arXiv subjects

Ailing Chen

Publications and source records attributed to Ailing Chen.

3 recordsLinked to original sources

arXiv2022

Softened sp2-sp3 bonding network leads to strong anharmonicity and weak hydrodynamics in graphene+

Graphene+, a novel carbon monolayer with sp2-sp3 hybridization, is recently reported to exhibit graphene-like Dirac properties and unprecedented out-of-plane half-auxetic behavior [Yu et al, Cell Reports Physical Science, 3 100790 (2022)]. Herein, from comprehensively state-of-the-art first-principles studies, we report the exceptional lattice thermal transport properties of graphene+ driven by the unique sp2-sp3 crystal configuration. At room temperature, the thermal conductivity of graphene+ is calculated to be ~170 W/mK, which is much lower than that of graphene (~3170 W/mK) Despite the buckling structure, weak phonon scattering phase space is trapped in graphene+. Thus, the reduction in thermal conductivity magnitude stems from soft bonding due to the unique sp2-sp3 crystal configuration. Soft bonding suppresses the vibrations of acoustic phonons, which leads to strong anharmonicity and weak phonon hydrodynamics. Further, lower group velocity, relaxation time and smaller phonon mean free path emerge in graphene+, and the significantly decreased thermal conductivity is achieved. Our study provides fundamental physical insights into the thermal transport properties of graphene+, and it serves as an ideal model to study atomic bonding versus thermal transport properties due to weak scattering phase space.

cond-mat.mtrl-sci↗

arXiv2022

Joint user association and power allocation in ultra-dense mmWave networks: a multi-connectivity approach

In ultra-dense millimeter wave (mmWave) networks, mmWave signals suffer from severe path losses and are easily blocked by obstacles. Meanwhile, ultra-dense deployment causes excessive handovers, which reduces the data link reliability. To alleviate the above issues, the novel technology, known as multi-connectivity enabled user association (MCUA) is incorporated in this letter. We aim to jointly optimize MCUAs and downlink (DL) power allocations (PAs) to maximize the DL rate of each user simultaneously, rather than total. This is a non-convex nonlinear 0-1 mixed integer multi-objective optimization problem and quite complicated. To solve it, we first use the weighted sum method to scalarize it as a single-objective optimization problem (SOOP), and then relax the binary association variables to real ones. Considering that the relaxed SOOP is still non-convex, we perform a series of transformations upon it and make it a differential of convex programming. Finally, we develop an iterative algorithm based on the convex-concave procedure to solve the SOOP. Numerical results are presented to demonstrate the effectiveness of the proposed algorithms.

cs.NI↗

arXiv2022

The record low thermal conductivity of monolayer Cuprous Iodide (CuI) with direct wide bandgap

Two-dimensional materials have attracted lots of research interests due to the fantastic properties that are unique to the bulk counterparts. In this paper, from the state-of-the-art first-principles, we predicted the stable structure of monolayer counterpart of the {\gamma}-CuI (Cuprous Iodide), which is a p-type wide bandgap semiconductor. The monolayer CuI presents multifunctional superiority in terms of electronic, optical, and thermal transport properties. Specifically, the ultralow thermal conductivity of 0.116 Wm-1K-1 is predicted for monolayer CuI, which is much lower than {\gamma}-CuI (0.997 Wm-1K-1) and other typical semiconductors. Moreover, an ultrawide direct bandgap of 3.57 eV is found in monolayer CuI, which is larger than {\gamma}-CuI (2.95-3.1 eV), promoting the applications in nano-/optoelectronics with better optical performance. The ultralow thermal conductivity and direct wide bandgap of monolayer CuI as reported in this study would promise its potential applications in transparent and wearable electronics.

cond-mat.mtrl-sci↗