National University of Defense Technology

About: National University of Defense Technology is a education organization based out in Changsha, China. It is known for research contribution in the topics: Radar & Synthetic aperture radar. The organization has 39430 authors who have published 40181 publications receiving 358979 citations. The organization is also known as: Guófáng Kēxuéjìshù Dàxué & NUDT.

Quasi-one-dimensional phononic crystals studied using the improved lumped-mass method : Application to locally resonant beams with flexural wave band gap

Abstract: By replacing the rectangle cells with arbitrary triangle ones, an improved lumped-mass method is introduced to study the propagation of flexural elastic waves in the infinite quasi-one-dimensional beams with locally resonant structures. Low frequency band gap is predicted and studied. The transmission frequency response function of a finite sample composed of duralumin beam and oscillators is calculated with the finite element method. Vibration experiments are conducted to verify the theoretical results, and all the results match well. The existence of locally resonant band gaps in the flexural waves of beams provides a way for the design of low-frequency vibration insulations.

Feasibility of chitosan-alginate (Chi-Alg) hydrogel used as scaffold for neural tissue engineering: a pilot study in vitro

Abstract: In tissue engineering, scaffolding plays an important role in accommodating and stimulating new tissue growth Chitosan and alginate are two widely used natural polymers in tissue engineering Here, we prepared the chitosan-alginate (Chi-Alg) hydrogel from naturally derived chitosan and alginate polymers The Fourier-transformed infrared spectroscopy and X-ray diffraction results demonstrated that a chitosan-alginate hydrogel was constructed due to the strong ionic interaction between the positively charged amino groups of chitosan and the negatively charged carboxyl groups of alginate The scanning electron microscopy and contact angle results showed the inner porous structure and highly hydrophilic property of chitosan-alginate hydrogel As the two most promising cell types in nerve tissue engineering, both olfactory ensheathing cells and neural stem cells proliferated well on the chitosan-alginate hydrogel All results indicated the good potential application of a chitosan-alginate hydrogel for

Carrier Modulation of Ambipolar Few‐Layer MoTe2 Transistors by MgO Surface Charge Transfer Doping

Abstract: Semiconducting molybdenum ditelluride (2H-MoTe2), a fast-emerging 2D material with an appropriate band gap and decent carrier mobility, is configured as field-effect transistors and is the focus of substantial research interest, showing hole-dominated ambipolar characteristics. Here, carrier modulation of ambipolar few-layer MoTe2 transistors is demonstrated utilizing magnesium oxide (MgO) surface charge transfer doping. By carefully adjusting the thickness of MgO film and the number of MoTe2 layers, the carrier polarity of MoTe2 transistors from p-type to n-type can be reversely controlled. The electron mobility of MoTe2 is significantly enhanced from 0.1 to 20 cm2 V−1 s−1 after 37 nm MgO film doping, indicating a greatly improved electron transport. The effective carrier modulation enables to achieve high-performance complementary inverters with high DC gain of >25 and photodetectors based on few-layer MoTe2 flakes. The results present an important advance toward the realization of electronic and optoelectronic devices based on 2D transition-metal dichalcogenide semiconductors.

Bipolar loop-like non-volatile strain in the (001)-oriented Pb(Mg1/3Nb2/3)O3-PbTiO3 single crystals.

Abstract: Strain has been widely used to manipulate the properties of various kinds of materials, such as ferroelectrics, semiconductors, superconductors, magnetic materials, and “strain engineering” has become a very active field. For strain-based information storage, the non-volatile strain is very useful and highly desired. However, in most cases, the strain induced by converse piezoelectric effect is volatile. In this work, we report a non-volatile strain in the (001)-oriented Pb(Mg1/3Nb2/3)O3-PbTiO3 single crystals and demonstrate an approach to measure the non-volatile strain. A bipolar loop-like S-E curve is revealed and a mechanism involving 109° ferroelastic domain switching is proposed. The non-volatile high and low strain states should be significant for applications in information storage.

Joint Neural Collaborative Filtering for Recommender Systems

Abstract: We propose a Joint Neural Collaborative Filtering (J-NCF) method for recommender systems. The J-NCF model applies a joint neural network that couples deep feature learning and deep interaction modeling with a rating matrix. Deep feature learning extracts feature representations of users and items with a deep learning architecture based on a user-item rating matrix. Deep interaction modeling captures non-linear user-item interactions with a deep neural network using the feature representations generated by the deep feature learning process as input. J-NCF enables the deep feature learning and deep interaction modeling processes to optimize each other through joint training, which leads to improved recommendation performance. In addition, we design a new loss function for optimization that takes both implicit and explicit feedback, point-wise and pair-wise loss into account. Experiments on several real-world datasets show significant improvements of J-NCF over state-of-the-art methods, with improvements of up to 8.24% on the MovieLens 100K dataset, 10.81% on the MovieLens 1M dataset, and 10.21% on the Amazon Movies dataset in terms of HR@10. NDCG@10 improvements are 12.42%, 14.24%, and 15.06%, respectively. We also conduct experiments to evaluate the scalability and sensitivity of J-NCF. Our experiments show that the J-NCF model has a competitive recommendation performance with inactive users and different degrees of data sparsity when compared to state-of-the-art baselines.