STGMN: A gated multi-graph convolutional network framework for traffic flow prediction

Applied Intelligence - Accurate traffic flow prediction is crucial for the development of intelligent transportation. It can not only effectively avoid traffic congestion and other traffic...     

Cesium lead halide perovskite triangular nanorods as high-gain medium and effective cavities for multiphoton-pumped lasing

High-performance multiphoton-pumped lasers based on cesium lead halide perovskite nanostructures are promising for nonlinear optics and practical frequency upconversion devices in integrated photonics.However,the performance of such lasers is highly dependent on the quality of the material and cavity,which makes their fabrication challenging.Herein,we demonstrate that cesium lead halide perovskite triangular nanorods fabricated via vapor methods can serve as gain media and effective cavities for multiphoton-pumped lasers.We observed blue-shifts of the lasing modes in the excitation fluence-dependent lasing spectra at increased excitation powers,which fits well with the dynamics of Burstein-Moss shifts caused by the band filling effect.Moreover,efficient multiphoton lasing in CsPbBr3 nanorods can be realized in a wide excitation wavelength range (700-1,400 nm).The dynamics of multiphoton lasing were investigated by time-resolved photoluminescence spectroscopy,which indicated that an electron-hole plasma is responsible for the multiphoton-pumped lasing.This work could lead to new opportunities and applications for cesium lead halide perovskite nanostructures in frequency upconversion lasing devices and optical interconnect systems.     

Tuning the temperature coefficient of resonant frequency for 8-layer twinned hexagonal perovskite Ba<Subscript>8</Subscript>ZnTa<Subscript>6</Subscript>O<Subscript>24</Subscript> ceramics

High-Q dielectric materials ilmenite MgTiO₃, columbite MgNb₂O₆ and cubic perovskite Ba₃NiTa₂O₉ with negative temperature coefficient of resonant frequency (τ _f ) were selected as candidates for compensating the τ _f of hexagonal perovskite Ba₈ZnTa₆O₂₄. X-ray diffraction data shows that Ba₈ZnTa₆O₂₄ coexists with Ba₃NiTa₂O₉ but is not compatible with MgTiO₃ and MgNb₂O₆ at high temperature. The τ _f for the mixed hexagonal/cubic perovskite Ba₈ZnTa₆O₂₄–Ba₃NiTa₂O₉ system is tunable via the temperature compensation effect and its quality factor may be improved via annealing the ceramics at high temperature to enhance the cation ordering in the cubic component. Permittivity ε _r  ~ 22–25, Q×f > 30,000 GHz and tunable τ _f within ±10 ppm/°C were achieved in the range of about 50–80 wt% Ba₃NiTa₂O₉ for the hexagonal/cubic perovskite composite Ba₈ZnTa₆O₂₄–Ba₃NiTa₂O₉ ceramics, which is suitable for the application as dielectric resonators and filters.     

Comparison of gas sensing properties based on hollow and porous α-Fe<Subscript>2</Subscript>O<Subscript>3</Subscript> nanotubes

Hollow and porous α-Fe₂O₃ nanotubes were successfully synthesized by single nozzle electrospinning method followed by annealing treatment. The crystal structures and morphologies of the as-prepared materials were characterized by X-ray diffraction and scanning electron microscopy, respectively. The as-prepared materials were applied to construct gas sensor devices which gas sensing properties were further investigated. The obtained results revealed that porous α-Fe₂O₃ nanotube gas sensors exhibit a markedly enhanced gas sensing performance compared with hollow α-Fe₂O₃ nanotube gas sensors, which was about three times higher to 100 ppm acetone at 240 °C. Interestingly, hollow and porous α-Fe₂O₃ nanotube gas sensors both showed fast response–recovery time and good selectivity, but the porous ones possessed the shorter recovery time. The improved properties could be attributed to the unique morphology of porous nanotubes. Thus, further improvement of performance in metal-oxide-semiconductors materials could be realized by preparation the unique porous structures of nanotubes. Moreover, it is expected that porous metal-oxide-semiconductors nanotubes could be further design as promising candidates for gas sensing materials.     

