Harbin Institute of Technology

About: Harbin Institute of Technology is a education organization based out in Harbin, China. It is known for research contribution in the topics: Microstructure & Control theory. The organization has 88259 authors who have published 109297 publications receiving 1603393 citations. The organization is also known as: HIT.

Morphology-Controlled Synthesis and Electromagnetic Properties of Porous Fe3O4 Nanostructures from Iron Alkoxide Precursors

Abstract: Well-defined porous Fe3O4 flower-like nanostructures have been synthesized by decomposition of the iron alkoxide precursors that are prepared by heating up the solution of FeCl3·6H2O, urea, and surfactant in ethylene glycol. Time-dependent SEM studies indicate that the structure evolution of iron alkoxide precursors contains a fast nucleation of primary nanoparticles followed by a subsequent growth. By varying the amount of surfactant in the solution, the morphology and microstructure of the iron alkoxide precursors can be controlled. After calcination, the flower-like nanostructures of the precursors are maintained in the final products Fe3O4, with each petal of the flower being transformed from a dense structure with a smooth surface into a highly porous structure consisting of interconnected nanoparticles due to the removal of organic species in the iron alkoxide by pyrolysis. Compared to traditional ferrites and ferromagnetic alloys, the complex permittivity of the flower-like porous Fe3O4 samples is ...

Pea-like Fe/Fe3C Nanoparticles Embedded in Nitrogen-Doped Carbon Nanotubes with Tunable Dielectric/Magnetic Loss and Efficient Electromagnetic Absorption

Abstract: One-dimensional microstructure has been regarded as one of the most desirable configurations for magnetic carbon-based microwave absorbing materials (MAMs). Herein, pea-like Fe/Fe3C nanoparticles embedded in nitrogen-doped carbon nanotubes (Fe/Fe3C@NCNTs) are successfully prepared through a direct pyrolysis of the mixture of FeCl3·6H2O and melamine under inert atmosphere. The chemical composition and microstructural feature of these Fe/Fe3C@NCNTs composites are highly dependent on the pyrolysis temperature. As a result, their electromagnetic properties can be also manipulated, where dielectric loss gradually decreases with the increasing pyrolysis temperature and magnetic loss presents a reverse variation trend. When the pyrolysis temperature reaches 600 °C, the as-obtained composite, Fe/Fe3C@NCNTs-600 can perform a maximum reflection loss of −46.0 dB at 3.6 GHz with a thickness of 4.97 mm and a qualified bandwidth of 14.8 GHz with the integrated thickness from 1.00 to 5.00 mm. It is very interesting that...

Cooperative Control of Distributed Energy Storage Systems in a Microgrid

Abstract: Energy storage systems (ESSs) are often proposed to support the frequency control in microgrid systems. Due to the intermittency of the renewable generation and constantly changing load demand, the charging/discharging of various ESSs in an autonomous microgrid needs to be properly coordinated to ensure the supply-demand balance. Recent research has discovered that the charging/discharging efficiency of ESSs has remarkable dependence on the charging/discharging rate and state-of-charge of the ESS. This paper proposes a distributed cooperative control strategy for coordinating the ESSs to maintain the supply-demand balance and minimize the total power loss associated with charging/discharging inefficiency. The effectiveness of the proposed approach is validated by simulation results.