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506 results on '"Qiu, Xiaoqing"'

2. Is the core-cusp problem a matter of perspective: Jeans Anisotropic Modeling against numerical simulations

Author

Wang, Wenting, Zhu, Ling, Li, Zhaozhou, Chen, Yang, Han, Jiaxin, He, Feihong, Yang, Xiaohu, Jing, Yipeng, Frenk, Carlos, Nie, Jialu, Tian, Hao, Liu, Chao, Cao, Yanan, Qiu, Xiaoqing, Helly, John, Grand, Robert J. J., and Gomez, Facundo A.

Subjects
Astrophysics - Astrophysics of Galaxies, Astrophysics - Cosmology and Nongalactic Astrophysics
Abstract

Mock member stars for 28 dwarf galaxies are constructed from the cosmological Auriga simulation, which reflect the dynamical status of realistic stellar tracers. The axis-symmetric Jeans Anisotropic Multi-Gaussian Expansion (JAM) modeling is applied to 6,000 star particles for each system, to recover the underlying matter distribution. The stellar or dark matter component individually is poorly recovered, but the total profile is constrained more reasonably. The mass within the half-mass radius of tracers is recovered the tightest, and the mass between 200 and 300 pc, $M(200-300\mathrm{pc})$, is constrained ensemble unbiasedly, with a scatter of 0.167 dex. If using 2,000 particles and only line-of-sight velocities with typical errors, the scatter in $M(200-300\mathrm{pc})$ is increased by $\sim$50%. Quiescent Sagittarius dSph-like systems and star-forming systems with strong outflows show distinct features, with $M(200-300\mathrm{pc})$ mostly under-estimated for the former, and likely over-estimated for the latter. The biases correlate with the dynamical status, which is a result of contraction motions due to tidal effects in quiescent systems or galactic winds in star-forming systems, driving them out of equilibrium. After including Gaia DR3 proper motion errors, we find proper motions can be as useful as line-of-sight velocities for nearby systems at $<\sim$60 kpc. By extrapolating the actual density profiles and the dynamical constraints down to scales below the resolution, we find the mass within 150 pc can be constrained ensemble unbiasedly, with a scatter of $\sim$0.255 dex. In the end, we show that the contraction of member stars in nearby systems is detectable based on Gaia DR3 proper motion errors., Comment: accepted by ApJ

Published
2022
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29. Identification of Image Operations Based on Steganalytic Features

Author

Li, Haodong, Luo, Weiqi, Qiu, Xiaoqing, and Huang, Jiwu

Subjects
Computer Science - Multimedia
Abstract

Image forensics have attracted wide attention during the past decade. Though many forensic methods have been proposed to identify image forgeries, most of them are targeted ones, since their proposed features are highly dependent on the image operation under investigation. The performance of the well-designed features for detecting the targeted operation usually degrades significantly for other operations. On the other hand, a wise attacker can perform anti-forensics to fool the existing forensic methods, making countering anti-forensics become an urgent need. In this paper, we try to find a universal feature to detect various image processing and anti-forensic operations. Based on our extensive experiments and analysis, we find that any image processing/anti-forensic operations would inevitably modify many image pixels. This would change some inherent statistics within original images, which is similar to the case of steganography. Therefore, we model image processing/anti-forensic operations as steganography problems, and propose a detection strategy by applying steganalytic features. With some advanced steganalytic features, we are able to detect various image operations and further identify their types. In our experiments, we have tested several steganalytic features on 11 different kinds of typical image processing operations and 4 kinds of anti-forensic operations. The experimental results have shown that the proposed strategy significantly outperforms the existing forensic methods in both effectiveness and universality.

Published
2015

40. Quantum-Dot-Derived Catalysts for CO2 Reduction Reaction

Author

Liu, Min, Liu, Mengxia, Wang, Xiaoming, Kozlov, Sergey M., Cao, Zhen, De Luna, Phil, Li, Hongmei, Qiu, Xiaoqing, Liu, Kang, Hu, Junhua, Jia, Chuankun, Wang, Peng, Zhou, Huimin, He, Jun, Zhong, Miao, Lan, Xinzheng, Zhou, Yansong, Wang, Zhiqiang, Li, Jun, Seifitokaldani, Ali, Dinh, Cao Thang, Liang, Hongyan, Zou, Chengqin, Zhang, Daliang, Yang, Yang, Chan, Ting-Shan, Han, Yu, Cavallo, Luigi, Sham, Tsun-Kong, Hwang, Bing-Joe, and Sargent, Edward H.

Published
2019
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42. Three-Dimensional Porous Indium Single-Atom Catalysts with Improved Accessibility for CO2Reduction to Formate

Author

Zhu, Xinwang, Xu, Yan, Ran, Lan, Chen, Shanyong, and Qiu, Xiaoqing

Abstract

Single-atom catalysts (SACs) present substantial potential in electrocatalytic CO2reduction reactions; however, inferior accessibility of single-atom sites to CO2limits the overall CO2RR performances. Herein, we propose to improve the accessibility between In sites and CO2through the construction of a three-dimensional (3D) porous indium single-atom catalyst (In1/NC-3D). The NaCl template-mediated synthesis strategy generates the unique 3D porous nanostructure of In1/NC-3D. Multiple characterizations validate that In1/NC-3D exhibits increased exposure of active sites and enhanced CO2transport/adsorption capacity compared to the bulk In1/NC, thus improving accessibility of active sites to CO2. As a result, the In1/NC-3D presents superior CO2RR performance to the bulk In1/NC, with a partial current density of formate of 67.24 mA cm–2at −1.41 V, relative to a reversible hydrogen electrode (vs RHE). The CO2RR performances with high formate selectivity at a large current density also outperform most reported In-based SACs. Importantly, the In1/NC-3D is demonstrated to maintain an FEformateof >82% at −66.83 mA·cm–2over 21 h. This work highlights the design of a 3D porous single-atom catalyst for efficient CO2RR, promoting the development of advanced catalysts toward advanced energy conversion.

Published
2024
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