University of Science and Technology Beijing

About: University of Science and Technology Beijing is a education organization based out in Beijing, China. It is known for research contribution in the topics: Microstructure & Alloy. The organization has 41558 authors who have published 44473 publications receiving 623229 citations. The organization is also known as: Beijing Steel and Iron Institute.

Investigation on the broadband electromagnetic wave absorption properties and mechanism of Co3O4-nanosheets/reduced-graphene-oxide composite

Abstract: A cobaltosic-oxide-nanosheets/reduced-graphene-oxide composite (CoNSs@RGO) was successfully prepared as a light-weight broadband electromagnetic wave absorber. The effects of the sample thickness and amount of composite added to paraffin samples on the absorption properties were thoroughly investigated. Due to the nanosheet-like structure of Co3O4, the surface-to-volume ratio of the wave absorption material was very high, resulting in a large enhancement in the absorption properties. The maximum refection loss of the CoNSs@RGO composite was–45.15 dB for a thickness of 3.6 mm, and the best absorption bandwidth with a reflection loss below–10 dB was 7.14 GHz with a thickness of 2.9 mm. In addition, the peaks of microwave absorption shifted towards the low frequency region with increasing thickness of the absorbing coatings. The mechanism of electromagnetic wave absorption was attributed to impedance matching of CoNSs@RGO as well as the dielectric relaxation and polarization of RGO. Compared to previously reported absorbing materials, CoNSs@RGO showed better performance as a lightweight and highly efficient absorbing material for application in the high frequency band.

Downlink Energy Efficiency of Power Allocation and Wireless Backhaul Bandwidth Allocation in Heterogeneous Small Cell Networks

Abstract: The widespread application of wireless services and dense devices access has triggered huge energy consumption. Because of the environmental and financial considerations, energy-efficient design in wireless networks has become an inevitable trend. To the best of our knowledge, energy-efficient orthogonal frequency division multiple access (OFDMA) heterogeneous small cell optimization comprehensively considering energy efficiency maximization, power allocation, wireless backhaul bandwidth allocation, and user quality of service is a novel approach and research direction, and it has not been investigated. In this paper, we study the energy-efficient power allocation and wireless backhaul bandwidth allocation in OFDMA heterogeneous small cell networks. Different from the existing resource allocation schemes that maximize the throughput, the studied scheme maximizes energy efficiency by allocating both transmit power of each small cell base station to users and bandwidth for backhauling, according to the channel state information and the circuit power consumption. The problem is first formulated as a non-convex nonlinear programming problem and then it is decomposed into two convex subproblems. A near optimal iterative resource allocation algorithm is designed to solve the resource allocation problem. A suboptimal low-complexity approach is also developed by exploring the inherent structure and property of the energy-efficient design. Simulation results demonstrate the effectiveness of the proposed algorithms by comparing with the existing schemes.

Self-Powered Triboelectric Nanosensor with Poly(tetrafluoroethylene) Nanoparticle Arrays for Dopamine Detection

Abstract: A self-powered triboelectric nanosensor (TENS) based on the contact-separation mode between a thin layer of poly(tetrafluoroethylene) (PTFE) with nanoparticle arrays and an aluminum film was fabricated for the detection of dopamine (DA) in the alkaline condition. High selectivity and sensitivity (detection limit of 0.5 μM, a linear range from 10 μM to 1 mM) have been achieved through the strong interaction between the nonstick PTFE and DA via its oxidative self-polymerization, and the output voltage and current of the developed TENS can reach 116 V and 33 μA, which is exceptionally attractive for the fabrication of self-powered and portable device toward the detection of dopamine.

High-Performance Solar-Blind Deep Ultraviolet Photodetector Based on Individual Single-Crystalline Zn2GeO4Nanowire

Abstract: Solar-blind deep ultraviolet (DUV) photodetectors have been a hot topic in recent years because of their wide commercial and military applications. A wide bandgap (4.68 eV) of ternary oxide Zn2GeO4 makes it an ideal material for the solar-blind DUV detection. Unfortunately, the sensing performance of previously reported photodetectors based on Zn2GeO4 nanowires has been unsatisfactory for practical applications, because they suffer from long response and decay times, low responsivity, and quantum efficiency. Here, high-performance solar-blind DUV photodetectors are developed based on individual single-crystalline Zn2GeO4 nanowires. The transport mechanism is discussed in the frame of the small polaron theory. In situ electrical characterization of individual Zn2GeO4 nanowires reveals a high gain under high energy electron beam. The devices demonstrate outstanding solar-blind light sensing performances: a responsivity of 5.11 × 103 A W−1, external quantum efficiency of 2.45 × 106%, detectivity of ≈2.91 × 1011 Jones, τrise ≈ 10 ms, and τdecay ≈ 13 ms, which are superior to all reported Zn2GeO4 and other ternary oxide nanowire photodetectors. These results render the Zn2GeO4 nanowires particularly valuable for optoelectronic devices.