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763 results on '"Wang, Baowei"'

52. Hausdorff dimension of the set approximated by irrational rotations

Author

Kim, Dong Han, Rams, Michał, and Wang, Baowei

Subjects
Mathematics - Number Theory, Mathematics - Dynamical Systems, 11K55, 11J71, 28A80
Abstract

Let $\theta$ be an irrational number and $\varphi: {\mathbb N} \to {\mathbb R}^{+}$ be a monotone decreasing function tending to zero. Let $$E_\varphi(\theta) =\Big\{y \in \mathbb R: \|n\theta- y\|<\varphi(n), \ {\text{for infinitely many}}\ n\in {\mathbb N} \Big\}, $$ i.e. the set of points which are approximated by the irrational rotation with respect to the error function $\varphi(n)$. In this article, we give a complete description of the Hausdorff dimension of $E_\varphi(\theta)$ for any monotone function $\varphi$ and any irrational $\theta$., Comment: 15pages

Published
2016
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57. Enabling Electron Delocalization by Conductor Heterostructure for Highly Reversible Sodium Storage.

Author

Liu, Chang, Wang, Baowei, Song, Zirui, Xiao, Xuhuan, Cao, Ziwei, Xiong, Dengyi, Deng, Wentao, Hou, Hongshuai, Yang, Yingchang, Zou, Guoqiang, and Ji, Xiaobo

Subjects
*ELECTRON delocalization, *SODIUM ions, *NIOBIUM oxide, *ELECTRIC conductivity, *DENSITY functional theory, *SODIUM
Abstract

Niobium oxides have fascinated numerous interests for ultrafast sodium‐ion batteries due to their impressive stability, fast pseudocapacitive kinetics, and high safety features. However, the poor intrinsic electronic conductivity and unrevealed mechanisms largely limit their further applications. Here, inspired by density functional theory (DFT) calculations, the introduction of conductor heterostructure (Nb2O5/NbSe2) can largely decrease the bulk phase inserted energy of Na+ from 9.88 to −3.54 eV, as well as promote the delocalization of electron, greatly improving the electrical conductivity of Nb2O5. As expected, the as‐obtained orthorhombic niobium pentoxide (T‐Nb2O5‐x‐NbSe2@C) delivers a high conductivity of 3.69 S cm−1, exhibiting a great improvement of four orders magnitude than that of the parent Nb2O5 (1.87 × 10−4 S cm−1). Impressively, T‐Nb2O5‐x‐NbSe2@C possesses a high reversible capacity of 249 mAh g−1 at 0.1 A g−1, as well as excellent rate performance of 63 mAh g−1 at 5.0 A g−1, nearly twins the capacity of parent porous Nb2O5. Furthermore, the periodic evolutions of the main peaks for targeted electrodes during repeated charging/discharging processes have been further revealed by in situ XRD, demonstrating a highly reversible inserted/extracted storage mechanism of Na+. This work provides a novel method to improve the conductivity of materials by constructing conductor heterojunction. [ABSTRACT FROM AUTHOR]

Published
2024
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66. Quantitative recurrence properties in conformal iterated function systems

Author

Seuret, Stéphane and Wang, Baowei

Subjects
Mathematics - Dynamical Systems, 37F35, 37D35, 28A80
Abstract

Let $\Lambda$ be a countable index set and $S=\{\phi_i: i\in \Lambda\}$ be a conformal iterated function system on $[0,1]^d$ satisfying the open set condition. Denote by $J$ the attractor of $S$. With each sequence $(w_1,w_2,...)\in \Lambda^{\mathbb{N}}$ is associated a unique point $x\in [0,1]^d$. Let $J^\ast$ denote the set of points of $J$ with unique coding, and define the mapping $T:J^\ast \to J^\ast$ by $Tx= T (w_1,w_2, w_3...) = (w_2,w_3,...)$. In this paper, we consider the quantitative recurrence properties related to the dynamical system $(J^\ast, T)$. More precisely, let $f:[0,1]^d\to \mathbb{R}^+$ be a positive function and $$R(f):=\{x\in J^\ast: |T^nx-x|

Published
2013

71. Diophantine approximation of the orbit of 1 in the dynamical system of bete expansions

Author

Li, Bing, Persson, Tomas, Wang, Baowei, and Wu, Jun

Subjects
Mathematics - Dynamical Systems, 11K55, 28A80
Abstract

We consider the distribution of the orbits of the number 1 under the $\beta$-transformations $T_\beta$ as $\beta$ varies. Mainly, the size of the set of $\beta>1$ for which a given point can be well approximated by the orbit of 1 is measured by its Hausdorff dimension. That is, the dimension of the following set $$ E\big({\ell_n}_{n\ge 1}, x_0\big)=\Big{\beta>1: |T^n_{\beta}1-x_0|<\beta^{-\ell_n}, {for infinitely many} n\in \N\Big} $$ is determined, where $x_0$ is a given point in $[0,1]$ and ${\ell_n}_{n\ge 1}$ is a sequence of integers tending to infinity as $n\to \infty$. For the proof of this result, the notion of the recurrence time of a word in symbolic space is introduced to characterize the lengths and the distribution of cylinders (the set of $\beta$ with a common prefix in the expansion of 1) in the parameter space ${\beta\in \R: \beta>1}$.

