Nanjing University of Aeronautics and Astronautics

About: Nanjing University of Aeronautics and Astronautics is a education organization based out in Nanjing, China. It is known for research contribution in the topics: Computer science & Microstructure. The organization has 33704 authors who have published 37321 publications receiving 438855 citations. The organization is also known as: Nanjing College of Aviation Industry & Nanjing Aeronautical Institute.

Strain-dependent electronic and magnetic properties of MoS2 monolayer, bilayer, nanoribbons and nanotubes.

Abstract: We investigate the strain-dependent electronic and magnetic properties of two-dimensional (2D) monolayer and bilayer MoS(2), as well as 1D MoS(2) nanoribbons and nanotubes using first-principles calculations. For 2D monolayer MoS(2) subjected to isotropic or uniaxial tensile strain, the direct band gap of MoS(2) changes to an indirect gap that decreases monotonically with increasing strain; while under the compressive strain, the original direct band gap is enlarged first, followed by gap reduction when the strain is beyond -2%. The effect of isotropic strain is even stronger than that of uniaxial strain. For bilayer MoS(2) subjected to isotropic tensile strain, its indirect gap reduces monotonically to zero at strain about 6%; while under the isotropic compressive strain, its indirect gap increases first and then reduces and turns into direct gap when the strain is beyond -4%. For strained 1D metallic zigzag MoS(2) nanoribbons, the net magnetic moment increases slightly with axial strain from about -5% to 5%, but drops to zero when the compressive strain is beyond -5% or increases with a power law beyond 5%. For 1D armchair MoS(2) nanotubes, tensile or compressive axial strain reduces or enlarges the band gap linearly, and the gap can be fully closed for nanotubes with relatively small diameter or under large tensile strain. For zigzag MoS(2) nanotubes, the strain effect becomes nonlinear and the tensile strain can reduce the band gap, whereas compressive strain can initially enlarge the band gap and then decrease it. The strain induced change in projected orbitals energy of Mo and the coupling between the Mo atom d orbital and the S atom p orbital are analyzed to explain the strong strain effect on the band gap and magnetic properties.

Learning Feature Pyramids for Human Pose Estimation

Abstract: Articulated human pose estimation is a fundamental yet challenging task in computer vision. The difficulty is particularly pronounced in scale variations of human body parts when camera view changes or severe foreshortening happens. Although pyramid methods are widely used to handle scale changes at inference time, learning feature pyramids in deep convolutional neural networks (DCNNs) is still not well explored. In this work, we design a Pyramid Residual Module (PRMs) to enhance the invariance in scales of DCNNs. Given input features, the PRMs learn convolutional filters on various scales of input features, which are obtained with different subsampling ratios in a multibranch network. Moreover, we observe that it is inappropriate to adopt existing methods to initialize the weights of multi-branch networks, which achieve superior performance than plain networks in many tasks recently. Therefore, we provide theoretic derivation to extend the current weight initialization scheme to multi-branch network structures. We investigate our method on two standard benchmarks for human pose estimation. Our approach obtains state-of-the-art results on both benchmarks. Code is available at https://github.com/bearpaw/PyraNet.

Electrostatic Self-Assembly of Nanosized Carbon Nitride Nanosheet onto a Zirconium Metal–Organic Framework for Enhanced Photocatalytic CO2 Reduction

Abstract: UiO-66, a zirconium based metal–organic framework, is incorporated with nanosized carbon nitride nanosheets via a facile electrostatic self-assembly method. This hybrid structure exhibits a large surface area and strong CO2 capture ability due to the introduction of UiO-66. We demonstrate that electrons from the photoexcited carbon nitride nanosheet can transfer to UiO-66, which can substantially suppress electron–hole pair recombination in the carbon nitride nanosheet, as well as supply long-lived electrons for the reduction of CO2 molecules that are adsorbed in UiO-66. As a result, the UiO-66/carbon nitride nanosheet heterogeneous photocatalyst exhibits a much higher photocatalytic activity for the CO2 conversion than that of bare carbon nitride nanosheets. We believe this self-assembly method can be extended to other carbon nitride nanosheet loaded materials.

Necklace-like Multishelled Hollow Spinel Oxides with Oxygen Vacancies for Efficient Water Electrolysis.

Abstract: The durability and reactivity of catalysts can be effectively and precisely controlled through the careful design and engineering of their surface structures and morphologies. Herein, we develop a novel “adsorption–calcination–reduction” strategy to synthesize spinel transitional metal oxides with a unique necklace-like multishelled hollow structure exploiting sacrificial templates of carbonaceous microspheres, including NiCo2O4 (NCO), CoMn2O4, and NiMn2O4. Importantly, benefiting from the unique structures and reduction treatment to offer rich oxygen vacancies, the unique reduced NCO (R-NCO) as a bifunctional electrocatalyst exhibits the dual characteristics of good stability as well as high electrocatalytic activity for both the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). At 1.61 V cell voltage, a 10 mA cm–2 water splitting current density is obtained from the dual-electrode, alkaline water electrolyzer. Calculations based on density functional theory (DFT) reveal a mechanism ...