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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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Polarization-controlled and single-transverse-mode vertical-cavity surface-emitting lasers with eye-shaped oxide aperture
摘要： We presented a single-transverse-mode and single-polarization vertical-cavity surface-emitting laser (VCSEL) with an eye-shaped oxide aperture, obtained by enhanced anisotropic oxidation of oxide layer. For apertures with dimensions of 2 ' 4.6 and 3 ' 6 μm2, the orthogonal polarization suppression ratio (OPSR) of the VCSEL was 22 and 19 dB, respectively. A single-mode suppression ratio (SMSR) of more than 25 dB at an output power of 0.5 mW was also achieved for the VCSEL with aperture dimension of 2 ' 4.6 μm2. We believe that the proposed method to realize the mode and polarization control of VCSELs has great potential in future applications. ? 2018 The Japan Society of Applied Physics
关键词： anisotropic oxidation,single-transverse-mode,VCSEL,single-polarization,eye-shaped oxide aperture
更新于2025-11-28 14:24:03
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Transmuting the blue fluorescence of hekates mesogens derived from tris(N-salicylideneaniline)s core via ZnS/ZnS:Mn2+ semiconductor quantum dots dispersion
摘要： In this paper, we present the preparation of nano-soft composites of ZnS and ZnS:Mn2+ quantum dots (QDs) with star shaped hekates mesogens (HMs) derived from tris(N-salicylideneaniline) core. The photophysical studies of the neat HMs and it's composites with QDs have been carried out as a function of temperature. The blue emission of HMs is found to be enhanced and red shifted in the presence of ZnS QDs. An induced yellow emission at 575 nm has been observed in HM-ZnS:Mn2+ QDs composite which is attributed to the 4T1 to 6A1 transition between the sp electrons of ZnS and d electrons of Mn2+ in the ZnS:Mn2+ QDs. The change in photophysical properties of HMs is analogous to the adscititious electron–proton interactions in hydrogen bonded environment after the dispersion of QDs. The large shift in N-H stretching and induction of a new S-H stretching band at 2734 cm 1 in the composites reveal the occurrence of intermolecular interactions between the HMs and QDs. Moreover, the presence of QDs signi?cantly changes the molecular orientation of the HMs as adduced by polarized optical microscopy. Tunability of the blue emission of HMs due to QDs dispersion depends on the degree of intermolecular interactions in the Guest-Host system. This study depicts its possible applications in the quantum dots based tunable photoluminescent displays.
关键词： Star-shaped mesogens,Photoluminescence,Quantum dots
更新于2025-11-14 15:32:45
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Preparation of ellipsoidal rod-shaped silica nanocomposite abrasives by Chromium ion/PEG200 induced method for sapphire substrates chemical mechanical polishing
摘要： Abrasive is vital to sapphire substrates chemical mechanical polishing and provides the most critical support for ?attening of sapphire. This work proposed a method to prepare ellipsoidal rod-shaped silica nanocomposite abrasives in order to increase the material removal rate and improve the surface roughness, which were applied to chemical mechanical polishing on sapphire substrates. Ellipsoidal rod-shaped silica nanocomposite abrasives were prepared by Chromium ion/PEG200 induced method. In this work, the synthesis process of ellipsoidal rod-shaped silica nanocomposite abrasives was discussed. As an inducing agent, Chromium compounds were bonded with two SiO2 particles via chemical bonds. And ellipsoidal rod-shaped silica nanocomposite abrasives were coated by PEG200 via hydrogen bonds. Results from X-ray photoelectron spectroscopy and time-of-?ight secondary ion mass spectroscopy revealed the occurrence of solid-state chemical reactions. The contact angle tests indicated the polishing liquid containing ellipsoidal rod-shaped silica nanocomposite abrasives had a good wettability. Ellipsoidal rod-shaped silica nanocomposite abrasives showed an excellent chemical mechanical polishing performance with a higher material removal and a lower surface roughness due to an excellent combination of chemical effect and mechanical effect occurred between ellipsoidal rod-shaped silica nanocomposite abrasives and sapphire substrates. A material removal model was built to describe the polishing behavior of ellipsoidal rod-shaped silica nanocomposite abrasives.
