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2,381 results on '"Zhang, Yajie"'

51. Active stability of the shield tunneling face crossing an adjacent existing tunnel: transparent clay model test and DEM simulation

Author

Lei, Huayang, Liu, Yingnan, Hu, Yao, Jia, Rui, and Zhang, Yajie

Subjects
Tunnels -- Mechanical properties, Structural dynamics -- Analysis, Structural stability -- Analysis, Earth sciences
Abstract

Tunnel face stability is critical for tunneling safety, especially in constructing a tunnel adjacent to another. In tunnel construction, if there is an adjacent existing tunnel and the active failure of the tunnel face happens, there will be severe consequences. Therefore, the active stability of shield tunnel face should be studied considering existing tunnels nearby. In this work, a series of transparent clay model tests were conducted to investigate the active stability of a shield tunnel face adjacent to an existing tunnel based on the development process, failure mode, influence range and support force. In addition, discrete element method was used to study the shield tunnel face stability under various conditions. The role of existing tunnels on the shield tunnel face stability was discussed. The failure mode of the shield tunnel face is an overall failure mode and similar to a wedge shape and ladder shape along the longitudinal and transverse section, respectively. The critical support force ratio is approximately 4.5%. The relative vertical and horizontal distance have significant influences on failure mode, while the influence of burial depth and overlapping angles are not significant. Key words: active stability, tunnel face, transparent clay model test, numerical simulation, existing tunnel, 1. Introduction 1.1. Background With the arrival of the climax of the metro construction in China, the urban rail transit system has developed from a single line to a complex [...]

Published
2023
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52. EMC System Control on XX-2 Satellite

Author

Zhou, Liping, Zhang, Hua, Cheng, Lili, Zhang, Yajie, Angrisani, Leopoldo, Series Editor, Arteaga, Marco, Series Editor, Panigrahi, Bijaya Ketan, Series Editor, Chakraborty, Samarjit, Series Editor, Chen, Jiming, Series Editor, Chen, Shanben, Series Editor, Chen, Tan Kay, Series Editor, Dillmann, Rüdiger, Series Editor, Duan, Haibin, Series Editor, Ferrari, Gianluigi, Series Editor, Ferre, Manuel, Series Editor, Hirche, Sandra, Series Editor, Jabbari, Faryar, Series Editor, Jia, Limin, Series Editor, Kacprzyk, Janusz, Series Editor, Khamis, Alaa, Series Editor, Kroeger, Torsten, Series Editor, Li, Yong, Series Editor, Liang, Qilian, Series Editor, Martín, Ferran, Series Editor, Ming, Tan Cher, Series Editor, Minker, Wolfgang, Series Editor, Misra, Pradeep, Series Editor, Möller, Sebastian, Series Editor, Mukhopadhyay, Subhas, Series Editor, Ning, Cun-Zheng, Series Editor, Nishida, Toyoaki, Series Editor, Oneto, Luca, Series Editor, Pascucci, Federica, Series Editor, Qin, Yong, Series Editor, Seng, Gan Woon, Series Editor, Speidel, Joachim, Series Editor, Veiga, Germano, Series Editor, Wu, Haitao, Series Editor, Zamboni, Walter, Series Editor, Zhang, Junjie James, Series Editor, Sun, Jiande, editor, Wang, Yue, editor, Huo, Mengyao, editor, and Xu, Lexi, editor

Published
2023
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53. Synergetic effect of temperature and PM2.5 on mortality of cardiovascular and cerebrovascular diseases

Author

YANG Sixu, PENG Li, YE Xiaofang, YANG Dandan, ZHANG Yajie, and ZHOU Yi

Subjects
temperature, pm2.5, cardiovascular and cerebrovascular disease, synergetic effect, Medicine
Abstract

ObjectiveTo explore the synergetic effect of temperature and PM2.5 on cardiovascular and cerebrovascular diseases.MethodWe collected cardiovascular and cerebrovascular death cases，air pollution and meteorological data during the same period in Pudong New Area from 2013 to 2018.We used generalized additive models （GAMs） with poisson regression including non-stratification model， nonparametric bivariate response model and pollution-stratified parametric model， to assess the interaction between temperature and PM2.5 and on the number of cardiovascular cerebrovascular and cerebrovascular disease deaths.ResultsThe exposure-response relationship between temperature and the number of cardiovascular and cerebrovascular deaths exhibited "U" type and the most comfortable temperature was 18.9 ℃. When the concentrations of PM2.5 increased by 10 μg·m-3， the deaths of total， male， female， ≤75 years and >75 years increased， respectively， by 0.60%（95%CI： 0.30%‒0.91%）， 0.77%（95%CI：0.34%‒1.20%）， 0.46%（95%CI：0.05%‒0.86%）， 0.66%（95%CI：0.03%‒1.30%） and 0.59%（95%CI：0.26%‒0.92%）. With the increase of PM2.5 concentration level， the impact of temperature on cardiovascular and cerebrovascular diseases gradually increased， and the impact was the most significant when the concentration of PM2.5 was more than 150 µg·m-3. There were different sensitive people in different seasons.ConclusionPM2.5 concentration levels of mild pollution and above can exacerbate the negative effects of temperature on cardiovascular and cerebrovascular diseases.

Published
2023
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67. A Second-Order Nonlocal Approximation for Manifold Poisson Model with Dirichlet Boundary

Author

Zhang, Yajie and Shi, Zuoqiang

Subjects
Mathematics - Numerical Analysis, Mathematics - Analysis of PDEs
Abstract

Recently, we constructed a class of nonlocal Poisson model on manifold under Dirichlet boundary with global $\mathcal{O}(\delta^2)$ truncation error to its local counterpart, where $\delta$ denotes the nonlocal horizon parameter. In this paper, the well-posedness of such manifold model is studied. We utilize Poincare inequality to control the lower order terms along the $2\delta$-boundary layer in the weak formulation of model. The second order localization rate of model is attained by combining the well-posedness argument and the truncation error analysis. Such rate is currently optimal among all nonlocal models. Besides, we implement the point integral method(PIM) to our nonlocal model through 2 specific numerical examples to illustrate the quadratic rate of convergence on the other side.

Published
2021

70. Physical Model Guided Deep Image Deraining

Author

Zhu, Honghe, Wang, Cong, Zhang, Yajie, Su, Zhixun, and Zhao, Guohui

Subjects
Electrical Engineering and Systems Science - Image and Video Processing, Computer Science - Computer Vision and Pattern Recognition
Abstract

Single image deraining is an urgent task because the degraded rainy image makes many computer vision systems fail to work, such as video surveillance and autonomous driving. So, deraining becomes important and an effective deraining algorithm is needed. In this paper, we propose a novel network based on physical model guided learning for single image deraining, which consists of three sub-networks: rain streaks network, rain-free network, and guide-learning network. The concatenation of rain streaks and rain-free image that are estimated by rain streaks network, rain-free network, respectively, is input to the guide-learning network to guide further learning and the direct sum of the two estimated images is constrained with the input rainy image based on the physical model of rainy image. Moreover, we further develop the Multi-Scale Residual Block (MSRB) to better utilize multi-scale information and it is proved to boost the deraining performance. Quantitative and qualitative experimental results demonstrate that the proposed method outperforms the state-of-the-art deraining methods. The source code will be available at \url{https://supercong94.wixsite.com/supercong94}., Comment: IEEE ICME2020

Published
2020

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