Northeastern University (China)

About: Northeastern University (China) is a education organization based out in Shenyang, China. It is known for research contribution in the topics: Microstructure & Control theory. The organization has 36087 authors who have published 36125 publications receiving 426807 citations. The organization is also known as: Dōngběi Dàxué & Northeastern University (东北大学).

Light Field Reconstruction Using Convolutional Network on EPI and Extended Applications

Abstract: In this paper, a novel convolutional neural network (CNN)-based framework is developed for light field reconstruction from a sparse set of views. We indicate that the reconstruction can be efficiently modeled as angular restoration on an epipolar plane image (EPI). The main problem in direct reconstruction on the EPI involves an information asymmetry between the spatial and angular dimensions, where the detailed portion in the angular dimensions is damaged by undersampling. Directly upsampling or super-resolving the light field in the angular dimensions causes ghosting effects. To suppress these ghosting effects, we contribute a novel “blur-restoration-deblur” framework. First, the “blur” step is applied to extract the low-frequency components of the light field in the spatial dimensions by convolving each EPI slice with a selected blur kernel. Then, the “restoration” step is implemented by a CNN, which is trained to restore the angular details of the EPI. Finally, we use a non-blind “deblur” operation to recover the spatial high frequencies suppressed by the EPI blur. We evaluate our approach on several datasets, including synthetic scenes, real-world scenes and challenging microscope light field data. We demonstrate the high performance and robustness of the proposed framework compared with state-of-the-art algorithms. We further show extended applications, including depth enhancement and interpolation for unstructured input. More importantly, a novel rendering approach is presented by combining the proposed framework and depth information to handle large disparities.

Gigahertz Dielectric Polarization of Substitutional Single Niobium Atoms in Defective Graphitic Layers.

Abstract: We synthesize two Nb/C composites with an order of magnitude difference in the density of single niobium atoms substituted into defective graphitic layers. The concentration and sites of single Nb atoms are identified using aberration-corrected scanning transmission electron microscopy and density functional theory. Comparing the experimental complex permittivity spectra reveals that a representative dielectric resonance at ∼16 GHz originates from the intrinsic polarization of single Nb atom sites, which is confirmed by theoretical simulations. The single-atom dielectric resonance represents the physical limit of the electromagnetic response of condensed matter, and thus might open up a new avenue for designing electromagnetic wave absorption materials. Single-atom resonance also has important implications in understanding the correlation between the macroscopic dielectric behaviors and the atomic-scale structural origin.

Thermal induced stress and associated cracking in cement-based composite at elevated temperatures––Part I: Thermal cracking around single inclusion

Abstract: This paper presents the development and verification of 2-D mesoscopic thermoelastic damage model used to numerically quantify the thermal stresses and crack development of a cement-based composite subjected to elevated temperatures. The program is then used to study the thermal fracture behavior of a cement-based matrix with a single inclusion. The results show that the mechanisms of thermal damage and fracture of the composite depend on (i) the difference between the coefficients of thermal expansion (CTE) of the inclusion and the cement-based matrix, (ii) the strengths of materials, and (iii) the heterogeneity of materials at meso-scale. The thermal cracking is an evolution process from diffused damage, nucleation, and finally linkage of cracks. If the CTE of the inclusion is greater than that of the matrix, radial cracks will form in the matrix. On the other hand, inclusion cracks and tangential cracks at the interface between inclusion and matrix will form if the CTE of the inclusion is smaller than that of the matrix.