关键词： Polishing mechanism,Sapphire substrates,Ellipsoidal rod-shaped silica nanocomposite abrasives,Chemical mechanical polishing
更新于2025-11-14 15:27:09
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Oxygen-Deficient Dumbbell-Shaped Anatase TiO2-x Mesocrystals with Nearly 100% Exposed {101} Facets: Facile Synthesis, Growth Mechanism, and Enhanced Photocatalytic Performance
摘要： Developing hierarchical TiO2 superstructures with novel morphologies and intriguing photoelectric properties for utilizing solar energy is known to be an effective approach to alleviate the serious problems of environmental pollution. Herein, unique oxygen-deficient dumbbell-shaped anatase TiO2-x mesocrystals enclosed by ~100% {101} facets were readily synthesized via mesoscale transformation in the TiCl3-acetic acid mixed solution, followed by calcination under vacuum. These mesocrystals exhibited much higher photoreactivity toward removing the model pollutants of methyl orange and CrVI than tetragonal bipyramid anatase nanocrystals, anatase truncated mesocrystals built from truncated tetragonal bipyramid anatase nanocrystals, and anatase mesocrystals constructed by ~100% {101} facets exposed anatase nanocrystals, revealing that both the oxidation and reduction abilities of anatase TiO2 were simultaneously enhanced upon fabricating oxygen-deficient mesocrystalline architeture with ~100% exposed {101} facets. Further characterization illustrated that such an enhancement on photoreactivity was mainly due to the strengthened light absorption, boosted charge carrier separation, and ~100% exposed {101} facets of the oxygen-deficient dumbbell-shaped anatase mesocrystals. This work will be useful for guiding the synthesis of oxygen-deficient ordered superstructures of metal oxides with desired morphologies and exposed facets for promising applications in environmental remediation.
关键词： photocatalytic performance,{101} facet,oxygen-deficient,anatase mesocrystals,dumbbell-shaped
更新于2025-09-23 15:23:52
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A dual-band circularly polarized microstrip patch antenna with a cross shaped slot for 0.92/2.45 GHz RFID applications
摘要： A double-band circularly polarized (CP) patch antenna is presented. It is a round patch antenna with a cross-shape slot. Furthermore, it radiates wide beam CP waves at two radio-frequency identification (RFID) bands: 920 MHz and 2.45 GHz. Slightly oblate round patch antennas generally radiate CP waves and have resonant frequencies at two or more harmonic bands. To radiate wide beam CP waves at two bands, a cross-shape slot was made on a round patch antenna in this study. As a result, the cross-shape slot has made it possible for a 920 MHz round patch antenna to simultaneously radiate wide beam CP waves at 2.45 GHz which is higher than a harmonic frequency.
关键词： circularly polarized,RFID,cross shaped slot,double-band,patch antenna
更新于2025-09-23 15:23:52
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[IEEE 2018 25th IEEE International Conference on Image Processing (ICIP) - Athens, Greece (2018.10.7-2018.10.10)] 2018 25th IEEE International Conference on Image Processing (ICIP) - Tree-Shaped Sampling Based Hybrid Multi-Scale Feature Extraction for Texture Classification
摘要： Efficiency, distinctiveness and robustness are three main goals for feature extractors in application of texture classification. In this paper, a new feature extractor is designed which aims to achieve these three goals simultaneously. The contributions are threefold. Firstly, a tree-shaped multi-scale sampling structure is proposed to acquire points distributed along two circles and one octagon. Secondly, four histogram vectors are obtained by quantizing the sampling values through a hybrid strategy. In order to suppress the noise, mean filtering is used as a preprocessing step and the four vectors are concatenated to form the discriminant vector. Thirdly, experiments are conducted on different datasets with several well-known feature extractors. The results show that the proposed method improves the classification accuracy effectively and robustly, while has a moderate complexity. The source code is available at: https://github.com/madd2014/TSSHM.