La<Subscript>1−x</Subscript>Ag<Subscript>x</Subscript>FeO<Subscript>3</Subscript>/halloysites nanocomposite with enhanced visible light photocatalytic performance

La_1?xAg_xFeO₃/halloysites nanotubes (HNTs) nanocomposite was synthesized by sol–gel method. It was characterized by X-ray diffraction, transmission electron microscope, Fourier transform infrared spectroscopy and UV–visible diffused reflectance spectroscopy measurements. The photo-activity of the La_1?xAg_xFeO₃/HNTs nanocomposite was evaluated via degradation of methylene blue (MB) under visible-light irradiation. The results showed that the HNTs with unique pore structure favored the adsorption of organic molecules. Adequate Ag⁺ doping improved the absorption ability for visible light. The La_0.95Ag_0.05FeO₃/HNTs demonstrated the best photocatalytic performance, which achieved as high as 99 % for MB degradation exposed 2 h irradiation. However,further increasing of Ag⁺ doping gradually reduced the photocatalytic activity. The nanocomposite catalyst showed outstanding recyclability after eight cycles which still remained up to 90 %.     

多模态隐喻视角下的产品设计理论方法研究

目的研究多模态隐喻在产品设计中的设计方法。方法归纳多模态隐喻在产品设计中的表现形式,深入分析其在产品设计中的创建机制与方法。结论提出以产品图像、动作、声音、空间为元素的多模式的产品设计创建方法。     

强磁场对硅锰铸钢于A_1点附近等温珠光体相变的影响

通过开展12 T强磁下硅锰铸钢(50Si_2Mn_3)于A_1点温度附近不同等温时间的热处理试验,并对比强磁场与无磁场条件下等温珠光体相变试验结果,研究了磁场对珠光体转变量及组织形貌的影响。研究表明,对于50Si_2Mn_3在A1点以下较高温度范围内,强磁场可缩短珠光体相变的孕育期,促进硅锰铸钢珠光体转变,使其转变量明显增加;强磁场能够提高珠光体转变临界点,使50Si_2Mn_3在A1点以上等温过程中能够发生珠光体相变。     

Performance of porous asphalt mixture with various additives

The objective of this study is to evaluate the approaches to improve the durability and strength of the porous asphalt through laboratory testing. Porous asphalt specimens were prepared using three types of binders: high-viscosity binder (HVB), PG76-22 and PG70-22. Various additives: fibre, hydrated lime and DBS polymer, were utilised in the porous asphalt. Comprehensive laboratory tests, including strength test, binder draindown test, Cantabro abrasion test, moisture susceptibility test, rutting test, thermal stress restrained sample test, and permeability test, were conducted. It is found that HVB significantly improved the overall performance of the porous asphalt; DBS additive improved its high-temperature performance, but lowered the cracking resistance at low temperature as well as the durability; fibre enhanced its durability and anti-cracking performance at low temperature; hydrated lime improved its moisture stability while weakening its durability. It is concluded that HVB and polyester fibre should be used in all porous asphalt; DBS additive is good for porous asphalt in high-temperature areas, and hydrated lime can be added to porous asphalt in rainy areas.     

Ultrathin 2D Zirconium Metal–Organic Framework Nanosheets: Preparation and Application in Photocatalysis

Synthesizing ultrathin 2D metal–organic framework nanosheets in high yields has received increasing research interest but remains a great challenge. In this work, ultrathin zirconium‐porphyrinic metal–organic framework (MOF) nanosheets with thickness down to ≈1.5 nm are synthesized through a pseudoassembly–disassembly strategy. Owing to the their unique properties originating from their ultrathin thickness and highly exposed active sites, the as‐prepared ultrathin nanosheets exhibit far superior photocatalysis performance compared to the corresponding bulk MOF. This work highlights new opportunities in designing ultrathin MOF nanosheets and paves the way to expand the potential applications of MOFs.