Published
2013

74. A VANET Anonymous Authentication Mechanism for Multi-level Application Scenarios

Author

Wang, Xiaoliang, Jiang, Jianming, Wang, Baowei, Xia, Zhihua, Hutchison, David, Series Editor, Kanade, Takeo, Series Editor, Kittler, Josef, Series Editor, Kleinberg, Jon M., Series Editor, Mattern, Friedemann, Series Editor, Mitchell, John C., Series Editor, Naor, Moni, Series Editor, Pandu Rangan, C., Series Editor, Steffen, Bernhard, Series Editor, Terzopoulos, Demetri, Series Editor, Tygar, Doug, Series Editor, Weikum, Gerhard, Series Editor, Sun, Xingming, editor, Pan, Zhaoqing, editor, and Bertino, Elisa, editor

Published
2018
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80. Robust Cross‐Linked Na3V2(PO4)2F3 Full Sodium‐Ion Batteries.

Author

Gao, Jinqiang, Tian, Ye, Ni, Lianshan, Wang, Baowei, Zou, Kangyu, Yang, Yingchang, Wang, Ying, Banks, Craig E., Zhang, Dou, Zhou, Kechao, Liu, Huan, Deng, Wentao, Zou, Guoqiang, Hou, Hongshuai, and Ji, Xiaobo

Subjects
CHARGE transfer kinetics, ENERGY storage, SODIUM ions, DIFFUSION kinetics, ENERGY density
Abstract

Sodium‐ion batteries (SIBs) have rapidly risen to the forefront of energy storage systems as a promising supplementary for Lithium‐ion batteries (LIBs). Na3V2(PO4)2F3 (NVPF) as a common cathode of SIBs, features the merits of high operating voltage, small volume change and favorable specific energy density. However, it suffers from poor cycling stability and rate performance induced by its low intrinsic conductivity. Herein, we propose an ingenious strategy targeting superior SIBs through cross‐linked NVPF with multi‐dimensional nanocarbon frameworks composed of amorphous carbon and carbon nanotubes (NVPF@C@CNTs). This rational design ensures favorable particle size for shortened sodium ion transmission pathway as well as improved electronic transfer network, thus leading to enhanced charge transfer kinetics and superior cycling stability. Benefited from this unique structure, significantly improved electrochemical properties are obtained, including high specific capacity (126.9 mAh g−1 at 1 C, 1 C = 128 mA g−1) and remarkably improved long‐term cycling stability with 93.9% capacity retention after 1000 cycles at 20 C. The energy density of 286.8 Wh kg−1 can be reached for full cells with hard carbon as anode (NVPF@C@CNTs//HC). Additionally, the electrochemical performance of the full cell at high temperature is also investigated (95.3 mAh g−1 after 100 cycles at 1 C at 50 °C). Such nanoscale dual‐carbon networks engineering and thorough discussion of ion diffusion kinetics might make contributions to accelerating the process of phosphate cathodes in SIBs for large‐scale energy storages. [ABSTRACT FROM AUTHOR]

Published
2024
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90. Temperature Error Correction Based on BP Neural Network in Meteorological Wireless Sensor Network

Author

Wang, Baowei, Gu, Xiaodu, Ma, Li, Yan, Shuangshuang, Hutchison, David, Series editor, Kanade, Takeo, Series editor, Kittler, Josef, Series editor, Kleinberg, Jon M., Series editor, Mattern, Friedemann, Series editor, Mitchell, John C., Series editor, Naor, Moni, Series editor, Pandu Rangan, C., Series editor, Steffen, Bernhard, Series editor, Terzopoulos, Demetri, Series editor, Tygar, Doug, Series editor, Weikum, Gerhard, Series editor, Sun, Xingming, editor, Liu, Alex, editor, Chao, Han-Chieh, editor, and Bertino, Elisa, editor

Published
2016
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98. An Extreme Learning Approach to Fast Prediction in the Reduce Phase of a Cloud Platform

Author

Liu, Qi, Cai, Weidong, Shen, Jian, Wang, Baowei, Fu, Zhangjie, Linge, Nigel, Hutchison, David, Series editor, Kanade, Takeo, Series editor, Kittler, Josef, Series editor, Kleinberg, Jon M., Series editor, Mattern, Friedemann, Series editor, Mitchell, John C., Series editor, Naor, Moni, Series editor, Pandu Rangan, C., Series editor, Steffen, Bernhard, Series editor, Terzopoulos, Demetri, Series editor, Tygar, Doug, Series editor, Weikum, Gerhard, Series editor, Huang, Zhiqiu, editor, Sun, Xingming, editor, Luo, Junzhou, editor, and Wang, Jian, editor

Published
2015
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