of PVDF has the highest polarization per unit cell. However, initial PVDF mostly su?ers from the lack of a β phase, restricting its potential applications. Few-layer MoS2 is predicted to be strongly piezoelectric owing to the opposite orientations of adjacent atomic layers. In this work, we report an e?cient approach to enhance the piezoelectric property of PVDF-based nanocomposites by combining few-layer MoS2 with PVDF. The product yield for few-layer MoS2 reached a value as high as 83.3% via a unique liquid-exfoliation technique. For a few-layer MoS2/PVDF composite ?lm with 1 wt.% few-layer MoS2, a high piezoelectric performance enhancement of 360% was achieved compared with the initial PVDF ?lm. In addition, due to the intrinsic lubrication of MoS2, the highest elongation of the piezoelectric composite ?lm was found to be four times higher than that of the pure PVDF ?lm.
关键词： Composite,Film,Piezoelectric performance,Few-layer
更新于2025-11-14 17:28:48
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Hierarchical TiO <sub/>2</sub> microspheres composed with nanoparticle-decorated nanorods for the enhanced photovoltaic performance in dye-sensitized solar cells
摘要： Hierarchical TiO2 microspheres composed of nanoparticle-decorated nanorods (NP-MS) were successfully prepared with a two-step solvothermal method. There were three benefits associated with the use of NP-MS as a photoanode material. The decoration of nanoparticles improved the specific surface area and directly enhanced the dye loading ability. Rutile nanorods serving as electron transport paths resulted in fast electron transport and inhibited the charge recombination process. The three-dimensional hierarchical NP-MS structure supplied a strong light scattering capability and good connectivity. Thus, the hierarchical NP-MS combined the beneficial properties of improved scattering capability, dye loading ability, electron transport and inhibited charge recombination. Attributed to these advantages, a photoelectric conversion efficiency of up to 7.32% was obtained with the NP-MS film-based photoanode, resulting in a 43.5% enhancement compared to the efficiency of the P25 film-based photoanode (5.10%) at a similar thickness. Compared to traditional photoanodes with scattering layers or scattering centers, the fabrication process for single layered photoanodes with enhanced scattering capability was very simple. We believe the strategy would be beneficial for the easy fabrication of efficient dye-sensitized solar cells.
关键词： electron transport,dye-sensitized solar cells,solvothermal method,Hierarchical TiO2 microspheres,photovoltaic performance
更新于2025-11-14 17:04:02
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Improved photovoltaic performance of perovskite solar cells by utilizing down-conversion NaYF <sub/>4</sub> :Eu <sup>3+</sup> nanophosphors
摘要： Perovskite solar cells assembled with titanium dioxide electron transport layer exhibited brilliant photovoltaic properties due to titanium dioxide having a high electron mobility, appropriate energy level alignment and easy fabrication procedure. However, inherent instability exists in titanium dioxide-based perovskite solar cells because of the ultraviolet photocatalytic activity of titanium dioxide. This results in recombination at the interface of titanium dioxide/perovskite. In this report, the down-conversion nanocrystals film made of europium-doped sodium yttrium fluoride was deposited on the non-conducting side of the conducting glass. The down-conversion nanocrystal layer could absorb high energy ultraviolet photons and converted them to visible light. The layer not only extended the spectral response range for perovskite solar cells but also alleviated the photocatalytic activity of titanium dioxide. The perovskite solar cells with the down-conversion nanocrystals film generated average power conversion efficiency yield of 19.99%, which is much better than that of the device without the down-conversion nanocrystals film (16.99%). The best power conversion efficiency for the device with the down-conversion nanocrystals film was 20.17%. In addition, perovskite solar cells with the down-conversion nanocrystals film showed a small hysteresis.
关键词： titanium dioxide,down-conversion,NaYF4:Eu3+ nanophosphors,photovoltaic performance,perovskite solar cells
更新于2025-11-14 17:04:02
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Efficient Dye-Sensitized Solar Cells Composed of Nanostructural ZnO Doped with Ti
摘要： Photoanode materials with optimized particle sizes, excellent surface area and dye loading capability are preferred in good-performance dye sensitized solar cells. Herein, we report on an efficient dye-sensitized mesoporous photoanode of Ti doped zinc oxide (Ti-ZnO) through a facile hydrothermal method. The crystallinity, morphology, surface area, optical and electrochemical properties of the Ti-ZnO were investigated using X-ray photoelectron spectroscopy, transmission electron microscopy and X-ray diffraction. It was observed that Ti-ZnO nanoparticles with a high surface area of 131.85 m2 g?1 and a controlled band gap, exhibited considerably increased light harvesting efficiency, dye loading capability, and achieved comparable solar cell performance at a typical nanocrystalline ZnO photoanode.
关键词： bandgap energy,dye-sensitized solar cell,photovoltaic performance,Ti doped ZnO
更新于2025-11-14 17:04:02