University of Electronic Science and Technology of China

About: University of Electronic Science and Technology of China is a education organization based out in Chengdu, China. It is known for research contribution in the topics: Antenna (radio) & Dielectric. The organization has 50594 authors who have published 58502 publications receiving 711188 citations. The organization is also known as: UESTC.

Intelligent Reflecting Surface-Assisted Cognitive Radio System

Abstract: Cognitive radio (CR) is an effective solution to improve the spectral efficiency (SE) of wireless communications by allowing the secondary users (SUs) to share spectrum with primary users (PUs). Meanwhile, intelligent reflecting surface (IRS), also known as reconfigurable intelligent surface (RIS), has been recently proposed as a promising approach to enhance energy efficiency (EE) of wireless communication systems through intelligently reconfiguring the channel environment. To improve both SE and EE, in this paper, we introduce multiple IRSs to a downlink multiple-input single-output (MISO) CR system, in which a single SU coexists with a primary network with multiple PU receivers (PU-RXs). Our design objective is to maximize the achievable rate of SU subject to a total transmit power constraint on the SU transmitter (SU-TX) and interference temperature constraints on the PU-RXs, by jointly optimizing the beamforming at SU-TX and the reflecting coefficients at each IRS. Both perfect and imperfect channel state information (CSI) cases are considered in the optimization. Numerical results demonstrate that IRS can significantly improve the achievable rate of SU under both perfect and imperfect CSI cases.

Influence of polymerization temperature on NH3 response of PANI/TiO2 thin film gas sensor

Abstract: Polyaniline/titanium dioxide (PANI/TiO 2 ) nanocomposite thin films were processed on a silicon substrate with gold interdigital electrodes by an in-situ self-assembly approach for NH 3 gas-sensing application, and the effect of polymerization temperature on the gas response of the PANI/TiO 2 thin film gas sensor was investigated. The results showed that the PANI/TiO 2 thin film prepared at 10 °C was superior to those prepared at other temperatures in terms of response properties, which also exhibited good reproducibility, selectivity and long-term stability. UV–vis absorption and surface morphology characterization of the nanocomposite thin films were performed to explain these different gas-sensing properties. The sensing mechanism was also discussed.

An ultrafine platinum–cobalt alloy decorated cobalt nanowire array with superb activity toward alkaline hydrogen evolution

Abstract: It is highly desired to design and develop highly efficient electrocatalysts for alkaline hydrogen evolution reactions. Herein, we report the development of ultrafine PtCo alloy nanoparticle decorated one-dimensional Co nanowires grown on Ti mesh (PtCo–Co/TiM). Owing to its favorable composition and structure, the PtCo–Co/TiM can deliver an ultrahigh current density of 46.5 mA cm−2 at an overpotential of 70 mV in 1.0 M KOH, superior to recently reported Pt-based electrocatalysts. This catalyst also provides excellent long-term electrochemical durability with its catalytic activity being maintained for at least 50 h.

MISC Array: A New Sparse Array Design Achieving Increased Degrees of Freedom and Reduced Mutual Coupling Effect

Abstract: Recently, nested and coprime arrays have attracted considerable interest due to their capability of providing increased array aperture, enhanced degrees of freedom (DOFs), and reduced mutual coupling effect compared to uniform linear arrays (ULAs). These features are critical to improving the performance of direction-of-arrival estimation and adaptive beamforming. In this paper, a new sparse array configuration based on the maximum inter-element spacing constraint (MISC) is proposed. The MISC array configuration generally consists of three sparse ULAs plus two separate sensors that are appropriately placed. The MISC array configurations are designed based on the inter-element spacing set, which, for a given number of sensors, is uniquely determined by a closed-form expression. We also derive closed-form expressions for the number of uniform DOFs of the MISC arrays with any number of sensors. Compared with the existing sparse arrays, the MISC array enjoys two important advantages, namely, providing a higher number of DOFs and reducing the mutual coupling effects. Numerical simulations are conducted to verify the superiority of the MISC array over other sparse arrays.