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.

Hierarchical nanosheet-based CoMoO4–NiMoO4 nanotubes for applications in asymmetric supercapacitors and the oxygen evolution reaction

Abstract: Hollow structures with hierarchical architecture and multi-composition have attracted extensive interest because of their fascinating physicochemical properties as well as wide applications. Herein we report the designed synthesis of hierarchical nanosheet-based CoMoO4–NiMoO4 nanotubes by a hydrothermal treatment and a subsequent calcination method. The walls of the hierarchical nanotubes are composed of interconnected NiMoO4 nanosheets and CoMoO4 nanoparticles anchored on the surface of the nanosheets. The diameter of the hollow interior, the thickness of NiMoO4 nanosheets and the diameter of CoMoO4 nanoparticles are around 180 nm, less than 6 nm and 3 nm, respectively, providing the hierarchical nanotubes with a high surface area and a large pore volume. When evaluated as electrodes for pseudocapacitors, the hierarchical nanotubes with an appropriate amount of CoMoO4 show a high specific capacitance of 1079 F g−1 at a current density of 5 A g−1 and excellent stability with 98.4% capacitance retention after 1000 cycles. Furthermore, an asymmetric capacitor, consisting of active carbon and hierarchical nanosheet-based CoMoO4–NiMoO4 nanotubes as negative and positive electrodes, respectively, delivers an energy density of 33 W h kg−1 at a power density of 375 W kg−1, and 16.3 W h kg−1 even at a high power density of 6000 W kg−1. The supercapacitive properties are much higher than those of single-phase NiMoO4 nanotubes, and most of the other metal molybdates and metal oxides reported previously. Besides, the hierarchical nanotubes also exhibit much better electrocatalytic activity for the oxygen evolution reaction than single-phase NiMoO4 nanotubes, and most of the other metal molybdates and metal oxides. Our results demonstrate the importance of rational design of complex hollow structures with enhanced properties for a wide range of practical applications.

Energy-Efficient Distributed Filtering in Sensor Networks: A Unified Switched System Approach

Abstract: This paper is concerned with the energy-efficient distributed filtering in sensor networks, and a unified switched system approach is proposed to achieve this goal. For the system under study, the measurement is first sampled under nonuniform sampling periods, then the local measurement elements are selected and quantized for transmission. Then, the transmission rate is further reduced to save constrained power in sensors. Based on the switched system approach, a unified model is presented to capture the nonuniform sampling, the measurement size reduction, the transmission rate reduction, the signal quantization, and the measurement missing phenomena. Sufficient conditions are obtained such that the filtering error system is exponentially stable in the mean-square sense with a prescribed $ {H}_{ {\infty }}$ performance level. Both simulation and experiment studies are given to show the effectiveness of the proposed new design technique.