关键词： texture classification,Feature extraction,multi-scale structure,tree-shaped sampling
更新于2025-09-23 15:23:52
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Combined effects of unsteady wake and free-stream turbulence on turbine blade film cooling with laid-back fan-shaped holes using PSP technique
摘要： Detailed film cooling effectiveness distribution for a gas turbine blade under the effects of unsteady wakes and oncoming free-stream turbulence intensities was obtained using pressure sensitive paint (PSP) technique. Tests were performed on a linear cascade at Reynolds number of 3.85 × 10^5 based on the blade chord at cascade exit. Upstream unsteady wakes were simulated using a spoke-wheel type wake generator. The test blade has three rows of compound angled cylindrical film holes at the leading edge, five rows of laid-back fan-shaped holes on the pressure surface and three rows of laid-back fan-shaped holes on the suction surface. The wake Strouhal number was varied from 0 to 0.36 and three mass flux ratios were determined. The oncoming free-stream turbulence intensities are 2.7% and 26.9%, respectively. Results show that the effect of the mass flux ratio on the film cooling effectiveness decreases under the high turbulence intensity and unsteady wake conditions. In most regions of the blade surface, the film cooling effectiveness decreases with the increase of wake Strouhal number, and the free-stream turbulence superimposed on the unsteady wake reduces the film cooling effectiveness further. The effect of the unsteady wake decreases under the high free-stream turbulence conditions.
关键词： Turbulence intensity,Film cooling effectiveness,PSP,Wake,Mass flux ratio,Turbine blade,Strouhal number,Laid-back fan-shaped hole
更新于2025-09-23 15:23:52
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Electrochromic 2,4,6-triphenyl-1,3,5-triazine based esters with electron donor-acceptor structure
摘要： Ten tripod-shaped electrochromic materials (compound 1–10) were designed and synthesized by esterification of 4,4',4''-s-triazine-2,4,6-triyl-tribenzoic acid with different alcohols and phenols. These materials have a 2,4,6-triphenyl-1,3,5-triazine core and three ester side arms, forming an electron donor–π-acceptor structure. The electrochemical and optical properties of 1–10 were characterized by cyclic voltammetry and ultraviolet–visible spectroelectrochemistry. The conjugated structure of 1–10 markedly influenced their electrochemical properties. Electrochromic devices containing some of these compounds (1, 2, 4, 5, and 10) displayed intense color changes, fast switching times (<2 s), high optical contrast (>60%), good switching stability, high optical density (>1.0), and high coloring efficiency (>1000 cm2 C?1). The colored state of these devices strongly depended on the conjugated structure of the tripod-shaped component. Short chain lengths (compounds 1 and 2) and electron-donating groups (compounds 4, 5, 8, and 10) were beneficial to electrochromic properties, whereas a longer chain length (compound 3) and electron-withdrawing groups (compounds 6 and 9) adversely affected electrochromic properties.
关键词： Electron donor-acceptor structure,2,4,6-Triphenyl-1,3,5-triazine based esters,Tripod-shaped electrochromic materials,Electrochromic devices
更新于2025-09-23 15:23:52
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An AIEgen-based fluorescent probe for highly selective and specific imaging of lipid droplets in L02 and HepG2 cells
摘要： Lipid droplets (LDs), as dynamic organelles, are associated with physiologically and pathologically metabolic processes. Especially, in human liver cancer cells (HepG2 cells) the lipid metabolism shows significant difference by comparing with the human normal liver cell (L02 cells). In this work, a new highly selective and specific fluorescent probe TPA-SD for the detection of LDs has been rationally designed and easily prepared from triphenylamine and salicylaldehyde, which possesses aggregation-induced emission (AIE) and excited state intramolecular proton transfer characteristics (ESIPT). Ideal probes for LDs imaging require high concentration accumulation of fluorophores in LDs and lack of self-quenching in the aggregated state, so the AIE property is necessary. TPA-SD can successfully and specifically accumulate in LDs, thus facilitating clearly distinguishing L02 cells from HepG2 cells according to obvious difference in the number of dot-shaped LDs marked by TPA-SD. The dot-shaped LDs in the HepG2 cells is found to be obviously more than that in the L02 cells. Moreover, the spatial distribution of LDs could be identified by TPA-SD. The results indicate TPA-SD possesses great potential in imaging and diagnosis of LDs-related diseases.
关键词： fluorescent probe,aggregation-induced emission,dot-shaped LDs number,lipid droplets (LDs) imaging
更新于2025-09-23 15:23:52