Harbin Engineering University

About: Harbin Engineering University is a education organization based out in Harbin, Heilongjiang, China. It is known for research contribution in the topics: Control theory & Microstructure. The organization has 31149 authors who have published 27940 publications receiving 276787 citations. The organization is also known as: HEU.

Optimizing the charge transfer process by designing Co3O4@PPy@MnO2 ternary core–shell composite

Abstract: In this paper, the incorporation of a highly conductive material (polypyrrole) into a binary metal-oxide core–shell structured composite is adopted to optimize the charge transfer process to further improve electrochemical performance. Because of enhanced electron transfer capability, charge transfer resistances of the ternary core–shell structured composites are reduced and the electrochemical performances are improved. For example, the Co3O4@PPy@MnO2 ternary core–shell heterostructured composite exhibits high specific capacitance and excellent rate capability (53% of capacity retention rate at 40 A g−1 compared with 782 F g−1 at 0.5 A g−1). The composite shows good cycling stability with 97.6% capacity retention over 2000 cycles at 5 A g−1. These results demonstrate the potential of core–shell composites to further improve the performance in supercapacitor electrodes.

A unified method for free vibration analysis of circular, annular and sector plates with arbitrary boundary conditions:

Abstract: The vibrations of circular, annular, and sector plates are traditionally considered as different boundary value problems and often treated using different solution algorithms and procedures. This p...

Free vibration of refined higher-order shear deformation composite laminated beams with general boundary conditions

Abstract: In this paper, a unified formulation which is based on a general refined shear deformation beam theory is presented to conduct free vibration analysis of composite laminated beams subjected to general boundary conditions. In the refined theory model, the displacement fields are chosen by including the high-order variation of transverse shear strain through the thickness of the beam and meeting the stress-free boundary conditions on both the top and bottom surfaces. With considering the material couplings and the Poisson's effect, the governing equations and appropriate boundary conditions are derived from the Hamilton's principle. Exact solutions are obtained by employing the method of reverberation ray matrix (MRRM). In order to implement general boundary conditions, the artificial spring boundary technique is introduced in the MRRM to make it suitable for different boundary cases. The present solutions are compared with those available in the literature to confirm their validity. A systematic parameter study for composite beams with various boundary conditions, fiber orientations, lamina numbers and orthotropic ratios is also performed. New results for free vibration involving composite laminated beams with various boundary constraints are also presented for the first time and they may be served as benchmark for researchers in this field.

Enhancing the Li Storage Capacity and Initial Coulombic Efficiency for Porous Carbons by Sulfur Doping

Abstract: Here, we report a new approach to synthesizing S-doped porous carbons and achieving both a high capacity and a high Coulombic efficiency in the first cycle for carbon nanostructures as anodes for Li ion batteries. S-doped porous carbons (S-PCs) were synthesized by carbonization of pitch using magnesium sulfate whiskers as both templates and S source, and a S doping up to 10.1 atom % (corresponding to 22.5 wt %) was obtained via a S doping reaction. Removal of functional groups or highly active C atoms during the S doping has led to formation of much thinner solid-electrolyte interface layer and hence significantly enhanced the Coulombic efficiency in the first cycle from 39.6% (for the undoped porous carbon) to 81.0%. The Li storage capacity of the S-PCs is up to 1781 mA h g–1 at the current density of 50 mA g–1, more than doubling that of the undoped porous carbon. Due to the enhanced conductivity, the hierarchically porous structure and the excellent stability, the S-PC anodes exhibit excellent rate cap...